• Physical Therapy Korea
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• v.29 no.2
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• pp.124-130
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• 2022

Background: During postural control, older adults are more dependent on proprioception than are young adults. Ankle proprioception, which plays an important role in maintaining postural balance, decreases with age. Published studies are insufficient to establish a significant age difference in postural sway resulting from the known age-related decrease in ankle proprioception and do not examine various detailed test conditions. Objects: The present study aimed to compare ankle proprioception between older and younger groups along dimensions of position vs. force proprioception and dorsiflexion vs. plantarflexion. The present study also aimed to compare postural sway between young and older women during quiet standing under two sensory conditions. Methods: We recruited seven young women aged 21-24 and seven older women aged 60-63. Ankle proprioception was assessed as the accuracy of the joint position sense (JPS) and the force sense (FS). Postural sway was assessed using center-of-pressure measurements recorded during quiet standing under two sensory positions: eyes open and eyes closed with head tilted back. Results: Older women had lower JPS in dorsiflexion and lower FS in plantarflexion than did younger women. We found no significant age differences in JPS in plantarflexion or in FS in dorsiflexion. We observed a main effect of group on postural sway in two sway parameters out of three. We observed significant differences in JPS with dorsiflexion, and in FS with plantarflexion. Conclusion: Proprioception for ankle plantar flexor decreased more significantly with aging than did that for ankle dorsiflexor, accounting for the impaired postural balance observed in older women.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.4
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• pp.103-113
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• 2019

PURPOSE: The purpose of this study was to determine if virtual reality-based exercise was effective in balance, gait, and falls efficacy in patients with Parkinson's disease (PD). METHODS: Thirty patients with PD were assigned randomly to the experimental (n=15) or control groups (n=15). The experimental group performed virtual reality-based exercise and the control group underwent conventional physical therapy for 30minutes, five times per week for four weeks. A force platform system, the Korean version of the Berg Balance Scale (K-BBS), the six-minute walking test (6MWT), and the Korean Version of the Falls Efficacy Scale (K-FES) were used to evaluate balance, gait, and falls efficacy. Wilcoxon signed-rank test and Mann-Whitney U test were used to examine the within- and between-group differences after training, respectively. RESULTS: Changes in the K-BBS score (p<.001) and fall efficacy (p<.01), following the intervention were significantly greater in the experimental group than in the control group whereas significant group difference were not observed for the anterior-posterior and mediolateral postural sway lengths. The change in the ground reaction force (p<.001) and 6MWT values (p<.05) were significantly greater after intervention in patients in the experimental group than in the control group, whereas a significant group difference was not observed for the step and stride lengths. CONCLUSION: This study indicates that virtual reality-based exercise is an effective intervention for improving balance, gait, and fall efficacy in patients with PD.

• Physical Therapy Korea
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• v.28 no.2
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• pp.154-160
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• 2021

Background: Theoretically, balance is affected by the height of center of mass (COM) during quiet standing. However, no one examined this in humans with variables derived from the center of pressure (COP). Objects: We have conducted balance experiment to measure COP data during quiet standing, in order to examine how the COP measures were affected by the height of COM, vision, floor conditions, and gender. Methods: Twenty individuals stood still with feet together and arms at sides for 30 seconds on a force plate. Trials were acquired with three COM heights: 1% increased or decreased, and not changed, with two vision conditions: eyes closed (EC) and eyes open (EO), and with two floor conditions: unstable (foam pad) and stable (force plate) floor. Outcome variables included the mean distance, root mean square distance, total excursion, mean velocity, and 95% confidence circle area. Results: All outcome variables were associated with the COM height (p < 0.0005), vision (p < 0.0005), and floor condition (p < 0.003). The mean velocity and 95% confidence circle area were 5.7% and 21.8% greater, respectively, in raised COM than in lowered COM (24.6 versus 23.2 mm/s; 1,013.4 versus 832.3 mm²). However, there were no interactions between the COM height and vision condition (p > 0.096), and between the COM height and floor condition (p > 0.183) for all outcome variables. Furthermore, there was no gender difference in all outcome variables (p > 0.186). Conclusion: Balance was affected by the change of COM height induced by a weight belt in human. However, the effect was not affected by vision or floor condition. Our results should inform the design of balance exercise program to improve the outcome of the balance training.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.1
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• pp.22-28
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• 2010

Approximate analysis for a building installed with a friction damper is performed to get insight of its dynamic behavior. Energy balance equation is used to have a closed analytical form solution of dynamic magnification factor(DMF). It is found out that DMF is dependent on friction force ratio and resonance frequency. Approximation of DMF and equivalent damping ratio of a friction damper is proposed with such assumption that the building with a friction damper shows harmonic steady-state response and narrow banded response behavior near resonance frequency. Linear transfer function from input external force to output building displacement is suggested from the simplified DMF equation. Root mean square of a building displacement is derived under earthquake-like random excitation. Finally, design procedure of a friction damper is proposed by finding friction force corresponding to target control ratio. Numerical analysis is carried out to verify the proposed design procedure.

