• 전기학회논문지P
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• 제58권1호
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• pp.85-89
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• 2009

We investigated the quench characteristics in accordance with increase of turns number of trigger coil and shunt resistance of matrix-type superconducting fault current limiter (SFCL) with $2{\times}3$ array. The matrix-type SFCL consists of the trigger part to apply magnetic field and the current-limiting part to limit fault current. The fault current limiting characteristics according to the increase of magnetic field and applied voltage were nearly same. This is because the application of magnetic field hasn't an affect on total impedance of the SFCL. When turns number of a reactor increased, the voltage difference between two superconducting units in the current-limiting part according was decreased. The resistance difference generated in two superconducting units was also decreased. Therefore, we confirmed that the differences of the critical behaviors between superconducting units were reduced by application of magnetic field. By this results, we could decide the optimum turns number of reactor to apply magnetic field.

• 대한전기학회논문지
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• 제43권7호
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• pp.1050-1060
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• 1994

This paper is a study on the computer simulation of the characteristics of the superconducting fault current limiter. Input variable parameters are apparent power, load resistance value, line resistance value and so on. Initial fault current 2 times larger than the trigger current is required to reduce the switching time of SFCL. The propagation velocity increases abruptly, the transport current is several times larger than the ciritical current. In this paper, the switching time is calculated to be 323$\mu$ sec, and the initial fault current is 19 times larger than the critical current. Because the trigger coils are bifilar winding, they have little impedance in superconducting state. After fault occurred, the limiting coil acts as a superconducting reactor and the trigger coils quench at a critical current. Without the SFCL in the circuit, fault current after the load impedence is shorted might be increased to 1100A. The fault current is, therefore, successfully limited by the superconducting limiting coil to 100A determined by the coil inductance.

• Animal cells and systems
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• 제7권1호
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• pp.81-87
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• 2003

While screening proteins that interact with DnaA protein, the initiator protein for Escherichia coil chromosomal DNA replication, we found a 52-kD sized protein which bound to DnaA protein in a salt-dependent manner. This protein was identified as trigger factor, a ribosome-associated peptidyl-prolyl- cisltrans isomerase with chaperone activity. Trigger factor was overproduced and purified to near homogeneity, and its effect on the function of DnaA protein was examined, Enhanced binding of DnaA protein to DnaA box with no apparent supershift in the gel-shift experiments suggested that trigger factor, by virtue of its chaperone activity, exerts a change on DnaA protein thus increasing its binding affinity for DnaA box.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1816-1818
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• 1997

A triggered sparkp gap switch was fabricater and its high-voltage discharge characteristics were studied. The switch is composed of two main electrodes and one trigger electrode which is placed perpendicular to the main one. Spark gap distance was fixed by 25 mm. This device has been operated without self firing at the pulse repetition frequency from 1 to 20 Hz limited by the charging current, and the hold-off voltage from 10 to 30kV. An IGBT switch and igniter coil (originally used in a car) were adopted for a trigger circuit. In this article preliminary switch characteristics of the spark gap switch are reported with the emphasis on the description of the trigger circuit.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권12호
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• pp.584-590
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• 2002

Crowbar system is usually applied to a pulsed power system in which a capacitor bank is discharged into a load. This provides a free wheeling path for the load current and prevents the capacitor from recharging due to a reverse voltage. Usually diodes have been used as a crowbar switch, but it is not a practical system because the cost of the diodes goes up enormously with increasing the system voltage and current. This paper presents a novel protection scheme of a charging and discharging system of a 300 kJ capacitor bank using a low-cost crowbar system which consists of a crowbar switch and resistors. Triggered vacuum switch(TVS) was used for a crowbar switch, and Rogowski coil was used to determine a trigger time of TVS. When this crowbar system is applied to our pulsed power system which consists of capacitor bank($123muF$), inductor() for forming a pulse, load resistor$(100 m\Omega)$, and a closing switch, instantaneous reversal voltage of capacitor bank could be limited less than 1.8 ㎸ until capacitor bank was charred to 17 ㎸.

• 대한전기학회논문지
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• 제45권1호
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• pp.14-17
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• 1996

We analyzed the characteristics of a power system with superconducting fault current limiter and showed the possibility of the application of a superconducting fault current limiter to a real power system through manufacturing of and experiment about 220Vrms/100Apeak class superconducting fault current limiter. We experimentally confirmed that the overvoltage of superconducting fault current limiter increased as the rate of current sharing to the limiting coil grew. The fault current could be limited within a few milliseconds when it was applied to a power system in series. Therefore, we could confirm that superconducting fault current limiter was effective in protection of a substation or power plant at short-circuit fault. (author). 7 refs., 7 figs., 2 tabs.

• 전기전자학회논문지
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• 제16권3호
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• pp.217-223
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• 2012

본 논문은 트리거 시간을 조절하여 펄스 성형이 가능한 150 MW 펄스 파워 시스템의 설계와 동작특성을 알아보았다. 이 시스템은 2개의 커패시터 뱅크 모듈로 구성되어 있고, 각 커패시터 뱅크 모듈은 병렬로 연결되어 있다. 그리고 커패시터 뱅크 모듈은 메인스위치, 커패시터, 에너지 덤프회로, 크로바 회로, 펄스 성형 인덕터로 구성되어 있다. 또한 이 시스템의 모듈 선택과 트리거 시간은 트리거 제어부에서 조정된다. Pspice 시뮬레이션은 실험회로의 결과를 예측하고, 시스템의 구성품의 파라미터를 결정하기 위한 것으로 사용하였다. 실험 결과, 시뮬레이션은 실험결과와 잘 일치하였다. 출력 전류의 펄스폭은 커패시터 뱅크 모듈에서의 순간적 점화 시간 제어로 300~650 us의 펄스폭이 형성되었다. 그리고 최대 전류값은 2개의 커패시터 뱅크 모듈이 동시에 트리거 되었을 때 약 40 kA 정도이다. 이 150 MW 펄스 파워 시스템은 파암 전원, Rail Gun, Coil Gun, 나노분말 제조, HPM 등과 같은 대전류 펄스 파워 시스템에 적용할 수 있다.

