• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.648-651
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• 2004

Biped robot has better mobility than other mobile robot, but it is hard to maintain balance during walking. In order to maintain balance, stability analysis is a key point for a biped robot. The zero moment point analysis has been used most in stability analysis. In this paper, we propose different method of stability analysis using wrench system. It is possible to generate a wrench system by applying a force along an axis in space and simultaneously applying a moment about the same axis. Wrench system is equivalent to a force and moment applied along the same axis. We compare the result of wrench system analysis with that of zero moment analysis in biped robot stability using simulation program.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.4
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• pp.423-432
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• 2012

PURPOSE: The purpose of this study was to investigate balance changes in young patients with neck pain by comparing postural sway velocity and velocity moment between young patients with neck pain and healthy subjects. METHODS: The cross-sectional study enrolled fifteen young patients with over 3-month duration of the neck pain and twelve healthy subjects between the ages of 20 and 30 years old. All subjects were measured their postural sway velocity and velocity moment during quiet standing with eyes open and eyes closed conditions. We compared the differences of postural sway velocity and velocity moment between neck pain patients and healthy subjects, and between eye open and eye close. RESULTS: Significant differences were evident in the anteroposterior and mediolateral sway velocity, and velocity moment of center-of-pressure (COP) between patients with neck pain and healthy subjects (p<.05), and in patients with neck pain in the eyes open and eyes closed conditions (p<.05). CONCLUSION: These results indicate that the balance of young patients with neck pain was worse than healthy subjects during quiet standing, and was especially lessened in the absence of vision. The finding may inform management program to decrease the balance deficits in young patients with neck pain.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.479-486
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• 2010

The purpose of this study was to determine the effects of high-heeled shoe on the quiet standing and gait balance. Twenty women (mean height: $161.6{\pm}3.3\;cm$, mean body mass: $53.8{\pm}6.3\;kg$, mean age: $23.8{\pm}2.7$ yrs..) who were without history or complain of lower limb pain took part in this study. They were asked to stand quietly on a force platform for 30 sec and walk on it at their preferred walking speed (mean speed $3.14{\pm}0.5\;km/hr$.) with wearing three different high-heeled shoe, 3, 7, 9 cm high for collecting data. Data were randomly recorded to collect two trials for quiet standing and five trials for walking The parameters to have been analyzed for comparison between three conditions of the height of high-heeled shoe were COP(Center of Pressure) range, COP velocity, sway area, and free moment on the static balance and COP range, COP velocity, and free moment on the dynamic balance. In this study, high-heel height affected on the COP range and velocity in the ante-posterior direction during walking, dynamic balance, but didn't affect on the quiet standing, static balance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.261-266
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• 2003

The present paper theoretically investigates characteristics of moment balance of a tilting-pad thrust bearing. Pressure of lubricant film of the bearing was computed using tile finite element method, and average film temperature was estimated from the heat balance over a pad. From the investigation, it has been found that different two sets of tilt angles satisfy moment equilibrium of the pad about tile pivot for a given pivot location. The tilt angles converged depend upon initial tilt angles assumed. Quite different bearing performance, including load capacity, film thickness, and temperature, is shown to be obtained based on choice of the initial tilt angles.

• Tribology and Lubricants
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• v.20 no.3
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• pp.152-156
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• 2004

The present paper theoretically investigates characteristics of moment balance of a tilting-pad thrust bearing. Pressure of lubricant film of the bearing was computed using the finite element method, and average film temperature was estimated from the heat balance over a pad. From the investigation, it has been found that different two sets of tilt angles satisfy moment equilibrium of the pad about the pivot for a given pivot location. The tilt angles converged depend upon initial tilt angles assumed. Quite different bearing performance, including load capacity, film thickness, and temperature, is shown to be obtained based on choice of the initial tilt angles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.418-424
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• 2019

The present study investigated the effects of the moment arm length on balance and walking when carrying a backpack. In total, 30 normal adults without orthopedic and neurological injuries were assessed. For each subject, balance and gait were measured under three conditions: 1) the no backpack condition, 2) the general backpack condition, and 3) the decreased length of moment arm backpack condition. There were significant differences in the center of the pressure area and velocity between the three conditions, whereas there was no significant difference in the center of the pressure area and velocity according to the moment arm length. There were significant differences in double limb support time and walking velocity under the three conditions, and there was a significant difference only in double limb support time according to the moment arm length. The results of the present study showed that a change in the length of the moment arm can be helpful for walking when carrying a backpack.

