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<strong>ERGONOMÍA</strong> <strong>OCUPACIONAL</strong><br />
INVESTIGACIONES Y APLICACIONES<br />
VOL. 3
<strong>SOCIEDAD</strong> <strong>DE</strong> <strong>ERGONOMISTAS</strong> <strong>DE</strong> MÉXICO A.C. (SEMAC)<br />
2010
<strong>ERGONOMÍA</strong> <strong>OCUPACIONAL</strong><br />
INVESTIGACIONES Y APLICACIONES<br />
VOL. 3<br />
EDITADO POR:<br />
CARLOS ESPEJO GUASCO<br />
Presidente Fundador SEMAC<br />
ENRIQUE <strong>DE</strong> LA VEGA BUSTILLOS<br />
Presidente SEMAC 2002-2004<br />
VICTORIO MARTINEZ CASTRO<br />
Presidente SEMAC 2008-2010
2010 Sociedad de Ergonomistas de México A.C. (SEMAC)<br />
ISBN 978-0-578-05757-6
Prefacio<br />
La Sociedad de Ergonomistas de México A.C. (SEMAC), como parte relevante de su<br />
actividad e interés en la difusión, promoción y apoyo a la ergonomía, ha organizado<br />
desde 1999 y de forma anual, su Congreso Internacional de Ergonomía. En Mayo de<br />
2010, el XII Congreso Internacional de Ergonomía tiene lugar en CD. Juárez, Chih., con<br />
la participación de ergonomistas profesionales e interesados en esta área.<br />
Aunque este último año ha sido, económicamente, muy difícil, eso no ha disminuido la<br />
calidad de los trabajos que se presentan este año. Se reúnen en este libro una selección<br />
de los trabajos, presentados en este congreso, más representativos de las diversas<br />
áreas que participan en la ergonomía, aportando diferentes investigaciones y soluciones<br />
a problemas específicos, con la finalidad de contribuir a la difusión, apoyo en la<br />
educación e investigación, de temas de interés para la ergonomía.<br />
Los editores, árbitros y comité académico, a nombre de la Sociedad de Ergonomistas de<br />
México, A.C., agradecemos a los autores de los trabajos aquí presentados su esfuerzo,<br />
e interés por participar y compartir su trabajo y conocimientos en el XII Congreso<br />
Internacional de Ergonomía de SEMAC. También agradecemos a los participantes y<br />
asistentes, provenientes de muy diversos lugares y formaciones, así como a todo el<br />
equipo de organización de este congreso, su valiosa aportación que estamos seguros<br />
derivará en el avance de la ergonomía en las Instituciones de Educación Superior y en<br />
la planta productiva nacional y mundial.<br />
Enrique de la Vega Bustillos<br />
Presidente SEMAC 2002 – 2004<br />
<strong>SOCIEDAD</strong> <strong>DE</strong> <strong>ERGONOMISTAS</strong> <strong>DE</strong> MÉXICO A.C.<br />
“Trabajo para optimizar el trabajo”<br />
Cd. Juárez, Chih. Mayo de 2010
ANTHROPOMETRY<br />
Ergonomía Ocupacional. Investigaciones y aplicaciones:. Vol 3<br />
CONTENT<br />
ANTHROPOMETRIC DATA OF STU<strong>DE</strong>NTS OF THE UNIVERSITY<br />
OF SONORA, SONORA, MEXICO<br />
Martina Elisa Platt Borbón, Amina Marín Martínez, María Magdalena<br />
Ayala, Rafael Castillo Ortega and Félix Montaño Valle<br />
ANTHROPOMETRY AND FACILITIES <strong>DE</strong>SIGN VERIFICATION<br />
OF NEW <strong>DE</strong>VELOPED PRESCHOOL LEVEL BUILDINGS IN THE<br />
EDUCATIONAL SECTOR OF HERMOSILLO, SONORA.<br />
Hiram Jesús Higuera Valenzuela, Manuel Sandoval Delgado<br />
<strong>DE</strong>SIGN ANTHROPOMETRIC REFERENCED LETTERS TO THE<br />
LABOR POPULATION OF CABORCA CITY IN SONORA<br />
MEXICO.<br />
Joaquín Vásquez Quiroga, Jesús<br />
1<br />
Rodolfo Guzmán Hernández,<br />
Enrique Javier de la Vega Bustillos.<br />
BIOMECHANICAL<br />
BIOMECHANICAL MO<strong>DE</strong>L TO ESTIMATE RECOVERY TIME ON<br />
HIGHLY REPETITIVE WORK IN MAQUILA OPERATIONS<br />
Fco. Octavio López Millán, Enrique Javier de la Vega Bustillos,<br />
Manuel Arnoldo Rodríguez Medina, Armando Ayala Corona<br />
VERIFICATION OF MAXIMUM ACCEPTABLE WEIGHT OF LIFT,<br />
TABULATED IN LIBERTY MUTUAL TABLES, IN WOMEN OF<br />
CABORCA<br />
Jesús Rodolfo Guzmán Hernández, Joaquín Vásquez Quiroga,<br />
Enrique Javier De La Vega Bustillos<br />
FORCE ANALYSIS IN HANDS ON HIGHLY REPETITIVE WORK<br />
IN MAQUILA OPERATIONS<br />
Fco. Octavio López Millán, Enrique Javier de la Vega Bustillos,<br />
MaríaJesúsTéllez Moroyoqui, LodevarPavlovichOviedo,<br />
Bertha Leticia Ortiz Navar<br />
<strong>DE</strong>SIGN AND WORK ANALYSIS<br />
ADVANTAGES OF THE ORTHOGONAL ARRANGEMENTS OF<br />
THE METHOD TAGUCHI IN THE <strong>DE</strong>SIGN OF EXPERIMENTS IN<br />
ERGONOMIC<br />
Alois Fabiani-Bello, Humberto García-Castellanos, Rosa Maria<br />
Reyes Martinez<br />
Page<br />
1<br />
14<br />
20<br />
35<br />
46<br />
55<br />
76
ERGONOMICS AND EDUCATION<br />
Ergonomía Ocupacional. Investigaciones y aplicaciones:. Vol 3<br />
ACA<strong>DE</strong>MIC ASSAYS FOR ERGONOMICS.<br />
Zoe Madai Cruz Purata, María del Sagrario Medina Rodríguez, Julio<br />
Gerardo Lorenzo Palomera<br />
OCCUPATIONAL ERGONICS<br />
ANALYSIS OF CORRELATION BETWEEN THE VARIABLES OF<br />
TEMPERATURE, STRENGTH AND CYCLES PER MINUTE TO<br />
PERFORM HORIZONTAL REPETITIVE MOVEMENTS OF THE<br />
WRIST<br />
Camargo Wilson Claudia, Rivera Valerio Abril A.,<br />
Rubio Martinez Jesus R., de la Vega Bustillos Enrique J.,<br />
López Bonilla Oscar R., Olguín Tiznado Jesús E.,<br />
Báez López Yolanda A.<br />
TEMPERATURE ANALYSIS ON WRIST SURFACE DUE<br />
REPETITIVE MOVEMENT TASKS USING SENSORIAL<br />
THERMOGRAPHY TO FIND OUT A POSSIBLE PATHOLOGY<br />
FOR A CTD<br />
Ordorica Villalvazo Javier, Camargo Wilson Claudia, De la Vega<br />
Bustillos Enrique, Olguín Tiznado Jesús E., López Bonilla Oscar R.,<br />
Limón Romero Jorge<br />
VIBRATION STUDY TO IMPROVE STRIPPING OPERATION<br />
IN A LITOGRAPHICS COMPANY<br />
Mario Ramírez Barrera, Jorge Valenzuela Corral, Athenea Núñez<br />
Sifuentes<br />
A <strong>DE</strong>SCRIPTIVE STUDY ABOUT THE INTEGRATION OF<br />
ERGONOMIC ATTRIBUTES ON THE SELECTION OF<br />
ADVANCED MANUFACTURING TECHNOLOGY -AMT-<br />
Aidé Maldonado Macías, Arturo Reallyvázquez, Guadalupe Ramírez,<br />
Jorge Garcia-Alcaraz, Salvador Noriega<br />
WORK EVALUATION<br />
REMOTE ERGONOMICS EVALUATIONS IN THE OFFICE<br />
Jeffrey E. Fernandez, Gabriel Ibarra-Mejia , and Brandy F. Ware<br />
COMPARATIVE ANALYSIS BETWEEN AN ERGONOMIC<br />
EVALUATION AND THE USERS' SATISFACTION OF NEW<br />
EDUCATIONAL CENTERS<br />
Martín Daniel Del Sol Rangel, Manuel Sandoval Delgado<br />
<strong>DE</strong>SIGN AND IMPLEMENTATION OF MANUFACTURING CELL<br />
WITH ERGONOMIC SUPPORT ANALYSIS<br />
Rigoberto Zamora Alarcón, Manuel Enrique Alcaráz Ayala,<br />
Julio César Romero González<br />
86<br />
98<br />
114<br />
128<br />
137<br />
151<br />
156<br />
163
ROSA MARIA REYES<br />
MARTINEZ<br />
Instituto Tecnologico de Cd.<br />
Juarez<br />
AI<strong>DE</strong> ARACELY MALDONADO<br />
MACIAS<br />
Universidad Autonoma de Cd.<br />
Juarez<br />
MA. ANTONIA BARRAZA<br />
Createc Cd. Juarez<br />
JEAN PAUL BECKER<br />
Ergon, Guadalajara, Jal.<br />
GABRIEL IBARRA MEJIA<br />
Universidad Autonoma de Cd.<br />
Juarez<br />
MIGUEL BAL<strong>DE</strong>RRAMA<br />
CHACON<br />
Valeo, Cd. Juarez<br />
Ergonomía Ocupacional. Investigaciones y aplicaciones:. Vol 3<br />
COMITÉ ACADÉMICO<br />
MONICA AI<strong>DE</strong> BARRERA<br />
Delphi, Cd. Juarez<br />
ELISA CHACON MARINEZ<br />
Nchmarketing, Cd. Juarez<br />
CARLOS ESPEJO GUASCO<br />
Visteon, Cd. Juarez<br />
FRANCISCO OCTAVIO<br />
LOPEZ MILLAN<br />
Instituto Tecnologico de<br />
Hermosillo<br />
VICTORIO MARTINEZ<br />
CASTRO<br />
MABE
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
"ANTHROPOMETRIC DATA OF STU<strong>DE</strong>NTS OF THE<br />
UNIVERSITY OF SONORA, SONORA, MEXICO"<br />
Martina Elisa Platt Borbón, Amina Marín Martínez, María Magdalena Ayala,<br />
Rafael Castillo Ortega and Félix Montaño Valle<br />
Industrial Engineering Department, Universidad de Sonora, Sonora, México<br />
1 mplatt@industrial.uson.mx, 2 amarin@industrial.uson.mx, 3 magdar@industrial.uson.mx, 4 rcastillo@industrial.<br />
RESUMEN<br />
uson.mx, 5 felixm@industrial.uson.mx<br />
Las cartas antropométricas dan la información acerca de las dimensiones de una población determinada y<br />
son muy utilizadas por los diseñadores. Los expertos en diseño afirman que una ayuda física diseñada<br />
para una población especifica, no es óptima para cualquier otra; ésto parece lógico, pero en nuestro país,<br />
no es posible ratificar o rectificar esta afirmación debido a que desconocemos las Cartas Antropométricas<br />
Mexicanas.<br />
La antropometría es la determinante de las condiciones ergonómicas; por tanto, los estudios<br />
antropométricos deben referirse a una población específica y de ahí nuestro interés por conocer las<br />
medidas de los estudiantes de la Universidad de Sonora.<br />
Se incluye un ejemplo de las tablas antropométricas por edad y por sexo de un estudio realizado a 227<br />
estudiantes de la Universidad de Sonora, Unidad regional Centro y se describe la metodología utilizada.<br />
ABSTRACT<br />
Anthropometric data gives information about the dimensions of a certain population and it is used by<br />
designers. Design experts affirm that physical equipment and facilities designed for a specific population,<br />
are not good for any other one; this seems logical, but, in our country, it is not possible to ratify or to rectify<br />
this statement because many of us ignore the Mexican Anthropometric data.<br />
Sociedad de Ergonomistas de México, A.C. 1
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
In order to design ergonomic living and working conditions, anthropometric principles must be applied;<br />
therefore anthropometric studies should refer to a specific population and it is our interest to know the<br />
dimensions and some physical features of the students of the University of Sonora.<br />
This research contains data collected in a sample of 227 students of the University of Sonora, Sonora,<br />
Mexico, from January to December, 2009; their body dimensions by age and sex, are depicted in figures 1<br />
and 2, and the methodology used is also described.<br />
INTRODUCTION<br />
Nowadays, men have reached an unusual development. Tools, equipment, machines and all kind of<br />
technology that are available aim for comfort and well-being in our daily life, as well as effectiveness,<br />
adaptability, prevention and for safety at work. These advances always arrive of the hand with new models<br />
of equipment, machines, tools or vehicles, which more dissimilar, force men to adapt themselves inside of<br />
or outside of them, implying possible risks, mainly at work places (McCormick, 1982).<br />
In all men’s activities, some or a lot of physical effort is needed, and they need and will continue needing<br />
physical assistance to reduce fatigue, to improve manufactured items or to produce them more quickly;<br />
some examples are: pincers or a hammer in a shop, a typewriter in an office, a pan in the kitchen or a<br />
stairway and its handrails in a building, etc.<br />
New scientific approaches and technological advances are key elements in designing to achieve higher<br />
productivity with almost perfect equipment and machinery. These items should eliminate the sources of<br />
risks and injuries. Designs should also take into account men’s physical characteristics, limitations and<br />
capabilities who will use them; designs must adapt physical tools to users and should avoid unnecessary<br />
efforts, tasks must be performed quickly, easily and safely, since individuals are more productive being<br />
comfortable at work.<br />
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Adapting tools to users or workers should not only be bounded to the operator, but to all persons that will<br />
work with them, such it is the case of the maintenance personnel. Any internal part of equipment or<br />
machine should be accessible and be able to provide the necessary space to make any repair (Flores,<br />
2001).<br />
Mexican workers also have to adapt themselves to working tools and conditions, mainly for three<br />
circumstances: there is a great quantity of equipment and machinery that were bought in foreign countries,<br />
which were not designed to be operated by the Mexican population; Mexican manufacturers produce their<br />
items erroneously, they design them as they were designed in other countries and the most dramatic<br />
situation is that they don't know the physical characteristics (anthropometric data) of the Mexican<br />
population, or perhaps they have not been published.<br />
The Mexican anthropometric data found in the literature, up to now, have little information and they were<br />
collected from certain regions.<br />
a. The Yucatan population's anthropometric data is a research carried out by George Dee Williams in<br />
1927 and published in 1931 by the Bureau of International Research of Harvard University and<br />
Radcliffe College under the name of "Mayan-Spanish Crosses in Yucatan".<br />
b. Anthropometric measurements of some selected world populations, were presented as a report by<br />
Robert M. White during the International Symposium of Engineering of Human Factors in 1972. This<br />
report presents the dimensions of the military Air Forces of eighteen (18) Latin American countries<br />
on the whole, but the reference of the source of information is not shown.<br />
c. Datos antropométricos de la población de Ciudad Juárez, is a study carried out in 1986 and 1987<br />
by the Center of Graduates of the Technological Institute of Ciudad Juárez. This investigation<br />
presents 50 anthropometric data of 987 adults, mainly from the maquiladora industry.<br />
d. “Estudio de ergonomía estática en una empresa textil Mexicana” was published in the journal<br />
Condiciones de Trabajo, in 1979.<br />
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Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
e. Anthropometry of female maquila workers, is a research published in the International Journal of<br />
Industrial Ergonomics in 1999 by Victor Liu, David Sanchez Monroy and Guillermo Parga. It<br />
presents twelve body dimensions of women workers in the maquiladora industry.<br />
f. Cartas antropométricas para la población laboral de la maquila de Ciudad Obregón, is a research<br />
conducted by Claudia Elena Mungarro Ibarra, in 2009.<br />
g. Cartas antropométricas de adultos con enanismo de 18 a 45 años de edad para el diseño de<br />
mobiliario, this survey was carried out in Mexico City, by Rubén Baptista Balderas, an Industrial<br />
Design graduate student at Centro Universitario UAEMéx Zumpango, who took body dimensions of<br />
adults with dwarfism among 18 to 45 years old to design different furniture.<br />
h. Cartas antropométricas de la población laboral del estado de Sonora, área serrana, this study<br />
gathered body dimensions of workers in the northeastern region of the state of Sonora, Mexico and<br />
it was performed by students of the Universidad de la Sierra in the state of Sonora in 2008.<br />
i. Cartas antropométricas de la población laboral de la República Mexicana, a research published by<br />
the Instituto Tecnológico of Hermosillo.<br />
Some employers may perceive that since tasks are designed or redesigned, whatever the operator will<br />
need may be, carefully, taken into account, but it may increase their investment, but in the long run,<br />
investment will be recovered and the gains will be financially enlarged.<br />
On the other hand, if an employee works comfortably when he/she is sitting down, he/she will not feel tired,<br />
will not feel any pain, and will be able to work easily and relaxed, and his/hers items quality will increase,<br />
as well as effectiveness and efficiency. In such scenario, health care costs will decrease and the<br />
employee’s moral will improve.<br />
Ergonomics principles can avoid injuries or painful illnesses that can handicap workers and make work<br />
places more comfortably safe in productive environments (McCormick, 1982).<br />
Anthropometric data`s main utilization is objects designed for human use, such as tools, furniture, work<br />
stations, facilities, etc. which optimize working and living conditions.<br />
Sociedad de Ergonomistas de México, A.C. 4
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
As it can be seen, designing for human use is a wide objective, and to achieve good results it is necessary<br />
to keep in mind that who is or will be a product’s customer. That is the main reason that anthropometric<br />
data is necessary as another tool for work designers, and its gathering takes time and it is quite expensive.<br />
OBJECTIVES<br />
To gather anthropometric data of students of the University of Sonora, in Hermosillo, Sonora, México, for<br />
different population strata, for:<br />
a) Age range (3), and<br />
b) Sex (2)<br />
METHODOLOGY<br />
A group of four trained people got the anthropometric data of 227 students. Three of the investigators (M.<br />
E. P. B. and A. M. M.) trained this group; they covered techniques, devices to use; and the required<br />
theoretical and practical knowledge to carry out the necessary activities.<br />
The trained group carried out the project with students of the University of Sonora in Hermosillo, Sonora,<br />
México. Students were asked to wear light clothing and to take off their shoes during the study.<br />
An anthropometer, a graduated scale in kilograms, and a survey of anthropometric data to register<br />
measurements were used.<br />
Measurements were taken by the students’ right side posture, when they were standing straight up, and<br />
also sitting down, in an erect position.<br />
1. Standing straight up. The individual remains standing straight, seeing toward the front, with the<br />
ankles together, the weight distributed equally in both feet and with his arms hanging naturally to his<br />
sides.<br />
2. Sitting down straight. The individual remains sitting down and straight, with his/her view toward the<br />
front, the arms relaxed and hanging, forearms and hands extended forward, thighs were horizontal,<br />
and his/her feet resting in an adjusted surface so that the knees were in an angle of 90 degrees.<br />
Sociedad de Ergonomistas de México, A.C. 5
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Data were gathered and processed in Excel software, and percentiles were later determined.<br />
Data were grouped by sex, age and geographical regions, in the following way:<br />
a. for sex: women and men,<br />
b. for age, from 17 to 20, from 21 to 23 and from 24 years old and up.<br />
c. Birthplace, the Mexican Republic was divided by several areas:<br />
North zone, for the States of Chihuahua, Coahuila, Durango, New León and Zacatecas.<br />
Centered area that includes the States of Aguascalientes, Mexico, Guanajuato, Hidalgo, Morelos, Puebla,<br />
Querétaro, San Luis Potosí', besides Mexico Federal District.<br />
Northern Pacific area: The states of the Northwestern area such as Sonora, Baja California, Sinaloa and<br />
Nayarit.<br />
Center Pacific area, for the states of Jalisco, Michoacán and Colima.<br />
South Pacific area: for the states of Guerrero, Oaxaca and Chiapas.<br />
Gulf of Mexico area, includes the states of Tamaulipas and Veracruz.<br />
The different areas were settled down, arbitrarily, following the approach of their geographical proximity.<br />
In figures 1 and 2, are shown the codes used, their description and the individual's position. This code was<br />
taken from a study carried out by the NASA.<br />
Sociedad de Ergonomistas de México, A.C. 6
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
UNIVERSIDAD <strong>DE</strong> SONORA. Carta Antropométrica<br />
Edad: 15-20 21-30 31-40 41-50 51-60 Sexo: F M<br />
Lugar de Nacimiento (Estado): _______________________________________ Ocupación: ____________________________________<br />
Lugar de Nacimiento (Estado): Padre: _____________________________ Madre: ______________________________________<br />
Analista: _________________________________________________________ (Usar ropa ligera y ajustada al cuerpo)<br />
920 Peso (Kg) 122 Ancho de hombros<br />
805 Estatura 223 Ancho de pecho<br />
328 Altura al ojo 457 Ancho de cadera (parado)<br />
23 Altura al hombro 32 Largo de brazo<br />
309 Altura al codo 67 Profundidad del pecho<br />
949 Altura a la cintura (ombligo) 430 Circunferencia de la cabeza<br />
398 Altura al glúteo 639 Circunferencia del cuello<br />
973 Altura a la muñeca 230 Circunferencia del pecho<br />
66 Altura a los nudillos 931 Circunferencia de la cintura<br />
265 Altura al dedo medio 68 Circunferencia del brazo<br />
797 Ancho de brazos extendidos<br />
lateralmente<br />
798 Ancho de codos con las manos<br />
al centro del pecho<br />
178 Circunferencia de la cadera<br />
69 Circunferencia de la pantorrilla<br />
80 Distancia de la pared al dedo medio 144 Distancia de oído a oído sobre la<br />
cabeza<br />
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Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
752 Distancia de la pared al nudillo 165 Ancho de la cara a la altura de las<br />
patillas<br />
Figure 1. Codes used, their description, and the individual's position.<br />
427 Ancho de la cabeza 912 Altura del asiento a los nudillos con los<br />
brazos extendidos hacia arriba<br />
595 Altura de la barbilla a la parte superior<br />
de la cabeza<br />
200 Longitud desde el respaldo del asiento a<br />
la parte posterior de la rodilla<br />
441 Longitud de la cabeza 194 Longitud desde el respaldo del asiento al<br />
frente de la rodilla<br />
420 Longitud de la mano 2fgm Altura desde el suelo a la cabeza<br />
(sentado)<br />
656 Longitud de la palma de la mano 4fgm Altura desde el suelo al asiento<br />
411 Ancho de la palma de la mano 529 Altura desde el suelo a la rodilla<br />
(sentado)<br />
859 Ancho de muslos con las rodillas juntas<br />
(sentado)<br />
678 Altura desde el suelo a la parte posterior<br />
de la rodilla (sentado)<br />
758 Altura del asiento a la cabeza 70 Longitud desde el codo al dedo medio<br />
330 Altura del asiento al ojo 507 Ancho de la espalda con los brazos<br />
extendidos hacia el frente<br />
25 Altura del asiento al hombro 459 Ancho de la cadera (sentado)<br />
Sociedad de Ergonomistas de México, A.C. 8<br />
Elaboró: GF y SM
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
312 Altura del asiento al codo a 90° 775 Longitud del pie<br />
856 Altura al muslo 776 Alto del pie<br />
914 Altura del asiento al dedo medio con<br />
brazos extendidos hacia arriba<br />
777 Ancho del pie<br />
Figure 2. Codes used, their description, and the individual's position.<br />
Sociedad de Ergonomistas de México, A.C. 9<br />
Elaboró: GF y SM
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
RESULTS<br />
Six anthropometric data were obtained from a sample of 227 students, for women and men, for three group<br />
of ages from 17 to 20, from 21 to 23 and from 24 to 54 years old.<br />
Hereby are presented two anthropometric surveys where body dimensions are described, measurements are<br />
in centimeters and weight is shown in kilograms for 5 th , 50 th and 95 th percentiles of a women’s sample<br />
(figure 3) and for a masculine sample (figure 4), both, from 17 to 20 years old. In figure 5 data shows a<br />
sample size of 227 masculine and feminine students by age range and sex.<br />
Measurement’s Desription 5% 50% 95% Measurement’s Description 5% 50% 95%<br />
Weight 37.17 66.6 96.02 Length of head 17.042 19.241 21.441<br />
Stature 151.77 165.54 179.3 Length of hand 15.828 17.594 19.36<br />
Length of palm of hand 7.831 9.8366 11.842<br />
Height standing Width of palm of hand 4.5519 7.8598 11.168<br />
Eye 139.97 153.73 167.5 Diameter of grabs (interior) 36.064 45.146 54.228<br />
Shoulder 123.24 136.02 148.8<br />
Elbow 86.196 107.4 128.6 Heights sitting<br />
Waist 91.871 101.94 112 Height to head from seat 71.443 85.524 99.605<br />
Buttock 65.34 74.432 83.52 Height to eye from seat<br />
Height to shoulder from<br />
67.182 75.012 82.842<br />
Wrist 53.194 82.124 111.1 seat<br />
Height to elbow from seat,<br />
50.45 59.456 68.462<br />
Middle finger 54.842 63.695 72.55 90 degrees 20.364 24.951 29.538<br />
Width of extended arms 151.27 166.63 182 Height to thigh from seat 10.891 14.046 17.202<br />
Width of elbows to the<br />
Height to Middle finger<br />
center of chest 70.412 85.588 100.8 from seat, arms up 117.5 129.26 141.01<br />
Length of arm extended<br />
Height to center of fist, arms<br />
from the wall 64.072 81.687 99.3 up 100.41 122.3 144.2<br />
Length to the center of the<br />
Height to head from floor<br />
fist from the wall 51.492 73.712 95.93 sitting<br />
Hight to seat from floor<br />
121.12 131.11 141.1<br />
Width of shoulders standing 34.828 42.038 49.25 sitting 23.215 49.154 75.092<br />
Width of chest standing 24.719 30.34 35.96 Popliteal to buttocks<br />
Length from knees to<br />
39.537 47.641 55.746<br />
Width of hips standing<br />
Circumferencia of neck<br />
26.245 33.701 41.16 buttocks 48.308 59.027 69.745<br />
standing<br />
Circumferencia fo chest<br />
23.618 35.539 47.46 Height from floor to popliteal 35.818 43.388 50.958<br />
standing 73.352 90.66 108 Height from floor to knee 40.054 52.266 64.477<br />
Circumferencia of waist<br />
Length from elbow to<br />
standing 55.12 79.619 104.1 middle finger<br />
Width of back with arms<br />
40.634 44.907 49.18<br />
Circumference of hips<br />
extended forward –forward<br />
standing 81.893 99.361 116.8 reach 34.85 40.587 46.323<br />
Circumference of head 46.695 54.395 62.1 Width of hips, sitting 32.447 38.468 44.489<br />
Distance from ear to ear<br />
Width of thighs with knees<br />
over head<br />
Width of face to the height<br />
26.672 34.971 43.27 meeting 30.701 37.212 43.723<br />
of sideburns 11.977 13.563 15.15 Length of foot 21.381 24.137 26.892<br />
Width of head<br />
Height of chin to superior<br />
13.645 14.973 16.3 Width of foot 6.4972 8.4366 10.376<br />
part of head 18.517 22.146 25.78 Height of instep 4.3354 6.2829 8.2305<br />
Figure 3. Body dimensions for a femenine sample from 17 to 20 years old.<br />
Sociedad de Ergonomistas de México, A.C. 10
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Measurement’s description 5% 50% 95% Measurement’s description 5% 50% 95%<br />
Weight 42.488 71.49375 100.49 Length of head 16.075 19.574 23.073<br />
Stature 159.93 171.5791 183.23 Length of hand 15.673 18.054 20.435<br />
Length of palm of hand 8.6763 10.373 12.07<br />
Height standing Width of palm of hand 6.6558 8.1094 9.5629<br />
Eye 146.22 158.5875 170.955 Diameter of grabs (interior) 41.309 47.465 53.621<br />
Shoulder 130.06 141.2395 152.41<br />
Elbow 92.509 109.3958 126.28 Heights sitting<br />
Waist 95.292 105.0958 114.9 Height to head from seat 68.123 86.91 105.7<br />
Buttock 54.349 79.39791 104.44 Height to eye from seat 67.85 77.194 86.538<br />
Wrist 59.077 85.08333 111.08 Height to shoulder from seat<br />
Height to elbow from seat,<br />
51.535 61.767 71.998<br />
Middle finger 57.349 65.675 74.000 90 degrees 20.315 25.654 30.993<br />
Width of extended arms 160.06 173.7833 187.50 Height to thigh from seat 11.199 14.198 17.196<br />
Width of elbows to the center<br />
Height to Middle finger from<br />
of chest 80.408 88.92812 97.448 seat, arms up 123.05 135.74 148.43<br />
Length of arm extended<br />
Height to center of fist, arms<br />
from the wall 74.883 84.65416 94.425 up 113.39 126.16 138.93<br />
Length to the center of the<br />
Height to head from floor<br />
fist from the wall 65.872 74.74166 83.6111 sitting<br />
Hight to seat from floor<br />
122.9 132.74 142.57<br />
Width of shoulders standing 35.141 44.8 54.458 sitting 25.36 49.129 72.899<br />
Width of chest standing 26.262 31.33333 36.4043 Popliteal to buttocks<br />
Length from knees to<br />
41.01 48.425 55.84<br />
Width of hips standing<br />
Circumferencia of neck<br />
29.324 35.1 40.876 buttocks 51.866 59.494 67.121<br />
standing<br />
Circumferencia fo chest<br />
18.107 38.59791 59.088 Height from floor to popliteal 37.174 43.798 50.422<br />
standing 75.157 92.11041 109.06 Height from floor to knee 45.236 52.631 60.026<br />
Circumferencia of waist<br />
Length from elbow to middle<br />
standing 62.925 84.41458 105.90 finger<br />
Width of back with arms<br />
40.184 46.278 52.372<br />
Circumference of hips<br />
extended forward –forward<br />
standing 81.922 97.05833 112.19 reach 38.252 43.581 48.911<br />
Circumference of head 46.276 56.28666 66.297 Width of hips, sitting 31.955 38.346 44.737<br />
Distance from ear to ear over<br />
Width of thighs with knees<br />
head<br />
Width of face to the height of<br />
25.215 35.57708 45.939 meeting 29.586 36.777 43.969<br />
sideburns 12.364 14.04375 15.723 Length of foot 22.467 25.502 28.537<br />
Width of head<br />
Height of chin to superior<br />
13.581 15.52604 17.471 Width of foot 6.2461 8.6625 11.079<br />
part of head 19.43 22.74375 26.057 Height of instep 4.812 6.5781 8.3443<br />
Figure 4. Body dimensions of a masculine sample from 17 to 20 years old.<br />
Sociedad de Ergonomistas de México, A.C. 11
Estratum by age<br />
17-20<br />
21-23<br />
24-54<br />
TOTALS<br />
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Masculine<br />
Feminine<br />
Sociedad de Ergonomistas de México, A.C. 12<br />
48<br />
85<br />
3<br />
136<br />
Figure 5. Sample size, grouped by age and sex of students of the Universidad de Sonora.<br />
CONCLUSIONS AND SUGGESTIONS<br />
Ergonomics emerged exclusively to increase worker's productivity, with time, it has become into a<br />
multidiscipline, it looks forward to make tools more functional and spaces habitable, to improve aspects like<br />
the men’s safe, comfort and health.<br />
At present times, muscular – skeletal problems are often found in workers, "in such situations applied<br />
Ergonomics is useful because it improves adaptability of physical persons’ limitations to environmental<br />
conditions and to work tools, avoiding the development of pathologies like tendinitis, cervical and lumbar<br />
injuries, among others."<br />
Products, tools, machines, work places and furniture should be designed thinking of the activity or activities<br />
that people will carry out on them. A work place can have more than one worker and its design should be<br />
adjustable, that is why sometimes, it is necessary to build products of several sizes in such a way that<br />
someone would have the possibility to choose the one that better adapts to the user's necessities, the other<br />
one, would be to create products that are adjustable in a certain range of body dimensions, making necessary<br />
to know the benefits and costs in such a way that decisions that are taken are the correct ones.<br />
41<br />
47<br />
3<br />
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As it can be seen, everything that is manufactured, elaborated to interrelate with man should use their<br />
dimensions, it is necessary to know human anthropometry.<br />
The anthropometric data gathered in this research is one more effort added to those that were made<br />
previously in Mexico. Body dimensions of students of the University of Sonora, in Hermosillo, Sonora,<br />
Mexico includes male and female from 17 to 20, 21 and from 23 to 24 years old and older students; natives<br />
and non natives from Hermosillo. These sample is build of 60.87% men and 39.83% women, 100% belong<br />
to the North Pacific area and 93.52% were born in the state of Sonora.<br />
Suggestions that can be made are: to invite researchers, education institutions and companies to develop<br />
anthropometric data of Mexican populations, aiming to design production systems that will fulfill their main<br />
goals: to increase productivity and to produce high product quality, optimizing workers’ safe and comfort at<br />
the same time, so that they would allow them to compete in today’s global business.<br />
REFERENCES<br />
1. McCormick, Ernest and Sanders, Mark. (1982). Human Factors in Engineering and Design. United<br />
States of America. McGraw-Hill Book Company.<br />
2. Neufert, Ernest. (1977). The Art of Projecting in Architecture. Barcelona, Spain. Editorial Gustavo<br />
Gil, S. A.<br />
3. Instituto Mexicano del Seguro Social (1982). Lecturas en materia de seguridad social. Ergonomía.<br />
México.<br />
4. Flores, Cecilia. (2001). Ergonomía para el diseño. Designio.<br />
5. Mondelo, Gregori, de Pedro Gómez. (2002). Ergonomía 4. El trabajo en oficinas. Editotial<br />
Alfaomega.<br />
6. Murrell, K. F. H. (1979). Ergonomics. London, England. Chapman & Hall.<br />
7. Konz, Stephan. (2004) Work Design. Columbus, Unites States. Grid Publishing.<br />
8. Unites States of America. NASA. (1987). Anthropometric Source Book, Vol 2: A Handbook of<br />
Anthropometric Dates.<br />
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ANTHROPOMETRY AND FACILITIES <strong>DE</strong>SIGN VERIFICATION OF NEW<br />
<strong>DE</strong>VELOPED PRESCHOOL LEVEL BUILDINGS IN THE EDUCATIONAL<br />
SECTOR OF HERMOSILLO, SONORA.<br />
Hiram Jesús Higuera Valenzuela 1 , Manuel Sandoval Delgado 1<br />
1 Departamento de Investigación y Posgrado<br />
Instituto Tecnológico de Hermosillo<br />
Ave. Tecnológico S/N Colonia Sahuaro<br />
Hermosillo, Sonora 83170<br />
Corresponding author’s e-mail: hiram.higuera@gmail.com, msandoval@ith.mx<br />
Resumen: Esta investigación nace de la problemática de la no existencia de tablas<br />
antropométricas de la población infantil principalmente en la edad de preescolar en México, las<br />
utilizadas por el Instituto Nacional de la Infraestructura Física Nacional no incluyen datos<br />
pertenecientes a infantes en edad de preescolar, las cuales se utilizan para la elaboración de<br />
mobiliario y dimensionamiento en el diseño de las instalaciones educativas (INIFED).<br />
Antropometría infantil.<br />
Abstract: This research comes from the lack of anthropometric charts for Mexican children in preschool<br />
level, the charts used by the Instituto Nacional de la Infraestructura Física Nacional<br />
(National Institute for Educational Facilities) do not include data from pre-school level children;<br />
those charts are used to build furnishing and to determine the right size of the facilities (INIFED).<br />
Children’s Anthropometry<br />
1. INTRODUCTION<br />
Current situation in developing countries and economic growth, lack of in-house technologies and<br />
economic and technological dependence favor the use of models designed by other cultures<br />
(Oborne, 2007).<br />
2. OBJETIVES<br />
Check if design is within measurements found in the anthropometry charts in new pre-school level<br />
buildings in Hermosillo, Sonora during 2007 and 2008, since previously built schools show a lot of<br />
mistakes regarding the facilities’ size and the furnishing causing a lot of discontents and troubles<br />
in teachers and family parents in pre-school level buildings.<br />
3. METHODOLOGY<br />
Sociedad de Ergonomistas de México, A.C. 14
3.1 Programming stage<br />
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
a) The aim of this anthropometric research must be very clear, specifying if data collected will<br />
be used for a new design, redesign or to create a general purpose database.<br />
b) It is necessary to define the kind of anthropometric technique that will be applied, which can<br />
be “Static Anthropometry” or “Dynamic Anthropometry”. (Flores G., 1997).<br />
Static anthropometry measures the body still. It measures the skeleton between specific<br />
anatomic points. Dynamic or functional anthropometry it’s the one which measures the body in<br />
motion, acknowledging that the actual reach of a person’s arm it’s not equal to the length of the<br />
arm itself, but it takes into consideration the additional reach provided by the movement of the<br />
shoulder and torso when a person is working (Ergocupacional).<br />
c) Once that the kind of anthropometric technique has been chosen, all the measures that will<br />
be used need to be specified and for this we need to keep in mind our final goal. In order to<br />
choose the measures we need to take, we must refer to the general anthropometric set<br />
(static or dynamic), taking into account the name and standard reference points in order to<br />
keep the techniques systematization.<br />
d) Once that the measures to be taken have been defined, the anthropometric chart to be<br />
used needs to be designed. A copy of the chart for each subject needs to be built.<br />
e) Besides the good quality and accuracy of the measuring equipment, portability it’s<br />
important, since most of the time it will be necessary to go where people who will be<br />
measured is. The most basic equipment must include anthropometric chart, portable<br />
anthropometer, flexometer, and tape measure. (Flores G., 1997).<br />
Figure 1. Anthropometric chart and portable anthropometer.<br />
3.2 Sampling<br />
In this stage it’s when individuals in new facilities start to be measured in order to collect<br />
raw data; this is 32 measures by each individual.<br />
3.3 Statistics Analysis<br />
Once that the data is collected, it is analyzed and an anthropometric chart is built;<br />
percentiles 95, 50, 5 come from this chart, those are used to build facilities and furnishing.<br />
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The impossibility to make a design for the whole population forces us to pick a segment<br />
which includes the data in between. Thus, highest and lowest values are left out and focus on the<br />
90% of the population. As a norm, the practical totality of anthropometric data is expressed in<br />
percentiles. In order to make this research more effective, population is broken into percentages<br />
categories, sorted from lowest to highest according to a specific body measure. For example, the<br />
first height percentile indicates that 99% of the individuals measured would be above this<br />
dimension. In the same way, a percentile of 95% in height would state that only 5% of the<br />
individuals measured would be over it, since the remaining 95% would be just as tall or shorter.<br />
(Panero, 1993).<br />
3.4 Steps to get percentiles<br />
1. Summation of raw data is calculated In a spreadsheet (total of measures), mean or<br />
average is calculated using the following formula:<br />
= Data mean or average<br />
ΣX = Summation of the values of all the measures.<br />
n = Number of elements of the sample.<br />
2. Standard deviation it’s calculated, which defines the individual deviation of each<br />
measure regarding to the mean.<br />
s 2 = Variation of the sample.<br />
s = Standard variation of the sample.<br />
