• 한국안전학회지
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• 제22권1호
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• pp.36-39
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• 2007

It is important to know Minimum Ignition Energy(MIE) of flammable materials for ignition hazard of chemical processes etc.. Currently a capacitor discharge is used mainly to measure the MIE. Then, it is impossible to control actively discharge energies and discharge time because the MIE measurement uses a high voltage capacitor and fixed capacitor. However, the control of discharge energy and discharge time will be convenient if self-sustain discharge is used. In this paper, we measured the MIE by self-sustain discharge of a pulse shape to propose the new measuring method of the MIE. AS a result, ignition energies are increased gradually as discharge duration time gets longer, and discharge current grows larger. Also, an arc discharge and a glow discharge occurred during the experimental period, and the ignition by glow discharges happened when discharge duration time was $90{\mu}s$, discharge current was 8A and 1A Especially, the MIE occurred the 0.05mm and 0.08mm of the gap distance between discharge electrode in the same discharge duration time.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2256-2261
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• 2017

Carbon nanotube (CNT) and alumina ($Al_2O_3$) are synthesized into hybrid composites, and an advanced electrical discharge machining (EDM) system is developed for the machining of hard and conductive materials. CNT nanoparticles are mixed with $Al_2O_3$ powder and the $Al_2O_3$/CNT slurry is sintered by spark plasma. The hardness and the electrical conductivity of the $Al_2O_3$/CNT hybrid composite were investigated. The electrical discharge is controlled by a capacitive ballast circuit. The capacitive ballast circuit is applied to the tungsten carbide and the $Al_2O_3$/CNT hybrid composite. The voltage-current waveforms and scanning electron microscope (SEM) images were measured to analyze the characteristics of the boring process. The developed EDM process can manufacture the ceramic based hybrid composites, thereby expecting the variety of applications.

• 한국수소및신에너지학회논문집
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• 제8권1호
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• pp.31-41
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• 1997

In order to investigate the mechanism of electrochemical hydrogenation reaction on Zr-based Laves phase hydrogen storage alloy electrodes, electrochemical charge/discharge characteristics, potentiostatic/dynamic polarizations and electrocehmical impedance spectroscopy(EIS) of Zr-Ti-Mn-Ni and Zr-Ti-Mn-Ni-M(M=Fe, Co, Al) alloys were examined. Electrochemical discharge capacities of the alloys were quite different with gas charge capacities. Therefore, it was considered that discharge capacities of the alloys depend on electrochemical kinetic factors rather then thermodynamic ones. Discharge efficiencies were increased linearly with exchange current densities. The results of potentiostatic/dynamic polarization measurements showed that electrochemical charge and discharge reaction of Zr-based Laves phase hydrogen storage alloys is controlled by charge transfer process at the electrode surface. The EIS measurements also confirmed this result.

• Nuclear Engineering and Technology
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• 제35권3호
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• pp.226-233
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• 2003

The discharge characteristics of a prototype ion source was investigated, which was developed and upgraded for the NBI (Neutral Beam Injection) heating system of KSTAR (Korea Superconducting Tokamak Advanced Research). The ion source was designed for the arc discharge of magnetic bucket chamber with multi-pole cusp fields. The ion source was discharged by the emission-limited mode with the control of filament heating voltage. The maximum ion density was 4 times larger than the previous discharge controlled by a space-charge-limited mode with fully heated filament. The plasma (ion) density and arc current were proportional to the filament voltage, but the discharge efficiency was inversely proportional to the operating pressure of hydrogen gas. The maximum ion density and arc current were obtained with constant arc voltage ($80{\sim}100V$), as $8{\times}10^{11}cm^{-3}$ and 1200 A, respectively. The estimated maximum beam current was about 35 A, extracted by the accelerating voltage of 80kV.

