• 설비공학논문집
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• 제10권5호
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• pp.535-549
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• 1998

A numerical study for performance analysis of a counterflow type forced draft tower and natural draft cooling tower has been performed based on the method using the finite volume method with non-orthogonal body fitted and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy balance, moisture fraction balance, water enthalpy balance, and water mass balance equations are solved with Navier-Stoke’s equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study, The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also peformed.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권7호
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• pp.363-368
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• 1999

The parallel operation system of multiple uninterruptible power supplies(UPSs) is used to increase power capacity of the system or to secure higher reliability at critical loads. In the parallel operation of the two UPSs, the load-sharing control to maintain the current balance between them is a key technique. Because a UPS has low output impedance and quick response characteristics, in case of an unbalanced load inverter output current changes very rapidly and thereby can instantaneously reach an overload condition. In this study, high precise load-sharing controller is proposed and implemented for the parallel operation system of two UPSs with low impedance characteristics and this controller controls the frequency and the voltage to minimize the active power component and the reactive power component which are gotten from the current difference between two UPSs. And then a good performance of the proposed method is verified by experiments in the parallel operation system with two 40KVA UPSs.

• 대한통합의학회지
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• 제3권3호
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• pp.49-57
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• 2015

Purpose : The purpose of this study was to identify whether static and dynamic balance in young men were influenced by the different height of insoles in their shoes. Methods : Eighteen healthy young men (mean $20.61{\pm}1.38years$) were recruited for this study. The subjects' static and dynamic balance were assessed while wearing three different height' insoles (0cm, 2cm, 3cm) in their tennis shoes. Anterioposterior (AP) and mediolateral (ML) sway velocity was measured for 20 seconds using a force plate (Good balance system, Finland) under four conditions including normal standing with eyes open and with eyes closed, and tandem standing with eyes open and with eyes closed. The Functional Reach Test (FRT) and Timed Up & Go (TUG) were also performed for each subject under each condition. Results : 1) ML and AP sway velocities in young men were significantly different according to the height of the insole in normal standing with eyes open and eyes closed. 2) ML and AP sway velocities in young men were not different according to the height of the insole in tandem standing with eyes open. 3) ML sway velocities in young men were significantly different according to the height of the insole in tandem standing with eyes closed, whereas AP sway velocities did not differ by height of the insole in tandem standing with eyes closed. 4) FRT scores in young men were significantly different according to the height of the insole. 5) TUG scores in young men were not significantly different according to the height of the insole. Conclusions : This study's results indicate that the static and dynamic balance in young men can be influenced by shoe insole height.

• 제어로봇시스템학회논문지
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• 제3권6호
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• pp.639-643
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• 1997

This paper presents how nonlinear PID control algorithms can be applied on chemical processes for a more stable operation and perfect automation. A pass balance controller is designed to balance the exiting temperatures of a heater and a heat exchange network. The proposed controller has gain-varying integral action and deals with the operational constraints in an efficient manner. Also, the use of a PID gap controller is proposed to maximize energy saving and operation stability and to minimize operator intervention in operation of air fan coolers. The proposed controller adjusts the opening of a louver automatically in such a way that it keeps the air fan pitch position within the desired range. All these nonlinear PID controllers have been implemented on the distributed control system (DCS) for good reliability and operability. Operator acceptance was very high and the implemented controllers have shown good performance and high service factor still now on. The proposed methodology can be directly applied to similar processes without any modification.

• The Journal of Korean Physical Therapy
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• 제24권2호
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• pp.143-150
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• 2012

Purpose: This study was intended to discover the effect of the turning training on figure of 8 tract on stroke patients' static and dynamic balance, as well as walking. Methods: A total of 42 stroke patients participated in this study. The training group was trained on the figure of 8 tract, while the control group was trained on the straight path for 30 minutes per day, for 4 weeks. Berg balance scale was used to measure the balance of the patients, before and after the training, and Good balance system was used to measure the sway speed and the distance of COG while standing. To measure the ability of walking, TUG and FSST were also used. Results: There were significant increases in the average score of Berg balance scale, in both groups after the training, and also significant difference between both groups were observed. The training group showed significant differences in the static balance ability, as well as anteroposterior and mediolateral sway speed. Further, there were significant increases in the dynamic balance ability, COP total distance, and TUG in both groups. The results showed more differences in comparing the control group with that of the training group. In FSST, there was no change in the control group, but there was a significant increase in the training group. Conclusion: Turning training on figure of 8 tract in stroke patients significantly increased the static and dynamic balance and walking ability. Based on the results, it can be seen that the training on the figure of 8 tract can influence the ability of balance and walking, which can lead to appropriate reactions to the change of environment and various tasks. Thus, it is assumed that turning training on figure of 8 tract as a means of improving the condition of stroke patients can be a meaningful program.

