• 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.22 no.50
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• pp.65-73
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• 1999

Most psychophysical studies in manual material handling (MMH) have paid more attention to two-handed MMH activities than to one-handed MMH activities. Also, studies are involved only with single MMH activities - lifting, lowering, carrying, holding, pushing or pulling. Very few studies are reported on the determination of workers' capacities for combinations of one-handed MMH activities (lifting a box, then carrying the box, and lowering the box). The objective of this study was to find the psychophysical and physiological responses of human subjects from a simulated industrial task involving one-handed and two-handed combined tasks. The capacities that were determined as the maximum acceptable weight workloads for 1 hr work period for one-handed and two-handed combined tasks - lifting a box from floor to knuckle height, carrying the box for 4.3 m, and lowering the box from knuckle to floor height - were determined psychophysically under three frequencies: six handlings per minute, one handling per minute and one handling per five minutes. In addition to maximum acceptable weight, heart rate and RPE values on wholebody, back, and arm were also measured as responses.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.97-106
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• 2009

Many production methods are tried to enhance the productivity efficiency. Parallel connected floating cranes are one of the examples to lift mega-blocks quickly and efficiently. However, a general operation manual to operate parallel connected floating cranes and a method to consider risks during lifting operation are not confirmed. And if each floating crane is operated by itself, it is very hard to cooperate. Therefore, Synchronized operation system is installed to control parallel connected floating cranes simultaneously and to be informed of each floating cranes data. And weighting factor is calculated by considering all hazards during the operation and the general operation manual is confirmed based on the factor. This paper introduces the procedure for lifting operations by parallel Connected Floating Cranes using synchronized operation system, and its applications to lifting operation of a heavy cargo such as barge lifting test, floating dock installation and 900 ton goliath crane replacement operation, etc.

• Proceedings of the Safety Management and Science Conference
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• 2000.11a
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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.

• Journal of the Ergonomics Society of Korea
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• v.18 no.2
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• pp.1-9
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• 1999

The objective of this study was to make comparison of the physical work capacities(PWCs) for three different types of tasks. For this purpose, an ergometer exercise, a treadmill exercise, and lifting activities with four different frequencies (2, 5, 8, 11 lifts/min) for the lifting range from floor to 76cm were considered. Oxygen consumption rates and heart rates were measured during the exercises and lifting activities. The PWC values for ergometer exercise test was $2562.71ml-O_2/min$ and the one for treadmill exercise was $2874.89ml-O_2/min$. The value of lifting PWC increased from $1774.07ml-O_2/min$ to $2296.76ml-O_2/min$ as the lifting frequency increased from 2 to 11 lifts/min. The ratio of the lifting PWCs to the ergometer PWC increased from 69.36% to 89.77% as the lifting frequency increased. To the treadmill PWC, the ratio increased from 62.21% to 85.24% as the lifting frequency increased. From this result, it appears that the PWCs based on the lifting tasks rather than PWCs by ergometer or treadmill exercise should be considered to determine the physiological criterion for safe weights for lifting tasks. Therefore, the physiological criteria of the NIOSH Guideline should be reexamined.

• Journal of the Ergonomics Society of Korea
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• v.18 no.1
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• pp.1-12
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• 1999

The objective of this study was to investigate the metabolic energy consumption rate of the psychophysical Maximum Acceptable Weight of Loads (MAWLs) for different manual materials handling tasks. Lifting activities with four different lifting frequencies (2, 5, 8, 11 lifts/min) for a lifting range (from floor to 76cm height) were studied. The oxygen consumption rate and heart rate were measured or recorded while subjects were lifting their MAWLs. It was found that the relationship between MAWL and frequency can be described best by the exponential function with the R-sq value 0.9865 for this study. Psychophysical MAWL decreased from 22.38 to 7.48 kg, while the oxygen consumption rate with the MAWL increased from 717.8 to $1114.7m{\ell}-O_2/min$ as the frequency increased from 2 to 11 lifts/min. Heart rate also increased from 104.5 to 120.7 bpm. The ratio of oxygen consumption for the MAWL to the Physical Work Capacity (PWC) ranged from 28 to 43%. The MAWLs were greater than or equal to the Maximum Permissible Limits (MPLs) when the frequencies were higher than 8 lifts/min. It seems that the MAWLs by psychophysical approach when the frequencies were higher than 8 lifts/min tend to be overestimated from the viewpoint of the physiological criterion of the oxygen consumption rates. From these findings it is suggested that the NIOSH Guideline should not be directly applied to Korean without reasonable modifications.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.145-153
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• 2010

