• Journal of Korean Institute of Industrial Engineers
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• v.12 no.2
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• pp.1-11
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• 1986

This study is concerned on computerized analysis of COG, torques and EMG amplitudes in weight-lifting motion. The results show that; (1) torques on major joints show a rather consistent relationship with respect to the sequence of four distinct motions in weight-lifting, (2) analysis of EMG amplitudes is a sensitive measure of both athlete's skill and his potential capability, and (3) range of COG variations can be used as indicator of motion stability, existence of undesirable posture, and target muscle for intensive training. A computerized routine, which includes analyses on COG, EMG and torque, is a scientific tool for coaching athletes. In addition, an Expert System which includes CAD routine was developed in order to promote better understanding for athletes and coaches.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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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.

• 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.

• Journal of the Korea Society of Computer and Information
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• v.23 no.7
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• pp.49-56
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• 2018

Virtual object weight perception is an important topic, as it heightens the believability of object manipulation in immersive virtual environments. Although weight perception can be achieved using haptic interfaces, their technical complexity makes them difficult to apply in immersive virtual environments. In this study, we present a visual pseudo-haptic feedback system that simulates and depicts the weights of virtual objects, the effect of which is weight perception. The proposed method recognizes grasping and manipulating hand motions using computer vision-based tracking methods, visualizing a Force Arrow to indicate the current lifting forces and its difference from the standard lifting force. With the proposed Force Arrow method, a user can more accurately perceive the logical and unidirectional weight and therefore control the force used to lift a virtual object. In this paper, we investigate the potential of the proposed method in discriminating between different weights of virtual objects.

• 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.25 no.2
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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.

• 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.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.76-80
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• 2001

The weight of shoes may serve as a determining factor of perceived comfort and feel to the consumer in their purchase and repurchase decisions of footwear. People, however, seem to have trouble in accurately judging the feeling of weight of shoes on their feet. This paper made a psychophysical study of subjects′ sensitivity to weight on their feet and in their hands. The experiment consisted of 3 tests according to the motions people make when they evaluate the feel of shoes: 1) vertical lifting of a shoe on the foot ("hefting" in on the foot) 2) swing the shod foot back and forth; 3) holding and lifting a shoe by hand ("hefting" it in the hand). The method of constant stimuli and magnitude estimation were used for the experiment with 20 subjects. Weber′s ratios and the power law exponents obtained for each of the three tests were 0.156 and 0.713, 0.108 and 0.970, and 0.065 and 1.249, respectively in the same order of the previously listed tests.

• 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.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.