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고출력 레이저에 의한 이종금속 용접시험평가에 관한 연구
유영태,신호준,송성욱,모양우 朝鮮大學校 機械技術硏究所 2004 機械技術硏究 Vol.7 No.1
Laser welding techniques have been characterised for various materials. In this paper. the laser weldability of STS304 stainless steel and Inconel 600 at dissimilar metal welds using a continuous wave Nd:YAG laser are experimentally investigated. Inconel 600 is being used in a steam generator tubing of pressurized water reactor(PWR) exposed to some corrosion. Stress corrosion cracking can occur on this material. An experimental study was conducted to determine effects of welding parameters, on eliminating or reducing the extent welding zone formation at dissimilar metal welds and to optimize those parameters that have the most influence parameters such as focus length, power, beam speed, shielding gas, and wave length of laser were tested.
고출력 레이저를 이용한 인코넬 600 합금의 용접 특성 연구
송성욱,유영태,신호준 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
The laser welding process is one of the most advanced manufacuring technologies owing to its high speed and deep penetration. Welding characteristics of Inconel 600 Alloy using a continuous wave Nd:YAG laser are experimentally investigated. The major process parameters studied in the present laser welding experiment were position of focus, laser power, travel speed. The gap and offset maintained as small as possible. Optical microscope were used to investigate the microstructures of the welded zone. The follow conclusions can be drawn the laser power and travel speed have a pronounced effect the fusion zone size and shape.
Escherichia coli 패혈증 환자에 합병된 대칭적 하지 말단 괴사증 1예
남해성,유진홍,권순석,민준기,조현선,박민경,심병주,남유정,이지인,김진수,길욱현,조근종,신완식 대한감염학회 2005 감염과 화학요법 Vol.37 No.6
We have encountered a rare case of symmetrical peripheral gangrene complicating Escherichia coli sepsis in a 47-years-old male. He was successfully treated with antibiotics, anticoagulants, and vasodilator. To our knowledge, this is the first report on symmetrical peripheral gangrene complicating E. coli sepsis in Korea.
연속파형 Nd:YAG 레이저에 의한 인코넬 600의 용접 공정변수의 연구
배신철,유영태,송성욱,신호준,나기대 朝鮮大學校 機械技術硏究所 2004 機械技術硏究 Vol.7 No.1
The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. Welding characteristics of Inconel 600 Alloy using a continuous wave Nd:YAG laser are experimentally investigated. The major process parameters studied in the present laser welding experiment were position of focus, laser power, travel speed. The gap and offset maintained as small as possible. Optical microscope were used to investigate the microstructures of the welded zone. The follow conclusions can be drawn the laser power and travel speed have a pronounced effect the fusion zone size and shape.
CuBr 반도체 양자구슬에서의 Hole Burning 현상
박지호,박성욱,김일곤,유동선 昌原大學校 基礎科學硏究所 2002 基礎科學硏究所論文集 Vol.14 No.-
PSHB spectrum was measured by the pump-probe method. After the absorption band of the nanocrystals sample was excited by the spectrally narrow band light, the spectral hole was produced at the position of the exciting light. The depth of spectral holes(main hole and side hole) was decreased with the temporal change. The energy difference between the zero phonon line and side hole depends on the radius of nanocrystals.
박춘식,장정욱,유기재,최성민 國立 昌原大學校 産業技術硏究所 2002 産技硏論文集 Vol.16 No.-
This Study investigated a possibility of lateral movement in the reconstruction field of Nongso bridge at Nongso-ri, Joochon-myeon, Kimhae. The methods applied in this study were the judgement formula and the Finite Element Method(FEM). The conclusions are shown in the following. 1) The application of the FEM, as well as the judgement formula resulted in the lateral movement. 2) Bridge abutment and foundation must be constructed after completing consolidation. 3) The occurrence possibility of lateral movement should be judged by the FEM that can re-present field conditions. 4) Lateral movement will take place in the case. Hence, settlement of proper countermeasure method should be followed by the construction.
김정호,조성욱,유봉준 중앙대학교 생산공학연구소 1999 생산공학연구소 논문집 Vol.8 No.1
대형구조물의 용접시 잔류변형과 잔류응력은 구 구조물의 모양과 크기, 그리고 구속조건에 따라 크게 달라진다. 따라서, 대형구조물의 잔류응력에 대한 정확한 해석을 위해 용접 잔류응력 및 용접 잔류변형을 정확히 예측할 수 있는 적절한 유한요소해석 절차의구현이 필요하다. 본 연구에서는 용접 잔류응력과 변형률의 존재를 예측할 수 있는 열전달 해석 및 열탄소성 해석과 같은 적절한 유한요소해석 과정을 찾고자 한다. 해석을 위해 아크의 열원에 대한 가우시안 분포를 가정하고 용접부의 상변화에 대한 엔탈피모델을 선정한다. 그리고, 대형구조물의 열전달해석을 위해 Remeshing기법을 이용한 유한요소모델의 생성이 필요하다. 끝으로, 개발된 해석과정은 단순맞대기 용접에 대해 적용해 보았고, Remeshing 기법은 컴퓨터 자원에 대한 절약 측면에서 상당한 효과를 나타내었다. Welded structures experience changes in shape, size and constraint conditions after favirication due to internal residual stresses. For the accurate simulation of the typical welding procedure, transient heat transfer analysis as well as thermal-elasti-plastec analysis should be employed. In this paper, appropriate finite element analysis procedures that can predict welding residual stresses and strains are presented. Gaussian distribution of arc heat source is assumed andenthalpy model is employed for phase change of the welding zone. Finally for the purpose of applying the developed technique to large scale structrues, remeshing techniques by successive generation of finite element model are given for that transfer analysis. The developed analysis procedure are tested for the simple butt welding which gives reliable results. Remeshing techniques are also tested against the existing mesh pattern which showed considerable reduction in computational resources.