• 한국광학회지
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• 제14권4호
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• pp.399-405
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• 2003

FD10 유리를 이용한 클램프형 광전류 센서를 제작하였다. 대칭형 구조로 이루어진 2조각의 FD10유리를 이용하여 제작하였으며, 센서헤드 내부에서 반사시에 위상차가 발생하는 것을 방지하기 위해 정확히 임계각으로 광이 진행하도록 구조를 설계하였다. 제작한 광-전류 변류기 헤드를 이용하여, 0-1,000 AT 까지의 전류를 측정하고, 빛의 입사각에 따른 광의 손실, 입사광의 편광회전에 따른 광출력변화, 온도에 따른 출력의 변화 및 장시간 전류 측정 등에 대한 실험결과를 제시하고 이에 대한 분석을 통해 제작된 광전류 변류기 헤드의 전류계로서의 가능성을 입증하였다.

• 동의생리병리학회지
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• 제27권1호
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• pp.112-117
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• 2013

We studied the modulation of pacemaker activities by Samchulkunbi-tang (SCKB) in cultured interstitial cells of Cajal (ICC) from murine small intestine with the whole-cell patch-clamp technique. Externally applied SCKB produced membrane depolarization in the current-clamp mode. The pretreatment with $Ca^{2+}$-free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker potentials and suppressed the SCKB-induced action. The application of flufenamic acid (a nonselective cation channel blocker) abolished the generation of pacemaker potentials by SCKB. However, the application of niflumic acid (a chloride channel blocker) did not inhibit the generation of pacemaker potentials by SCKB. In addition, the membrane depolarizations were inhibited by not only GDP-${\beta}$-S, which permanently binds G-binding proteins, but also U-73122, an active phospholipase C inhibitor. These results suggest that SCKB modulates the pacemaker activities by nonselective cation channels and external $Ca^{2+}$ influx and internal $Ca^{2+}$ release via G-protein and phospholipase C-dependent mechanism. Therefore, the ICC are targets for SCKB and their interaction can affect intestinal motility.

• 에너지공학
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• 제12권1호
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• pp.23-28
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• 2003

본 논문에서는 ANSYS 소프트웨어를 사용하여 회전시료조사대의 진동특성을 공기중 및 수중에서 평가하였다. 수중에서 진동해석에서 사용된 추가질량은 Blevins가 제시한 수식을 이용하여 계산하였다. 본 논문에서 제시한 결과의 타당성을 확인하기 위하여 구해진 결과는 이론적인 식을 사용해 구한 결과와 비교하였다. 유체의 추가질량 효과 때문에 회전시료조사대의 고유진동수는 공기 중에서 보다 수중에서 낮아짐을 확인할 수 있었다. 그리고 회전시료조사대의 고정에 필요한 클램프를 설계하기 위하여 클램프의 압력에 대한 회전시료조사대의 등가응력 및 변위를 계산하였다.

• 전력전자학회논문지
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• 제16권2호
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• pp.105-113
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• 2011

태양광 발전 시스템이 대용량화됨에 따라 태양전지 어레이 구성 시 부정합(mismatch) 문제가 대두되는 가운데, 태양전지 모듈을 직접 계통에 연계하는 AC 모듈형 태양광 모듈 집적형 전력변환장치(PV-MIC)에 관한 연구가 지속되고 있다. PV-MIC는 수명 및 고효율이 가장 큰 문제이며 이 문제를 해결하기 위해서 본 논문에서는 ZVS 동작을 통하여 스위칭 손실을 저감시키고 입력전류 리플감소를 통하여 입력 커패시턴스를 저감할 수 있는 능동 클램프 전류원 하프 브릿지 컨버터를 적용한 PV-MIC를 제안하고, 이에 관한 제어분담 및 설계에 대하여 고찰한다.

• The Korean Journal of Physiology and Pharmacology
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• 제4권4호
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• pp.333-338
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• 2000

We have examined whether bile acids can affect the electrical and mechanical activities of circular smooth muscle of canine colon and ileum, using isometric tension measurement or patch clamp technique. It was found that a dilution of canine bile $(0.03{\sim}2%\;by\;volume)$ enhanced or inhibited the amplitude of spontaneous contractions. An individual component of bile, deoxycholic acid (DCA) enhanced the frequency and amplitude of the spontaneous contractile activity at $10^{-6}\;M,$ while DCA at $10^{-4}\;M$ inhibited the contraction. Similarly, the response to cholic acid was excitatory at $10^{-5}\;M$ and inhibitory at $3{\times}10^{-4}\;M.$ Taurocholic acid at $10^{-4}\;M$ enhanced the amplitude of muscle contraction. Electrically, canine bile at 1% reversibly depolarized the colonic myocytes under current clamp mode. Bile acids also elicited non-selective cation currents under voltage clamp studies, where $K^+$ currents were blocked and the $Cl^-$ gradient was adjusted so that $E_{Cl}^-$ was equal to -70 mV, a holding potential. The non-selective cation current might explain the depolarization caused by bile acids in intact muscles. Furthermore, the bile acid regulation of electrical and mechanical activities of intestinal smooth muscle may explain some of the pathophysiological conditions accompanying defects in bile reabsorption.

