• 한국자동차공학회논문집
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• 제8권1호
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• pp.23-31
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• 2000

Knock and misfire, kinds of abnormal combustion, are highly undesirable effect on the internal combustion engine. So, it is important to detect these avnormal combuition and control the ignition timing etc. to avoid these mal-effect factors in real engine system. In this study, the system which detects the knock and the misfire using by spark plug is presented. This system is based on the effect of modulation breakdown voltage(BDV) between the spark gaps. The voltage drop between spark plug electrodes, when an electrical breakdown is initiated, depends on the temperature and pressure in combustion chamber. So, we can detect knock and misfire that produce changes in gas temperature and pressure (consequently, its density) using by BDV signal change which carries information about the character of combustion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.297-300
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• 2004

In this paper, we investigated insulation property of epoxy resin which includes elastomers to improve mechanical property, as varied to additive elastomer contents and to moisture absorption. There are four samples with 5[phr], 10[phr], 15[phr] and 20[phr]. we experimented to acquire insulation property(absorption rate, dissolution rate, apparent rate) and electrical property(perittivity, $tan\delta$, BDV) during respectively the time such as 6[h], 12[h], 18[h], 24[h] for moisture absorption. According to the experimental results, it is appeared that when the additive elastomer contents are increasing or when specimens remain more moisture, absorption rate, dissolution rate, permittivity and $tan\delta$ are slightly increasing but apparent rate and BDV(break-Down Voltage) strength are decreasing in particular, elastomer content [20]phr appeared remarkedly the more increase or decrease than others.

• 한국결정성장학회지
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• 제19권2호
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• pp.102-105
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• 2009

$BaTiO_3$ 입자 크기가 MLCCs의 절연 특성 및 MLCCs 특성 열화에 미치는 영향을 알아보기 위해 서로 다른 입자를 사용하여 제작한 MLCCs의 가속열화시험을 $150^{\circ}C$, 75 V조건에서 실시하였다. 실험에 사용된 MLCCs는 각각 $0.525{\mu}m$, $0.555{\mu}m$, $0.580{\mu}m$의 입자 크기를 가지는 $BaTiO_3$와 Ni계 전극을 사용하여 상용화된 공정을 통해 제조되었다. 제조된 MLCCs에 대해 정상 유무 확인을 위해 X5R조건 하에서 TCC(Temperature Coefficient of Capacitance) 측정을 통해 유전 변화율에 대해 알아보았다. 세 가지 입자 크기에 따른 절연저항의 거동을 알아보기 위해 BDV(Breakdown Voltage)를 실시하였고, 가속열화시험 후 입자의 크기에 따른 MLCCs 열화의 정도와 원인을 알아보기 위해 XPS(If-ray photoelectron spectroscopy)를 통해 고장분석을 하였다. $BaTiO_3$의 입자 크기가 작을수록 절연파괴저항 및 절연저항 열화에 우수한 특성을 나타내었고, XPS 분석 결과 확인된 NiO peak과 $BaTiO_3$ peak 감소를 통해 MLCCs 열화원인이 유전체의 산소 환원과 환원된 산소와 전극간 반응임을 알 수 있었다.

• International Journal of Safety
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• 제1권1호
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• pp.36-42
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• 2002

This paper is aimed at predicting the life of rubber insulating gloves under normal operating stresses from relatively rapid test performed at higher stresses. Specimens of rubber insulating gloves are subject to multiple stress conditions, i.e. combined electrical and thermal stresses. Two modes of electrical stress, step voltage stress and constant voltage stress are used in specimen aging. There are two types of test for electrical stress in this experiment: the one is Breakdown Voltage (BDV) test under step voltage stress and thermal stress and the other is lifetime test under constant voltage stress and temperature stress. The ac breakdown voltage defined as the break-down point of insulation that leakage current excesses a limit value, l0mA in this experiment, is determined. Because the very high variability of aging data requires the application of statistical model, Weibull distribution is used to represent the failure times as the straight line on Weibull probability paper. Weibull parameters are deter-mined by three statistical methods i.e. maximum likelihood method, graphical method and least squares method, which employ SAS package, Weibull probability paper and FORTRAN, respectively. Two chosen models for predicting the life under simultaneous electrical and thermal stresses are inverse power model and exponential model. And the constants of life equation for multistress aging are calculated using numerical method, such as Gauss Jordan method etc.. The completion of life equation enables to estimate the life at normal stress based on the data collected from accelerated aging test. Also the comparison of the calculated lifetimes between the inverse power model and the exponential model is carried out. And the lifetimes calculated by three statistical methods with lower voltage than test voltage are compared. The results obtained from the suggested experimental method are presented and discussed.

