Iranian Journal of Ergonomics
Year:2018 | Volume:5 | Issue:4 |Papers Count:10

Background: The design and manufacturing process in electronic companies is the most time consuming work behind computers. Because of the high prevalence of musculoskeletal disorders in computer users, researchers need to identify risk factors and ergonomic problems and ways to reduce them.Methods: This study was a descriptive-analytical study and was conducted as an intervention in Behpajooh engineering company in Isfahan. Statistical sampling was done by global sampling (31 people). The Nordic questionnaire and the Rapid Office Strain Assessment (ROSA) were used to evaluate the risk factors of ergonomics. Data analysis was performed by using McNemar and Wilcoxon's non-parametric tests and using SPSS software.Results: The results of the Nordic questionnaire, before ergonomic intervention, the frequency of problems in elbow is zero, in waist, upper back, neck and shoulders is 45-38%. Evaluation of Ergonomic Risk Factors derived from the Rapid Office Strain Assessment before intervention showed 35.5% (11 people) at low risk, 38.7% (12 people) in the warning zone and 25.8% (8 people) in the area requiring ergonomic intervention. Statistical analysis of ergonomic interventions showed that the number of people in the area of warning and necessity are less than the number of people before intervention.Conclusion: The most musculoskeletal disorders were reported in the neck, lower back, upper back and shoulders. Statistical results after ergonomic intervention indicate a decrease in these disorders. The results led to the understanding that the risks in electronic companies could be reduced by ergonomic interventions. Implementation of ergonomic interventions based on engineering, management and educational proceeding can be effective in reducing musculoskeletal disorders.

Background: Inadequate lighting in the workplace can cause unconventional changes in the posture of office workers. Poor ergonomic conditions in the office cause inappropriate postures during work and increase pressure on the musculoskeletal system which can cause some disorders in long-term. In this study, the relationship between work environment lighting with the prevalence and severity of musculoskeletal pain among office workers has been investigated.Methods: In this study, the intensity of local illumination at work surface and at the perpendicular surface (perpendicular surface to the work surface and at the height of workers eye), and intensity of general lighting was measured based on the standard of The Illuminating Engineering Society (IES) using the SEKONIC, C-7000 SpectroMaster. Also, to assess the prevalence and severity of pain of musculoskeletal disorders, a Nordic Questionnaire and a Body map index were used respectively. To assess the office work strain, Rapid Office Strain Assessment techniques (ROSA) were used. Data were analyzed by SPSS 21.Results: The results showed that the average intensity of general lighting, local lighting at work surface and at the perpendicular surface were 30.6%, 33.9%, and 38.4% respectively, which is lower than required illumination intensity of Occupational Exposure Limits (OEL). The neck and waist had the highest prevalence of the musculoskeletal disorders among the workers. The highest frequency percentage of scores in the ROSA method was the score 5 (41.7%) which had a significant correlation with illumination intensity.Conclusion: Illumination intensity can be considered as one of the important factors affecting posture in administrative staff. Therefore, the improvement of illumination intensity can decrease the severity of musculoskeletal pain and improve the body postures of the staff and, consequently, increase their comfort.

Background: Many workers, especially welders, have awkward postures during their working hours. Evaluating such kind of postures is done with the aim of corrective actions. Therefore, the present study was conducted to evaluate the activity of welder's muscles in common welding postures working on gas transmission pipelines.Methods: This cross-sectional descriptive-analytical study was performed on 15 welders of the Iranian Gas Transmission Co. After the required analysis, three postures that were most used working on the gas transmission pipelines were identified to evaluate muscle activity. The surface electromyography (EMG) activity of the erector spinae, biceps femoris, vastus medialis, gastrocnemius medialis, gastrocnemius lateralis, tibialis anterior, rectus abdominis, abdominal internal oblique, abdominal external oblique, and semitendinosus muscles are evaluated in three postures. They are analyzed based on the maximum voluntary contraction (MVC).Results: The results indicated that the mean of muscle activity in the kneeling posture is significantly lower than two other postures (P<0.001). The mean activity of each muscle in different postures were compared and evaluated. The highest activity was related to the tibialis anterior, vastus medialis and biceps femoris. Abdominal muscles have the lowest activity.Conclusion: The muscle activity of the welders in the evaluated postures was very high. Based on the findings of this study, the muscle activity was strongly affected by the type of posture and angle of the joints, so the muscles’ activity in the kneeling posture was lower than the two other postures due to the suitable angle of joints and the direct transmission of body weight.

Background: The purpose of this study was to identify and prioritize some factors affecting the trainers' satisfaction with the Technical and Vocational Training Organization (TVTO) by integrating of QFD and Kano models.Methods: In this study, 435 trainees aged 18 to 22 years-old from one of the highest technical and vocational education centers in Tehran were selected to complete the Kano questionnaire through direct communication with the user and interview. In this study, An integration of the Kano Model and Extend Quality Function (QFD) was used to improve the design studios of technical and professional institutions based on the needs of users ergonomically. After filling out the Kano questionnaire by the respondents, the responses were analyzed and the results were entered into the house of quality matrix (HOQ).Results: The results of the house of quality matrix (HOQ) in this study showed that the “design and safe application” factor is one of the most importantsafety features. According to users, the significance coefficient (j) is 7.35. and the significance coefficient of the furniture adjustment criterion, with the least importance, (j) is only 1.09. In addition, the thickness of materials and furniture with a definite significance of AI=52.1 had no significant relation with ergonomics and comfort.Conclusion: This results showed that both the Kano model approach and the QFD integration method can be used to identify and prioritize product design and work environment from the users' perspective.

