• Journal of the Ergonomics Society of Korea
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• v.24 no.3
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• pp.11-27
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• 2005

The objectives of this study are to analyze representative wrist postures while using hand tools and parts at general assembly processes, to evaluate perceived discomfort on the wrist when external loads are present, and to suggest an evaluation and prediction model of perceived discomfort. Sixteen subjects participated in an experiment to appraise perceived discomfort. Three types of the wrist postures with five levels of non-neutralities were analyzed when five levels of external load were applied to each posture. The ANOVA results showed that the perceived discomfort of wrist postures was significantly affected by both the wrist posture and external load (p$<$0.001). It was also shown that some of the interactions between external loads and the wrist postures(Flexion/$Extension^*$Load, Flexion/$Extension^*$supination/pronation, ulnar/radial $deviation^*$supination/pronation) were significant(p$<$0.001). The result implies that a new posture classification scheme for workload assessment methods may be needed to reflect such effects of external load and wrist posture. A regression model of perceived discomfort was developed with respect to wrist posture and external load from the experimental data. A subsequent experiment revealed that the correlation coefficient between the predicted values of perceived discomfort from the model and the actual values obtained from the experiment was about 0.98. It is expected that the results help to properly estimate the body stress resulting from worker's postures and external loads and can be used as a valuable design guideline to analyze potential hazard of musculoskeletal diseases in industry.

• The Korean Journal of Applied Statistics
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• v.31 no.3
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• pp.353-366
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• 2018

This study uses mixed-effects models to predict thigh soft tissue artefact (STA), relative movement of soft tissue such as skin to femur occurring during hip joint motions. The random effects in the model were defined as STA and the fixed effects in the model were considered as skeletal motion. Five male subjects without musculoskeletal disease were selected to perform various hip joint rotational motions. Linear mixed-effects models were applied to markers' position vectors acquired from non-invasive method, photogrammetry. Predicted random effects showed similar patterns of STA among subjects. Large magnitudes of STA appeared on the points near the hip joint regardless of sides; however, small values appeared on the distal anterior.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1145-1151
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• 2010

In this paper, we discuss the design and simulation of a jumping-robot mechanism that is actuated by SMA (shape memory alloy) wires. We propose a jumping-robot mechanism; the structure of the robot is inspired by the musculoskeletal system of vertebrates, including humans. Each robot leg consists of three parts (a thigh, shank, and foot) and three kinds of muscles (gluteus maximus, rectus femoris, and gastrocnemius). The jumping capability of the robot model was tested by means of computer simulations, and it was found that the robot can jump to about four times its own height. This robot model was also compared with another model with a simpler structure, and the performance of the former, which was based on the biomimetic design, was 3.3 times better than that of the latter in terms of the jumping height. The simulation results also verified that SMA wires can be suitable actuators for small jumping robots.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.33-40
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• 2021

Purpose : The fascia is the body's largest sensory organ affected by mechanical stimuli such as pressure. Fascial distortion model (FDM) is one of the fascia treatment techniques, and it is based that most musculoskeletal problems are caused by three-dimensional distortion of the fascia. Until now, some studies have been conducted to investigate the effect of FDM, but it is still not enough. In this study, among the six techniques of FDM, trigger band (TB) and cylinder distortion (CyD) were applied to the forearm to investigate the immediate effect on the maximal grip strength, force sense and range of motion. Methods : 22 healthy adults in their 20s and 30s participated. Before and after the application of FDM, maximal grip strength, force sense and range of motion were measured. For analysis, a paired t-test was performed, and the significance level was set to p<.05. Results : After FDM, there were a significant differences that increased the force sense and the range of motion (p<.05). But the maximal grip strength did not show a significant difference (p>.05). Conclusion : The results of this study, the FDM did not affect maximal grip strength, but it was shown to increase the sense of force and range of motion. We assumed that it is the result of the changes in the states of the fascia and changes in the activity of mechanical receptors induced by pressure and stretch from FDM application.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.72-78
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• 2015

According to the report of the WHO, workers have been exposed to much job strain such as job load, responsibility, role, interpersonal conflict etc. In Korea, studies on job strain started to become active from 1990s and now hundreds of studies are actively under going or publishing so that the studies are contributing to development and improvement of job strain. Representative measurement models of job strain are Job Strain Model of Karasek, Job Stress Model of NOISH, Korea Occupational Stress Scale, JSQ(Job Stress Questionnaire), K-OSI(Korea Version of Occupational Stress Inventory) etc. (Lee Kwan-Suk, 2012 ; KOSHA, 2003). Among them, Job Strain Model of Karasek had been loved by many researchers of job strain before Korea Occupational Stress Scale was developed. Job Strain Model of Karasek had been fitted to Korean style and then, used to analyze job strain of Korean people so that this Scale highly contributed to seeking relationship with cardiovascular disease, musculoskeletal disease caused by job, smoking, drug, alcohol poisoning, and pulse(Lee Kwan-Suk, 2012). But as this Model was studied and developed based on foreign culture and life pattern, a model fit to Korea was developed to measure job strain for Korean people, which is Korea Occupational Stress Scale now most frequently used in measuring job strain. Accordingly, after this study made questionnaire survey about same population using the two methods used most frequently in measuring job strain, the study investigated what features appeared, what correlations appear between two models, and comparatively analyzed characteristics each independent and dependent variable. Based on this, the study aimed to exactly express job strain of Korean people. The subjects of the study were a population of 233, and Karasek's Questionnaire and KOSS's Questionnaire were surveyed at the same time. The results were analyzed by statistical program to obtain significant difference between two models. Four particular groups were divided with Job Strain Model of Karasek and the four particular groups were measured with Korea Occupational Stress Scale. And job strain come from combination of two models was measured, with which new comparative analysis method was suggested.

