• 산업경영시스템학회지
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• 제25권1호
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• pp.9-13
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• 2002

The objective of this study was to analyze and make comparison between the physical responses such as oxygen consumption rate, heart rate, and EMG-measurement for lifting tasks. Lifting activities with three different working frequencies(5, 8, 11 lifts/min) and two different weights(10, 20kg) for a lifting range(from floor to 76cm height) were studied. It was found that theme are positive correlations between the oxygen consumption rate and the EMG-measurements on the region of law back. Even though these physical responses were influenced by work weights and work frequency, it was found that the work frequency plays more important role in making muscle fatigue than the work weight. From these finding it is suggested that the work frequency should be considered as a more influencing factor than the work weight as long as the weight belongs to the permissible range based on the viewpoint of the biomechanical criterion for designing a job of manual materials handling tasks.

• The Journal of Korean Physical Therapy
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• 제21권3호
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• pp.119-124
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• 2009

Purpose: The National Institute for Occupational Safety and Health (NIOSH) lifting equation (NLE) is a useful tool to ergonomically analyze a workload. The NLE has high reliability and it can assess tasks by analyzing the work process. The purpose of this case study was to try using the NLE to analyze the workload of transferring patients by physical therapists in the hospital setting. Methods: We observed a physical therapist (PT) transferring patients from a wheelchair to a tilt table and a therapeutic table in one day. Two types of patient transferring methods were evaluated; (1) the manual single person method of stand, pivot and transfer, and (2) manual two person lifting under the thigh and grasping the waist for totally dependent patients. Results: The NIOSH lifting indexes of a person grasping the waist during the manual two person lifting were 5.52~4.48 according to the patient's weight. The NIOSH lifting indexes were 3.34 and 4.48 for the tasks performed by the manual single person method. Conclusion: Because transferring patients is not done very frequently, patients transferring tasks by a PT are not included as one of the musculoskeletal disorder related risky work criteria of the Korea Ministry of Labor. But the NIOSH lifting indexes of a person grasping the waist during the manual two person lifting and the manual single person method were over the NIOSH recommended weight limit threshold.

• 한국건설관리학회논문집
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• 제18권2호
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• pp.58-70
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• 2017

초고층 건축공사에서 리프트카를 이용한 자재 양중 관리는 핵심적인 관리분야 중 하나이다. 기존 연구들은 양중계획의 기본 단위인 양중 사이클타임이나 리프트카의 운행효율은 기존 사례를 참고하여 적용하거나 관리목표로 설정하고 개략적으로 산정하는 한계가 있었다. 따라서 본 연구에서는 양중 사이클타임을 단축하고 가동율을 향상시키기 위하여 자재 양중작업 프로세스를 최적화하는 방법론 제안을 목표로 하였다. CYCLONE 모델을 변형하여 작업시간과 작업위치를 반영할 수 있도록 개선하고, 세부 작업을 조정하여 프로세스를 최적화 하는 방법론을 제안하였다. 이 방법론에 따라 양중작업 프로세스를 개선하고 민감도 분석과 현장 적용성 평가를 실시하였으며 초고층 현장에 적용하였다. 기존 작업 프로세스와 개선된 작업 프로세스를 양중 높이별로 시뮬레이션하고 이를 현장 적용 결과 데이터와 비교하여 양중작업 시간 단축과 가동율 향상 정도를 비교 분석하여 최적화 방법론의 효용성을 검증하였다.

• Safety and Health at Work
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• 제8권2호
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• pp.130-142
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• 2017

