• Journal of Welding and Joining
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• 제14권3호
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• pp.12-19
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• 1996

Spot 용접의 역사는 1877년에 E. Thomson이 발명한 것이지만 1886년 처음으로 저항 용접기의 특허를 취득할 때까지는 거의 실용화 되지 못하였다. 그 후 Thomson의 전기 용접기 회사가 저항 용접의 특허를 거의 독점한 관계로 커다란 발전없이 spot 용접에 관한 특허 분쟁이 해소된 1920년 이후 보급되기 시작하여 1935년경 부터 증가 하였다. 초기에는 주로 맞대기 용접에 이용되고 전선의 접합이나 크게는 rail의 용접 에까지 이르렀다. 금세기에 들어와서부터 spot 용접이나 seam 용접이 실용화되고 관련 용접 장치도 개발되었다. Spot 용접은 자동차 공업과 더불어 크게 발전하였으며 오늘 날에는 spot 용접 생산의 약 2/3를 자동차 공업이 점유하고 있다. Spot 용접은 고온 압접의 일종으로 각종 압접 방법중에서 가장 많이 사용되고 있는 것이다. 접합하고저 하는 부분에 직접 고전류를 통하고 그 전류에 의한 저항 발열로 용접부의 온도를 상승 시켜 용접하는 것으로서 극히 짧은 시간에 용접이 가능하고 고속, 고능률이므로 특히 다량 생산에 적합하다.

• Journal of Welding and Joining
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• 제6권3호
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• pp.21-26
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• 1988

The behavior of angular distortion in butt joint wleding of thin plate structure is investigated with an experimental model and partially with a computational model. The experimental model studying the effects of specimene size and degree of restraint on the angular distorion offers a good method for analyzing the behavior of the distrotion. In addition, the distrotion during welding was demonstrated by both experimental measurement and numericla prediciton. The facts evealed in this study are as follows : 1) distrotion angles were changed with variations of specimene wldth. 2) With the restraint, angular distrotion was reduced to 20% to that of free joint. 3) After the restraint being removed, the effect of restraint was also remained. 4) Same heat input per unit thickness caused same amount of distortion. 5) The mode of angular distortion was expected to be changed with expected to be changed with time, i.e. convex movement during heating and concave one during cooling.

• Journal of Welding and Joining
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• 제21권1호
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• pp.80-86
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• 2003

This study develops a system for effective prediction of residual stresses by the backpropagation algorithm using the neural network. To achieve this goal, a series of experiments were carried out to and measured the residual stresses using the sectional method. With the experimental results, the optional control algorithms using a neural network could be developed in order to reduce the effect of the external disturbances during GMA welding processes. Then the results obtained from this study were compared between the measured and calculated results, weld guality might be controlled by the neural network based on backpropagation algorithm.. This system can not only help to understand the interaction between the process parameters and residual stress, but also improve the quantity control for welded structures.

• Journal of Welding and Joining
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• 제18권2호
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• pp.204-204
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• 2000

There are many weld defects such as surface crack, lack of fusion, and incomplete penetration(IP) in the butt joint weld of the existing steel bridges. The crack-like defects may significantly reduce the life of the structure. This paper presents the procedure and the results of the fatigue life assessment of the butt joints with weld defects in the existing steel girder bridge. The butt joint welds with incomplete penetration were instrumented with strain gages to determine the stress histogram under normal traffic. Based on the measured stress histogram the crack propagation analysis were performed for the fatigue life assessment. By using the suggested procedure and methodology, one can decide the time of periodic inspection and the necessity of repair of the butt joint welds with serious weld defects in the existing steel bridge. (Received October 1, 1999)

• Journal of Welding and Joining
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• 제18권2호
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• pp.77-85
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• 2000

There are many weld defects such as surface crack, lack of fusion, and incomplete penetration (IP) in the butt joint weld of existing steel bridges. The crack-like defects may significantly reduce the fatigue life of the structure. This paper presents the procedure and the results of the fatigue life assessment of the butt joints with weld defects in the existing steel girder bridge. The butt joint welds with incomplete penetration were instrumented with strain gages to determine the stress histogram under normal traffic. Based on the measured stress histogram the crack propagation analysis were performed for the fatigue life assessment. By using the suggested procedure and methodology, one can decide the time of periodic inspection and the necessity of repair of the butt joint welds with serious weld defects in the existing steel bridge.

• Journal of Welding and Joining
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• 제8권1호
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• pp.12-22
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• 1990

우리나라와 선진 각국에서는 구체적인 부분까지 상당량을 규격(standard)으로 제정해 놓고 있다. 규격의 내용을 전반적으로 언급하기는 어렵기 때문에, 여기서는 범위를 좁혀 한 분야의 계통을 선택하여 설명하고자 한다. 즉, 강재의 맞대기 용접부에대하여, 사각탐촉자에 의한 탐상법을 예시적으로 선택하고 KS B 0896 규격을 중심으로 설명하는 내용이다. 이와 관련한 내용들은, 탐상장치의 성능시험, 거리진폭 특성곡선, 결함 및 탐상에 관한 사전준지, 결함의 탐상방법 등이며, 참고로 한국 일본 미국의 초음파 탐상시험에 관련된 규격명을 열거한다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.257-259
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• 2007

For this study, SM45C steel rods using generally for power transmission shafts and machine components was selected and welded by Butt-GMAW method. and then it was studied about estimation of fatigue strength and the region of infinite life. From this result, it is demanded that the stress for safety design of machine components using SM45C butt-welded steel rods must be selected in the region of the lowest infinite life of heat affected zone.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 추계학술발표대회 개요집
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• pp.3-6
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• 2001

• 한국강구조학회 논문집
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• 제13권5호
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• pp.547-556
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• 2001

본 연구에서는 실험을 통해 용접이음부의 형상 및 구속도의 크기 등을 변화시켜 측정한 용접 각변형량과 FEM해석을 이용한 해석결과로부터 구속계수를 유도하고 이를 고려한 등가하중을 결정하는 새로운 방법을 제시하였다. 새롭게 제시한 등가하중 결정 방법에 의한 수치해석결과는 실험결과와 잘 일치하여 그 타당성이 검증되었으며, 크기와 형상에 관계없이 대형구조물의 용접변형량을 예측하는데도 확대 적용할 수 있다. 한편 용접이음부 형상에 따른 구속에 대한 영향을 보면 맞대기용접의 경우 구속계수를 고려하지 않으면 실제 변형량보다 변형이 크게 발생하여 구속에 대한 영향을 크게 받으며 필렛용접의 경우 구속계수의 고려 유 무에 관계없이 거의 같은 변형량이 발생함으로써 구속에 대한 영향이 작음을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1560-1565
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• 2005

Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameters such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar plates, etc. The following conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.