• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.264-267
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• 2004

Recently the pulsed power systems have been widely used in many fields such as E/P(Electrostatic Precipitator), DeNOx/DeSOx power systems, ozone generators and power sources of the laser beam. In this paper, we studied various electrical characteristics for arc suppression of line-to-line electrodes in air and removal of the metaloxide using our pulsed power system. To obtain high efficiency of the pulsed power system, we repeatedly experimented and tested their characteristics. by adjusting electrode length of the load. As a result, when the value of the electrode length and pulse repetition rate were changed at the load, the value of the arc voltage changed at the electrode load. In conclusion, we controlled arc voltage of the load by ,changing electrode length and pulse repetition rate. Also. we stydied removal area of the metaloxide using area discharge according to pulse repetition rate.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.24-30
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• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.115-119
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• 2015

The power relay can be easily controlled with high voltage and current through the contacts. For this reason, has become widely used range in a variety of applications. In this study, we measured the contact resistance between the bouncing phenomenon of contact due to the change of load. The results of the experiment, the contact resistance increases with the deterioration of the contact, it is possible to predict the life of the relay contacts through the contact resistance. And relay bounce duration time have occurred in 3.5 ms or less. In addition, it is possible to use the results to design an arc suppression circuit device.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.69-73
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• 2005

The arc dispersion and contacts characteristics were analyzed according to switching off Residual Current Protective Device(RCD) switch. Arc dispersion process was taken by high speed imaging system at a rate of 10,000 frames per second. When RCD was switched from on to off, art was observed and it took about 2.3[ms] from the generation of arc to the extinction of arc. When RCD was switched from off to on, arc was not observed. We repeated switching on and off 1000, 3000 and 6000 times. After repetition, the surface characteristics of contacts were taken by stereo microscope and Scanning Electron Microscope(SEM). From the scattering patterns analysis of arc and the analysis of deteriorated contacts, it could be applicable to the research of electric fire and arc suppression.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.227-230
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• 2003

Silicone rubber has very excellent chemical stability and hydrophobicity. A hydrophobic surface can prevent the formation of continuous water films on the surface in wet and heavily contaminated conditions. This phenomenon contributes to the suppression of leakage current and partial discharges on insulator surfaces. Silicone rubber has been used much for housing materials of polymer insulators. ATH is added to the silicone rubber for improvement of its resistance against surface discharge. In this paper, ATH with different particle size and content was added to the silicone rubber during compounding. Silicone rubber was deteriorated by a corona treatment. Hydrophobicity recovery rate after corona treatment and arc resistance of silicone rubber were investigated. Hydrophobicity recovery rate of silicone rubber was evaluated by the measurement of contact angle. Arc resistance was evaluated by measuring weight loss of silicone rubber after arc resistance test. It was observed that the hydrophobicity recovery rate and arc resistance of silicone rubber were different when different particle size and content of ATH were added.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.82-82
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• 2009

본 연구에서는 Glass ceramic $SiO_2-CaO-Al_2O_3$를 사용하여 적층형 칩 퓨즈를 제조하였다. 퓨즈의 용단 특성 및 IR특성을 개선하기 위하여 기공조제로써 Corn starch 파우더(x=5, 10, 20, 30, 40, 50wt%)를 혼합하여 기공을 형성하게 하였다. 미세구조 관찰 결과 Corn starch 파우더의 함량이 증가함에 따라 기공률이 증가하였다. 또한 전극의 선폭(x=50, 100, 150, $200{\mu}m$)을 변화 시킴으로써 전극의 폭이 커질수록 저항값이 줄어든다는 것을 알 수가 있었다. 기공층 도입을 통하여 적층형 칩 퓨즈의 용단 특성의 개선 및 ARC 억제가 가능하였다.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.604-605
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• 2010