x = Value of the measures.<br />
= Mean of the sample.<br />
n - 1 = Number of measures of the sample -1<br />
3. Standard deviation of the unit it’s calculated, which is called “z”, where z equals to:<br />
x = Random variable value<br />
= Average distribution of the random variable.<br />
s = Standard variation of this distribution.<br />
z = Number of standard deviations of x regarding the mean of this distribution.<br />
(Navidi, 2006).<br />
Sociedad de Ergonomistas de México, A.C. 16<br />
(1)<br />
2<br />
3<br />
(4)
(DINBelg)<br />
4. Percentiles are calculated<br />
4. RESULTS<br />
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Since this is an ongoing research, some of the necessary measures are still missing in order to<br />
conduct a full test of the facilities and furnishing, however, there is an anthropometric chart with<br />
the data collected so far and it is possible to get preliminary results in order to get the dimensions<br />
for facilities and furnishing.<br />
In this example the dimensions of the sink and classroom chairs will be used.<br />
In order to calculate height and width for the sink measures 949 (height to the waist) and 752<br />
(distance from the wall to the center of the fist)<br />
Results for 949<br />
X = 61.55<br />
S = 4.88<br />
5 % = 61.55 – (4.88 x 1.65) = 53.498 cm (9)<br />
Results for 752<br />
X = 46.26<br />
S = 3.66<br />
5 % = 46.26 – (3.66 x 1.65) = 40.221 cm (10)<br />
Sociedad de Ergonomistas de México, A.C. 17<br />
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6<br />
7<br />
(8)
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Figure 2. Sink dimensions<br />
In order for most of the children to be able to use the sink without any problems percentile 5<br />
from mean 949 and 752 was used.<br />
Measures 200 (length from the back of the knee to the back of the chair), 678 (height from<br />
the ground to the back side of the knee), 459 (width of hips, sitting down), 25 (height from the seat<br />
to the shoulder) are used in order to get the dimensions of the chair.<br />
Results for 200<br />
X = 28.82<br />
S = 2.13<br />
5 % = 28.82 – (2.13 x 1.65) = 25.3055 cm (11)<br />
Results for 678<br />
X = 28.98<br />
S = 2.38<br />
5 % = 28.98 – (2.38 x 1.65) = 25.053 cm (12)<br />
Results for 459<br />
X = 22.09<br />
S = 1.95<br />
5 % = 22.09 + (1.95 x 1.65) = 25.3075 cm (13)<br />
Results for 25<br />
X = 37.56<br />
S = 2.54<br />
5 % = 37.56 – (2.54 x 1.65) = 33.369 cm (14)<br />
Sociedad de Ergonomistas de México, A.C. 18
5. CONCLUSIONS<br />
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Figure 3. Chair dimensions<br />
This research is extremely important since there are no anthropometric charts for pre-school level<br />
children in Mexico. These charts are used to build furnishing and determine the size of new<br />
schools buildings. This project aims to get the necessary information in order to build these charts.<br />
6. REFERENCES<br />
Flores G., Cecilia (1997) Antropometría Aplicada, Primer Encuentro Internacional de Ergonomía,<br />
Instituto Tecnológico de Mérida, Mérida Yucatán.<br />
Oborne, David J. (1990 reimpresión 2001), Ergonomía en acción la adaptación del medio de<br />
trabajo al hombre. – 2ª edición – México: Trillas.<br />
INIFED (Instituto Nacional de la Infraestructura Física Educativa 2008), Normas y<br />
Especificaciones para Estudios, Proyectos, Construcción e Instalaciones, Volumen 3<br />
Habitabilidad y Funcionamiento, Tomo III Diseño de Mobiliario.<br />
http://www.inifed.gob.mx/templates/normas%20t%C3%A9cnicas.asp (Visited on May 15,<br />
2009).<br />
ERG<strong>OCUPACIONAL</strong> Uso de tablas antropométricas en ergonomía,<br />
http://www.ergocupacional.com/4910/35922.html (Visited on March 8, 2010).<br />
Panero Julios (1993) Las dimensiones humanas en los espacios interiores. Ed. G. Gili, S.A.<br />
México, D.F.<br />
Navidi William (2006) Estadística para ingenieros y científicos. McGraw-Hill Interamericana.<br />
México, D.F.<br />
DINBelg Body dimensions of the Belgian population Formulas,<br />
http://www.dinbelg.be/formulas.htm (Visited on March 8, 2010).<br />
Sociedad de Ergonomistas de México, A.C. 19
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1<br />
M.C. Joaquín Vásquez Quiroga 1 , M.C. Jesús Rodolfo Guzmán Hernández 2 , Dr. Enrique Javier de<br />
la Vega Bustillos 3 .<br />
1<br />
2<br />
3<br />
<strong>DE</strong>SIGN ANTHROPOMETRIC REFERENCED LETTERS TO THE LABOR<br />
POPULATION OF CABORCA CITY IN SONORA MEXICO.<br />
Program Coordinator and Professor, Department of Physics, Mathematics and Engineering,<br />
Universidad de Sonora, Caborca Sonora, México.<br />
jovaqui@caborca.uson.mx<br />
Professor and Researcher at the Instituto Tecnológico de Hermosillo, Mexico<br />
e_delavega_mx@yahoo.com<br />
Professor, Department of Physics, Mathematics and Engineering<br />
Universidad de Sonora, Caborca, Sonora, México.<br />
rguz@caborca.uson.mx<br />
RESUMEN<br />
Esta investigación es el resultado de las mediciones de 50 variables antropométricas de 200<br />
personas en edad laboral de la Ciudad de Caborca Sonoro México, con el objetivo de poder<br />
hacer una aportación importante a la creación de cartas antropométricas para la población<br />
mexicana. En la actualidad son pocos los datos que se tienen de las medidas antropométricas de<br />
la población mexicana, haciéndose necesario utilizar las medidas de otros países en donde las<br />
condiciones y complexión física son diferentes.<br />
Las cartas antropométricas que aquí se obtuvieron están distribuidas por grupos de edad, sexo y<br />
lugar de origen. Este trabajo puede ser el inicio de investigaciones similares en otras poblaciones<br />
de México y llegar a tener un registro antropométrico del total de la población mexicana, para<br />
poder desarrollar estaciones o espacios de trabajo que se adapten a la población, herramientas,<br />
ropa, equipo de protección personal como cascos y guantes, calzado, lo mismo que lugares de<br />
descanso.<br />
Palabras claves: Cartas Antropométricas, Antropometría y Ergonomía.<br />
ABSTRACT<br />
This research is the result of 50 anthropometric measurements of 200 people of working age of<br />
Caborca Sonora Mexico City, in order to be able to make a significant contribution to creating<br />
cards for the Mexican population anthropometric. At present there are few data have<br />
anthropometric measurements of the Mexican population, making it necessary to use measures<br />
other countries where conditions and physique are different.<br />
The anthropometric letters were obtained here are divided by age, sex and place of origin. This<br />
work may be the beginning of similar investigations in other populations of Mexico and get to have<br />
a record of all anthropometric Mexican population, to develop stations or workspaces that are<br />
tailored to the people, tools, clothing, protective equipment personal as helmets and gloves,<br />
footwear, as well as resting places.<br />
Keywords: Anthropometric Letters, Anthropometry and Ergonomics.<br />
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Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
1. INTRODUCTION<br />
It is now of vital importance to take into account the design and the anatomic structure of<br />
individuals to understand and develop all those areas in which performance involves human<br />
beings, this is not new and has been studied before in different countries and not with measures<br />
aimed at the Mexicans. The purpose of a study of this type is able to physically help the worker in<br />
all areas where it is involved, such as designing work spaces suitable for each person, the design<br />
of tools, safety equipment and personal protection clothing, and have references dimensional<br />
population.<br />
With all the technological advances that have occurred, you can have a better life, as<br />
studies have been developed in several areas, one of them is the anthropometry, with which they<br />
determine the dimensions of the human body, in this area there are some studies in developed<br />
countries, but very few of the Mexican population. Hence the interest start recording<br />
anthropometric data, thinking about making a contribution to the creation of anthropometric cards<br />
to this population. The creation of these cards is essential to have a population register, in order<br />
to make designs of stations, the design of tools and equipment, etc.., Always trying the user is<br />
comfortable and without risk of injury by position not normal. This is important to understand their<br />
measurement and to determine the field of development or dimensional capabilities that people<br />
have. For this reason the study will focus to working anthropometric cards of population of H.<br />
Caborca, Sonora, and this is an important input to record anthropometric measurements of the<br />
Mexican population.<br />
Throughout history, many investigations that have been developed in the area of<br />
anthropometry. In more current times these investigations have risen to be an important support<br />
for ergonomics, this is the case:<br />
Annis (1996) did an analysis of anthropometric changes the size and body shapes as they<br />
get older people, to see the implications of these changes in the dimensions of workspaces.<br />
Gosseens (1998) studied the dimensions of the seats of five different types of civil aircraft.<br />
The results were compared with existing standards and biomechanical criteria. It was evident that<br />
these seats failed to meet requirements of depth, slope, height of lumbar support and armrests.<br />
Therefore, none of these seats allow the pilot was in a comfortable sitting posture. In comparison<br />
with aviation standards, the anthropometric dimensions were not satisfactory.<br />
Panagiotopoulou (2003) developed a study for the purpose of comparing the size of<br />
primary school students, with the dimensions of the desks, to determine if the dimensions of the<br />
furniture is well designed and see if they promote good posture sitting considering the dimensions<br />
of children.<br />
Jung (2005) developed a prototype of an adjustable chair for educational institutions, where<br />
they assess their suitability according to international standards. His research began with simple<br />
mechanisms for adjusting the height of chair legs and backrest height and seat depth.<br />
In Mexico, these investigations have increased due to the recommendations made in the<br />
Federal Regulation on Safety, Hygiene and Environment Working in Article 102 and as SEMAC<br />
associations (Society of ergonomic Mexicana AC), which organizes conferences in presented<br />
research papers such as:<br />
Ergonomic design for computer work stations, presented by Martinez (2000).<br />
Implementation of an ergonomic process for the industry for control musculoskeletal<br />
injuries, presented by Sánchez (2002).<br />
Research and Ergonomics in Mexico, presented by de la Vega (2004).<br />
Sociedad de Ergonomistas de México, A.C. 21
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
In developing this work is clearly important that represents the human resources within an<br />
organization, since this depends on the effectiveness of the production process. Therefore, the<br />
objective of the development of this research is the creation of letters of the anthropometric<br />
measurements of the working population of the City of Caborca, by age group, sex and place of<br />
origin.<br />
Obtaining anthropometric cards may be made designs for the population, helping<br />
businesses and people in general. Currently there are very few reliable records of the<br />
anthropometric dimensions of these people, so it is taken as the measures of other countries<br />
where physique is different and the conditions too.<br />
When designing industrial products is important to provide who are the users to succeed in<br />
the product, taking into account different body sizes, safety and human comfort, it is here that<br />
involves anthropometry (Reeder 2003).<br />
Hence the great importance of anthropometric data to researchers from the human factor,<br />
for practical use with these, such as would be the design of clothing, tools, to provide statistical<br />
guidelines for product design and build models biomechanical. (Park, Kim 1997).<br />
According Cavassa (2004) there are two types of anthropometrics: anthropometry static or<br />
structural, which refers to the dimensions in which the body is in static state, for example, height,<br />
weight, etc.<br />
The other type is the dynamic anthropometry: it refers to taking action where the body is<br />
operating, for example stretching one arm to reach something.<br />
At the time of wanting to design, there are some factors that influence the anatomical<br />
structure of the human body are: age (until maturity), sex (male, female), race, occupation,<br />
clothing (especially in cold weather ) and even the time of day (in the morning the people are<br />
measuring 6 mm more, because the spinal discs are not compressed (Konz 1999).<br />
When will develop designs for a group of people is important to take into account some<br />
principles such as:<br />
1. Design principle to extremes: this design takes the maximum and minimum value of the<br />
characteristics of user populations.<br />
2. Adjustable design principle: it is used for facilities and equipment that can be adapted to various<br />
individuals.<br />
3. Design principle for the average: this approach is less expensive but less used, since it is<br />
difficult to get the design that fits 50% of the population (Niebel 2001)<br />
The anthropometric cards is to develop a record of human body stockings for people to<br />
have a higher confidence level to develop a design such as a workstation, machinery, equipment,<br />
clothing, etc. such is the case study by Mohammad (2005) which record some measures of hand.<br />
There are an infinite number of steps you can take the human body as recommended by the<br />
manual of procedures (Secretariat 2002). For the case study of this work, selected 50 of them,<br />
according to the definitions used in similar anthropometric examinations conducted by the<br />
National Aeronautics and Space Administration (NASA 1978).<br />
2. MATERIALS AND METHODS<br />
For the development of the research team used the following:<br />
• three anthropometer model 01140, 01290 and 01291 marks Lafayette.<br />
• One stadimeter marks Seca.<br />
• One analog scale marks Seca.<br />
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• Two measuring tape marks Powerlock Stanley.<br />
• Two flexible tapes.<br />
• Two calibrators marks Chicago Brand.<br />
• Two chairs designed with a height adjustment system.<br />
• One calibrated cone diameter grip.<br />
• One computer for recording information.<br />
The methodology for taking the measures was as follows:<br />
It had a special area for training and standardization process of the four assistants in order to<br />
achieve uniformity in the way of measuring.<br />
The measurements were conducted in a private room and quiet, being present only the<br />
individual, the analyst and an assistant.<br />
People who were measured were treated with respect and care, trying to earn their trust.<br />
Before the measurement was given a brief explanation of the steps, procedures and<br />
requirements for measurement.<br />
Was prepared and calibrated all equipment necessary to make anthropometric measurements,<br />
ensuring that all necessary materials are available.<br />
To begin with the taking of measures, the person must wear few clothes, nothing in the head<br />
or feet, the surface of the floor, seat or platform must be flat, horizontal and non-compressible,<br />
measure the right side of the person. At the time of the measures breathing should be light.<br />
The 50 measures that were recorded for each person are:<br />
Code Name of the measure<br />
N920 Weight<br />
N805 Stature<br />
N328 Standing eye height to<br />
N23 Standing shoulder height<br />
N309 The standing elbow height<br />
N949 Standing waist height<br />
N398 Height standing gluteus<br />
N973 Standing tall on the wrist<br />
N265 Standing height to the middle finger<br />
N797 Width arms outstretched<br />
N798 Width at center chest elbows<br />
N80 Arm length from the wall<br />
N752 Distance from wall to the center of the fist<br />
N122 Standing shoulder width<br />
N223 Standing chest width<br />
N457 Standing Hip Width<br />
N639 Standing neck circumference<br />
N230 Standing chest circumference<br />
N931 Waist circumference stands<br />
N178 Standing hip circumference<br />
N430 Head circumference<br />
N144 Distance from ear to ear on the head<br />
N165 Face width to the height of the pins<br />
N427 Head width<br />
N595 Height of the chin to the top of head<br />
N441 Head length<br />
N420 Length of hand<br />
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N656 Length of the palm<br />
N411 Width of palm<br />
N402 Grip diameter<br />
N758 Seat height sitting at the head<br />
N330 Seat height sitting in the eye<br />
N25 Seat height sitting shoulder<br />
N312 Seat height to seated elbow to 90<br />
N856 Sitting thigh-high<br />
N914 Seat height to the middle finger sitting<br />
N912 Height to the center of the cuff arms up<br />
N2FGM Height of sitting down<br />
N4FGM Seat height from floor to sit<br />
N200 Back of the knee to the back of chair<br />
N194 Length from knee to back of chair<br />
N678 Height from floor to knee back<br />
N529 Height from floor to knee<br />
N381 Length from elbow to middle finger<br />
N507 Back Width arms outstretched in front<br />
N459 Seated hip width<br />
N859 Width thighs with knees together<br />
N775 Leg length<br />
N777 Foot width<br />
N776 High instep<br />
Was measured at 200 and will be an analysis of data from the 200 people using the<br />
spreadsheet Excel, the result will reflect the percentiles 5%, 50% and 95%, the maximum and<br />
minimum of each measurements.<br />
3. ANALYSIS OF RESULTS<br />
The results of research carried out in each of the measurements are shown in the tables or charts<br />
anthropometric working population of Caborca, Sonora, as follows:<br />
Table 1 shows the total data by age group and sex in years, in tables 2, 3, 4, 5, 6, 7 and 8<br />
shows the results of the analysis of the 50 measures anthropometric research by age, sex and<br />
place of origin.<br />
The tables show the calculation of the percentiles 5, 50 and 95%, and the maximum and<br />
minimum measurements. The calculations were analyzed in the Excel spreadsheet. The weight<br />
calculation is given in kilograms, the other measures are in centimeters.<br />
Table 1 Distribution of data by age group and sex.<br />
SEX<br />
AGE MEN WOMEN TOTALS<br />
18-20 69 24 93<br />
21-23 49 26 75<br />
24-27 24 8 32<br />
TOTALS 142 58 200<br />
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Table 2 Results of analysis of measures for the age ranges of 18-20 years.<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 48.6 68 93.4 40 105<br />
N805 Stature 156.8 170.5 183.4 151.1 194<br />
N328 Standing eye height to 145.3 160.2 173.6 140.5 182.4<br />
N23 Standing shoulder height 130.6 142.8 153.3 126 167.5<br />
N309 The standing elbow height 98.8 108.2 117.3 95.6 129.2<br />
N949 Standing waist height 93.6 102.5 110.4 92 121.7<br />
N398 Height standing gluteus 68.1 74 86.1 62 96.4<br />
N973 Standing tall on the wrist 75.4 83.6 90.3 71 105<br />
N265 Standing height to the middle finger 59.1 64.9 71.1 56 78.1<br />
N797 Width arms outstretched 156.6 175.1 187.2 150.7 200.7<br />
N798 Width at center chest elbows 79.3 91.5 97.2 68.3 99.4<br />
N80 Arm length from the wall 76.9 89.3 115 68.5 118<br />
N752 Distance from wall to the center of the fist 66.5 75.7 106.5 64.8 111<br />
N122 Standing shoulder width 37 43.3 48.1 34.5 54<br />
N223 Standing chest width 26.4 30.4 35 24.3 38.4<br />
N457 Standing Hip Width 31 35.4 39.8 30.3 46.7<br />
N639 Standing neck circumference 31.3 37 41.6 29.7 44<br />
N230 Standing chest circumference 81 94.5 110.2 77 117<br />
N931 Waist circumference stands 67.1 85 105.2 64.5 115.2<br />
N178 Standing hip circumference 90.3 102 117.9 84.7 127<br />
N430 Head circumference 54 57 60.5 52.5 98.4<br />
N144 Distance from ear to ear on the head 34.5 37 39.8 32.3 55<br />
N165 Face width to the height of the pins 12.9 14.4 15.7 11.7 15.9<br />
N427 Head width 14.5 15.5 16.9 12 17.9<br />
N595 Height of the chin to the top of head 20 23 25.2 18.5 25.7<br />
N441 Head length 17.5 19 20.3 16.4 20.9<br />
N420 Length of hand 16.4 18.5 19.8 16.1 21.2<br />
N656 Length of the palm 9.4 10.6 11.4 9.2 12.3<br />
N411 Width of palm 7.3 8.4 9.3 6.9 9.8<br />
N402 Grip diameter 4.2 4.8 5.6 3.5 6.5<br />
N758 Seat height sitting at the head 82 88.8 95.5 79 100.5<br />
N330 Seat height sitting in the eye 71.5 78 84.2 64.6 90.2<br />
N25 Seat height sitting shoulder 57 61.5 66.6 54.3 68.5<br />
N312 Seat height to seated elbow to 90 22 26 29 19.4 38<br />
N856 Sitting thigh-high 13.5 16 18.8 12 21<br />
N914 Seat height to the middle finger sitting 119.5 132.3 145.7 114 148.5<br />
N912 Height to the center of the cuff arms up 110.2 121.3 133.7 104.2 136.3<br />
N2FGM Height of sitting down 121.9 130 139.2 115.5 143.4<br />
N4FGM Seat height from floor to sit 37.8 42 45.6 36 47.2<br />
N200 Back of the knee to the back of chair 41 45.4 51 39.1 56.7<br />
N194 Length from knee to back of chair 53.2 59.2 66.5 48.4 72.3<br />
N678 Height from floor to knee back 37 42.3 45.4 33.5 49<br />
N529 Height from floor to knee 48.4 54.3 58.9 30.4 64.2<br />
N381 Length from elbow to middle finger 42.3 48 51.5 41.1 53<br />
N507 Back Width arms outstretched in front 37.2 42 46.9 32.7 49.9<br />
N459 Seated hip width 35.5 39.1 46.2 32 49.3<br />
N859 Width thighs with knees together 29.8 33.3 40 26.1 49.8<br />
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N775 Leg length 22.8 26 28.5 21.6 30.4<br />
N777 Foot width 8.6 9.7 10.7 8 11.2<br />
N776 High instep 6.2 8.3 10 5 12.3<br />
Table 3 Results of analysis of measures for the age ranges of 21-23 years.<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 51.7 68 106.3 47 132<br />
N805 Stature 153.5 168 181.3 148 184<br />
N328 Standing eye height to 142.2 157.5 169.8 138 174.2<br />
N23 Standing shoulder height 128 140.6 152 126 185.5<br />
N309 The standing elbow height 97 106.3 116.2 90.8 123.8<br />
N949 Standing waist height 93 100 111.3 91 116<br />
N398 Height standing gluteus 64.4 74 82.7 59 106.8<br />
N973 Standing tall on the wrist 73.6 82 92.2 69 95.3<br />
N265 Standing height to the middle finger 56.9 65 72.4 55 75.8<br />
N797 Width arms outstretched 153.7 172 186.3 152 189.6<br />
N798 Width at center chest elbows 77.9 89.2 95.6 64 98.2<br />
N80 Arm length from the wall 77.5 98 115.7 73.3 128.7<br />
N752 Distance from wall to the center of the fist 68 92 105.4 61.7 112<br />
N122 Standing shoulder width 37.4 42.8 48.3 35.5 51.1<br />
N223 Standing chest width 27.1 30.2 35.9 25.5 40<br />
N457 Standing Hip Width 32.4 35.7 43.2 30.5 45.2<br />
N639 Standing neck circumference 31 36.9 41.7 29.5 46<br />
N230 Standing chest circumference 85.9 96 118.2 83 124.5<br />
N931 Waist circumference stands 70 85 115.3 56 125.4<br />
N178 Standing hip circumference 93.9 104 125.7 91 135.5<br />
N430 Head circumference 54 56.8 59.2 53.5 61<br />
N144 Distance from ear to ear on the head 34 37 39.6 33.5 41<br />
N165 Face width to the height of the pins 12.9 14 15.8 12 16.7<br />
N427 Head width 14.1 15.5 16.5 12 16.8<br />
N595 Height of the chin to the top of head 19.5 22.2 24.8 19 25.8<br />
N441 Head length 17.4 18.9 20.5 17 24.6<br />
N420 Length of hand 16.4 18.1 19.7 15.6 20.5<br />
N656 Length of the palm 9.1 10.4 11.4 7.8 19.2<br />
N411 Width of palm 7.2 8.4 9.3 6.5 9.5<br />
N402 Grip diameter 4 4.7 5.4 3.4 5.6<br />
N758 Seat height sitting at the head 80.6 88 93.8 79 95<br />
N330 Seat height sitting in the eye 70.9 77.2 82.4 66.7 84<br />
N25 Seat height sitting shoulder 56 60.9 70.3 53.5 83<br />
N312 Seat height to seated elbow to 90 22 26 30.7 19.2 39<br />
N856 Sitting thigh-high 13.1 16 19.9 12 21.5<br />
N914 Seat height to the middle finger sitting 118.3 132.2 141 113.4 145<br />
N912 Height to the center of the cuff arms up 110 122.4 129.8 103.3 140.5<br />
N2FGM Height of sitting down 119 130 137 115.4 140<br />
N4FGM Seat height from floor to sit 37.3 41 45 36 46.5<br />
N200 Back of the knee to the back of chair 40.1 46 50.1 39.7 55<br />
N194 Length from knee to back of chair 52.7 59 64.4 51 70.5<br />
N678 Height from floor to knee back 36.6 42 46 35.5 50.9<br />
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N529 Height from floor to knee 47.3 54 58.6 43.4 65.5<br />
N381 Length from elbow to middle finger 40.9 46.6 51 40 54<br />
N507 Back Width arms outstretched in front 36.7 41.6 46.1 34 47.7<br />
N459 Seated hip width 35.5 39 46 29 54.7<br />
N859 Width thighs with knees together 30 33.5 40.2 28.4 46.8<br />
N775 Leg length 22.7 25.5 27.8 22 28.6<br />
N777 Foot width 8.4 9.8 11 8 12<br />
N776 High instep 5.9 8 9.2 5 10.5<br />
Table 4 Results of analysis of measures for the age ranges of 24-27 years.<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 57.6 74.5 108.4 50 138<br />
N805 Stature 158.9 171 183.3 156 187<br />
N328 Standing eye height to 147.3 161 169.7 132 177.6<br />
N23 Standing shoulder height 132 142.5 153.8 131 159.3<br />
N309 The standing elbow height 102.3 107.5 117.5 100.5 119<br />
N949 Standing waist height 91.3 101 109 85 113<br />
N398 Height standing gluteus 65 73 80.7 62 89<br />
N973 Standing tall on the wrist 76.1 81 92.2 68.5 92.8<br />
N265 Standing height to the middle finger 59.8 65.1 72.9 58.5 74<br />
N797 Width arms outstretched 160 174 188.2 155 193<br />
N798 Width at center chest elbows 85 91 96.3 83 99<br />
N80 Arm length from the wall 81.3 95.2 116.3 77 122.5<br />
N752 Distance from wall to the center of the fist 62.8 87.2 106.7 60 107<br />
N122 Standing shoulder width 38 44.7 49.5 36.2 52.9<br />
N223 Standing chest width 27.6 32 37.3 26.2 41.4<br />
N457 Standing Hip Width 31.6 36 44.2 31.5 76.5<br />
N639 Standing neck circumference 32.6 38 44 31 44.8<br />
N230 Standing chest circumference 86.6 98.4 117.5 85.5 150<br />
N931 Waist circumference stands 74.8 90 120 70 151.8<br />
N178 Standing hip circumference 94.6 107.2 122.9 93 149.5<br />
N430 Head circumference 54.8 57.5 60 54 60<br />
N144 Distance from ear to ear on the head 34.6 36.8 40 34 40<br />
N165 Face width to the height of the pins 12.5 14.1 16.1 11.4 16.2<br />
N427 Head width 14.4 15.3 16.7 12.4 17<br />
N595 Height of the chin to the top of head 20.9 23 27.1 20 29<br />
N441 Head length 17 19 20.2 16 20.6<br />
N420 Length of hand 17 18.6 20 17 20.1<br />
N656 Length of the palm 9.6 10.7 11.3 9.5 22<br />
N411 Width of palm 7.3 8.7 9.1 7 9.3<br />
N402 Grip diameter 4 4.9 5.6 3.8 5.8<br />
N758 Seat height sitting at the head 84.3 88.2 93.2 83 98<br />
N330 Seat height sitting in the eye 72.9 77.1 83 70 84.5<br />
N25 Seat height sitting shoulder 58 61 68.1 57 83<br />
N312 Seat height to seated elbow to 90 21.8 27.2 29.8 21 32<br />
N856 Sitting thigh-high 13.7 16.3 18.9 13 20<br />
N914 Seat height to the middle finger sitting 122.4 131.8 140.8 117.4 150<br />
N912 Height to the center of the cuff arms up 111.7 122 129.7 109.4 138<br />
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N2FGM Height of sitting down 123.6 130 137.8 121.5 139<br />
N4FGM Seat height from floor to sit 37.6 41.8 46.2 37 47<br />
N200 Back of the knee to the back of chair 41.4 45.3 49.1 40 53.5<br />
N194 Length from knee to back of chair 55.4 58.2 65 53 67.2<br />
N678 Height from floor to knee back 37.8 42.7 46.3 36 48.5<br />
N529 Height from floor to knee 50.4 55.3 61 49.5 63.2<br />
N381 Length from elbow to middle finger 43.6 47 49.5 41 50.3<br />
N507 Back Width arms outstretched in front 37.2 43 47.8 35 49.7<br />
N459 Seated hip width 36.3 39.5 48.4 36 56.4<br />
N859 Width thighs with knees together 29.3 34.6 43.8 27.5 52.6<br />
N775 Leg length 23.1 26 28.3 23 30<br />
N777 Foot width 9 9.7 11 8.7 11<br />
N776 High instep 6.1 8 10 6 10<br />
Table 5 Results of analysis of measures for female.<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 46.9 57.5 95 40 138<br />
N805 Stature 151 160 172 148 172.8<br />
N328 Standing eye height to 140.9 149.4 159.7 138 161.6<br />
N23 Standing shoulder height 126.9 133 142.4 126 147<br />
N309 The standing elbow height 96.8 102.9 109.9 94 114<br />
N949 Standing waist height 92.6 98.5 106.5 85 109<br />
N398 Height standing gluteus 66.3 72.4 80.1 61.5 82.7<br />
N973 Standing tall on the wrist 73 79.4 85.8 71 87<br />
N265 Standing height to the middle finger 56.4 62.1 68.1 56 69.9<br />
N797 Width arms outstretched 152.4 160.4 176.5 150.7 177<br />
N798 Width at center chest elbows 73.9 83.5 89.6 64 93.7<br />
N80 Arm length from the wall 75.5 81.8 106.5 73.3 114<br />
N752 Distance from wall to the center of the fist 64.7 71.7 98.9 61.7 104.5<br />
N122 Standing shoulder width 35.5 39.6 46.6 34.5 52.9<br />
N223 Standing chest width 26 29 35.4 24.3 41.4<br />
N457 Standing Hip Width 32.6 35.6 45 30.3 46.7<br />
N639 Standing neck circumference 30 33 38.2 29.5 44.8<br />
N230 Standing chest circumference 82.8 92.5 118.5 79.8 150<br />
N931 Waist circumference stands 66 77.5 112.2 64.5 151.8<br />
N178 Standing hip circumference 92.7 99.2 127.2 84.7 149.5<br />
N430 Head circumference 53.5 56 58.2 53 98.4<br />
N144 Distance from ear to ear on the head 33.9 36 38.7 33 39<br />
N165 Face width to the height of the pins 12.3 13.5 15.1 11.4 15.8<br />
N427 Head width 14.2 15.1 16.2 12 17.9<br />
N595 Height of the chin to the top of head 19 22 24.2 18.5 29<br />
N441 Head length 17.1 18.5 20 16.4 20.3<br />
N420 Length of hand 16.1 17.5 18.9 15.6 19.4<br />
N656 Length of the palm 9 9.7 11.2 7.8 19.2<br />
N411 Width of palm 7 7.5 8.5 6.5 9.3<br />
N402 Grip diameter 3.9 4.5 5 3.5 5.6<br />
N758 Seat height sitting at the head 79.5 85 89.4 79 93<br />
N330 Seat height sitting in the eye 69.8 74.1 78.3 66.3 81.7<br />
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N25 Seat height sitting shoulder 55.8 59 63.5 53.5 69<br />
N312 Seat height to seated elbow to 90 22 26.6 29.6 20.5 39<br />
N856 Sitting thigh-high 12.6 15.2 18.7 12 21.5<br />
N914 Seat height to the middle finger sitting 114.9 123.7 133.1 113.4 135<br />
N912 Height to the center of the cuff arms up 108 115 122.5 103.3 127.7<br />
N2FGM Height of sitting down 117 124.8 131.1 115.4 134.1<br />
N4FGM Seat height from floor to sit 37 39.2 44 36 45.1<br />
N200 Back of the knee to the back of chair 40 44 49 39.1 49.2<br />
N194 Length from knee to back of chair 51 56.9 61.4 48.4 65.4<br />
N678 Height from floor to knee back 36 38.9 43.1 35.5 44<br />
N529 Height from floor to knee 46.6 51.1 55.3 30.4 56<br />
N381 Length from elbow to middle finger 40.7 44 47 40 49.1<br />
N507 Back Width arms outstretched in front 35.5 39.9 43.6 33 48.6<br />
N459 Seated hip width 35.1 39 49.2 32.7 56.4<br />
N859 Width thighs with knees together 30 33.7 42.8 28.5 52.6<br />
N775 Leg length 22 23.8 25.1 21.6 27.2<br />
N777 Foot width 8.1 9 10 8 10.3<br />
N776 High instep 6 7.7 9 5 9.7<br />
Table 6 Results of analysis of measures for male.<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 57.1 73 100.9 49 132<br />
N805 Stature 163 172 183.8 156.7 194<br />
N328 Standing eye height to 151 161.5 174 132 182.4<br />
N23 Standing shoulder height 135.2 144.2 153.5 132 185.5<br />
N309 The standing elbow height 102 109.7 118 90.8 129.2<br />
N949 Standing waist height 94.1 103 111.4 91 121.7<br />
N398 Height standing gluteus 65 74.7 88.6 59 106.8<br />
N973 Standing tall on the wrist 76 84 92.5 68.5 105<br />
N265 Standing height to the middle finger 59 66 73.4 55 78.1<br />
N797 Width arms outstretched 166 177.4 189.2 160.5 200.7<br />
N798 Width at center chest elbows 86.3 92.1 97.5 68.3 99.4<br />
N80 Arm length from the wall 84.2 93 116.6 68.5 128.7<br />
N752 Distance from wall to the center of the fist 72 79.8 107 60 112<br />
N122 Standing shoulder width 41 44.6 49.3 36.6 54<br />
N223 Standing chest width 28 31 36.4 25.7 40<br />
N457 Standing Hip Width 31.5 35.6 39.2 30.3 76.5<br />
N639 Standing neck circumference 34 37.9 42.5 32.8 46<br />
N230 Standing chest circumference 85.1 96.5 116.3 77 124.4<br />
N931 Waist circumference stands 73.1 87 111.4 56 126<br />
N178 Standing hip circumference 94 104 117.8 87 135.5<br />
N430 Head circumference 54 57 60 52.5 86.5<br />
N144 Distance from ear to ear on the head 34.5 37 40 32.3 55<br />
N165 Face width to the height of the pins 13 14.5 16 12.5 16.7<br />
N427 Head width 14.5 15.6 16.6 12.4 17.7<br />
N595 Height of the chin to the top of head 20.5 23 25.4 18.9 28.8<br />
N441 Head length 17.5 19 20.6 16 24.6<br />
N420 Length of hand 17.4 18.8 20 17 21.2<br />
N656 Length of the palm 10 10.7 11.4 9.5 22<br />
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N411 Width of palm 7.9 8.7 9.3 7.5 9.8<br />
N402 Grip diameter 4.1 4.9 5.6 3.4 6.5<br />
N758 Seat height sitting at the head 84 89.6 95.1 81 100.5<br />
N330 Seat height sitting in the eye 73 79 84 64.6 90.2<br />
N25 Seat height sitting shoulder 58 62 67.5 56 83<br />
N312 Seat height to seated elbow to 90 22 26 29.5 19.2 32<br />
N856 Sitting thigh-high 14 16.4 19.4 12.4 21<br />
N914 Seat height to the middle finger sitting 127.2 134.3 145 119 150<br />
N912 Height to the center of the cuff arms up 117 124 134 111.5 140.5<br />
N2FGM Height of sitting down 123.6 131.5 139 120.4 143.4<br />
N4FGM Seat height from floor to sit 38.5 42.3 46 36.5 47.2<br />
N200 Back of the knee to the back of chair 42 46 51.2 40 56.7<br />
N194 Length from knee to back of chair 55.7 60 66 52 72.3<br />
N678 Height from floor to knee back 39.2 43 46.7 33.5 50.9<br />
N529 Height from floor to knee 52.4 55.5 60.2 50.4 65.5<br />
N381 Length from elbow to middle finger 45 48 51.5 41.6 54<br />
N507 Back Width arms outstretched in front 38.4 43 47.2 32.7 49.9<br />
N459 Seated hip width 35.7 39.2 46 29 54.7<br />
N859 Width thighs with knees together 29.7 33.6 41.5 26.1 49.8<br />
N775 Leg length 24.7 26.4 28.6 24 30.4<br />
N777 Foot width 9 10 11 8.5 12<br />
N776 High instep 6 8.3 10 5 12.3<br />
Table 7 Results of analysis of measures for Caborca people<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 50 69 100.9 40 138<br />
N805 Stature 155.1 169.1 183 148 194<br />
N328 Standing eye height to 143.3 158.4 173.2 132 182.4<br />
N23 Standing shoulder height 130.1 141.6 152.9 126 185.5<br />
N309 The standing elbow height 98 107.1 117.4 90.8 129.2<br />
N949 Standing waist height 93 101.5 110.5 85 121.7<br />
N398 Height standing gluteus 65.1 74 85.5 59 106.8<br />
N973 Standing tall on the wrist 75 82.5 92 68.5 105<br />
N265 Standing height to the middle finger 58 64.9 72.6 55 78.1<br />
N797 Width arms outstretched 155.1 174 187.6 150.7 200.7<br />
N798 Width at center chest elbows 79 90.2 97.3 64 99.4<br />
N80 Arm length from the wall 77.3 91.3 115.2 68.5 128.7<br />
N752 Distance from wall to the center of the fist 66.2 78.9 106.7 60 112<br />
N122 Standing shoulder width 37 43.2 48.5 34.5 54<br />
N223 Standing chest width 26.8 30.7 36.8 24.3 41.4<br />
N457 Standing Hip Width 31.6 35.6 42.5 30.3 76.5<br />
N639 Standing neck circumference 31 37 42 29.5 46<br />
N230 Standing chest circumference 84 95.9 117 77 150<br />
N931 Waist circumference stands 68.1 85.2 112 56 151.8<br />
N178 Standing hip circumference 93 103.3 121 84.7 149.5<br />
N430 Head circumference 54 57 60 52.5 98.4<br />
N144 Distance from ear to ear on the head 34 37 40 32.3 55<br />
N165 Face width to the height of the pins 12.9 14.2 15.9 11.4 16.7<br />
N427 Head width 14.5 15.4 16.6 12 17.9<br />
N595 Height of the chin to the top of head 19.6 22.8 25.4 18.5 29<br />
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N441 Head length 17.3 19 20.4 16 24.6<br />
N420 Length of hand 16.5 18.4 19.8 15.6 21.2<br />
N656 Length of the palm 9.3 10.5 11.4 7.8 22<br />
N411 Width of palm 7.2 8.5 9.3 6.5 9.8<br />
N402 Grip diameter 4 4.7 5.5 3.4 6.5<br />
N758 Seat height sitting at the head 82 88.3 95 79 100.5<br />
N330 Seat height sitting in the eye 71 77.4 83.7 64.6 90.2<br />
N25 Seat height sitting shoulder 56.8 61 67.3 54.3 83<br />
N312 Seat height to seated elbow to 90 22 26.3 29.5 19.2 39<br />
N856 Sitting thigh-high 13.1 16 19.4 12 21.5<br />
N914 Seat height to the middle finger sitting 119 132 142.4 113.4 150<br />
N912 Height to the center of the cuff arms up 110 121.8 131.9 103.3 140.5<br />
N2FGM Height of sitting down 121 130 138.9 115.4 143.4<br />
N4FGM Seat height from floor to sit 37.6 41.6 46 36 47.2<br />
N200 Back of the knee to the back of chair 40.5 45.3 51 39.1 56.7<br />
N194 Length from knee to back of chair 53 59 65.5 48.4 72.3<br />
N678 Height from floor to knee back 36.7 42.1 46 33.5 50.9<br />
N529 Height from floor to knee 48.5 54.5 59.9 30.4 65.5<br />
N381 Length from elbow to middle finger 42 47 51.4 40 54<br />
N507 Back Width arms outstretched in front 37 42 47.1 32.7 49.9<br />
N459 Seated hip width 35.5 39.1 46.5 29 56.4<br />
N859 Width thighs with knees together 29.8 33.6 42.1 26.1 52.6<br />
N775 Leg length 22.9 25.9 28.4 21.6 30.4<br />
N777 Foot width 8.5 9.8 11 8 12<br />
N776 High instep 6 8 10 5 12.3<br />
Table 8 Results of analysis of measures for Caborca not native people.<br />
Percentile<br />
Code Name of the measure 5% 50% 95% MIN MAX<br />
N920 Weight 50.3 68.0 89.7 46.0 105.0<br />
N805 Stature 154.2 171.7 180.2 150.6 184.2<br />
N328 Standing eye height to 144.3 161.0 170.8 143.0 175.0<br />
N23 Standing shoulder height 128.6 144.2 152.5 128.1 155.0<br />
N309 The standing elbow height 97.3 111.5 114.5 97.0 117.0<br />
N949 Standing waist height 92.6 101.8 111.5 92.4 114.0<br />
N398 Height standing gluteus 66.9 73.1 83.2 61.5 84.0<br />
N973 Standing tall on the wrist 75.0 84.7 89.2 73.0 90.0<br />
N265 Standing height to the middle finger 58.1 65.4 70.6 58.0 71.0<br />
N797 Width arms outstretched 153.7 174.3 186.2 152.0 187.0<br />
N798 Width at center chest elbows 77.0 91.3 94.7 74.3 95.0<br />
N80 Arm length from the wall 76.0 92.7 116.2 73.3 117.0<br />
N752 Distance from wall to the center of the fist 66.2 78.3 105.3 63.1 107.0<br />
N122 Standing shoulder width 37.5 43.8 48.3 35.7 49.8<br />
N223 Standing chest width 27.0 29.9 35.2 26.6 36.4<br />
N457 Standing Hip Width 31.8 35.6 37.2 30.5 38.1<br />
N639 Standing neck circumference 31.9 36.5 39.8 31.0 44.0<br />
