• 한국환경과학회지
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• 제10권5호
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• pp.351-358
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• 2001

The main purpose of this study was to investigate the characteristics of cylindrical electrostatic precipitator with centrifugal effect in viewpoints of pressure drip and collection efficiency, experimentally. The experiment was carried out for the analysis of current-voltage, pressure drop and collection efficiency with various experimental parameters such as the applied voltage, inlet velocity, inlet size and inlet type(upper and bottom), etc. In the results, the pressure drops were estimated as 27~54, $34~63mmH_2O$ for inlet size $15mm{\tiems}30mm$ and $30mm{\tiems}60mm$, respectively. The collection effeciencies were shown over 90% with the small inlet size($15mm{\tiems}30mm$) for the applied voltage 40kV, inlet velocity(15~21m/s), and 51~89% with the large inlet size ($30mm{\tiems}60mm$). Moreover, in the applied voltage 0kV and inlet size $15mm{\tiems}30mm$, the collection efficiency induced by centrifugal force was represented as about 35% with inlet velocity 15 - 21m/s.

• 한국위성정보통신학회논문지
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• 제8권4호
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• pp.124-129
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• 2013

PPS 구조가 삽입된 N형 실리콘 제어 정류기 소자를 마이크로 칩의 고전압 I/O 응용을 위해 연구하였다. 종래의 NSCR_PPS_Std 표준소자는 매우 낮은 스냅백 홀딩 전압을 갖는 전형적인 SCR 특성을 가지고 있어 정상적인 동작 동안 래치업 문제가 나타나는 것으로 보고되고 있다. 그러나 본 연구에서 제안하는 CPS 및 부분적으로 형성된 P-Well(PPW) 구조를 갖는 변형된 NSCR_PPS_CPS_PPW 소자는 높은 래치업 면역과 트리거링 전압의 조절이 용이한 안정한 ESD 보호 성능을 나타내어 고전압 동작용 마이크로 칩의 정전기보호 소자로 적용 가능함을 확인하였다.

• 조명전기설비학회논문지
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• 제25권7호
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• pp.83-91
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• 2011

Even if smoke, fumes, mist or dust particles are removed by electrostatic precipitators (ESPs), the occurrence of ozone, which is harmful to human body, has to be severely restricted in the indoor environments of hospitals, offices, and workshops. Therefore, the two-stage ESP generating positive corona at the ionizer is typically used because it creates less ozone than the two-stage ESP generating negative corona at the ionizer. In order to predict the collection performance and the optimal design of the two-stage ESP applied to positive high-voltage, particle concentration is experimentally investigated in this paper. In addition, particle motion within the collector section is also numerically analyzed. The positive corona discharge current of the ionizer is found to be affected by the applied voltage in the collector section but less so by the particle concentration. Particle concentration shows a minimum near the high voltage electrode of the collector section. The minimum value of the collection efficiency is almost proportional to gas velocity. When the collector length decreases, the minimum value of the collection efficiency increases. Charged particles entering the collector region are linearly deflected towards the grounded plate by an electric field. From the above experimental and numerical results, two empirical equations on the concentration ratio and the collection efficiency are derived, and are in good agreement with the experimental data.

• 한국생산제조학회지
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• 제24권3호
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• pp.270-277
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• 2015

In this paper, we describe the production of a specific electrostatic-type scanning electron microscope based on miniaturization for application in other types of vacuum equipment. The initial configuration of the SEM starts with a minimal configuration that allows people to view sample images. After improving the stability of the SEM operation and resolution, we conducted experiments on identifying the characteristics and development of an einzel-type condenser lens with reference to the demagnification lens system of an SEM. The experiments were conducted at an acceleration voltage of 5 kV and we found the shape of the lens to be more reliable than a conventional lens. The lens was then added to improve the resolution in the nanometer region. The current measured on the sample was approximately 40 pA and its magnification was 4,000 times.

• 환경위생공학
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• 제10권2호
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• pp.79-88
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• 1995

The electrostatic precipitation of Auto- Bias has the advantages of a little of power consumption by the voltage to apply only at ionizer and the prevention of fire danger by current flow over. As this ionizer wire was used WXN- Pt material of diameter 90$\mu $m, that improved ion efficiency and safety, simplified a existing source of electric power by induced Auto- Bias voltage. Also, the new type collector used electric conductivity- film wag superior a electric safety and dust collection efficiency and was possible to wash it by water. As a experiment result of this Auto- Bias electrostatic collector, the induced Auto- Bias voltage by appling D.C 4.0∼6.0kV at ionizer was 1.3∼2.3kV and then the power consumption by applied voltage was 8- l8W. The pressure loss of collector by the amount of flowing was 6.1 OmmH$_{2}$O in 300m$^{3}$/hr and showed a safe state of the dust collection. The collection efficiency by particle size was 65.1-95.8% in 0.5∼5.0$\mu $m. After corona discharge of ionizer, the remains ozone concentration was found much lower than that of ACGIH or air pollution criteria in Korea.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.432-432
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• 2010

