• Transactions of the Korean Society of Mechanical Engineers
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• 제13권6호
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• pp.1156-1169
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• 1989

본 연구에서는 용접도중 발생할 수 있는 용접질 저항요인을 전극분리현상을 측정하여 파악하고 용접 열입력에 해당하는 용접전류를 학습제어방식(self-learning control)에 의하여 컴퓨터와 주변기기(interface)를 통해 조절함으로서 요구되는 균일한 용접질이 항상 보장되도록 하였다. 여기서 학습제어방식을 태택한 이유는 제어하고자 하는 대상의 동적 모델(dynamic model)이 없어도 제어기 이득의 선정이 비교적 자유롭고 용접 제어장치가 자체적으로 감지(monitoring)한 신호로 판단하여 제어동작을 취함으로서 용접시 축적되는 정보(data)가 용접기에 일종의 지능을 부여할 수 있어서 진보된 개념의 용접제어장치 개발의 가능성을 검토해 보기 위함이다.

• Proceedings of the KWS Conference
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.175-177
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• 2006

• Proceedings of the KWS Conference
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.149-151
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• 2003

The development of lightweight car bodies is the most prominent issue in the automotive industry today, in preparation of environmental regulations such as reduction of CO$_2$ emissions. Also, with the recent implementation of mandatory off-set collision test, many studies have been carried out to enhance the safety of automobiles. Recently, TRIP(Transformation Induced Plasticity) steel has developed as a prominent alternative due to its high strength and superior elongation. In this study, TRIP steel weldability is evaluated with lobe curve, continuous spot welds, shunt effect, and weld of edge position.

• Transactions of the Korean Society of Mechanical Engineers
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• 제17권2호
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• pp.393-406
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• 1993

In resistance spot welding process, size of molten nuggest have been utilized to assess the integrity of the weld quality. However real-time monitoring of the nugget size is an extremely difficult problem. This paper describes the design of an artificial neural networks(ANN) estimator to predict the nugget size for on-line use of weld quality monitoring. The main task of the ANN estimator is to realize the mapping characteristics from the sampled dynamic resistance signal to the actual negget size through training. The structure of the ANN estimator including the number of hidden layers and nodes in a layer is determined by an estimation error analysis. A series of welding experiments are performed to assess the performance of the ANN estimator. The results are quite promissing in that real-time estimation of the invisible nugget size can be achieved by analyzing the dynamic resistance signal without any conventional destructive testing of welds.

• Proceedings of the KWS Conference
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.311-313
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• 2005

• Journal of the Korean Society of Mechanical Technology
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• 제13권4호
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• pp.143-148
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• 2011

This study analyzes the resistance spot weldability of DP60 steels. To analyze the resistance spot weldability of DP60 steels, tensile strength test and macro-section test were conducted for the resistance spot welds. Acceptable welding conditions were determined as a function of the resistance spot welding process parameters such as electrode force, welding time, and welding current. The lower limit of the welding lobe was the minimum shear tension strength for 590MPa-grade steel while the upper limit was determined whether or not expulsion was detected.

• Journal of Welding and Joining
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• 제30권1호
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• pp.19-26
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• 2012

• Journal of Welding and Joining
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• 제29권6호
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• pp.26-32
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• 2011

• Journal of Welding and Joining
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• 제17권5호
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• pp.77-82
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• 1999

Resistance spot welding process is completed in very short time and there are many factors affecting on the generation of heat. It is difficult to control these experimental factors and monitor distribution of the temperature and stresses in the experimental analysis case. and too much time and expense are required for the experimental trials to fine proper welding condition. So numerical analyses have been attempted steadily, but most numerical analyses on the resistance spot welding are mainly focused on thermal behavior. Therefore, in this paper, the numerical analysis of mechanical behavior as well as heat conduction is carried out for the spot welding process. For this numerical analysis, axial symmetric computer program for the spot welding analysis by F.E.M. has been developed considering heat conduction and thermal elastic-plastic theory. Material properties depending on temperature such as density, heat conductivity, heat expansion coefficient, specific heat, yield stress, elastic modulus, and specific resistance are considered. Using the results of temperature distribution obtained from heat conduction analysis, the thermal elastic-plastic analysis is carried out to clarify mechanical behavior of spot welded specimen. In order to evaluate the effect of residual stresses, numerical analyses are carried out under tension-shear load in two cases respectively; one with residual stress, the other without residual stresses.

• Proceedings of the KWS Conference
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• 대한용접접합학회 2008년도 춘계학술발표대회 개요집
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• pp.24-24
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• 2008