N230 Standing chest circumference 86.6 95.0 113.6 84.0 117.0<br />
N931 Waist circumference stands 73.8 85.2 109.1 70.0 115.2<br />
N178 Standing hip circumference 94.4 101.8 112.9 91.0 117.8<br />
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N430 Head circumference 53.9 56.0 57.7 53.5 59.0<br />
N144 Distance from ear to ear on the head 33.9 36.0 39.2 33.5 40.0<br />
N165 Face width to the height of the pins 12.4 14.3 15.2 12.3 15.9<br />
N427 Head width 14.2 15.7 16.6 14.0 17.3<br />
N595 Height of the chin to the top of head 19.9 23.0 25.0 19.4 25.3<br />
N441 Head length 17.3 18.2 19.1 17.0 19.2<br />
N420 Length of hand 16.5 18.1 20.0 16.3 20.1<br />
N656 Length of the palm 9.4 10.5 12.7 9.4 19.2<br />
N411 Width of palm 7.4 8.5 9.3 7.3 9.3<br />
N402 Grip diameter 4.1 4.9 5.6 3.9 6.4<br />
N758 Seat height sitting at the head 82.0 89.0 92.7 79.0 95.2<br />
N330 Seat height sitting in the eye 72.7 78.5 82.1 69.0 82.6<br />
N25 Seat height sitting shoulder 57.3 61.7 68.6 53.5 83.0<br />
N312 Seat height to seated elbow to 90 22.2 25.5 28.7 22.0 29.6<br />
N856 Sitting thigh-high 14.2 16.2 18.3 13.7 19.8<br />
N914 Seat height to the middle finger sitting 119.5 132.6 141.0 116.6 146.5<br />
N912 Height to the center of the cuff arms up 112.9 122.8 130.1 107.8 136.3<br />
N2FGM Height of sitting down 120.5 130.0 137.7 117.5 141.4<br />
N4FGM Seat height from floor to sit 37.1 41.0 45.3 36.5 45.3<br />
N200 Back of the knee to the back of chair 41.9 46.1 49.0 41.0 49.2<br />
N194 Length from knee to back of chair 54.3 60.9 63.2 52.5 64.0<br />
N678 Height from floor to knee back 36.9 41.9 45.0 36.6 45.0<br />
N529 Height from floor to knee 47.3 54.2 58.2 47.0 58.5<br />
N381 Length from elbow to middle finger 41.5 46.5 49.7 40.7 50.6<br />
N507 Back Width arms outstretched in front 36.9 42.9 45.1 36.1 45.3<br />
N459 Seated hip width 36.9 38.2 45.2 36.6 46.2<br />
N859 Width thighs with knees together 30.9 33.6 37.9 30.0 42.8<br />
N775 Leg length 22.5 25.7 28.0 21.8 28.3<br />
N777 Foot width 8.4 9.8 10.7 8.3 11.0<br />
N776 High instep 6.9 8.1 9.4 6.3 9.9<br />
4. CONCLUSIONS AND RECOMMENDATIONS<br />
Working conditions are an important issue, so it should be taken into account when<br />
designing a workspace, thereby, the worker will feel more comfortable and secure and will result<br />
in higher productivity, lower absenteeism, fewer accidents, lower turnover, etc. To achieve this it is<br />
necessary to design each station or place of work according to the needs of the population that<br />
will occupy this space, this implies knowing the dimensions of the population, if not known, it can<br />
hardly meet the target, however when known, can have an assurance that the highest percentage<br />
of people who use the work area, will have no problems in terms of size and awkward postures.<br />
By creating a product would be recommended to be used without problem by the largest<br />
number of users. The reality is that many products do not have the ability to adapt to 100% of<br />
users. For this you can follow two paths, the first would make products of various sizes in such a<br />
way that takes the opportunity to choose the one that best suits the needs of the user, the other<br />
would be to create products that are adjustable over a range measures, making it necessary to<br />
know the cost-benefits so that decision making is correct. The selection of some of the<br />
alternatives mentioned above would be facilitated if known anthropometric dimensions of the<br />
population that is expected to address. From the above highlights the importance of the results of<br />
this research.<br />
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From this research were obtained anthropometric records or letters of the working<br />
population of the city of Caborca, Sonora, Mexico, in the age ranges from 18 to 20, 21 to 23 and<br />
24 to 27 years, and the letter Anthropometric women and men, those from Caborca and not<br />
originating in Caborca. These letters reflect the measures of the population having an age range<br />
from 18 to 27 years, within which 71% are men and 29% are women, 91% are from Caborca and<br />
9% do not originate in Caborca.<br />
It is hoped that this research is another step towards the creation of anthropometric letters<br />
of the Mexican population, as currently there are very few records are.<br />
At the end of the investigation we can see the importance of the study of ergonomics<br />
and especially one of its branches which is the anthropometry, which is responsible for examining<br />
each of the different measures that make up the human body. Knowing these measures can be<br />
designed with a higher degree of reliability workstations, tools and equipment, safety equipment,<br />
clothing, etc. so we can give each user a more convenient and comfortable life.<br />
The recommendations can be made once this investigation is that it would be very<br />
interesting and important to continue to obtain anthropometric records of the total Mexican<br />
population, in order to develop equipment, workstations, tools and equipment as well as<br />
everything that needs dimensions of people, especially for the Mexican people and not have to<br />
take the actions of other countries and make adjustments later.<br />
5. BIBLIOGRAPHY<br />
Annis 1996 James F. Annis. Aging effects on anthropometric dimensions important to workplace design.<br />
Annis Consulting, 503 Xenia Avenue, Yellow Springs, OH 45387, USA. International Journal of Industrial Ergonomics<br />
18 (1996) 381 – 388.<br />
Baustista 2006 Ruben Bautista Balderas. Tablas antropométricas de adultos con enanismo de entre 18 a 45 años de<br />
edad para el diseño de mobiliario. Encuentro Universitario de Ergonomía. México, D.F., México 10 y 11 de Noviembre<br />
de 2006. Consultado en Diciembre del 2006. http://www.semac.org.mx/congreso/Encuentro5-4.pdf.<br />
Cavassa 2004 César Ramírez Cavassa. Ergonomía y Productividad. Editorial LIMUSA. ISBN 968-18-3797-5.<br />
Mexico, D.F. 2004.<br />
De la Vega 2004 Enrique de la Vega. La investigación de la Ergonomia en Mexico. VI CONGRESO<br />
INTERNACIONAL <strong>DE</strong> <strong>ERGONOMÍA</strong>. Guanajuato, Guanajuato, México 26 al 29 de Mayo de 2004. Consultado en<br />
Diciembre del 2006 http://www.semac.org.mx/congreso/6-6.pdf.<br />
Gosseens 1998 R.H.M. Goossens, C.J. Snijders, y T. Fransen. Biomechanical analysis of the dimensions of pilot<br />
seats in civil aircraft. Department of Product and Systems Ergonomics, Faculty of Industrial Design Engineering, Delft<br />
University of Technology, Jawalaan 9, 2628 BX Delft, The Netherlands. Department of Biomedical Physics and<br />
Technology, Faculty of Medicine and Allied Health Sciences, Erasmus University Rotterdam, The Netherlands.<br />
Applied Ergonomics 31 (2000) 9-14. 1998.<br />
Jung 2005 Hwa S.Jung. A prototype of an adjustable table and an adjustable chair for schools.<br />
Department of Industrial Engineering, Dongshin University, 252 Daehodong, Naju, Chonnam 520-714, Republic of<br />
Korea. International Journal of Industrial Ergonomics 35 (2005) 955–969.<br />
Konz 1999: Stephan Konz. Diseño de sistemas de trabajo. Editorial Limusa. 1999. ISBN 968-18-1653-6.<br />
Maldonado 2003 Araceli Maldonado, Gilberto Mota, Juan Carlos Cano, Humberto Ponce y Sergio Chávez.<br />
Rediseño de estaciones de trabajo “secado de arcilla”. V CONGRESO INTERNACIONAL <strong>DE</strong> <strong>ERGONOMÍA</strong>. Ciudad<br />
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Juárez, Chihuahua, México. Mayo 2003. Consultado en Diciembre del 2006 http://www.semac.org.mx/congreso/5-<br />
12.pdf.<br />
Martínez 2000 Guillermo Martínez de la Teja. DISEÑO ERGONÓMICO PARA ESTACIONES <strong>DE</strong> TRABAJO CON<br />
COMPUTADORAS. II CONGRESO INTERNACIONAL <strong>DE</strong> <strong>ERGONOMÍA</strong>. Ciudad Juárez, Chihuahua, México. Mayo<br />
2000. Consultado en Diciembre del 2006 http://www.semac.org.mx/congreso/2-4.pdf.<br />
Mohammad 2005: Yunis A.A. Mohammad. Anthropometric characteristics of the hand based on laterality and<br />
sex among Jordanian. Industrial Engineering, Faculty of Engineering, King Khalid University, Abha. Elsevier.<br />
International Journal of Industrial Ergonomics 35 (2005) 747–754<br />
NASA 1978: NASA (National Aeronautics and Space Administration), 1978. Anthropology Research Project 1978<br />
Anthropometric Source Book, Vol. I: Anthropometry for Designers, NASA Reference Publication 1024' Webb<br />
Associates (Ed.). National Aeronautics and Space Administration Scientific and Technical Information Office,<br />
Houston, Texas, USA.<br />
Niebel 2001: Benjamín Niebel y Andris Freivalds. Ingeniería Industrial. Métodos, estándares y diseño de trabajo.<br />
Editorial Alfaomega. 2001. ISBN970-15-0597-2.<br />
Park, Kim 1997: Se Jin Park, Soo Chan Park, Jin Ho Kim, Chae-Bogk Kim. Biomechanical parameters on<br />
body segments of Korean adults. Ergonomics Research Group, Korea Research Institute of Standards and Science.<br />
Department of Technology Education, Korea National University of Education. Elsevier. International Journal of<br />
Industrial Ergonomics 23 (1999) 23-31.<br />
Panagiotopoulou 2003 Georgia Panagiotopoulou, Kosmas Christoulas, Anthoula Papanckolaou, Konstantinos<br />
Mandroukas. Classroom furniture dimensions and anthropometric measures in primary school. Ergophysiology<br />
Laboratory, Department of Physical Education and Sports Science, Aristotle University of Thessaloniki, Thessaloniki<br />
62100, Greece. Applied Ergonomics 35 (2004) 121–128. 2004.<br />
Reeder 2003: Kevin Reeder. Addressing Anthropometrics through dimensional figure drawing. The Technology<br />
Teacher 63 no3 14-16 N 2003.<br />
Sánchez 2002 David Sánchez Monroy. Implantación de un proceso ergonómico para la industria para control de<br />
lesiones musculoesqueleticas. IV CONGRESO INTERNACIONAL <strong>DE</strong> <strong>ERGONOMÍA</strong>. Ciudad Juárez, Chihuahua,<br />
México. Mayo 2002. Consultado en Diciembre del 2006 . http://www.semac.org.mx/congreso/4-5.pdf.<br />
Secretaria 2002: Secretaria de Salud. Manual de Procedimientos: Toma de Medidas Clínicas y<br />
Antropométricas En el Adulto y Adulto Mayor. Subsecretaría de Prevención y Protección de la Salud. Centro<br />
Nacional de Vigilancia Epidemiológica Programa de Salud del Adulto y el Anciano. México 2002.<br />
Serrano 2004: Carlos Serrano Sánchez. La antropometría de Daniel Vergara Lope. Valorar con parámetros propios.<br />
Gaceta Médica Mexicana Vol. 140 No. 4, 2004.Academia Nacional de Medicina de México, A.C.<br />
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Biomechanical model to estimate recovery time on highly repetitive work in<br />
maquila operations<br />
Fco. Octavio López Millán 1 , Enrique Javier de la Vega Bustillos 1 ,<br />
Manuel Arnoldo Rodríguez Medina 2 , Armando Ayala Corona 3<br />
1 Departamento de Ingeniería Industrial.<br />
Instituto Tecnológico de Hermosillo. Ave. Tecnológico S.N.<br />
Hermosillo, Sonora, Mx. 83170<br />
Author’s e-mail: lopezoctavio@yahoo.com.mx<br />
2 Departamento de Ingeniería Industrial.<br />
Instituto Tecnológico de Cd. Juárez. Ave. Tecnológico 1340<br />
Cd. JuárezChih, Sonora, Mx. 32500<br />
3 Departamento de Ingeniería Industrial y de Sistemas<br />
Universidad del Valle de México. Blvd. Enrique Mazón No. 617.<br />
Hermosillo, Sonora, Mx. 83165<br />
Resumen: El propósito de este trabajo es desarrollar un modelo biomecánico que permita hacer<br />
estimaciones de los tiempos de recuperación, basado en un número importante de variables<br />
obtenidas de condiciones de trabajo reales, donde, el mismo grupo de músculos está expuestoal<br />
trabajo repetitivo y a bajos esfuerzos. Las variables independientes están relacionadas con las<br />
características de los trabajadores y del trabajo. Las variables de respuesta son el tiempo de<br />
recuperación y la fatiga percibida. Los datos se obtuvieron de industrias maquiladoras del<br />
noroeste de México.<br />
Palabras clave: Modelo biomecánico, trabajo repetitivo, maquiladora<br />
Abstract: The purpose of this research is development a biomechanical model allowing<br />
estimating the recovery time based on an important number of variables, obtained from real work<br />
conditions, where the same muscle group is exposed to repetitive work and low efforts.<br />
Independent variables are related to personal characteristics and work characteristics. Response<br />
variable are recovery time and perceived fatigue. Data were obtained from workers and work<br />
stations from Maquila industries in northwest Mexico. The research is based on considerations<br />
about anthropometrics from a Mexican population, genre and hour of work.<br />
Keywords: Biomechanical modeling, repetitive work, cumulative effect of force, maquila<br />
1. Introduction.<br />
Assessment of human work has been a fundamental element on the ergonomics evolution,<br />
actually there is a wide variety of methods for the ergonomics assessment of work stations,<br />
however, at the moment that the ergonomist needs a tool, sometimes there is the constraint which<br />
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results usually shows the most risky condition, in terms of a work muscle skeletal disorder, it<br />
means that shows a value qualifying a single moment of work, while the work remains continuous<br />
along the journey.<br />
The work doing by the hands has been a very important factor on manufacturing industries,<br />
especially on development countries, but the human being and its physical characteristics at<br />
service of material transformation trough industrial process it is not an endless power supply,<br />
while time pass away, physical performance could be affected and modified.<br />
As a result of frequent exposure to work there is a risk of musculoskeletal injuries, Bernard et al<br />
(1997) refers that it´s “were recognized as having occupational etiologic factors as early as the<br />
beginning of the 18th century. However, it was not until the 1970s that occupational factors were<br />
examined using epidemiologic methods, and the work-relatedness of these conditions began<br />
appearing regularly in the international scientific literature. Since then the literature has increased<br />
dramatically; more than six thousand scientific articles addressing ergonomics in the workplace<br />
have been published. Yet, the relationship between MSDs and work-related factors remains the<br />
subject of considerable debate.”<br />
Continuous and repetitive tasks could lead to disorders on the soft tissues on joints. The tissues<br />
that frequently get injured as a result of exposure to occupational biomechanical hazards are<br />
ligaments, tendons and muscles. Other structures affected less frequently are cartilage and<br />
bones. All biological tissues are visco-elastic; hence, their mechanical properties are time- and<br />
strain rate-dependent. The tissue visco-elastic property determines the duration required for<br />
complete mechanical recovery, Kumar (2001).<br />
Disorders on the soft tissues are well known as cumulative trauma disorders (CTD´s), it´s<br />
basically a combination of factors or occupational activities that leads to these injuries, Keyserling<br />
et al (1993) includes repetitive motions, forceful exertions, and awkward postures. Bernard et al<br />
(1997) presents an evaluation and summary of the epidemiologic evidence focuses on disorders<br />
affecting the neck and the upper extremity; including tension neck syndrome, shoulder tendinitis,<br />
epicondylitis, carpal tunnel syndrome, and hand-arm vibration syndrome, which have been the<br />
most extensivelystudied in the epidemiologic literature. Combination of these risk factors on the<br />
same activities increases the possibility of injuries in wrist and shoulder while neck disorders are<br />
related to awkward posture, for instance.<br />
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CTD´s cost days and money so there are relevant, the BLS (2005) reports 1,234,700 workdays<br />
lost in USA. In the same year there were 270,890 reported injuries in low back. Bernard et al<br />
(1997) reports 32% of injuries were due to excessive efforts or repetitive tasks. In specific, 65% of<br />
cases were caused by effort to lifts objects or materials, affecting low back, 52% were caused by<br />
pushing or pulling. But it´s not only low back injuries, the report includes 47,681 shoulder injuries<br />
and 92,576 injuries associated to repetitive movements, 55% of that affected wrist.<br />
Muggleton et al (1999) refers to injuries related to work as typical injuries on XX century and<br />
consider it´s as the bigger of problems on occupational wealth. On United Kingdom, upper limb<br />
musculoskeletal disorders are the most frequent just below low back pain injuries. CTD external<br />
causes says, are related with the pressure on industry business for increasing productivity. In<br />
consequence, costs for; medical attention, incapacities days, lost workdays, employs rotation,<br />
absenteeism costs, have been increased too.<br />
Viikari-Juntura (1997), notes the need of programs and strategies to prevent occupational<br />
injurieswhile lost days increases on industrial countries, as well as development countries. The<br />
European Union is working on rules and laws about occupational injuries, focusing in harmonizing<br />
it´s legislation.<br />
In México, according to the IMSS (Mexican Institute for the Social Safety) in 2006 were reported<br />
138,700 work injuries in hand-wrist and low back area. The Mexican legislation and rules doesn´t<br />
make any difference between accident and occupational injuries.<br />
In northern México, in Border States the data are the follows:<br />
Table 1. Work related injuries in Nothern Mexico..<br />
State Injuries Hand-wrist Low back<br />
Nuevo León 29054 10425 3264<br />
Baja California 16308 6025 2041<br />
Sonora 12074 3678 2127<br />
Tamaulipas 11823 3691 1734<br />
Chihuahua 1762 453 239<br />
Coahuila 1425 358 149<br />
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1.1 Occupational injuries. The risk factors are related with injuries in joints and soft tissues.<br />
There are several terms to name it, Grieco et al (1998) defines as “Work Musculoskeletal<br />
Disorders; WMSD”, but frequently is used as a synonymous “Cumulative Trauma Disorders<br />
(CTD´s)” or “Repetitive Strain Injuries (RSI)”. Grieco et al (1998) associate as characteristics of<br />
these injuries the follows: Its origin is due to several factors (occupational and personal), it take<br />
long time to develop the disorder, recovery are used to be slow and probably never at 100%,<br />
frequently involves groups of tendons and muscles and that one’s caused by nerves pressed are<br />
de lesser frequents but the painful and costly.<br />
1.2 Ergonomic Risk Factors. To understand the musculoskeletal disorders problem, is required<br />
to identify the risk factors associated to these kinds of injuries. There is a wide literature about it<br />
and its don´t surprise, the problem has been studied for years and many point of views and results<br />
of research converge on the causes or risk factors, Colombini (1998) recognize mainly four risk<br />
factors; repetitive movements (frequency), force applied to the task, awkward postures and lack of<br />
enough recovery time on each work cycle. Muggleton (1999) includes vibration as a risk factor for<br />
the hand-wrist. McAtamney y Corlet (1973) refers to the risk factors as external factors, including<br />
a consideration for static work load on muscles. Furthermore, highly repetitive work may directly<br />
damage tendons through repeated stretching and elongation, as well as increase the likelihood of<br />
fatigue and decrease the opportunity for tissues to recover Keyserlin et al (1993).<br />
The focus of this project is on the repetitive effect on recovery time based on manufacturing<br />
activities at high level of repetition which is the most of the tasks that operators perform on<br />
maquila industries in basically all Northern of México.<br />
Is well known the wide ergonomics assessment techniques available in present, Liand Buckle<br />
(1999) mentioned that exposure to risks for potential work-related musculoskeletal injuries has<br />
been assessed using a variety of methods, including pen and paper based observation methods,<br />
videotaping and computer-aided analysis, direct or instrumental techniques, and various<br />
approaches to self-report assessment.<br />
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The purpose of this research is develop a model to describe the effect of repetitive task and<br />
predict the recovery time for continuous task and includes subjective factors as perceived fatigue,<br />
this last factor in order to explain the presence of tape on finger tips or wrist protections.<br />
2. Method.<br />
It is very relevant to the success of this project obtain the data from real conditions, that means<br />
going to the assembly production lines on maquilas and get the data. The first step consists<br />
tochoose the work stations, video recorder it, get data: anthropometric and operational and<br />
perceived fatigue.<br />
We appreciate the support from the maquila, they let Us to see the process, mostly of it is<br />
confidential, for the first step 23 workstations were analyzed, the variables included are; height,<br />
weight, angle on shoulder (RH) to perform a sustained effort and the time on that posture.<br />
Additionally, a perceived fatigue questionnaire was ask to answer for, it qualifies from 0 to 3<br />
presences of any symptoms like numbness, pain or stiffness, were 0 means no symptom at the<br />
end of the work shift, 1 means seldom times remember any symptom, 2 is related to occasionally<br />
feels any symptom and 3 are related to frequent symptoms. For each workstation were<br />
considered two activities involving shoulder posture.<br />
On second step data were analyzed using 3D SSPP© and Rohmert formula to estimate<br />
recuperation time for each operator. The third step involves the linear regression analysis and the<br />
Bayesian approach to optimize the time recuperation model. WinBUGS is the tool for Bayesian.<br />
3. Results<br />
All collected data are at the end, summarizing, 46 data were analyzed for the 23 operators; it’s<br />
due to the use of two different exertion times. On each job the angle on shoulder was measured<br />
and every workstation was modeled using the 3D SSPP© software to obtain the moment on the<br />
shoulder. Moment and sustained effort time on seconds were used to introduce as data to<br />
Rohmert formula, the result is the recovery time for the shoulder, expressed on seconds on<br />
different posture, for every 60 seconds of work.<br />
3.1 Statistical analysis. The analysis was made using SPSS© software. In the beginning, the<br />
moment on shoulder was considered as a variable, it’s give an excellent correlation r = .918 with<br />
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an adjust r = .819 which means a high explanation to the variability of the data, but moment on the<br />
practice is not an easy data to calculate, that´s why we optioned a less efficient model but easy to<br />
use and understand.<br />
Subtracting the moment the model summary is:<br />
The linear regression model obtained is shown as follows:<br />
Coefficients a<br />
Model<br />
UnstandardizedCoefficients<br />
B Std. Error Beta<br />
StandardizedCo<br />
efficients<br />
t Sig.<br />
1 (Constant) -28.025 29.563 -.948 .348<br />
Estatura .220 19.919 .001 .011 .991<br />
Peso -.115 .079 -.133 -1.454 .153<br />
Angulo .466 .082 .436 5.684 .000<br />
FatPer 1.068 1.097 .077 .974 .335<br />
TESF 1.208 .128 .716 9.451 .000<br />
a. Dependent Variable: TREC<br />
Expressed on the mathematical form, the model is:<br />
Recovery Time= -28.025 + .22*Height - .115*Weight + .466*Angle + 1.068*Perceived Fatigue<br />
+ 1.208*Sustained effort time<br />
3.2 Bayesian Analysis.The Bayesian analysis is included in order to optimize the linear<br />
regression model coefficients, on this approach; coefficients leave the parameter condition in the<br />
model becoming a variable on the model. WinBUGS is a tool developed to perform Bayesian,<br />
based on Markov Chain and Monte Carlo methods the software allows simulate a great number of<br />
repetitions.<br />
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There are some additional considerations to made; variables fit a normal distribution. On every<br />
variable the software run more than 10,000 iterations.<br />
The linear regression model has change as follows:<br />
Recovery Time= -44.13+ 5.22*Height -0.1227*Weight + 0.5464*Angle -0.02*Perceived Fatigue<br />
+ 1.534*Sustained effort time<br />
The resulting model is based on the original linear regression model but coefficients become<br />
variables with its own statistical distribution.<br />
Bayesian analysis is a very useful tool when experiments are limited and especially when the data<br />
come from human characteristics and a cross functional approach are used on the research.<br />
4. Discussion<br />
The linear regression model optimized can now be used to estimate recovery times on repetitive<br />
operations but is necessary draw some limitations; to verify the accuracy of the model it was run<br />
with different exertion times, the model result on negative values for recovery time when the<br />
exertion timeis below 10 seconds and for exertion times higher than 30 seconds results are<br />
considerably greater that could made efficient on process get on low values, so it has and impact<br />
on costs.<br />
In test stage, when exertion times are below 10 seconds, recovery time calculated by Rohmert<br />
formula result on values around 2 seconds or lower, that could be interpreted like low risk<br />
operations due to repetitiveness and classifieds on green codes. On the other hand exertion time<br />
over 30 seconds results on high repetition rates having an effect on sustain effort and<br />
consequently on a high risk for an occurrence of occupational injuries.<br />
The application of the model is not complicated, the input variables are the predictors variables;<br />
the height is expressed on meters, the weight is in kilograms, the angle on the shoulder can be<br />
measured using a goniometer, perceived fatigue could be get asking to the operators for the<br />
presence of any symptom described before and exertion time can be measured by a chronometer<br />
or analyzing the video time counter. Once the data are collected, introduce it in the formula and<br />
the results are expressed on how many seconds per every 60 seconds cycle are needed to<br />
recover a group of muscles from fatigue due to the job.<br />
The application of the model could be extensive on a future to other groups of muscles, for<br />
instance low back muscles or wrist articulation, increasing the focus of the research, increasing<br />
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the analysis of different jobs when those are repetitive. At the end the final purpose is bringing a<br />
little more on safety on daily performance allowing to people return home with a little bit more<br />
energy to share with the family.<br />
References<br />
Bernard, B. (1997). “Musculoskeletal Disorders and Workplace Factors; A Critical Review of<br />
Epidemiologic Evidence for Work-Related Musculoskeletal Disorders of the Neck, Upper<br />
Extremity, and Low Back”.Centers for Disease Control and Prevention, National Institute for<br />
Occupational Safety and Health (NIOSH).<br />
Bureau of Labor Statistics (2007).“Injuries, Illnesses, and Fatalities (IIF) program”.www.bls.gov.<br />
Colombini, D. (1998) 'An observational method for classifying exposure to repetitive movements<br />
of the upper limbs', Ergonomics, 41:9, 1261 – 1289.<br />
Grieco, A. (1998). “Application of the concise exposure index (OCRA) to tasks involving repetitive<br />
movements of the upper limbs in a variety of manufacturing industries: preliminary validations”,<br />
Ergonomics, 41:9, 1347 - 1356<br />
Instituto Mexicano del Seguro Social, (2006). “Información estadística en salud; accidentes de<br />
trabajo (1). www.imss.gob.mx<br />
Keyserling, W. M., Stetson, D. S., Silverstein, B. A. and Brouwer, M. L. (1993) “A checklist for<br />
evaluating ergonomic risk factors associated with upper extremity cumulative trauma disorders”,<br />
Ergonomics, 36:7, 807 – 831.<br />
Kumar, Shrawan (2001) 'Theories of musculoskeletal injury causation', Ergonomics, 44:1, 17 –<br />
47<br />
Li G., Buckle P. (1999).“ Current techniques for assessing physical exposure to work-related<br />
musculoskeletal risks, with emphasis on posture-based methods”. Ergonomics, 42; 5, 674 – 695.<br />
McAtamney, L. Corlet, N., (1973).“RULA; A survey method for the investigation of work-related<br />
upper limb disorders”. Applied Ergonomics; 24(2), 91-99.<br />
Muggleton, J. M., Allen, R. and Chappell, P. H.,(1999.) “Hand and arm injuries associated with<br />
repetitive manual work in industry: a review of disorders, risk factors and preventive measures”,<br />
Ergonomics, 42:5, 714 – 739.<br />
Rohmert Walter (1973). “Problems in determining rest allowances”. Applied Ergonomics, 4.2 91-<br />
95.<br />
Sociedad de Ergonomistas de México, A.C. 42
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Viikari-Juntura, Eira R. A. (1997) 'The scientific basis for making guidelines and standards to<br />
prevent work-related musculoskeletal disorders', Ergonomics, 40:10, 1097 – 1117<br />
DATA<br />
Height Weight<br />
Shoulder<br />
Angle<br />
Perceived<br />
Fatigue<br />
T exer T rec<br />
1.62 64 60 3 15 9.84<br />
1.61 59 45 2 14 5.23<br />
1.53 61 45 0 12 3.39<br />
1.56 60 40 1 18 7.72<br />
1.61 55 40 2 17 6.53<br />
1.61 65 45 3 10 2.73<br />
1.58 61 40 3 15 5.3<br />
1.54 58 35 2 20 7.19<br />
1.60 66 55 3 15 9.51<br />
1.65 58 35 3 19 8.35<br />
1.64 67 65 2 13 8.39<br />
1.56 57 55 3 16 8.01<br />
1.58 56 60 3 21 17.25<br />
1.62 65 40 2 18 9.99<br />
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1.61 67 46 2 15 1.33<br />
1.72 86 40 2 16 2.54<br />
1.62 74 40 2 14 0.91<br />
1.58 81 55 3 19 12.41<br />
1.58 54 30 3 21 6.82<br />
1.63 56 50 2 25 24.98<br />
1.62 64 60 3 21 22.05<br />
1.61 59 45 2 26 23.11<br />
1.53 61 45 0 24 17.88<br />
1.56 60 40 1 29 24.27<br />
1.61 55 40 2 27 19.82<br />
1.56 52 30 2 26 9.62<br />
1.61 65 45 3 24 35.11<br />
1.58 61 40 3 26 19.83<br />
1.54 58 35 2 29 17.54<br />
1.60 66 55 3 23 26.52<br />
1.60 53 35 2 22 9.04<br />
1.55 50 40 2 23 9.95<br />
1.65 58 35 3 27 19.4<br />
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1.64 67 65 2 21 26.51<br />
1.56 57 55 3 29 33.39<br />
1.58 56 60 3 25 26.22<br />
1.62 65 40 2 28 28.84<br />
1.68 102 45 3 22 14.33<br />
1.67 77 30 3 24 2.05<br />
1.72 86 40 2 28 9.75<br />
1.52 75 39 3 22 0.86<br />
1.62 74 40 2 21 2.42<br />
1.58 81 55 3 30 37.15<br />
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VERIFICATION OF MAXIMUM ACCEPTABLE WEIGHT OF LIFT, TABULATED IN<br />
LIBERTY MUTUAL TABLES, IN WOMEN OF CABORCA<br />
Jesús Rodolfo Guzmán Hernández 1 , Joaquín Vásquez Quiroga 1 ,<br />
Enrique Javier De La Vega Bustillos 2<br />
1 Grupo disciplinar de Ergonomía, Programa de Ingeniería Industrial,<br />
Universidad de Sonora Unidad Regional Norte, campus Caborca.<br />
Caborca, Sonora, México,<br />
rguzman@caborca.uson.mx, jovaqui@caborca.uson.mx<br />
2Maestría en Sistemas Industriales<br />
Instituto Tecnológico de Hermosillo<br />
Hermosillo, Sonora, México<br />
en_vega@ith.mx<br />
RESUMEN: Esta investigación se realizo con la intención de verificar la aplicación de los datos,<br />
de peso máximo de levantamiento (MLW), tabulados en las Tablas Liberty mutual, en la<br />
población laboral femenina de Caborca, Sonora, México. El experimento se limito a tareas de<br />
levantamiento vertical, frecuencia de uno por minuto, cajas de 34 cm de ancho (distancia desde el<br />
cuerpo), distancia de movimiento 51 cm, en tres niveles de levantamiento, bajo, que corresponde<br />
a levantamientos entre el suelo y la altura de nudillos, medio, de altura de nudillos a altura de<br />
hombros y alto, de altura de hombros a brazo extendido. Ésta fue realizada con alumnas<br />
estudiantes del programa de Ingeniería Industrial y de Sistemas adoptando el supuesto de que<br />
ellas pudieran estar formando parte de la fuerza laboral de las empresas establecidas en la<br />
región. Como resultado de este experimento se observo que los peso máximos tabulados en la<br />
Tabla Liberty Mutual para tareas similares a las de este experimento, son cuantitativamente<br />
mayores y existe evidencia estadística suficiente para rechazar que se pueden aplicar a la<br />
población laboral bajo estudio.<br />
Palabra clave: levantamiento de carga mujeres, tareas de levantamiento mujeres, máxima<br />
peso aceptable<br />
ABSTACT: The intention of this investigation was verify the application of maximum lifting weight<br />
data tabulated in the Liberty Mutual Tables (MLW), on the female labor population of Caborca,<br />
Sonora, Mexico. The experiment was limited to vertical lifting tasks, frequency of one per minute,<br />
boxes of 34 cm of wide (distance since the body), distance of movement 51 cm, in three levels of<br />
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lifting, low, that corresponds to lifting among the floor and the height of knuckles, medium, of<br />
height of knuckles to height of shoulders and high, of height of shoulders to arm extended. This<br />
investigation was done with 14 students, female gender, of the program Industrial and Systems<br />
Engineering, with the assumption that they could be part of the workforce of firms established in<br />
the region. As a result of this experiment was observed that the information of maximum<br />
acceptable weight tabulated in liberty mutual tables for similar tasks this experiment are<br />
quantitatively greater and there is sufficient statistical evidence to reject that we can apply it to<br />
working population under study.<br />
Keyword: women lifting weight, women lifting tasks, maximum acceptable weight<br />
1. INTRODUCTION<br />
Webster et al (1994) suggest that low back pain, associated with manual handling of loads,<br />
has been recognized as a major problem worldwide is the most costly injury in the industrial world.<br />
De la Vega (2006), citing The National Institute for Occupational Safety and Health (NIOSH) 1991,<br />
indicates the factors that directly influence the risk of lower back injuries are the weight and<br />
dimensions of the object, the distance is raised, lowered, pulled or pushed, and the repetition rate,<br />
as well as indirect factors such as age and physical condition of the worker. The consequences of<br />
ignoring the weight limit on the repetitive handling of loads can result in decreased performance at<br />
work and presents a risk of back pain that can become a cumulative trauma disorder (CTD) Putz-<br />
Anderson (1994). There are some studies about amount of weight that an individual is capable of<br />
lifting and about task design of the handling manual of loads with minimal risk of injury considering<br />
their characteristics and physical abilities. The reports of these studies represent guides to the<br />
industry which requires manually moving loads repeatedly. Among the most widely used guides<br />
include the NIOSH equation and the Liberty Mutual tables. The first is a tool through which,<br />
considering 7 factors involved in a lifting task, calculate the recommended weight limit (LPR) and,<br />
once known, is calculated the Lifting index that he is the ratio between the load weight and the<br />
recommended weight limit. The values that can take this index may fall into three risk zones,<br />
namely: limited risk (lifting index
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
3), this type of task is unacceptable from an ergonomic standpoint and should be changed.<br />
Moreover, the Liberty Mutual Company has developed the Liberty Mutual tables or tables of<br />
Snook which are a collection of tables which sets the maximum acceptable weight for help to<br />
control the risk of injury in the lower back in activities of manual handling of loads. In particular for<br />
lifting load, use the frequency of the task, the distance of movement of the load, the height at<br />
which the movement is placed, the size of the object and its grips and the horizontal distance<br />
(distance from the body) like parameters. With these parameters, the maximum acceptable weight<br />
it is tabulated in 10, 25, 50, 75 and 90 percentiles for male and female peoples. These studies<br />
and the respective conclusions were generated from the experimental data obtained of developed<br />
workers populations countries and the findings and their recommendations they are apply in<br />
Mexico without considering that data were obtained without including the characteristics and<br />
physical abilities of the Mexican population.<br />
In the Mexican Republic from 1992 to 2002 the Mexican Social Security Institute reported<br />
cases of 191.639 spine injuries, including back pain, accounting for 4.7% of total workplace<br />
injuries. Likewise, there is 42.422 dorsopatias with total disability in the period reported, including<br />
low back pain associated with lifting loads, representing 18.98% of total disability (Review IMSS<br />
2004), which indicates the relevance of the lesions of the spine. From the above, born the need to<br />
conduct this study which seeks to identify injury risks in applying the criteria of acceptable loads in<br />
the female population in Caborca, Sonora, Mexico, on grounds that it may be a cause for lower<br />
back pain that result of the manual materials handling, a problem that is occurring more often in<br />
companies. This raises the question "The maximum acceptable weight, reported by the Liberty<br />
Mutual tables for women, applies to women workers of Caborca? About this question the present<br />
investigation was made and it focuses only on tasks of vertical lift in frequency of one per minute,<br />
boxes width 34 cm, (distance from the body), movements 51 cm distance and three levels lifting:<br />
low , corresponding to uprisings between the ground and knuckle height, medium level, from<br />
