다중사고의 고장전류 해석연구 ( Simultaneous Fault Current Analysis )

오용택,문영현 대한전자공학회 1987 대한전자공학회 학술대회 Vol.1987 No.7

Bi₂Sr₂Ca_2.2CuO₃O_x계에서 초전도상과 Bi-free상의 핵생성과 성장

오용택,신동찬,구재본,이인환,한상철,성태현 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.4

Using Bi$_2$Sr$_2$Ca$_2$.$_2$Cu$_3$ $O_{x}$ powders prepared by solid state reaction and spray drying method, the nucleation and growth behaviors of superconducting and second phases were investigated during isothermal heat treatment. When the spray drying power was used in contrast with solid state reaction powder, Bi$_2$Sr$_2$Ca$_2$.$_2$Cu$_3$ $O_{x}$ (2223) phase could be formed at the relatively shot time and second phases were much bigger. Quantitative analysis showed that as the heat treatment time increased, more Bi$_2$Sr$_2$Ca$_2$.$_2$Cu$_3$ $O_{x}$ (2212) changed to 2223 and the major second phase was changed from (Sr,Ca)$_{14}$Cu$_{24}$ $O_{x}$(14:24) to (Sr,Ca)$_2$Cu$_1$ $O_{x}$ (2:l). The superconducting phase formed at the relatively short time 14:24 phase. Following the Bi-free phase of 14:24 Phase, but long time was needed in places far from the 14:24 phase. Following the formation of the 2212 phase near the 14:24 phase, the 2223 phase nucleated preferentially at the interface between the 2212 and 14:24 phases. The preferential nuclcation of 2223 was explained by its structural similarity and low Interfacial energy with both the Bi-free and 2212 Phases.12 Phases.

기판의 접촉각과 분말량이 자기조립을 통해 형성된 SiO₂ 광자결정의 광특성에 미치는 영향

오용택,김명순,신동찬,O, Yong-Taeg,Kim, Myung-Soon,Shin, Dong-Chan 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.7

This study investigated the effects of the substrate and powder content on the fabrication of SiO$_{2}$ photonic crystals by evaporation method. Photonic crystals were self-assembled on quartz, Corning 1737 glass, slide glass, and ITa glass to verify the effects of the wetting angle and surface morphology. The powder contents of the solution were varied from 0.2 to 2.0 wt$\%$. The number of photonic crystal layers increased according to the decrease of wetting angle and surface roughness. The resultant photonic crystals showed the best optical characteristics when the number of photonic crystal layers was within 40 and 50. In addition, the intensity peak of Fabry¡?Perot fringes increased when the wetting angle was large and the particle size was small. Photonic crystals coated on ITO glass showed the highest reflectance peak of 63$\%$ relative intensity.

자기조립을 통해 형성된 실리카 광자결정의 광특성에 미치는 기판의 영향

오용택,신동찬 조선대학교 생산기술연구소 2005 生産技術硏究 Vol.27 No.spec

We investigated the effect of substrate on the fabrication of SiO_(2) photonic crystal by evaporation method. Monodispersed SiO_(2) nanopaticles were fabricated through the Stober process. The nanoparticles were self-assembled on quartz, corning 1737 glass, slide glass, ITO glass at vacuum oven by evaporation method. When the wetting angle increased the thickness of photonic crystal decreased. The peak intensity of reflectance had maximum value on the ITO glass (61%), which had highest wetting angle. We could obtain best optical properties through the control of wetting angle and particle contents.

발전기 보호 계전기 동작 사례 조사

오용택,양정재,박철원 대한전기학회 2013 전기의 세계 Vol.62 No.1

REBa₂Cu₃O_(7-X) (RE=Nd, Gd, Dy) 초전도체의 열처리에 따른 상변태와 미세구조

오용택,신동찬 조선대학교 생산기술연구소 2003 生産技術硏究 Vol.25 No.2

This study investigated the phase transformation of the REBa₂Cu₃O_(7-x) (RE = Nd, Gd, Dy) superconductor, and CCT (Continuous-Cooling-Transformation) along with the TTT (Time- Temperature-Transformation) diagrams are suggested according to the isothermal and continuous cooling heat-treatments. The peritectic temperature of the RE-123 phases approximately decreased to 30℃ when the ionic radius of the rare-earth elements was reduced. The optimum cooling rate, where BC and Cu-free phases do not exist, was 0.001℃/s. At this cooling rate, the RE-123 phase grew with a c-axis perpendicular to the surface and had a well-distributed RE-211 phase. When the oxygen partial pressure was reduced during isothermal heat-treatment. the formation temperature of the RE-211 phase decreased. In addition, the formation temperature of the RE-123 phases decreased from l000℃ (Nd-123) to 925℃ (Gd-123), and finally 875℃ (Dy-123) according to the decrease in the ionic radius of the rare-earth elements. Compared to Nd-123, Gd- and Dy-123 had a better texture with a well-distributed RE-211 phase.

