• Proceedings of the KWS Conference
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• v.43
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• pp.251-253
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• 2004

• Journal of the KSME
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• v.34 no.2
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• pp.78-87
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• 1994

이 글에서는 아직까지 우리나라의 기술수준이 낙후되어 있고 앞으로 개발의 여지가 많은 건설중 장비, 조선산업 등에서 많이 사용되는 중후판을 대상으로 하는 보호가스 아크용접(GMAW ; Gas Metal Arc Welding)자동화에 관하여 서술하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.633-634
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• 2006

• Proceedings of the KWS Conference
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• 1996.10a
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• pp.145-147
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• 1996

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.131-138
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• 2010

Recently, extruded aluminium-alloy panels have been used in the car bodies in order to meet the needs for the speed-up and light-weight of the railway vehicles. Most of the car bodies were jointed by arc weldings, like GMAW (GasMetal Arc Welding) and GTAW (Gas Tungsten Arc Welding), but these weldings became fairly worse the mechanical properties of the junction than the base metal. Nowadays, FSW (Friction Stir Welding), which is superior to the arc weldings, has been applied in the railway vehicles. In this study, the mechanical properties of the joints in both FSW and GMAW for A6005 extruded aluminium-alloy sheets have discussed. In addition, the relationships between the welding conditions and the mechanical properties for the joint of FSW have analyzed through the sensitivity analysis. It can be concluded that the mechanical properties for the joint of FSW are better than those of GMAW and the welding speed is the most sensible welding condition in the process of FSW.

• Journal of Welding and Joining
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• v.11 no.1
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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 the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.132-139
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• 2002

In GMAW(Gas Metal Arc Welding) processes, bead geometry (penetration, bead width and height) is a criterion to estimate welding quality. Bead geometry is affected by welding current, arc voltage and travel speed, shielding gas, CTWD (contact-tip to workpiece distance) and so on. In this paper, welding process variables were selected as welding current, arc voltage and travel speed. And bead geometry was reasoned from the chosen welding process variables using neuro-fuzzy algorithm. Neural networks was applied to design FL(fuzzy logic). The parameters of input membership functions and those of consequence functions in FL were tuned through the method of learning by backpropagation algorithm. Bead geometry could be reasoned from welding current, arc voltage, travel speed on FL using the results learned by neural networks. On the developed inference system of bead geometry using neuro-furzy algorithm, the inference error percent of bead width was within $\pm$4%, that of bead height was within $\pm$3%, and that of penetration was within $\pm$8%. Neural networks came into effect to find the parameters of input membership functions and those of consequence in FL. Therefore the inference system of welding quality expects to be developed through proposed algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.257-258
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• 2012

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.48-48
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• 2009

Conventionally in pulsed gas metal arc welding (GMAW-P), drop transfer is analyzed with simplest square pulse waveform. While the pulse current is described by four parameters (peak current magnitude and time plus base current magnitude and time), it deviates the real pulse shape. Real pulse can be better idealized by the trapezoidal pulse waveform described by two additional parameters, i.e., current rise and fall rate (dI/dt). Power source response rate is described by these parameters. In this work, the effect of these parameters on drop transfer is predicted by the force displacement model (FDM). While peak current has significant effects on drop detachment, drop transfer is also influenced by the current rise rate. Predictions indicate that the current rise rate can have considerable effects on the size of the detached drop if other pulse parameters are kept constant. FDM is applied to determine peak time for one drop one pulse condition (ODOP) when rests of the pulse parameters are given. The predicted range of ODOP shows good agreement with experimental data.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.16-27
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• 1994

1970년대 2번에 걸친 석유 파동 이후 재료의 경량화는 자동차, 우주항공분야에서 중요한 문제로 대두되었다. 알루미늄합금은 높은 강도/밀도비, 내식성, 인성 및 저온 특성을 보유하고 있어 일반 가정용품에서 자동차, 우주항공, 선박같은 수송장비까지 여러분야에 사용되고 있으며, 그 사용량과 적용분야는 해가 갈수록 증가하고 있다. 알루미늄합금의 용접특성과 용접 시공기술에 대한 연구결과는 상당히 많이 발표되어 있으나, 실제 현장용접시에는 기공, 불완전 용입 등의 예상치 못한 용접불양이 발생한다. 알루미늄합금의 용접 방법으로는 GTAW, GMAW 등의 보호가스 용접이 주로 사용되고 있다. 본 고에서는 알루미늄합금의 GMAW용접 특성과 용접시 용접 결함에 대하여 간단히 기술하고자 한다.