height to knuckle to shoulder height and from shoulder height to arm's length.<br />
2. OBJETIVE<br />
The objective of this study is to identify risks in applying the criteria of maximum acceptable<br />
charges Liberty Mutual tabulated in Tables in the female working population Caborca, Sonora,<br />
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Mexico, because it can be one of the causes of lower back pain , resulting from manual material<br />
handling, is a problem that is occurring more often in business. This led to pose the question "The<br />
maximum acceptable weight women, the tables set by Liberty Mutual, is applicable to workers in<br />
Caborca?<br />
3. MATERIALS AND METHODS<br />
Details of the experiment, from where the Liberty Mutual Tables were made, it is found in the<br />
publications of Ciriello et al 1983, 1990 and 1991. The experiment was conducted using<br />
psychophysical approach. This approach requires that the subject is motivated by an incentive,<br />
and He,based on the perceived sensations, select the maximum load that it considers may sustain<br />
for a working day of 8 hr. According to Shoaf (1997), the major hypothesis of the psychophysical<br />
approach is that: at a given time, adjusted to 40 minutes, a person is able to predict the maximum<br />
weight or force that could be manipulated during a period of 8 hr; Mital (1983) states, people can<br />
estimate the amount of weight that can lift comfortably in 8 hr, based on experiencing fatigue in 25<br />
min and, hopefully, the weight selected by the subject is the same whether the person continues<br />
lifting it for 8 hr; Additionally, he states: there is no literature evidence to validate this claim.<br />
Under these criteria, basically, the subject is given control of the weight of the load, the participant<br />
monitors their own sensations of fatigue and adjusts the weight which he believes could bear. All<br />
other variables such as task frequency, load weight, distance of movement, etc.. are controlled by<br />
the experimenter. The participants in this experiment were 14 young female between 19 and 22<br />
years, they were university-level students they could be part of the workforce in the Caborca<br />
region. All signed in writing that they were free of lower back injury and had no cardiovascular<br />
disease. They used casual clothing and tennis shoes, jeans and loose shirts.<br />
To all participant in the experiment and for verify that the heights and distances of<br />
movement of loads in lifting tasks was be according to the experiment of Snook, were taken the<br />
anthropometric measures of weight, height, knuckle height, acromial height and extended arm<br />
height. Given the limited experience of the participants in manual handling of loads were given a<br />
belt to help keep your lower back straight. The participants were given training equal to the<br />
training done it in Ciriello et al (1983) experiment, to familiarize them with the activities to<br />
performed and gain experience in adjusting the load, increase or decrease according to their own<br />
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perceptions, they doing efforts themselves but without reaching a state of extreme tiredness,<br />
weakness, overheating or running out of breath, this, doing movements of vertically lifting , at a<br />
distance of 51 cm, with bending the knees and keeping your back straight, no turns or twists,<br />
without pull or push the load. For four consecutive days of tasks were performed lifting low (floor<br />
knuckle hight), increasing gradually the time. During first and second day were made a task for 10<br />
min with light load and heavy load respectively, the third day two tasks of 10 minutes each with<br />
light and heavy load respectively, without resting, the fourth day two tasks of 15 minutes with light<br />
load and heavy load respectively, without resting. The fifth, sixth and seventh days were for do the<br />
data collection. The daily tasks were made with duration of 40 minutes divided into two periods of<br />
20 minutes each one, without rest between periods, in the first period it gave them a heavy load<br />
and in the second light load, all randomly selected.<br />
Each day were made only the task for each level indicated for in the lifting Liberty Mutual<br />
tables, namely between floor level and knuckle height ( lifting low), between knuckle height and<br />
acromial height (lifting medium) and between airmail height and arm extended length (lifting<br />
height). For the experiment were used rigid polypropylene boxes with length of 55 cm (distance<br />
between hands), 34 cm wide (distance from the body) and 17 cm in height. The handgrips were<br />
located at half of the distance from the body and 15 cm from the floor of the box. The box<br />
contained a false bottom in which was placed a burden whose weight was randomly selected as in<br />
the experiment of Ciriello and Snook (1990). This hidden weight was not known by the participant<br />
in an attempt to minimize the visual effect. The load management was welding rods and it was<br />
used a balance T31P Ohaus, a decimal minute chronometer, a bell and shelves height-adjustable.<br />
For each level of uprising were select, at random, 14 heavy load values, between 32 and 45 kg,<br />
then was decreased in 3 kg each, which corresponds to the box weight, and the lid of the double<br />
bottom, the resulting value were divides random, to place the burden in the hidden compartment<br />
and the visible, subsequently the same procedure was performed for 14 light loads between 2 and<br />
18 kg, Snook (1990). These two procedures were repeated for each of the three levels of lifting<br />
the experiment. In the collection of field data were given in the first period a heavy load and the<br />
second period a light load., Participants adjusted the load in each period, they decreased or<br />
increased it according to their own perceptions until it represented the maximum they could lift in 8<br />
hr of task, if the load of the second period was between 15% of the first, the average of the two<br />
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loads is registered as the maximum acceptable load of the participant, otherwise the information is<br />
removed and a new test was performed.<br />
4. RESULTS AND DISCUSSION<br />
According to the working hypothesis raised in this investigation, if the maximum acceptable weight<br />
(MAW) of Table Liberty Mutual is applicable to the female population of the Caborca region, then<br />
the percentile distribution of the maximum load obtained from the participants, must statistically to<br />
exist a matching with the distribution of the liberty mutual table percentiles. Under this approach<br />
was performed the analysis for low level lifting. The results of the analysis are show in Table No 1<br />
Table 1 Analysis of field data, low level<br />
From the above table it is seen that for the 10th percentile there is not sufficient evidence to<br />
liberty mutual tabla data Hypotesis test<br />
MAW Null<br />
standard<br />
percentile (Kg) hypothesis statistical test desviation t α decisión<br />
90 11 P0 = 0.90 p= 0.79 0.08 -1.38 0.10 No rechazar Ho<br />
75 14 P0 = 0.75 p= 0.36 0.12 -3.25 0.00 Rechazar Ho<br />
50 16 P0 = 0.50 p= 0.21 0.13 -2.23 0.02 Rechazar Ho<br />
25 19 P0 = 0.25 p= 0.00 0.12 -2.08 0.03 Rechazar Ho<br />
10 22 P0 = 0.10 p= 0.00 0.08 -1.25 0.12 No rechazar Ho<br />
reject the null hypothesis. For 75, 50 and 25 percentile the significance levels of the test statistic<br />
permit reject the null hypothesis. The 10th percentile, has significance level to accept Ho but, is<br />
not feasible to accept the hypothesis that it applies the maximum load in the female working<br />
population Caborca because there is no real data to the percentiles 25 and 10, for what there is<br />
certainty to make the decision that both hypotheses may be rejected.<br />
For mid level lifting was performed an analysis similar to the previous data, the obtained<br />
information shown in Table No 2<br />
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Table 2 Analysis of field data, medium level<br />
liberty mutual tabla<br />
data Hypotesis test<br />
MAW Null<br />
standard<br />
percentile (Kg) hypothesis statistical test desviation t α decisión<br />
90 10 P0 = 0.90 p= 0.64 0.08 -3.25 0.00 Rechazar Ho<br />
75 12 P0 = 0.75 p= 0.50 0.12 -2.08 0.03 Rechazar Ho<br />
50 14 P0 = 0.50 p= 0.07 0.13 -3.31 0.00 Rechazar Ho<br />
25 16 P0 = 0.25 p=0.00 0.12 -2.08 0.03 Rechazar Ho<br />
10 18 P0 = 0.10 p= 0.0 0.08 -1.25 0.12 No rechazar Ho<br />
In the analysis can be seen that, for the 90, 75, 50 and 25 percentiles, the levels of significance of<br />
the test statistic are able to reject the null hypothesis. The 10th percentile has a high significance<br />
level to not accept H0 but there is not feasible to accept it because, there is not real evidence.<br />
For high lifting, was performed the analysis data that it is show in table3.<br />
Table 3 Analysis of field data, hight level<br />
liberty mutual tabla Hypotesis test<br />
MAW Null<br />
standard<br />
percentile (Kg) hypothesis statistical test desviation t α decisión<br />
90 9 P0 = 0.90 p= 0.77 0.08 -1.63 0.06 No rechazar Ho<br />
75 11 P0 = 0.75 p= 0.31 0.12 -3.67 0.00 rechazar Ho<br />
50 12 P0 = 0.50 p= 0.08 0.14 -3.00 0.01 rechazar Ho<br />
25 14 P0 = 0.25 p= 0.00 0.12 -2.08 0.03 rechazar Ho<br />
10 15 P0 = 0.10 p= 0.00 0.08 -1.25 0.12 No rechazar Ho<br />
datos correspondientes a 13 participantes<br />
In this last analysis presents a situation similar to the results for lifting low, one can see that<br />
for the 90th percentile there is no sufficient evidence to reject that, at this level, we can apply the<br />
maximum weight indicated by the table, for the percentiles 75, 50 and 25 the level of significance<br />
of the test statistic is at able to reject the null hypothesis. For the 10th and 25th percentiles, same<br />
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that in previous analysis is not feasible to accept the hypothesis Ho because there is no real<br />
evidence.<br />
5. CONCLUSIONS<br />
With the results and analysis of the data above we can accept that, in general, there is not<br />
sufficient evidence to accept that the maximum weight recommended in Liberty Mutual Table for<br />
lifting in women, in vertical lifting for frequency of one per minute, boxes of 34 cm wide (distance<br />
from the body), movement distance of 51 cm, at the three levels of survey, can be applied to the<br />
female workforce of the Caborca region without running the risk of injury. Given this information<br />
we can conclude that, it is not appropriate to apply the recommendations in Table Liberty Mutual<br />
in the female working population in the Caborca region since it is possible that this population has<br />
a lower lifting capacity or possibly with a less dispersion in capacity lifting. As a result of this<br />
research we recommend that define the acceptable maximum weights in lifting burdens on women<br />
in different regions of our country since there are no recommendations in this regard and are a<br />
cause of interest public health<br />
6.REFERENCES<br />
Ciriello, VM and Snook, SH 1990., Ergonomy 1990, vol 33, no.3 ,187-200, "The effects of<br />
container size, frequency and extended horizontal reach on maximum acceptable weights of lifting<br />
for female industrial workers."<br />
Ciriello, VM and Snook, SH 1991, Ergonomy 1991, Vol 34, No 9,1194-1213, "The design of<br />
manual handing tasks: revised tables of maximum acceptable weights and forces".<br />
De La Vega Bustillos, Enrique 2005, "checklists, methods and mathematical models for ergonomic<br />
evaluation of work environments", Technological Institute of Hermosillo<br />
http://www.estrucplan.com.ar/articulos/verarticulo.asp?IDArticulo=982 visited in June 2009<br />
Mital, Anil (1983), Human Factors, 1983, 25 (5), 488-49, The Psychophysical approach in manual<br />
lifting, a verification study.<br />
National Institute for Occupational and healt (NIOSH), 1991, "Scientific support documentation for<br />
revised 1991 NIOSH lifting equation".<br />
Putz Anderson, V (1994) "Cumulative Trauma Disorders. A Manual for Musculoskeletal Diseases<br />
of the Upper Limbs. Taylor & Francis, London.<br />
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Snook, SH and Ciriello, VM 1983, Human Factors, 1983.25 (5), 473-483, "A study of size,<br />
distance, Height and Frequency Effects of manual handling tasks<br />
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Force analysis in hands on highly repetitive work in maquila operations<br />
Fco. Octavio López Millán 1 , Enrique Javier de la Vega Bustillos 2 , MaríaJesúsTéllez Moroyoqui 1 ,<br />
LodevarPavlovichOviedo 2 , Bertha Leticia Ortiz Navar 3<br />
1 Departamento de Ingeniería Industrial.<br />
Instituto Tecnológico de Hermosillo. Ave. Tecnológico S.N.<br />
Hermosillo, Sonora, Mx. 83170<br />
Author’s e-mail: lopezoctavio@yahoo.com.mx<br />
2 División de Estudios de Posgrado e Investigación.<br />
Instituto Tecnológico de Hermosillo. Ave. Tecnológico S.N.<br />
Hermosillo, Sonora, Mx. 83170<br />
3 Departamento de Ingeniería Industrial.<br />
Instituto Tecnológico de Nogales. Ave. Instituto Tecnológico #911.<br />
Nogales, Sonora, Mx. 84065<br />
Resumen: Esta investigación se enfoca a analizar la fuerza como una función de tiempo en datos<br />
obtenidos en condiciones reales, considerando trabajo altamente repetitivo, donde las manos y<br />
dedos están expuestos a trabajo repetitivo y bajos esfuerzos. Se utilizo el diseño genera de<br />
medidas repetidas para analizar el comportamiento de la fuerza para ambas manos y pulgares.<br />
La hora, el turno y el día de trabajo fueron considerados como factores. La fuerza fue medida de<br />
la sexta a la octava hora en un intervalo de una hora, mientras que la semana empezó el lunes;<br />
el monitoreo fue de una semana. Los datos fueron obtenidos de plantas maquiladoras de las<br />
ciudades de Hermosillo y Nogales Sonora.<br />
Palabras Calve: Fuerza en manos, fuerza en pulgares, trabajo repetitivo, efecto acumulado<br />
de la fuerza, maquila.<br />
Abstract: The focus of this research is analyze how force is going as a function of time in data<br />
obtained from real work conditions, considering highly repetitive work, where the hands and<br />
fingers are exposed to repetitive work and low efforts. The repetitive measurement general design<br />
was used to analyze force behavior for both hands and both thumbs. The hour on the shift and the<br />
day week are the factors. Force was measured from the sixth hour to the eight hour on one hour<br />
interval, while the week day starts on Monday; the monitor is for a week. Data were obtained on<br />
maquila plants in Hermosillo and Nogales Sonora.<br />
Keywords: Hands force, thumbs force, repetitive work, cumulative effect of force, maquila.<br />
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1. Introduction<br />
The work doing by the hands has been a very important factor on manufacturing industries,<br />
especially on development countries, but the human being and its physical characteristics at<br />
service of material transformation on industrial process it is not an endless power supply, while<br />
time passthrough the day, physical performance could be affected and modified.<br />
As a result of frequent exposure to work there is a risk of musculoskeletal injuries, Bernard et al<br />
(1997) refers that it´s “were recognized as having occupational etiologic factors as early as the<br />
beginning of the 18th century,however, it was not until the 1970s that occupational factors were<br />
examined using epidemiologic methods, and the work-relatedness of these conditions began<br />
appearing regularly in the international scientific literature. Since then the literature has increased<br />
dramatically; more than six thousand scientific articles addressing ergonomics in the workplace<br />
have been published. Yet, the relationship between MSDs and work-related factors remains the<br />
subject of considerable debate.”<br />
To understand the musculoskeletal disorders problem, is required to identify the risk factors<br />
associated to these kinds of injuries. There is a wide literature about it and its don´t surprise, the<br />
problem has been studied for years and many point of views and results of research converge on<br />
the causes or risk factors, Colombini (1998) recognize mainly four risk factors; repetitive<br />
movements (frequency), force applied to the task, awkward postures and lack of enough recovery<br />
time on each work cycle. Muggleton (1999) includes vibration as a risk factor for the hand-wrist.<br />
McAtamney y Corlet (1973) refers to the risk factors as external factors, including a consideration<br />
for static work load on muscles. Furthermore, highly repetitive work may directly damage tendons<br />
through repeated stretching and elongation, as well as increase the likelihood of fatigue and<br />
decrease the opportunity for tissues to recover Keyserlin et al (1993).<br />
This work is focused in finding the relationship between frequency and the force that people can<br />
exert as a function of time and some anthropometric characteristics, the approach is; on the latest<br />
hours of the shift work, force become to decrease significant, at least statistically and there is a<br />
relationship between force and anthropometrics.<br />
2. Method<br />
One objective was collect data in working conditions, so the “experiment” was planned as follows:<br />
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• Find a process with highly repetitive operations; it is more than 300 units per hour.<br />
• The job involves extensive use of the hands and the fingers.<br />
• The anthropometrics measurements are for the hands and some generals:<br />
o Length of the hand.<br />
o Width of the hand.<br />
o Height of the hand.<br />
o Width of the wrist<br />
o Height of the wrist<br />
o Height of the thumb<br />
o Width of the thumb<br />
o Height of the middle finger<br />
o Width of the middle finger<br />
• The force on handgrip and thumb grip is measure with a Jamar© hand dynamometer and<br />
finger dynamometer. Every day 3 measurements are made every half hour from the sixth<br />
hour for the handgrip and finger grip for each side of the hands.<br />
• All data is collected and analyzed on statistical software (SPSS©)<br />
• Multiple linear regression is the tool to analyze the relationship between force and<br />
anthropometrics.<br />
• The repetitive measurements general model is used to analyze the force within hours and<br />
within days.<br />
• The data are from maquilas on Hermosillo and Nogales, Sonora, Mex.<br />
3. Results<br />
Is relevant to mention, again, how important get data from working conditions is, there was about<br />
50 operators who they were asked for to participate with the measurements for anthropometrics<br />
and force exertions, we appreciate that very much as well the maquila support to achieve the<br />
purpose of the research. Once data were collected and organized on worksheets next step is<br />
proceed to statistical analysis.<br />
The first part is finding the relationship between anthropometrics and force for each side on the<br />
hands, before the linear regression analysis, principal components was run to discriminate and<br />
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group variables, the next tables show it:The first iteration includes all variables resulting on seven<br />
groups and .717 acceptable KMO value, results are:<br />
Table 1. Total variance explained<br />
.<br />
The first rotated component matrix shows how variables are grouped in the seven groups:<br />
Table 2 Rotated Component Matrix<br />
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After several iterations, the target is find two groups; this final rotated matrix is next:<br />
Table 3 Final Rotated Component Matrix<br />
As values are shown on the table 4.3 the groups are formed with the higher coefficients; a first<br />
group is for; gender, height, weight and hand force. The second group are formed with; hand<br />
length, hand width, thumb width, thumb length and wrist width.<br />
Once groups are formed the next is linear regression analysis, the purpose here is just to found<br />
some kind of statistical relationship between variables or personal and force, next table shows the<br />
better relationship:<br />
Table 4 Linear Regression Model<br />
Predictor variables were; height, weight, thumb width, wrist width and hand length. Response<br />
variable is hand force.<br />
Linear regression shows a relationship between variables and force, that in general conditions, so<br />
next step is the analysis of force as a function of time.<br />
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Force behavior was tested using repetitive measurements general model for each hand.<br />
Additionally some extra test was run in order to probe variances and differences between hours<br />
and days. Results are in next tables. The first test is for right hand and the hour of the shift, table 5<br />
shows descriptive and table 6 shows Mauchy´s sphericity test.<br />
.<br />
.<br />
Table 5.Descriptive statistics for right hand and hour<br />
Table 6.Mauchy´ssphericity test<br />
Significance on Mauchy´s test is 0.00 that means differences between variances are not equals,<br />
so is necessary run the Bonferronistest for multiple comparisons, this test shows in what hour are<br />
a difference in average exerted force on right hand, table 7 shows it.<br />
Same proceed is for the left hand and next tables shows results for descriptive statistics,<br />
significance on Mauchy´s test is 0.00 that means differences between variances are not equals,<br />
so is necessary again run the Bonferronis test for multiple comparisons, this test shows in what<br />
hour are a difference in average exerted force on left hand.<br />
All statistical tests are for a 95% confidence level.<br />
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.<br />
.<br />
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Table 7.Bonferroni´s pair comparisons for right hand<br />
Table 8.Descriptive for left hand<br />
Table 9.Mauchy´s test for left hand.<br />
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Table 10.Bonferroni´s pair comparison for left hand.<br />
Same proceed is for both hands but the analysis is now within week days. Next tables shows<br />
results for descriptive statistics, significance on Mauchy´s test is 0.00 that means differences<br />
between variances are not equals, so is necessary again run the Bonferronis test for multiple<br />
comparisons, this test shows in what day are a difference in average exerted force the hand.<br />
.<br />
Right hand force descriptive are:<br />
Table 11.Mauchy´s test for day and right hand<br />
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.<br />
Table 12.Descriptive statistics for right hand and day.<br />
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Table 13.Bonferroni´s comparison pair test<br />
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Table 14.Mauchy´s test for day and left hand<br />
Table 15. Descriptive statistics for left hand and day<br />
Table 15.Bonferroni´s comparison pair test for left hand and day.<br />
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4. Discussion<br />
In an implicit form the purpose of this research was to show how force depend on anthropometric<br />
characteristics and how force is related with fatigue with a clear decrease pattern on force<br />
behavior trough hours and days.<br />
The first part tested by principal components and linear regression is positive; a statistical<br />
relationship does exist between hand and finger anthropometrics and force, in detail table 3 shows<br />
that, all values on above .600 on second group are related with the explanation of variance.<br />
In the second part the expected was that the greater values for hand forces were on the early hour<br />
and Monday, but results are not in that direction, for right hand force within hours, table 7 shows a<br />
difference only between the first hour of the test and 2.5 hours later. For left hand there is not<br />
statistical evidence that shows how force decrease in function of time.<br />
For hand force behavior related to day week, due to more than 90% of people are right-handed,<br />
the expected force behavior is that on Monday are the greater averages while on Friday should be<br />
the smaller averages. Table 12 shows that there is not any significative difference on right hand<br />
force average. For left hand force average, respect to Monday is valid a decreasing force behavior<br />
but statistically is valid only to Friday, on Tuesday the difference on average is only respect to<br />
Friday. The other days remain the same.<br />
As a final conclusion on this research the findings is that force has not a decreasing behavior due<br />
to hours or days, it makes necessary to increase the number of measurements and run a test for<br />
the thumb force.<br />
This fact, no decreasing force behavior should be not assumed as a fatigue free operations, while<br />
data were collected people says how at the end of the day they are with symptoms of pain and<br />
numbness on fingers, wrist, shoulder, neck and low back. Highly repetitive operations may have<br />
not an effect on force but that does not means that is an easy job.<br />
In maquilas, there is a lot of situations that should be improved, beyond manufacturing and quality<br />
is the human being, it is not only manpower, they are people and deserve a good place to<br />
workon.<br />
References<br />
Bernard, B. (1997). “Musculoskeletal Disorders and Workplace Factors; A Critical Review of<br />
Epidemiologic Evidence for Work-Related Musculoskeletal Disorders of the Neck, Upper<br />
Extremity, and Low Back”.Centers for Disease Control and Prevention, National Institute for<br />
Occupational Safety and Health (NIOSH).<br />
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Colombini, D. (1998) 'An observational method for classifying exposure to repetitive movements<br />
of the upper limbs', Ergonomics, 41:9, 1261 – 1289.<br />
McAtamney, L. Corlet, N., (1973).“RULA; A survey method for the investigation of work-related<br />
upper limb disorders”. Applied Ergonomics; 24(2), 91-99.<br />
Muggleton, J. M., Allen, R. and Chappell, P. H.,(1999.) “Hand and arm injuries associated with<br />
repetitive manual work in industry: a review of disorders, risk factors and preventive measures”,<br />
Ergonomics, 42:5, 714 – 739.<br />
Keyserling, W. M., Stetson, D. S., Silverstein, B. A. and Brouwer, M. L. (1993) “A checklist for<br />
evaluating ergonomic risk factors associated with upper extremity cumulative trauma disorders”,<br />
Ergonomics, 36:7, 807 – 831.<br />
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ENVIRONMENTAL CONDITIONS VERIFICATION IN FACILITIES <strong>DE</strong>SIGNED<br />
FOR NEW <strong>DE</strong>VELOPED PRE-SCHOOL LEVEL BUILDINGS IN THE<br />
EDUCATIONAL SECTOR IN HERMOSILLO, SONORA DURING 2007-2008.<br />
Francis María Quintero Díaz 1 , Manuel Sandoval Delgado 1<br />
1 Departamento de Investigación y Posgrado<br />
Instituto Tecnológico de Hermosillo.<br />
Ave. Tecnológico y Periférico Poniente S/N Colonia Sahuaro.<br />
Hermosillo, Sonora 83170<br />
Corresponding author’s e-mail: francis_mquinterod@hotmail.com, msandoval@ith.mx<br />
RESUMEN: Alrededor de todo el mundo, en el seno de toda clase de comunidades, con<br />
independencia de condiciones económicas, u otras características físicas, existen escuelas en<br />
condiciones precarias que se constituyen en barreras, a veces infranqueables, para que tanto los<br />
estudiantes, como profesores y personal técnico y administrativo desarrollen sus actividades<br />
normales dentro de los planteles con éxito. Tales condiciones pueden ser los niveles de ruido,<br />
iluminación, temperatura y ventilación a los que están expuestos diariamente, es por eso que<br />
hace dos años en la ciudad de Hermosillo sonora se empezaron a construir escuelas de nivel<br />
preescolar diseñadas para que estas condiciones no afecten las actividades de las personas que<br />
laboran en ellas.<br />
El propósito de esta investigación es realizar un estudio comparativo entre la normatividad<br />
correspondiente que rige el diseño y construcción del salón de clases donde laboran los niños y<br />
el personal de las instalaciones de los edificios de nueva creación del nivel preescolar en el<br />
sector educativo, en cuanto a medio ambiente se refiere; tales como ruido, iluminación y<br />
temperatura, con los parámetros realmente encontrados en dichas instalaciones.<br />
ABSTRACT: Around the world, within all kind of communities, regardless of the economic<br />
condition or any other physical characteristic there are schools in such poor conditions that create,<br />
sometimes insurmountable, barriers for students, teachers, as well as technical and administrative<br />
staff to successfully develop their diary activities within school. Such conditions are related with:<br />
noise level, lighting, temperature and ventilation which users are daily exposed to. As a response<br />
to this situation, the pre-school level facilities that were designed so that the environmental<br />
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conditions could not affect the daily activities of their users, started to be constructed two years<br />
ago in Hermosillo Sonora.<br />
The aim of this research is compare the corresponding regulations ruling the design and<br />
construction of classroom where children work and the personnel of pre-school level new facilities<br />
in the educational sector in terms of environment such as: noise, light and temperature with<br />
parameters actually found in these facilities.<br />
1. INTRODUCTION<br />
From the very moment of our birth we find ourselves immerse in a physical environment essential<br />
for life; however, if that environment degrades, it might become an enemy of our health that would<br />
chase us until the end (González, 1990).<br />
According to the Instituto de Infraestructura Física Educativa (INIFED) (Institute of Educational<br />
Physical Infrastructure), the classroom is where children and young people can reach through<br />
knowledge a great number of better opportunities; therefore, it is necessary that all Mexican<br />
students have access to quality education and schools that inspire and motivate the learning<br />
(INIFED, 2008).<br />
2. OBJECTIVE<br />
Decide if the design of facilities for new developed pre-school level buildings in the educational<br />
sector meets criteria established by the official standards regarding the design of the working<br />
environment (noise, lighting, temperature and ventilation).<br />
3. METHODOLOGY<br />
The methodology carried out in this research is accordance with the Official Standards ruling the<br />
design of working environment, such as:<br />
3.1 Federal Regulation of Security, Hygiene, and Working Environment.<br />
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This regulation establishes the necessary measures to prevent accidents and illness of work,<br />
trying to get the work done under safe, health and appropriate environmental conditions for<br />
workers, in accordance with the Federal Labor Law and the International Trade held and ratified<br />
by the United Mexican States related to these matters (Federal Regulation of Security, Hygiene,<br />
and Working Environment), (1997)<br />
3.2 Mexican Official Standards.<br />
3.2.1 Mexican Official Standard NOM-011-STPS-2001, security and health conditions in<br />
workplaces where noise is produced.<br />
Data collected in Appendix B evaluation of the level of exposure to noise tells the following:<br />
To evaluate noise in a permanent workplace the previous rule recommends that measuring spot<br />
must be located in the place the worker usually takes (in this particular case, the child) otherwise,<br />
as close as possible to it without hinder his/her work. In the same way, when a person works<br />
seated, the microphone has to be placed at the workers head average level. Measurements were<br />
taken as recommended.<br />
Measurements were taken to the following conditions:<br />
Children singing.<br />
Children performing current activities (NOM-011-STPS-2001), (1994).<br />
3.2.2 Mexican Official Standard NOM-015-STPS-1994, regarding to the labor exposure of high or<br />
low thermal conditions in workplaces.<br />
This rule makes some recommendations to take measurements, among them:<br />
The position of the measuring spots depends on needs and characteristic of each area<br />
and/or workplace. In this case, measurements were taken in the classroom central spot.<br />
The height of the measurement equipment was set in accordance with the height of the<br />
children’s work area (table): 60 cm.<br />
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The evaluation must be made at least three times during the 8 hour working day. Since<br />
children work day lasts 3 hours, it was decided to take measurements every hour, starting<br />
from the time they get in until the time they get of (NOM-015-STPS-1994), (1994).<br />
3.2.3 The Mexican Official Standard NOM-025-STPS-1999, lighting conditions in workplaces.<br />
The following activities were carried out according to law recommendations mentioned before:<br />
Workplace reconnaissance.<br />
Since sunlight and electric light are used, both conditions’ measurements were taken. For<br />
the electric light, lamps were turned on 20 minutes before.<br />
Measurement spots were set in accordance with the working area by the following formula:<br />
Where:<br />
Working area index/rate.<br />
Working area dimensions (length and width) in meters.<br />
Lamps height regarding the working surface, in meters.<br />
In this case:<br />
The number above is placed in the following table:<br />
Index of<br />
area<br />
Table 1. Proportion between the working area index and the number of measurement areas<br />
Minimum number of areas Number of areas to be considered<br />
to be evaluated<br />
by the limitation<br />
4 6<br />
9 12<br />
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16 20<br />
25 30<br />
Therefore, 9 areas were evaluated. Once the measurements were obtained, the % of Reflection<br />
Factor was calculated (to compare information later on) by the following method:<br />
Measurement spots must be the same as those set in the previous item.<br />
Calculation of the surface’s reflection factor:<br />
1. A first measurement (E1) is taken, with the luxmeter’s photocell facing the surface, at 10<br />
cm ± 2 cm distance, until the reading remains constant;<br />
2. In order to measure the incident light, the second measurement (E2) is taken with the<br />
photocell on the surface facing the opposite direction;<br />
3. The surface Reflection Factor (Kf ) is calculated with the following equation:<br />
(NOM-025-STPS-1999), (1999).<br />
3.3 Instituto Nacional de la Infraestructura Física Educativa (INIFED). (Institute of Educational<br />
Physical Infrastructure) The INIFED (2009) is the organization of the Federal Public Administration<br />
responsible for the construction, restoration, maintenance and equipment of the national<br />
educational physical infrastructure. It is important to mention that this institution does not say how<br />
to take measurements, it only provides parameters that must be met regarding the working<br />
environment; in addition to that it is based on the Mexican Official Standards.<br />
4. RESULTS<br />
Results shown below were collected in three classrooms during summer time.<br />
4.1 Noise:<br />
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(2<br />
)
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Table 2. Results of the Noise Factor’s (Lux) measurements.<br />
1 2 3<br />
Max Min Max Min Max Min<br />
Children singing 89 47.5 85 51.3 86.4 45.6<br />
Current activity 87.5 43.8 75.6 42.6 8 43.8<br />
4.2 Temperature.<br />
Table 3. Result of the Temperature Factor’s (Lux) measurements.<br />
1 2 3<br />
09:30 a.m.<br />
Min 24.5 22.8 24.7<br />
Average 25.9 24.8 26.6<br />
Max 27.3 26.7 28.4<br />
Min 28.9 28.4 29.8<br />
10:30 a.m. Average 29.5 29 29.7<br />
Max 30.2 29.7 29.7<br />
Min 33.3 32.4 34.2<br />
11:30 a.m. Average 33.7 33.2 34.7<br />
Max 34.1 34 35.2<br />
4.3 Lighting.<br />
Classroom<br />
Table 4. Results of the Lighting Factor’s measurements, classroom 1.<br />
LIGHTING (Lux) % REFLECTION FACTOR<br />
Natural Lighting Electric Lighting<br />
Natural<br />
Lighting<br />
Electric<br />
Lighting<br />
Max Min Max Min Max Min Max Min<br />
Measurement #1 264.7 233.3 640 590 40.0075 30.7758 28.5762 27.5937<br />
Measurement #2 534 486 748 716 26.7790 27.8600 29.2647 28.3798<br />
Measurement #3 547 478 947 756 27.7879 30.9205 29.2647 28.8359<br />
Measurement #4 912 892 1285 1234 24.4517 24.0022 25.0405 24.7081<br />
Measurement #5 1113 1070 1389 1373 29.3800 22.6168 26.3570 24.4136<br />
Measurement #6 1181 1139 1439 1434 22.5402 22.8709 23.3009 21.9456<br />
Measurement #7 494 398 918 891 30.6072 26.4070 27.1132 23.1986<br />
Measurement # 8 632 483 980 726 30.8723 26.2456 25.5478 21.6591<br />
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Table 5. Results of the Lighting Factor’s measurements, classroom 2.<br />
LIGHTING (Lux) % REFLECTION FACTOR<br />
Natural Lighting Electric Lighting<br />
Natural<br />
Lighting<br />
Electric<br />
Lighting<br />
Max Min Max Min Max Min Max Min<br />
Measurement #1 318 299 525 506 32.7044 33.7792 36.1904 36.5612<br />
Measurement #2 347 323 614 607 39.7694 41.7956 32.8990 32.1252<br />
Measurement #3 735 712 651 636 27.4829 26.1235 37.6344 27.9874<br />
Measurement #4 668 654 812 803 38.4730 36.5443 36.8226 33.7484<br />
Measurement #5 597 557 955 814 38.3584 39.1382 42.1989 39.9262<br />
Measurement #6 606 591 787 761 40.4290 32.4873 39.7712 40.3416<br />
Measurement #7 395 347 758 682 40.5063 44.6685 37.2031 39.8826<br />
Measurement # 8 465 446 872 832 38.9247 39.4618 37.2706 30.8894<br />
Classroom<br />
Table 6. Results of the Lighting Factor’s measurements, classroom 3.<br />
LIGHTING (Lux) % REFLECTION FACTOR<br />
Natural Lighting Electric Lighting<br />
Natural<br />
Lighting<br />
Electric<br />
