• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.129-136
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• 2012

On this study, $CO_2$ gas, net of Ar gas, and mixed gas in solid wire(AWS ER 70S-6) and flux cored wire(AWS E71T-1) were used to weld on Mild steel(SS400). After the progress, the status changes of the welds in Mild steel(SS400) were investigated with compositional changes. For stable experiments, welding was conducted using the automatic feeder. Radiation testing, hardness testing, chemical composition analysis and penetrated cross-section were measured. Through these experiments, shapes of penetrated cross-section, chemical composition changes, and weld defects according to the variation of welding gas were known. Weld defects and weld cross-sectional shapes by the variation of the welding voltage were also detected.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.352-355
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• 2004

Inconel 625 is useful in variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{\circ}C$ to over $1090^{\circ}C$, in combination with good law- and high temperature mechanical strength. Rencently, this material is also used widely in offshore processing piping in order to extend the maintenance tenn and improve the quality of anti-corrosion. In general, high quality weldments for this material are readily produced by commonly used processes. Not all processes are applicable to this material group, Ni-alloys. Metallurgiad characterictics or the unavailability of matching, position or suitable welding processes. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. in this study, the weldability and weldment characteristics of inconel 625 are considered in FCAW weld associated with the several shielding gases($80\%Ar\;+\;20\%\;CO_2,\;50\%Ar\;+\;50\%\;CO_2,\;100\%\;CO_2$) in viewpoint of welding productivity.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.9-13
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• 2005

Inconel 625 is useful in variety of industrial applications because of the resistance to attack on various corrosive media at temperature from $200^{\circ}C$ to over $1090^{\circ}C$, in combination with good low and high temperature mechanical strength. Recently, this material is also used widely in offshore processing piping in order to extend the maintenance term and improvement the quality of anti-corrosion. In general, high quality weldments for this material are readily produced by commonly used processes. Not all processes are applicable to this material group, Ni-alloys. Metallurgical characteristics or the unavailability of matching, position or suitable welding process. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. In this study, the weldability and weldment characteristics(mechanical properties) of inconel 625 are considered in FCAW(Flux Cored Arc Welding) associated with the severial shielding gases($80%Ar+20%CO_2,\;50%Ar+50%CO_2,\;100%CO_2$) in viewpoint of welding productivity.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.3-3
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• 2009

선박의 건조과정에서 필수적으로 선체 외판에는 선박의 안전과 운항 및 정비 등에 필요한 정보를 나타내기 위해 다양한 종류의 마크 및 문자가 마킹되어진다. 하지만, 단순한 도장 작업만으로는 해상과 같은 부식 환경에서 마크 및 문자가 쉽게 지워지거나 손상되기 때문에 마크 및 문자를 용접 비드(welding bead)로 표시하거나 미리 절단된 강판(steel plate)을 수동으로 용접한 뒤 도장을 함으로써 마크 및 문자의 손상을 방지하고 있다. 이러한 문자마킹작업을 하기 위해서는 작업자가 수작업으로 기준선과 마크 및 문자의 위치를 먹줄 등을 이용하여 마킹을 하고, 해당 마크 및 문자의 템플렛(template)을 이용하여 펀칭을 실시한 후 수동으로 용접을 실시한다. 하지만, 수작업을 통한 선체외판 문자마킹 작업은 작업자의 기량에 따라 품질이 상이하여 품질 저하의 원인이 된다. 또한 대조립 및 탑재 단계에서 문자 마킹 작업시 수직자세의 용접을 요구함으로써 작업자가 안전사고에 노출되어 있으며, 선박의 각 단계별 주요 공정보다 작업시간이 길어져 전체 선박 건조공정을 지연시키는 문제점 등을 야기시킬 수 있다. 이러한 문제점들을 해결하기 위해 조선업계에서는 선체 외판의 마크 및 문자를 자동으로 용접할 수 있는 장치를 개발하기 위해 노력해왔으며, 몇몇 개발 사례가 보고되고 있다. 하지만, 그 실효성 부분에서는 아직까지 해결하지 못한 문제점들로 인해 현장 적용에는 어려움을 보이고 있다. 본 연구에서는 선박외판 문자 자동용접장치의 기능성뿐만 아니라 현업 적용성을 가장 우선적으로 고려하여 문자마킹장치(Marking Robot for Shipbuilding) 개발을 진행하였다. 우선, 적절한 용접 재료를 선정하기 위해서 솔리드 와이어(Solid Wire)와 플럭스 코어드 와이어(Flux Cored Wire)에 대한 비드온 용접(Bead-On Welding)을 아래보기자세와 수직자세에 대해서 실시하여 적절한 용접 조건을 설정하였다. 본 연구에서 개발된 문자마킹 자동용접장치는 3축으로 구성되어 있으며 각 축들을 분리할 수 있도록 개발하여 이동성을 향상시켰으며, 작업면과 용접토치간의 거리를 일정하게 유지시킬 수 있도록 용접전류 센서(Welding Current Sensor)를 이용하여 토치 높이(Wire Extension)를 제어함으로써 균일한 품질의 용접비드를 얻을 수 있었다. 또한 문자마킹 자동용접장치는 본체 구동부와 제어부(Touch Screen)가 쉽게 분리되고 장착이 가능한 구조로 개발되었으며, 용접시 각 용접자세별로 용접전압, 전류 그리고 용접속도 설정이 가능하여 아래보기 자세뿐만 아니라 어떠한 자세에서도 같은 모양의 비드형상을 가지는 문자마킹용접이 가능하도록 개발하였으며, 이는 실험과 현장적용을 통해 검증하였다.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.1
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• pp.76-83
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• 2011

