• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.3
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• pp.284-289
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• 2006

In 2003, Korean government made the 11 scopes of overburdened work[Ministry of Labor(MOL), Notification No. 2003-24] to prevent musculoskeletal disorders(MSDs). MOL Notification was established based on 'Washington Administrative Code 296-62-051, Ergonomics'. When initially investigating the contents, the labor unions and the specialists pointed out the possibility of devaluation on risk factors of MSDs. The present study aimed to compare the result of the NIOSH revised lifting equation(NLE) analysis with the MOL Notification(No.8, 9, 10) on manual lifting tasks. A study sample of 568 manual lifting tasks (automobile parts, foods, and tire manufacture) were evaluated for this study. All 502 tasks exceed lifting index(LI) of 1.0, but 276 tasks(55.0%) out of 502 tasks were evaluated non-over burdened work for musculoskeletal system by the MOL Notification. Particularly, 47 tasks(30.9%), in spite of exceeding LI of 3.0, were evaluated non-over burdened work. This study has shown the possibility of devaluation on risk factors of MSDs, when evaluated by MOL Notification. Therefore, it will be necessary to repeal or complement the scope of over-burdened work(MOL Notification) to prevent musculoskeletal disorders.

• The Journal of Korean Physical Therapy
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• v.21 no.3
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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.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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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.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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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.

• Journal of the Ergonomics Society of Korea
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• v.36 no.4
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• pp.325-341
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• 2017

Objective: The purpose of this study is to suggest the guidelines of operation phases to minimize injuries and musculoskeletal disorders in manual material handling (MMH) tasks through literature reviews. The guidelines are presented as the preparing phase, lifting phase, carrying phase, and lowering phase. Also, we summarized the non-numerical general guidelines for MMH tasks. Background: Manual material handling is still a main cause to musculoskeletal disorders. Method: Procedures of a literature review are classified into database selection, keyword search, title review, abstract review related to literature selection, guideline review and arrangement. A total 48 papers and books were analyzed in detail by title and abstract reviews. Results: In the preparing phase, we suggested the basic conditions in MMH, preparing procedure, clothing and protective equipment, and education. In the lifting and carrying phases, we recommended maximal acceptable weight by frequency and body posture. In the lowering phase, we suggested the lowest weight and safety body postures. Finally, we recommended general guidelines and guideline items for MMH. General guidelines are presented to suggest worker selection, technical education, and work design parts. Conclusion: We suggested the guidelines on the four operation phases of MMH tasks such as preparing, lifting, carrying, and lowering phases. Application: The findings of this study can be utilized as guidelines for proactive recommendations according to workers in MMH tasks.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.35-44
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• 2007

Work-related musculoskeletal disorders (WMSDs) are a major problem in industries in which manual materials handling is performed by workers. To prevent these WMSDs, it is necessary to understand the muscular strength capability and use this knowledge to design job and selection and assignment of workers. 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. However, a few researches have been done for one-hand lifting activity of manual materials handling tasks. The objective of this study is to compare one-hand and two-hands lifting strength in terms of static and dynamic strength of the lifting activity for the ranging from the height of knuckle to elbow. It is shown in this study that the isometric lifting strength of one-hand is ranging from 54.7 to 63.3% of the one of two-hands. However, it is found that there is no significant difference between a person's isometric lifting strength for left-hand and right-hand. It is also shown that there is no significant difference between the peak force under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Similar results were obtained for the peak acceleration and peak velocity under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Isometric lifting strength at the height of knuckle was ranging from 2 to 3 times of the dynamic peak force during sub-maximal lifting. It is concluded that the dynamic peak forces under the sub-maximal loading are not highly correlated with the isometric lifting strength in similar postures.

• Journal of Industrial Convergence
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• v.1 no.2
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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.

• Industrial Engineering and Management Systems
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• v.7 no.1
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• pp.90-98
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• 2008

This research selects the lifting task to be the main subject. Four experiments were designed to measure which among lifting postures, lifting heights, waist-belt, and breathing control significantly influences intra-abdominal pressure (Gallagher, 1991; Lavender, Andersson and Natarajan, 1999). The experimental results were taken to be the recommendations of the manual materials handling work design. The research findings reveal that the symmetrical stoop posture is the most significant to the intra-abdominal pressure within all lifting postures. When the lifting height is increased, the intra-abdominal pressure produced relatively goes up. Also, the combination of symmetrical stoop posture, waist-belt use, and inspiration and holding at the same time is the most efficient in carrying out lifting tasks. Simultaneously, the research discovers that for any posture, the volume of the intra-abdominal pressure is much bigger when using the waist-belt compared to when it is not used. Therefore, the waist-belt design for the lifting works might be the future research approach.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.153-159
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• 2005

The purpose of this study was to assess the ergonomic risks of lifting tasks in a marine diesel engine manufacturing industry using the National Institute for Occupational Safety and Health(NIOSH) Revised Lifting Equation(NLE). Average Lifting Index(LI=Weight of Load/Recommended Weight Limit) of a total number of 45 lifting tasks was $1.6{\pm}0.7$. The LIs were above 1 at 34 tasks(75.6%), and above 2 at 11 tasks(24.4%). Parts management showed the highest average LI value (LI=2.3) in all departments, which resulted from high frequency and heave load of lifting. The common and significant ergonomic risk factors in the processes were the heavy weight of diesel engine parts and the long horizontal distance. In addition, some lifting tasks had such potential risk factors as the long vertical distance, the high frequency of lifts or the long work duration.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.72-81
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• 2014

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.