Lighting<br />
Max Min Max Min Max Min Max Min<br />
Measurement #1 290 276 535 518 35.5172 36.5942 35.3271 35.9073<br />
Measurement #2 325 305 624 607 39.3846 43.9344 32.0512 32.1252<br />
Measurement #3 680 677 635 628 29.5588 28.0649 36.2204 27.0700<br />
Measurement #4 670 655 821 807 29.5522 28.5496 35.3227 31.7224<br />
Measurement #5 620 598 859 851 28.8709 26.7558 46.5657 38.0728<br />
Measurement #6 586 580 789 771 29.0102 28.2758 39.5437 39.6887<br />
Measurement #7 405 398 759 682 35.3086 35.4271 36.8906 39.8826<br />
Measurement # 8 486 476 921 897 26.3374 25.8403 35.1791 28.6510<br />
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Figure 1. Windows view.<br />
5. CONCLUSIONS.<br />
The Mexican Official Standard number 011 concerning to noise indicates that a hazardous<br />
situation occurs when dBs number surpasses 90. In this case the noise did not exceed the limit, at<br />
least not when children were there.<br />
The INIFED states that the advisable environmental conditions for working in a comfortable area,<br />
in the case of classrooms, are 18 to 25 Celsius, noticing that this condition is not fulfilled since<br />
most measurement exceeded 25 Celsius.<br />
According to the prevoiusly analized NOM 025, the lowest lighting level must be 300 (lux) for older<br />
people. As is noticed in the prevoius measurements, this parameter is not met, so that we can<br />
infer that light is not well distributed. The reflection on the furniture where kids work was another<br />
important issue that was evaluated and according to INIFED standards, the reflection highest<br />
value should be 50%, and as it is noticed in the previous measurements, does not exceed such<br />
level.<br />
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6. REFERENCES.<br />
González Gallego Santiago (1990). La ergonomía y el ordenador. Primera edición, Editorial<br />
Marcombo, S. A. Barcelona España.<br />
Instituto Nacional de la Infraestructura Física Educativa (INIFED), (2008).<br />
http://www.inifed.gob.mx/templates/objetivos.asp. Página visitada el 13 de agosto de 2009.<br />
INIFED, (2009). Volumen 3. Habitabilidad y funcionamiento. Tomo I. Diseño Arquitectónico.<br />
http://www.inifed.gob.mx/templates/normas%20t%C3%A9cnicas.asp. Página visitada el 12 de<br />
marzo de 2009.<br />
(NOM-011-STPS-2001), (1994). Publicada en el Diario Oficial de la Federación el 06 de julio de<br />
1994. México, D.F. http://www.stps.gob.mx/DGSST/normatividad/noms/Nom-011.pdf. Recopilada<br />
en la página el 6 de mayo de 2009.<br />
(NOM-015-STPS-1994), (1994). Publicada en el Diario Oficial de la Federación el 19 de julio de<br />
1993. México D.F. http://www.stps.gob.mx/DGSST/normatividad/noms/NOM-015.pdf. Recopilada<br />
en pagina el 6 de mayo de 2009.<br />
(NOM-025-STPS-1999), (1999). Publicada en el Diario Oficial de la Federación el 27 de<br />
septiembre de 2005, México, D.F.<br />
http://www.stps.gob.mx/DGSST/normatividad/noms/Nom-025.pdf. Recopilada en la página el 6 de<br />
mayo de 2009.<br />
(Reglamento Federal de seguridad, higiene y medio ambiente de trabajo), (1997). Publicado<br />
en el Diario Oficial de la Federación el 21 de enero de 1997. México, D.F.<br />
http://www.stps.gob.mx/marcojuridico/vinculos_juridico/reglamentos_marco/r_seguridad.pdf.<br />
Recopilada en la página el 6 de mayo de 2009.<br />
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ADVANTAGES OF THE ORTHOGONAL ARRANGEMENTS OF THE METHOD<br />
TAGUCHI IN THE <strong>DE</strong>SIGN OF EXPERIMENTS IN ERGONOMIC<br />
Alois Fabiani-Bello 1 , Humberto García-Castellanos 2 , and Rosa M. Reyes 2<br />
1 Programa de Doctorado en Ciencias de la Ingeniería (DOCI)<br />
Universidad Autónoma de Ciudad Juárez<br />
Ave. Del Charro 450N, C.P. 32190<br />
Cd. Juárez, Chihuahua, México.<br />
e-mail: fides.sde@gmail.com<br />
2 Departamento de Ingeniería Industrial<br />
Instituto Tecnológico de Ciudad Juárez<br />
Av. Tecnológico Nro. 1340<br />
Cd. Juárez, Chihuahua, México.<br />
Resumen: Los métodos estadísticos basados en la función Chi-Cuadrada son frecuentemente<br />
utilizados por los ergónomos y estas técnicas por su naturaleza no paramétrica usualmente<br />
requieren de una gran cantidad de datos experimentales con el correspondiente uso de recursos<br />
y contienen una importante dosis de subjetividad basada en la experiencia del experimentador.<br />
Las metodologías de experimentación podrían ser más rápidas y más económicas para tomar<br />
decisiones con la mejor información estadística posible utilizando técnicas apropiadas del Diseño<br />
de Experimentos. El autor Fabiani-Bello et.al. (Conergo, 2008) expone un método conceptual<br />
basado en simulación Monte Carlo y experimentos sin réplicas que fueron utilizados para planear<br />
la experimentación en ergonomía al categorizar la fatiga visual o astenopia. En base a la misma<br />
línea de trabajo Reyes-Martínez et.al. (Conergo, 2009) muestra los primeros resultados del<br />
método caracterizando la fatiga visual según publicaciones recientes dando a lugar la<br />
identificación clara de los factores que influyen en la astenopia y pone a prueba los métodos<br />
estadísticos tradicionales. Después de dos años de investigar las ventajas y limitaciones del<br />
método Taguchi en varias aplicaciones experimentales se propone en este artículo el método<br />
validado del diseño experimental basado en arreglos ortogonales del Método Taguchi que podría<br />
ser usado en los experimentos de la ergonomía donde, según el ajuste de niveles factoriales de<br />
diseño, es posible medir el impacto de estos arreglos en alguna variable de interés retomando las<br />
conclusiones obtenidas hasta la fecha sobre el tema.<br />
Palabras Clave: Metodo Taguchi, Arreglos Ortogonales, Diseño de Experimentos<br />
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2<br />
Abstract: The statistical methods based on the Chi-square of test ( χ ) are much used by the<br />
ergonomics and these need from a significant and big size of the sample with the corresponding<br />
use of resources and it contains an important dose of the subjectivity. Due to the cost of<br />
opportunity the methodologies must be more rapid in the treatment of the information, must be<br />
more economic and to take decisions with the best statistical information. Fabiani (2008) proposes<br />
a conceptual method based on simulation Monte Carlo that was used to plan the experimentation<br />
in ergonomics to the categorizer the visual fatigue. Based on the same line of work Reyes-<br />
Martínez et.al. (2009) it shows the first results of the method characterizing the visual fatigue as<br />
recent publications. The authoress identifies in a clear way the factors that influence the astenopia<br />
and it puts to test the statistical traditional methods. After two years of investigating the<br />
advantages and limitations of the method Taguchi in several experimental applications there is<br />
proposed in this article the validated method of the experimental design based on orthogonal<br />
arrangements of the Method Taguchi. The method that might be used in the experiments of the<br />
ergonomics where according to the level adjustment factorials of design it is possible to measure<br />
the impact of these arrangements in some variable of interest recapturing the conclusions<br />
obtained up to the date on the topic.<br />
.<br />
Key words: Taguchi Methods, Orthogonal Array, Experimental Design.<br />
1. INTRODUCTION<br />
The visual system is one of the principal organs of the human being since 80% of the emotions<br />
are perceived across the sight. The sciences that study the system of the sight begin to be<br />
interested in the labor matters at the end of the XIXth century turning into a more and more<br />
specializing professional activity and into a world more industrialized (Reyes-Martinez et.al, 2005).<br />
The new places and forms of work, the beginning of the automation and the systems of industrial<br />
production based on the competition for the quality (De la Vara, 2002) give place to a symptom<br />
that starts attracting attention of some specialists and especially of the companies because they<br />
realize that sometimes his workpeople can suffer a serious damage: The most common<br />
complaint, as for visual inconveniences, is vaguely described as " tired sight ". Other symptoms<br />
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indicate blurry sight or the difficulty to focus objects closely or of far, the unsteady vision and the<br />
double image. The headache is the most common general symptom, but not always it must be<br />
related to the visual weariness. Specifically, the symptoms of weariness or visual fatigue can be<br />
aggravated by diverse factors. On the other hand, the sight deteriorates gradually in the adults<br />
and this decrease is marked especially between 30 and 50 years (Reyes-Martinez et.al. 2005).<br />
The system of vision of the human being perceives the reality across the eyes, by means of these<br />
the brain perceives the signs and processes them; these signs are received in an environment<br />
with lighting, the color, the moisture between others they generate changeability in the system of<br />
vision. With the time, the visual system deteriorates for the rhythm of industrial repetitive work.<br />
The signs of Visual Fatigue as the frequency of blinking might be abstracted as exits of the effort<br />
of the system to face his fatigue (Okada, 2002).<br />
The relation between the Engineering of Quality and the Ergonomics is real because both want to<br />
improve the yield of a system, in the first case the experimentation has an important role in new<br />
products design, in developing manufacturing processes and in the improvement of processes<br />
and in the second case the characterization of factors so that the health is not damaged in the<br />
persons. With regard to the experimentation one of the most used methodologies and recognized<br />
for its efficiency is the one proposed by Dr. Genichi Taguchi. In Quality Engineering, it is<br />
mandatory to select the operative levels of the control factors that affect to critical characteristic of<br />
quality, and then abstracting the Visual Fatigue as a "characteristic of quality" it is necessary to<br />
minimize it.<br />
2. METHODOLOGY FOR SELECTING THE PARAMETERS<br />
To understand and to talk about the interaction between the persons and his environment implies<br />
respecting many methodological, statistical restrictions and even of anthropology; the experience<br />
says to us that these models that to the moment can be only theoretical, help to understand the<br />
behavior of the system more they do not allow to manipulate it. Our methodology is designed only<br />
for knowledge of relations cause - effect between the factors and the variable of exit of the<br />
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system. In this sense the method Taguchi for the prophecy of the output variable in the process is<br />
most adapted for our case; the process can be divided into five stages summarized in Table 1.<br />
N<br />
o.<br />
1 Preparation<br />
2.<br />
Table 1. Stages for the experimental design<br />
Stage Activity Content<br />
Determination of<br />
factors and levels<br />
1.1 Determine the experimental objective and targetcharacteristic<br />
values.<br />
1.2 Determine whether it is worthwhile to carry out the<br />
experiment under the current conditions.<br />
2.1 List all factors that relate to the objective (more<br />
than 50) with a Focus Group<br />
2.2 Select and determine factors and levels to be<br />
tested.<br />
3. Assignment 3.1 Assign factors and levels to the orthogonal array.<br />
4. Experiment<br />
5. Data analysis<br />
4.1 Eliminate the obstacles hindering the experiment.<br />
4.2 To continued the process of randomized<br />
experimentation generating only an experimental reply.<br />
4.3 With the simulation Monte Carlo all the possible<br />
outputs will be obtained<br />
5.1 To construct the correlogram and to interpret the<br />
coefficient of Pearson to characterize the incidental<br />
factors.<br />
5.3 Determine the optimum condition and to confirm<br />
them with the existing norms in the legal environment<br />
of Occupational Health.<br />
The sequence of the methodology and the recommendations of his application are based on the<br />
interpretation that the Dr. Teuro Mori does to the method Taguchi in his work titled originally "<br />
Taguchi Mesoddo or tsukatta yasashii shinjikken keikakuho nyumon " (1946).<br />
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2.1. Experimental Design Application: First and Second Stage – Preparation and<br />
Determination of factors y levels.<br />
The target of the experimentation applied to the ergonomics will have to maximize or minimize an<br />
effect and it is clear that to maximize a variable sometimes implies minimizing his complement.<br />
The clear identification of the variable of exit of the interaction between the man and the system is<br />
important. The scope of the experiment is to know the factors that they affect in the awaited result<br />
and to arrange them according to his contribution to the changeability of the system.<br />
At first more than 50 potential factors must be put in a list and to obtain this number it is necessary<br />
to ask medical specialists that have worked with the topic, it is key to confirm points of view of the<br />
participants and to assume a position based on the nature of the industry at which one is<br />
employed. The information will be better if it is investigated in the arbitrated publications,<br />
catalogues and tests previous.<br />
Another key of the ergonomic experimental process is to classify the factors and to define the<br />
levels of the experimentation, for this activity it is necessary to identify clearly the class of factor<br />
(Mori, 1946). As well as to classify to the factors in the function to his relation with the studied<br />
effect and to avoid the strong interaction between them, this is important for the complexity of the<br />
system in study. We cannot experiment with all the factors but the target here is to consider all the<br />
important factors. In this stage of the experimentation the people can have different opinions, in<br />
such a situation, we do not have to classify rigorously the factors and that's why we make use of<br />
orthogonal series to confirm his effect.<br />
After defining the factors, we determine his levels. The number of levels should be two, three, or<br />
four. The use of three levels is recommended in particular (G.Taguchi, 1986). The works of the<br />
theoretical investigation demonstrated that this type of level determination they generate<br />
quadratic’s terms in the model (Fabiani-Bello, 2008).<br />
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2.2. Experimental Design Application: Third Stage – Assignment.<br />
It is known that the most usual criterion to select the experimental design is the reduction of the<br />
variance of the regression coefficients. The key element to select a design that diminishes the<br />
variance is the orthogonality concept used by Taguchi in experimental designs. In fact, the<br />
complete factorial designs of two levels and the fractions of resolution III are orthogonal.<br />
In the ergonomic experimentation is possible to separate main effects and interactions using<br />
either of the following methods: (1) assign the main effect to the points to the linear graph<br />
assuming that interactions between three factors does not exist; (2) use a special orthogonal array<br />
where interactions confound equally with every level of the main effects. The first method uses the<br />
columns corresponding to the points on the linear graph en orthogonal arrays L 8 , L16,<br />
L32,<br />
L9<br />
and L 27 . For the second method L 12, L18<br />
and 36<br />
L orthogonal arrays are used which are of practical<br />
use in the industry for their effectiveness and reduction of costs (Wu, 1992).<br />
If we cannot anticipate possible interactions between factors, we can obtain quite a lot of<br />
information from past experience. But, if we cannot anticipate interactions, we can take any of the<br />
following approaches: (1) Assign the interaction between two factors. (2) Use orthogonal arrays<br />
12 , L18<br />
L or 36<br />
assign factors.<br />
L that does not generate interaction information. (3)Ignore interactions when you<br />
For experiments in ergonomics it is of interest principally to know the principal effects of factors,<br />
from what the second option is most recommended since it uses three levels and does not need<br />
to stop in the study of interactions that might be subjective in this stage of the process although<br />
the ability to anticipate is a part of technological know-how (G.Taguchi, 1986). For this reason the<br />
Taguchi methods for the case of study have been programmed in spreadsheets because these<br />
allow flexibility of programming for this type of algorithms. In fact, it contains statistical tools.<br />
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2.3. Experimental Design Application: Fourth Stage – Experimentation.<br />
In the industry the resources are in general limited it is very probable that the number of<br />
experiments is limited to the available budget, in this case a design factorial finished and with only<br />
one experimental response can be used, nevertheless the principal effects can contain an error<br />
generated by the external noise (Montgomery, 2006). The principal disability of this method<br />
consists of the fact that is known that to certain number of factors this process is expensive.<br />
The methodology Taguchi usually guarantees less experimental tests and makes use of the big<br />
advantage of the orthogonal arrangements then to construct a reliable model to know the value of<br />
the average of the process with the following equation:<br />
ˆ = y + ( A − y)<br />
+ ( B − y)<br />
+ ... + ( N − y)<br />
(1)<br />
y k<br />
r<br />
s<br />
Where:<br />
yˆ = theoretical average of the process.<br />
y = real average of the process.<br />
A , B,...<br />
N Are the experimental factors.<br />
k , r,...<br />
s Are the levels of the experimental factors.<br />
In this way, the Monte Carlo method is used to simulate all possible iterations in a predictive<br />
model of values of the average. This means that in our methodology there will be randomized the<br />
order of the capture of information to only one reply and later to obtain the theoretical model of the<br />
average based on the contribution of the principal effects, with the equation (1) there will be<br />
generated all the possible values of the average making use of the Simulation Monte Carlo. In<br />
studies realized with regard to the MAPE of the theoretical model his value is usually 4 %<br />
(Fabiani, 2008).<br />
With regard to the person chosen for the experiment, the International Organization of the Work<br />
tells that the "average" worker does not exist in the reality, but based on the requests of the<br />
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industrial work for which is experienced it is known that the profile of the person who executes the<br />
task and the Ergonomist jointly with the Engineer can suggest the conditions of an operator<br />
qualified for the position, this is that person who has necessary fitness, with required intelligence<br />
and instruction and who has acquired the workmanship and necessary knowledge to carry out the<br />
current work as norms of quality, quantity, health and safety (OIT, 1986).<br />
2.4 Application of experimental Design: Fifth Stage – Analysis of the information.<br />
Changing the levels of the factors, it is possible to know the interrelation between variables of<br />
entry and variables of exit to the system, the distributions of frequency for every variable and to<br />
the simulation of the experiment. Finally, the simulated population is validated comparing the<br />
levels of interrelation between variables and the percentage of obtained contribution of the<br />
ANOVA.<br />
The method allows to obtain a graphic report of different iterations to select the best combination<br />
of parameters. The relationship between the response variable and the independent variables is<br />
obtained based on the experience in previous investigations, which has found a narrow relation<br />
between coefficient of Pearson with the ANOVA (García-Castellanos and Fabiani-Bello, 2007).<br />
The following step is to verify the law with regard to the important factors in the response of the<br />
model and if norms do not exist on this matter it is necessary to choose the most appropriate<br />
levels of operation that maximize or minimize the response.<br />
3. CONCLUSIONS<br />
It has been demonstrated that Taguchi methods are an important tool. Due to its simplicity, the<br />
use of these methods has become frequent in different areas and different productive processes.<br />
After the statistical experimentation, the Taguchi methodology allows to predict the performance of<br />
a process by means. The implementation of this methodology is simple and practical and it does<br />
not require of advanced statistical knowledge. Also, the validation of the method presented here<br />
could be by means of a case of study.<br />
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4. REFERENCES<br />
Ross, Phillip J. (1996). Taguchi Techniques for Quality Engineering. McGraw-Hill Co., United<br />
States of America.<br />
Wu, Yuin, and Wu Alan (1997) Diseño Robusto utilizando los métodos Taguchi. Díaz de Santos<br />
S.A. Ed, Madrid, Spain.<br />
Suart P. Glen (1993), Taguchi Methods: a hands-on approach Addison-Wesley Co, Inc., United<br />
States of America.<br />
American Supplier Institute, Inc. (1987) Introduction to Quality Engineering: Course Manual.<br />
Center for Taguchi Methods, United States of America.<br />
Terou Mori (1946). The New Experimental Design, ASI Press, United States of America.<br />
Nelson Rodríguez (1999), Aplicación del Diseño de Experimentos para determinar el máximo<br />
peso aceptable en el manejo manual de materiales, Departamento de Ingeniería<br />
Industrial, Universidad de los Andes, Colombia.<br />
Tames Gonzalez S, Mart'nez-Alcántara S., Use of personal computers and health damages in<br />
newspaper industry workers. Salud Publica Mex 1993;35:177-185, Mexico.<br />
Rosa María Reyes Martínez M.C et al. (2005), Ergoftalmología: Análisis de los Factores que<br />
Inciden Astenopía de los Trabajadores de Inspección Visual Industria Electrónica de<br />
Ciudad Juárez, Memorias del VII Congreso Internacional de Ergonomía, Nuevo León,<br />
México, 3 al 5 de noviembre del 2005.<br />
Akira Okada (2001), Medición de la "Fatiga Visual", Universidad de Osaka, Panasonic Services<br />
(Central), Sancho de Ávila, 54, 1ª planta, Barcelona, Spain.<br />
Guillermo Martínez de la Teja, Diseño ergonómico para estaciones de trabajo con<br />
computadoras, Memorias del II Congreso Internacional de Ergonomía, Ciudad Juárez,<br />
México, Mayo 2000.<br />
Victor García-Castellanos, Alois C. Fabiani-Bello, and Humberto Hijar-Rivera (2007), A<br />
Computing Approach Based On The Taguchi Methods To Optimize The Selection Of<br />
Factors For The Nominal-The-Best Characteristics, Proceedings Of The 12th Annual,<br />
International Conference On Industrial Engineering, Theory, Applications and Practice,<br />
Cancun, Mexico, November 4-7, 2007.<br />
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Fabiani-Bello, Alois (2008), Aportación Metodológica al Diseño de Productos Robustos según la<br />
filosofía de Genichi Taguchi, División de Estudios de Posgrado e Investigación, Instituto<br />
Tecnológico de Ciudad Juárez, México.<br />
Reyes-Martinez, Rosa (2009), Categorization of factors causing asthenopia en research<br />
professors at the itcj by Reading wit vdt: a shared experience, SEMAC 2009, pp. 154-166<br />
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ACA<strong>DE</strong>MIC ASSAYS FOR ERGONOMICS.<br />
LDI Zoe Madai Cruz Purata 1 , LDI María del Sagrario Medina Rodríguez 2 , Arq. Julio Gerardo<br />
Lorenzo Palomera 3<br />
1 Coordinadora de la Carrera de Diseño de Interiores.<br />
2 3 Facultad de Arquitectura, Diseño y Urbanismo.<br />
Universidad Autónoma de Tamaulipas.<br />
Campus Tampico – Madero.<br />
zoemadai@hotmail.com<br />
RESUMEN. Se presentan dos ensayos realizados en la Facultad de Arquitectura, Diseño y<br />
Urbanismo (FADU). En el contexto interactivo de las carreras de Arquitectura y Diseño de<br />
Interiores, se desarrolló un estudio básico del ambiente acústico que incide en el aula, por otro<br />
lado se hace una aproximación de análisis antropométrico de nuevo mobiliario para los talleres de<br />
diseño.<br />
El estudio acústico tiene como finalidad que el alumno se sensibilice con la noción ergonómica y<br />
se familiarice con herramientas elementales, como el decibelímetro, para diagnosticar y controlar<br />
el ambiente sonoro, ahora a nivel escolar, pensando en su aplicación en entornos reales. Se<br />
sigue un método de medición simple, en una secuencia predeterminada de espacios. Se<br />
obtienen indicadores no del todo adecuados para un óptimo ambiente de aprendizaje.<br />
El diagnóstico de mobiliario se aplica en un juego de restiradores “gemelos”, con dimensiones<br />
establecidas por el fabricante. Se aplica una técnica de observación de postura relacionada con<br />
el alcance y la holgura, de usuarios en interacción con el mueble, de una muestra de la población<br />
estudiantil en la FADU. Los resultados llevan a la reflexión de cómo la aparente comodidad puede<br />
ser realmente una lastimosa costumbre, a ser cultivada en los años de carrera universitaria.<br />
Palabras clave: Interiorismo. Bienestar. Ergonomía. Acústica. Antropometría.<br />
ABSTRACT. We present two tests conducted at the Faculty of Architecture, Design and Urbanism<br />
(FADU). In the interactive context of careers in Architecture and Interior Design, it was developed<br />
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a basic study of acoustic environment impact in the classroom. Then it was applied an simple<br />
anthropometric analysis on new design workshops furniture.<br />
The acoustic study aim was to sensitize students about ergonomic notion and become familiar<br />
with basic tools such as decibelímetro, diagnose and control the sound environment, now at<br />
school, thinking about its application in real environments. It was followed a simple measurement<br />
method, in a predetermined sequence of spaces. Obtained indicators were not entirely<br />
appropriate for optimum learning environment.<br />
The diagnosis of furniture applies drawing board in a game of "twins", with dimensions specified<br />
by the manufacturer. It was applied an observational technique of scope and slack related<br />
posture. User - furniture interaction was observed of a sample of the student population. The<br />
results lead to the reflection of how the apparent comfort can be really a pitiful habit to be<br />
cultivated in the years of college.<br />
Keywords: Interiorism. Welfare. Ergonomics. Acoustics. Anthropometry.<br />
PROLOGUE.<br />
We present two academic assays conducted at the Faculty of Architecture, Design and Urbanism<br />
(FADU)<br />
In the interactive context of Architecture and Interior Design careers, it was developed a basic<br />
study of acoustic environment impact in the classroom, besides an approximation of<br />
anthropometric analysis of new furniture for the design workshops. Both exercises are strategies<br />
to reduce the gap between design activities and ergonomics, as well as linking quality as a daily<br />
practice.<br />
Ergonomics as inherent quality factor should be fully present in the field of design. In practice it is<br />
found that various educational trends, not necessarily provide consumers welfare in their models.<br />
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The environmental experience as part of the learning process is student-way reference in its<br />
professional life. Hence the need to reorient educational objectives in design.<br />
Exercise 1: Acoustic study of a learning environment.<br />
1.1. INTRODUCTION. Conceptual Framework.<br />
As part of the exercise was revised conceptual framework based on Mapfre Foundation<br />
Ergonomics Handbook<br />
Ergonomics deals with the study of any physical environment from three sources: the<br />
measurable factors of the environment that are susceptible to modification, the physiological<br />
effects produced by these factors and also how the employee feels that environment. The sound<br />
from the physical point of view is a mechanical vibration transmitted through the air, capable of<br />
being perceived by the auditory organ.<br />
1.1.1. Sound effects in people.<br />
The sound effects can occur in people from three aspects: perception, extra-auditory effects,<br />
auditory effects.<br />
Perception.<br />
The inner ear acts as a transducer, transforming the physical signal (mechanical) in<br />
physiological signal (nervous), which is transmitted through the auditory nerve to auditory cortex,<br />
which produces the integration and interpretation of those signals.<br />
Extra-auditory effects.<br />
The fact that noise can cause physiological reactions of "stress" seems widely accepted, but has<br />
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not yet established that these reactions can produce pathological effects. However, an analysis of<br />
more than one hundred relevant literature indicates that the most important are:<br />
Modification of the cardiovascular system: blood and heart rate.<br />
Influence on muscle tone.<br />
Digestive disorders.<br />
Visual function alterations.<br />
Alterations on metabolism.<br />
Auditory effects.<br />
The auditory effects are: injury to the ear and difficulty in language comprehension. For the scope<br />
of the study, was only considered the first. In an environment where understanding of the word<br />
difficult, is very likely that there are difficulties that will lead to discomfort for the worker and work<br />
impairment. The spoken word is a sonic element with high information content, so the process of<br />
perception is determined by various acoustic phenomena and the special interpretation of the<br />
message conveyed by the word.<br />
1.1.2. Acoustic comfort.<br />
The type of noise that bothers more in an office environment, is produced by the talks. Each<br />
type of activity will be treated differently. Can be generalized in terms of noise levels, noise in<br />
manual labor began to be troublesome from 80-90 dB, matching the levels from which they can<br />
and assume the risk of deafness.<br />
1.1.3. Effectiveness.<br />
Noise can alter a person's efficiency decreased performance and increased errors and<br />
accidents. Rates were determined for intellectual work discomfort, for example Beranek (1969)<br />
and Wisner, setting graphic curves correlated noise level in decibels and octaves center<br />
frequencies. The scope of this assay was limited to a simple sequence of measurement, but<br />
checking on the charts for better understanding by students. (Mapfre Ergonomics Manual)<br />
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1.2. OBJECTIVES.<br />
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Sensitize Interior Design students on the need to adapt the environmental conditions for human<br />
activity, in this case, learning. To learn the use of simple measuring sound tools, to diagnose and<br />
monitor a sound environment.<br />
1.3. METHOD.<br />
It was simplified to an academic exercise, the procedure established in the Mexican Official Norm<br />
for the security about noise sources. So, establishing six significant locations in the FADU<br />
campus, the sound pressure was measured. It was used a type 1 sound level meter, with a range<br />
of 50 to 120 dB, for capturing only the sound pressure.<br />
The group of 15 students made measurements in the selected areas thus obtained 90<br />
different indicators. For practical reasons the group was subdivided into two: seven people were<br />
devoted to three sites, and 8 to the other three areas. It was registered measurements taken in<br />
each area for a period of five minutes, for each student.<br />
1.4. RESULTS.<br />
The entire series averages were obtained, performing a table summarizing the average of the<br />
measurements (see Table 1). The teacher previously presented in the classroom as an<br />
introduction to the exercise and how to do it, including a concise explanation of the sound level<br />
meter use.<br />
Table 1. Sound Pressure measurementes.<br />
Site. Sound Pressure. dB<br />
Exterior environment (far away site) 40<br />
Class room 67<br />
Library. 64<br />
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We compare the results:<br />
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Laboratories (under construction) 71<br />
Patio. 66<br />
Cafeteria. 73<br />
a) With the recommended values in the corresponding official Mexican standard, which is 68 dB<br />
from 6:00 to 22:00 and 65 dB from 22:00 to 6:00.<br />
b) With the levels recommended by the ILO (OIT).<br />
c) It was showed the graph produced by Beranek. Although not conducted a detailed acoustic<br />
study to develop positions on the curves plotted, the models allow students to view individual<br />
cases.<br />
It is noted that approximately 55-90 dB levels for intellectual labor, it is extremely painful,<br />
depending on sound frequency.<br />
Table 2. Sound Pressure levels. OIT (ILO).<br />
Effect on humans Sound Level dB. Sound source.<br />
Extremely harmful.<br />
Harmful.<br />
140 Jet engine unit.<br />
130 Riveter.<br />
120<br />
110<br />
100 Truck.<br />
90<br />
Pain threshold.<br />
Propeller aircraft.<br />
Rock drill.<br />
Chainsaw.<br />
Metalworking shop.<br />
dangerous. 80 Busy street (car traffic)<br />
Prevents talk. 70 Passenger car.<br />
60 Normal conversation.<br />
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Irritant. 50 Talk quietly.<br />
1.5. CONCLUSIONS.<br />
40<br />
30 Whispers.<br />
Music played on radio at low<br />
volume.<br />
20 City quiet floor.<br />
10<br />
Whisper<br />
(vegetation).<br />
of leaves<br />
0 Hearing threshold.<br />
It was expressed by the group the distinction of sounds within the classroom and outside, the<br />
habit of perceiving external sounds as part of the learning environment, like a sound<br />
accompaniment. Especially noticed some discomfort because the dominant noise abroad, is to<br />
talk out loud.<br />
Regarding the Library, a combination of whispers, voices, noise from air conditioning<br />
equipment, produce anxiety and stress in the interior. Inside the cafeteria, conversation is difficult<br />
because of the noise.<br />
It was found that the materials used in buildings are not insulated or sound-absorbing. They<br />
are generally flat surfaces finished in painted cement, windows aluminum bearing. Also it was<br />
noted the classrooms air conditioners, as sources of noise.<br />
The exercise participants were sensitized on to consider ergonomics to achieve acoustic<br />
comfort in the spaces.<br />
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2. ANALYSIS OF NEW <strong>DE</strong>SIGN WORKSHOPS FUNITURE.<br />
2.1. INTRODUCTION.<br />
In Design learning, we consider the experience as a key factor. Since the products generated will<br />
be used by users, which we seeks to satisfy. Considering as example the model of Kolb (1984),<br />
the traditional tendency is to exercise the conceptualization phase mostly in institutions. Taking a<br />
side step, we invited a group of students to think about their academic work. Leaving aside the<br />
conceptualization only about ergonomics, was experienced and observed the use of furniture for<br />
design: a drawing desk prototype.<br />
2.2. OBJECTIVES.<br />
The student through observation, conceptualization and experimentation known anthropometric<br />
parameters.<br />
2.3. METHOD.<br />
Concepts were presented using anthropometry concepts and anthropometric tables, considering<br />
the scope and parameters of clearance,<br />
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It was conducted a simple anthropometric prototype drawing board "Twins." Continued as a<br />
methodology: analytical observation of the furniture in situ and photographs, analysis of simulated<br />
activity in furniture-user interaction, considering heights from 1.65 to 1.83 meters, in both sexes.<br />
The positions were static. It took anthropometric reference tables published by Prado-Ávila (2007).<br />
Observations were made of the furniture itself and users interacting with the furniture. There were<br />
registered users feelings about.<br />
It was made a physical survey of the furniture. It consists of two drawing tables linked by a metal<br />
structure made with angles of different caliber and length. Among these was placed additional<br />
shelf. The seat is circular, wood, supported on a rotating structure, a wheel support flange at the<br />
base, allows translation moves, subject to a pivot (see Figure 1). At first glance it seemed<br />
interesting.<br />
Figure 1. “Twins” Drawing Board Prototype<br />
They were invited to use the furniture first requesting suit as they liked it. Later they went in static<br />
postures leading to experience and visualize the scope and clearance parameters, comparing<br />
dimensions between the object and the person.<br />
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2.4. RESULTS.<br />
Discoveries:<br />
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The table surface measures 70 x 80 cm which is insufficient to work in a drawing paper sheet, in<br />
addition, there is no support for the drawing tools on the table and they could slip. Other coating is<br />
also recommended as this would prevent the tape off the ground especially because the climate<br />
humidity.<br />
It is needed an convenient adjustable board angle; it was fixed. Since the scope distances ratio<br />
from the user's fingertips on the furniture, creates an awkward bend in the lower back and also<br />
high tension in the shoulders and neck. Raise the height floor-edge of the table (0.91 mts.) would<br />
