• Journal of the Korean Society of Physical Medicine
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• v.18 no.2
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• pp.61-70
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• 2023

PURPOSE: This study evaluated an intrinsic foot strengthening exercise method for flat feet by comparing the effects of intrinsic exercises on a stable surface and intrinsic exercises on an unstable surface. METHODS: Twenty-four people with flat feet were divided into two groups. The control group performed short foot exercises and toe towel curl exercises on the stable support surface. The experimental group performed short foot exercises and toe towel curl exercises on an unstable support surface using Aerostep. The navicular drop test, and the static and dynamic balance were measured before and after the intervention. RESULTS: In the experimental and control groups, there was a significant difference in the navicular drop test and static balance before and after the intervention (p < .05). On the other hand, there was no significant difference between the two groups (p > .05). In the dynamic balance, the experimental group showed significant differences in all directions after the intervention (p < .05). The control group showed significant differences in the postero-lateral direction and posteromedial direction (p < .05). In particular, in the forward direction, the experimental group had a more significant change than the control group (p < .05). CONCLUSION: Intrinsic foot muscle strengthening exercises performed on unstable surfaces can be an effective clinical exercise method to improve the dynamic balance ability of people with flat feet.

• Journal of the Korean Society of Physical Medicine
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• v.3 no.1
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• pp.11-20
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• 2008

Purpose : This study was to comparison of EMG of an stable exercise group and unstable exercise group on patients who have had anterior cruciate ligament reconstruction(ACL reconstruction). Methods : The subjects of the study were patients who had no less than 4 weeks after ACL reconstruction and could stand on one leg, and they divided into a control group with 9 patients doing closed kinetic chain exercises on the stable floor and an experimental group with 10 patients doing closed kinetic chain exercises on the unstable floor and in order to compare degrees of the muscle activity of the thigh extensor and flexor was tested each before the exercise, in 3 weeks and 6 weeks after doing exercises by using surface electromyography (Surface EMG). The patients made 3 sets of exercises (10 times per set), each of which consisted of exercises using elastic bands and the squat. Results : There was statistic significance about the vastus medialis muscle. Conclusion : It is thought that the closed-chain exercise could be an exercise program through which patients could enhance the muscle activity of the vastus medialis muscle optionally among the quadriceps muscle and the hamstring muscles which should weaken after ACL reconstruction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.373-384
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• 1989

The motions of a spinning rotor and a fluid enclosed in its cavity are known to have mutual interactions, which change the frequencies of forced vibrations and cause instabilities. These phenomena are of technical importance for fluid-cooled turbines as well as spin-stabilized satellites or rockets containing liquid fuels. In this paper the characteristics of unstable whirling of a rotor containing a partitioned cavity filled with two kinds of liquids are investigated experimentally. It studies the influence of rotational speed and filling ratio of two kinds of liquids on unstable whiring. As a result, it is found that the whirl velocity is approximately equal to, or slightly lower for large masses of trapped fluid than rotor critical speed. In case of a spinning rotor partially filled with two kinds of liquids the boundary surface plays a similar role to the free surface, and cases unstable forward whirl.

• The Journal of Korean Physical Therapy
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• v.33 no.1
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• pp.28-33
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• 2021

Purpose: This study examined the effects of heel raise exercises combined with neuromuscular electrical stimulation (NMES) on the muscle strength and postural control ability of subjects with functional ankle instability (FAI). Methods: Twenty-two subjects with FAI participated in this study. They were assigned randomly to two groups: 11 each in the NMES and the sham-NMES groups. Heel raise exercise was applied, and NMES electrodes were attached to the peroneus longus muscles. The NMES group applied NMES during the heel raise exercise. NMES was applied for 20 minutes during the heel raise exercise. The heel raise exercise was performed four times a week for five weeks. The muscle strength and balance error scoring system (BESS) were measured before and after the intervention. Results: A comparison of before and after the intervention within the groups revealed improved muscle strength in the NMES and Sham-NMES groups, but the BESS was improved under all conditions only in the NMES group. The Sham-NMES group showed no improvement in the unstable support surface. Furthermore, when comparing the amount of change before and after the intervention between the groups, there were significant differences in the total score and unstable support in the BESS and muscle strength. Conclusion: NMES had a positive effect on the functional activities of the functional ankle instability subjects, such as balancing on an unstable support surface during postural control and increasing muscle strength.