• PNF and Movement
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• v.13 no.3
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• pp.119-125
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• 2015

Purpose: The current study seeks to examine the effects of stabilizing reversal(SR) and rhythmic stabilization(RS) in proprioceptive neuromuscular facilitation (PNF) techniques on static balance in normal female adults. Methods: Subjects included 20 healthy women in their 20s. They were randomly divided into SR and RS groups. To assess static balance before and after PNF intervention, the good balance system was used to measure the interior and exterior center of pressure (COP) movement distance, front and rear COP movement distance before and after the intervention, and velocity moment. Results: Interior and exterior COP movement distance, front and rear COP movement distance, and velocity moment decreased in the SR group, but no statistically significant differences were observed. In the RS group, the interior and exterior COP movement distance declined without any significant difference, while the front and rear COP movement distance and velocity moment significantly decreased. The interior and exterior COP movement distance, front and rear COP movement distance, and velocity moment declined more in the RS group than in the SR group. Conclusion: The findings of the current study indicate that the RS technique is more effective than the SR technique for improving the balance ability of healthy female adults. The results of this study can thus be utilized in the selection of effective interventions for improving the balance ability of healthy female adults.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.15 no.1
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• pp.49-57
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• 2009

Purpose : To evaluate the effects hip abductor strengthening exercise using elastic band on static balance. Methods : The subjects consisted of twenty healthy people. The subjects were divided into two group. The control group(n=10) received no exercise and/or stimulation. The elastic band strengthening exercise(E/E) group(n=10) performed hip abductor for strengthening exercise using elastic band. E/E group were accomplished during 6weeks(3day/week, 30-40min/day). All tests were completed before and after experiment. The static balance ability was measured by normal standing when eye open and close on GOOD BALANCE System, respectively. For each case, the experimental data were obtained in 3 items: mean X speed, mean Y speed and velocity moment. Results : The results of this study were as follows; 1. In E/E group, the statistically significants were shown on Y speed and velocity moment in the case of normal standing when eye open and X speed and velocity moment in the case of normal standing when eye close(p<0.05). 2. In control group, the statistically significants were not shown on all posture(p>0.05). 3. There was a statistically significant difference on the X speed and velocity moment in the case of normal standing when eye close between control group and E/E group(p<0.05). Conclusion : The above results revealed that hip abductor strengthening exercise using elastic band were partly effective for improving the static balance ability.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.17 no.2
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• pp.11-17
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• 2011

Background: To evaluate the influences of Eye movement program applied to elderly people on static balance. Methods: The subjects consisted of fourteen elderly people. The subjects were divided into two group. The control group (n=7) received no exercise and/or stimulation. The Eye movement program training (E/P) group (n=7) performed balance training using word card and batom. E/P group were accomplished during 4weeks (5 day/week, 60 min/day). All tests were completed before and after experiment. The static balance ability was measured by normal standing when eye open and close on good balance system, respectively. For each case, the experimental data were obtained in 3 item; mean X speed, mean Y speed and velocity moment. Results: The result of this study were as follows: 1. In E/P group, the statistically significants were shown on only mean Y speed in the case of normal standing when eye open (p<.05), but the statistically significants were not shown on mean X, Y speed and velocity moment in the case of normal standing when eye close (p>.05). 2. In control group, the statistically significants were not shown on all posture (p>.05). 3. There was a statistically significant difference on the mean Y speed and velocity moment in the case of normal standing when eye open between control group and E/P group (p<.05). Conclusions: The above results revealed that balance training using Eye movement program were partly effective for improving the static balance ability.

• PNF and Movement
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• v.6 no.1
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• pp.1-12
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• 2008

Purpose : The purpose of this study was to investigate the effects of the combined patterns of PNF(proprioceptive neuromuscular facilitation) on the static balance ability. Methods : The measurements of the static balance ability were completed by 10 subjects for 6 weeks, from October to November 2007. The combined patterns of PNF were carried out by means of self-exercising suggested by Dietz, which were designed as four cases: two positions (standing and quadruped) for both patterns(sprinter and skater), respectively. The exercises were practiced once a day, 3 times a week in same condition. By using the GOOD BALANCE system, assessment of the static balance ability was taken at before and after exercise from 6 positions: normal standing, one leg left and one leg right standing when eye open and close, respectively. For each case, the experimental data was obtained in 3 items: mean X speed, mean Y speed and velocity moment. Results : The results of this study were as follows : 1. There were statistically significant differences of Mean X speed, Mean Y speed and Velocity moment between the before and the after exercise in the case of normal standing when eye open and close(NSEO and NSEC), respectively. 2. There was statistically significant difference of Mean X speed between the before and the after exercise in the case of one leg left standing when eye open(OLLEO). In this case, however, the statistically significant differences were not found in both terms of Mean Y speed and Velocity moment. 3. There were statistically significant differences of Mean X speed and Mean Y speed between the before and the after exercise in the case of one leg left standing when eye close(OLLEC). In this case, however, the statistically significant difference was not found in term of Velocity moment. 4. There were statistically significant differences of Mean X speed, Mean Y speed and Velocity moment between the before and the after exercise in the case of one leg right standing when eye close(OLREC). 5. There was statistically significant difference of Mean X speed between the before and the after exercise in the case of one leg right standing when eye open(OLREO). In this case, however, the statistically significant differences were not found in both terms of Mean Y speed and Velocity moment. 6. There were statistically significant differences of total Mean X speed, total Mean Y speed and total Velocity moment between the before and the after exercise. Conclusions : The above results from this study indicated that the combined patterns of PNF have improved the static balance ability. However the used self-exercise can be applied to normal people, i.e., the exercise is difficult to apply into clinical patients. The further study should be focused at development of various modified forms of the combined patterns of PNF in keeping up the improvement effect of this exercise.