help to correct posture, facilitating work with the spine erect. For 95th percentile person said he<br />
felt comfortable until he was told to straighten the back (see Figure 2).<br />
Figure 2. Working posture: "comfortable" and erect. Percentile 95.<br />
It is suggested that in addition to the intermediate table support, useful for holding backpacks or<br />
bags, adding a drawer along the front edge of the table in each module for drawing and painting<br />
tools at hand. It is recommended to add a table with pen holders, whose support is articulated, at<br />
least one of the vertical bars of the support desk, and free rotation adaptable to the scope of the<br />
user. This little shelf complement the user's work when to laptop use is needed.<br />
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Regarding the seat, it was noted the absence of lumbar support (lower back), plus the hard, flat<br />
surface is uncomfortable after a while of use, is proposed to be padded, in a broader measure<br />
even for obese people, as default timber is still important to be configured curves of the buttocks<br />
and knee. It would be advisable to consider a footrest support tube in the bank, and the swivel<br />
seat is height adjustment screw. People in 5th percentile needed to rely on tip toes on the ground<br />
(see Figure 3).<br />
2.5. CONCLUSIONS.<br />
Figure 3. Sitting posture Percentile 5.<br />
Continuing the efforts to sensitize the academic population at the Faculty of Architecture, Design<br />
and Urbanism of the UAT, to update the application of ergonomics, we believe these tests<br />
successful. The training process needs to adapt to the dynamic professional. In the field of design,<br />
experience is gained from learning in workshops and classrooms.<br />
In the second exercise, underwent an apparent "comfort" in the use of furniture design from the<br />
anthropometric point of view, and recognized awkward postures. The experience generated<br />
improvement ideas.<br />
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5. REFERENCES.<br />
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Ávila Ch. R.- Prado L., L. – González M., L (2007). Dimensiones antropométricas. Población<br />
Latinoamericana. Universidad de Guadalajara. Centro Universitario de Arte, Arquitectura y<br />
Diseño. Centro de Investigaciones en Ergonomía. México.<br />
Beranek, Leo L. (1969). Acústica. Editorial Hispanoamericana. Buenos Aires.<br />
Fundación Mapfre (1997). Manual de Ergonomía. Editorial Mapfre. Madrd.<br />
NORMA Oficial Mexicana NOM-081-ECOL-1994. Límites máximos permisibles de emisión de<br />
ruido de las fuentes fijas y su método de medición.<br />
http://www.sma.df.gob.mx/tsai/archivos/pdf/12nom-081-ecol-1994.pdf<br />
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ANALYSIS OF CORRELATION BETWEEN THE VARIABLES OF<br />
TEMPERATURE, STRENGTH AND CYCLES PER MINUTE TO<br />
PERFORM HORIZONTAL REPETITIVE MOVEMENTS OF THE WRIST<br />
Camargo Wilson Claudia 1, 2 , Rivera Valerio Abril A. 1 ,<br />
Rubio Martinez Jesus R. 1 , de la Vega Bustillos Enrique J. 3 ,<br />
López Bonilla Oscar R. 2 , Olguín Tiznado Jesús E. 1, 2 ,<br />
1, 2<br />
Báez López Yolanda A.<br />
1 Department of Industrial Engineering - Engineering Faculty Ensenada.<br />
Autonomous University of Baja California.<br />
Km. 103 Highway Tijuana-Ensenada S/N<br />
Ensenada, Baja California. Zip code 22760<br />
ccamargo@uabc.edu.mx, abrilriva@hotmail.com, rodolforubio@yahoo.com<br />
2 Division of Posgrade and Research MyDCI- Engineering Faculty Ensenada.<br />
Autonomous University of Baja California.<br />
Km. 103 Highway Tijuana-Ensenada S/N<br />
Ensenada, Baja California. 22760<br />
olopez@uabc.edu.mx, jeol79@uabc.edu.mx, yolanda@uabc.edu.mx<br />
3 Division of Postgraduate Studies and Research<br />
Technological Institute of Hermosillo<br />
Technological Avenue S/N<br />
Hermosillo, Sonora. 83170<br />
e_delavega_mx@yahoo.com<br />
RESUMEN. La necesidad de proteger a los trabajadores contra las causas que provocan tanto<br />
enfermedades profesionales como accidentes de trabajo es una cuestión indudable. De ahí el<br />
interés de analizar el comportamiento que tienen las variables de temperatura en el área de la<br />
muñeca, la fuerza y los ciclos por minuto ello al llevar a cabo movimientos repetitivos horizontales<br />
de la muñeca, los cuales son comúnmente encontrados en los lugares de trabajo. Objetivos:<br />
Correlacionar las variables de temperatura, fuerza y cantidad de movimientos por minuto cuando<br />
se trabaja con el movimiento repetitivo horizontal en el área de la muñeca. Delimitación del<br />
problema: Se simuló la jornada laboral de ocho horas con dos operadores (hombre y mujer)<br />
ejerciendo los movimientos horizontales, en las instalaciones de la Facultad de Ingeniería<br />
Ensenada de la Universidad Autónoma de Baja California. Metodología: Se simuló la jornada<br />
laboral con dos operadores ejerciendo los movimientos horizontales, para ello se realizó el<br />
registro de la temperatura en el área de la muñeca derecha (termógrafo sensorial Sköll), la fuerza<br />
del individuo (dinamómetro de torsión de muñeca Baseline) y los ciclos por minuto, los tres<br />
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registros mencionados anteriormente se realizaban cada diez minutos. Resultados: Los<br />
resultados obtenidos fueron los siguientes: en el operador 1, se encontró correlación en los ciclos<br />
por minuto contra temperatura y contra fuerza; además el máximo en: la temperatura fue<br />
35.93°C, la fuerza 82 kg y los ciclos por minuto fue de 138 movimientos y el mínimo en: la<br />
temperatura fue 28.11°C, la fuerza 36 kg y los ciclos por minuto fue de 93 movimientos; en el<br />
operador 2 la correlación que se manifestó fue la de ciclos por minuto contra temperatura;<br />
además el máximo en: la temperatura fue 34.87°C, la fuerza 63 kg y los ciclos por minuto fue de<br />
140 movimientos; y el mínimo en: la temperatura fue 29.38°C, la fuerza 32 kg y los ciclos por<br />
minuto fue de 100 movimientos. Conclusiones: En base a este estudio se concluye que: existe<br />
correlación entre temperatura contra los ciclos por minuto y entre la fuerza contra ciclos por<br />
minuto; asimismo que no existe correlación entre temperatura y fuerza.<br />
Palabras clave: Temperatura, Fuerza, Ciclos por minuto.<br />
ABSTRACT. The need to protect workers against the causes of occupational diseases and accidents<br />
is a no doubt question. Hence the interest to analyze the behavior with variables in temperature in<br />
the area of the wrist, strength and cycles per minute, that to perform horizontal repetitive<br />
movements of the wrist, which are commonly found in workplaces. Objective: The objective was to<br />
correlate the variables of temperature, strength and number of movements per minute when working<br />
with horizontal repetitive movement of the right hand wrist area. Delimitation of the problem: It was<br />
simulated a working day of 8 hours with 2 operators (man and women) exerting horizontal<br />
movements, on the installations of the Faculty of Engineering Ensenada of the Autonomous<br />
University of Baja California. Methodology: It was simulated a working day with two operators<br />
exerting horizontal movements, and for this making the temperature recorder in the area of the<br />
right hand wrist (sensorial thermograph Sköll), the strength of the operator (dynamometer wrist-<br />
twisting Baseline) and cycles per minute, the three mentioned records were made every ten<br />
minutes. Results: The obtained results were: in the operator 1 ,there was a correlation in cycles<br />
per minute against temperature and against strength, besides the maximum in: temperature was<br />
35.93°C, strength was 82 kg and cycles per minute was 138 movements and the minimum in:<br />
temperature was 28.11°C, strength was 36 kg and cycles per minute was 93 movements; in the<br />
operator 2: there was a correlation in cycles per minute, besides the maximum in: temperature<br />
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was 34.87°C, strength was 63 kg and cycles per minute was 140 movements and the minimum in:<br />
temperature was 29.38°C, strength was 32 kg and cycles per minute was 100 movements.<br />
Conclusion: On based on this study the conclusion was: correlation exists between temperature<br />
against cycles per minute and strength against cycles per minute; and there is no correlation<br />
between temperature and strength.<br />
Keywords: Temperature, Strength, Cycles per minute.<br />
1. INTRODUCTION<br />
The need to protect workers against the causes of occupational diseases and accidents is a<br />
question no doubt. All sources of work should carry out activities aimed at the prevention of<br />
occupational hazards, with consequent advantages in production and productivity, achieving<br />
greater social welfare, which is reflected in the economy of the company. The ergonomic<br />
approach is to design products and work to adapt them to the people and not vice versa. The logic<br />
that uses the ergonomics is based on the principle that people are more important than the<br />
objects or production processes; and therefore, cases where it arises any conflict of interest<br />
between people and things, should prevail people (Tortosa et al., 1999).<br />
Ergonomic hazards have been an issue to consider, for injuries caused to workers in work areas.<br />
For industry it is always important the health of the workers, because by avoiding the DTA's in it<br />
reduces their costs for disabilities, absenteeism and more importantly for investors.<br />
Musculoskeletal injuries are disorders characterized by an abnormal condition of muscle, tendons,<br />
nerves, vessels, joints, bones or ligaments, which results in impairment of motor or sensory<br />
function caused by exposure to risk factors: repetition, strength, inappropriate postures, contact<br />
stress and vibration (Sinclair, 2001). For example, some of the injuries and illnesses common in<br />
the wrist area causing repetitive or poorly designed work are:<br />
• Tenosynovitis: is an inflammation of the synovial capsule, this is the sheath that covers<br />
tendons. Tenosynovitis can occur in any tendon with a synovial sheath. However, most often<br />
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occurs in the hand, wrist or foot. Most cases of tenosynovitis are caused by injury, infection,<br />
twisting, repetitive movement as: operate a computer, working on an assembly line, the cashier of<br />
a bank, sewing, playing musical instruments like violin or guitar<br />
(http://nlmnih.gov/medlineplus/ency/article/001242.htm)<br />
• Ganglia: it is a cyst in a joint or tendon sheath, usually in the back of the hand or wrist.<br />
(http://www.itcilo.it/actrav/osh_es/módulos/ergo/ergoa.htm)<br />
• Epicondylitis: is an inflammation of muscle attachments at the epicondyle of the elbow, the<br />
pain may appear in the muscles of the forearm and wrist. The causes that provoke are: Task force<br />
loading and repeatability, often in stressful jobs such as carpentry, plastering or bricklaying.<br />
(http://www.tiroriojano.com/lesiones/EPICONDILITIS.htm)<br />
• Crimping finger: is an inflammation of the tendons and / or tendon sheaths of the fingers.<br />
By use of air guns or staplers (International Labor Organization, 2004).<br />
• Carpal Tunnel Syndrome: presented by the type of horizontal repetitive movement and the<br />
disease that affects people. It is a Repetitive Strain Injury better documented, currently classified<br />
as compensable occupational disease in many countries. This syndrome affects the median nerve<br />
(one of the principal nerve in the wrist). Extreme cases can lead to permanent disability due to the<br />
absolute inability to flex the wrist to perform tasks as simple as operating a computer or holding an<br />
object in the hand. Affects workers who process meat or poultry, supermarket cashiers who use<br />
electronic scanners, the use of vibrating hand tools.<br />
In the United States with this syndrome each worker loses more than 30 working days, a figure<br />
higher than absenteeism from amputations and fractures. It has been estimated annual cost of<br />
these lesions in more than 100 million dollars (International Labor Organization, 2004).<br />
These injuries and illnesses caused by workplace tools and poorly designed or inappropriate<br />
usually develop slowly over months or years. However, a worker wills usually signs and symptoms<br />
for a long time to indicate that something is wrong. For example, the worker will be uncomfortable<br />
while doing their work or feel pain in muscles or joints once home after work. You can also have<br />
small muscle twitches for some time. It is important to investigate the problems of this kind,<br />
because what may begin with a mere inconvenience in some cases can end in injury or disease<br />
that severely incapacitated workers.<br />
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Employees often have no choice and are forced to adapt to poorly designed work conditions that<br />
can seriously injure the hands, wrists, joints, back or other body parts. In particular, injuries can<br />
occur due to:<br />
• The repeated use over time vibrating tools and equipment,<br />
• Tools and tasks that require turning the hand movements of the joints, for example the work<br />
performed by many mechanics;<br />
• The application of strength in a forced position;<br />
• The application of excessive pressure on parts of the hand, back, wrists or joints.<br />
All of them will generate absenteeism and each day of absenteeism for health reasons is a cost. A<br />
day lost disability implies a direct cost and indirect. (Beevis, 2003; Derango, 2002; Hendrick,<br />
2003).<br />
This study aims to correlate the variables of temperature, strength and cycles per minute all this<br />
by repetitive horizontal movements, applied to a man and a woman which are commonly found in<br />
workplaces.<br />
The benefit of this study is that it will have social impact, economic and scientific:<br />
• The social impact, achieving avoid injury to the worker and it will be productive in your work area<br />
and have better social welfare.<br />
• The economic impact, because if the DTA's are avoided in work areas will reduce annual costs<br />
by the company.<br />
• The scientific impact, because it is a sensorial thermography technique actually not used.<br />
1.1 Related Articles<br />
Gold et. al., (2004) in the article entitled "Infrared Thermography for Examination of skin<br />
temperature in the dorsal hand office workers", identified differences between skin temperatures<br />
between 3 groups of office workers through dynamic thermography, we have the experiment when<br />
writing computer keyboard for 9 minutes at a time. It highlights the temperature of testing room as<br />
an important factor.<br />
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Ming, et. al., (2005) in the article entitled "Sympathetic pathology evidence by hand thermal<br />
anomalies in carpal tunnel syndrome", the aim of this study was to classify the pathology<br />
compassionate in carpal tunnel syndrome and the use of infrared thermography. Exercise was<br />
conducted in which subjects were kept at room temperature between 22 and 25˚C for 15 minutes<br />
at room temperature are highlighted in the testing room as an important factor.<br />
Zontak, et. al., (1998) in the article entitled "Dynamic Thermography: Analysis of hand<br />
temperature During exercise", the aim of this study was to characterize the effect of exercise and<br />
responses in the skin temperatures due to controlled levels of exercise temperature conditions,<br />
making a ergonomics bicycle.<br />
Tchou, et. al., (1991) in the article entitled "Thermographic observations in unilateral carpal tunnel<br />
syndrome: Report of 61 cases", its purpose was to characterize the effect of exercise and<br />
responses in the skin temperatures, as an exercise the balance of hands for 15.<br />
Kyeong-Seop, et. al., (2006) in the article entitled "Infrared Thermography in Human Hand"<br />
estimated temperature conditions that could cause mental stress. Dipping both hands in a<br />
container of water at a temperature of 3˚C.<br />
Ferreira, et. al., (2007) in the article titled "Exercise-Associated Thermographic Changes in Young<br />
and Elderly Subjects", determined thermographic temperature changes associated in elderly and<br />
young people, doing knee bends with a weight of 1 kilogram added to the same for 3 minutes.<br />
This study presents the following objectives:<br />
2. OBJECTIVE<br />
• To correlate the variables of temperature, strength and number of movements per minute when<br />
working with horizontal repetitive movement of the right hand wrist area.<br />
• To show the application of sensorial thermography.<br />
• To develop preliminary test emulating a manufacturing industry repetitive operation.<br />
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3. METHODOLOGY<br />
This study was performed at the facilities of the Autonomous University of Baja California from 5<br />
to September 11, 2009. The study involved a man and a woman using the dominant hand (both<br />
being right-handed), which are healthy people with age 24 being the average age of the<br />
economically active population, students in undergraduate and in unskilled industrial manual<br />
material handling.<br />
To achieve the objective of this study, was simulated eight-hour workday to exercise horizontal<br />
repetitive movements as shown in Figure 1.<br />
Figure 1: Horizontal repetitive movement<br />
The record was made to register the temperature in the area of the wrist with a sensorial<br />
thermograph Sköll for each operator placed at the height of the wrist in the right hand figure 2, the<br />
strength of the individual with a dynamometer wrist-twisting Baseline (Figure 3) and cycles per<br />
minute.<br />
Figure 2: Sensorial Thermograph Sköll<br />
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Figure 3: Dynamometer wrist-twisting Baseline<br />
It is noteworthy that the three records mentioned above were made with a timer (Figure 4) every<br />
ten minutes.<br />
Figure 4: Timer<br />
4. RESULTS<br />
The table 1 and 2 are shown in the data from the experiment with horizontal repetitive movement<br />
of the operator 1 and the operator 2 within 7 days. In the second line of the both tables: 1 means<br />
cycles per minute, 2 means strength and 3 means temperature.<br />
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Table 1. Data concentrate of the operator 1 in the 7 days.<br />
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Table 2. Data Concentrate of the operator 2 in the 7 days.<br />
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4.1 Analysis of correlation.<br />
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In the figure 1 is shown the correlation between temperature and strength in the 7 days, where r is<br />
0.041. As r is 0.041 and 0.119 which is lower than the critical value we conclude that H0 is not<br />
rejected as there is insufficient evidence to conclude that there is a significant linear correlation.<br />
Figure 1: Correlation between Temperature (°C) and<br />
Strength (Kg) of the operator 1 in the 7 days.<br />
In the figure 2 is shown the correlation between cycles per minute and temperature in the 7<br />
days, where r is 0.292. As r is 0.292 and 0.119 which is greater than the critical value we conclude<br />
that there is a significant linear correlation, and H0 is rejected.<br />
Figure 2: Correlation between cycles per minute and<br />
temperature (°C) of the operator 1 in the 7 days.<br />
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In the figure 3 is shown the correlation between cycles per minute and Power in the 7 days, with r<br />
of 0.266. As r is 0.266 and 0.119 which is greater than the critical value we conclude that there is<br />
a significant linear correlation, and H0 is rejected.<br />
Figure 3: Correlation between cycles per minute and<br />
strength (Kg) of the operator 1 in the 7 days.<br />
The table 3 is shown the results obtained from the variables of the operator 1 in the 7 days.<br />
Table 3: Results of the Operator 1 variables in the 7 days.<br />
The table 4 is shown the maximum and minimum values of the variables of temperature, strength<br />
and cycles per minute generated by day to perform horizontal repetitive movement of the operator<br />
1.<br />
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Table 4: Results of the operation range of the operator 1 per day.<br />
In the figure 4 is shown the correlation between temperature and strength in the 7 days, being r -<br />
0.072. As r is -0.072 and 0.119 which is lower than the critical value we conclude that H0 is not<br />
rejected as there is insufficient evidence to conclude that there is a significant linear correlation.<br />
Figure 4: Correlation between Temperature (°C) and<br />
Strength (Kg) of the operator 2 in the 7days.<br />
In the figure 5 is shown the correlation between cycles per minute and temperature in the 7 days,<br />
with r -0.172. As r is -0.172 and its absolute value is 0.172 and 0.119 which is greater than the<br />
critical value we conclude that there is a significant linear correlation, and H0 is rejected.<br />
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Figure 5: Correlation between cycles per minute and<br />
temperature (°C) of the operator 2 in the 7 days.<br />
In the figure 6 is shown the correlation between cycles per minute and Strength in the 7 days,<br />
being r -0.002 As r -0.002. and 0.119 which is lower than the critical value we conclude that H0 is<br />
not rejected as there is insufficient evidence to conclude that there is a significant linear<br />
correlation.<br />
Figure 6: Correlation between cycles per minute and<br />
Strength (Kg) of the operator 2 in the 7 days.<br />
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The table 5 is shown the results obtained from the operator 2 variables in the 7 days.<br />
Table 5: Results of the operator 2 variables in the 7 days.<br />
The table 6 is shown the maximum and minimum values of the variables of temperature, strength and<br />
cycles per minute generated by day to perform horizontal repetitive movement in the operator 2.<br />
Table 6: Results of the operating range of the operator 2 per day.<br />
5. CONCLUSIONS<br />
In the present study fulfilled the objective of correlating the variables temperature, strength, and<br />
cycles per minute that are manifested in the wrist area of the dominant hand (in this case the<br />
operators was the right hand) with horizontal repetitive movements during working day within a<br />
week.<br />
On based on this study the results were as follows: the operator 1 ,there was a correlation in<br />
cycles per minute against temperature and against strength, besides the maximum in:<br />
temperature was 35.93°C, strength was 82 kg and cycles per minute was 138 movements and the<br />
minimum in: temperature was 28.11°C, strength was 36 kg and cycles per minute was 93<br />
movements; the operator 2: there was a correlation in cycles per minute, besides the maximum in:<br />
temperature was 34.87°C, strength was 63 kg and cycles per minute was 140 movements and the<br />
minimum in: temperature was 29.38°C, strength was 32 kg and cycles per minute was 100<br />
movements.<br />
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The conclusion was: correlation exists between temperature against cycles per minute and<br />
strength against cycles per minute; and there is no correlation between temperature and strength.<br />
6. REFERENCES<br />
Beevis, D., (2003). Ergonomics-Costs and Benefits Revisited. Applied Ergonomics 34: 491-496.<br />
Derango, K. and Franzini, L., (2002). Economic Evaluations of Workplace Health Interventions:<br />
Theory and Literature Review. In Handbook of Occupational Health Psychology, Ed<br />
Washington D.C. American Psychological Association.<br />
Ferreira, J., Mendonça, L.C., Nunez, L.A., Andrade, A.C., Rebelatto J.R., and Salvini, T. (2007).<br />
Exercise-Associated Thermographic Changes in Young and Elderly Subjects, Federal<br />
University of Saint Carlos. Physics’ Institute of Saint Carlos, Sao Paulo University, Brazil.<br />
Gold E. J., Cherniack M., Buchholz B., (2004). Infrared Thermography for examination of skin<br />
temperature in the dorsal hand office workers, Eur J. Apply Physiol 93: 245-251.<br />
Hendrick, H.W., (2003). Determining the Cost-Benefits of Ergonomics Projects and Factors that<br />
lead to their Success. Applied Ergonomics 34: 419-427.<br />
International Training Center of the International Labor Organization. ITCILO: Home page.<br />
http://www.itcilo.it/actrav/osh_es/módulos/ergo/ergoa.htm<br />
Kyeong-Seop, K., Shin, S.W., Yoon, T.H., Kim, E.J., Lee, J.W. and Kim, I.Y. (2006). Infrared<br />
Thermography in Human Hand”, School of Biomedical Engineering, Chungju, Korea.<br />
Ming, Z., Zaproudina, N., Siivola, J., Nousiainen, U., Pietikainen S., (2005). Sympathetic<br />
pathology evidenced by hand thermal anomalies in carpal tunnel syndrome, ISP<br />
Pathophysiology: 137-141.<br />
International Labor Organization (2004). Labor Productivity in Latin America, is the same as 20 years<br />
ago, Magazine of occupational panorama of the OIT.<br />
Sinclair, D.T. and Graves, R.J. (2001). Feasibility of Developing a Simple Prototype Decision Aid<br />
for the Initial Medical Assessment of Work Related Upper Limb Disorders. University of<br />
Aberdeen. Department of Environmental & Occupational Medicine. Hse Books.<br />
Shooting Sport Club La Rioja, Shooting Sport Club La Rioja Home page:<br />
http://www.tiroriojano.com/lesiones/EPICONDILITIS.htm<br />
Tchou, S.F., Costich, J.C. Burguess, R., Lexington, K.Y. and Wexler C. (1992). Thermographic<br />
observations in unilateral Carpal Tunnel Syndrome: Report of 61 cases, The Journal of the<br />
hand surgery 17A: 631-637.<br />
Tortosa, L. and Garcia, C., Page, A. and Ferreras, A. (1999). Ergonomics and disability. Institute<br />
of Biomechanics of Valencia (IBV), Valencia. ISBN 84-923974-8-9.<br />
U.S. National Library of Medicine and National Institutes of Health. Medical Encyclopedia: Home<br />
page. http://nlm.nih.gov/medlineplus/ency/article/001242.htm<br />
Zontak, A., Sideman, S, Verbitsky, O. and Beyar, R., (1998). Dynamic Thermography: Analysis of<br />
hand temperature, Annals of Biomedical Engineering, Vol. 26, 988-993.<br />
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Temperature analysis on wrist surface due repetitive movement tasks using<br />
Sensorial Thermography to find out a possible pathology for a CTD<br />
Ordorica Villalvazo Javier 1,2 , Camargo Wilson Claudia 1,2 , De la Vega Bustillos Enrique 3 ,<br />
Olguín Tiznado Jesús E. 1, 2 , López Bonilla Oscar R. 2 , Limón Romero Jorge 1, 2 .<br />
1 Department of Industrial Engineering - Engineering Faculty Ensenada.<br />
Autonomous University of Baja California.<br />
Km. 103 Highway Tijuana-Ensenada S/N<br />
Ensenada, Baja California. 22760<br />
villalvazo@uabc.edu.mx, ccamargo@uabc.edu.mx<br />
2 Division of Posgrade and Research MyDCI- Engineering Faculty Ensenada.<br />
Autonomous University of Baja California.<br />
Km. 103 Highway Tijuana-Ensenada S/N<br />
Ensenada, Baja California. 22760<br />
jeol79@uabc.edu.mx, olopez@uabc.edu.mx, j.limon@uabc.edu.mx<br />
3 Division of Postgraduate Studies and Research.<br />
Technological Institute of Hermosillo.<br />
Technological Avenue S/N<br />
Hermosillo, Sonora. 83170<br />
e_delavega_mx@yahoo.com<br />
Resumen: A través de la historia se puede observar como la temperatura ha sido un indicador<br />
importante para determinar cambios importantes en los ecosistemas del planeta, en la resistencia<br />
de materiales para el diseño de nuevos productos, y también en el campo de la medicina<br />
analizando por ejemplo, fiebres ocasionadas por infecciones provocadas por nuevas<br />
enfermedades. A través de este estudio de las variaciones de temperatura corporales provocadas<br />
en los nervios del área de la muñeca generando la reducción en la habilidad muscular para<br />
realizar el trabajo debido a movimientos repetitivos, lo cual nos puede llevar a entender la<br />
patología de un Desorden de Trauma Acumulado (DTA), tomando en cuenta la termografía<br />
sensorial, ya que no es invasiva para el ser humano, que facilita la recolección y manipulación de<br />
los datos. Objetivos: Analizar cambios en los patrones de temperatura generados en el área de la<br />
muñeca. Mostrar la factibilidad de la aplicación de la termografía sensorial. Recabar información<br />
acerca de las variables no laborales (edad, género, peso, entre otras) y laborales (repetitividad,<br />
temperatura del área de trabajo). Desarrollar las pruebas preliminares emulando la operación<br />
ejecutada en la industria y que involucra los movimientos repetitivos. Identificar los puntos de<br />
estrés máximo alcanzados durante un periodo de operación describiendo síntomas detectados.<br />
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Delimitación del problema: Este estudio se realizó con sólo un estudiante de la Facultad de<br />
Ingeniería Ensenada de la UABC. Metodología: Se seleccionó a un estudiante en condiciones<br />
físicas normales, quien realizó pruebas en un laboratorio aplicando el protocolo para el<br />
experimento haciendo uso de la termografía sensorial. Resultados: Las temperaturas máximas<br />
alcanzadas en ambas muñecas fueron en periodos de operación en tiempos muy similares. Se<br />
detectaron molestias en el hombro derecho en el rango donde se identifican las temperaturas<br />
más altas durante el proceso de la operación para ambas muñecas. A través del ajuste de una<br />
ecuación de tercer orden fue posible explicar el comportamiento de las temperaturas.<br />
Conclusiones: Por medio de la termografía sensorial es posible analizar patrones de temperatura,<br />
ligarlos a una estadística creando la posible patología de un DTA y que pudieran servir en futuras<br />
investigaciones.<br />
Palabras clave: Termografía sensorial, DTA, temperatura.<br />
Abstract: Through history we have observed how temperature has been an important factor to<br />
take in account in order to detect many several climatic changes in planet. This factor has been<br />
deeply studied in weather changes, material resistance for the designing of new products, and<br />
also, in the medicine field obtaining remarkable results studying fiber causes in multiple diseases,<br />
most of them related to infections. This research aimed at evaluating body temperature variations<br />
on wrist surface that can cause muscle disability and weakness due repetitive movement tasks.<br />
The work contributes to discover a possible Cumulative Trauma Disorder (CTD) pathology using<br />
sensorial Thermography as an innovative and dynamic tool, since this is not a non-invasive<br />
technique it means that can not cause any damage on humans. It is a powerful tool also, because<br />
allow investigators to manipulate data and import or export them to statistics programs.<br />
Objectives: Analyze temperature pattern changes and show up the feasibility of the sensorial<br />
thermography. Collect information about different kind of variables that may affect the study, like<br />
age, gender, weight, height, and others like repetitiveness and work area temperature. Perform<br />
preliminary test emulating an operation highly repetitive in the textile industry. Identify maximum<br />
stress points while preliminary test is taking place, and at the same moment detect key symptoms.<br />
Methodology: An Industrial engineering student in good shape was selected to perform the<br />
repetitive task in a lab by following the experiment protocol and using sensorial thermography.<br />
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Results: Maximum temperatures in both wrists were detected in similar periods of time. The<br />
student showed pain symptoms in right shoulder while doing the task. It was detected while the<br />
maximum temperature range was reached in both wrists. By adjusting a third order equation it<br />
was possible to explain the temperature behavior. Conclusions: Through sensorial thermography<br />
is possible to analyze temperature pattern and link them to statistics creating a possible CTD<br />
pathology that could help in future researches.<br />
Keywords: Sensorial thermography, CTD, temperature.<br />
1. INTRODUCTION<br />
The highly repetitive activities are a disease that in nowadays affect thousands of people<br />
developing several cumulative trauma disorders. In many times this kind of disorders are confused<br />
with other kind of diseases. The cumulative trauma disorders cause damages on body tissues due<br />
to excess motion periods. It can be developed through pass of the time. Furthermore, today, the<br />
DTA’S are well known as an industrial epidemic causing a periodic disability. The experimentation<br />
was based on temperature analysis generated on wrist area of one subject, which is the area<br />
where the carpal tunnel syndrome begins. A repetitive movement simulation consisted in an<br />
operation emulated from a local textile industry. The study was taken using sensorial<br />
thermography.<br />
The thermography is a non invasive technique without biologic hazard. It detects, measures, and<br />
converts invisible, surface body heat into visible display which is the photographed or videotaped<br />
as a permanent record. This type of thermography it is the one we call infrared thermography<br />
(Feldman al., 1991). The digital sensorial thermography it is different from the infrared one,<br />
because it is widely used to look for temperature patterns on skin surface through sensor contact<br />
(Zontak et al., 1998).<br />
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This technology was born while the submarine thermographs a long time ago were developed to<br />
measure underwater temperatures. It has many applications such as oceanography, marine<br />
ecology, industry, and many others (Lopez, 1992).<br />
This study arose from three important questions, what is the subject temperature behavior during<br />
the motion? What is the relationship between pain symptoms and temperature data? What are the<br />
max stress points? A close examination of the literature shoes that no study has been devoted to<br />
these problems emulating a motion executed in the textile industry in order to analyze cutaneous<br />
temperatures.<br />
However a swimming study was carried out with a professional swimmer in a pool where the<br />
swimmer practiced several swimming styles, so researchers could analyze the temperatures after<br />
each swimming style (Zaidi et al., 2007).<br />
The Study was carried out in a closed room where the temperature was a relevant parameter. We<br />
use a home heater to try to control the temperature, because according with the literature, the<br />
most useful temperature parameter in experimentations of this kind is between 20 and 25 degrees<br />
(E.Y.K, N.G. et al., 2005).<br />
It is advisable to specify that the present work is not a statistical study. The results obtained in this<br />
study cannot be considered to have a universal character since only one subject was taken into<br />
account for our experimentation. However we are doing many test with more subjects at the<br />
campus to make temperature behavior inferences. The objectives in this preliminary<br />
experimentation were to show the applications of the sensorial thermography on one hand, and on<br />
the other hand, to show the maximum temperature stress points.<br />
This Study presents the following objectives:<br />
2. OBJETIVES<br />
• To analyze temperature pattern changes generated on wrist area.<br />
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• To show the application of sensorial thermography.<br />
• To collect information about subject gender, age, mass and others.<br />
• To collect information about repetitive cycles and temperature working area.<br />
• To develop preliminary test emulating a textile industry repetitive operation.<br />
• To identify maximum stress points during the operation period and to describe symptoms<br />
detected.<br />
3.1 The subject<br />
3. METHODOLOGHY<br />
The subject taking in part in this study is a subject in good shape. The principal anthropometric<br />
characteristics of the subject are summarized in table 1.<br />
Table 1. Anthropometric data for the subject<br />
Age Height<br />
Mass<br />
(m)<br />
(Kg)<br />
Subject 29 1.63 60<br />
3.2 Equipment and data analysis<br />
All the cutaneous temperatures were taken using a sensorial thermograph Sköll with a<br />
temperature range of 0˚C – 40˚C, a precision of ±.3˚C, and a resolution of 1 degree, a<br />
microporous tape (Lopez, 1992), a laptop (COMPAQ Intel Pentium Dual Core), a home heater.<br />
Programming the thermographs was possible using a program called Akela. Also a statistical<br />
program was used for data analysis (Minitab 15) and Microsoft Excel 2007.<br />
3.3 Protocol<br />
Subjects were asked to refrain from intense exercise, caffeine, smoking, alcohol and smoking for<br />
20 minutes prior to the experiment (Gold et al., 2004) and (Gold et al., 2009) because smoking<br />
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could produce a massive reduction of body temperature and alcohol a raise of body temperature.<br />
Previous studies have demonstrated that the corporal temperature stabilization takes about 20<br />
minutes due to a reduction on body metabolism (E.Y.K NG y Sim en E.Y.NG et al., 2008).<br />
Having the opportunity to use a home heater we warmed up the room temperature for the<br />
experiment between 20-25 degrees (E.Y.K NG et al., 2005), Once we warmed up the room, the<br />
participant was seated in an ergonomic chair with arm rest and then stick the sensorial<br />
thermographs in both wrist, close to the median nerve region. After that, the subject was asked to<br />
rest both arms in a flatbed at the ribs height (Kroemer et al., 2001) for about twenty minutes. The<br />
next step in the experiment protocol was to simulate a highly repetitive operation executed in the<br />
