• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.180-186
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• 2001

Underwater wet welding process was experimentally investigated by using the six types of flux coated electrodes of 3.2mm diameter and the KR-RA steel plate of 11mm thickness as base metal. Two types of electrodes were domestic covered are welding electrode(CR13, CR14) and another two types of wet welding electrodes(UW-CS-01, TN-20) and the other two types(UW-X1, UW-X2) where individually designed flux coasted electrode for experimental welding purpose.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1460-1465
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• 2012

The semi-automatic gas metal arc welding equipment was developed and the weldability of zinc coated steel pipes was evaluated in terms of strength, porosity and welding parameters including shielding gas composition. The good bead appearance and the reduction of porosity in the welds could be possibly obtained by adding $O_2$ to Ar. The strength and joint efficiency of welds made by the semi-automatic welding equipment was about 1.8 times higher compared with welds manually made. The integrity of welds was confirmed by the water pressure test as well, Finally, it is expected that the weld productivity will be enhanced even unskilled welders can produce quality welds by operating the semi-automatic welding equipment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.667-672
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• 2016

This study presents results of an experimental investigation of the laser-arc, hybrid, butt welding process of SS400 structural steel. Welding parameters including laser power, welding current and speed were varied in order to obtain one-pass, full-penetration welds without defects. The conditions that resulted in optimal beads were identified. After welding, hardness measurements and microstructure observations were carried out in order to study weld properties. The mechanical properties of both the base material and welded specimen were compared based on the results of tensile strength measurements. The yield and tensile strengths were found to be similar.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.383-389
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• 2016

In this paper, we present the hull blasting machine with vision-based weld bead recognition device for cleaning shipment exterior wall. The purpose of this study is to introduce the mechanism design of the high efficiency hull blasting machine using the vision system to recognize the weld bead. Therefore, we have developed a robot mechanism and drive controller system of the hull blasting robot. And hull blasting characteristics such as the climbing mechanism, vision system, remote controller and CAN have been discussed and compared with the experimental data. The hull blasting robots are able to remove rust or paint at anchor, so the re-docking is unnecessary. Therefore, this can save time and cost of undergoing re-docking process and build more vessels instead. The robot uses sensors to navigate safely around the hull and has a filter system to collect the fouling removed. We have completed a pilot test of the robot and demonstrated the drive control and CAN communication performance.

• Journal of Welding and Joining
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• v.17 no.4
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• pp.39-45
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• 1999

The procedure of robotic Gas metal Arc (GMA) welding in order to achieve the optimized bead geometry needs the selection of suitable process parameters such as arc current, welding voltage, welding speed. It is required the relationships between process parameters and bead geometry. The objective of this paper is to develop the algorithm that enables the determination of process parameters from the optimized bead geometry for robotic GMA welding. It depends on the inversion of empirical equations derived from multiple regression analysis of the relationships between the process parameters and the bead dimensions using the least square method. The method not only directly determines those parameters which will give the desired set of bead geometry, but also avoids the need to iterate with a succession of guesses employed Finite Element Method(FEM). These results suggest that process parameter from experimental equation for robotic GMA welding may be employed to monitor and control the bead geometry in real time.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.4
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• pp.417-423
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• 2009

This paper is concerned with the fatigue behaviour of welded joints by the notch stress approach. The actual welded shape is complex and 3-dimensional that may influence greatly the fatigue strength. The purpose of the paper is to present a way of modelling the actual weld bead shape by using a 3-D Laser scanner for experimental models of steel plates with longitudinal fillet welds, and applying its results to a proper notch stress method for the fatigue strength. The present approach to assess the fatigue strength is quite promising with application to a variety of welded joints and effects of weld profiling to fatigue strength.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.6
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• pp.25-31
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• 2014

Gas metal arc welding (GMAW) is currently the most widely used arc welding processes in the industry because of its high metal deposition rate, flexibility and low cost. It is attractive for high-productivity manufacturing applications and is well suited to automatic or robotic welding. Welding voltage and current have a significant impact on the weld bead. However, welding voltage and current are changed variously according to welding condition and user environment, and prediction is impossible. To determine the welding conditions, the welding current and voltage are applied to the appropriate data analysis techniques. In this paper, we used the moving average filter to the welding voltage and current data, and normal and abnormal welding waves were distinguished.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.230-237
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• 2015

To improve productivity and improve the welding process, we have studied the automated system of the weld by applying a tandem welding. Then, the speed of the welding process is improved, production of industries is increasing. Productivity of the industrial sector has increased the application of tandem welding for automated system of welding. But quality assurance for the product take place welding defects in the welding process because the speed of the process is increased. Definitive research solutions an dit's actuality, however, there is insufficient. Accordingly, it is a situation that the performance of the weld to ensure quality of the weld is required urgently after the welding process. Comparing and analyzing the results of passing each experiment of the two-electrode welding and the welding electrode1, a study attempted to quality assurance of the welded joint portion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.901-906
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• 2016

The purpose of this study is to improve productivity by implementing one-pass full penetration welding using laser-arc hybrid welding for AH36. On increasing the thickness of the plate, a higher power of laser and arc was required to obtain full penetration. However, increasing the power of heat source caused undercut defects at both ends of the bead. This undercut was prevented by controlling the parameters of welding voltage and pulse correction. Hardness measurement and tensile test were conducted to apprehend the mechanical properties of weld. Also, by carrying out the microstructure observation for laser and arc regions, microstructural properties were understood.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.7-7
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• 2009

TIG 용접에서는 후판 용접의 경우 용입의 한계 때문에 깊고 넓은 그루브 가공을 하여 다층 용접을 한다. 이 때, 그루브를 채우는 용착금속에 의한 응고 수축과 과대한 입열로 인한 변형이 문제시 되고 있다. 변형을 줄이기 위해서는 용착금속의 양과 입열량을 줄여야 한다. 이러한 문제를 해결하기 위해 그루브의 루트패이스를 두껍게 하고 그루브각을 줄여서 용착량을 줄인다. 이때, 좁은 그루브에서 두꺼운 루트패이스를 완전 용입할 수 있는 용접 프로세스가 필요하다. 비드가 좁고 깊은 용입 특성을 가지는 Plasma welding(PAW) 경우에는 좁은 그루브 속에 토치가 접근하기 어려워 적용하기 어렵다. 따라서 접근성이 용이한 TIG 용접에서 높은 용입형상비를 가지는 용접공정 개발이 필요하다. 선행연구로 높은 용입 형상비를 가지는 Active flux Tungsten Inert Gas(ATIG) 용접이 연구되었다. ATIG의 용입 증가 메커니즘으로는 Marangoni effect, 음이온들로 인한 아크 수축 효과, 절연 플럭스에 의한 아크 수축효과 등으로 알려져 있다. 또한 선행연구에서 ATIG에서 Ar가스에 He 또는 $H_2$ 가스를 첨가하면 용입이 더욱 증가하는 것을 확인하였다. 본 연구에서는 A-TIG에 He 가스를 적용하고 아크길이 0.5mm, 1.0mm, 2.0mm와 전극 선단각 30도, 60도, 90도에 따른 용입 형상비와 변형량을 검토하기 위해 실험을 하였다. 실험 결과는 아크길이가 감소할수록 전극 선단각이 증가할수록 용입 형상비는 증가하였고, 변형량은 감소하였다.