• 대한인간공학회지
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• 제23권4호
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• pp.35-43
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• 2004

The purpose of this study is to redesign a letter sorting station and to present the optimal work-space through the ergonomic analysis of the sorting station for reducing the 'Work-Related MusculoSkeletal Disorders(WMSDs)'. We surveyed the work environment in terms of the reason causing WMSDs. According to the survey results, Deltoid on the arm, Trapezius on the shoulder and Erector Spinae on the waist are most frequent attacking parts. Accordingly, We classified sorting stations by the horizontal work-space(Level 1, Level 2, Level 3) and the vertical work space(Level 1, Level 2) based on the criteria of ergonomic optimal work-space. In addition we improved the sorting station through investigation and analysis of the work-load regard the each defined work-space. In order to analyze the effect of the horizontal and vertical work-space, subjects carried out simulated sorting tasks. Each level(Level 1, Level 2, Level3) of the horizontal work-space is significant regarding each muscles(the shoulder, arm and waist), and each level(Level 1, Level 2) of the vertical work-space is significant regarding the arm and waist, but not shoulder. Finally, we founded the difference of work-load according to the work-spaces. Then, it is necessary to improve the work-space causing the high work-load(Level 3 of the horizontal work-space). Then, this study presented the specification of a sorting station which is suitable to the korean body size, and constructed the 3D shaped model of the stations by the ergonomic analysis.

• 대한안전경영과학회지
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• 제13권2호
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• pp.83-90
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• 2011

It has been very important to have an exact evaluation for risk factors in order to prevent WMSDs(Work-related Musculoskeletal Disorders). However, most WMSDs evaluation methods have always been some problems of possibilities associated with subjective evaluation. Therefore, this study tried to conduct a sort of usability analysis on three major evaluation methods(OWAS, RULA, REBA). Specifically, major subjects in the study consisted of three parts as follows; comparison of the results between experienced and inexperienced observers, analysis for the consistency of the results in terms of different evaluation times, and analysis for the consistency of the results in terms of different job characteristics(based on the part of the automobile). The results of the study were summarized as follows; 1) There was statistically significant difference of the results by RULA and by REBA between experienced and inexperienced observers. This might be due to the fact that experienced observers have had better ability to detect the important working posture during evaluation. However, the results by OWAS did not give any significantly different results between experienced and inexperienced observers, 2) All three checklists applied by experienced subjects did not show any single result significantly different in terms of different evaluation times. This might have to do with high intra-observer reliability from some of previous studies, 3) The five parts of an automobile were selected as five major jobs with different job characteristics in the automobile industry. Specifically, they were door part, front part(hood, etc.), inside part(dash board, seats, etc.), rear part(trunk etc.), and bottom part. All three methods did not show any significant differences for the results from each observers. Further study on this subject would eventually provide a sophisticated evaluating guidelines for WMSDs regarding determination of observer-specific evaluation, identification of repetitive number of evaluations for stable results for each checklist, determination of job-specific evaluation methods, and so on.

• 한국안전학회지
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• 제24권4호
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• pp.90-95
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• 2009

The purpose of this study is to investigate industrial safety and health experts' opinions on the examination system of WMSDs(work related musculoskeletal disorders) risk factors. For doing this, a questionnaire study and two FGIs(focused group interview) were conducted. A questionnaire with open questions about the examination system was developed, and sent to 42 experts consented bye-mail. Of the experts, 24 experts responded, whose data were used in the analysis. The FGIs were performed for the persons in charge of industrial safety and health in industries and ergonomists. The questionnaire study revealed that most experts(91.3%) agreed with legalization of employers' duty for preventing WMSDs, necessity of the 11 tasks designated by Ministry of Labor, the examination system and ergonomics program, and pertinency for the examination system classification of periodic and occasional one. However, more than half experts disagreed with timeliness and appropriateness of the legal system. This was validated by the low approval rates for appropriateness of the 11 tasks, methods of the examination, charge person in the examination and ergonomics program. FGIs showed that it was desirable for the examination system to be legalized, and that the system was generally properly performed. It was suggested that the system be partially revised with reflecting problems disclosed during its enforcement rather than whole revision. It is expected that when revising relevant legal system, the results of this study would be used as valuable data.