• Journal of the Korean Society of Systems Engineering
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• v.3 no.2
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• pp.25-32
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• 2007

There has been no systematic accumulation in the aircraft weight data even though those are crucial in the full life-cycle weight and balance program of aircraft. Companies, government agencies, and the Korea Air Force have been controling the data separately. The lack of communication between these institutes prevented the mutual use of the data. This study deals with a SE model-based weight and balance program development process for the full life-cycle weight and balance control of aircraft which enabled the efficient and mutual use of the weight data from the various institutes.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.422-425
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• 2002

Position balance control refers to ability that is kept bodily center of gravity under minimum position shake on surface of land. Patients who an injury of brain, a wound of the central nervous system or weakening of leg muscular power is fallen are trend increasing steadily by the car accident body balance function is on an increasing trended. These patients have difficulty in position balance control, receive big restriction walk and life style. This research composed to do body balance function rehabilitation training which elevate leg muscular power using step machine. And expect to become effective rehabilitation training device because measuring bodily pressure center using Force Platform and do so that can confirm training result easily as that is monitor.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.2
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• pp.68-74
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• 2000

A comparative wind tunnel testing of an airplane model was performed at the Korea Aerospace Research Institute Low Speed Wind tunnel(KARI LSWT). The model used for the comparative test was a seaplane model from the Glenn L. Martin Wind(GLM) Tunnel of University of Maryland, U.S.A. The 6-component external balance used in force and moment measurement is pyramidal type, which is a precision device that has strain gauge-type load cell inside of balance and the virtual center of the balance coincides with the tunnel centerline. Image method is adopted to eliminate the tare and interference of the model support, and to correct the flow angularity to the model also. Test results from KARI LSWT were compared with the results from GLM tunnel.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2227-2229
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• 2003

Using the gyro effect, Balance Beam Controller is developed with Samsung Corporation. Balance Beam Controller is possible to control the position of an object in air by controlling the attitude of inner gimbal. But in the unknown load inertia case, even a skilled worker it is not easy to operate a Balance Beam. That is caused by the difficulty to estimate the load inertia. If the amount of the gimbal operation is set excessively with a wrong load estimation, it can often cause accidents. To solve this problem, the control function which is revolving with velocity of the revolution has to be added to developed equipment. In this research, we analyze the characteristics of a Balance Beam(the smaller load inertia, the bigger force of restitution) using the angular velocity sensor, and present constant velocity revolving controller with estimating value of the load using this moving characteristics.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.1-6
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• 2019

Wettability is an important factor to decide solderability of solder, flux, other soldering-related materials and soldering conditions. The wettability also affects the reliability of solder joint. Wetting balance test is a good method for quantitatively measuring wettability between solder and substrate. The wetting balance test is easy to reproduce the wetting experiment and to measure the wetting time and force. And this test provides wetting curve to calculate the surface tension of the molten solder. Development of new solder has been continued in accordance with various and harsh environment in the electronics industry. In this paper, the principle of wetting balance test and recent research issues including nano-composite solder are explained.

• Korean Journal of Applied Biomechanics
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• v.31 no.2
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• pp.119-125
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• 2021

Objective: The purpose of this study was to identify the effect of dynamic postural balance control against tilting platform between golfers and non-golfers. Method: 24 golfers and 26 non-golfers were participated. Eight motion capture cameras, two force plates, and one dynamic balance control platform were used for sensory perception test. It was performed two-way repeated ANOVA with a Bonferroni adjustment at a significant level of a 0.05. Results: Golfers' perception ability was higher than non-golfer according to slope. the CoP, time, angle variables were indicated main effect and interaction effect between golfer and non-golfer. Conclusion: It was known that golfer's proprioception perception ability was higher than non-golfers. Repeated practice such as shots and putting on the uneven ground might improve their balance control.