• Proceedings of the KWS Conference
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• 2002.10a
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• pp.439-449
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• 2002

This paper reviews our recent research works on the interconnection technologies in electronic packaging and assembly. At the aspect of advanced joining methods, laser-ultrasonic fluxless soldering technology was proposed. The characteristic of this technology is that the oxide film was removed through the vibration excitated by high frequency laser change in the molten solder droplet. Application researches of laser soldering technology on solder bumping of BGA packages were carried out. Furthermore, interfacial reaction between SnPb eutectic solder and Au/Ni/Cu pad during laser reflow was analyzed. At the aspect of soldered joints' reliability, the system for predicting and analyzing SMT solder joint shape and reliability(PSAR) has been designed. Optimization design method of soldered joints' structure was brought forward after the investigation of fatigue failure of RC chip devices and BGA packages under temperature cyclic conditions with FEM analysis and experimental study. At the aspect of solder alloy design, alloy design method based on quantum was proposed. The macroproperties such as melting point, wettability and strength were described by the electron parameters. In this way, a great deal of the experimental investigations was replaced, so as to realize the design and research of any kinds of solder alloys with low cost and high efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.113-117
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• 2011

The frame for automotive assembly can be deformed and remained on the residual stress due to high temperature thermal attacks when in welding. The frame deformation can be made to problems when in assembly with body and the residual stress can affect the negative effect on durability performance of the automobile. In order to analyze the frame deformation, the simplified test frame which had the similar shape (form) of the real automotive frame was fabricated. The contactless optical 3D scanner was used for the shape difference measurement of the frame between before and after the welding. The FE-model of the test frame was composed and the heat transfer and thermal stress simulation were performed. The simulated results were compared with the measured results for the reference of the frame design. The deformation shape of the frame by simulation was in good agreement with that by the experimental measurement.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.77-79
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• 2006

While RSW(Resistance Spot Welding) have been the most successful sheet metal joining process in automotive industry, there are certain qualify issues due to the control system and its application process. Recent materials and coatings make the process more complicated resulting in new challenges for quality welds. In this research, an intelligent RSW system with adaptive control algorithm is introduced to overcome typical RSW issues and its applications to automotive body assembly are presented.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.163-170
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• 2004

In order to automatically determine the sequences of block assembly operations in shipbuilding, a process planning system using case-based reasoning (CBR) is developed. A block-assembly planning problem is modeled as a constraint satisfaction problem where the precedence relations between operations are considered constraints. The process planning system generates an assembly sequence by adapting information such as solutions and constraints collected from similar cases retrieved from the case base. In order to find similar cases, the process planning system first matches the parts of the problem and the parts of each case based on their roles in the assembly, and then it matches the relations related to the parts-pairs. The part involved in more operations are considered more important. The process planning system is applied to simple examples fur verification and comparison.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.484-489
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• 2011

Nowadays, the automobile manufactures make a great efforts to reduce manufacturing cost, body weight and to develop eco-environmental parts in order to be more competitive and solve global warming. For these reasons, materials of automobile's parts are changed over from general carbon steel and stainless steel to plastic and Aluminum. And, laser welding technology is introduced to apply welding between aluminum parts. In this paper, the data of laser welding parameters is collected through lots of the experiment according to the material, welding speed and laser power to apply laser welding in Aluminum fuel filler neck assembly. After manufacturing prototype of aluminum fuel filler neck, vibration durability test, tensile strength test and salt water test are applied to verify product's satisfied function.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.34-36
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• 2000

It is difficult to realize automation of welding of lattice type in shipbuilding and assembly processing of shipbuilding and steel structures. Usually, the welding parts of lattice type are welded manually. So there are limitations in continuous and stable quality controls and in increase in productivity because the welding quality depends on worker's skill. That is, automation in welding is necessary. This paper shows shows the development results of a moblie robot for welding of lattice type. Specially. algorithms for its mobile speed and seam tracking controls are introduced.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.418-424
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• 2002

Korean Fusion Reactor(KSTAR) system consists of a vacuum vessel, in-vessel components, cryostat, thermal shield, super-conducting magnets and magnet supporting structures. These systems are in the final stage of engineering design with the involvement of industrial manufacturers. The overall configuration and the detailed dimensions of the KSTAR structure have been determined and the first stage of manufacturing is progressing now. In this study, the fabrication and assembly sequence were evaluated in viewpoint of high strengthening joints and very high accuracy. Especially for this purpose, the special cleaning process and welding process were proposed for high strengthening austenitic stainless steel which shall be used at cryogenic temperature. The draft procedure qualification data for welding process are presented with precise welding data including special narrow groove design. For the cooling line attachment on the surface of inside wall of magnet structure case, Induction brazing technology is introduced with some special jigging system and some consumables.

• Journal of Welding and Joining
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• v.27 no.2
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• pp.57-62
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• 2009

This research was carried out to improve the productivity in the subassembly process of shipbuilding through optimal work planning for the shortest work time. The work time consist of welding time, moving time of gantry, teaching time of robot and robot motion time. The shortest work time is accomplished by even distribution of work and the shortest welding sequence. Even distribution of work was done by appling the simple algorithm. The shortest work sequence was determined by using GA. The optimal work planning decreased the total work time of the subassembly process by 4.1%. The result showed the effectiveness of the suggested simple algorithm for even distribution of work and GA for the shortest welding sequence.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.53-60
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• 2014

The automatic arc welding is generally accepted as the preferred joining technique and commonly chosen for assembly of large metal structures such as in areas of automotive, aircraft and shipbuilding due to its joint strength, reliability, and low cost compared to other joint processes. Recently, several mathematical models have been developed and studied for control and monitoring welding quality, productivity, microstructure and weld properties in arc welding processes. This study indicates the prediction of process parameters for the expected welding quality with accordance to the adaptive GTA welding process. Furthermore, the mathematical models is also develop to aid the selection of an optimal welding process as the generation of process controls to predict the bead geometry as a function output parameters in the GTA welding process. The developed models through this study showed comparatively excellent predicted results, and will extend to other welding processes to integrate an optimized system for the robotic welding process.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.113-120
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• 2005

Because of the turbulent markets and the increasing demand on product quality, the application of new technology to practice is increasingly important. In case of automotive industries, they take interest in laser welding to solve these problems because laser welding has many advantages such as good accessibility, welding quality, fast welding speed and so on. To apply this technology to welding of car body, the data of laser welding are collected through lots of the experiment according to the material, geometry and layer number of welding points. Based on the experiment results and the information of product, i.e. the car side panel, the clustering of stitches for laser welding was carried out and the optimal equipments are selected through the comparison between the requirements of welding and the potential of equipments. Using these results, laser welding cell for the car side panel are configured with the concept of the digital manufacturing, which ensures maximum planning security with visualization and simulation. Finally, the optimal laser welding cell is chosen by the evaluation of alternative cells with assessment criteria.