• Asian Journal of Atmospheric Environment
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• v.12 no.1
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• pp.47-58
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• 2018

The aim of this work is to investigate the effect of atmospheric stability on near-field pollutant dispersion from rooftop emissions of a single cubic building using computational fluid dynamics (CFD). This paper used the shear stress transport (here after SST) k-${\omega}$ model for predicting the flow and pollutant dispersion around an isolated cubic building. CFD simulations were performed with two emission rates and six atmospheric stability conditions. The results of the simulations were compared with the data from wind tunnel experiments and the result of simulations obtained by previous studies in neutral atmospheric condition. The results indicate that the reattachment length on the roof ($X_R$) obtained by computations show good agreement with the experimental results. However, the reattachment length of the rooftop of the building ($X_F$) is greatly overestimated compared to the findings of wind tunnel test. The result also shows that the general distribution of dimensionless concentration given by SST k-${\omega}$ at the side and leeward wall surfaces is similar to that of the experiment. In unstable conditions, the length of the rooftop cavity was decreased. In stable conditions, the horizontal velocity in the lower part around the building was increased and the vertical velocity around the building was decreased. Stratification increased the horizontal cavity length and width near surface and unstable stratification decreased the horizontal cavity length and width near surface. Maintained stability increases the lateral spread of the plume on the leeward surface. The concentration levels close to the ground's surface under stable conditions were higher than under unstable and neutral conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.598-601
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• 2017

The purpose of this study is to evaluate the effects of Ankle Exercise Program on Muscle Strength and Balance in Middle Aged Woman. Subjects of this study, among the patients who were diagnosed with obesity in the study, for patients total of 8 people have agreed to research. Experimental group 4 people, control group 4 people, was a total of 8 people. Group-specific arbitration method, was applied to Unstable supporting surface exercise program(experimental group) and stable supporting surface exercise program(control group). Each training courses 30 minutes for 6 weeks, examined the changes in Functional Reach Test(FRT) and One Leg Standing(OLST), Dorsi Flexion(DF) and Plantar Flexion(PF) ability to examine a total of 6-week course effectively. The intervention were compared by measuring before and after. There were significant improvements in the subscales of the muscle strength and balance test of those who practiced with the unstable supporting surface exercsie program, while the control group showed no significant changes. Therefore, unstable supporting surface exercsie program is effective in improvement of to improve the muscle strength and balance in woman with obesity.

• Journal of Korean Physical Therapy Science
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• v.25 no.3
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• pp.25-31
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• 2018

Background: The purpose of this study was to find out how changes in knee angles in stable and unstable support surfaces affect the muscle thickness of core muscles. Methods: The subjects of this study were 25 male adult. Each knee angle of 120, 90 and 60 degrees, they were performed bridge exercise on the stabilized surface and on the unstable support surface using TOGU, and measured the muscle thickness of the external and internal oblique muscle and the abdominal muscles through ultrasound images. Results: There was no significant difference between the thickness of the rectus abdominis and the internal oblique muscle depending on the support surface and the knee joint bending angles. However, there was a significant difference between the external oblique muscle and the transverse abdominis muscle by knee joint flexion angle. Conclusion: While the muscle thickness of the core muscle was not significantly affected by each support surface during the bridge exercise, there were significant changes in the core muscle as a result of changes in knee angle.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.47-54
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• 2019

The purpose of this study was to investigate the effect of visual conditions on the static balance of stable and unstable surfaces. Thirty healthy adults participated in this study (13 men, 17 women). Visual conditions were set as vertical, horizontal, and diagonal. It was performed on the pad to measure the balance on the unstable support surface. Using the balance measuring instrument, the General Stability Index, Weight Distribution Index, and Weight Distribution was measured. Paired t-tests were used for ground-based comparisons and one-way ANOVAs were used for comparisons within the same ground. The general stability index showed a significant difference according to the horizontal and vertical line directions on the stable support surface(p<.05). According to the comparison between the grounds, the weight distribution index on the unstable support surface showed a significant difference(p<.05). Weight distribution showed significant differences between the left and right eyes on the support surface with the stable and the unstable horizontal visual condition(p<.05). In static balance training, vertical and diagonal visual direction conditions are predicted to be helpful for training.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.591-594
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• 2003

In this paper, we propose a method to avoidance obstacle in which we assume that obstacle has an unstable limit cycle in the chaos trajectory surface. In order to avoid the obstacle, we assume that all obstacles in the chaos trajectory surface in which has an unstable limit cycle with Van der Pol equation. In this paper show also that computer simulation results are satisfy to avoid obstacle in the chaos trajectory with Chua's circuit equation of one or multi obstacle has an limit cycle with Van der Pol (VDP) efuation and compare to rate of cover in one robot which have random walk and Chua's equation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1692-1699
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• 2004

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. We also show computer simulation results of Arnold equation, Chua's equation, Hyper-chaos equation, Hamilton equation and Lorenz chaos trajectories with one or more Van der Pol obstacles.