textile industry for about 3.5 hours, this period of time representing the longest period of the<br />
workday. The operation involved several movements like reach, take, place and many others.<br />
Several pain symptoms were identified during the experiment. Finally, the sensor thermographs<br />
were removed from both wrist and then analyze the results.<br />
4. RESULTS<br />
The results of all pain symptoms detected during the experiment developed are shown in table 2.<br />
These anomalies were given off by the subject while he was doing the repetitive task. It was so<br />
important to write down the hour, minute and second, so we could link this info to the<br />
temperatures.<br />
Preliminary<br />
1<br />
Preliminary<br />
2<br />
Preliminary<br />
3<br />
Preliminary<br />
4<br />
Table 2. Anomalies detected in the operator<br />
Right<br />
shoulder<br />
pain<br />
x<br />
Left<br />
shoulder<br />
pain<br />
Lower<br />
back<br />
pain<br />
Upper<br />
back<br />
pain<br />
Right<br />
wrist<br />
pain<br />
x x x x x<br />
x x<br />
x x x x<br />
Right<br />
palm<br />
pain<br />
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The corresponding temperature behavior is shown in Figure 1 and 2. If we compare both figures<br />
we can see that both temperature behaviors in both wrists are very but very similar. Three similar<br />
characteristics were identified as a result:<br />
• The temperatures in both writs (maximum stress points) were 33.44˚C and 32.921˚C, and were<br />
reached at similar periods of time, 11:41:14 and 11:49:28 (h:m:s).<br />
• The anomalies in right shoulder started to being shown by the person at the range where were<br />
the highest temperature levels, while doing the operation using both wrists.<br />
• The most aggressive projection of the temperature was approximately at 11:30 and 12:00 in<br />
both wrists.<br />
In both cases the subject beated the pain symptoms on right shoulder, this happened when the<br />
most aggressive projection began to appear, approximately at 11:40. Then at the same time the<br />
temperature projection became less aggressive and began a tendency of decrease.<br />
On the other hand, by adjusting a third order equation it was possible to explain the temperatures<br />
of the person with a coefficient of determination of 91.1% for the left hand wrist and 87.7% for the<br />
right hand wrist.<br />
Figure 1. Adjustment of the curve of left hand wrist<br />
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Figure 2. Adjustment of the curve of right hand wrist<br />
4.2 Preliminary test 2<br />
The corresponding temperature behavior is shown in Figure 3 and 4. If we compare both figures<br />
we can see that both temperature behaviors in both wrists are very similar has shown in the<br />
previous preliminary test. The maximum time of stress of the hands was to similar one from each<br />
other, and based on this we could say the following important points:<br />
The maximum stress points were reached in similar times in both wrists. On left hand wrist at<br />
12:48:24 and the temperature was 34.276˚C and on right hand wrist was 12:48:39 and the<br />
temperature was 34.154˚C. Factors like temperature and time were similar.<br />
Many anomalies were detected on right wrist around 12:33:30 and after one hour on right<br />
palm, and at the same time on lower back.<br />
Anomalies on right shoulder were detected when the maximum temperature stress point was<br />
reached.<br />
On the other hand it was possible to adjust a polinomial third order equation that represents the<br />
subject temperature behavior and as a result a coefficient of determination of 80.5% for the left<br />
hand wrist and 86.8% for right hand wrist.<br />
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Figure 3. Adjustment of the curve of left hand wrist<br />
Figure 4. Adjustment of the curve of right hand wrist<br />
4.3 Preliminary test 3<br />
The corresponding temperature behavior is shown in Figure 5 and 6. If we compare both figures<br />
we can see that both temperature behaviors in both wrists are very similar has shown in the<br />
previous preliminary test and. The maximum time of stress of the hands was similar one from<br />
each other, and based on this we could say the following important points:<br />
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The maximum stress points were reached in similar times in both wrists. On left hand wrist<br />
at 14:11:40 and the temperature was 33.481˚C and on right hand wrist was 14:13:22 and<br />
the temperature was 33.313 ˚C. Factors like temperature and time were similar.<br />
A lower back pain was identified around 12:55:35 and close to the end of the<br />
experimentation a pain on right hand wrist around 14:54:10.<br />
Anomalies on right shoulder were detected when the maximum temperature stress point<br />
was reached.<br />
On the other hand it was possible to adjust a polinomial third order equation that represents the<br />
subject temperature behavior and as a result a coefficient of determination of 90.8% for the left<br />
hand wrist and 94.5% for right hand wrist.<br />
Figure 5. Adjustment of the curve of left hand wrist<br />
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Figure 6. Adjustment of the curve of right hand wrist<br />
4.4 Preliminary test 4<br />
The corresponding temperature behavior is shown in Figure 7 and 8. If we compare both figures<br />
we can see that both temperature behaviors in both wrists are similar has shown in the previous<br />
preliminary test and. The maximum time of stress of the hands was to similar one from each other,<br />
and based on this we could say the following important points:<br />
The maximum stress points were reached in similar times in both wrists. On left hand wrist<br />
at 12:52:14 and the temperature was 33.686˚C and on right hand wrist was 13:03:53 and<br />
the temperature was 33.114˚C. Factors like temperature and time were similar.<br />
A lower back pain was identified around 12:55:35 and close to the end of the<br />
experimentation a pain on right hand wrist around 14:54:10.<br />
Anomalies on right shoulder were detected during the period when the temperature began<br />
to decrease around 13:42:52. Also a pain on right palm was identified around 14:13:43.<br />
At the end of the test a pain on left shoulder was identified around 3:52:40 and also the<br />
pain on right shoulder increased in a several way, this occurred around 3:56:36.<br />
On the other hand it was possible to adjust a polinomial third order equation that represents<br />
the subject temperature behavior and as a result a coefficient of determination of 97.3% for<br />
the left hand wrist and 95.6% for right hand wrist.<br />
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Figure 7. Adjustment of the curve of left hand wrist<br />
Figure 8. Adjustment of the curve of right hand wrist<br />
Taking in account the maximum temperatures reached in the experiment stress points of all the<br />
preliminary test of both hand wrists, we obtained averages for each hand wrist, and the equation 1<br />
shows how to calculate the averages:<br />
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y<br />
n<br />
∑<br />
i=<br />
= 1<br />
n<br />
y<br />
i<br />
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We found out, and based on having similar temperature patterns and stress point periods that<br />
averages were similar too. The average temperature for left hand wrist was y = 33.<br />
72 ˚C and<br />
y = 33.<br />
38˚C<br />
for the right hand wrist.<br />
5. CONCLUSIONS<br />
A preliminary experimental test was undertaken on one hand, for studying the feasibility of using<br />
sensorial thermography on the analysis of repetitive tasks, and on the other hand to identify the<br />
maximum stress point, behavior and temperature patterns as a result of the activity. In particular,<br />
this study shows that the use of the sensorial thermography is appropriate in order to detect<br />
temperature patterns. It is remarkable to mention that in all the test the temperature patterns were<br />
very similar in both hand wrists, independently of the dominant hand of the subject. The<br />
temperature patters were similar for all the tests, but changing its behavior during the days. The<br />
same conditions were taking in account for the entire tests, including the room temperature as the<br />
main element.<br />
On the other hand it was possible to adjust a polinomial third order equation for each test that<br />
represents the subject temperature data behavior and as a result a coefficient of determination to<br />
represent the level of the curve adjustment to data.<br />
6. RECOMENDATIONS<br />
One should recall to this conclusions cannot be considered as universal as far as only one<br />
subject, a subject in good shape, took part in this study. Nevertheless, the conclusions make us<br />
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think of considering a statistical study taking in part more subjects (men and women), to verify if<br />
the temperature patters of several subjects are linked in same way.<br />
7. REFERENCES<br />
E.Y.K, N.G. and E.C., K.E.E., (2008). Advanced integrated technique in breast cancer<br />
Thermography, Journal of Medical Engineering & Technology, Vol. 32, 103-114.<br />
Feldman, F., (1991). Thermography of the hand and wrist: Practical applications, Hand Clinics,<br />
Vol. 7, No.1.<br />
Gold, J., Cherniack, M., Hanlon, A., Dennerlein, T., Dropkin, J., (2009). Skin temperature in<br />
dorsal hand of office workers and severity of upper extremity musculoskeletal disorders, Int.<br />
Arch. Occup. Envior. Health, 82: 1281-1292.<br />
Gold, J., Cherniack, M., Buchholz, B., (2004). Infrared Thermography for examination of skin<br />
temperature in the dorsal hand office workers, Eur J. Apply Physiol 93: 245-251.<br />
Kroemer, E., Kroemer, H., Kroemer. K., (2001). “Ergonomics: How to design for ease and<br />
efficiency”, second edition, Prentice Hall, ISBN 0-13-725478-1, 97-113.<br />
Lopez, R., (1992). Oceanologic Research Institute, Autonomous University of Baja California.<br />
Submarine digital thermograph, Develop and instrumentation, Vol. 3 No.2, 1992<br />
Puig A.A., (1993). Smoking influence in the variations of biochemical, physiological and<br />
performance parameters, Barcelona, Spain.<br />
Zaidi H., TaÏar R., Fohanno S., Polidori G., (2007). The influence of swimming type on the skintemperature<br />
maps of a competitive swimmer from infrared Thermography, Acta of<br />
Bioengineering and Biomechanics, Vol. 9, No.1.<br />
Zontak Alla, Sideman Samuel, Verbitsky Oleg, Beyar Rafael, (1998). Dynamic Thermography:<br />
Analysis of hand temperature, Annals of Biomedical Engineering, Vol. 26, 988-993.<br />
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VIBRATION STUDY TO IMPROVE STRIPPING OPERATION<br />
IN A LITOGRAPHICS COMPANY<br />
Mario Ramírez Barrera ¹, Jorge Valenzuela Corral ¹<br />
Athenea Núñez Sifuentes ˚<br />
¹ Industrial and Manufacturing Engineering Department<br />
˚ Student from Institute of Engineering and Technology<br />
Universidad Autónoma de Ciudad Juárez<br />
mramirez@uacj.mx , jvalenzu@uacj.mx<br />
vain8109@gmail.com<br />
RESUMEN: En una empresa dedicada a la impresión y elaboración de cajas y precisamente en<br />
la operación de striping. o desbarbe que es donde se cortan los excesos o sobrantes de las cajas<br />
después del proceso de sauje (marcado o preformando por medio de prensas), nos encontramos<br />
que en esta operación los trabajadores se encuentran expuestos a los mas importantes factores<br />
de riesgo ocupacional como son frecuencia, esfuerzo energético y mala postura, pero sobre todo<br />
a una sobreexposición de vibración producida por un roto martillo neumático utilizado para quitar<br />
el cartón sobrante o la rebaba de las cajas durante la operación de striping, y es por esto que en<br />
esta investigación se analizo el uso de dicha herramienta y se vio que al utilizar un aislante<br />
adecuado en el mango del roto martillo neumático y los guantes ergonómicos anitimpacto y<br />
antivibración en vez de los de algodón que actualmente proporciona la empresa se reduce al<br />
máximo el estrés de trabajo producido por la vibración, así como también al utilizar el equipo de<br />
protección personal consistente en tapones auditivos, mascarillas y zapatos de seguridad se<br />
mejora considerablemente el entorno del operador y así se podrá reducir considerablemente el<br />
riesgo de adquirir una enfermedad profesional generada por el tipo de trabajo requerido por el<br />
proceso de fabricación del producto.<br />
Palabras Clave: Vibracion, Equipo de protecion personal.<br />
ABSTRACT:The comparative study was made in a company dedicated to fabricate and print<br />
carton boxes. After the carton press forming process there is an operation that removes carton<br />
excess and leftovers which was found that workers are exposed to an occupational risk<br />
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conditions like frequency, body stress and bad postures besides of an overexposure vibrations<br />
condition originated from a pneumatic roto-hammer utilized to remove carton leftovers during the<br />
stripping operation , and that is why this investigation was focused in the use of this pneumatic<br />
tool. After a close analisys of the situation it was found that by adding the proper insulation to the<br />
tool handle and by using anti-impact / anti-vibration ergonomic gloves instead of the normal cotton<br />
gloves provided by the company, the stress condition due to the tool vibrations was drastically<br />
reduced, in addition to this the personal protection equipment was improved by utilizing ear plugs,<br />
mask and safety shoes, and as a result of these actions the work environment conditions were<br />
improved thus reducing the probability of getting a body trauma due to the fabrication process<br />
needs.<br />
Key words: Vibrations, Personnel Protection Equipment.<br />
1. INTRODUCTION<br />
After the carton Fabrication and Printing process there is a stripping operation which consists of<br />
two steps: carton preforming by utilizing a pneumatic roto-hammer and manual removal of<br />
leftovers from cartons located on pallets, figures 1.1 and 1.2 below show the fabrication process<br />
sequence.<br />
Figure 1.1 Preforming of boxes using Figure 1.2 Manual carton leftovers<br />
the pneumatic roto- hammer removal.<br />
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In the operation mentioned above it was found that the workers were exposed to significant<br />
occupational risk conditions such as frequency, body stress and anti-ergonomic postures and also<br />
an overexposure to vibrations for extended periods of time affecting arms and hands due to the<br />
use of this roto-hammer tool, the workers were just using normal cotton gloves, also a survey was<br />
made finding that workers suffer from chronic back ache, weakness sensation of hand grasping<br />
ability known as Accumulative Trauma Disorder (ATD) in tendons and nerves which was<br />
developed due to this working condition for an extended period of time.<br />
2. INVESTIGATION METHODOLOGY<br />
Investigating carefully to get the proper analyzing data in order to improve this workstation, a<br />
Vibrations meter was used ( Bruel & kkjaer”s model vibrotest 60 shown in figure 2.1 ). Vibrations<br />
readings were taken using just regular cotton gloves as shown in figure 2.2 to make the<br />
comparisson against utilizing anti-impact / anti-vibrations ergonomic gloves and also an insulator<br />
material was installed on the roto-hammer handle to help improving this situation. Finally the<br />
readings were taken on both conditions and they are shown on the following tables .<br />
Figure 2.1 Vibrations Analyzer Figure 2.2 Vibrations readings taken at<br />
Utilized in the study Stripping work station.<br />
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The data was carefully analyzed and charts were obtained to compare before and after conditions<br />
(1 µm = .001 mm = 1 x 10 ¯³ mm measuring units were used ) , without cotton gloves, with cotton<br />
gloves, with anti-impact / anti-vibtations gloves and last the insulation on the tool handle.was<br />
added. Chart figure 2.3 shows this data.<br />
Figure 2.3 This chart shows the average of vibration readings using this analyzer . without gloves<br />
(blue), with cotton gloves (purple), With ergonomic gloves (green), with both ergonomic gloves<br />
and handle insulation (red).<br />
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3. RESULTS<br />
Based on the detailed ergonomic analysis made and considering the vibrations condition that the<br />
regular worker is exposed to during extended periods of time , It is strongly recommended to redesign<br />
and relocate this work station to make it safer and easier to handle the material used , and<br />
also it is suggested to break-down this operation in two steps physically separated from each<br />
other (pre forming and manual leftovers removal as shown in figure 3.1) in order to rotate<br />
operators every two hours in each step of the operation , place an anti-fatigue floor mat and at the<br />
same time insulating the handle of the roto-hammer pneumatic tool ( figure 3.2) and also utilizing<br />
anti-vibrations / anti-impact ergonomic cotton gloves / spandex and with akton material on the<br />
hand palm area to reduce the vibrations impact (figure 3.3), in addition to that , safety shoes with<br />
steel must be used at all times , as well ear plugs, and mouth mask to avoid contact with the<br />
carton dusts.<br />
. BEFORE AFTER<br />
ANTES<br />
<strong>DE</strong>SPUES<br />
Figure 3.1 Layout of the stripping operation before and after the improvement showing the<br />
operation separated in two steps and physically separated also.<br />
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Figure 3.2 Insulation of tool handle Figure 3.3 Anti-vibration/impact gloves<br />
4. CONCLUSIONS<br />
The level of vibration due to the use of certain tools can be reduced to avoid a higher<br />
damage to the human body by taking several actions like rotation of workers (Administrative<br />
controls) more often , proper maintenance of tools to prevent malfunctioning, Installation of<br />
anti fatigue floor mats to isolate vibrations from human body,Anti-vibration devices like<br />
plastics or foams adapted to the tools or machines (Engineering controls). And also the use<br />
of personnel protection equipment like anti-vibration / anti-impact gloves. The lesson learned<br />
from this study , most important from all this, is to change or improve Company’s safety<br />
practices culture to protect workers by meeting Official Mexican Safety Norms (nom 017 and<br />
nom 024) at the workplace, and to train , and implement awareness programs aim to<br />
employees through visual and verbal communications medias to make them aware of the<br />
possible body damage due to long exposure of vibration conditions resulting in possible<br />
traumas. (Human administrative controls).*<br />
* Mario Ramirez Barrera (UACJ 2010)<br />
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5. BIBLIOGRAPHY<br />
• Asfahl C ,R. Industrial Safety and Health managment ( 1995) 3ª Edition<br />
editorial Prentice Hall.<br />
• Bailey R. Human Performance Engineering. ( 1989) Prentice Hall.<br />
• International Organization for Standarization (2004) ISO 2631.5.2004 Mechanical vibration<br />
- Evaluation of human exposure to whole body vibration. ISO Switzerland<br />
• Normas Oficiales Mexicanas ( nom 017 y nom 024)<br />
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A Descriptive Study about the Integration of Ergonomic Attributes on the<br />
Selection of Advanced Manufacturing Technology -AMT-<br />
Aidé Maldonado Macías 1, 2 , Arturo Reallyvázquez 1 , Guadalupe Ramírez 1 , Jorge Garcia-<br />
Alcaraz 1 , Salvador Noriega 1<br />
1 Department of Industrial and Manufacturing Engineering<br />
Ciudad Juárez Autonomous University<br />
Ave. del Charro 450 Norte, C.P. 32310<br />
Cd. Juárez, Chihuahua, México<br />
amaldona@uacj.mx<br />
2 Division of Graduate Studies and Research<br />
Ciudad Juárez Institute of Technology<br />
Ave. Tecnológico No. 4090<br />
Cd. Juárez, Chihuahua, México<br />
Resumen: Este artículo presenta un estudio descriptivo sobre la integración de la Ergonomía de<br />
compatibilidad de atributos (ECA) en la selección de la Tecnologia de Manufactura Avanzada<br />
(TMA) entre 30 personas que toman decisiones (TD) de las empresas del sector metal-mecánico<br />
situado en la zona fronteriza de Ciudad Juárez, México. La intención es aumentar el conocimiento<br />
sobre la consideración e importancia de los atributos ergonómicos en la adquisición de TMA.<br />
Además, fueron investigadas algunas de las características del personal que participa en su<br />
funcionamiento, la gestión y la toma de decisiones. Adicionalmente, se identificaron los<br />
procedimientos comunes de evaluación y selección de TMA; se da una clasificación de los<br />
equipos utilizados en estas empresas de acuerdo con el propósito de manufactura.<br />
La metodología expone la ECA en un modelo de atributos múltiples y describe la ECA aplicada<br />
para recabar información sobre las características de la selección de la TMA, selección de<br />
proocesos utilizados en estas empresas. Los resultados muestran que la mayoría de las<br />
empresas realizan algún tipo de diagnóstico para la selección de AMT, pero frecuentemente se<br />
omiten o descuidan los atributos ergonómicos. Sin embargo, los TM reconocen que al tomar en<br />
consideracion los atributos ergonomicos en la selección de TMA puede proporcionar una ventaja<br />
estratégica al facilitar y promover condiciones operativas más seguras en estos lugares de trabajo<br />
y lograr una mejor aplicación de esta tecnología también. Asimismo, los resultados indican que es<br />
casi tan frecuente encontrar en estas empresas la tecnología CNC como la tecnología tradicional<br />
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y una tendencia cada vez mayor para incrementar las inversiones en tecnología de robots y<br />
prototipado rápido. Además, el genero masculino es predominante en el personal operativo y<br />
administrativo relacionado con TMA y el personal operativo promedia una antigüedad en un rango<br />
de 4-7 años.<br />
Palabras clave: Ergonomia de Compativilidad de Atributos, Tecnología de Manufactura<br />
Avanzada, Toma de Decisiones, Encuesta de compatibilidad ergonómico para TMA<br />
Abstract: This paper presents a descriptive study about the integration of Ergonomic<br />
Compatibility Attributes (ECA) on the selection of Advanced Manufacturing Technology (AMT)<br />
among 30 Decision Makers (DM) from enterprises of the metal-mechanical sector located in the<br />
borderland of Juarez City, Mexico. It is meant to increase knowledge about the consideration and<br />
importance of ergonomic attributes on the acquisition of Advanced Manufacturing Technology<br />
(AMT). Also, some characteristics of the personnel involved in its operation, management and the<br />
decision making processes were investigated. Additionally, common procedures for evaluation<br />
and selection of AMT were identified; a classification of the equipment used in these companies is<br />
provided according to the manufacturing purpose.<br />
The methodology exposes the ECA in a multi-attribute model and describes the Ergonomic<br />
Compatibility Survey (ECS) applied for gather information about the characteristics of the AMT<br />
selection processes used in these companies. The results show that most of the companies do<br />
perform some kind of diagnosis for AMT selection, but ergonomic attributes are often omitted or<br />
neglected among them. However, DM recognize that ergonomic attributes consideration in AMT<br />
selection may provide a strategic advantage in the way it would facilitate and promote safer<br />
operative conditions in these workplaces, and a more successful implementation of this<br />
technology as well. Also, results explain that CNC technology is almost as frequent to find in these<br />
companies as traditional technology and a growing trend to increment the investments in rapid<br />
prototyping technology and robots can be observed. Additionally, male gender is predominant in<br />
the operative and management personnel related with AMT and operative personnel average<br />
seniority is in a range of 4-7years.<br />
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Keywords: Ergonomic Compatibility Attributes, Advanced Manufacturing Technology, Decision<br />
Making Processes, Ergonomic Compatibility Survey for AMT.<br />
1. INTRODUCTION<br />
This section presents the problem description, the objectives of this investigation and finally the<br />
justification and the scope.<br />
1.1 Problem Description<br />
According to the Metal-Mechanic Industry Directory 2008 (Directorio de la Industria Metal-<br />
Mecánica, DIMM, by its initials in Spanish) in Juarez City, there are approximately 200 companies<br />
in the field of Metal-Mechanic Industry, which represents an important source of jobs for the city.<br />
Thus, it is believed that there is substantial amount of workers engaged in the use of AMT.<br />
However, studies about the characteristics of the personnel and employees related with the<br />
operation and management of AMT and the integration of safety and ergonomic attributes in the<br />
decision making processes are scarce locally.<br />
It is well known that managers and DM face the problem of selection of many AMT<br />
alternatives; and there are multiple attributes involved in making a good decision, so it is difficult to<br />
consider all in their totality. In this way, this research pretends to explore the integration of ECA on<br />
the selection of AMT among 30 DM in local industries and to promote the consciousness about<br />
the benefits of ergonomics’ implementation.<br />
1.1.1 Objectives<br />
The objectives that arise in this work are divided into three specific and one general goal, which<br />
are explained below:<br />
1.1.1.1 General Objective<br />
Increase knowledge about the consideration of ergonomic attributes on the acquisition of<br />
Advanced Manufacturing Technology (AMT) by means of a descriptive study and the application<br />
of the ECS to 30 DM in local companies.<br />
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1.1.1.2 Specific Objectives<br />
Describe some important characteristics of the personnel involved in its operation, management<br />
and in the decision making processes for AMT acquisition.<br />
Identify common procedures for evaluation and selection of AMT.<br />
Provide a classification of the equipment used in these companies according to the manufacturing<br />
purpose.<br />
Increase knowledge about the reasons they may or may not include ergonomic and safety<br />
attributes on their decision making processes.<br />
1.1.2 Justification and Scope<br />
This research will provide information to managers and investors of the Metal Mechanic Industry<br />
about the integration of ergonomic attributes on the selection of AMT, which may have been<br />
previously obviated. According to Helander (2006), companies that take into account the<br />
ergonomic attributes on the selection process of AMT will result in safety, productivity and<br />
satisfaction of their workers.<br />
This work was made in the Metal Mechanic Industry in Ciudad Juarez, Mexico, where an ECS<br />
was applied to DM to know some characteristics of their planning and selection processes of AMT<br />
and the personnel involved in such processes.<br />
2. LITERATURE REVIEW<br />
Ergonomic and safety aspects are significant for the design and operation of complex<br />
manufacturing systems like the ones related with AMT. These are being under estimated for the<br />
control of injuries and safety problems in the Manufacturing Industry (Karwowski, 1990, 2005).<br />
According to the Bureau of Labor Statistics of the United States, the Mexican Social Security<br />
Institute (IMSS), the European Agency for Safety and Health at Work, and the Report of Labor<br />
and Social Trends in Asia 2006 nowadays the Manufacturing Industry occupies one of the top five<br />
industries with the highest number of injuries, illnesses, days away from work, along with other<br />
important statistics worldwide. Additionally, in Mexico the operation of tools and machines is one<br />
of the top five occupations that report the highest numbers of these events also. However, there<br />
are difficulties to relate these events with the operation of AMT, due to insufficient information and<br />
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lack of attention to this topic (Maldonado, 2009). Important authors recognize that even when AMT<br />
was introduced among others reasons to reduce safety risks and hazards for humans, new and<br />
more critical ergonomic and safety risks have been detected since its introduction in<br />
manufacturing processes (Nicolaisen, 1995; Karwowski et. al., 1988; Karwowski and Salvendy,<br />
2006; Sugimoto et. al., 1985).<br />
In this way, managers and DM may have underestimated Human Factors and Ergonomics<br />
attributes in their decision in the way priority is given to other factors. Also they are unaware of<br />
these attributes and their benefits. Such ignorance has serious consequences for companies and<br />
their workers, since the operators work under physical and mental stress, eventually develop<br />
musculoskeletal trauma disorders and injuries for life, which represents large losses for jobs and<br />
businesses (Prado, 2001).<br />
3. METHODOLOGY<br />
The methodology presents the description of ECA and the ECS.<br />
3.1 Ergonomic Compatibility Attributes<br />
Ergonomic Evaluation of AMT is not an easy topic since ergonomic requirements (attributes) are<br />
not clearly determined in the literature and disperse, also it implies quantitative and qualitative<br />
aspects and its complexity and vagueness make an even harder problem to resolve. For<br />
Karwowski (2005), advanced technologies with which human interaction constitute complex<br />
systems that require a high level of integration, he considers that Ergonomic Compatibility<br />
Attributes of AMT have to focus in the design integration of the interactions between hardware<br />
(computer-based technology), organization (organizational structure), information system, and<br />
people (human skills and training). This was the foundation of the literature search, but also<br />
Corlett and Clark (1996) ergonomic guide for machine design was used. In this way, ergonomic<br />
compatibility evaluation main attributes (ECMA) for AMT, were divided into five parts: human skills<br />
and training compatibility (A11), physical work space compatibility (A12), usability (A13),<br />
equipment emissions (A14) and organizational requirements (A15). The main attribute A11<br />
includes two sub-attributes: skill level compatibility (A111) and training compatibility (A121). The<br />
main attribute A12 includes five sub-attributes: access to machine and clearances (A121),<br />
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horizontal and vertical reaches (A122), adjustability of design (A123), postural comfort of design<br />
(A124), physical work and endurance of design (A125). The main attribute A13 includes seven<br />
sub-attributes: controls design compatibility (A131), controls’ physical distribution (A132), visual<br />
work space design (A133), information load (A134), error tolerance (A135), man machine<br />
functional allocation (A136), design for maintainability (A137). The main attribute (A14) includes<br />
four sub-attributes: temperature (A141), vibration (A142), noise (A143), residual materials (A144).<br />
The main attribute (A15) includes two sub-attributes: rate of work machine compatibility (A151)<br />
and job content machine compatibility (A152).<br />
3.2 Ergonomic Compatibility Survey<br />
An Ergonomic Compatibility Survey (ECS) was designed for collect the information of the<br />
evaluation of AMT alternatives. The ECS has two versions; one of these versions was designed to<br />
be answered by experts and the other one to be answered by DM. For this work it will be analyzed<br />
the second version (DM). DM’ subjective opinions were needed. The ECS consists on 72<br />
questions but for the effects of this work only the first 22 questions were analyzed covering the<br />
sufficient information to make a descriptive study.<br />
3.2.1 Companies’ General Data<br />
The general data of the companies is requested in the first section of the ECS. Information<br />
includes average occupation and the respective gender. Also the workers’ average age for each<br />
gender is requested and workers’ average seniority to each gender. Finally, the kind of AMT used<br />
in the company is inquired.<br />
3.2.2 Characteristics of the Planning and Selection Process of Advanced Manufacturing<br />
Technology (AMT)<br />
This part includes 17 questions. This section aims to know some characteristics of the planning<br />
process for the acquisition of ATM in the company and who participate in the decision making.<br />
The first 3 questions refer to who makes the final purchasing decision of AMT. The next 3<br />
questions refer to how the AMT is identified and how the selection process is carried out. Finally,<br />
through the last 13 questions the integration of ergonomic and safety attributes on the selection<br />
process of AMT can be observed.<br />
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4. RESULTS<br />
This section presents the results obtained of the ECS described above.<br />
4.1 Results of Companies’ General Data<br />
This section shows the results of general data company.<br />
4.1.1 Gender and average occupation<br />
Companies of the survey occupy mainly male workers in all positions. According to the survey,<br />
male gender is preferable due to the nature of the work and the applied force that is required in<br />
some activities. The majority of female personnel found in these companies usually have<br />
administrative positions. Figure 1 shows these results. Additionally, average occupation is of 46<br />
workers among the participating companies.<br />
Number of Employees<br />
female<br />
14 %<br />
Figure 1. Gender of employees in the Metal Mechanical Sector<br />
4.1.2 Average age of employees<br />
Figure 2 shows that male workers employed have on average 29.76 years of age and female<br />
workers have on average of 30.80 years of age.<br />
female<br />
30.80<br />
Figure 2. Employees’ average age in the Metal Mechanic Sector<br />
Sociedad de Ergonomistas de México, A.C. 143<br />
male<br />
86 %<br />
Average Age<br />
male<br />
29.76
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4.1.3 Average Seniority of employees<br />
Figure 3 shows that the average seniority of male workers is 6.79 years while female workers<br />
have average seniority of 4.03 years. This results show also that male gender is still being<br />
preferable above female gender in these companies.<br />
Figure 3. Average seniority in the Metal Mechanical Sector<br />
4.1.4 Equipment Used in the Metal Mechanical Sector Companies<br />
Participating companies present a variety of equipment. Equipment was classified into seven<br />
categories according to the manufacturing purpose: CNC Technology, Cutting Technology,<br />
Traditional Technology, Molding of Plastic Technology, Cleaning and Treatment of Metals<br />
Technology, Welding Technology, and Others.<br />
As it is shown in Figure 4, actually CNC Technology is almost as frequent to find as<br />
traditional Technology. Finally, a growing trend can be observed on equipment such as electrical<br />
discharge machines, flexible manufacturing cells, robots, robo-drills, and progressive die press<br />
found in the Others classification.<br />
180<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
160<br />
female<br />
4.03<br />
12<br />
Average Seniority<br />
161<br />
Sociedad de Ergonomistas de México, A.C. 144<br />
21<br />
male<br />
6.79<br />
CNC Cutting Traditional Molding of Cleaning Welding<br />
Technology Technology Technology Plastics and Technology<br />
Technology Treatment<br />
of Metals<br />
Technology<br />
Figure 4. Classification of the Equipment Used in the companies<br />
27<br />
25<br />
64<br />
Others
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
4.2 Important Characteristics of the Selection Processes for AMT acquisition.<br />
This section shows the results of some characteristics of the planning and selection processes<br />
found in these companies.<br />
4.2.1 Planning Processes for the acquisition of AMT in the Industry<br />
Figure 5 shows that 77 % of the companies surveyed do perform some kind of planning processes<br />
for the acquisition of AMT; this indicates the relevance of a good decision making about AMT.<br />
Companies that do perform Planning<br />
Processes for AMT<br />
Sociedad de Ergonomistas de México, A.C. 145<br />
77 %<br />
YES<br />
Figure 5. Percentage of Companies that do perform Planning Processes for AMT acquisition<br />
In these companies, the planning processes performed for AMT acquisition are mainly part of<br />
engineering projects; this means that projects play an important role due to the specifications<br />
accomplishment on the selection of AMT. Also, in most of these companies the planning<br />
processes are executed only by the high management. Figure 6 shows the kind of personnel<br />
involved in the planning process for the acquisition of AMT.<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
4<br />
Management<br />
Group<br />
Sessions<br />
10<br />
E ngineering<br />
Project<br />
P lanning<br />
4<br />
23 %<br />
NO<br />
Upgrade of<br />
E quipment<br />
R equirements<br />
2<br />
Process<br />
E xecuted by<br />
Corporative<br />
Personnel<br />
7<br />
Process<br />
E xecuted by<br />
High<br />
Managemet<br />
Figure 6. Planning Process Execution for AMT acquisition<br />
Figure 7 shows that Executive and Administrative Personnel are mainly involved in the planning<br />
and selection processes; also in 35 % of the companies a group composed by executive,<br />
administrative and operative personnel conduct the decision for AMT acquisition.