Background: Recently adaptive neuro-fuzzy inference system is used for the classification of physical load based on three parameters including %HR max, HR rest, and body weight. The aim of this study was to optimize this model to reduce the error and increase the accuracy of the model in the classification of physical load.Methods: The heart rate and oxygen consumption of 30 healthy men were measured during a step test in the laboratory. TheVO 2max of the participants was measured directly during a maximal treadmill test. A relationship was observed between the calculated %VO2max which is considered as the gold standard of physical load and the model inputs using ANFIS in MATLAB software version 8.0.0. the genetic algorithm was then applied as an optimization technique to the model.Results: accuracy, sensitivity, and specificity of the model increased after optimization. The average of accuracy accelerated from 92.95% to 97.92%. The RMSE decreased from 5.4186 to 3.1882. Also, in %VO2max estimation, the maximum error of the mode was ±5% after optimization.Conclusion: The results of this study show that the use of Genetic Algorithm during training process can increase the accuracy and decrease the error of ANFIS model in the estimation of%VO2max.. The advantages of this model include high precision, simplicity and applicability in real-world working environments and also interpersonal differences.

Background: “Participatory ergonomics” is defined as an active participation of all members of the organization in the development and implementation of ergonomic knowledge in order to improve the working environment, quality, productivity and safety of the organization. The purpose of this study was to determine the appropriate process of working condition with the participatory ergonomic approach and its impact on one of the printing industries.Methods: This research is an interventional study carried out in one printing industry center. To identify the ergonomic risk factors the “Nordic Questionnaire" and “Ergonomic Review Points” and to evaluate the quality employees’ working life, the NIOSH modified quality of life curriculum was used. The results were by conducting a paired t-test using SPSS20 software package.Results: The investigation of health, and working conditions using the supplementary checklist before and after applying the review points with participatory ergonomic approach shows a significant increase. Data analysis using the paired t-test showed a significant improvement in quality of working life and reduction of musculoskeletal disorders after intervention (P<0.001).Conclusion: According to the results, it can be concluded that the individuals’ social skills and abilities have increased by participation in the process of participatory ergonomics. Increasing the quality of working life has a significant role to improve the health of workers and reduce occupational accidents. Therefore, the implementation of participatory ergonomic program with the collaboration of industrial managers can be an effective step towards achieving human resource satisfaction and health.

Background: The working station has a major impact on the musculoskeletal disorders, therefore a considerable attention to working station staff is of importance. The aim of this study was to investigate the effect of working station on musculoskeletal disorders among administrative staff.Methods: 30 administrative staff participated in this analytical descriptive study. Data was collected using Nordic Musculoskeletal Disorders Questionnaire (NMQ) in ergonomic design intervention of three working stations (sitting, standing-andsitting, standing) before and after of intervention. Moreover, a t-test and multiple regression were used to analyze the data.Results: The average (standard deviation) of the age and work record of 30 participating employees were 44.3 (5) and 20 (5) years, respectively. There was a significant correlation between the type of working station before and after the intervention, with the expression of musculoskeletal disorders (P=0.02). There was also a significant relationship between variables of musculoskeletal disorders in the shoulders, necks, waist and hands at different working stations. However, there was a significant relationship between age, work experience and BMI index with musculoskeletal disorders.Conclusion: According to the results of this survey the best working station is a sitting-and-standing. Therefore, by changing the type of working stations, musculoskeletal discomfort of the employees will be reduced appropriately.

Background: Problems and complications caused by inappropriate tables and chairs dimensions in changing the shape of children's body are important issues nowadays. The aim of this study was to evaluate anthropometric dimensions of the changes in elementary school students of Mazandaran province between 1992 and 2014.Methods: in two cross-sectional studies carried out between 1992 and 2014, anthropometric information of elementary school students were collected in the range of 6 to 11 years old. In 1992, 1758 students out of a population of 254204 and in 2014 2336 students out of a population of 208820 were selected using stratified random sampling method. In 1992, mechanical anthropometric was used for measuring while in 2014, an anthropometric chair photographic camera and anthropometric photogrammetric software (made by the researcher) were applied to measure. In this study, we measured the parameters of weight, amount of height, seat height, sitting height, shoulder width, hip width, thigh thickness, sitting length of the buttocks, hip length in sitting leg knee position. Data were analyzed using SPSS software package version 20.Results: Comparison of the two study revealed that the average (SD) of the boy' s weight increased from 25.82 kg (9.5) to 32.17 (11.03) (6.35 kg increase) and girls ‘weight accelerated 25.19 kg (6.5) to 33.10 (12.50) (7.91 kg increase). Theboys' height was increased from 127.26 cm (9.6) to 134.80 (10.84) (54.7 cm increase) and a raise was observed form 126.5 cm (10.1) to 133.30 (11.18) (6.8 cm) among girls’ height and there were changes in other anthropometric factors as well.Conclusion: The results show that students have significant anthropometric changes during a 22 years’ period, and it is needed to carefully design and construct children's devices especially the school chair and table.