• Current Industrial and Technological Trends in Aerospace
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• v.7 no.1
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• pp.68-78
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• 2009

In this paper, the electrostatic charging and discharging mechanism, and its effects in space plasma environment are reviewed and the system design control documents, ESD analysis tools and modelling techniques, and the SPIS program in Europe are introduced. A design of the satellite system against the electrostatic discharge (ESD) effects in space plasma environments is carefully taken into account at the early stage of development. In a view of the space system design, it really depended on the mission of system, electrical and mechanical configuration, system operation, and orbit condition. Behavior of the electrons and the ions in those environments may be occurred the sever problem to the satellite operation. So it is carefully understood for implementation of the satellite system. By this reason, the space environments and its effects have been comprehensively studied in U.S.A and Europe.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.309-315
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• 2018

In this paper, propose an efficient arc detection and control method to achieve fast machining speed, improved precision and surface roughness in discharge machining, especially for carbide and hard material processing and metal processing using discharge phenomenon as energy. A single discharge waveform is divided into three sections of Td (Time-Delay), Ton (Time-on) and Toff (Time-off) and the gate control timing is simulated using the HDL language. In this paper, we analyze the effect of the gap between the electrode and the workpiece on the machining results by determining the operation of the servo mechanism by sampling the Td section through the comparator circuit. As a result of the analysis, the Td section of the formed waveform was more precisely sampled at a high speed and the results were improved when applied to the gap control between the electrode and the workpiece.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.142-143
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• 2000

레이저는 입력을 증가시킴에 따라 레이저의 꺼짐 상태에서 레이저의 켜짐 상태로 전이한다. 그러나 그 전이 현상에 대해서는 아직 밝혀진 바가 없다. 이때까지 이 현상은 처음 자발전이의 빛이 점점 유도전이로 바뀌며 그 빛이 점점 세어져 레이저의 출력이 생기기 시작하고 이것이 레이저 입력의 증가에 따라 연속적으로 발전하는 것으로 알려져 왔다. 그러나 이러한 결과에 반대되는 결과들이 최근 밝혀지고 있다[1-2]. 그것은 이산화탄소 레이저에서 이득을 변조시키면 방전이 불안정해지고 그 결과 레이저의 출력도 불안정해 지는데 특히 발진 문턱 근처에서 레이저의 출력은 불규칙 적으로 레이저의 출력이 사라지는 현상이 생긴다는 것이다[1]. 또 다른 하나는 cw Nd:YAG 레이저를 아크 램프로 여기시켜 발진시키면 발진 문턱 근처에서 이 레이저의 출력도 불규칙적으로 레이저의 출력이 사라지는 것으로 나타난다[2]. 이 현상은 레이저의 입력을 증가시킴에 따라 레이저의 꺼짐 상태에서 발진 상태로 전이할 때 그 중간에 불규칙적인 레이저의 꺼짐 상태가 존재한다는 것이 된다. 이 현상이 비선형 동력학의 특이한 현상 중의 하나인 on-off 간헐성임[3]이 밝혀졌다. (중략)

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.32-37
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• 2004

The charge/discharge capacity of natural graphite anode in lithium secondary batteries was examined as a function of charge/discharge rate. When the natural graphite anode was galvanostatically cycled in the range of 0.0-2.0V $(vs.\;Li/Li^+)$, the charging capacity decreased with an increase in the charging rate, which is caused by an earlier approach to the charging cut-off (0.0 V) before the complete charging that is in turn caused by an ever-increasing overpotential at higher rates. Even if the overpotential of discharging reaction also increased at higher discharge rates, the discharging reaction took place in the range of 0.0-0.3 V that is far below the discharge cut-off (2.0 V). As a result, the discharge capacity was not affected by the discharge rate because all the lithium ions once intercalated are fully discharged even at high current condition. As the overpotential of lithium deposition reaction also increased at high current condition, the charge capacity of natural graphite could be enlarged by lowering the charging cut-off voltage below 0.0 V, There is, however, a limitation for the lowering of cut-off voltage because the resistance for lithium deposition is smaller than that of lithium intercalation into graphite. When the charge cut-off voltage was lowered down to -0.04 V under IC condition, lithium ions were inserted into graphite without lithium deposition such that the discharge capacity could be raised up to $11\%$.