FCAW(Flux Cored Arc Welding) is a widely used welding method in shipbuilding. It also conducts WPS(Welding Procedure Specification) requested by the classification variations of the factors which affect the quality on the welded area such as thickness of base metal, type of welding wire and shielding gas etc. which has to be satisfied. CO2 is commonly used as a shielding gas for FCAW due to the economic point of view. The amount of shielding gas is stated when classification certify WPS. However, the shielding gas is unnecessarily used at the shipyard leaning only on the welder's experience as there are classification standards for using the shielding gas. It causes production cost to rise. Also recently, CO2 is a main contributor for global warming, and large amounts of CO2 are discharged into the atmosphere during shipbuilding processes without any filtration. Therefore it was confirmed by the security of the welded area as a result of conducting the destructive and non-destructive tests with setting up the factors and the standards by using the Taguchi method. Then the FCAW shielding gas's amounts were calculated precisely when assembling a ship. It will be applied to cost reduction and prevention of environmental pollution at the shipyard.

• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.49-56
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• 1999

Welding is a reliable process and is mainly adopted for fabricating heavy structures. Recently, transverse cracks in the weld metal is serious problem, and they affect cost, efficiency, safety and joint reliability for various welded structures. In this view of point, this study investigated the potential factors for weld metal transverse crack. The main results obtained are as follows; 1) The content of diffusible hydrogen in the commercial flux cored are welding wire was remarkable change by manufacturer. 2) The diffusible hydrogen content was thd main factor for weld metal transverse cracks. 3) Weld metal was immune to transverse cracking under the condition of low diffusible hydrogen content of high restraint condition. 4) The factors for weld metal transverse crack would be the content of diffusible hydrogen and restraint of weld joint.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.154-165
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• 1997

Abrasive wear characteristics of high Cr white cast iron-based hardfacing were investigated using the rubber wheel abrasion wear test method according with the ASTM G65-85. Mild steel was also tested for comparison with high Cr cast iron hardfacing. Wear experiments, where the applied force, wheel revolution rate and abrasive powder feed rate were selected as test valuables, were planned and analyzed by response surface method to evaluate wear statistically and quantitatively. Weight loss of high Cr cast iron hardfacing was mostly affected by the applied force and wheel revolution rate, and little by the powder feed rate. Weight loss of mild steel was greatly affected by the wheel revolution rate and powder feed rate, and slowly and steadily increased with the applied force. Abrasive wear mechanism of high Cr cast iron and mild steel was discussed in the light of the wear test results.

• Proceedings of the KWS Conference
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• v.43
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• pp.191-193
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• 2004

Inconel 625 is useful in variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{circ}C$ to over $1090^{circ}C$, in combination with good low- and high-temperature mechanical strength. Recently, this material is also used widely in offshore process piping in order to extend the maintenance term and improve the quality of anti-corrosion. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. In this study, the weldability and weldment characteristics of inconel 625 are considered in FCAW weld associated with the several shielding gases in viewpoint of welding productivity.

• Journal of Welding and Joining
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• v.10 no.4
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• pp.103-106
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• 1992

건설기계는 우리나라의 산업발전과 성장해 왔으며, 또한 발전과정에서 기여한 바도 크다. 건설 기계의 수요는 1970년대 초부터 지하철, 고속도로등 사회간접자본 개발이 활발해 짐에 따라 건 설기계에 대한 투자나 내수가 성장하기 시작하여 1980년대 후반 국가 산업규모가 확대됨에 따 라서 크게 신장하여, 1982년 내수규모가 약 2100여대이던 것이 1991년에는 16,000여대로 증가해 왔다. 이 중 대표기종인 굴삭기가 전 건설중장비의 약 76%('91년도 금액비)를 점하고 있고, 또한 건설기계는 건설작업의 성역화에 기여해 왔으며 앞으로도 이 역할은 변함없을 것이다. 최근에는 건설기계의 안전성, 공정의 자동화, 로봇화 등이 크게 요구되고 있다. 건설기계는 구조상 연강 후판(두께10-50mm)이 주류를 이루고 내마모부품이 많다. 구성부는 강판이 사용이나(총 중량의 약 30%)일부 주강과 단조품이 사용되고 있다. 경량화를 위하여 고장력강이 사용되고, 기어나 샤프트 등에는 합금강이나 탄소강이 쓰이고 있다. 생산공정은 자동화, 무인화가 추진되고 있고, 설계는 CAD/CAM화가 보편적으로 활용되고 있다. 용접은 탄산가스 아아크 용접이 대부분이고, 일부 MAG또는 플락스 충전 와이어(FLUX CORED WIRE)를 사용하고 있다. 합금강 등에는 마찰용접이나 전자 비임용접이 활용되기도 한다.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.551-556
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• 2002

Solid particle erosion wear characteristics of high Cr white iron hardfacing were investigated using the erosion wear test method according with the ASTM G76-95. Wear experiments, where the blast angle, blast distance and blast pressure were selected as test variables, were planned and analyzed by response surface method (RSM to evaluate the wear loss statistically and quantitatively. The measured wear losses well coincided with the calculated ones by the experimental equation. The wear loss of high Cr cast iron hardfacing was increased with blasting pressure, but affected in a complicated way by the blasting angle and distance. Erosion wear of high Cr cast iron hardfacing could be well predicted by RSM analysis of wear variables.