• The Korean Journal of Rehabilitation Nursing
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• v.12 no.1
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• pp.5-15
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• 2009

Purpose: The purpose of this study was to explore the concept of deconditioning within the field of nursing allied health sciences. Method: The concept analysis method described by Walker and Avant(1995) was used. Critical attributes, antecedents, consequences, and empirical referents were identified. Also model, borderline, contrary and related cases were proposed. Results: The definition of concept 'deconditioning' was a decrease in the function of general system that occured after long periods of immobility and might be marked by frail upon return to normal conditions. The attributes of deconditioning were as follows; 1) the deconditioning was caused by lengthening of physical inactivity; 2) the deconditioning state was resulted by respiratory system, cardiovascular system, musculoskeletal system, hematologic system and generalized manifestation; 3) the deconditioning state could be reconditioned. 4) The reinforced functions by exercise could be compromised by physical inactivity. Conclusion: Deconditioning is important concept in nursing practice since it occurs commonly in any patients who lack physical activity for long time and affects many aspects of clinical outcomes, but it could be reversible by nurses' efforts.

• Journal of International Academy of Physical Therapy Research
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• v.2 no.2
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• pp.274-280
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• 2011

This study was designed to analyze repetitive dorsiflexion and plantarflexion exercises in ankles have effects on the muscle tones of triceps, vastus medialis and gastrocnemius. 25 healthy woman volunteers(ankle dorsiflexion exercise group: 13, ankle plantarflexion exercise group: 12) participated in the two ankle exercise models, which have performed 3 times a week for 3 weeks. Myotonometer was used to measure the muscle tones of the triceps, vastus medialis, gastrocnemius muscles, and measurements were performed before and after the application of the each exercise model. Repeated measured paired t-test and independent t-test was used to determine a statistical significance. The group of repetitive dorsiflexion exercise of the ankle have effects on the muscle tones of triceps, vastus medialis and gastrocnemius (p>.05). The group of repetitive plantarflexion exercise of the ankle have effects on the muscle tones of triceps, vastus medialis and gastrocnemius(p>.05). The groups of repetitive dorsiflexion and plantarflexion exercise of the ankle have effects on the muscle tones of triceps, vastus medialis and gastrocnemius(p>.05).

• Journal of the Ergonomics Society of Korea
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• v.23 no.4
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• pp.45-56
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• 2004

The purpose of this study is to evaluate perceived discomfort of working postures in terms of upper body (back, shoulder, and elbow) flexions when an external load varies. Eighteen subjects participated in an experiment of appraising perceived discomfort of varying upper body postures with three levels of external loads given. The ANOVA results showed that the perceived discomfort of upper body postures was significantly affected by the external load. It was also apparent that the interactions between external load and upper body posture were significant (p< 0.001). The result implies that a new posture classification scheme for workload assessment methods may be in need to reflect such interactions between external load and upper body posture. In order to support the statement, a regression model of perceived discomfort of upper body postures obtained from the experiment was developed and compared to that of perceived discomfort of seven work-related postures found in automobile assembly operations. The correlation coefficient between predicted and actual values of perceived discomfort was about 0.96. It is expected that the result help to properly estimate the body stress resluting from worker's postures and external loads and can be used as a valuable design guideline on preventing work-related musculoskeletal diseases in industry.

• Safety and Health at Work
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• v.8 no.2
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• pp.206-211
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• 2017

Background: Self-reported low back pain (LBP) has been evaluated in relation to material handling lifting tasks, but little research has focused on relating quantifiable stressors to LBP at the individual level. The National Institute for Occupational Safety and Health (NIOSH) Composite Lifting Index (CLI) has been used to quantify stressors for lifting tasks. A chemical exposure can be readily used as an exposure metric or stressor for chemical risk assessment (RA). Defining and quantifying lifting nonchemical stressors and related adverse responses is more difficult. Stressor-response models appropriate for CLI and LBP associations do not easily fit in common chemical RA modeling techniques (e.g., Benchmark Dose methods), so different approaches were tried. Methods: This work used prospective data from 138 manufacturing workers to consider the linkage of the occupational stressor of material lifting to LBP. The final model used a Bayesian random threshold approach to estimate the probability of an increase in LBP as a threshold step function. Results: Using maximal and mean CLI values, a significant increase in the probability of LBP for values above 1.5 was found. Conclusion: A risk of LBP associated with CLI values > 1.5 existed in this worker population. The relevance for other populations requires further study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.8
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• pp.913-920
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• 2012

An efficient 3D finite element walking model that considers the detailed shapes of muscles, ligaments, bones, skin, and soles was developed based on a real computed tomography (CT) scan image of a foot, and nonlinear contact analyses were performed to investigate pressure changes. The highest pressure occurs at the rear bottom of the foot when standing and walking. The pressure on the outsole with a curved foot bottom surface is lessened and distributed over a wider area than in the case of a flat outsole. The result shows that a shoe sole shape optimized for diabetes patients can relieve the foot pressure concentration and prevent further worsening of symptoms.