• 대한인간공학회지
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• 제30권6호
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• pp.695-703
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• 2011

Objective: This study was to investigate the effects of coordinated upper-limb body postures on the subjective discomfort rating, heart rate, and muscle activities. Background: Although generally many checklists such as OWAS, RULA, and REBA were applied to evaluate various body postures, the body postures were might be overestimated or underestimated because each body part(i.e., back, shoulder, and elbow etc.) was evaluated separately, and then added all rates of individual body parts to assess an overall risk level for the body posture in these methodologies. Methods: A total of 20 participants maintained 14 postures which were combinations of back, shoulder, and elbow flexion angles and then muscle activities, subjective discomfort, and heart rates were collected every three minute during a sustained 15 minute and 0.5kg weight holding task. Four muscle groups were investigated: erector spine, anterior deltoid, upper trapezius, triceps brachii. Results: Results showed that subjective discomfort was the lowest when the angle of back and shoulder were both $0^{\circ}s$, while the body posture with $45^{\circ}$ of back angle and $45^{\circ}$ shoulder angle was rated as the most subjective discomfort posture. In general, the subjective discomfort ratings increased as back and shoulder flexion angles increased. It was noted that, however, the subjective discomfort of body posture with a $45^{\circ}$ back angle and $45^{\circ}$ shoulder flexion angle was lower than that of body posture with a $0^{\circ}$ back and $45^{\circ}$ shoulder flexion angle. The research findings of heart rates and muscle activities showed similar results for the analyses of subjective discomfort ratings. Conclusions: The possible limitations of the current ergonomics evaluation techniques which assessing a body posture with summing all body part score after individually analyzed in this study. Based on the analyses of subjective discomfort, heart rate, and muscle activities, it was recommended that a use of effects of coordinated upper-limb body postures would be considered when one evaluates work-load for various working postures. Application: These findings can be used for developing a more accurate assessment checklist for working posture as well as preventing musculoskeletal disorders of workers in workplaces.

• 한국융합학회논문지
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• 제10권3호
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• pp.67-72
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• 2019

본 연구는 일주일 동안의 컴퓨터 사용시간이 몸통 근육 두께와 압력 통증 역치에 미치는 영향을 분석하였다. 33명의 대상자를 일주일에 컴퓨터를 10시간 이하(A 그룹), 10시간에서 20시간(B 그룹), 20시간 이상 사용하는 그룹(C 그룹)으로 나누어 위 등세모근, 작은가슴근, 앞 목갈비근, 중간 목갈비근의 근 두께와 위 등세모근, 작은가슴근, 앞 목갈비근, 중간 목갈비근, 어깨올림근의 압력 통증 역치를 측정하였다. 본 연구의 결과 C 그룹의 작은가슴근, 앞 목갈비근, 중간 목갈비근은 다른 그룹들의 근 두께에 비해 유의하게 증가되었고(p<.05) 위 등세모근, 앞 목갈비근, 작은가슴근, 어깨올림근의 압력통증역치는 다른 그룹들에 비해 유의하게 감소하였다(p<.05). 그러므로, 본 연구는 1주일 동안 컴퓨터를 장시간 사용하는 사람들은 장시간 컴퓨터 사용이 다양한 근골격계 질환의 원인이 될 수 있음을 인지하고 그에 따른 적절한 예방적 접근을 수행할 것을 권장한다.