• KIEE International Transactions on Electrophysics and Applications
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• 제2C권5호
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• pp.253-257
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• 2002

A new Current-Controlled Driving Method that can drive AC PDPs with low voltage and high luminous efficiency for the sustaining period is presented. In this driving method, the voltage source is connected to a storage capacitor and the stored voltage is delivered to the panel through LC resonance. Thus, this driving method can drive the panel with a voltage source as low as about half of the voltage necessary in the conventional driving methods. The discharge current flowing into the AC PDP is limited in this method. Thus, the power consumption for the discharge is reduced and the discharge input power to output luminance efficiency is improved. Experimental results using this driving method showed that we could drive an AC PDP with a voltage source as low as 146V and that high luminous efficiency of 1.33 1m／W can be achieved.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2003년도 춘계 학술논문발표회 논문집
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• pp.303-308
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• 2003

가연성 물질의 최소점화에너지(Minimum Ignition Energy; MIE)를 아는 것은 화학공정 등의 안전성 평가에 중요한 것이다. 현재 MIE의 측정에는 주로 용량성 불꽃방전이 이용되고 있다. 용량이 큰 커패시터를 이용한 방전에서는 MIE가 크게 되는 경향이 있고, MIE가 회로정수에 의존한다는 것이 실험적으로 알려져 있다. 이 현상은 방전회로의 시정수와 점화를 위한 에너지의 수송시간과의 관계에 의해 이론적으로 설명하는 것이 가능하게 되었다.(중략)

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1412-1413
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• 1996

Li ion battery have many advantages such as high energy density, high voltage and low self discharge, so it will replace conventional Ni/Cd battery. But, charge-discharge characterization of Li battery is controlled by weight ratio of electrodes (Cathode/Anode). So, we performed a study on relation between charge/discharge characterization and weight ratio (cathode/anode).

• 태양에너지
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• 제9권1호
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• pp.70-77
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• 1989

Sodium pyrophosphate that melting point is $79-80^{\circ}C$ have been Studied on heat storage and heat discharge. In heat storage process, sodium pyrophosphate was kept up initial temperature $50^{\circ}C,\;60^{\circ}C,\;70^{\circ}C$ which melt by heated water at temperature $85^{\circ}C,\;90^{\circ}C,\;95^{\circ}C$. In heat discharge process, initial temperature of sodium pyrophosphate was maintained at temperature $85^{\circ}C,\;90^{\circ}C,\;95^{\circ}C$ which varied cooling temperature $50^{\circ}C,\;60^{\circ}C,\;70^{\circ}C$. The experiment has been reached conclusions as follows. 1) Heat transfer properties of phase change material is controlled by conduction during heating and cooling process. 2) The temperature increased rapidly at initial stage and transient region increase slowly because of characteristic of latent heat. 3) The lower cooling water temperature is the less the time that get to thermal equivalent state take during discharge process. 4) The higher cooling water temperature is the less temperature difference between top and bottom in P.C.M during discharge process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.285-288
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• 1996

The electronic operation of the gas discharge tube is controlled by the electrical energy as sinusoidal waveform in arbitrary frequency range, or as a sequence of pulses at a wide range of duty cycle, the gas composition, the kind of electrode and the vessel geometry. In this paper, the pulsed mode operated gas discharge tube is composed with mixed gas of IIg-Ne ( 10 Torr ), in the tube of 15.0 mm outer diameter and has variable color from red to blue with changing frequency and pulse width in high voltage. As increasing pulse width and frequency in the gas discharge tube, the phenomenons that the electron temperature in the positive column increases and the radiation from atoms of higher upper state energy levels increases, exist. The color have the locus from red (0.4972, 0.3128) to blue (0.2736, 0.2619) in CIE chromacity diagram with increasing pulse width and frequency. The changing method of pulse width and frequency has been shown to be suitable for the luminous color control.

• 에너지공학
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• 제15권3호
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• pp.154-159
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• 2006

본 연구는 PWM 방식의 스크롤 압축기를 적용한 에어컨 시스템의 압축기 운전주기, 실내 온도, 그리고 실외온도를 변화시키면서 시스템 에어컨의 최적효율을 나타내는 압축기 토출온도 상관식을 도출하고자 실험연구를 수행하였다. 실험은 실내 및 실외 온도변화에 따른 시스템의 성능 및 압축기 토출온도를 측정 하고자 다양한 온도를 설정하였다. 압축기 토출온도는 로딩듀티와 실외온도가 증가함에 따라 선형적으로 증가하였다. 로딩듀티(loading duty)와 실외온도 변화에 따른 압축기 토출온도는 실내온도 변화보다 실외온도의 변화에 더 크게 변화하였다. 압축기 토출온도 상관식은 실외온도, 실내온도, 그리고 로딩듀티의 함수로 표현되었으며, 실험으로부터 획득된 압축기 토출온도와 최대 $3^{\circ}C$ 이내에서 만족함을 확인하였다.