• Proceedings of the KWS Conference
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• 2007.11a
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• pp.150-152
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• 2007

It has been known that the underfilling technique is effective in reducing thermal and environmental stress concentration at solder joint in FC asscemblies. In this paper, the effect of thermomechanical properties of underfill such as coefficient of thermal expansion(CTE) and Young's modulus on reliability of FC assembly under thermal cycling was investigated. For parametric study for optimal design of underfill, finite element analyses(FEA) were performed for seven different CTEs and five different Young's modulus. The results show that the concentrated maximum stress decreases as Young's modulus of underfill increases and the CTE of underfill decreases.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.483-486
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• 2001

This Paper the state-of-the art indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter whice can operate in the frequency range from 20kHz to 50kHz. A specially-designed induction heater composed of laminated stainless assembly with many tiny holes and interconnected spot welding points between stainless plates is inserted into the ceramic type vessel with external working coil connected to the inverter and tubelence fluid through this induction heater in moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.519-529
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• 1998

In automotive industries the stamping of laser-welded blank gives many merits which bring about dimensional accuracy, strong body assembly and high productivity. However the welding of blanks with different thickness or/and different strength materials introduces many challenging formability problems for process development and tool design. in this paper the deformation characteristics for deep drawing process of laser-welded blank with different thickness sheets are investigated by experiment as well as by FEM simulation. The blank holding force ratio to avoid the movement of weld line was suggested and compared with the experimental result for cylindrical and rectangular cup drawing process. The optimal location of weld line in laser-welded blank with different thickness sheets is calculated to compensate for the movement of weld line on deep drawing process. In addition the effect of location of weld line on formability is clarified using FEM simulation.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.100-107
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• 1998

This paper presents the development of estimation model and control method based on the new robot vision. This proposed control method is accomplished using the sequential estimation scheme that permits placement of the rigid body in each of the two-dimensional image planes of monitoring cameras. Estimation model with six parameters is developed based on the model that generalizes known 4-axis scara robot kinematics to accommodate unknown relative camera position and orientation, etc. Based on the estimated parameters, depending on each camera the joint angle of robot is estimated by the iteration method. The method is experimentally tested in two ways, the estimation model test and a three-dimensional rigid body placement task. Three results show that control scheme used is precise and robust. This feature can open the door to a range of application of multi-axis robot such as assembly and welding.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.784-798
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• 2020

This paper presents the results of research on transverse shrinkage of welded butt joints conducted according to the principles of experimental design and under production conditions for two main welding techniques used in shipbuilding (FCAW and SAW). Analysis took into account the technological and structural parameters influencing the assembly suitability of a large steel structure. The presented method of evaluation makes it possible to apply approximation formulae to predict transverse shrinkage in real sections of a ship hull. The determined predictive formulae were verified to actual transverse shrinkage measurements during prefabrication of hull sections at a shipyard as well as the equations referring to the analyzed form of deformation available in the literature.

• Journal of Ocean Engineering and Technology
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• v.31 no.6
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• pp.425-430
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• 2017

In order to reduce the cost of corrections and time needed for the block assembly process, the reverse setting method is applied for a back-heated block to neutralize deck deformation. The proper reverse setting shape for a back-heated block to correct deformation improved the deck flatness, but an excessive amount of reverse setting could inversely affect the flatness of the block. A prediction method was developed for the proper reverse setting shape using a back-heated block, considering the complex geometry of blocks, thickness of the deck plate, and thermal loading conditions such as welding and back-heating. The prediction method was developed by combining the re-meshing technique and inherent strain-based deformation analysis using the finite element method. Because the flatness deviation was decreased until the lower critical point and thereafter it tended to increase again, the optimum value for which the flatness was the best case was selected by repeatedly calculating the predefined reverse setting values. Based on this analysis and the study of the back-heating deformation of large assembly blocks, including the reverse setting shape, the mechanism for selecting the optimum reverse setting value was identified. The developed method was applied to the actual blocks of a ship, and it was confirmed that the flatness of the block was improved. It is concluded that the developed prediction method can be used to predict the optimum reverse setting shape value of a ship's block, which will reduce the cost of corrections in the construction stage.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.720-725
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• 2002