Activity of lifting has been a major issue in many research area related in manual materials handling tasks. However, the opposite activity of lifting, lowering, has received much less attention. It is known that 52% of all box-handling tasks were lowering in nature. The difference in stress between lifting and lowering activity is not well understood. A simple assumption that these two activities are very similar has been established and widely used. However, this simple assumption may be questionable. The objective of this study was to compare a lifting activity and a lowering activity based on the three different ergonomic approaches; (1) biomechanical, (2) physiological, (3) psychophysical approach. It was found that the stress of lowering activity was from 65% to 93%, from 87% to 97%, and from 87% to 96% according to the biomechanical, physiological, and psychophysical point of view, respectively. It is concluded from the result of this study that the stress of lowering activity is lower than that of the lifting activity. The maximum compressive force on the lumbro-sacral joint (L5/S1) was 158% and 108% respectively, for lifting and lowering activity of which the work load is the 58% of Action Limit. It is suggested that the NIOSH AL and RWL and biomechanical criteria should be reconsidered especially for the low frequency of lifting activities.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.25 no.1
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• pp.29-36
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• 2019

Background: This study was conducted to investigate the effect of leg lift difference on the serratus anterior muscle and the upper trapezius muscle when a subject with winged scapula performs a scapula protraction exercise in a four-leg crawling posture. Method: Twenty normal adults and 20 subjects with winged scapula participated in the experiment. Surface EMG recordings were collected from serratus anterior muscle and back trapezius muscle during scapula protraction exercises. Scapular winging is measured with the lifting distance of scapula retraction to the back using an electronic digital caliper. In two groups of four-leg crawling posture, the two legs support, the dominant leg lifting, and the non-dominant leg lifting, including the scapula protraction, were performed. To examine the difference between groups in the variance analysis, the Bonferroni correction was used (significance level ${\alpha}=.017$). Statistical significance level ${\alpha}$ was .05. Results: There was a significant difference in serratus anterior muscle and upper trapezius muscle during push-up plus exercise in leg lifting in four-leg crawling posture, but there were no significant differences in muscle activity between serratus anterior muscle and upper trapezius muscle, and there was no significant difference according to the presence or absence of scapular winging. Conclusion: For the shoulder stability of the ipsilateral side with the serratus anterior muscle, the leg-lifting posture is effective in the four-leg crawling, and also when a subject with winged scapula chooses an exercise, lifting the ipsilateral side of leg with scapula protraction exercises at the same time may have a positive effect on scapula dysfunction.

• Proceedings of the ESK Conference
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• 1995.04a
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• pp.106-110
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• 1995

A local manufacturing companyin which low back pain(LBP) complaints were frequently reported was selected, and regularly perfomed lifting tasks were investigated using questionnaires and the 1991 NIOSH lifting guide. Among several processes of manufacture in the company, three processes-forming, heating and packing-were studied, where most of tasks were perfomed through manual materials handling (MMH). Questionnaire surveys showed that anthropometric data such as stature, weight and someatotype did not affect and weight of load influenced significantly the incidence of LBP, and workers who expwrienced LBP was older than the inexperienced. In addition, safety education conducted at the company was found to be ineffective in preventing LBP injuries. Lifting indexes(LI) was ranged from 0.86 to 17.0 with an average of 4.49, which revealed that tasks performing in the selected factory were in danger of LBP, and should be ertonomically redesigned. The critical factor reducing LI was found to be the horizontal component in all three processes, and most of weight of load was heavier than load constant(23kg) of the 1991 NIOSH lifting equation in heating process and packing.

• Journal of the Ergonomics Society of Korea
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• v.16 no.3
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• pp.23-36
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• 1997

The objective of this study was to make a comparison of the oxygen consumption rates during the lifting activities and the physiological criteria of the recommended weights of RWL, AL, and MPL by NIOSH Guideline. The physical Work Capacity (PWC) based on the bicycle ergometer was 2562.71ml/min, and the one based on the treadmill was 2874.89ml/min for the college male students of Korea. Lifting activities with four different lifting frequencies(2, 5, 8, 11 lifts/min) for one lifting range from floor to 76cm height were studied. The oxygen consumption rates and the heart rates were measured or recorded while subjects were lifting the weight of RWL, AL, and MPL. The heart rates and the oxygen consumption rates increased as the frequency increased from 2 to lifts/min. However, those slightly decreased at the frequency of 11 lifts/ min. The measured oxygen consumption rates were ranging from 2.3% to 29.6% higher than the physiological criteria 620, 700, and 1000ml/min, respectively, of the RWL, AL, and MPL for all the lifting frequencies (5, 8, 11 lift/min) except 2 lifts/min. It si suggested that the physiological criteria of NIOSH Guideline should be based on the lifting PWC, which can consider the type of lifting activity and the frequency of the task, rather than using the PWC by ergometer or treadmill. The measured oxygen consumption rates were ranging from 13.26% to 40.11% higher than the values estimated using the models by Garg and Kim. From these findings it is suggested that the NIOSH Equation should not be directly applied to Korean without resonable modifications.