• 대한인간공학회지
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• 제32권1호
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• pp.145-152
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• 2013

Objective: The aim of this study is to develop an ergonomic office chair that has an alarm function for the unbalanced sitting postures. Background: Contrary to expectation, it is reported that office workers sit on their chairs much more in unbalanced postures during daily work. Even though an office worker uses an ergonomically good-designed chair and begins their work in a good sitting posture, his/her posture is likely to shift to the unbalanced bad posture. Therefore, a posture alarm system would be very helpful in keeping office workers' good postures. Method: We developed a prototype chair with four load cells under a seat pan and one load cell beneath a backrest. Through some experiments, we set the criteria for unbalanced bad postures then implemented the criteria into the alarm system of the prototype chair. The chair called e-BASE chair could detect unbalance postures and show alarms for chair users. We also enhanced back support by developing a step-wised folding backrest. Results: The e-BASE chair showed better performance in interface pressure distributions and balanced posture ratio in VDT work. Conclusion: The ergonomic chair with posture alarm function(e-BASE chair) was developed. It showed better performance in seat pressure distribution and in keeping good posture during office work. Application: The posture alarm system and folding backrest can be applied to the new models of office chair.

• The Journal of Korean Physical Therapy
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• 제24권4호
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• pp.253-261
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• 2012

Purpose: In this study, the following experiment was conducted to see how to apply the sprinter pattern in proprioceptive neuromuscular facilitation (PNF) and functional weight bearing exercise affected balance capabilities and weight bearing among chronic stroke patients. Methods: The subjects included 27 subjects who had been diagnosed with hemiplegia due to stroke. A total of 12 sessions was held, 3 sessions a week over 4 weeks, were provided to the groups. The control group received general rehabilitation program, and the experimental group performed sprinter pattern in PNF or functional weight bearing exercise. The weight bearing capability and static balance capability test was implemented by using Good-Balance System and Frailty and Injuries Cooperative Studies of Intervention Techniques, while the dynamic balance capability test was carried out by using Four Square Step Test and Timed "Up and Go". Results: The paretic/nonparetic side weight bearing by application of each exercise showed that there were no significant differences in variation among each groups on before exercise, after exercise, 2 weeks after exercise. Static balance test by application of each exercise showed that there were significant differences after exercise and 2 weeks after exercise. Dynamic balance test by application of each exercise showed that there were significant differences after exercise and 2 weeks after exercise. Conclusion: To put the results together, the application of sprinter pattern and functional weight bearing exercise was effective in improving static and dynamic balance capabilities. Therefore, these exercises are helpful to improve balance in patients with stroke.

• 한국항공우주학회지
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• 제37권3호
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• pp.301-306
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• 2009

본 연구에서는 축소형 로터 실험 장치에서 로터 회전면에 수직으로 작용하는 추력(Fz)과 평행으로 작용하는 2축 모멘트(Mx, My)를 측정할 수 있는 3분력 Rotating Balance를 설계, 제작하고 성능실험을 통하여 검증하였다. Rotating Balance에 장착된 스트레인게이지의 미세신호는 로터와 함께 회전하는 신호증폭기를 거쳐 증폭되어 slip ring을 통하여 데이터 취득장치로 전달되어진다. 정적 보정법을 통하여 얻어진 보정행렬식의 적합성 여부를 판단하기 위하여 기존에 개발된 reaction type balance를 사용하여, 로터가 회전시 발생하는 추력을 비교함으로서 측정 정밀도를 확인하였다. 또한, Rotating Balance의 확장 불확도는 A형 불확도와 B형 불확도를 계산하였고, 계산 결과로 부터 $2.82\times10^{-1}$의 값을 얻음으로서 신뢰성을 확인하였다.

• 한국전문물리치료학회지
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• 제25권3호
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• pp.27-38
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• 2018

Background: At present time, smartphones have become very popular and powerful devices, and smartphone applications with the good validity have been designed to assess human balance ability. Objects: The purpose of this study is to evaluate the feasibility of smartphone acceleration in the assessment of postural control ability for six different conditions. Methods: Twenty healthy college-aged individuals volunteered. Static balance ability was measured twice with one-day interval using smartphone application and 3D motion capture system under the six different conditions. Results: Dominant frequencies for each test condition did not show significant differences except for two conditions. The intra-rater correlation coefficient between the first and second tests showed high correlations in six conditions(r>.70, p<.05). Smartphone acceleration and the acceleration calculated from the 3D marker position data showed high correlation coefficient(r>.80, p<.001). Conclusion: Acceleration recorded from a smartphone could be useful assessment variables for balance test in the clinical field.

• 대한정형도수물리치료학회지
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• 제23권1호
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• pp.23-30
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• 2017

Purpose: The purpose of this study was to investigate the effect of transverse abdominis ratio and balance ability during bridge exercises on different support surface. Methods: The subjects were 20 students at G University. Ultrasound equipment was used to measure the transverse abdominisratio and the computerized balance measurement equipment was used to measure the balance ability before and after bridge exercises on different support surface. Results: Transverse abdominis ratio change between the groups was a significant difference only in the unstable support surface training group (p<.05). Normal standing eye close balance ability change between the groups was significantly different only in the unstable support surface training group (p<.05). The changes in the transverse abdominis ratio after 7 days of exercise and 14 days after exercise were significantly different between the groups (p<.05). Normal standing eye close balance ability showed a significant difference at 7 days after exercise and 14 days after exercise (p<.05). Conclusions: It is more effective to balance ability and ratio of the transverse abdominis when bridge exercises on an unstable support surface than to perform bridge exercises on a stable support surface. Therefore, we propose an effective program for patients with instability of the lumbar in clinical practice. bridge exercises on different support surface.