• 산업경영시스템학회지
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• 제33권4호
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• pp.38-44
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• 2010

We investigated the effects of trunk twist on postural stability during manually handling flat ties. Ten male subjects participated in this study. While handling 5kgf and 10kgf bundles of flat ties respectively, their centers of pressure (COPs) were measured under two levels of body position (twisted and fixed), two levels of direction (left and right), and three levels of object position ($30^{\circ}$, $45^{\circ}$, and $60^{\circ}$). Subjects' postural stability was quantified by calculating the sway length. Results showed that the effect of different object position was significant on postural sway length in subject's medio-lateral axis. Post-hoc multiple comparions revealed that, under the 5kgf load condition, the sway length was increased significantly as the object position increased to $45^{\circ}$. Under the 10kgf load condition, however, the sway length was increased significantly at the object position of $60^{\circ}$. Actual or potential applications of this research include guidelines for the design of working posture evaluation techniques.

• 한국운동역학회지
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• 제15권1호
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• pp.45-61
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• 2005

Stance is defined as any state in which the total mass of the body is supported by the feet. In order to maintain stance, the sum of gravito-inertial forces acting on the body must be registered by equal and opposite forces at the region of contact between the organism and the support surface. Balance is controlled by applying forces to the surface of support so as to maintain the body's center of mass vertically above the feet. for a muIti-segment organism, there can be a variety of ways in which balance can be controlled, since movements of different body segments can have similar effects on the control of balance. In general, the organism tends to have a body configuration that is aligned with gravito-inertial force when there are no external forces acting on it. If any segments of the body are not aligned with gravito-inertial force vector, a torque on that segment would tend to move the body's center of mass. The maintenance of postural stability is accomplished in humans by a complex neural control system. This requires organizing integrating and acting upon visual, vestibular, and somatosensory input, providing orientation information to the postural control system. The information necessary to control and coordinate movement is provided by the visual sense of eye position with respect to the surrounding surface layout, the vestibular sense of head orientation in the gravito-inertial space, and the somatic sense of body segment position relative to one another and to the support surface. In this study, perception and action capability was examined from various points of view. The underlying assumption of the study was that the change of postural configuration could be effected by organism, environment and task goal.

• 대한안전경영과학회지
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• 제16권1호
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• pp.119-127
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• 2014

This study tried to develop a basis for quantitative index of working postures associated with WMSDs (Work-related Musculoskeletal Disorders) that could overcome realistic restriction during application of typical checklists for WMSDs evaluation. The baseline data(for a total of 603 jbs) for this study was obtained from automobile manufacturing company. Specifically, data for back posture was analyzed in this study to have a better and more objective method in terms of job relevance than typical methods such as OWAS, RULA, and REBA. Major statistical tools were clustering, logistic regression and so on. The main results in this study could be summarized as follows; 1) The relationship between working posture and WMSDs symptom at back was statistically significant based on the results from logistic regression, 2) Based on clustering analysis, three levels for WMSDs risk at back were produced for flexion as follows: low risk(< $18.5^{\circ}$), medium risk($18.5^{\circ}{\sim}36.0^{\circ}$), high risk(> $36.0^{\circ}$), 3) The sensitivities on risk levels of back flexion was 93.8% while the specificities on risk levels of back flexion was 99.1%. The results showed that the data associated with back postures in this study could provide a good basis for job evaluation of WMSDs at back. Specifically, this evaluation methodology was different from the methods usually used at WMSDs study since it tried to be based on direct job relevance from real working situation. Further evaluation for other body parts as well as back would provide more stability and reliability in WMSDs evaluation study.