Bi₂Sr₂Ca₂.₂O_(X)계에서 초전도상의 핵생성과 성장

오용택,신동찬 조선대학교 생산기술연구소 2003 生産技術硏究 Vol.25 No.2

Using Bi₂Sr₂Ca₂.₂Cu₃0x powders prepared by solid state reaction and spray drying method, the nucleation and growth behaviors of superconducting and second phases were investigated during isothermal heat treatment. When the spray drying power was used in contrast with solid state reaction powder. Bi₂Sr₂Ca₂Cu₃0x (2223) phase could be formed at the relatively short time and second phases were much bigger. Quantitative analysis showed that as the heat-treatment time increased, more Bi₂Sr₂Ca₁Cu₂0x (2212) changed to 2223 and the major second phase was changed from (Sr,Ca)₁₄Cu₂₄0x (14:24) to (Sr,Ca)₂Cu₁ (2:1). The superconducting phase formed at the relatively short time of 20 h around the Bi-free phase of 14:24 phase, but long time was needed in places far from the 14:24 phase. Following the formation of the 2212 phase near the 14:24 phase, the 2223 phase nucleated preferentially at the interface between the 2212 and 14:24 phases. The preferential nucleation of 2223 was explained by its structural similarity and low interfacial energy with both the Bi-free and 2212 phases.

REBa2Cu3O7-x (RE=Nd, Gd, Dy) 초전도체의 열처리에 따른 상변태와 미세구조

오용택,한용희,한병성,한상철,성태현,홍광준,신동찬 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.12S

This study investigated the phase transformation of the REBa2Cu3O7-x (RE=Nd, Gd, Dy) superconductor, and CCT (Continuous-Cooling-Transformation) along with the TTT (Time-Temperature-Transformation) diagrams are suggested according to the isothermal and continuous cooling heat-treatments. The peritectic temperature of the 123 phases decreased approximately 30oC when the ionic radius of the rare-earth elements was reduced. The optimum cooling rate where BC and Cu-free phases do not exist was 0.001oC/s. At this cooling rate, the 123 phase grew with a c-axis perpendicular to the surface and had a well-distributed 211 phase. When the oxygen partial pressure was reduced during isothermal heat-treatment, the formation temperature of the 211 phase decreased. In addition, the formation temperature of the 123 phases decreased from 1000oC (Nd-123) to 925oC (Gd-123), and finally 875oC (Dy-123) according to the decrease in the ionic radius of the rare-earth elements. Compared to Nd-123, Gd- and Dy-123 had a better texture with a well-distributed 211 phase.

자기조립을 통해 형성된 실리카 광자결정의 광특성에 미치는 열처리 효과

오용택,김명순,신동찬,O, Yong-Taeg,Kim, Myung-Soon,Shin, Dong-Chan 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2

열처리가 단분산 구형 $SiO_2$ 나노 분말의 자기조립을 통하여 형성된 광자결정 박막의 광특성에 미치는 영향에 대하여 조사하였다. 광밴드갭에 의해 나타나는 반사율 피크는 열처리 온도가 증가함에 따라 단파장 쪽으로 이동하였고, 빛의 회절에 의해 나타나는 Fabry-Perot fringes 피크의 강도도 증가하였다. 또한, 반사율의 절대값도 $250\~300^{\circ}C$ 사이에서 열처리한 시편에서 가장 높은 값을 나타내었다. 미세구조 분석에 따르면 저온열처리를 통하여 입자크기와 결함량이 줄어들고 결정의 치밀도는 증가하였다. We examined the effect of low temperature heat-treatment on the optical properties of the photonic crystals self-assembled using a monodispersed spherical $SiO_2$ nanoparticle. When the heat treatment temperature increased, the reflectance peak, which is induced by the photonic band gap, moved to a shorter wavelength direction, and the peak intensity of Fabry-Perot fringes also increased. The highest reflectance peak intensity was obtained in the sample heat-treated at $250\~300^{\circ}C$. The heat-treatment reduced the average particle size and the quantity of defects, and increased the packing density of the photonic crystal.

전력계통의 모선분할에 대한 단락용량 해석방법 연구

오용택 韓國技術敎育大學校 1995 論文集 Vol.2 No.1

Short circuit analysis is one of the most fundamental procedures for power system analysis problem. The problem related to short circuit studies should be requested greater interest to the future, especially in terms of power system availability and reliability. In order to solve the problem, it's required to develop an advanced algorithm by which short circuit currents are easily computed for a large number of alternative network configurations at main substation. This paper proposes a new calculation method to efficiently modify the bus impedance matrix elements to short circuit studies for bus separation in large power system by method of addition and removal of dummy link, and presents its practicality by applying the proposed method to the calculation short circuit analysis in the power system model.