• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.209-213
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• 1997

Manual lifting techniques are commonly defined in terms of the postures adopted at the start of the lift. Quantitative definition is problematic, however, because the absolute joint angles adopted to lift an object are influenced by task parameters, such as the initial height of the load. The main objective of this study is to investigate the grip strength of the both hands at the initial lifting points. The survey is conducted by measuring the compression force, anthropometric data and grip strength at the lifting postures for the subjects(n=50) who is assigned to their job as usual. The experiment is peformed at the four lifting postures which involving the combination of two horizontal factors(H1 : 35 cm, H2 : 55 cm) and two vertical factors(V1 : 20~80 cm, V2 : 47~102 cm). The analysis result of lifting posture indicated that each H1-V1, H2-V1 combinations are about 60$^{\circ}$ and each H1-V2, H2-V2 combinations are about $30^{\circ}$. There are significant differences on grip strength between $60^{\circ}$ and $30^{\circ}$ stooped posture. The results of this study can be provided a method defining lifting postures at the minimum grip strength. Also, it is eliminated a hazard of the injuries which are cumulative trauma disorders(CTDs) and back pain, increased a productivity and improved a welfare of workers.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.4
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• pp.459-465
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• 1999

A new-concept VDT workstation chair with adjustable keyboard/mouse support was proposed to minimize physical discomfort and the risk of cumulative trauma disorders (CTDs) at work sites in this study. First, a three-dimensional human modeling tool $(SAFEWORK^{(R)})$ was used to design the new chair satisfying the anthropometric specifications of Korean population. Second, based upon the result of 3-D graphical simulation, a mock-up chair was constructed with an adjustable keyboard/mouse support directly attached to the chair body. Third, muscle fatigue and subjective discomfort were measured to evaluate the newly developed chair. An experiment was conducted to compare the new workstation chair to the traditional computer chair without keyboard/mouse support. Six volunteer subjects participated in six one-hour word-processing sessions with two different chairs and three different postures. Statistical results indicate that the new-concept VDT chair generally improved subjective comfort level and reduced fatigue in finger flexor/extensor and low back muscle. In conclusion, this new VDT workstation chair is expected to reduce physical discomfort and prevent occupational CTD problems in the long run. Implications of the new design and suggestions for the further development are also addressed.

• Proceedings of the Safety Management and Science Conference
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• 2002.05a
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• pp.199-205
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• 2002

최근 산업안전/보건분야에서 누적외상성질환(Cumulative Trauma Disorders： CTDs)과 직업성요통(Low Back Injury)과 같은 근골격계질환은 산업현장에서 어렵지 않게 발견할 수 있는 신종 산업재해의 일종이다. 특히 미국의 경우, 발생건수와 그로 인한 인적/물적 손실이 급격하게 증가되고 있는 것으로 나타나고 있다. 그러나 미국과 같이 근골격계질환의 폐해를 일찌감치 인식하고 그 해결방안을 연구해온 나라들에서는 현재 환자관리 및 인간공학적인 기준 등을 포함하는 예방지침들이 잘 정착되어 있는 실정이다. 우리나라의 경우에는 작업환경 등의 조건과 상황이 미국과 같은 구미 선전국과 비숫하고, 특히 제조업의 생산체계가 그런 나라들과 매우 유사하여 근골격계질환의 발생과 그로 인한 인적/물적 손실이 적지 않을 것이라고 예상할 수 있지만 아직까지 CTDs에 대한 전반적인 이해가 부족하고, 정확한 실태가 파악되지 못하였으며, 따라서 체계적인 관리 대책 또한 마련되어있지 않은 실정이다. 본 조사에서는 서울 근교의 수송기계관련 사업장의 작업들에 대한 작업자세에 중심을 둔 인간공학평가를 통하여 조사 작업의 근골격계질환에 대한 상대적인 위험도, 위험요인 등을 파악하고, 그에 따른 개선 대책의 방향을 제시하고자 하였다. 특히, 각 부위별 위험점수와 부위별 증상호소율의 상환분석결과, 작업자 개인적 수준에서는 통계적으로 유의한 차는 없는 것으로 분석되었으나, 부서별로 분석한 결과, 작업시 주로 사용하는 오른쪽 상지의 경우, 오른쪽 어깨, 팔꿈치, 손목 순으로 통계적으로 유의하게 관련이 있는 것으로 나타났다. 즉 증상호소율과 해당 신체부위의 위험도 점수는 서로 정적(positive)한 관계에 있는 것으로 나타났고, 상지 중 주로 사용하는 오른쪽 부담의 위험도 자세 점수와 증상호소는 비교적 높은 상관관계에 있는 것으로 나타났다. 따라서 이와 같은 인간공학적 분석결과는 향후 인간공학적인 개선대책의 개발 뿐만 아니라 의학쪽에서 근골격계질환을 접근하는 초기단계에서 매우 유용한 역할을 할 수 있으리라 생각된다.