• 대한인간공학회지
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• 제31권1호
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• pp.165-170
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• 2012

Objective: The aim of this study is to develop new K-OWAS on the basis of the anthropometry of Koreans considering works in shipbuilding and heavy industry for evaluation whole-body working postures. Background: Work Related Musculoskeletal Disorders(WMSDs) were a leading cause of sick leaves and injuries in the industries of our country. Especially, awkward working postures and handling of heavy weight are known as a main cause of WMSDs. OWAS, RULA and REBA are much used as the method for evaluating the awkward working postures. OWAS is the working postures evaluation method that can be used for the evaluation of whole-body working postures. OWAS was the method made based on the anthropometry of the foreigner, working postures and weight does not fit our work state. Method: This method was evaluated considering the anthropometry of the Koreans, working postures and weight in shipbuilding and heavy industry work state in Korea. Results: Correlation of action level of OWAS and subjective discomfort for each body parts were not statistically significant($p{\geq}0.1$). But correlation of action level of K-OWAS and subjective discomfort for torso and waist were statistically significant($p{\leq}0.1$). Conclusion: K-OWAS was suitable in the evaluation of upper body including torso and waist. Application: New method for whole-body working postures from this study prevent WMSDs and help improvement of working environment and design of working method.

• 대한인간공학회지
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• 제24권2호
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• pp.57-63
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• 2005

Ergonomic intervention techniques were adopted to assess and control potential risk factors of work-related musculoskeletal disorders(WMSDs) in the automated light assembly manufacturing system. Ten different kinds of assembly workstations implemented with a conveyor system and twelve female workers were observed and evaluated with careful video film analysis. Several close examinations using sets of checklists established by qualified safety and health organizations, such as NIOSH, OSHA, and ANSI, were conducted and every workers and staffs in the site participated in the self-report questionnaires and off-line interviews. Typical risk factors and symptoms of the upper extremity musculoskeletal disorders were found and categorized into specific parts of body. To reduce risk factors of WMSDs and improve system productivity new revised workstation standards, physical dimensions, were suggested accordant with anthropometric characteristics of workers and a heuristic decision strategy of rotating shift work schedules according to work contents has proposed to mitigate cumulative physical stress. Finally, ergonomic programs of entire company to prevent WMSDs were structured.

• 대한인간공학회지
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• 제32권2호
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• pp.199-205
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• 2013

Objective: The aim of this study is to investigate the job rotation implementation at medium- or small-industries and to identify the viewpoint on job rotation as preventive activity of work-related musculoskeletal disorders(WMSDs). Background: Job rotation has been implemented in many industrial areas in order to prevent the WMSDs as one part of ergonomic program. Generally, the cases of implementation of ergonomic program or successful cases of job rotation were reported on the side of major or large company. Therefore, this study tried to inspect the current state of job rotation implementation at medium- or small-industries. Method: Survey was carried out for randomly contacted forty seven mangers responsible for safety. Survey contained the questionnaires on the general state of company, shift-work and job rotation. Results: The ratio of work-shift in medium- and small-industry was 34.0% and the ratio of job rotation was 19.1%. For manufacturing industry, the ratio was 37.9% and 17.2%, respectively. Conclusion: The implementation ratio of job rotation was relatively low considering the results of previous studies. Many managers appealed the quality decreasing of goods and the injuries of workers due to job rotation, though agreed to train the multi-functional worker and to prevent the WMSDs. Application: The results can be used for the fundamental data how the job rotation will be properly implemented in medium- and small-industry as an administrative control for MSDs.

