• Journal of Welding and Joining
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• 제11권1호
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• pp.73-79
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• 1993

The phenomenon of metal transfer has been investigated for different transfer modes using a digital high speed motion analyzer and an arc shadow-graphing system based on a laser source and related optical system. It was observed that the pinch instability phenomenon did not occur for the globular transfer mode, since the liquid globule was then spherical rateher than a cylindrical liquid bar. On increasing the ratio of carbon dioxide to argon, the transition current from globular to spray transfer generally increased, but it is interesting that the transition was observed to occur at the lowest current in a 5% CO$_{2}$-95% argon gas mixture. For pure carbon dioxide and helium shielding gases, the drop frequency increased slowly with increasing current. At high currents or an argon based shielding gas, the length of liquid bar decreased as the carbon dioxide content increased. The acceleration of a droplet within the arc was determined using the gas drag force theory and was found to be greater than the experimental results.

• Journal of Welding and Joining
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• 제19권2호
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• pp.200-207
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• 2001

Three-diemnsional bead profile was measured using the biprism stereo vision sensor in GMAW, which consists of an optical filter, biprism and CCD camera. Since single CCD camera is used, this system has various advantages over the conventional stereo vision system using two cameras such as finding the corresponding points along the horizontal scanline. In this wort, the biprism stereo vision sensor was designed for the GMAW, and the linear calibration method was proposed to determine the prism and camera parameters. Image processing techniques were employed to find the corresponding point along the pool boundary. The ism-intensity contour corresponding to the pool boundary was found in the pixel order and the filter-based matching algorithm was used to refine the corresponding points in the subpixel order. Predicted bead dimensions were in broad agreements with the measured results under the conditions of spray mode and humping bead.

• Journal of Welding and Joining
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• 제2권1호
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• pp.58-65
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• 1984

NGW(Narrow Gap Welding)는 개선폭이 약 9mm로서 연강 및 저탄소강을 용접할 경우 두께가 300mm까지 1층으로 용접이 가능하다. 따라서 두께가 두꺼운 발전설비, 원자력 설비, 화학 설비 등의 압력용기의 용접에 적합한 용접법이다. 그러나 실제적인 NGW의 적용은 제작자의 친근 감의 결여, 기술 부족 및 복잡성 등의 이유로 아직도 비교적 널리 활용되지 않고 있다. 새로운 type의 GMAW-NG process가 발전되어 오고 잇다. 위와 같은 장점과 단점을 비교해 볼 때 낮은 operating 경비, 높은 joint filling rate, 변형과 잔류 응력의 감소 등으로 세계적인 용접 전 문가들의 계속적인 관심도가 높아지고 사용도도 증가하고 있다. narrow gap welding의 장단점을 요약하면 아래와 같다. 장 점 1) 생산성이 높다. 2) 고품질을 얻을 수 있다. 3) 잔류 응력과 변형을 적게 한다. 4) 전자세 용접이 가능하다. 단 점 1) 용접기의 가격이 비싸다. 2) 용접 품질에 큰 영향을 주는 아아크가 작업 조건에 따라 민감하게 변한다. 3) repair procedure는 다른 용접 방법을 요구한다. 4) 과도한 복잡성 때문에 장비의 신뢰성이 낮다.

• Journal of Welding and Joining
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• 제28권4호
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• pp.55-60
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• 2010

The purpose of this paper is to propose a mathematical model of welding current for the P-GMAW by modifying the well known GMAW model. Welding power circuit is simply modeled as a RL electric circuit and solved as an ODE equation. The welding current depends on the joint shape, molten pool and welding parameters. To compare the molten pool effect to the welding current, CFD numerical simulation technique was adopted. Welding experiment is also conducted with the same welding parameters as used in numerical simulations to verify the proposed welding current model. The current model which is considered molten pool shape, is more fit to experiment result.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.1-6
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• 2001

A weld quality assessment method is proposed in this work, which can be applied to the short-circuit mode in GMAW. Information about the welding signal trajectory, distribution of the signal duration at each sub-regions and short-circuit frequency is used to evaluate the weld quality. The weighted penalty, which is determined experimentally, is imposed for each abnormal signal. Performance of the proposed method is compared with the Simpson's method under the conditions of shielding gas reduction, workpiece surface contamination and joint gap in the butt and fillet welds. Although the proposed method predicts the weld quality with reasonable accuracy, further modification and extension to other metal transfer modes are needed as a further study.

• 한국강구조학회 논문집
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• 제25권4호
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• pp.431-440
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• 2013

본 연구에서는 HSA800 후판 강재에 적합한 용접재를 선정하고자 표준인장실험을 수행하였다. 본 연구 수행 당시 HSA800 강재에 적용가능한 용접재로 GMAW 용접재(외국산)와 FCAW 용접재(국내산) 두 가지가 추천되어 이들을 사용하였다. 맞댐용접상세와 루트간격을 주요 실험변수로하여 표준인장실험을 통해 용접부의 성능을 평가하였다. 강도에 대한 설계요구조건은 두 용접재 모두 만족하였으나 연성능력 측면에서 GMAW 용접재 보다는 FCAW 용접재가 일관되고 우수한 거동을 보임이 실험적으로 확인되었다. 특히 GMAW 용접재는 용접효율과 작업성의 문제로 현장에서의 상향용접이 어려운 것으로 파악되었다. 같은 완전용입용접이라도 Single bevel보다는 V-groove가 안정적인 구조거동을 보이는 것으로 나타났다. 또한 현행 용접기준의 표준루트 간격을 벗어날 경우 용착의 어려움으로 비정상 파단면이 형성되고 접합성능도 저하됨이 확인되었다. 부분용입용접 접합부의 실험결과에 의할 때 현행 AISC 기준의 부분용입용접부 강도규정은 매우 보수적임이 확인되었다.

• Journal of Welding and Joining
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• 제31권1호
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• pp.11-20
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• 2013

Recent developing tendency of overlay welding on welding methods are studied by searching of NDSL, ScienceDirect and KIPRIS. PTA, Laser cladding, SMAW, GTAW, GMAW, SAW and ESW are selected as welding methods. Development and improvement of various new overlay welding processes and technology are introduced, especially PTA and Laser cladding in abroad overlay welding technology are activated substantially.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.317-320
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• 2005

In this paper, dynamic behaviour of short circuit occurring in Pulse Gas Metal Arc Welding (GMAW-P) is investigated Welding experiments with different values of pulsing parameters, high speed camera pictures and welding signals such as current and voltage were acquired to identify short circuit conditions in GMAW-P.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.217-219
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• 2005

In the conventional GMAW of 9% Ni steel, Inconel wire has been employed. The major problem of the Inconel GMAW is that arc stability and fluidity of weld pool is poor. Lack of fusion and convex weld bead is liable to occur in case of 9% Ni steel because of low melting point of Inconel wire. In this study the effect of shielding gases on the Inconel 625 GMA weldability was investigated.

• Journal of Welding and Joining
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• 제30권4호
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• pp.14-18
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• 2012