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부분방전을 이용한 초고압 지중 송전 절연 케이블 내부 결함의 패턴분석
박재화(Jae-Hwa Park),이광열(Kwang-Yeol Lee),채석(Seog Choe),오영석(Young-Seong Oh),김학성(Hack-Sung Kim) 전력전자학회 1998 전력전자학술대회 논문집 Vol.- No.-
The insulation of cables which used for Ultra-High Voltage (UHV) underground power transmission requires excellent insulation capability for high voltage. The typical insulation materials are used XLPE. EPR, etc, but insulation efficiency of these is affected by void or alien substances, existed at the inside of insulators. In this paper, the partial discharge patterns of the defects within insulation cable are observed and analyzed. In this test, void, fiber and metal inclusions which possibly exist in cables, are simulated and investigated the patterns of partial discharges for each models Also the relations between calculated field strength and the insulation breakdown voltage. The experiment shows distinct partial discharge patterns in accordance with the kinds of defects within Insulation cable.<br/> <br/>
Cl-based 플라즈마에 의한 YMnO<sub>3</sub> 박막의 식각 damage에 관한 연구
박재화,기경태,김동표,김창일,장의구 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.6
Ferroelectric YMnO$_3$ thin films were etched with Ar/Cl$_2$ and CF$_4$/Cl$_2$ inductively coupled plasma (ICP). The maximum etch rate of YMnO$_3$ thin film was 300 $\AA$/min at a Ar/Cl$_2$ gas mixing ratio of 2/8, a RF power of 800 W, a DE bias of 200 V, a chamber pressure of 15 mTorr, and a substrate temperature of 30 $^{\circ}C$. From the X-ray photoelectron spectroscopy (XPS) analysis, yttrium etched by chemical reactions with Cl radicals assisted by Ar ion bombardments in Ar/Cl$_2$ plasma. In CF$_4$/Cl$_2$ plasma, yttrium are remained on the etched surface of YMnO$_3$ and formed of nonvolatile YF$_{x}$ compounds manganese etched effectively by chemical reactions with Cl and F radicals. From the X-ray diffraction (XRD) analysis, the (0004) diffraction peak intensity of the YMnO$_3$ thin film etched in Ar/Cl$_2$ plasma shows lower value than that in CF$_4$/Cl$_2$ plasma. It indicates that the crystallinty of YMnO$_3$ thin film is more easily damaged by the Ar ion bombardment than the changes of stoichiometry due to nonvolatile etch by-products.s.
HVPE 법에서의 공정변수 조절에 의한 bulk GaN 단결정의 두께 최적화
박재화,이희애,이주형,박철우,이정훈,강효상,강석현,방신영,이성국,심광보,Park, Jae Hwa,Lee, Hee Ae,Lee, Joo Hyung,Park, Cheol Woo,Lee, Jung Hun,Kang, Hyo Sang,Kang, Suk Hyun,Bang, Sin Young,Lee, Seong Kuk,Shim, Kwang Bo 한국결정성장학회 2017 韓國結晶成長學會誌 Vol.27 No.2
다양한 성장온도, V/III 비율, 성장속도과 같은 공정변수의 조절을 통하여 GaN 단결정을 성장시키고, 그에 따른 표면 및 재료 내부의 결함분석을 통하여 고휘도 고출력의 소자적용을 위한 bulk GaN 단결정의 두께를 최적화하였다. 2인치 직경의 sapphire 기판 위에 HVPE(hydride vapor phase epitaxy) 공정변수들을 조절하여, 0.3~7.0 mm 두께의 GaN 결정을 성장시켰다. 성장된 GaN 단결정의 구조분석을 위하여 XRD 분석을 사용하였고, 공정변수의 변화에 따른 표면 특성은 광학 현미경을 이용하여 관찰하였다. 성장된 두께에 따른 결함밀도 분석을 위하여 화학습식 에칭하였고, 에칭된 표면을 SEM으로 관찰하였다. GaN single crystals were grown by controlling of various processing parameters such as growing temperature, V/III ratio and growing rate. We optimized thickness of bulk GaN single crystal by analyzing defect of surface and inside of the GaN single crystal for application to high brightness and power device. 2-inch bulk GaN single crystals were grown by HVPE (hydride vapor phase epitaxy) on sapphire and their thickness was 0.3~7.0 mm. Crystal structure of the grown bulk GaN was analyzed by XRD (X-ray diffraction). The surface characteristics of the grown bulk GaN were observed by OM (optical microscope) and SEM (scanning electron microscopy) with measuring EPD (etch pits density) of the GaN crystals.