• 한국전문물리치료학회지
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• 제7권2호
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• pp.1-19
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• 2000

Decreased equilibrium in standing and walking is a common problem associated with hemiparesis secondary to cerebral vascular accident. In patients with hemiplegia, postural sway is increased and often displaced laterally over the non-affected leg, reflecting asymmetry in lower extremity weight bearing during standing balance. Human balance is a complex motor control task, requiring integration of sensory information, neural processing, and biomechanical factors. Limits of stability (LOS) is a one of the biomechanical factors. The purposes of this study were to establish the influence of asymmetrical weight-bearing on the LOS of independent ambulatory hemiparetic patients. The subjects of this study were 29 hemiparetic patients (18 males, 11 females) being treated as admitted or out patients at Young-Nam University Hospital and Taegu Catholic University Hospital, all of whom agreed to participate in the study. Participants were asked to lean and displace their center of gravity (COG) as far as possible in directions to the sides and front of the body. The LOS and weight-bearing ratio were measured with a Balance Performance Monitor (BPM) Dataprint Software Version 5.3. In order to assure the statistical significance of the results, the independent t-test and a Pearson's correlation were applied at the .05 and .01 level of significance. The results of this study were as follows: 1) There were statistically significant differences in anteroposterior LOS according to the cause of brain demage (p<.01). 2) There were statistically significant differences in mediolateral LOS according to the hemiparetic side (p<.05). 3) There were statistically significant differences in anteroposterior and mediolateral LOS according to the brain operation (p<.01). 4) The mediolateral LOS significantly correlated with weight-bearing ratio (p<.01).

• 전력전자학회논문지
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• 제6권6호
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• pp.514-524
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• 2001

종전의 평균전력이론은 3상 불평형과 같은 전원전압 조건에 따라 능동전력필터의 보상기준전류가 결정적으로 영향을 받는 문제점이 있다. 이와 같은 불평형된 능동전력 필터의 보상전류는 결과적으로 불평형이 되는 원인이 된다. 본 연구에서는 불평형 전원 하에서도 유효전력과 기본파 무효전력의 동기 검출법에 입각하여 비선형 부하전류의 유효성분과 기본파 무효성분 그리고 왜형 성분을 각각 독립적으로 분해가 가능한 평균전력 이론을 제시하였다. 제안된 이론은 간단한 평균전력 이론을 기반으로 하고 잇기 때문에 우선 이해사기 쉽고 구현이 간단하다는 장점이 있다. 본 연구 에서는 고속의 DSP(digital signal processor)에 의하여 이와 같은 문제을 어느정 도 해결할 수있었다. 제안된 방법의 타당성을 입증하기 위해서 TMS320C31-DSP기반의 전력분석 시스템을 제작하였다. b상 전압이 15% 불평형된 3상 3전 전원하에서 시뮬레이션 및 실험을 수행한 결과 종전의 방법에 비하여 제안된 알고리즘의 유용성을 입증할수 있었다.

• 한국응용과학기술학회지
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• 제16권3호
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• pp.249-254
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• 1999

The N-docosyl N'-methyl viologen-$(TCNQ)_2$, (DMVT) was synthesized. We investigated the ${\pi}-A$ isotherm of DMVT to find the optimal deposition condition. Temperature-dependent current-voltage characteristics of the DMVT LB films shows that there is an increase in conductivity at 330K or so. The in-plane electrical conductivity at room temperature is in the range of $10^{-7}{\sim}10^{-6}S/cm$. From the plot of logarithmic conductivity as a function of reciprocal temperature, two types of activation energies, 0.04eV and 0.73eV, were obtained depending on the temperature range. The Ohmic behaviour was observed below 0.6V and the Schottky effect was confirmed at $2.5{\sim}6V$, when the I-V characteristics was measured with Al/LB film/Al structure. I-V measurement for Al/LB film/ITO structure showed the asymmetrical I-V relationship, which resulted from the rectification property.

• Journal of Magnetics
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• 제19권1호
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• pp.90-100
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• 2014

Position estimation that uses only active phase voltage and current is presented, to perform high accuracy position sensorless control of a SRM drive. By extracting the amplitude of the first switching harmonic terms of phase voltage and current for a PWM period through Fast Fourier Transform (FFT), the flux-linkage and position are estimated without external hardware circuitry, such as a modulator and demodulator, which result in increased cost, as well as large position estimation error, produced when the motional back EMF is ignored near zero speed. A two-phase SRM drive system, consisting of an asymmetrical converter and a conventional closed-loop PI current controller, is utilized to validate the performance of the proposed position estimation scheme in comprehensive operating conditions. It is shown that the estimated values very closely track the actual values, in dynamic simulations and experiments.

• 한국응용과학기술학회지
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• 제23권3호
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• pp.177-184
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• 2006

Because of the difference in the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenol such as monosubstituted hydroquinone was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid and phenylhydroquinone by the reaction using diphenyl chlorophosphate in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and the addition time of hydroquinone, and by modifying it through an association of hydroquinone with LiCl.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.119-123
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• 2001

In this paper, a DCM operated boost integrated single-stage forward-flyback converter is proposed. This proposed converter has high power factor, low harmonic distortion, and tight output regulation. To increase efficiency, zero voltage switching with asymmetrical control is used. This converter also give low voltage stress in switch and this results in low conduction loss with low turn-on resistance.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.143-145
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• 2009

The method for the current equalization of the rectifier diodes in LLC resonant converter is proposed. The method decreases the current difference between the rectifier diodes using the auxiliary winding of the transformer and asymmetrical pulse width modulation (APWM). The analytical reason of the current unbalance is investigated and the operation principle of the proposed method and APWM control loop are explained. The performance of the proposed method was verified on a 480-W, 400-V/24-V dc/dc converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.215_216
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• 2009

This paper presents a asymmetry fault current reduction scheme with recloser operation during transient period. The principle of asymmetry current nature is reviewed and asymmetry components reduction with recloser operation is explained. Throughout the simulation, results verifies the proposed scheme for recloser operation and its effectiveness.

• 한국산업융합학회 논문집
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• 제5권2호
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• pp.147-152
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• 2002

Because of the difference of the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenols such as monosubstituted hydroquinones was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid, and phenylhydroquinone by the reaction using p-Toluenesulfonylchloride in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and addition time of the hydroquinone, and by modifying it through an association of the hydroquinones with DMF.

• Advances in concrete construction
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• 제1권2호
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• pp.121-136
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• 2013

Tension tests were carried out to investigate the effect of the corrosion pattern on the ductility of tension bars extracted from a 26-year-old corroded reinforced concrete beam. The tensile behavior of corroded bars with different corrosion patterns was examined carefully, as were two non-corroded bars extracted from a 26-year-old control beam. The results show that corrosion leads to an increase in the ratio of the ultimate strength over the yield strength, but reduces the ultimate strain at maximum force of the reinforcement. Both the corrosion pattern and the corrosion intensity play an important role in the ductile properties. The asymmetrical distribution of the corrosion around the surface is a decisive factor, which can influence the ultimate strain at maximum force more seriously.