• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.333-333
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• 2011

We have investigated the breakdown properties in liquids by high voltage pulse system. High voltage pulse power system is consisted of the Marx-generator with two capacitors (0.5 ${\mu}F$, withstanding voltage is 40 kV), to which the charging voltage can be applied to maximum 30 kV DC, spark gap switch and charging resistor of 20 $M{\Omega}$. We have made use of tungsten pin electrodes of anode-cathode (A-K), which are immersed into the liquids. The breakdown voltage and current signals are measured by high voltage probe (Tektronix P6015A) and current monitor (IPC CM-1.S). Especially the high speed breakdown or plasma propagation characteristics in the pulsed A-K gap have been investigated by using the high speed ICCD camera. We have measured the electron temperature through the Boltzmann plot method from the breakdown spectrums. Here the A-K gap has been changed by 1 mm, 2 mm, and 3 mm. The used liquids are distilled water and solution of salt (0.9 %). The output voltage and current signals at breakdown in distilled water are shown to be bigger than those in saline solution. The breakdown voltage and current characteristics in liquids will be discussed in accordance with A-K gap distances. It is also found that the electron temperatures and plasma densities in liquids are decreased in conformity with A-K gap.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.301-304
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• 2008

This paper presents the experimental results on breakdown characteristics in $N_2$ gas under non-uniform electric fields caused by both the positive and negative lightning impulse voltages. $N_2$ gas have an advantage of eco-friendly and cost reduction, and safety aspects. In order to analyze the impulse pre-breakdown processes in $N_2$ gas, we carried out measurements and observations of the impulse breakdown voltages, pre-breakdown current and luminous signals. They were measured by a voltage divider, a shunt and a photo-multiplier tube, respectively. Additionally, the characteristics of discharge channels were observed by high speed cameras. The breakdown voltages in the positive polarity was lower than those in the negative polarity.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.42-48
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• 1999

Engine misfire causes of the negative effect on exhaust emission such as HC, CO, and NOX . Moreover, it causes damage to the three-way-catalyst(TWC) system permanently. The crankshaft velocity fluctuation(CVF) method has been applied for the real cars as misfire detection system usually, which utilizes the crank angle sensor input to calculate the variation of the crankshaft rotational speed. But this approach has the limit due to the fact that three could be problem under certain engine condition like as deceleration or high speed condition . Therefore the development of new methods are requested today. This study introduced the new method of misfire detection using breakdown voltage(BDV) characteristics between spark plug electrouds.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.164-168
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• 1996

The relation between crystallinity and thermal history in low density polyethylene thin films and their effect on electric conduction phenomena and dielectric breakdown was studied. The low density polythylene thin films obtained by the solution growth method heat-treated at 140[$^{\circ}C$] for 2 h and subsequently cooling to various ways. The degree of crystallinity was estimated by the X-ray diffraction measurement for the specimen of slowly cooling, ICE quenching and liquid nitrogen quenching. The result shows that the crystallinity decreases become faster as the cooling speed increased, and that conduction phenomenon is governed by the space charge limited current in high field. It was found that the dielectric breakdown field increases with an increase in cooling speed and test number in self-healing breakdown method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.239-242
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• 1999

In this paper, we report the process/device design of high-speed, high-voltage SOI smart power IC for mobile communication system, high-speed HDD system and the electronic control system of automobiles. The high voltage LDMOS with 70V breakdown voltage under 0.8${\mu}{\textrm}{m}$ design rule, the high voltage bipolar with 40V breakdown voltage for analog signal processing, the high speed bipolar with cut-off frequency over 20㎓ and LDD NMOS for high density were proposed and simulated on a single chip by the simulator DIOS and DESSIS. And we extracted the process/device parameters of the simulated devices.

• 대한물리치료과학회지
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• 제22권2호
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• pp.43-47
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• 2015

Background : Many factors affect foot and ankle biomechanics during walking, including gait speed and anthropometric characteristics. This study examined the effect of walking speed on peak plantar pressure during the walking. Method : Thirty two normal healthy subjects (16 men, 16 women) were recruited. Peak plantar pressure was investigated using pressure distribution platforms (Pedoscan system) under the hallux heads of the first, second, and third metatarsal bones, and heel. Result : The results also suggest that slow walking speeds may decrease forefoot peak plantar pressure in patients with peripheral neuropathy who have a high risk of skin breakdown under the forefoot(p<0.05). Conclusion : The results also suggest that slow walking speeds may decrease forefoot peak plantar pressure in patients with restricted low extremity range of motion who have a high risk of skin breakdown under the forefoot.

• 디지털콘텐츠학회 논문지
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• 제18권6호
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• pp.1193-1198
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• 2017

본 논문에서 개발된 IGBT 구조는 DC 송배전을 위한 고전력 스위치 반도체로서 사용되며, 빠른 스위칭 속도 및 개선된 항복전압 특성을 확보하여, 향후 신재생 장거리 DC 송전을 위한 중요한 전자 소자로서 이용될 것이 기대되고 있다. 새로운 타입의 차세대 전력 반도체로서, 스위칭 속도를 향상시키면서 동시에 항복 전압의 특성을 개선시켜, 전력 손실 특성을 줄이도록 설계되었고, 높은 전류 밀도의 장점을 동시에 획득 가능하다. 이러한 개선된 특성은 Planar IGBT의 N-drift 영역에 $SiO_2$를 추가로 도입함으로서 얻어지며, Sentaurus TCAD 시뮬레이션 툴을 사용하여, 비교 분석하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.65-68
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• 2000

Polyethylene, has long history and is widely used, was researched due to good electrical properties by many authors. But PE under stress has the critical defects of space charge accumulation and tree growth, so various methods such as catalyst, additives and blend to improve these problems have been execute, of which we selected blending method. As in our previous papers we investigated electrical conduction, dielectric and AC dielectric breakdown characteristics, we did DC dielectric breakdown characteristics in this paper. We selected pure LLDPE, pure EVA and LLDPE films mixed with EVA as specimens, which were mixed with the weight percentages of 50, 60, 70 and 80[wt%] to be thin film. DC applying voltage speed was 500[V/sec]. The relation between dielectric breakdown characteristics and the variations of super structure due to mixing was investigated, and especially trap level at amorphous region, threshold energy increment of conductive electron at free volume were considered.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.105-109
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• 2002

The short-term AC breakdown strength of laminated polypropylene insulating Paper (PPLP) has been studied for cold dielectric of high temperature superconductivity power cables. The design and operating conditions of the electrode system for studying of short-term breakdown strength of one-layer and multi-layer PPLP samples are discussed in liquid nitrogen(LN2) state. The influence of various operating factors (geometry and dimension of electrodes, speed of tested voltage, thickness of test sample) on the value of short-term AC breakdown strength at cryogenic temperature has been established.

• 한국레이저가공학회지
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• 제12권4호
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• pp.17-25
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• 2009

The surface cleaning method based on the laser-induced breakdown (LIB) of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. In the laser shock cleaning (LSC) process, a high-power laser pulse induces optical breakdown of the ambient gas above the solid surface covered with contaminant particles. The subsequently created shock wave followed by a high-speed flow stream detaches the particles. In this work, a novel surface cleaning process using laser-induced breakdown of liquid is introduced and demonstrated. LIB of a micro liquid jet increases the shock wave intensity and thus removes smaller particle than the conventional LSC method. Experiments demonstrate that the cleaning force and cleaning efficiency are also increased significantly by this method.