Background: Osteoarthritis of the knee is considered to be related to knee straining activities at work. The objective of this review is to assess the exposure dose-response relation between kneeling or squatting, lifting, and climbing stairs at work, and knee osteoarthritis. Methods: We included cohort and case-control studies. For each study that reported enough data, we calculated the odds ratio (OR) per 5,000 hours of cumulative kneeling and per 100,000 kg of cumulative lifting. We pooled these incremental ORs in a random effects meta-analysis. Results: We included 15 studies (2 cohort and 13 case-control studies) of which nine assessed risks in more than two exposure categories. We considered all but one study at high risk of bias. The incremental OR per 5,000 hours of kneeling was 1.26 (95% confidence interval 1.17-1.35, 5 studies, moderate quality evidence) for a log-linear exposure dose-response model. For lifting, there was no exposure dose-response per 100,000 kg of lifetime lifting (OR 1.00, 95% confidence interval 1.00-1.01). For climbing, an exposure dose-response could not be calculated. Conclusion: There is moderate quality evidence that longer cumulative exposure to kneeling or squatting at work leads to a higher risk of osteoarthritis of the knee. For other exposure, there was no exposure dose-response or there were insufficient data to establish this. More reliable exposure measurements would increase the quality of the evidence.

• 한국경영과학회지
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• 제42권3호
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• pp.1-12
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• 2017

In this paper, we generalize lifted inequalities to a 0-1 mixed-integer bilinear covering set with linear terms. This work is motivated by the observation that Generalized Bilinear Inequality (GBI) occurs in the Branch and Bound process. We find some conditions and prove the subadditivity of lifting functions for lifting to be sequence-independent. Using the theoretical results, we develop facet-defining inequalities for a GBI-defined set through three steps of lifting.

• 한국건설관리학회논문집
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• 제9권3호
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• pp.185-193
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• 2008

점차 대형화, 고층화되고 있는 공동주택공사에서 작업효율성을 향상시키고자 양중작업의 최적화를 위한 리프트 선정방식의 합리적 절차와 기준이 요구되고 있다. 따라서, 작업효율성 및 경제적 측면에서의 분석을 통하여 양중자재의 종류 및 규격, 건축물의 높이, 공사기간에 따른 건설용 리프트의 합리적 선정 및 운영을 위한 기준을 제시할 필요가 있다. 본 연구의 목적은 고층화 복잡화되고 있는 공동주택건설 현장여건에 따른 효율적 양중계획 및 관리를 위하여 대표적인 양중장비인 저속형과 중속형 리프트의 작업효율성과 경제성의 비교 분석을 통하여 최적의 선정을 위한 기초적 자료를 제시하는 것이다. 본 연구의 주요 결과는 40층 기준으로 중속형 리프트가 저속형에 비해 약 43%의 작업효율이 높은 것으로 분석되었다. 본 연구의 결과는 향후 공사의 용도, 규모, 형태, 조건 등에 알맞은 건설용 리프트 선정 기준/지침/규정을 마련하는 연구의 기초자료로 활용될 것으로 기대된다.

• 한국산업보건학회지
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• 제8권1호
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• pp.1-23
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• 1998

Work-related Low Back Pain(LBP) is one of tile most important Issues in the field of industrial safety and health. Particularly, manual lifting is known as a major cause of work-related LBP and impairment. Total number of 163 manual lifting tasks in motor assembly processes were investigated. The 1981 and the 1994 equations developed by National Institute for Occupational Safety and Health(NIOSH) were applied to evaluate potential hazards of lifting-related LBP. Comparisons between the 19R I and 1994 NIOSH criteria were made. The relationships between the NIOSH criteria and lifting-related LBP were also analyzed. The results of this study are as follows: 1. The values of Action Limit(AL) by the NIOSH 1981 lifting equation. Recommended Weight Limit(RWL) by the 1994 equation and the weight of the load handled at each manual lifting task were shown log-normal distributions. 2. LI'(the weight of tile load/AL) and LI(the weight of the load/RWL) were calculated estimate the physical stress imposed by each individual lifting task. As a result. 76.7% of the total LI' value exceeded 1 and 12.9% exceeded 3, and 84.7% of the total LI values exceeded 1 and 20.9% exceeded 3. 3. Bus 2 Department showed the highest rate of LI'>1 and LI>1 and Bus 1 Department showed the highest rate of LI'>3 and LI>3 4. In general, the RWLs by the 1994 equation were found lower than the ALs by the 1981 equation. It is assumed to he resulted from the fact that the 1994 equation includes methods evaluating asymmetrical lifting tasks and lifts of objects with less then optimal hand-container couplings, and also covers a larger range of work durations and lifting frequencies than the 1981 equation. 5. Significant correlations were found between LI' and incidence of LBP (R=0.734, p<0.05). LI and incidence of LBP(R=0.671. p<0.10) and load-weights and incidence of LBP(R=0.797, p<0.05). 6. Control measures are required to achieve the value of LI less than 1 for some tasks having high LI values. Engineering control is highly recommended for some tasks having the value of LI above 3.

