• Journal of Welding and Joining
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• 제10권4호
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• pp.181-189
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• 1992

The purpose of this investigation is to examine the effects of the strengthening treatments on the mechanical properties of the flame-sprayed titania ceramic coating layer. The strengthening treatments for flame sprayed specimens were carried out in 12 different conditions in vaccum furance. The mechanical properties such as microhardness, thermal shock resistance, adhesive strength and erosion resistance were tested for the sprayed specimens after strengthening treatments. And it was clear that the mechanical properties of coating layer were much improved by the strengthening treatments. The results obtained are summarized as follows; 1. It was shown that the metallurgical bond was formed between substrate and coating layer by the strengthening treatments and that thermal shock resistance and adhesive strength were remarkably raised. 2. Microhardness of coating lay was considerably increased by the strengthening treatments. 3. Erosion resistance and porosity of coating layer were slightly improved by the strengthening treatments.

• Journal of Welding and Joining
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• 제34권5호
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• pp.1-5
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• 2016

The hardness of laser weldments has been predicted by using several carbon equivalent equations and estimation models. In this study, authors extended the model to boron steel sheets which are adopted for the hot press forming process. four kinds of boron steels with the strengths from 1500 MPa to 1900 MPa were considered and the hardness profiles of weldments was measured from the experiments of this study and the references. The traditional "Kaizu" equation could predict the hardness with an accuracy of -4.9% error although the Kaizu equation does not consider the boron content. Modified carbon equivalents were suggested by adding a term as like 5B or 14B into the Kaizu equation, and it could improve the accuracy of the prediction model.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.257-265
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• 2009

본 논문에서는 2차유동손실을 일으키는 주요 요인 중의 하나인 말굽와류의 강도를 감쇄시키기 위해 일반적인 날개 앞전의 형상을 결정하는 변수를 정하고 이를 최적화 하였다. 근사최적설계 기법을 이용최적화를 수행하였다. 유동해석과 최적화 프로그램으로는 $FLUENT^{TM}$과 $iSIGHT^{TM}$를 이용하였다. 최적화 수행결과, 기준 모델의 경우보다 전압력 계수가 약 9.79% 감소하였다.

• 소성∙가공
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• 제12권3호
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• pp.214-220
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• 2003

In the case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. There have been few studies about condenser tube extruded by porthole die. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to variation of chamber length in porthole die. The welding chamber height in condenser tube was calculated by using finite element method. Forming analysis results for condenser tube would provide useful information for the optimal design of porthole die.

• Journal of Welding and Joining
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• 제6권1호
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• pp.46-52
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• 1988

Retardation or delay in fatigue crack growth due to overloads are important for the accurate prediction of fatigue lives of structural materials. In this study, retardation of fatigue crack growth in Al 6061-T6 weldments and heat affected zones (HAZ) after single overload cycle had been investigated. Retardation in both weldments and HAZ was observed. It was concluded that retardation in both weldment and HAZ was greater than in base metal due to microstructural change and crack branching and crack closure were major governing factor in retardation.

• Journal of Welding and Joining
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• 제9권3호
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• pp.18-25
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• 1991

The purpose of this paper was to investigate the effect of deposition configuration on the mechanical properties of the flame sprayed titania ceramic coating. The sprayed deposition configuration was made in different five types with titania ceramic and Ni-base alloy on the mild steel substrate. The composite coating exhibited superior mechanical properties such as hardness, adhesive strength, thermal shock resistance and corrosion resistance, whereas the mixed coating proved to be more resistant to erosion. Especially graded coating, which consist of Ni-base alloy undercost, intermediate grade coat and titania ceramic overcost, showed excellent mechanical properties.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.213-216
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• 2005

A numerical analysis was performed for interior connections of continuous flat plate to analyze the effect of design parameters such as column section shape, gravity load and slab span on the behavioral characteristics of the connections. Through the parametric study, the variations of shear stress distribution around the connection were investigated. According to the result of numerical analysis, as the length of the cross section of column in the direction of lateral load increases and gravity load increases, the effective area and the maximum shear strength providing the torsional resistance decrease considerably. And as the slab span loaded with relatively large gravity load increases, the negative moment around the connection increases and therefore the strength of connection against unbalanced moment decreases.

• 한국세라믹학회지
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• 제33권3호
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• pp.251-258
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• 1996

The reactions between an active metal brazing alloy and interlayers together with the effects of interlayer type on the interfacial microstructure change were investiaged for silicon nitride/stainless steel joint. The bending strengths were measured for joints with Mo, Cu, Ni interlayer type of different thicknesses. It was found that the interlayer with a low yield strength value is effective to improve the bending strength of the Si3N4/stainless steel joint. The maximum joint strength obtained at room temperature for a laminated Cu/Mo interlayer was about 460 MPa. The combined use of Mo and thin Cu layer was found to be effective in enhancing the bending strength for the Si3N4/S.S.316 joint.

• 기계저널
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• 제43권8호
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• pp.32-43
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• 2003

2002년도 재료 및 파괴부문의 연구는 예년에 비해 더욱 활성화되었다. 부문 학술대회에서 효율적인 학술토의 및 아이디어 교환을 위해 기획 세션을 구성하여 대회를 운영하였으며, 기획 세션의 종료 및 세션 조직위원으로 활동한 회원은 다음과 가다. CAE/피로설계(이영신, MSC Korea), 신소재 및 복합재료(한경섭, 포항공대), 접합부의 강도평가(남기우, 부경대), 신뢰성 평가(진태은, 한전기술), 구조물의 손상평가(신병천, KIMM), NDT 기법 응용(윤동진, 표준연), 전자패키징 신뢰서(이순복, KAIST), 계산역학(박재학, 충북대), 발전소요소 진단 및 평가(박윤원, 원자력안전기술원), RBI-FFS-IT(최지붕, 성균관대), NT 분야(박준협, 동명정보대), 에너지 및 화력발전분야(하정수, 전력연구원)이다. 본 연감의 내용도 위에 언급한 기획 세션 주제별로 나누어 활동 사항을 요약하였다. 일부 논문은 분야가 중복되기도 하지만 본 연감에서는 주요 세션에서만 언급하였으며, 지면 관계상 많은 우수한 연구 활동에 대해 적절히 언급되지 못한 면도 있음을 발혀둔다.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1835-1843
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• 2001

The energy release rate for an interface crack in anisotropic dissimilar materials was obtained by the eigenfunction expansion method and also was analyzed numerically by the reciprocal work contour integral method. It was shown that the results for orthotropic dissimilar materials are consistent with the other worker's results.