• 산업융합연구
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• 제1권2호
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• pp.17-31
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• 2003

Many risk factors with the onset of Low Back Pain(LBP) have been identified, however, lifting out of Manual Material Handling(MMH) was the most important factor to the LBP. Injuries due to lifting took account for 34.0%(227,291) out of the total overexertion in MMH(668,084). The weight, vertical location, twist angle, lifting frequency, and lifting posture were reviewed in this study. Technical information for using the revised lifting equation to evaluate a variety of two - handled manual material handling tasks was suggested. To measure worker's fatigue in lifting task, Lifting Index Simulator(LIS) was create under the revised NIOSH(National Institute for Occupational Safety and Health) lifting equation. For the implementation of the LIS, data was collected in A company manufactures various paints in Si-Wha industrial complex, Kyunggi-Do. The results of the Lifting Index(LI) were analyzed by MANOVA to find the relation with lifting variables collected. It was found that horizontal distance, vertical distance, travelling distance and frequency were significant at the 0.01 level and weight was significant at the 0.05 level. The purpose of this paper is to reduce the chronical low back pain for the manual material handlers.

• 한국도로학회논문집
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• 제9권2호
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• pp.27-37
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• 2007

본 연구는 프리캐스트 콘크리트 포장 시공을 위하여 공장에서 미리 제작된 콘크리트 슬래브를 리프팅을 할 때 리프팅 위치에 따른 슬래브의 응력변화를 기준으로 슬래브의 손상을 최소화할 수 있는 가장 안전한 최적 리프팅 지점을 선정하기 위하여 수행되었다. 리프팅 시 슬래브의 응력분포를 분석하기 위하여 유한요소법을 이용한 모델을 사용하였으며 슬래브 규격은 시험시공에서 사용한 크기를 적용하였다. 리프팅은 항상 슬래브의 수직방향으로 수행하지는 않기 때문에 수직으로 리프팅 하였을 때와 $60^{\circ},\;30^{\circ}$로 경사각을 주어 리프팅 하였을 때의 응력변화 특성을 분석하였다. 또한 리프팅 지점은 항상 슬래브의 중간 깊이인 중립축의 위치가 아니기 때문에 중립축으로부터 7.5cm. 15cm만큼 수직편심을 주어 리프팅하였을 때의 응력변화 특성도 분석하였다. 그리고 실제 시공 시 지점부분에 보강을 하는 것을 염두하여 지점부 응력집중현상을 무시한 경우와 보강이 없을 경우의 응력집중현상을 고려한 경우로 나누어 분석하였다. 이러한 해석을 통해 리프팅 경사각과 편심에 따른 최적 리프팅 위치를 선정하였으며 미국의 PCI기준과도 비교 분석하였다.

• 대한인간공학회지
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• 제21권1호
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• pp.27-32
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• 2002

The objective of this study was to investigate the effects of fatigue, caused by frequent manual lifting. on lifting velocity and lifting acceleration. Ten male volunteers performed lifting at a rate of 4 times per minute, continuously, for two hours using the free-style posture A box($30cm{\times}30cm{\times}20$) with a fixed weight (15.9 Kg) was used as the load for lifting, Heart rate, oxygen consumption, and EMG were also measured to estimate the level of fatigue, The posture as well as acceleration was recorded. The results showed that the lifting acceleration at the end of two hour increased significantly (20%, p<0.001) compared to the acceleration after fifteen minutes of lifting. It was also found that subjects changed their lifting postures as the result of fatigue. All subjects also indicated pain in their upper legs and the lower back at the conclusion of the experiment.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1992년도 추계학술대회논문집
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• pp.18-21
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• 1992

The objective of this study was to investigate the effects of fatigue, caused by frequent manual lifting, on lifting velocity and lifting acceleration. Ten male volunteers performed lifting at a rate of 4 times per minute, continuously, for two hours using the free-style posture. A box $(30cm{\times}30cm{\times}20cm)$ with a fixed weight (15.9kg) was used as the load for lifting. Heart rate, oxygen consumption, and EMG were also measured to estimate the level of fatigue. The posture as well as acceleration was recorded. The results show that the lifting acceleration at the end of two hour increased significantly (20%, p<0.001) compared to the accleration after fifteen minutes of lifting. It was also found that subjects changed their lifting postures as the result of fatigue. All subjects also indicated pain in their upper legs and the lower back at the conclusion of the experiment.

• 한국전산유체공학회지
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• 제3권2호
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• pp.52-64
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• 1998

Numerical simulations on the flowfield of lifting chamber for Wing-In-Ground vehicle were performed using Fluent/UNS 4.2 software. The trend of lifting force in lifting chamber and parametric study of geometric and fluid variables were primarily investigated. Selected parameters for investigation are inlet velocity, height between chamber and water level, depth of the skirt, location of inlet, variaton of height at bow and stern. Also, air capturing capabilities from downstream of the propeller were evaluated at the air inlet. The lifting force was increased linearly with the increased of inlet velocity and nonlinearly with the decrease of height force was increased with increased depth. It turned out to have very minor effect on lifting force to change the location of air inlet for lifting chamber, installed on top surface. Tilting the vehicle when it was lifted, the lifting forces, generated in each case, showed no appreciable changes.

