• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.807-812
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• 1995

In this study, comparisons were made among three representative methods for predicting compressive forces on the lumbosacral disc: LP-based model, double LP-based model and EMG-assisted model. Two subjects simulated lifting tasks that are normally performed in the refractories industry. In the refractories lifting tasks, vertical and horizontal distance, and weight of load were varied. To calculate the L5/Sl compressive forces, EMG signals from six trunk muscles were measured and postural data were recorded using the Motion Analysis System. The EMG-assisted model was shown to reflect well all three factors considered here. On the other hand, the compressive forces of the two LP-based models were only significantly affected by weight of load.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.50-54
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• 1999

In the process of designing a wheel balancer an ergonomic evaluation model has shown that manual tire handling onthe machine was often the major problem, The root of the problem lay in the design of machine's shaft which is influenced by the opeative handling task. Several methods were reviewed for determining the correct shaft' sizes but the Revised NIOSH Equation and the Lifting Stress Calculator were found to be the only suitable models for this study. An application of these mathematical models has shoed that the shaft length and the shaft height were the most critical measurement By analyzing these conclusion s the correct shaft size parameters became clearly defined.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.117-120
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• 2001

Low back pain has been known as the most frequent musuculoskeletal disorders in modern industrial society and cost by low back pain is increasing mon and more. The asymmetric lifting has been identified as a major risk factor of low back pain. In this study, the muscle activity and muscle exertion level during asymmetric load handling (without trunk flexion) was estimated. The results of normalized MVC measurement were decreased about 16％, 24％, 34％ respectively as the asymmetric angle was $30^{\circ}$, $60^{\circ}$, $90^{\circ}$. From the results of EMG measurement contralateral muscles were more active than ipsilateral muscles. RMSEMG values of right erector spinae muscles were decreased as the work posture went to 90$^{\circ}$ and those of left erector spinae muscles were increased until the asymmetric angle was 40$^{\circ}$ but decreased continually over 40$^{\circ}$. And for seven of subjects, activities of left and right latissimus dorsi muscles were maintained constantly, while for remainer, those were irregular.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.145-146
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• 2018

This study was performed to develop the lifting pallets for the application of smart skin system when remodeling the balcony of apartment house. For this purpose, the smart skin system based on IoT, combining window, BIPV, ESS, air purifier applied in this study was examined. The study developed and presented a foldable double pallet considering the load (about 2Ton) and specification (width 7m × height 2.6m × width 1.3m) of the smart skin system. In future research, it is necessary to verify the application of the foldable pallet in this study.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.96-100
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• 2012

Low back pain (LBP) is a major issue in modern industrialized society which is mainly caused by manual material handling (MMH) tasks. The objective of this study was to provide scientific data for establishing work standard for Korean workers throughout the laboratory experiment including some specific lifting tasks. Thirty male college students were recruited as participants. The maximum voluntary contraction (MVC), recommended weight limit (RWL), and psychophysical safety weight using Borg's CR-10 scale were studied. Results showed that the RWL was 8.4% MVC higher than the proposed psychophysical safety weight. Based on this result, it is suggested that the NIOSH lifting equation (NLE) should not be directly applied to Korean without reasonable modifications. The ratio of psychophysical safety weight to MVC was ranged from 20.1 to 26.4%. It is expected that use of the methodology in this study may provide better expectation of the work ability of Korean for reducing lower back pains caused by MMH.

• 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 Korean Society of Safety
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• v.38 no.4
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• pp.60-67
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• 2023

Various lifting slings are used in domestic industrial sites depending on the purpose, form, and environment. Each sling has its characteristics, and safe lifting work is possible when its performance meets the regulations. Therefore, this study analyzed domestic and foreign regulations and guidelines related to chain slings. It identified significant problems by analyzing the chain-sling-related disaster cases. The current status of chain slings used by various industries and the ways to improve chain sling safety were studied. The major chain sling issues were: 1) employing improper components to chains, 2) having different safety coefficients between the regulation and industrial standards, and 3) using chains unsuitable for lifting purposes. Based on these issues, the following measures were proposed to improve chain sling work safety: 1) revise the safety coefficient requirements under the Regulations on Occupational Safety and Health Standards, 2) disseminate specialized sling courses, and 3) strengthen on-site chain slings-related training. In the future, this study is expected to minimize chain use mistakes by unifying the safety coefficient related to chain slings and recognizing the importance of correctly selecting components employed in the chain.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.357-365
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• 2010