Organic light emitting diodes (OLED) thin films were fabricated by Electrostatic spray deposition (ESD). In this study, we reported the thickness, morphology, current efficiency, luminescence of OLED fabricated by ESD. These results were compared with the spin coating method, and showed that also ESD is a good fabrication method for OLED because of its characteristics similar with the results using spin coating. The active layer consists of organic blends with Poly(N-vinylcarbazole) (PVK), 2-(4-Biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N'-Bis(3-methylphenyl) -N,N'-bis(phenyl)-benzidine (TPD), Tris(2-phenylpyridine)iridium(III) (Ir(ppy)3), and the structure of OLED consists of aluminum (Al), lithium fluoride (LiF), organic blends, PEDOT:PSS and Indium-tin-oxide (ITO), which was used as the top cathode, cathode interfacial layer, emitting layer and bottom anode, respectively. The results suggest that Electrostatic spray deposition is a promising method for the next generation of OLED fabrication since it has a probability fabricating large-area thin films.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1175-1181
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• 2013

The aim of this paper is to design and evaluate a high concentration, high penetration unipolar corona ionizer. The electrostatic characteristics in terms of voltage-current relationships of the present ionizer in the discharge zones for positive and negative coronas were discussed. Using ion current measurement, the concentration and penetration of ions were evaluated at corona voltages across the needle electrodes between 1 and 4 kV, flow rates between 1 and 5 L/min, and an operating pressure of 1 atm. In the discharge zone of the ionizer, the highest ion concentrations were found to be about $1.71{\times}10^{14}$ and $5.09{\times}10^{14}\;ions/m^3$ for positive and negative coronas, respectively. At the outlet of the ionizer, it was found that the highest ion concentration was about $1.95{\times}10^{13}$ and $1.91{\times}10^{13}\;ions/m^3$ for positive and negative coronas, respectively. The highest ion penetration for positive and negative coronas through the ionizer was found to be about 98 % and 33 %, respectively. The $N_it$ product for positive and negative coronas was also found to $1.28{\times}10^{13}$ and $7.43{\times}10^{13}\;ions/m^3s$, respectively. From the findings, this ionizer proved to be particularly useful as an aerosol charger for positive and negative charge before the detector in an electrical aerosol detector.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권4호
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• pp.495-502
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• 2014

Fast recovery diodes (FRDs) were developed using the $p^{{+}{+}}/n^-/n^{{+}{+}}$ epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, < $10^{-9}$ A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to ${\pm}5.5$ kV of HBM and ${\pm}3.5$ kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, $I_{pp,max}$, up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권3호
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• pp.109-113
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• 2005

It has been reported that the failure phenomenon and variation of electrical characteristic due to the effect of electrostatic discharge(ESD) in silicon devices. But we had fess reports about the phenomenon due to the ESD in the compound semiconductors. So there are a lot of difficulty to the phenomenon analysis and to select the protection method of main circuits or the devices. It has not been reported that the relation between the ESD stress and GaN devices, which is remarkable to apply the operation in high temperature and high voltage due to the superior material characteristic. We studied that the characteristic variation of the AlGaN/GaN HEMT current, the leakage current, the transconductance(gm) and the failure phenomenon of device due to the ESD stress. We have applied the ESD stress by transmission line pulse(TLP) method, which is widely used in ESD stress experiments, and observed the variation of the electrical characteristic before and after applying the ESD stress. The on-current trended to increase after applying the ESD stress. The leakage current and transconductance were changed slightly. The failure point of device was mainly located in middle and edge sides of the gate, was considered the increase of temperature due to a leakage current. The GaN devices have poor thermal characteristic due to usage of the sapphire substrate, so it have been shown to easily fail at low voltage compared to the conventional GaAs devices.

• 한국화재소방학회논문지
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• 제23권3호
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• pp.11-16
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• 2009

본 논문은 전기설비에서 사고 발생 징후를 검출하기 위한 방법을 기술하고 있다. 실험을 위해 전기설비의 부하는 백열전구로 구성하였고, 사고는 전기설비의 일부에 KS C IEC(Korea Standard C International Electrostatic Commission) 60112에 따른 내트래킹 시험장치를 연결하여 모의되었다. 모의사고는 정상상태에서 방전진전과 탄화형성 과정을 거쳐 트래킹파괴에 이르게 된다. 전기설비로부터 사고 징후 검출을 위해 전류 모니터를 이용하여 전기설비 전체의 전류를 측정하고 이를 분석하였다. 그 결과, 전류 파형의 특정 영역에서 사고의 진행 정도가 클수록 전류 펄스의 크기가 커지고, 발생 빈도도 증가하였다. 특히 전류파형에 대한 표준편차와 확률분포는 부하의 수와 무관하게 사고단계별로 뚜렷한 차이를 보였다.