• 산업융합연구
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• 제22권2호
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• pp.97-103
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• 2024

본 연구의 목적은 비만 뇌졸중 환자의 균형 훈련이 체성분과 균형 능력 회복에 미치는 영향을 살펴보는 것이었다. 운동 프로그램은 비만군과 정상 체중 군을 동일하게 실험군(obesity)과 대조군(정상체중)으로 나누어 하루 30분, 일주일에 5일 동안 균형 훈련을 실시했다. 실험군과 대조군 모두 사전, 사후 체성분과 BSS(Biodex Medical Systems)를 8주간 수집하였다. 그 결과 그룹 내 체성분 자료를 비교해 보면 비만군은 모든 매개변수에서 유의한 차이를 보였다(p<.05). 또한 그룹 간 모든 매개변수 간에도 통계적인 차이를 보였다(p<.05). LOS(Limits Of Stability)의 그룹 내 자료를 비교해 보면, 비만군은 '후면'과 '좌측'을 제외한 모든 매개변수에서 유의한 차이를 보였다(p<.05). 그룹 간 자료에서 '전방' 매개변수는 유의한 차이를 보였다. PS(Posture Stability)의 그룹 내 자료를 비교해 보면, 비만군은 모든 매개변수에서 유의한 차이를 보였고(p<.05), 그룹 간 PS(Posture Stability) 결과는 'Med/lat'(p=.000)만으로 유의한 차이를 보였다. 이상의 결과를 종합해 보면, 균형 훈련이 비만이 있는 뇌졸중 환자의 균형 능력 및 체성분에 영향을 미치는 것으로 나타났다.

• 재활복지공학회논문지
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• 제7권2호
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• pp.63-68
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• 2013

장애인들이 많이 사용하고 있는 보조기구 중의 하나인 수동휠체어는 KS규격인 KS P ISO 7176-5의 치수 규격을 따르고 있다. KS P ISO 7176-5의 경우 국제 규격인 ISO 7176-5의 규격을 기술적 변경 없이 그대로 사용하고 있다. 하지만 국제규격의 경우는 외국의 신체사이즈를 기준으로 수동휠체어에 대한 크기를 지정하기 때문에 한국에서 사용하기에는 적합하지 않다. 실제로 기술표준원에서 조사한 인체치수 조사 자료와 현재 KS P ISO 7176-5의 규격을 비교한 결과 팔걸이 높이를 제외한 좌석의 높이, 좌석면의 너비, 좌석면의 깊이, 등받이 높이의 경우 KS P ISO 7176-5의 크기가 컸고, 팔걸이 높이는 KS P ISO 7176-5의 크기가 낮았다. 이러한 경우 사용자가 장시간 사용하게 되면 안정성이 감소되고, 사용자의 골반 회전이 쉬워져서 자세가 불안정해지고, 오금이 좌석의 모서리에 닿아 오금과 장딴지에 압력이 가해지고, 자세가 앞으로 당겨서 앉는 자세가 되어서 등이 구부정한 자세가 된다. 또한 몸이 앞이나 옆으로 기울어지는 자세가 되어서 올바른 자세로 유지할 수 없게 된다. 이러한 문제점이 계속 지속이 된다면 사용자의 신체에 무리가 올 수 있다. 이 논문에서는 한국의 장애인 치수에 대한 조사를 하여 올바른 휠체어 치수를 연구하여 제안하였다.

• 한국운동역학회지
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• 제26권3호
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• pp.285-292
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• 2016

Objective: This study collected data on muscle fatigue and ground reaction force during walking to provide a basis for development of custom-fitted outdoor walking shoes. The study analyzed an upright body exercise program using spine stabilization technique to determine the effect on foot plantar pressure in archers, demonstrate the effectiveness of upright body exercise, and develop a new, effective, and efficient training program. Method: A 12-week upright body exercise program was evaluated for the effect on plantar pressure in archers. Ten prize-winning archers (3 men, 7 women) in B metropolitan city, each with ${\geq}10years$ of experience, were given an explanation of the content and purpose of the program, and provided informed consent. Upright body exercise was performed 3 times a week for 12 weeks. A resistive pressure sensor was used to measure foot plantar pressure distribution and analyze quantitative information on variation in postural stability and weight shifting in dynamic balance during shooting, as well as plantar pressure in static balance with the eyes open and closed. Results: There were no significant differences in foot plantar pressure before and after participation in the exercise program. There was no statistically significant difference in foot plantar pressure in static balance with the eyes open or closed, or in foot plantar pressure in dynamic balance during shooting. Conclusion: An upright body exercise program had positive effects on foot plantar pressure in static and dynamic balance in archers by reducing body sway and physical imbalance during shooting and with eyes closed. This program is expected to help archers improve their posture and psychological state, and thereby improve performance.