• 한국전기전자재료학회논문지
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• 제37권3호
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• pp.286-291
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• 2024

Research on aged insulation of cables by stress is constantly being considered for reliable and stable power transmission of offshore wind farms. This study aimed to evaluate the insulation characteristic of aged XLPE (cross-linked polyethylene) insulation for application of offshore wind farms. In this study, The XLPE insulation of cable was set as various mechanical strains. The XLPE insulation is exposed to the mechanical stress below yield strain of 5%, 10%, and 20%. Aged samples were tested by using the method of AC BDV (alternative current breakdown voltage), tensile strength, elongation, and SEM (scanning electron microscope) to obtain insulation characteristics. The experimental results show that the dielectric breakdown of the sample with a strain 20% was 50% lower than the unaged sample; thereby, demonstrating that the mechanical strain that occurred in the submarine cables can weaken the insulation characteristics. Therefore, mechanical strain should be monitored when laying and operating submarine cables for offshore wind farms.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.14-17
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• 2006

This paper describes a novel processing technique for fabrication of polymer-derived SiCN (silicone carbonitride) microstructures for super-temperature MEMS applications. PDMS (polydimethylsiloxane) mold is fabricated on SU-8 photoresist using standard UV photolithographic process. Liquid precursor is injected into the PDMS mold. Finally, solid polymer structure is cross-linked using HIP (hot isostatic pressure) at $400^{\circ}C$, 205 bar Optimum pyrolysis and anneal ins conditions are determined to form a ceramic microstructure capable of withstanding over $1400^{\circ}C$. The fabricated SiCN ceramic microstructure has excel lent characteristics, such as shear strength (15.2 N), insulation resistance ($2.163{\times}10^{14}\;{\Omega}$) and BDV (min. 1.2 kV) under optimum process condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1155-1158
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• 2003

In this paper, we studied on the electrical characteristics of insulation material of elastomer epoxy. As the results of test, properties of epoxy represent differently according to elastomer contents. Also, its permittivity, tan ${\delta}$ and BDV(Break-Down Voltage) strength show big difference when those compare before moisture absorption test and after moisture absorption test. From this test we find results that mush elastomer contents can cause insulation properties to degrade.

• 한국수의병리학회:학술대회논문집
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• 한국수의병리학회 2003년도 추계학술대회초록집
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• pp.34-34
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• 2003

Classical swine fever (CSF) is a contagious disease of swine with serious economic losses in pig industry [1]. The disease is caused by CSFV which belongs to the viruses of bovine viral diarrhea (BVDV) and border disease virus (BDV) make up the Pestivirus genus within the family Flaviviridae [2]. Attenuated Korean LOM strains were used in Korea. For these reasons a practical approach for discrimination between vaccine and field strains is needed. Here, we described the deveopment of real-time RT-PCR to discriminate between vaccine strains and Korean field viruses of CSFV. (omitted)

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2120-2122
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• 1999

$SF_6$ gas has been widely used the gas insulated transmission line, gas insulated transformer and gas insulated substation and Polyester film used as the turn insulation with other material. $SF_6$ gas has been actively studied in domestic and foreign countries. In general, when dielectric surface electric field exceed any electric field strength on air, corona discharge is occurred from the dielectric surface. This paper presents the insulation strength of turn insulation of $SF_6$-PET film studied under application of AC voltage, constitute of the plane to plane with PET Film. The results obtained in experimental are summarized that Partial Discharge Initial Voltage(PDIV) of turn insulation depend on gas pressure, but Breakdown Voltage(BDV) did not depend on gas pressure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.216-216
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• 2009

This paper describes a novel processing technique for the fabrication of polymer-derived SiCN (silicone carbonitride) microstructures for extreme microelectromechanical system (MEMS) applications. A polydimethylsiloxane (PDMS) mold was formed on an SU-8 pattern using a standard UV photolithographic process. Next, the liquid precursor, polysilazane, was injected into the PDMS mold to fabricate free-standing SiCN microstructures. Finally, the solid polymer SiCN microstructure was cross-linked using hot isostatic pressure at $400^{\circ}C$ and 205 bar. The optimal pyrolysis and annealing conditions to form a ceramic microstructure capable of withstanding temperatures over $1400^{\circ}C$ were determined. Using the optimal process conditions, the fabricated SiCN ceramic microstructure possessed excellent characteristics includingshear strength (15.2 N), insulation resistance ($2.163{\times}10^{14}\;{\Omega}$, and BDV (1.2 kV, minimum). Since the fabricated ceramic SiCN microstructure has improved electrical and physical characteristics compared to bulk Si wafers, it may be applied to harsh environments and high-power MEMS applications such as heat exchangers and combustion chambers.