산업이 고도화 됨에 따라 박막 코팅에 대한 수요가 점차 증가하고 있으며 이에 따라 플라즈마를 이용한 마그네트론 스퍼터 시스템에 대한 수요 역시 증가하고 있다. 코팅 공정에서 가장 문제가 되는 것은 고압의 플라즈마 발생장치를 사용함으로써 야기되는 아크현상이라 할 수 있다. 따라서, 플라즈마 전원 장치의 핵심 기능 중의 하나는 아크 차단 성능이라 할 수 있으며 가능한 한 최소의 아크 에너지를 유지할 필요가 있다. 아크를 억제하는 방법은 최단 기간 내에 아크를 검지하여 출력을 차단함으로써 아크 발생에 필요한 에너지의 유입을 감소시키는 방법이 사용되고 있다. 본 연구에서는 아크를 검지하는 기존의 방식을 살펴보고 최단기간에 아크를 검지할 수 있는 새로운 형태의 검지 방식을 제안한다.

• Journal of Surface Science and Engineering
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• v.37 no.3
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• pp.169-174
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• 2004

MgO thin films were reactively deposited using an internal inductively coupled plasma assisted sputtering method varying reactive gas ratio to get stoichiometric film composition, and bipolar dc substrate bias to suppress micro arcs. The minimum frequency required for arc suppression was about 10KHz depending on ICP power. Their crystallinity was analyzed using X-ray diffraction and surface morphology using AFM. The surface was very smooth with rms roughness less than 0.42nm. The preferred orientation of the films were changing from (200) to bulk-like characteristics as Ar: $O_2$ratio was controlled to 10 : 2. Optical emission spectroscopy revealed that there were two distinct discharge modes: a blue one and a green one, where enhanced emission from Ar and Mg were observed. This cannot simply be understood by metallic or oxide mode of reactive sputtering due to ICP coupled to magnetron discharge.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.232-237
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• 2000

Thermopiezoelastic snap-through phenomena of piezolaminated plates are numerically investigated by applying a cylindrical arc-length scheme to Newton-Raphson method. Based on the layerwise displacement theory and von-Karman strain-displacement relationships, nonlinear finite element formulations are derived for thermopiezoelastic composite plates. From the static and dynamic viewpoint, nonlinear thermopiezoelastic behavior and vibration characteristics are studied for symmetric and eccentric structural models with various piezoelectric actuation modes. Present results show the possibility to enhance the performance of thermal structures using piezoelectric actuators and report new phenomena, namely thermopiezoelastic snapping, induced by the excessive piezoelectric actuation in the active suppression of thermally buckled large deflection of piezolaminated plates.

• Clinical and Experimental Reproductive Medicine
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• v.40 no.4
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• pp.155-162
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• 2013

Objective: Stress is known to be an inhibitor of the reproductive hypothalamic-pituitary-gonadal (HPG) axis. However, the neural and molecular connections between stress and reproduction are not yet understood. It is well established that in both humans and rodents, kisspeptin (encoded by the kiss1 gene) is a strong stimulator of the HPG axis. In the present study we hypothesized that endocannabinoids, an important neuromodulatory system in the brain, can act on the HPG axis at the level of kiss1 expression to inhibit reproductive function under stress. Methods: Adult male Wistar rats were unilaterally implanted with an intracerebroventricular cannula. Afterwards, the animals were exposed to immobilization stress, with or without the presence of the cannabinoid CB1 receptor antagonist AM251 (1 ${\mu}g/rat$). Blood samples were collected through a retro-orbital plexus puncture before and after stress. Five hours after the stress, brain tissue was collected for reverse transcriptase-quantitative polymerase chain reaction measurements of kiss1 mRNA. Results: Immobilization stress (1 hour) resulted in a decrease in the serum luteinizing hormone concentration. Additionally, kiss1 gene expression was decreased in key hypothalamic nuclei that regulate gonadotrophin secretion, the medial preoptic area (mPOA), and to some extent the arcuate nucleus (ARC). A single central administration of AM251 was effective in blocking these inhibitory responses. Conclusion: These findings suggest that endocannabinoids mediate, at least in part, immobilization stress-induced inhibition of the reproductive system. Our data suggest that the connection between immobilization stress and the HPG axis is kiss1 expression in the mPOA rather than the ARC.