• 전력전자학회논문지
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• 제10권3호
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• pp.302-311
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• 2005

본 논문에서는 액티브 클램프 포워드컨버터 2차 측에 탭-인덕터와 스너버 커페시터, 두 개의 다이오드로 구성된 무손실 스너버를 적용한 개선된 액티브클램프 포워드컨버터를 제안하였고, 종래의 컨버터와 비교하여 제안된 컨버터가 보다 적은 자화전류조건에서도 영전압 스위칭(ZVS)이 가능함을 보였다. 제안된 컨버터의 동작원리 및 모드를 분석하였고, 300W출력용량의 컨버터 시제품을 제작 실험하여 제안된 컨버터의 효율특성이 개선됨을 보였다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1066-1074
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• 2015

This paper presents the reverse recovery characteristic according to the change of switching states when Si diode and SiC diode are used as clamp diode and proposes a method to minimize the switching loss containing the reverse recovery loss in the neutral-point-clamped inverter at low modulation index. The previous papers introduce many multiple circuits replacing Si diode with SiC diode to reduce the switching loss. In the neutral-point-clamped inverter, the switching loss can be also reduced by replacing device in the clamp diode. However, the switching loss in IGBT is large and the reduced switching loss cannot be still neglected. It is expected that the reverse recovery effect can be infrequent and the switching loss can be considerably reduced by the proposed method. Therefore, it is also possible to operate the inverter at the higher frequency with the better system efficiency and reduce the volume, weight and cost of filters and heatsink. The effectiveness of the proposed method is verified by numerical analysis and experiment results.

• Smart Structures and Systems
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• 제13권4호
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• pp.567-585
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• 2014

The piezoelectric transverse $d_{15}$ shear sensing mechanism is firstly assessed experimentally for a cantilever smart sandwich plate made of a piezoceramic axially poled patched core and glass fiber reinforced polymer composite faces. Different electrical connections are tested for the assessment of the sensor performance under a varying amplitude harmonic (at 24 Hz) force. Also, the dynamic response of the smart sandwich composite structure is monitored using different acquisition devices. The obtained experimentally sensed voltages are compared to those resulting from the benchmark three-dimensional piezoelectric coupled finite element simulations using a commercial code where realistic features, like equipotential conditions on the patches' electrodes and mechanical updating of the clamp, are considered. Numerically, it is found that the stiffness of the clamp, which is much softer than the ideal one, has an enormous influence on the sensed voltage of its adjacent patch; therefore, sensing with the patch on the free side would be more advantageous for a cantilever configuration. Apart from confirming the latter result, the plate benchmark experimental assessment showed that the parallel connection of its two oppositely poled patches has a moderate performance but better than the clamp side patch acting as an individual sensor.

• 한국농공학회지
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• 제43권6호
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• pp.113-119
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• 2001

Experiments on the yield strength of pipe connectors made of metal wire, joint pins, pole pipes, multi span insertion joints, and T-clamp joints used in pipe houses were conducted. The strength of connections of a pipe connector made of metal wire was adequate but it had a big difference according to loading direction. Therefore as it is installed, its direction should be taken into consideration. The collapse load of pipes connected with a joint pin was lower than that of single pipes. In the part of frame member at which the great bending moment occurs, the use of joint pin should be avoided. Also experimental results showed that pole pipes for use in a part of frame buried under the ground were safe, and the strength of multi span insertion joints should be increased. The resistant moment of T-clamp was about 13.7% of a single pipe. In case that the external forces acting on left and right rafter are different. a unsymmetrical rotational force is produced at the multi span joint. If it is expected that the actual bending moment on the multi span joint is larger than resistant moment of T-clamp, a reinforcement to safely resist the rotational force is required.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.8-17
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• 2010

In this paper, a fault tolerant control against sensor faults of electric parking brake (EPB) is proposed. Fault tolerant control method of EPB system is strongly demanded since sensor faults can endanger a driver's safety. In this paper, a clamp force estimation method is presented using motor's armature current and angular velocity. Clamp force estimation method is applied for fault detection method with parity equations. The goal of the detection method is to detect and identify faults in encoder, current sensor, force sensor, and parking cable. And a switching logic for fault tolerant control against the three sensor faults is suggested. Experimental results show that the proposed force estimation method satisfies the specifications of EPB system. The effectiveness of the fault detection method is validated with experimental results. Although a single sensor fault happens, EPB system with the proposed fault detection method does not develop into a failure on subsystem or system level.