• Safety and Health at Work
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• 제8권2호
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• pp.206-211
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• 2017

Background: Self-reported low back pain (LBP) has been evaluated in relation to material handling lifting tasks, but little research has focused on relating quantifiable stressors to LBP at the individual level. The National Institute for Occupational Safety and Health (NIOSH) Composite Lifting Index (CLI) has been used to quantify stressors for lifting tasks. A chemical exposure can be readily used as an exposure metric or stressor for chemical risk assessment (RA). Defining and quantifying lifting nonchemical stressors and related adverse responses is more difficult. Stressor-response models appropriate for CLI and LBP associations do not easily fit in common chemical RA modeling techniques (e.g., Benchmark Dose methods), so different approaches were tried. Methods: This work used prospective data from 138 manufacturing workers to consider the linkage of the occupational stressor of material lifting to LBP. The final model used a Bayesian random threshold approach to estimate the probability of an increase in LBP as a threshold step function. Results: Using maximal and mean CLI values, a significant increase in the probability of LBP for values above 1.5 was found. Conclusion: A risk of LBP associated with CLI values > 1.5 existed in this worker population. The relevance for other populations requires further study.

• 한국안전학회지
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• 제18권2호
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• pp.119-124
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• 2003

Despite rapid technological advance and increased automation facilities, many jobs and activities in our living require manual materials handling(MMH). These include wide variety of activities such as moving things, lifting bags. boxes or cartons, etc. Many studies found that handle could affect on maximum acceptable weight of lifting, but there were few studies f3r the effects of work posture and coupling in lifting tote box. This study performed that ten male college students were required to lift a tote box with and without handle for three postures (bending, straight, right angle posture). From the experiment, following results were obtained. (1) MVC reduced maximum 23% by type of handle. (2) MVC was highest in straight posture, but was lowest in right angle posture. (3) As a result of ANOVA, MVC paid attention to posture and coupling. (p<0.01) (4) To all handle types, biceps brachii activity was increased in right angle posture. but reduced in straight posture. (5) To all posture, biceps brachii activity was most lively in no handle. The results of MVC measurement, subjective rating, EMG analysis, statistic analysis showed that maximum acceptable weight of lifting was influenced by type of handle and straight posture was more comfortable than other postures. Based on these results, it was concluded that acceptable weight of lifting has to differ for work posture and coupling.

• 한국산업보건학회지
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• 제7권2호
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• pp.289-297
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• 1997

Work-related low back pain(below LBP) is one of the major cause of morbidity, disability, limitation of activity and economic loss. Therefore the work-related LBP is one of the major issue in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the effective control programs of work-related LBP. The subjects were male workers employed at the welding and metal factory. The data was collected by self-reported questionnaire, interview and checking abdomen muscular and grasping power for two days on October, 1993. The contents of questionnaire were as follow: the experience of LBP, general characteristics, physical characteristics, employment status, type of work and working environment. The number of cases was 104 with a history of work-related LBP, so the prevalence of work-related LBP was 35.0%, and the number of controls was 140 without any history of LBP. As a result, marital status, educational level, abdomen muscular power, tenure, category of job, satisfaction of job, working posture, satisfaction for table and chair and lifting materials showed a statistical significance between the case and control groups. 284 Lifting jobs were quantified by NIOSH lifting equation method and ergonomic computer modelling methods. There were no significant differences in the action limit and disc compression force between group with LBP and without LBP. But in the lifting frequency and cumulative disc compression force there were significant differences. Therefore work-related LBP should be prevented by the ergonomic and environmental control.