http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
브리지 및 원형 금 박막의 기계적 물성 및 계면파괴인성치 측정
최우성(W.S. Choi),최승태(S.T. Choi),손상욱(S.U. Son),이승섭(S.S. Lee),양세영(S.Y. Yang),엄윤용(Y.Y. Earmme) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In order to measure the mechanical properties of gold films on Si substrate, two types of specimens, i.e., bridged films and circular membranes, are manufactured. Using the wedge tip, the bridged films are indented so that the bridged gold films are pushed off, which is called as V-peel test. The load-deflection curves obtained by the V-peel tests are analyzed with the concept of geometrically nonlinear beam by using the minimum potential energy theory together with Ritz method. Young’s modulus and residual stress of the bridged gold films are obtained. Blister test is also conducted to measure the Young’s modulus and residual stress of the circular membrane specimens, of which deformation is measured by Twyman-green interferometer. By gradually increasing the applied pressure in the blister test, the interfacial fracture toughness between the gold film and Si substrate is measured.
최우성(W.S. Choi),윤완노(W.N. Yun),강명수(M.S. Kang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
A gas turbine is called a combustion turbine and has an upstream compressor coupled to a downstream turbine, and a combustion chamber. Several cracks were oftenly observed at flange area between compressor casing and turbine casing in case of Westinghouse 501F series gas turbine. This component was made 1Cr1Mo0.25V steel such as conventional steam turbine casing. In this study, heat transfer and stress analysis using finite element analysis was performed in order to identify causes of flange cracking failure. Also, repairing method for effective maintenance was proposed.
최우성(W.S. Choi),김봉수(B.S. Kim),김범신(B.S. Kim),송기욱(G.W. Song) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Fossil power plants are requested to be more efficient and reliable for longer operation against frequent start-ups and load changes, recently. To aid utilities in this endeavor, various technologies have been developed that provide a systematic approach to life assessment of critical facilities. Steam turbine facilities such as turbine rotor, inner casing, especially, may suffer from more severe creep and fatigue damage under high temperature and high pressure conditions. However, until now, to evaluate remaining life of turbine facilities, qualitative / semi-quantitative analysis is carried out without standard guideline or procedure in Korea. In this paper, the procedure for assessing the life consumption of turbine facilities is proposed based on creep and fatigue, generally accepted as dominant damage mechanisms of turbine facilities. According to the standard procedure, more reliable life assessment of turbine facilities and more effective maintenance can be possible.
(Glycine+Urea) 혼합연료를 이요한 자발착화 연소반응법에 의한 우수한 소결성의 초미분체 LaAlO$_3$ 분말 합성
남희동,최우성,이병하,박성,Nam, H.D.,Choi, W.S.,Lee, B.H.,Park, S. 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.2
Si 기판위에 Ba2YCu3O7-$\delta$ 고온초전도체를 응용하기 위해 요구되는 buffer층으로 유망한 재료인 LaAlO3 단일상 분말을 고상반응법과 자발착한 연소반응법으로 제조하였다. 제조된 LaAlO3 분말의 입자형태와 결정상태는 scanning electron microscope (SEM)과 X-ray diffractometer (XRD)를 이용하여 분석하였다. 분말의 비표면적과 소결특성은 각각 Brunauer-Emmett-Teller(BET) 방법과 dilatometer를 측정하였다. 고상반응법으로 LaAlO3 분말을 제조할 때에는 하소온도를 150$0^{\circ}C$까지 높게 하여도 단일상을 얻는 것이 어려웠으나 자발착한 연소반응법에 의한 분말제조는 $650^{\circ}C$의 저온에서 하소하여도 쉽게 얻을 수 있었다. Dilatometer 측정을 통하여 분석해 보면, 고상반응법에 의한 분말보다 자발착한 연소반응법에 의한 분말로 제조된 소결체가 고상반응법에 의한 소결체에 비해 1.4배나 큰 소멸밀도(98.87%)를 가졌다. 이렇게 소결밀도에서 큰 차이가 나는 것은 자발착한 연소방법에 의한 분말의 평균 입자크기가 nano crystal size이고 비표면적 값(56.54 $m^2$/g)이 매우 크기 때문이다. 두가지 방법으로 제조된 분말을 이용, LaAlO3 layer를 스크린 프린팅과 소결법으로 Si 기판상에 제조하였으며 자발착한 연소합성법으로 제조된 분말은 110$0^{\circ}C$에서 우수한 소결특성을 나타내었다. LaAlO3d single phase used as the butter layer on Si wafer for YBa2Cu3O7-$\delta$ superconductor application were prepared by solid state reaction method and by self-sustaining combustion process. The microstructure and crystallity of synthesiszed LaAlO3 powder studied using scanning electron microscope (SEM) and X-ray diffractometer(XRD), specific surface area and sintering characteristics fo powder were investigated by Brunauer-Emmett-Teller (BET) method and dilatometer respectively. In solid state reaction method, it is difficult to obtain LaAlO3 single phase up to 150$0^{\circ}C$ period. However, in self-sustaining combustion process, it is to easy to do it only $650^{\circ}C$. Based on the results of analysis of dilatometer it is easier to obtain high sintering density (98.87%) in self-sustaining combustion process than in the solid state reaction method. This reason is that the average particle size prepared by self-sustaining combustion process is nano crystal size and has high specific surface are value(56.54 $m^2$/g) compared with that by solid state reaction method. Also, LaAlO3 layer on the Si wafer has been achieved by screen printing and sintering method. Even though the sintering temperature is 130$0^{\circ}C$, the phenomena of silicon out diffusion in LaAlO3/Si interphase are not observed.
조봉균,박해윤,홍진수,이광훈,안성기,최우성,김연희,채희백 순천향대학교 기초과학연구소 2000 순천향자연과학연구 논문집 Vol.6 No.1
A new method was suggested to deduce the optical parameters and its thickness of weakly absorbing thin film, on a transparent substrate, deposited by pulsed laser deposition technique. Those quantities can be calculated by considering in-situ laser reflectometry, transmission and reflection spectra. This new method becomes more goner질 and can be applied widely to many types of films. Its typical characteristics are as followings ; (1) Normal incidence of light with respect to films is not necessary, (2) Even multiple absorbing films can be treated in this way, and (3) It can be applied to analyze the optical properties of magnetic films and anisotropic films with a little modification of the theory.