• 산업경영시스템학회지
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• 제23권56호
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• pp.93-102
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• 2000

Today, the number of automated machine has rapidly increased in industrial workplaces. Nevertheless, workers are often required to handle materials manually. Technical information for using the revised NIOSH lifting equation to evaluate a variety of two - handed Manual Material Handling (MMH) tasks was investigated. The NIOSH suggested the Lifting Index that provides a relative estimate of the level of physical stress associated with a particular manual lifting task. To measure operator's workload in lifting task, Lifting Index Simulator(LIS) was developed based upon the revised NIOSH lifting equation in this study. The purpose of this study was to develop LIS and use the NIOSH lifting equation in our workplace.

• 대한인간공학회지
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• 제30권5호
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• pp.597-603
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• 2011

Objective: The objective of this study was to compare one-hand and two-hands lifting activity in terms of biomechanical stress for the range of lifting heights from 10cm above floor level to knuckle height. Background: Even though two-hands lifting 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 are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lifting tasks using both a one-handed as well as a two-handed lifting technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lifting tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lifting tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 43%, as the workload was increased twice from 7.5kg to 15.0kg. For the right-hand lifting task, these were increased by the average 34%. For the two-hands lifting tasks, these were increased by the average 25%. The lateral shear forces at L5/S1 of one-hand lifting tasks, notwithstanding the half of the workload of two-hands lifting tasks, were very high in the 300~317% of the one of two-hands lifting tasks. The moments at L5/S1 of one-hand lifting tasks were 126~166% of the one of two-hands lifting tasks. Conclusion: It is concluded that the effect of workload for one-hand lifting is greater than two-hands lifting. It can also be concluded that asymmetrical effect of one-hand lifting is much greater than workload effect. Application: The results of this study can be used to provide guidelines of recommended safe weights for tasks involved in one-hand lifting activity.

• 대한인간공학회지
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• 제25권2호
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• pp.147-154
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• 2006

This study was conducted to evaluate the effect intentional contraction of abdominal muscles during lifting above shoulder on the muscles activities of the lower trunk and on the degree of lumbar extension. Fifteen healthy adult males were selected as test subjects. A 5kg weight was raised to the shoulder level, 20cm, and 40cm above the shoulder level. EMG activities of all muscles except the rectus abdominis were significantly greater when subjects were asked to contract their abdominal muscles intentionally during lifting(p<0.05). Degree of lumbar extension also significantly decreased with intentional abdominal contraction during the lifting. Also, degree of lumbar extension significantly increased with increase in lifting height(p<0.05). The results of this study show that intentional contraction of abdominal muscles during lifting above shoulder increases the EMG activities of external abdominis oblique, internal abdominis oblique, and erector spinae.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 추계학술발표논문집
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• pp.187-193
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• 2000

The purpose of this study was to reduce the chronical low back pain for the manual material handlers. The objectives of this study was to: (1) examine lifting variables, (2) analyze collected data, and (3) suggest lifting redesign recommendations in workplace. The data were collected in A company, manufactures various paints in Si-Wha industrial complex, Kyunggi-Do. It was found that Sb(horizontal distance), Sc(vertical distance), 54(travelling distance) and Sf(frequency) were significant at the 0.01 level and Sa(weight) was significant at the 0.05 level.

• 대한인간공학회지
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• 제25권2호
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• pp.197-204
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• 2006

The purpose of this study was to investigate the relationship between the cumulative fatigue of trunk muscles and the period of recovery time during repetitive lifting and lowering task with two different frequencies(4 times/min and 6 times/ min). Eight healthy males with no prior history of LBD(low back disorders) volunteered for this study. Subjects had 2, 3, 4, and 5 minutes recovery time respectively while they were preforming the lifting and lowering task at 15% level of MVC. EMG signals from six trunk muscles were collected and the fatigue level was analyzed quantitatively. In results, the fatigue levels of LES(left elector spinae), RLD(right lattissimus dorsi), LLD(left lattissimus dorsi), RRA(right rectus abdominis) and LRA(left rectus abdominis) were recovered when 3 minutes recovery time was given at 4 times/min frequency. However, the fatgue level of RES(right elector spinae) was recovered when 4 minutes recovery was given. On the other hand, when 6 times/min frequency was used, the RLD, LLD, RRA and LRA were recovered at 5 minutes of recovery time. But for RES and LES, it took longer than 5 minutes to be recovered. This results can be applied to design the adequate length of recovery time to control the cumulative fatigue of trunk muscles in industry with repetitive lifting and lowering task.