Even though two-hands lifting/lowering activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting/lowering are also very common at the industrial site, forestry, farming, and daily life.
The objective of this study was to compare one-hand lowering activity to lifting activity in terms of biomechanical stress for the range of lowering heights from knuckle height to 10cm above floor level with two workload 7.5kg and 15.0kg. Eight male subjects with LMM were asked to perform lifting/lowering tasks using both a one-handed (left-hand and right-hand) as well as a two-handed technique. Spinal loading was estimated through an EMG-assisted free-dynamic biomechanical model.
The biomechanical stress of one-hand lowering activity was shown to be 43% lower than that of one-hand lifting activity. It was claimed that the biomechanical stress for one-hand lifting/lowering activity is almost twice (194%) of the one for two-hands lifting/lowering activity. It was also found that biomechanical stress by one-hand lowering/lifting activity with the half workload of two-hands lowering/lifting activity was greater than that of the two-hands lowering/lifting activity. Therefore, it might be a risk to consider the RWL of one-hand lowering/lifting activity to simply be a half of the RWL of two-hands lowering/lifting activity recommended by NIOSH.

1. 서 론
  1.1 연구 배경 및 목적
 2. 실험 계획 및 실험 방법
  2.1 피 실험자
  2.2 실험 장비
  2.3 실험 절차 및 방법
 3. 실험 결과 분석
  3.1 모멘트, 좌-우측 전단력, 전-후방 전단력, 압축력분석 결과
  3.2 모멘트, 좌-우측 전단력, 전-후방 전단력,압축력들에 대한 ANOVA 결과
 4. Discussion
  4.1 생체역학적 인자에 의한 비교
  4.2 작업 하중의 영향
  4.3 왼손과 오른손의 생체역학적 스트레스 비교
  4.4 한 손(왼손 또는 오른손) 작업과 양손 작업의생체역학적 스트레스 비교
  4.5 들기 작업에 대한 내리기 작업의 생체역학적스트레스 비율
  4.6 양손 작업 하중의 50% 해당하는 한 손 작업과양손 작업의 비교
 5. 결론 및 추후 연구 방향
 References

• 김홍기(경기대학교 공과대학 산업경영공학과) | Hong-Ki Kim Corresponding Author