• 로봇학회논문지
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• 제13권2호
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• pp.103-112
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• 2018

In this paper, a high performance underwater vehicle which can be manufactured at low cost is designed and fabricated, and its performance is verified through experiments. To improve efficiency, the Myring equation is used to design the appearance and the duct structure including the thruster is planned to increase the propulsion efficiency while reducing the drag force. Through various methods, it is secured stable waterproof performance, and also is devised to have high speed movement and turning performance. The developed underwater vehicle is equipped with a high output BLDC motor to achieve a linear speed of up to 2 m/s and can change direction rapidly with stability through four rudders. The rudders are driven by coupling a timing belt and a pulley by extending the axis of a servo motor, and are equipped at the end of the body to turn heading. In addition, for stable posture control, the roll keeps its internal center of gravity low and maintains its stability due to restoring force. By controlling the four rudders, pitch and yaw are handled by the PID controller and show stable performance. To investigate the horizontal turning performance, it is confirmed that the yaw rate controller is designed and stable yaw rate control is performed.

• 대한인간공학회지
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• 제25권3호
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• pp.1-15
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• 2006

Loss of postural balance can possibly lead to increased risk of slips and falls in work places. Present study was performed to investigate the effects of noisy environments on postural stability during standing. It is known that a sound is characterized by the frequency and pressure level of the sound. Therefore, effects of the frequency and pressure level on postural stability were of primary concern. Ten male subjects participated in the experiment. Subject's center of pressure(COP) position was collected on a force plate while they were exposed to different frequency and pressure levels of the sound. Measured COP was then converted into the length of postural sway path in both anterior-posterior(AP) and medio-lateral(ML) axis. Results showed that the length of sway path in AP axis was significantly affected by the frequency of sound. The length of sway path was lowest at frequency level of 2000Hz and increased below and above this frequency range. The sound pressure level, however, did not significantly affect the postural sway length in both AP and ML axis. The results imply that industrial workers in noisy environments should be aware that their abilities of postural balance can be disturbed significantly.

• 한국해양공학회지
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• 제26권5호
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• pp.47-54
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• 2012

In this study, numerical simulations were performed to evaluate the current loads acting on the multi-legged underwater robot "Crabster" with a variety of incident angles using the ANSYS-CFX package. The Reynolds-averaged Navier-Stokes equations were solved to simulate the fluid flow around Crabster to calculate the forces and moments induced by incoming currents with various angles. First, to assess the posture stability of the body, the forces and moments were calculated with various incident angles when the current acted in the vertical and horizontal directions. Next, two forms of legs (box and foil types) were evaluated to determine the hydrodynamic force variation. Finally, the current forces and moments acting on the Crabster body with the legs attached were estimated.

• 한국정밀공학회지
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• 제27권2호
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• pp.130-136
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• 2010

For stability analysis of the lumbar spine, the hypothesis presented is that the disc has stress sensors driving feedback mechanism, which could react to the imposed loads by adjusting the contraction of the muscles. Fusion in the motion segment of the lumbar spinal column is believed to alter the stability of the spinal column. To identify this effect finite element (FE) models combined with optimization technique was applied and quantify the role of each muscle and reaction forces in the spinal column with respect to the fusion level. The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Vertebral body and pelvis were modeled as a rigid body and the rib cage was constructed with rigid truss element for the computational efficiency. Spinal fusion model was applied to L3-L4, L4-L5, L5-S1 (single level) and L3-L5 (two levels) segments. Muscle architecture with 46 local muscles was used as acting directions. Minimization of the nucleus pressure deviation and annulus fiber average axial stress deviation was selected for cost function. As a result, spinal fusion produced reaction changes at each motion segment as well as contribution of each muscle. Longissimus thoracis and psoas major muscle showed dramatic changes for the cases of L5-S1 and L3-L5 level fusion. Muscle force change at each muscle also generated relatively high nucleus pressure not only at the adjacent level but at another level, which can explain disc degeneration pattern observed in clinical study.