• Analytical Science and Technology
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• v.6 no.4
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• pp.369-374
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• 1993

Plasma oscillation has been observed during the development of the glow discharge as detector for gas chromatography. The variation of oscillation frequency shows the better stability and detection limits than the changes in the dischange curent. To investigate the range of useful operating conditions and to gain insight into the mechanism, the effect of experimental parameters on plasma oscillation have been studied. This study includes the variation of discharge current, pressure and discharge gap. Frequency ranges of 10KHz to 10MHz have been observed with the various shapes of oscillation. Two kinds of mode for oscillation are observed with the variation of electrode gap at low pressure and low voltage.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.27-31
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• 1998

We investigated visible light radiated from Plasma focus device by time-resolved analyzed method and time-integrated analyzed method. Plasma focus consisted of two coaxial electrodes is a device that translated from electric energy of maximum 40 kV/20 kJ in capacitor banks into visible light by electric discharge. Spectral analysis is using Monochromator(f =0.5m). Time-resolved spectrum is analyzed with a oscilloscope the light pulse of constant wavelength and time-integrated spectrum does with densitometer the film which developed a constant range of wavelength. The optimum condition of visible emission was that the discharging voltage was 17kV and the gas pressure 0.5 torr Ar.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.128-133
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• 2008

This paper describes underwater discharge phenomena and breakdown characteristics in case that the standard lightning impulse voltage is injected to the needle and spherical electrodes installed in the hemisphere water tank. The objective of this work is to understand the basic features related to transient ground impedance against lightning surges. The discharge luminous images were observed and the dependence of breakdown voltage on the polarity of applied voltage and water resistivity were investigated. As a consequence, streamer corona is initiated at the tip of needle and spherical electrodes and is propagated toward grounded tank with stepwise extension. The breakdown voltage characteristics measured as a function of water resistivity showed V-shaped curves. Breakdown voltage and time curve of needle electrode is higher than that of spherical electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.640-643
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• 2004

유도결합형 플라즈마는 낮은 가스 압력에서도 고밀도의 플라즈마를 발생시키기 때문에 무전극 램프에 많이 적용되고 있다. 그리고 무전극 램프는 장 수명을 실현하고 고품질의 빛을 발생하기 때문에 앞으로 광범위하고 다양한 장소에 사용이 예상된다. 본 논문에서는 유도결합형 플라즈마를 이용한 아르곤 가스의 방전 특성 중에서 색 좌표 특성을 살펴보았다. 즉, 외부 안테나에 의해 발생된 13.56[MHz]의 RF Power를 방전관 내부로 전달하고, 아르곤 가스 압력과 RF Power 변화에 따른 아르곤 가스의 방전 특성을 측정하였다. 또한, 유도결합형 플라즈마를 방전시키기 위한 아르곤 가스의 압력은 1[mTorr]에서 100[mTorr], RF 전력은 10[W]에서 120[W]이며 이의 색 좌표 특성과 스펙트럼을 살펴보았다. 측정 결과 RF 출력이 증가하면 색 좌표의 x, y 값이 동시에 감소하였다. 아르곤 가스 압력이 증가하면 농도의 증가로 인해 발광이 어려웠으며, 색 좌표 특성은 압력이 증가하면서 y 값은 변화가 적었으나 x 값이 100[mTorr]일 크게 증가하는 현상이 나타났다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.7-11
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• 2008

The fluorescent lamp is one of a discharge lane that is used by electric discharge to transfer from electrical energy to light The fluorescent lamp needs a ballast stabilizer when turn it on because it has negative resistance. Characters of electric discharge and transformed characters of ballast stabilizer are connected closely. Therefore, bring out best design directive that consider economical efficiency and term of a application is very important for both characters matching. In this case, we will team to develop tester and functions for expression for recognizing the end of fluorescent lamp life to solve fire problem and losing efficiency of light when a fluorescent lamp goes the end of the expected its life span.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.1
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• pp.78-82
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• 2019

This paper addressed the spectrum of ultrasonic waves produced by arc and/or coronal discharge inside the switchboard. Portable ultrasound sensors are useful for detecting discharge phenomena, such as coronal means in electrical systems. However, a typical handheld ultrasound detector has a disadvantage of determining the type of problem by listening to the sound characteristics and predicting the results, as a result of the determination of whether a discharge is present. Therefore, a new method of analysis is required to distinguish ultrasonic characteristics. In this paper, we published an ultrasound analysis case study to visualize the sound of ultrasonic waves measured with ultrasonic sensors. From the results of the experiment, it was possible to detect coronal discharge and serial arc discharge without interference by the ultrasonic detection system.