• 한국해양공학회지
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• 제30권4호
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• pp.334-340
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• 2016

The combustion chamber of a diesel engine is often exposed to a more serious wear and corrosion environment than other parts of the engine because its temperature increases as a result of using heavy oil of low quality. Therefore, repair and built-up welding methods must be performed on worn or corroded parts of the piston crown, exhaust valve, etc. from an economical point of view. In this study, Inconel 718 filler metal was used in repair welding on the groove of a forged steel specimen for a piston crown, along with built-up welding on the surface of another forged steel specimen. Then, the corrosion characteristics of the weld metal zone for the repair welding and the deposited metal zone for the built-up welding were investigated using electrochemical methods in a 35% H₂SO₄ solution. The deposited metal zone indicated better corrosion resistance than the weld metal zone, showing a nobler corrosion potential, higher impedance, and smaller corrosion current density. It is considered that metal elements with good corrosion resistance were generally included in the filler metal, and these elements were also greatly involved in the deposited meta by built-up welding, whereas the weld metal consisted of metal elements mixed with both the filler metal and base metal elements because of the molten pool produced by the repair welding. Finally, it is considered that the hardness of the weld metal was increased by the repair welding, whereas the built-up welding improved the corrosion resistance of the deposited metal.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.4-5
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• 2021

In irregular curtain walls, the nominal stress required for each member varies greatly depending on the shape, so it is inefficient to design members based on the maximum required stress. Then, built-up members are absolutely necessary, but built-up members manufactured by Manpower-welding cannot be constructed in an irregular curtain wall building because it' not precise. In order to address the problems, this paper presents why Robotic-laser-welding should be used in irregular curtain walls using Gwanggyo Galleria Department Store involving 3D printing as an example. Results verify the performance of Robot-Laser-Welding as an efficient solution for precise steel curtain wall members.

• Steel and Composite Structures
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• 제10권3호
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• pp.261-279
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• 2010

Generally, a box tube, which is used for an existing square CFT structure, is made by welding four plates. The manufacturing efficiency of this steel tube is poor, and it also needs special welding technology to weld its internal diaphragm and the through diaphragm. Therefore, an interior-anchor-type square steel tube was developed using the method of cold-forming thin plates to prevent welding of the stress concentration position, and to maximize the section efficiency. And, considering of the flow of beam flange load, the efficiency of erection and the weldability of the diaphragm to thin walled steel column, the external diaphragm connection was selected as the suitable type for the welded built-up square CFT column to beam connection. And, an analytical study and tests were conducted to evaluate the structural performance of the suggested connection details and to verify the suggested equations for the connection details. Through this study, the composite effect of the internal anchor to concrete, the resistance and stress distribution of the connections before and after the existing column is welded to the beam, the effective location of welding in connection were analyzed.

• 한국해양공학회지
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• 제5권1호
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• pp.97-105
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• 1991

In this paper, the fatigue strength and the fatigue crack propagation behaviors of the round bar specimens which were spirally built up by welding and subsequently hardened by quenching were investigated. The material used was SF60 which was whdely employed in mechanical components, especially shafts. Fatigue tests were conducted at the fully reversed condition(R=-1) and axial and load control in the room temperature ahd air environment. The experimental results were expressed by both the range of stress intensity factor ($\Delta{K}$) and the effective range of stress intensity factor ($\Delta{K}_{eff}$). It was clarified that applying of quenching after the building up welding process improved the fatigue strength and the gatigue crack propagation property in the low range of $\Delta{K}$ of the built up round bar specimen.

• 한국강구조학회 논문집
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• 제28권2호
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• pp.75-83
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• 2016

기존 콘크리트충전 각형강관(CFT) 구조에 사용하는 각형강관은 4개의 판을 용접하여 제작하는 박스칼럼이 일반적이다. 그러나 이러한 강관은 제작효율이 저하되며, 또한 기둥-보 접합부에는 내측 다이아프램과 관통 다이아프램을 용접하는데 특수한 용접기술이 필요하다. 따라서, 얇은 강판을 절곡하는 방식으로 응력집중 위치의 용접을 피하고, 단면효율이 극대화된 내부앵커 돌출형의 용접조립 각형강관을 개발하게 되었다. 용접조립 각형강관은 강관내부에 스티프너가 설치되어 내측 다이아프램과 관통 다이아프램과 간섭이 발생하게 되므로 본 연구에서는 용접조립 각형CFT 기둥-보 접합부로 외다이아프램형식을 채택하고 외다이아프램의 설계식을 제안하였으며, 기둥-보 접합부의 거동을 파악하기 위해 실대형 4개 실험체를 제작하여 구조거동 및 내력을 분석하였다.

• 대한조선학회논문집
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• 제33권1호
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• pp.206-213
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• 1996

용접에 의해 발생된 조립보의 종굽힘 변형은 다음 공정에서 판과 결합되기 위해서 교정되어야 한다. 변형의 교정은 숙련된 기능공들의 경험에 의한 곡직 가열을 통해 수행되고 있는데, 이 작업은 시행착오적 과정을 거치면서 이루어 지므로 상당한 공수가 소요된다. 본 연구에서는 가열에 의한 곡직 변형량을 추정할 수 있는 방법을 제시하고, 이 방법을 활용하여 용접 조립보의 생산 과정을 재현할 수 있는 시뮬레이션 방법을 개발함으로써, 조립보 제작 시의 생산성을 향상하고자 한다.

• 대한조선학회논문집
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• 제31권3호
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• pp.145-153
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• 1994

용접 조립보의 생산시에는 용접에 의해 종변형이 발생하여, 생산성 향상과 품질 향상의 장애 요인이 되고 있는데, 본 연구에서는 용접 조립보 생산 자동화의 기초가 되는 변형 제어를 위해 용접 변형을 간단한 식으로 예측할 수 있는 간이 열탄소성 해석 기법을 제안하고 실험을 통해 그 유용성을 입증하였다. 간이 열탄소성 해석을 통해 본 연구에서 정의한 변형 계수는 조립 변수의 함수임을 밝혔으며, 제시한 변형량 추정식은 조립보 생산 과정의 시뮬레이션시에 활용 될 수 있다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1995년도 특별강연 및 춘계학술발표 개요집
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• pp.137-138
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• 1995

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.285-287
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• 2004

최근 굴삭기의 대형화 및 고성능화 그리고, 내구성의 향상과 함께 다양한 작업 조건에 효율적인 운전 특성을 확보하기 위한 작업 장치의 구조 형상 최적화를 위한 많은 연구가 수행되고 있다［1,2］. (중략)

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.238-246
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• 2001

Residual stresses and thermal deformation of a structure due to welding are very imfortant factors for a weld design. It has been carried therretical analysis to invesitigate influence of heat flux to residual stresses and thermal deformation producted by curcumferential welding. Temperature,stresses and deformationn are obtain as a function of circumferentisl drgree and distance from welding center line. These result can applicate to predict and remove the deformation or residual stresses built up by welding.