• 전기전자학회논문지
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• 제26권1호
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• pp.50-55
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• 2022

SiC는 차세대 전력반도체의 핵심 재료로 넓은 밴드갭과 높은 절연파괴강도, 열전도율을 가지고 있지만 deep level defect와 같은 다양한 문제를 야기하는 결함이 존재한다. SiC에서 나타나는 defect는 물성에서 나타나는 defect와 계면에서 나타나는 interface trap 2가지로 나뉜다. 본 논문은 상온 (300 K)에서 보고되는 Z_1/2 trap concentration 0 ~ 9×10¹⁴ cm^-3을 SiC substrate와 epi layer에 적용하여 turn-on 특성을 알아보고자 한다. 전류밀도와 SRH(Shockley-Read-Hall), Auger recombination을 통해 구조 내 재 결합률을 확인하였다. trap concentration이 증가할수록 turn-on시 전류밀도와 재 결합률은 감소하며 Ron은 0.004에서 0.022 mΩ으로 약 550% 증가하였다.

• 조명전기설비학회논문지
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• 제25권2호
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• pp.131-136
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• 2011

This paper aims to examine the possibility of using an environmentally friendly $N_2$ as an alternative gas to $SF_6$. For this purpose, we have investigated breakdown characteristics of $N_2$ under impulse voltages in a quasi-uniform electric field gap. The 1.2/50[${\mu}s$] lightning impulse voltage, switching impulse voltages and oscillatory impulse voltages were applied at the test gap. The electric field utilization factor ranges from 0.5 to 0.8. The experimental data of $SF_6$ and $N_2$ acquired in the same experimental condition are presented in parallel for comparison. As a result, the breakdown voltages in $SF_6$ and $N_2$ are linearly increased with the gas pressure, also the breakdown voltages in $N_2$ are increased with increasing the gap distance and electric field utilization factor. The positive breakdown voltages are higher than the negative breakdown voltages. The nagative basic lightning impulse withstand level of 150[kV] in $N_2$ of about 0.5[MPa] is nearly equal to that in $SF_6$ of 0.15[MPa]. It is seen from the results obtained in this work that $N_2$ can be used as an eco-friendly alternative gas to $SF_6$ in distribution power equipment.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.54-60
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• 2008

2002년부터 시행되어오고 있는 제조물 책임법에 의해 사고케이블의 원인분석과 사고패턴에 대한 데이터베이스화가 중요하다. 더욱이 가속열화상태에서 전력케이블 사고의 패턴 및 모의실험은 데이터베이스 시스템 구축에 필요하다. 본 논문에서는 열 열화 따른 22.9[kV]이하 케이블의 열 충격시험을 수행하였다. 이 시험은 IEC60811-3-1에 따른다. 시험결과로부터, 22.9[kV]급 A사 전력케이블은 표면이 변색되었고 길이방향으로 급격하게 감소되었다. 특히, A사 전력케이블의 열 중량 특성이 심하게 변함에 따라, 케이블 제조상의 문제일 것이라 추측된다. 만약 전력케이블의 제조상의 결함에 의한 것이라면, 피해자들은 PL환경 하에 손해배상을 받을 수 있을 것이다.

• 전기학회논문지
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• 제59권8호
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• pp.1416-1422
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• 2010

$SF_6$ is the most commonly used insulating gas in electrical systems. But In these days $SF_6$ mixtures and alternative gas has been studied because of global warming. so although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/N_2$ mixtures. At present study the breakdown characteristics of $SF_6/N_2$ mixtures in Non-uniform field was performed. In this paper, The simulation value are compared with experiment values. Streamer breakdown criterion was used for predicting breakdown voltage. For accurate simulation this simulation apply utilization factor using CST(computer simulation technology) EM $studio^{tm}$ program. AC breakdown experiments in non-uniform field was performed to compare with the breakdown simulation values. The pressure range of gas mixtures was 0.4 MPa to 0.7 MPa. The rod-plane was used and mixture ratio is $SF_6$ 20% : $N_2$ 80%. The gap lengths are 10mm to 70mm. As the pressure increase, this simulation value does not correspond to the experiment value. So this simulation need surface roughness factor. As a result of applying surface roughness factor this simulation decrease a relative error (|experiment value - simulation value| /simulation value).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1455_1456
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• 2009

$SF_6$ is the most commonly used insulating gas in electrical systems. But In these days $SF_6$ mixtures and alternative gas has been studied because of global warming. so although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/CF_4$ mixtures. At present study the breakdown characteristics of $SF_6/CF_4$ mixtures in quasi-uniform field was performed. This experiments were carried out under AC voltages. The rod-rod electrode was used with 5 mm gap distance. The mixture of $SF_6/CF_4$ containing 20%,50%,70% of $SF_6$ were compared with pure $SF_6$ and $CF_4$ gas and gas pressure ranged from 0.1 to 0.5 MPa. The show that the breakdown voltages of gas were linearly increased according to the pressure in quasi-uniform field. For breakdown vlotage values of $(E/P)_{crit}$ are important. Because If values of (E/P) is a little more than $(E/P)_{crit}$, electrons rapidly increase and streamer discharge gernerates. Through this experiments values of $(E/P)_{crit}$ are found to vary with the ratio of $SF_6/CF_4$ mixture according to the following relationship. $V_b=(E/P)_{crit}{\cdot}p{\cdot}d$

• 조명전기설비학회논문지
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• 제20권1호
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• pp.85-90
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• 2006

