• 한국CDE학회논문집
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• 제2권4호
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• pp.244-252
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• 1997

In this paper, arm-type lifting mechanism which is attached under the frame of truck is analyzed. The three types of motions which are divided into rotation, pure lifting and automatic tilting motions are analyzed kinematically. These motions are visualized by computer graphics using Visual Basic. This program will be used for designer to demonstrate the arm-type lifting mechanism before making real machines. Also this program can change design parameter interactively.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.20-22
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• 2005

In this study, deformation of flange of pedestal crane due to Lug welding and lifting. Thermo elasto-plastic analysis was performed using commercial FE code MSC/MARC. The accuracy control of roundness is critical to the final product assembly. Deformation is mainly occurs during Lug welding. So, we determine welding sequence and Lug space in order to reduce deformation. And we also investigate safety of lifting Lug during crane lifting.

• 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.

• 한국정밀공학회지
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• 제32권8호
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• pp.749-754
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• 2015

The purpose of this study is to conduct a comparative analysis of the right shoulder's muscle activity when lifting ipsilateral and contralateral legs during the Push Up Plus (PUP) exercise, which is a typical shoulder stabilizing exercise, and to provide effective data for a shoulder stabilization exercise. Upper trapezius, lower trapezius, levator scapula, supraspinatus, infraspinatus, deltoid posterior, serratus anterior and pectoralis major, which are eight main muscles of a shoulder, were analyzed for the left and right leg lifting by using an electromyogram (EMG). The study revealed that the muscle activities of the right shoulder's upper trapezius, levator scapula, supraspinatus, serratus anterior and pectoralis major were higher when lifting an ipsilateral (right side) leg, compared to lifting a contralateral (left side) leg. Therefore, lifting an ipsilateral leg can be an effective method for enhancing the maneuverability (mobility) of the right shoulder when lifting a single leg.

• 대한인간공학회지
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• 제16권3호
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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.

• 국제초고층학회논문집
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• 제9권3호
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• pp.301-306
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• 2020

In tall building construction, the appropriate control of lifting loads on tower cranes is critical in terms of the construction duration of structural works. The adoption of efficient construction methods can be the most effective way of minimizing the inputs of tower cranes and making a lifting plan and management easier. Based on actual data from a tall building project, this study comparatively analyzes lifting loads of tower cranes by the core structure preceding construction method (CSPCM) and the core structure succeeding construction method (CSSCM). The results revealed that the CSSCM could reduce up to about 56.3% of lifting loads for core works and significantly enhance lifting efficiency compared with the CSPCM. Consequently, this enabled a substantial reduction in the construction duration of structural works. This study provides a practical reference to assist engineers and managers in applying efficient construction methods and lifting equipment operation in tall building projects.

• 대한조선학회 특별논문집
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• 대한조선학회 2011년도 특별논문집
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• pp.82-89
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• 2011

In general, a number of lifting lugs have been used in shipbuilding industry and the D-type lugs are mainly used. The aim of this paper is to increase the cycle of the use and to reduce the size of lifting lugs to introduce lightweight shackle. In this study, nonlinear elasto-plastic analysis has been performed to confirm the ultimate strength of lifting lugs. In order to evaluate the proper design-load distribution around lug eye, the contact force between lifting lug and shackle pin has been realized by gab element model. Gap element modeling and nonlinear analysis are carried out using the finite element program MSC/PATRAN & ABQUS. Additionally the ultimate strength tests were performed to verify the structural adequacy of newly designed lifting lug and to insure safety of it. The D-10, 15, 20 & 40 ton models which are mainly used in the block erection are selected in the strength test. According to the results of the analysis and strength test, the ultimate strength of the newly designed lifting lugs has been estimated to exceed 3 times of design working load.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.279-282
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• 2008

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of the end rotation of the overhang due to the vertical load. When the up-lifting force exceeds the clamp force of the fastener clip, the rail pad is out of fastener, which makes decrease the serviceability of the railway, such as noise and vibration. Furthermore, it is possible to reduce the safety of the track as the longitudinal resistance. This study is focused on guideline suggestion to decrease up-lifting force in the fastener adjacent to the civil joint of slab track of bridge throughout the parametric analysis between the vertical spring stiffness of the fastener as the material approach, the space of fastener adjacent to bridge transition, the rigidity of the girder as the geometrical approach and up-lifting force under the train load.

• The Journal of Korean Physical Therapy
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• 제34권4호
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• pp.175-180
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• 2022

Purpose: Leg length discrepancy causes the posture deformation, gait asymmetry, and lower back pain. The purpose of this study is to investigate the correlation among functional leg length discrepancy (FLLD), muscle activity, muscle contraction onset time and vertical ground reaction force (vGRF) during simple lifting task. Methods: Thirty-nine subjects participated in this study. FLLD was measured from the umbilicus to medial malleolus of left and right leg using a tape. The subjects performed to lift a 10 kg box from the floor to chest. The muscle activity and muscle contraction onset time of rectus abdominis, erector spinae and rectus femoris was measured using EMG system and vGRF was measured by two force plate. Pearson correlation was used to fine out the correlation among FDDL, muscle activity, muscle contraction onset time and vGRF during simple lifting task. Results: Correlation between FLLD and difference of muscle activity of short-long side was very high (r>0.9) during simple lifting task. Correlation between FLLD and difference of muscle contraction onset time of short-long side was very high (r>0.9) during simple lifting task. And correlation between FLLD and difference of vGRF of short-long side was high (r>0.7) during simple lifting task. Conclusion: This study suggests that there is high correlation between FLLD and muscle activity, muscle contraction onset time, and ground reaction force during simple lifting task. Therefore, FLLD could negatively affect the postural balance.

• 한국전문물리치료학회지
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• 제31권1호
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• pp.1-7
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• 2024

Background: Using wearable passive back-support exoskeletons in workplace has attracted attention as devices that support the posture of workers, enhance their physical capabilities, and reduce physical risk factors. Objects: This study aimed to investigate the effect of a wearable passive back-support exoskeleton on the activity of the erector spinae muscles during lifting tasks at various heights. Methods: Twenty healthy adult males were selected as subjects. Electromyography (EMG) was used to assess the activity of the erector spinae muscles while performing lifting tasks at three distinct heights (30, 40, and 50 cm), with and without the application of the Wearable Passive Back Support Exoskeleton. EMG data were gathered before and after the application of the orthosis. Results: The use of the Wearable Passive Back Support Exoskeleton resulted in a significant decrease in muscle activity when lifting a 10 kg object from heights of 30 and 40 cm (p < 0.05). Additionally, there was a significant reduction in muscle activity when lifting from a height of 50 cm compared with that at lower heights (p < 0.05). Conclusion: The use of a wearable passive back-support exoskeleton led to a decrease in the activity of the erector spinae muscles during lifting tasks, irrespective of the object's height. Our results suggest that the orthosis we tested may help decrease risk of lower back injuries during lifting.