• 대한산업공학회지
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• 제28권2호
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• pp.223-231
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• 2002

Recently, work-related musculoskeletal disorders(WMSDs) have rapidly increased and have been a major issue in the field of industrial safety. Of several physical risk factors for WMSDs, which include postures, vibration, repetitive work, speed or acceleration of movements, etc., awkward postures have been known as one of the major causes of WMSDs. For reducing the potential for injury as a result of postures, cost effective quantification of the magnitude for physical exposure to poor working postures is important and needed. To do this, several postural classification schemes have been developed and used in industrial sites. It is known that perceived discomfort for joint motions and muscle strength for females were much less than those for males. However, the existing postural classification schemes were developed without considering these gender effects. This study aims to develop a new postural classification scheme for female workers, based on the perceived discomfort for joint motions. The result showed that there was significant difference between the schemes for female and male. It was also found that when compared with OWAS, RULA and REBA, postural load was quantified more precisely with the developed scheme. It is recommended that different schemes according to gender of workers involved in work be used in order to accurately evaluate postural load of work postures.

• 한국안전학회지
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• 제21권4호
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• pp.114-118
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• 2006

Recently, work-related musculoskeletal disorders(WMSDs) is one of the major issues in the shipbuilding industry. The number of injured workers has rapidly increased and demands for workers compensation, improvement of work condition and environment to prevent WMSDs become larger. To protect and reduce WMSDs in the shipbuilding industry, simulation technique which showed it's ability of increasing the manufacturing productivity will be applied, because simulation technique has the evaluation ability for a worker's danger level of production process by human activity analysis. In our research, we modeled worker's attitude and simulated worker's action. We evaluated the caution level, compared and analyzed the difference point of digital human which made on computer and actual worker's attitude to check feasibility of human modeling and simulation in the shipbuilding industry.

• 대한인간공학회지
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• 제29권4호
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• pp.487-493
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• 2010

Work related musculoskeletal disorders (WMSDs) became a major problem since 2000 in shipbuilding industry. WMSDs are known to be resulted from awkward postures, high repetitive motions, excessive forces, mechanical stress and vibration. Korean government enacted a law to require companies to take measures to prevent musculoskeletal disorders at work. If there are more than 10 incidences of WMSDs or 5 incidences which are more than 10 percent of all workers in a company, this law requires a company to implement an ergonomics program. A few large companies in shipbuilding industry have already implemented or are in the process of implementing an ergonomics program. This paper presents a case study of an implementation of an ergonomics program in a Korean shipbuilding company. We audited the process of the ergonomics program in this shipbuilding company four times for 3 years. Based on the findings, this paper presents effects and problems of an ergonomics program and improvement measures of them. These findings will help companies which want to implement an ergonomics program in the future.

• 대한인간공학회지
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• 제28권3호
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• pp.81-85
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• 2009

Work related musculoskeletal disorders(WMSDs) was a leading cause of sick leave and injuries in the industries of our country. Posture was an important consideration in the design of work method and workplaces, because it affected the ability of workers to use various equipments and influenced how long they could perform their job without feeling discomfort, fatigue, and musculoskeletal disorders. Imbalanced lower limb postures such as a squatting posture were awkward working postures common to the shipbuilding shops, farms, automobiles assembly lines in our country. Different awkward working postures were known to be associated with specific musculoskeletal disorders. Eight postures in lower limb postures divided into balanced and imbalanced postures were evaluated by electromyographic(EMG) activity for lower limb muscles. Twelve male subjects participated in this study. This paper was to analyze the effects of lower limb muscles workload according to lower limb postures(knee angle) and working time. The ANOVA results showed that most EMG root mean square(RMS) values were statistically significant effect according to lower limb postures(knee angle) and working time. Therefore, the results of this study will provide the basis to evaluate workload of lower limb postures correctly adopted by workers in various jobs and the ergonomic reference to prevent WMSDs.