본 논문은 불평등 전계의 $SF_6/CO_2$혼합기체 중에서 전구방전특성에 대한 실험결과를 제시한다. 임펄스 전구방전 진전을 코로나 전류와 방전광 이미지의 측정으로 조사하였다. 정 부극성의 전구방전 진전메커니즘은 기본적으로 같았으며, 초기스트리머코로나는 침전극의 끝단에서 발단되어 계단상으로 진전하는 리더에 의해 시험갭을 교락시킨다. 정극성에서 리더펄스의 휴지시간은 부극성에서보다 매우 짧았다. 또한 부극성에서 초기스트리머코로나와 절연파괴사이의 시간간격은 정극성에서보다 매우 길게 나타났다. 정극성에서 방전채널경로는 임의적으로 나타났으며, 부극성에서 리더 채널은 정극성에서 보다 굵고 밝게 나타났다.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.49-57
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• 2015

This paper presents the discharge characteristics and economic feasibility of a Dry $Air/O_2$ and a $N_2/O_2$ mixture gas in order to review $SF_6$ alternative. From AC discharge experiment in an quasi-uniform field, it was found that the optimal $N_2/O_2$ mixing ratio which breakdown voltage and surface flashover voltage were the highest was 70/30 and that the pressure dependence on the breakdown voltage was higher than that of the surface flashover voltage in the Dry $Air/O_2$ and the $N_2/O_2$ mixture gas. The mixing ratio (70/30) and the tendency of the pressure dependence were described in detail based on physical factors (impact ionization coefficient, electron attachment coefficient, secondary electron emission coefficient) involved in discharge mechanism and a electron source, respectively. In addition, the performance insulation and the economic feasibility of the Dry $Air/O_2$ and the $N_2/O_2$ mixture gas were discussed so that Dry $Air/O_2$ mixture gaswas more suitable than $N_2/O_2$ mixture gas to the $SF_6$ alternative.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.593-596
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• 2001

In the previous work, the effect of blending with two kinds of low density polyethylene (LDPE) on physical and electrical properties have been investigated. From the results, blending with two kinds of LDPE was effective method on changing the morphology of LDPE and improving the high-field characteristics in high temperature region. Especially, it suggested that the F$\_$BImp/ was associated with the changes of the crystal size. In this work, the relationship between the morphology and the high-field characteristics of blended LDPE was discussed. In addition, the physical and electrical properties of blended LDPE with extrusion treatment were investigated. The two groups of specimen were prepared; Group 1 was prepared by passing 1 time through the extruder included in the film-blowing process, and Group 2 was prepared by passing 2 times through the extruder. From the relation between the crystal size which was perpendicular to the (020) plane and the F$\_$BImp/ of blended LDPE, it was confirmed that the F$\_$BImp/ was associated with the changes of crystal size due to the blending. Moreover, the F$\_$BImp/ of blended LDPE in Group 2 was higher than that of blended LDPE in Group 1. The crystal size of the (020) plane became smaller according to the extrusion treatment. These results suggest that the uniform distribution and dispersion of crystalline occurred due to the extrusion treatment and the morphological change due to the extrusion treatment influenced on the electrical properties of blended LDPE.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.229-236
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• 1998

Ferroelectric $Sr_xBi_yTa_2O_{9+\alpha}$/(0.7$\leqSr\leq1.0,\; 2.0\leqBi\leq2.6)$ solutions were prepared by MOD (Metalorganic Deposition) process. These solutions were made into thin films with thickness ranging from 1500~2000${\AA}$ by spin coating. The phase transformation of the SBT thin films by variation of annealing temperature and annealing time were observed using high temperature XRD and SEM. The crystallization and grain growth of SBT thin film were accomplished at $800^{\circ}C$ for 30 minutes after deposition of Pt top electrode by sputtering to prevent electrical breakdown. Ferroelectric properties of the SBT thin films were measured in the range of $\pm$3V\; and\; \pm5V$. The specimen with composition ratio of Sr/Bi/Ta (0.8/2.4/2.0) has the excellent ferroelectric properties ; $2P_r = 10.5,\; 13.2\muC/cm^2 \;at\; \pm3V\; and\; \pm5V$ respectively. Observing the post annealed Pt/SBT/Pt interface by SEM, it was found that Pt electrode sputtered on to the SBT thin film penetrated into the hollow on the SBT thin film, thus decreasing the effective insulation thickness. The effective insulation thickness recovered by post annealing, and this was confirmed by leakage current density measurement.

• 한국세라믹학회지
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• 제40권6호
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• pp.553-559
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• 2003

PDP(Plasma Display Panel) rib은 고정세의 패턴 설계 및 복잡, 다양한 공정으로 제조되고 있다. Rib은 PDP제조 공정 및 역할상 매우 중요한 부분의 하나이며 rib의 소결 정도는 cross-talk와 같은 현상을 방지하는 데에 중요한 역할을 한다. 저렴하고 높은 양산성을 가진 rib은 주로 스크린 프린팅법에 의해 제작되지만, 인쇄, 소성 등 일련의 제조 공정을 거친 후 얻어진 수백 $\mu\textrm{m}$ 미세규격의 격벽 소결체의 소결도를 정확히 평가하기는 쉽지 않다. 본 연구에서는 rib의 소결도를 직접적 판단할 수 있는 방법에 대한 연구의 일환으로서 주로 소결 말기에 나타나는 기공의 응집, 성장을 potentiostat로 기공에서의 절연 파괴, 전계 집중의 원리를 이용함으로서 소결도를 측정했다 이 측정값은 각 온도에서 열처리한 시편에 대한 밀도값과 유사한 경향성이 나타남을 확인할 수 있었다 개기공, 폐기공의 분포에 따라 예상될 수 있는 측정오차는 온도에 따른 미세구조의 변화를 수차례의 전자 현미경 관찰을 통해 확인, 검증하여 미세규격 rib 소결도의 판단을 전기화학적 방법으로 예측 가능하다는 것을 알 수 있었다.