Workers in the agricultural industry have been exposed to many work-related musculoskeletal disorders. So, our objectives in this study were to measure and analyze worker's physiological bio-information to reduce musculoskeletal disorders in relation to agricultural works. We investigated worker's bio-information of physiological signals during the repeated lifting work such as body temperature, heart rate, blood pressure, physical activity, and heart rate variability. Moreover, we analyzed the workloads of lumbar spine during the repeated lifting work using the 3-axis acceleration and angular velocity sensors. The changes of body temperature was not significant, but the mean heart rate increased from 90/min to 116/min significantly during 30 min of repeated lifting work (p<0.05). The average worker's physical activity(energy consumption rate) was 206 kcal/70kg/h during the repeated lifting work. The workers' acute stress index was more than 80, which indicated a stressful work. Also, the maximum shear force on the disk (L5/S1) of a worker's lumbar spine in static state was 500N, and the maximum inertia moment was 139 $N{\cdot}m$ in dynamic state.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.91-99
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• 2010

In order to strengthen RC structures, various strengthening methods have been used. Particularly, external tendon strengthening method is very popular method to strengthen damaged structures in terms of efficiency, ease, economics. In this study, improved anchorage elements using the lifting hole were proposed to strengthen PSC or RC girder without any damage. Two types of anchorage elements were proposed and these elements were applied on six RC beams. Also, three types of existing anchorage elements were applied on three RC beams. Otherwise, any anchorage element was not applied on one RC beam to used as a control beam. To analyse behavior of these elements, static load tests were carried out. Test variables were anchorage shapes, prestressing level on the steel bar and tendon profiles. Deflections, strains and modes of failure were recorded to examine the strengthening effects of the beams. Ductility index and tendon stress were analyzed by comparing cracking load, yielding load and ultimate load. As a result, proposed anchorage elements using lifting hole were superior to existing anchorage elements in terms of strengthening effect and furthermore, they showed ductile behavior based on energy method.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.2
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• pp.104-113
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• 2005

A variety of ergonomic assessment methods of lifting tasks known as a major cause of work-related lower back pain have been used. But there is a limited information in choosing the most appropriate assessment method for a particular job and in finding out strengths and weakness of the methods. The purpose of this study was to assess and compare the ergonomic risks of lifting tasks in a marine diesel engine production industry by three lifting ergonomic assessment tools widely used: the National Institute for Occupational Safety and Health(NIOSH) Revised Lifting Equation(NLE), the Washington Administrative Code 296-62-0517(WAC), and the Snook Tables. Lifting index(weight of load/Recommended Weight Limit) of NLE($LI_{NLE}$) was above 1 at 34 tasks(75.6%) of a total number of 45 lifting tasks. LI of WAC($LI_{WAC}$) was above 1 at 11 tasks(24.4 %). LI of Snook Table($LI_{Snook}$) was above 1 at 29 tasks(64.4%). Thus, LI was high in orders of $LI_{NLE}$ > $LI_{Snook}$ > $LI_{WAC}$. There were significantly high correlations among three Lls(p<0.01). The correlation coefficients between $LI_{NLE}$and the other three Lls($LI_{WAC}$ and $LI_{Snook}$) were r=0.93 and r=0.88, respectively. The linear regression equations were y = 0.444x + 0.11(r=0.93) between $LI_{NLE}$ and $LI_{WAC}$, y = 0.93x + 0.008(r=0.88) between LI(NLE) and $LI_{Snook}$. The LI values by WAC was significantly lower than those by the other tools. The compared features, strength and limitation among these tools were described in this paper.