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
35 %<br />
7 %<br />
17 %<br />
41 %<br />
E xecutive personnel<br />
Adminis trative pers onnel<br />
Operative pers onnel<br />
A group of the three<br />
Figure 7. Personnel who participate on the Planning Process for AMT acquisition<br />
Companies have different search methods for acquiring AMT. Some companies use two or three<br />
of this methods at the same time. Figure 8 shows that the use of internet web service and vendors<br />
casting are the most extended ways for search and acquire AMT, followed by benchmarking and<br />
equipment’s exhibit. Also the use empirical knowledge is included in the Others category.<br />
20<br />
18<br />
16<br />
14<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
13<br />
Vendors<br />
Casting<br />
7<br />
Equipment's<br />
E xhibit<br />
Sociedad de Ergonomistas de México, A.C. 146<br />
18<br />
Internet W eb<br />
Service<br />
8<br />
B enchmarking Others<br />
Figure 8. Searching Methods for AMT acquisition<br />
4.2.2 Application of Evaluation Processes for the selection of AMT<br />
Once the AMT has been identified, it is recommended to perform some kind of diagnosis<br />
processes to ensure that company’s expectations are met and avoid high costs. Figure 9 shows<br />
most of the companies do perform some kind of evaluation or diagnosis processes for AMT<br />
selection.<br />
Companies that perform some kind<br />
of evaluation<br />
20 %<br />
NO<br />
Figure 9. Companies that perform some kind of evaluation<br />
Among these companies, the processes are supported by experts in the first place; then by the<br />
use of checklists and standardized corporative formats, only a few use some specialized software;<br />
and one company uses only the experience (Figure 10). Companies that omit evaluation<br />
processes assume that the requirements are included by default in the equipment.<br />
80 %<br />
YES<br />
9
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20<br />
18<br />
16<br />
14<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
13<br />
Vendors<br />
Casting<br />
7<br />
Equipment's<br />
E xhibit<br />
Sociedad de Ergonomistas de México, A.C. 147<br />
18<br />
Internet W eb<br />
Service<br />
8<br />
B enchmarking Others<br />
Figure 10. Diagnosis Methods for the selection of AMT in the Metal Mechanic Sector<br />
These results show that most companies recur to experts to enhance their decisions.<br />
4.2.3 Ergonomic Attributes on the Planning Process<br />
Figure 11 shows that slightly more than a half of the surveyed companies that do apply some kind<br />
of evaluation process also consider ergonomic attributes on the selection of AMT. It is inferred by<br />
the attitude shown by managers and DM during interviews that 45% of them are unaware of the<br />
ergonomic attributes that may be involved in the evaluation, even some of them had not even<br />
heard about the topic.<br />
Ergonomic Attributes on the Planning<br />
Process<br />
45%<br />
NO<br />
55%<br />
YES<br />
Figure 11. Ergonomic Attributes on the Planning Process<br />
Ergonomic attributes included in the diagnoses of the equipment were diverse, but it was<br />
emphasized that all managers are looking for comfort for their operative personnel through proper<br />
postures and less effort. It was also important for managers the adjustability of the equipment.<br />
Additionally, usability of the equipment is required since they look for easiness of use in<br />
equipment and tools, also, Compatibility with Human Skills and Training seems to be the most<br />
important ergonomic attributes for DM on the selection of AMT according to Maldonado (2009).<br />
About DM who do not consider ergonomic attributes in the diagnoses, they argue that the priority<br />
on AMT must be on the technical aspects, costs and lead times. Also the main reason to do so is<br />
the lack of knowledge about Ergonomics and the need of a pragmatic model or method that<br />
facilitates their integration in decision making.<br />
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On the other hand, safety attributes are included in the evaluation processes in almost all<br />
companies. Among the 30 companies surveyed, only one refused to include safety attributes in<br />
the diagnosis. Figure 12 shows this fact. It is deduced that safety attributes are much better known<br />
than Ergonomic Attributes among DM.<br />
Safety Attributes on the Planning Process<br />
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3%<br />
NO<br />
97%<br />
YES<br />
Figure 12. Safety Attributes on the Planning Process<br />
In this research, most of the companies recognized that the integration of ergonomic attributes<br />
can become a strategic advantage for competitiveness; and for DM the combination of<br />
ergonomics and safety attributes would enhance the implementation of AMT, therefore it is easier<br />
to derive the benefits that both aspects generate. Figure 13 shows this fact.<br />
Companies that consider Ergonomics<br />
and Safety attributes help to a best<br />
implementation of AMT<br />
17 %<br />
NO<br />
Figure 13. Companies that find a strategic advantage of Ergonomics<br />
5. CONCLUSIONS AND RECOMMENDATIONS<br />
It can be concluded that most companies surveyed do perform some kind of planning and<br />
selection processes for AMT acquisition. However, the integration of ergonomic and safety<br />
attributes are usually neglected in the diagnosis and selection processes for acquiring AMT. The<br />
final decision about AMT acquisition is lead by the high management personnel and is strongly<br />
supported by experts. It was found appropriate by DM to increase their knowledge about the<br />
ergonomics aspects that can be taken into account to support their decision due to they consider<br />
Ergonomic and Safety attribute as a strategic advantage. The AMT which predominate in the<br />
83 %<br />
YES
Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010<br />
Metal Mechanic Sector in Juarez, Mexico has gradually been replacing traditional technology.<br />
Different practices for decision making about AMT among companies were studied, making clear<br />
that engineering projects are one of the most important reasons to replace or acquire equipment.<br />
Finally, it was analyzed the methods used by companies to identify and search AMT, where the<br />
internet web service was the method preferred by DM due to its convenience.<br />
It is recommended to extend this study among macro enterprises which have higher occupation<br />
and may have records of accidents, injuries, days away from work and other events related with<br />
the operation of AMT. This may help to obtain more accurate results of the importance of the<br />
integration of ergonomic attributes on the selection of AMT.<br />
6. REFERENCES<br />
Corlett E. N. y Clark T.S. (1995). The Ergonomics of Workspaces and Machines, 2a. Edición,<br />
Taylor and Francis.<br />
European Agency for Safety and Health. 2007. “Work ILO Facts European Agency for Safety and<br />
Health at Work”,<br />
http://www.ilo.org/public/english/standards/relm/ilc/ilc90/pdf/rep-v-1.pdf.<br />
Helander, M. (2006). A guide to human factors and ergonomics, 2 nd Edition, Taylor & Francis<br />
Group, pp. 8.<br />
IMSS. 2007. “Estadísticas laborales del Instituto Mexicano del Seguro Social”,<br />
http://www.siicyt.gob.mx/siicyt/Principal.do?urlc=4,14.<br />
Karwowski W. 1990. “Injury control and worker safety in integrated manufacturing systems”,<br />
Unpublished Technical Report, Center for Industrial Ergonomics, University of Louisville,<br />
Louisville, Kentucky, United Sates of America.<br />
Karwowski W. 2005. “Ergonomics and human factors: the paradigms for science, engineering,<br />
design, technology and management of human-compatible systems 1 ”, Ergonomics, Vol.48, No.<br />
5, Pgs. 436-463.<br />
Karwowski, W., Parsaei, H.R., Nash, D.L., and Rahimi, M. (1988). Human perception of the work<br />
envelope of an industrial robot, in Ergonomics of Hybrid Automated Systems, W. Karwowski, H.<br />
R. Parsaei, and M. R. Wilhem, Eds., Elsevier, Amsterdam, pp. 421-428.<br />
Karwowski, W. and Salvendy, G. (2006). Handbook of human factors and ergonomics, John Wiley<br />
& Sons Inc., United States of America.<br />
Labour and Social trends in Asean. 2007. “Labour and Social trends in Asean<br />
countries”,http://www.ilo.org/public/english/region/asro/bangkok/library/download/pub07-04.pdf.<br />
Maldonado Macías Aide Aracely, (2009). Tesis Doctoral, Instituto Tecnológico de Cd. Juárez.<br />
Diciembre 2009.<br />
Maldonado Aide, Noriega Salvador, Díaz Juan J., (2009). Ergonomic Compatibility Survey for the<br />
Evaluation of Advanced Manufacturing Technology, Proceedings of the International Safety and<br />
Occupational Ergonomics Conference.<br />
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Nicolaisen. P. (1985). Occupational safety and industrial robots-present stage of discussion within<br />
the tripartite Group on robotic safety, in Robot Technology and Applications,-Proceedings of the<br />
1 st Robotics Europe Conference, Brussels June 27-28, 1984, K. Rathmill, P. MacConaill, S.<br />
O’Leary, and J. Brown, Eds., Springer-Verlag, Berlin, pp. 74-89.<br />
Prado León, L. (2001). Ergonomía y Lumbalgias ocupacionales.<br />
Sugimoto, N., and Kawaguchi, K. (1985). Fault-tree analysis of hazards created by robots, in<br />
Robot Safety, M. C. Bonney and Y.F. Yong, Eds, Spreinger-Verlag, KFS, Berlin, pgs.83-98.<br />
U. S. Bureau of Labor Statistics. 2005. “Survey Occupational Injuries and Illnesse Summary<br />
Estimates Package (Appendix B)”.<br />
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Remote Ergonomics Evaluations in the Office<br />
Jeffrey E. Fernandez 1 , Gabriel Ibarra-Mejia 2 , and Brandy F. Ware 1<br />
1 JFAssociates, Inc<br />
Vienna, VA 22181<br />
Corresponding author’s email: jf@jfa-inc.com<br />
2 University of Texas at El Paso<br />
Department of Public Health Sciences<br />
College of Health Sciences<br />
El Paso, TX<br />
Resumen: Existe una prevalencia de trastornos musculo-esqueléticos, tales como el Síndrome<br />
del Túnel de Carpo en el medio ambiente de oficinas, debido a la presencia de factores de riesgo<br />
de lesión. Muy a menudo, los factores causales de incomodidad pueden ser detectados a través<br />
de una evaluación del lugar de trabajo realizada por un individuo calificado, como lo es un<br />
ergonomista. Gran cantidad de compañía y empresas no cuentan el personal con la experiencia<br />
para realizar estas evaluaciones en forma interna, de tal manera que recurren a contratar<br />
ergonomistas calificados. El creciente uso de la tecnología disponible en los lugares de trabajo y<br />
la disminución de tiempos de entrega al realizar evaluaciones de lugares de trabajo, ha producido<br />
que el ergonomista adopte nuevos abordajes para la solución de problemas relacionados con la<br />
ergonomía. Este documento plantea la aplicación de evaluaciones ergonómicas de oficina<br />
realizada a distancia (remotas) a través de un ergonomista virtual.<br />
Abstract: In the office environment, musculoskeletal disorders such as carpal tunnel syndrome<br />
are prevalent due the presence of injury risk factors. More often than not, the factors causing<br />
discomfort can be accessed through a workplace evaluation performed by a qualified individual,<br />
such as an ergonomist. Many companies do not have the expertise to conduct evaluations inhouse<br />
and hire a qualified ergonomist. The increasing use of enabling technology in the workplace<br />
and shrinking delivery times for workplace evaluations has necessitated that ergonomists adopt<br />
new approach to solving ergonomics related problems. This paper discusses the application of<br />
remote ergonomic evaluations of office workstations through a virtual ergonomist.<br />
Keywords: ergonomic evaluation, remote, office ergonomics<br />
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1. BACKGROUND<br />
The repetitive nature of office work (long term keyboard and mouse use) or inappropriately<br />
adjusted office equipment (i.e. chair and desk) could cause discomfort or injuries. Injuries often<br />
begin as discomfort and are caused by exposure over a period of time to the repetitive nature of<br />
work (long term keyboard and mouse use) or inappropriately adjusted equipment (i.e. chair and<br />
desk). More often than not, the factors causing discomfort can be accessed through a workplace<br />
evaluation performed by a qualified individual, such as an ergonomist.<br />
When the ergonomist visits the workplace, he/she interviews the client, collects<br />
measurements of the client and workplace, and makes recommendations. During the on-site<br />
evaluation, the client must host the ergonomist by meeting them, escorting them to their work<br />
area, and spending undivided attention while the ergonomist is there. This time away from their<br />
work decreases productivity. From the ergonomist’s perspective, there is time spent commuting,<br />
and collecting measurements at the workplace. In both of these cases, the cost is transferred to<br />
the client. The speed of business today leads clients to expect a shorter delivery time for the<br />
evaluations. Due to these factors, there is a need for a cost effective approach to solving office<br />
ergonomics related problems.<br />
One approach is to provide ergonomic evaluations through a virtual ergonomist (i.e. not onsite).<br />
The evaluation is initiated by client contacting the service provider and concludes with the<br />
virtual ergonomist following up with the client after recommending the necessary modifications.<br />
This paper outlines the process employed by a virtual ergonomist for conducting an ergonomic<br />
evaluation of an office workstation.<br />
2. PROCESS AND DISCUSSION<br />
The evaluation of the workstation includes all of the same basic elements of an in-person<br />
evaluation along with the same deliverables. This process was initially implemented in paper /<br />
electronic form using email for data transfer. The evaluation process flow is shown in Figure 1.<br />
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The first stage of the process is the initial contact with the client. The assessment sequence<br />
is generally triggered an employee or other individual (e.g. health services, management)<br />
requesting an evaluation of the workstation in response to a perceived issue such as discomfort or<br />
pain (reactive).<br />
The next stage includes obtaining background information, workstation and anthropometric<br />
measurements (as shown in a pictorial diagram that is provided), body part discomfort rating, and<br />
digital data from the client. The still photos and /or video clips of the work area and the activities<br />
being performed is the additional piece of data that is critical to the successful completion of a<br />
remote ergonomics evaluation. The still images should be of the client in their work environment<br />
simulating work tasks from different angles and locations to adequately demonstrate the postures<br />
obtained during work. When possible, video footage should also be obtained of the real-time<br />
performance of work (or simulated work) to demonstrate frequency information. A good rule of<br />
thumb is that video data should be 5-10 minutes in length and include all significant tasks<br />
performed by the client.<br />
During the time the ergonomist reviews the data provided by the client, there might be a need<br />
to contact the client to clarify or obtain more information about the discomfort, tasks, or<br />
workstation setup. During the evaluation, at least three opportunities for information exchange via<br />
phone call or video conference should be provided. The initial interaction should be to clarify the<br />
initial background information provided and educate the client on proper ergonomic setup. The<br />
second interaction should be to review the work related risk factors identified through the<br />
evaluation. At this time, the ergonomist will review the recommendations and discuss possible<br />
options for modification to a setup. The third interaction should occur after the workstation<br />
modifications have been made by the client. This interaction may be visual (e.g. include photos or<br />
video) in addition to verbal. This final stage of the evaluation is a very important element of the<br />
process. A follow-up is essential to ensure that the end-user neither experiences any discomforts<br />
similar to the ones before the workstation modification nor does he/she develop any additional<br />
discomforts. At this time, the virtual ergonomist reviews the worksite for completeness of the<br />
recommendations and to ensure that no other risk factors are present. Additional follows may be<br />
scheduled as per need.<br />
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The output of a remote ergonomic evaluation will be very similar to those generated with a<br />
traditional, on-site evaluation. The output in a written report should include a review of the current<br />
status, a listing of the observed risk factors, and a list of recommended changes both short term<br />
and long term.<br />
Figure 1. Process Flow for an Ergonomic Office Evaluation through Virtual Ergonomist (Fernandez<br />
et. al, 2009)<br />
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A remote system requires an understanding of the information needed, comprehensive<br />
mastery of the fundamental office ergonomics principles and their application, and an appropriate<br />
interpretation of the data provided by client. In most cases, only a certified and qualified<br />
ergonomist(s) is an appropriate choice for these evaluations. The affect of such remote<br />
evaluations could save clients money, decrease carbon footprint, and improve the transfer of<br />
ergonomic information to remote locations.<br />
The most advanced application of a virtual ergonomist involves the use of the internet as a<br />
platform for providing the aforementioned services. A website with interactive screens is required<br />
to solicit information. Additionally, the website should provide the user with the capability to upload<br />
pictures and videos for review. The interactive screens of the web site should parallel the flow of<br />
the remote evaluation.<br />
3. TESTING AND IMPLEMENTATION<br />
This process has been tested in the U.S. A. and Mexico. The testing involved the<br />
participation of clients in the same manner as the end product was intended. Throughout the<br />
testing, input was received on the nature of the questions that were asked and the<br />
appropriateness of the directions given. As a result of the testing, refinements were made to the<br />
processes and checklists to improve usability and ensure comprehensive collection of relevant<br />
data.<br />
4. REFERENCES<br />
Fernandez, J.E., Ware, B.F., Kumar, A., and Subramanian, A. (2009). Office Ergonomics<br />
Assessment Through Virtual Ergonomist. Proceedings of the 14 th International Conference<br />
on Industrial Engineering, Theory, Applications and Practice. Anaheim, CA.<br />
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COMPARATIVE ANALYSIS BETWEEN AN ERGONOMIC EVALUATION AND THE USERS'<br />
SATISFACTION OF NEW EDUCATIONAL CENTERS<br />
B.Eng. Martín Daniel Del Sol Rangel 1 , M.Eng. Manuel Sandoval Delgado 2<br />
POSTGRADUATE <strong>DE</strong>PARTMENT AND INVESTIGATION<br />
INSTITUTO TECNOLÓGICO <strong>DE</strong> HERMOSILLO<br />
Tecnológico Ave. And Periférico Poniente Blvd, Sahuaro<br />
HERMOSILLO, SONORA, 83170<br />
Daniel-delsol@hotmail.com, msandoval@ith.mx<br />
1 INTRODUCTION<br />
Globalization is transforming all the products in comfort, while clients, current or potential, are<br />
constantly increasing demands and expectations, products seemed fine yesterday, today may not<br />
be satisfactory, it is then that to win and retain customers, organizations need to find something to<br />
turn into a competitive advantage, that element is the quality. All organization looking to be more<br />
competent and always at the forefront, offering the best to its customers and users, resulting in a<br />
successful project.<br />
The managing a project involves the application of knowledge, skills, tools, and techniques to<br />
project activities so that they meet or exceed the needs and expectations of the stakeholders of a<br />
project. The factors for the success of the project are the set of circumstances, facts, or influences<br />
which contribute to the project results. The success of the projects we perceive from two<br />
approaches, one micro which is represented by the cost, delivery time and meet customer<br />
specifications, the other is the macro that represents the total satisfaction of the user who uses it.<br />
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The present work of investigation is a comparative analysis between studies of "Verification of the<br />
environmental conditions in the facilities design of new buildings at the preschool level creation in<br />
the education sector in Hermosillo, Sonora" and "Anthropometry and verification of facilities design<br />
buildings at the preschool level ups in the education sector in Hermosillo, Sonora”, against the<br />
results of the study “Factors influencing the satisfaction of user of schools newly created basic<br />
level in Hermosillo, Sonora ", There are no studies that serve as background or base for departure<br />
because it is a recent project of the Sonora Institute for Educational Infrastructure, which reports<br />
to the State Government and which has never measured the satisfaction of users of such works<br />
public.<br />
2 OBJECTIVES<br />
Making a comparison between the perceptions of the user against the measurements obtained in<br />
the two studies mentioned above, concurrent, and find out if its result compared with the official<br />
standards and anthropometric measures for installations in schools, have a value of significance<br />
in user satisfaction. Be conducted only in the municipality of Hermosillo, Sonora, in the four<br />
schools of this type found in the city.<br />
3 METHODS<br />
Was determined primarily based sample, in this case 32 which is the total of people working in<br />
these institutions, being interviewed teachers, administrative and support, were interviewed by<br />
school staff, as direct users , to hear his perspective from the macro environment, as well as<br />
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some people working in the Sonora Institute of Educational Infrastructure to meet their<br />
expectations of the quality they deliver these works, that is, from the micro environment, with<br />
this design A pilot survey to discover the needs or problems that arose within those premises<br />
was a validation of the survey was applied in only one school, and was designed to be<br />
analyzed a survey based on certain items required for research using the method Servqual,<br />
which defines service quality as the difference between actual perceptions by users and is a<br />
multi-scale instrument that has a high level of reliability and validity, that any organization can<br />
use to better understand the expectations and perceptions about service users. The model<br />
includes two dimensions of expectations: expectations desired (which I'd like in ideal terms)<br />
and appropriate expectations (the acceptable level of service expected). Besides this is divided<br />
into headings such as, visual perception and environmental design, ambient conditions, safety,<br />
and responsiveness in terms of failures and complaints in the facility.<br />
Thus, a survey was designed to apply well-defined in the entire field of study, ie, universal primary<br />
education schools and kindergartens in the newly created municipality of Hermosillo.<br />
Respondents were only administrative and teaching staff, these being the ability to direct users to<br />
answer the survey because students are also users but do not have the maturity to respond<br />
coherently to the research questions.<br />
4 RESULTS<br />
In implementing the surveys, we will realize the factors that influence the level of satisfaction of<br />
users of each of these schools, we can compare each of them, finding differences and similarities<br />
between themselves and in turn, and by type of primary or preschool, and thus may provide<br />
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feedback to those implementing this project, and be able to carry not only the success of the micro<br />
environment but also from the macro. As well as we can compare these plots obtained in the<br />
surveys carried out against the measurements obtained in the other two parallel research this and<br />
see whether they comply with official standards, and then be detected if it affects the user<br />
satisfaction.<br />
Figure 1. Results obtained in the survey research, “Factors are<br />
influencing the satisfaction of users of schools newly created basic<br />
level in Hermosillo, Sonora”, in the Kindergarten “Los Arroyos”.<br />
Figure 2. Results obtained in the survey research, “Factors are<br />
influencing the satisfaction of users of schools newly created basic<br />
level in Hermosillo, Sonora”, in the Elementary School “Los Arroyos”.<br />
The question 6, is related to the lighting of the classroom, if considered appropriate for the proper<br />
performance of students and teachers, including the cataloged in the case of kindergarten as<br />
excellent and as good in the Elementary School, giving it a rating 10 and 8 respectively. Here we<br />
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see the data in the study of "Verification of environmental conditions in the facility design of the<br />
buildings at the preschool level ups in the education sector in Hermosillo, Sonora."<br />
Table 1. Results obtained in the ergonomic study research “Verification of<br />
environmental conditions in the facility design of the buildings at the preschool<br />
level ups in the education sector in Hermosillo, Sonora” in Kindergarten “Los<br />
Arroyos”.<br />
The minimum level of lighting according to the NOM 025 analyzed, the minimum standard of this<br />
factor must be 300 (lux) for the elderly, it is important to note that the measurement gives us a<br />
number below this value. This result gives justification to change the lighting to classify it as only<br />
good with an 8 on a scale of 5-10. The questioning in July, is related to the temperature of the<br />
room, if it is deemed for the good performance of pupils and teachers, cataloged them both in<br />
Kindergarten and Primary School under 8, or Regular. Here we see the data in the study of<br />
“Verification of environmental conditions in the facility design of the buildings at the preschool level<br />
ups in the education sector in Hermosillo, Sonora”.<br />
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Table 2. Results obtained in the ergonomic study research “Verification of environmental conditions<br />
in the facility design of the buildings at the preschool level ups in the education sector in Hermosillo,<br />
Sonora” in Kindergarten “Los Arroyos”.<br />
The INIFED says that the environmental conditions that are suitable for work in comfort in the<br />
case of classrooms are 18 to 25 degrees Celsius and can see that this condition is not met, most<br />
of the measurements exceeds 25 degrees Celsius. Therefore, find out why the temperature is<br />
listed as fair, although the results reflected rather as bad. As for the results of the investigation<br />
"Anthropometry and verification of plant design of the buildings at the preschool level ups in the<br />
education sector in Hermosillo, Sonora" was against a comparative study and survey of the results<br />
were similar furnishings and facilities and equipment not designed for the good performance of<br />
students mainly, not based on anthropometric tables according to your needs.<br />
Thus, these results will support this project to strengthen Sonora School, offer these areas of<br />
opportunity for improvement in those who develop, ie, the Sonora Institute of Educational<br />
Infrastructure and also propose a concurrent engineering work, where without participation of all<br />
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stakeholders, including of course, users who guarantee from a macro perspective, the success of<br />
our project.<br />
REFERENCES<br />
1. Cavassa Cesar Ramirez, Ergonomics and Productivity (2006), Cesar Ramirez Cavassa. - 2nd.<br />
Ed - Mexico: Limusa, Chapter 8 Ergonomics and working environment.<br />
2. Evan Lindsay (2000), Management and Quality Control, Ed Thompson 2000.<br />
3. Evaluación.pdf<br />
http://www.inifed.gob.mx/NORMASTÉCNICAS/VOLUMENTomo20PlaneaciónProgramaci<br />
óny<br />
4. Francis Quintero (2010) "Verification of environmental conditions in the facility design of the<br />
buildings at the preschool level ups in the education sector in Hermosillo, Sonora."<br />
5. Hiram Higuera (2010) Anthropometry and verification of plant design of the buildings at the<br />
preschool level ups in the education sector in Hermosillo, Sonora. "<br />
6. Julius Panero (1993), The human dimensions indoors, Ed G. Gili, SA., Mexico, D.F., pp. 23.<br />
7. C. S. Lim and M. Mohamed Zain (1999) "Criteria of project success: an Exploratory re-<br />
examination", International Journal of Project Management Vol 17, No. 4, Great Britain,<br />
pp. 243-248.<br />
8. O terminal, David J. (1990), Ergonomics in action: adaptation in the working environment of<br />
man. - 2nd edition - Mexico: Trillas, (reprint 2007).<br />
9. Roberto Hernandez Sampieri (1998) Research Methodology, Ed McGraw-Hill.<br />
10. Standardization of the STPS, www.stps.gob.mx<br />
11. Ted Klastorin (2008) Project management. Alfaomega Group Editor. Mexico City, Mexico. 242<br />
pages.<br />
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<strong>DE</strong>SIGN AND IMPLEMENTATION OF MANUFACTURING CELL<br />
WITH ERGONOMIC SUPPORT ANALYSIS<br />
MC. Rigoberto Zamora Alarcón 1 , Ing. Manuel Enrique Alcaráz Ayala 2 ,<br />
MC. Julio César Romero González 3<br />
1 Ingenieria Mecánica-Industrial<br />
Universidad Autónoma de Baja California-Instituto Tecnológico de Mexicali<br />
Blvd. Benito Juárez S/N<br />
Mexicali, Baja California 21100<br />
mczamora02@yahoo.com.mx<br />
2 Ingeniero de Manufactura ambiental<br />
Consultor Independiente<br />
Mexicali, Baja California<br />
enrique.alcaraz@hotmail.com<br />
3 Ingeniero de manufactura y proyectos<br />
Instituto Tecnológico de Mexicali<br />
Mexicali, Baja California<br />
mc.julio.romero@gmail.com<br />
Resumen: Este estudio muestra el desarrollo del proyecto desde la perspectiva general del<br />
análisis de riesgo ergonómico utilizando el método RULA (Rapid Upper Limb Assessment). El<br />
análisis arrojo información para mejorar el ambiente de trabajo. Se desarrollo el Proyecto de<br />
evaluación ergonómica en una compañía metalmecánica con más de 16 años en Mexicali, con el<br />
propósito de enfocar esfuerzos en la prevención de riesgos ergonómicos.<br />
El proyecto se apoyo en las características retrospectivas (5 años) de los registros médicos,<br />
evidenciando lesiones músculo tendinosas en muñecas en las áreas de trabajo de ensamble,<br />
específicamente en una estación en particular; los cuales fueron determinantes para definir el<br />
proyecto en las celdas de manufactura.<br />
Objetivo: Reconocer evaluar y controlar los riesgos laborales por actividades repetitivas,<br />
posturas, y agentes del medio que por sus características puedan causar daños a la salud,<br />
considerado el análisis ergonómico aplicado al concepto de celdas de manufactura<br />
Metodología empleada: Normas oficiales Mexicanas de STPS (Secretaria de Trabajo y<br />
Previsión Social) vigentes, Evaluación RULA/BRIEF, Mediciones antropométricas, Principios de<br />
celdas de manufactura<br />
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Resultados<br />
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Tabla 1 Resultados del proyecto<br />
Mejora en Índice de frecuencia<br />
Tendinitis 95%<br />
Dolor de cuello 100%<br />
Espalda 90%<br />
Beneficio<br />
Rotación de personal 0%<br />
Desperdicio -33%<br />
Optimización de espacio 40%<br />
Productividad 40%<br />
Condiciones ambientales<br />
Iluminación 100%<br />
Ruido 100%<br />
Conclusiones: Con base a los datos obtenidos:<br />
Disminuyo el índice de frecuencia de lesiones por tendinitis, dolor de cuello y espalda;<br />
impactando de manera favorable la rotación<br />
Se considerarán para el diseño de las estaciones de trabajo, la media poblacional del estudio<br />
antropométrico<br />
Se comprobó que el costo beneficio de la aplicación de la ergonomía generó mejoras<br />
significativas en las condiciones laborales beneficiando a casi 500 empleados<br />
Palabras Clave: Celdas de manufactura, RULA, Análisis Ergonómico<br />
Abstract: This study shows the project's general perspective for ergonomic hazards using the<br />
RULA’s (Rapid Upper Limb Assessment) method. Analysis shows information to improve the work<br />
environment. Project ergonomics was developed in a metalworking company with over 16 years in<br />
Mexicali, with the proposed of focusing efforts on preventing ergonomic risk.<br />
The project was supported in retrospective characteristics (5 year) medical records, which showed<br />
muscle lesions in wrist tendon (CTD: Cumulative Trauma Disorder) areas specifically assembly<br />
work at a particular station, were decisive in defining the project in manufacturing cell.<br />
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Objectives: Recognize asses and control the labor risks for repetitive activities, postures, and<br />
environmental agents that have certain characteristics may cause damage to health, considered<br />
the ergonomic analysis applied to the concept of manufacturing cells.<br />
Used methodology: Mexican official standards of existing STPS (Secretaria de Trabajo y<br />
Previsión Social), RULA Assessment, Anthropometric measurements and Principles of<br />
manufacturing cells.<br />
Results:<br />
Table 1 Project results<br />
Improved Frequency index<br />
Tendinitis 95%<br />
Neck pain 100%<br />
Back and shoulders 90%<br />
Benefits<br />
Absenteeism 0%<br />
Waste -33%<br />
Space optimization 40%<br />
Productivity 40%<br />
Environmental conditions<br />
Ilumination 100%<br />
Noise 100%<br />
Conclusions: Based on the data:<br />
Reduce the frequency index of tendinitis injuries, neck and back pain, favorably impacting the<br />
absenteeism.<br />
Will be considered for the design of workstations, the population mean anthropometric study.<br />
It was found that the cost benefit of the application of ergonomics to yield significant<br />
improvements in working conditions, benefiting nearly 500 employees.<br />
keywords. Manufacturing cells, RULA and Ergonomic Analysis<br />
1.- INTRODUCTION<br />
This study shows some of the environmental factors of process redesign in a metalworking<br />
company with over 16 years in Mexicali, initiating the development of the project from the overall<br />
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perspective of ergonomic risk analysis methods using RULA (Rapid Upper Limb Assessment) /<br />
BRIEF. The analysis yields information to improve the working environment, in order to focus<br />
efforts on preventing ergonomic hazards.<br />
The project will support the features retrospectives (five years) of medical records, showing<br />
muscle tendon in wrist injuries in the assembly work areas, specifically in a particular season,<br />
which were crucial in defining the project in the cells manufacturing.<br />
Later it was necessary to implement each of the principles of manufacturing cells, which had as<br />
one of its aims to cut down injuries sustained when production lines were used and the<br />
advantages that the implementation of this system of manufacturing production in its approach .<br />
It was remarkable to observe that first applied the standards and principles Japanese and<br />
Mexican Americans than the standards established by federal labor law.<br />
2.- Objective<br />
Recognize evaluate and control occupational hazards by repetitive activities, postures, and<br />
environmental agents which by its nature could cause damage to health, considered the<br />
ergonomic analysis applied to the concept of manufacturing cells<br />
3. Methodology<br />
3.1. Factors and Design Techniques<br />
To develop improvements as a project in newly created department was required to first<br />
determine the factors necessary in a process or product improvement, further weighting. Factors<br />
that were discussed and were weighted were: packaging, ergonomics, reliability, maintenance,<br />
manufacturing, environment, performance and safety. Of the above factors stood out in his group,<br />
ergonomics and manufacturing, which were diagnosed as other such systems and subsystems as<br />
corresponded in the following items on this article.<br />
3.1.1 Weight and diagnostic medical. To be able to support the weight of the plant physician, was<br />
necessary to make a diagnosis of injuries in the last 5 years behavior which is shown in Figure 1.<br />
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Figure 1. Injury graphic in the last five years in the production line<br />
As can be seen from the graph in Figure 1, tendinitis injuries were the most frequently expressed,<br />
in analyzing the documents supporting the physician receives a particular station as the main<br />
carrier of the injury. It was decided to take a more precise analysis of the case which had<br />
previously been tested ergonomically down significantly, however, the cases have involved the<br />
previous year that operators avoid working in the station. The weighting is determined whether<br />
one could know if our proposals were significant in their environment, it was necessary for the<br />
same thermal analysis on a ship operated blade in a municipality that maintains extreme<br />
temperatures in the year. Realising the study as shown in Figure 2, the tendinitis was found<br />
increased in the months where the heat is great in Mexicali.<br />
Figure 2. Tendinitis injury in the last five years<br />
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3.2. Mexican Official Standards of STPS (Secretary of Labor and Social Welfare) in force Federal<br />
Labor Law art. 132 Obligations of Employers Cap. X, Ergonomics art. 102. (Federal Regulation on<br />
Safety, Hygiene and Working Environment 1997)<br />
The official Mexican standards determined by the Secretary of Labor and Social Welfare in effect<br />
allowed us to measure each of the parameters set by physical and chemical conditions, however,<br />
to labor issues in the area we focus on the chemical physics but also evaluated<br />
3.2.1 Physical<br />
Vibrations (NOM-024-STPS-2001),<br />
Noise (NOM-011 - STPS-2001). Concentration equivalent dB (A): continuous, intermittent,<br />
fluctuating and Impact,<br />
Lighting (NOM-025-STPS-1999)<br />
a) Disposition: General, located, and auxiliary<br />
b) Artificial: Incandescent, fluorescent, vapor and H<br />
c) Natural<br />
d) Combined<br />
Radiation<br />
a) Ionizing (NOM-012-STPS-1999) x-rays, radioisotope and other<br />
b) Non-ionizing (NOM-013-STPS-1993), ultraviolet, infrared, radio frequency and other static<br />
Electricity (NOM-022-STPS-1999)<br />
Thermal conditions (NOM-015-STPS-2001)<br />
3.2.2 Chemicals<br />
Substance (NOM-010 - 1999 STPS-)<br />
3.3. Anthropometric measurements<br />
Some anthropometric measurements of operators are working in the plant are shown in Table 1<br />
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Table 1 Some anthropometric measurements of line operators<br />
3.4. RULA Assessment / BRIEF<br />
Poor posture is considered one that moves away from a neutral position or physiological, where<br />
they play an important role while maintaining the posture and the handling of heavy objects.<br />
(Kroemer 2000). Since the results were assessed at the station representing more problems in<br />
production lines using the method as the main tool right RULA showed results that could be<br />
considered in the design of new stations. First results were deciphered on the right of operators to<br />
both women and men as shown in Figure 3 where we obtained the results of urgent change of<br />
season.<br />
3.5 Principles of manufacturing cells (Villaseñor 2009)<br />
1. Place machines and workstations as close as possible to minimize the distance to be walking<br />
2. Free from obstructions routes and install comfortable floor worker<br />
Increase the safety of workers<br />
Improved productivity<br />
Greater flexibility of work for each operator<br />
2. Keep the cell width of 4 feet to allow flexibility, relocation and redistribution of work among team<br />
members<br />
Minimize distances of each operator<br />
Operators have access to both sides of the cell<br />
Increases the flexibility of the work cycle, so there may be operating on both sides of the<br />
cell U<br />
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Figure 3. RULA Evaluation for production line (belt)<br />
4. Heights consistently maintain places of work and materials at the point of use<br />
5. Locate the end of the line as close as possible to the next line.<br />
6. Avoid carrying a piece of top-down and front-back<br />
Always avoid placing the parts manufactured in shelves, racks, boxes or any container that is<br />
out of the process<br />
7. Where possible, use gravity to assist the operator in the placement and movement of materials<br />
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8. Design a system of two containers refill<br />
9. Install flexible and movable equipment in the cell distribution to fit easily<br />
Facilitates continuous improvement efforts, reduce time and costs for the relocation of<br />
production in cells<br />
Improve response times to changes in products or processes<br />
8. Manufacturing cell design for flexibility of volume<br />
a. Flexibility:<br />
b. Design assembly line layout to cellular manufacturing in a "U" or "U" open.<br />
c. Eliminate communication barriers and increase teamwork<br />
9. Minimize the distance between operations transfer<br />
10. Cycle times operator must be at or below the target time / takt<br />
a. Ensure that the cell meets the customer demand time<br />
b. Ensures that meets the capacity requirements<br />
13. Design routes operating within the cell, making sure not cross<br />
a. Increases operator safety<br />
b. Facilitates flow of material<br />
c. Optimize productivity by removing obstacles from the path<br />
d. Ensures follow-up sequence of work<br />
14. Design the cells for operators to work within it.<br />
a. Promotes communication and teamwork<br />
b. Improved response time and operating in several machines or workstations<br />
c. Optimize production space<br />
d. Reduce travel distances<br />
15. Design the cells so that the rotation of the work is against clockwise<br />
a. Improved ergonomic design<br />
b. Facilitates milestone<br />
c. Standardize more material flow<br />
d. Eliminate wasted movement when moving the product of the hand that receives the<br />
working<br />
16. Design the cells so that the operations are more than one piece among stations<br />
a. Minimize WIP<br />
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b. Pull Production System or milestone<br />
17. Design the cells to ensure that all parties go through all seasons<br />
18. Design the cells so that the operator can easily perform various operations.<br />
a. Helps to improve the ergonomic design by reducing repetitive movements<br />
b. Improves mobility and versatility of workers<br />
c. Allows greater flexibility<br />
d. Promotes "system thinking", continuous improvement<br />
e. Eliminate each operation specialists<br />
f. Improved response time<br />
g. Improved communication<br />
h. Improved teamwork<br />
i. Improving the skills of each to rotate the cell operations<br />
19. Design the cells so that the operator never trapped<br />
20. Better handling of material<br />
a. Improving the response time<br />
4. Results<br />
4.1 Medical conditions for improved stations applied in manufacturing cells<br />
Measurements after the improvements implemented in the stations of the manufacturing cells<br />
reduce injuries allowed as shown in Figure 4<br />
4.2. RULA assessment implemented in manufacturing cells. Improvements in manufacturing<br />
cell stations were significant as shown below. First results on the right of operators to both<br />
women and men shown in Figure 8 and Figure 9 where we obtained the results to changes in<br />
tasks<br />
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Figure 4 raph of injuries sustained in the first year of cells<br />
5. Conclusions:<br />
6.<br />
1. We complied with the standards prescribed by the current Mexican<br />
2. Engineering controls were implemented through:<br />
a) were improved work areas with more light,<br />
b) decreased redesign of machinery noise<br />
c) the use of workstations in the corresponding cells that fulfilled the relevant principles<br />
d) Development of tools to reduce ergonomic hazards<br />
e) Improved handling containers and material moving<br />
3. Administrative Controls<br />
• Work was rescheduled through the seasons in the manufacturing cell<br />
• were established relaxation breaks that allow staff<br />
4. Work practice controls<br />
• is looking to keep the body in neutral positions<br />
5. Based on the data obtained from the RULA ergonomic evaluation and implementation of<br />
manufacturing cells<br />
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Figure 5 RULA evaluation in cell<br />
a. Reduce the frequency rate of tendinitis injuries, neck and back pain, impacting favorably<br />
rotation<br />
b. be considered for the design of workstations, the population mean anthropometric study<br />
c. It was found that the cost benefit of the application of ergonomics led to significant<br />
improvements in working conditions, benefiting nearly 500 employees<br />
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5. REFERENCES<br />
Kromer, Grand Jean E (2000) Fitting the task to the human. Taylor & Francis<br />
Villaseñor, Contreras Alberto (2009) Lean Manufacturing ed. Limusa Mexico, D.F.<br />
Ley Federeal del Trabajo y Leyes de Seguridad Social 2009 Tax Editores unidos, S.A de<br />
C.V. Mexico, D.F.<br />
Zandin, Manual del Ingeniero Industrial quinta edición, ed. McGraw-Hill<br />
Niebel/Frievalds (2006) Ingenieria Industrial, Métodos, Estándares y Diseño del Trabajo,<br />
11ª Edición. (ed. Alfaomega)<br />
Mondelo, Pedro R, Gregori, Enrique, Blasco, Joan, Barran, Pedro (2004) Ergonomía 3<br />
Diseño de puestos de Trabajo, Ed. Alfaomega<br />
Baudin, Michel (2001), Design of Manufacturing Cells.<br />
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