• Journal of the Ergonomics Society of Korea
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• v.36 no.3
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• pp.183-196
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• 2017

Objective: The purpose of this research was to assess the agreement between job physical risk factor analysis by ergonomists using ergonomic methods and physical examinations made by occupational physicians on the presence of musculoskeletal disorders of the upper extremities. Background: Ergonomics is the systematic application of principles concerned with the design of devices and working conditions for enhancing human capabilities and optimizing working and living conditions. Proper ergonomic design is necessary to prevent injuries and physical and emotional stress. The major types of ergonomic injuries and incidents are cumulative trauma disorders (CTDs), acute strains, sprains, and system failures. Minimization of use of excessive force and awkward postures can help to prevent such injuries Method: Initial data were collected as part of a larger study by the University of Utah Ergonomics and Safety program field data collection teams and medical data collection teams from the Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Subjects included 173 male and female workers, 83 at Beehive Clothing (a clothing plant), 74 at Autoliv (a plant making air bags for vehicles), and 16 at Deseret Meat (a meat-processing plant). Posture and effort levels were analyzed using a software program developed at the University of Utah (Utah Ergonomic Analysis Tool). The Ergonomic Epicondylitis Model (EEM) was developed to assess the risk of epicondylitis from observable job physical factors. The model considers five job risk factors: (1) intensity of exertion, (2) forearm rotation, (3) wrist posture, (4) elbow compression, and (5) speed of work. Qualitative ratings of these physical factors were determined during video analysis. Personal variables were also investigated to study their relationship with epicondylitis. Logistic regression models were used to determine the association between risk factors and symptoms of epicondyle pain. Results: Results of this study indicate that gender, smoking status, and BMI do have an effect on the risk of epicondylitis but there is not a statistically significant relationship between EEM and epicondylitis. Conclusion: This research studied the relationship between an Ergonomic Epicondylitis Model (EEM) and the occurrence of epicondylitis. The model was not predictive for epicondylitis. However, it is clear that epicondylitis was associated with some individual risk factors such as smoking status, gender, and BMI. Based on the results, future research may discover risk factors that seem to increase the risk of epicondylitis. Application: Although this research used a combination of questionnaire, ergonomic job analysis, and medical job analysis to specifically verify risk factors related to epicondylitis, there are limitations. This research did not have a very large sample size because only 173 subjects were available for this study. Also, it was conducted in only 3 facilities, a plant making air bags for vehicles, a meat-processing plant, and a clothing plant in Utah. If working conditions in other kinds of facilities are considered, results may improve. Therefore, future research should perform analysis with additional subjects in different kinds of facilities. Repetition and duration of a task were not considered as risk factors in this research. These two factors could be associated with epicondylitis so it could be important to include these factors in future research. Psychosocial data and workplace conditions (e.g., low temperature) were also noted during data collection, and could be used to further study the prevalence of epicondylitis. Univariate analysis methods could be used for each variable of EEM. This research was performed using multivariate analysis. Therefore, it was difficult to recognize the different effect of each variable. Basically, the difference between univariate and multivariate analysis is that univariate analysis deals with one predictor variable at a time, whereas multivariate analysis deals with multiple predictor variables combined in a predetermined manner. The univariate analysis could show how each variable is associated with epicondyle pain. This may allow more appropriate weighting factors to be determined and therefore improve the performance of the EEM.