• Journal of Welding and Joining
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• 제15권3호
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• pp.36-46
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• 1997

Dynamics of molten drop detachment in the Gas Metal Arc (GMA) welding is investigated using the Volume of Fluid(VOF) method. The electromagnetic effects are included in the formulation of the VOF method which has been widely used to analyze the dynamics of the fluid having a free surface. The molten drop geometry, pressure and velocity profiles within the drop are calculated numerically in the cases of globular and spray transfer modes. It appears that the velocity and current distribution affect metal detachment. It is found that the taper is formed and maintained during the spray transfer by the electromagnetic force. Predicted results show reasonably good agreement with the available experimental data which validates the application of the VOF method to metal transfer analysis.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.111-113
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• 2005

• Journal of Welding and Joining
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• 제17권1호
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• pp.55-61
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• 1999

The effect of S content in welding wires on the arc stability was investigated, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing S content, average arcing time and average short circuit time were decreased. Therefore, droplet transfer frequency was increased, due to the reduction of arcing time and peak current at the moment of arc-reiginition was decreased, due to the decrease of short circuit time. In the region of spray transfer, the fluctuation degree of arc current and arc voltage became more stable, with increasing S content.

• Journal of Welding and Joining
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• 제17권3호
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• pp.36-43
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• 1999

The effect of Si content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80% Ar-20% $CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with Si content of wire. With increasing Si content, the spattering ratio and the ratio of large size spatter $(d\geq1.0mm)$ were increased. The increase of Si content in molten metal made surface tension increase due to reduction of oxygen content, which resulted from deoxidizing action of silicon. The increase of surface tension resulted in unstable transfer phenomena and arc instability in both short circuit and spray region. With changing Si content of wire, spattering characteristics and droplet transfer phenomena was directly influenced by the variation of surface tension, compared with the effect of arc stability.

• Journal of Welding and Joining
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• 제16권6호
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• pp.52-58
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• 1998

The effect of Si content in welding wires on th arc stability was investigate, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing Si content, average arcing time and average short circuit time were increased. Therefore, droplet transfer frequency was decreased, due to the increase of arcing time and peak current at the moment of arc-reiginition was increased, due to the increase of short circuit time. In the region of spray transfer, the fluctuations of arc current and arc voltage was the most stable in wire with Si content of about 00.60 wt.%.

• 보건의료생명과학 논문지
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• 제9권1호
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• pp.141-146
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• 2021

호신용 스프레이의 자극성 액체에 포함된 capsaicin, dihydrocapsaicin 및 nonivamide의 함량을 기체 크로마토그래피로 정량하는 방법에 대해 연구하였다. Capsaicin과 거의 동등한 수준의 매운맛을 내는 nonivamide는 천연물 내에도 극히 소량 존재하므로 합성된 nonvamide를 합성 캡사이신(Synthetic capsaicinoid) 또는 PAVA(Pelargonic Acid Vanillyl Amide)라고 부르며 식품 향미 재료나 폭동진압용 무능화 작용제로 이용되어왔다. 호신용품이 난립하는 요즘 각종 불법 호신용 스프레이의 품질관리가 제대로 이행되지 않는 사례가 종종 발견되고 있다. 따라서 기체크로마토그래피로 합성 캡사이신이 포함된 제품이 천연 유래인 것처럼 도용되거나 허용농도를 준수하는 지를 판별할 수 있는 간단한 분석방법을 개발하고자 하였다. 마지막으로 분석방법이 확립되면 시판되는 호신용 스프레이 내에 존재하는 자극성 액체의 성분과 함량 조사에 응용하여 보았다.

• Journal of Welding and Joining
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• 제13권1호
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• pp.127-137
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• 1995

The possibility of new GMAW process using economic shielding gases including CO$_{2}$ gas was investigated on the effect of shielding gas on weldabilty. In the optimum welding condition using 600A power source, FCAW process showed low depositions rate, 114 g/min at 300A, but new GMAW using other mixed shielding gases exhibited high deposition rate, 208-224 g/min at 450A. TIME gas, Ar+CO$_{2}$ gas and Ar+CO$_{2}$+O$_{2}$ gas as a shielding gas were able to be used to the very high welding current(450A), moreover TIME gas and Ar+CO$_{2}$ gas showed the highest arc stability among shielding gases studied in this experiments. The weld penetration was performed by axial spray transfer mode of weld droplet. On the basis of workability, weldability and economic point of view, Ar mixture (80%Ar+20%CO$_{2}$) gas was recommended as a shielding gas for the development and application of new GMAW process. This shielding gas showed the low spatter, good weld quality, stable arc and low cost at the region of high welding current.