In recent years, techniques for micro-assembly with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Adhesion phenomenon is more significant for smaller objects, becanse adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. It is also known that adhesional force between micro-objects exposed to Electron Beam irradiation of SEM increases with the elapsed time. Therefore, mechanical manipulation techniques using a needle-shaped tool by adhesional force are often adopted in basic researches where micro-objects are studied. These techniques, however, have not yet achieved the desired repeatability because many of these could not have been supported theoretically. Some techniques even need the process of trial-and-error. Thus, in this paper, mechanical and adhesional micro-manipulation are analyzed theoretically by introducing new physical factors, such as adhesional force and rolling-resistance, into the kinematic system consisting of a sphere, a needle-shaped tool, and a substrate. Through this analysis, they are revealed that how the micro-sphere behavior depends on the given conditions, and that it is possible to cause the fracture of the desired contact interfaces selectively by controlling the force direction in which the tool-tip loads to the sphere. Based on the acquired knowledge, a mode diagram, which indicates the micro-sphere behavior for the given conditions, is designed. By refening to this mode diagram, the practical technique of the pick and place manipulation of a micro-sphere under an SEM by the selective interface fracture is proposed.

• Journal of Fashion Business
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• v.16 no.6
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• pp.21-35
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• 2012

In consideration of the injuries and deaths occurring at manufacturing sites due to the use of inappropriate work clothes or safety devices, this study aims to categorize manufacturing work processes to develop functional work clothes for heavy industries including the automobile, machine and shipbuilding industries in South Korea. Defining the features of the work environments and work postures of these industries provided for a categorization of the work processes which would enable the development of suitable work clothes for each work process' category. The results of the study based on a questionnaire survey are as follows: Work process category 1, including steel panel pressing and auto body assembly, final inspection (in automobile) and inspection (in machine), requires work clothes with upper body and arm mobility and performance to protect from the toxic fume factor. Work process category 2, consisting of welding (in automobile), cutting-and-forming (in machine) and attachment-and-construction (in shipbuilding), requires clothing elasticity, durability and heat and fire resistance. Work process category 3 comprising welding and grinding in the machine and shipbuilding industries, requires work clothes' tear resistance and elasticity, particularly for lateral bending mobility, and work clothes' sleeves' and pants' hemlines with sealed designs to defend against iron filing penetration, as well as incombustible and heat-resistant material performance. Finally, work process category 4, including painting in machine and shipbuilding, requires work clothes with waterproofing, air permeability, thermal performance, elasticity, durability and abrasion resistance.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.495-505
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• 2008

With the high proportion of zinc coated steels in body-in-white assembly, newly developed surface roughness textured galvannealed steel sheets have been introduced. In this study, zinc coated and surface roughness textured steel sheets were welded by resistance spot welding to investigate its weldability including electrode wear test. Based on the results of tensile-shear test, nugget diameter changes, and electrode tip growth test, it was clear that both surface roughness textured steels (GA-T and GA-E) showed good weldability. Also, there was no large difference in weldability and electrode wear behavior between GA-T and GA-E steels which have different surface roughness morphology. An analysis of electrode degradation showed Fe and Zn penetration through the electrode tip surface at 2400 welds reached $55{\sim}60{\mu}m$ and $75{\sim}80{\mu}m$, respectively. Therefore, there is no significant effect of surface roughness morphology on spot weldability of surface roughness textured galvannealed steel sheets. However, slight difference in thickness of alloying layers existing on electrode tip was found between GA-T and GA-E steels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.183-188
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• 2003

Non-molding and welding line happen by the assembly of gas at the connector terminal. There is not good phenomenon of burr by increasing the over injection pressure, the temperatures of die and resin to prevent from them. Therefore, the connector mold to apply the vacuum molding system is developed in this study. The vacuum pressure is controlled systematically with the optimum conditions in the important ingredients of injection molding that are the temperatures of melting resin and die and cooling condition. The badness in charging is cleared by making a vacuum to non-charging part of the deep bottom part of each cavity. And the vacuum system to reduce the cycle time is applied as the study envelopment of molding work. So, the good product and the productivity improvement can be obtained in this study.