• 대한전자공학회논문지
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• 제13권2호
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• pp.5-13
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• 1976

개소린 엔진 자동차의 연료절차, 공해감소, 보수경감을 목적으로 용량방전점화장치(CDI)를 해석적 및 실험적으로 설계하는 과정을 기술하였다. 특히 방전시스템에 대한 간단한 모델을 사용함으로써 점화코일의 입출력전압, 전류를 계산하였다. 그 결과 실험치와 비교하였으며 이로 부터 최적점화조건을 만족하기 위한 방전용량, SCR 및 다이오드의 정격과 DC-DC 콘버터의 소요출력전압을 결정하였다. 또 과도한 dv/dt 및 di/dt에 대한 SCR의 보호회로를 해석하고 그 결과를 관측된 결과를 관측된 결과와 비교하였는데 이로써 SCR선택과 보호회로 및 트리거 회로 설계가 용이하게 된다. 더우기 DC-DC콘버터의 거동에 대한 실험적 결과를 해석하므로써 콘버터 설계를 간이화하였다. 실용적인 CDI장치를 시작하였으며 이것은 실험실 및 노상 시험에서 만족할만한 성능을 나타냈다. 그 시험결과도 아울러 보고한다. An analytical and experimental design procedure is described for the Capacitor Discharge Ignition (CDI) System with a view to fuel saving ann reduction of gas exhaustion and maintenance need. Specifically, the input and output voltage and current of a given ignition coil were calculated by using a simplified circuit model for the discharging system. The results were compared with the experimental results, from which ratings of the charging capacitor, the SCR and the diodes and the required output valtage of the DC·DC converter were determined so as to satisfy the optimum ignition conditions. Protection circuits for excessive dv/dt and di/dt for the SCR were also analyzed and the results were compared with the observed results, which facilitate selection of the SCR and design of the protection circuit and the trigger circuit. Also, design of the DC·DC converter was simplified based on the analysis and experimental results of the behavior of the converter, An experimental, yet practical CDI system was built, which showed satisfactory performance in the laboratory and field tests. The results were also reported.

• 로봇학회논문지
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• 제8권2호
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• pp.136-142
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• 2013

In nature, many small insects are using jumping as a survival strategy. Among them, fleas jump in a unique method. They use an elastomer, 'Resilin', an extensor muscle and a trigger muscle. By contracting the extensor muscle, the elastic energy, that makes a flea to jump, is stored in the resilin. After storing energy, the trigger muscle begins contracting and pulling the extensor muscle. When the extensor muscle crosses the rotational joint, direction of torque generated from the extensor muscle reverses, 'torque reversal mechanism'. Simultaneously, the elastic energy stored in the resilin releases rapidly and is converted into the kinetic energy. It makes a flea to jump 150 times its body length. In this paper, miniaturized jumping robot using flea-inspired catapult mechanism is presented. This mechanism is based on the 4-bar linkage and the reversal joint and is actuated by Shape Memory Alloy (SMA) coiled springs describing the flea's muscle. The robot prototype is fabricated by SCM process using glass fiber prepregs and a sheet of polyimide film. The prototype is 20mm link length, 34mm width and 2.0g weight and can jump 103cm.

• 대한디지털의료영상학회논문지
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• 제10권1호
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• pp.45-50
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• 2008

Recently, MR Cholangiography used mainly bu controlling of patient's breathing. There is breathing hold techniques to get images within shopt time and gating technique adjusted to respiration cycle for high resolution image. In this study, the aim of this experiment is to know on clinical usefulness compared with PACE and RTG thchniques. This study's period is from 2006 in November to 2007 in January. A total of 21 patients investigated at MAGNETOM Sonata 1.5T (SIEMENS Erlangen) with use of 12ch body coil. MR acquisition protocol used 3D turbo spin echo coronal sequence. Scan parameters applied to potimal setting in use as gating techniques, respectively. Analysis of consuming timing evaluated with rapidness. As analysis of quantity, the common bile duct, gall bladder measured in signal intensities, then these data were calculated by signal to noise ratio and contrast to noise ratio. Qualitative analysis, experienced 2radiologists and 3 RTs were evaluated into 3groups about artifact, accuracy of lesions, sharpness of the common bile duct or gall bladder. As a result of analysis, when compared to PACE, consuming time of the RTG took less than PACE, On both CNRs and SNRs, PACE technique was slightly high values than RTG(p<0.05). Qualitative analysis' results, discrimination of lesions in the common bile duct, gall bladder get a significance level in both RTG and PACE techniques but presence's artifact of breathing and pulsation highly demonstrate in PACE techniques. In conclusion, both PACE and RTG methods at MRCP provided prominently clinical information for the common bile duct, gall bladder. If machines have not limitation with performance, induction of breathing holding also will help getting diagnistic quality.