• Proceedings of the KSME Conference
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• 2005.11a
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• pp.146.2-146.2
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• 2005

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.26-29
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• 2000

drawbead expert models are developed for calculating drawbead restraining force and drawbead-exit thinnings which are boundary conditions in FEM stamping simulation employing the linear multiple regression method by which the deviation of drawing characteristics between drawing test and mathematical model is minimized. In order to show the efficiency and accuracy of an expert drawbead model a finite element simulation of auto-body panel stamping is carried out. The finite element simulation shows that the expert drawbead model provides the accurate solution guarantees the stable convergence and the merit in the computation time.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.347-347
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• 2005

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.184-186
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• 2001

Quality estimation of the weld has been one of the important issues in RSW which is a main process of the sheet metal fabrication in auto-body industry. It was well known that among the various welding process variables, dynamic resistance has a close relation with nugget formation. In this study, a new quality estimation algorithm is developed with the primary dynamic resistance measured at welding machine timer. For this, Back propagation algorithm of neural network is used.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1312-1316
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• 2007

Strip casted and rolled magnesium sheet is become exiting material for car manufacturer, due to its better formability and specific strength compare with conventional extruded sheet. TWB technology was attractive for car body designer, because it saves the weight of the car without strength loss. In this study, the laser welding performance of magnesium sheet was investigated for Mg TWB panel manufacturing. The material was strip casted and rolled magnesium alloy sheet contains 3 wt% Al and 1 wt% Zn (AZ31). Lamp pumped Nd:YAG laser of 2kW was used and its laser light was delivered by optical fiber of 0.6mm core diameter to material surface with focusing optics of 200mm focal length for TWB welding. The microstructure of weld bead was investigated to check internal defects such as inclusion, porosity and cracks. Also mechanical properties and formability were evaluated for press forming of car body. For the results, there was no crack but inclusion or porosity on weld at some conditions.The tensile strength of weld was over 95% of base metal. Inner and outer panel of engine hood were press formed and assembled at elevated temperature.

• Journal of the Korean institute of surface engineering
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• v.27 no.4
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• pp.207-214
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• 1994

In consideration of global environmental protection and fuel saving, aluminum alloy sheets for auto body panels such as hood, fender etc., are expected one of the most promising materials for weight saving of cars. The chemical conversion coating is required to prevent the filiform corrosion occurring on painted aluminum. However the conventional process for the composited material mixed with aluminum and steel is complexs; aluminum part is chromated and assembled to the body, and then the steel body undergoes Zn phosphating. In order to overcome the low productivity due to the complex process and the environmental problem with a conventional process, a simultaneous zinc phosphating process for alsuminum and steel in an assembled condition is demanded. Newly developed phosphate solution has been investigated to characterize the phosphating behavior under various conditions. The optimum conditions of the phosphating solution for the application of the paint treatment derived as follows : about 0.3 for the ratio of Zn to $PO_4$, , 200~500 ppm for the concentration of fluoride ion, and 2.5~4.0 for pH. The concentration of dissolved aluminum ion must be kept below 2--ppm and suitable accelerator is found to be a mixture of 1g/$\ell$ $NO_2\;^-$, and 6g/$\ell$ $NO_3\;^-$.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.187-194
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• 2000

Weight reduction for an automobile body is being sought for the fuel efficiency and the energy conservation. One way of the efforts is adopting Ultra Light Steel Auto Body (ULSAB) concept. The ULSAB concept can be used for the light weight of an automobile door with the tailor welded blank (TWB). A design process is defined for the TWB. The inner panel of door is designed by the TWB and optimization. The design starts from an existing component. At first, the hinge and inner reinforcements are removed. In the conceptual design stage, topology optimization is conducted to find the distribution of variable thicknesses. The number of parts and the welding lines are determined from the topology design. In the detailed design process, size optimization is carried out to find thickness while stiffness constraints are satisfied. The final parting lines are determined by shape optimization.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1853-1860
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• 1992

The plane-strain stamping process is analyzed by a forming energy minimization method in order to obtain forming load, slip length and strain distribution in each step of punch stroke. All the developed programs are integrated into total CAD/CAE SYSTEM for the purpose of the practical usage in die design. The computed strain distribution and the amount of draw-in are compared with those of the actually developed panel It is found that there is a good agreement between theoretical and experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.687-692
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• 1993

This paper deals with the generation of laser scan path for manufacturing 3-dimensional body using StereoLithography. The purpose of this study is to develop one module of the StersoLithography system(SLA) for Rapid Protyping and Manufacturing. AutoCAD system is used to supply CAD information from model. The X-Y controller which was made for a special purpose is used to test this system. The system software developed is composed of 3 main modules, the first module is calculating the boundary point os laser scan path. The scound module is generating final output file which is used to down load on the controller. The result of this study shows a good algorithm to generate laser scan path on the basis of simple mathematical background.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.3
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• pp.107-113
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• 1999

The purpose of this study is to analyze multi-size power chuck which can chuck work pieces having various sizes automatically and be used suitably to an exclusive product line in the field of automotive industry. Gripping force, accuracy, and stiffness about the chuck are especially considered for the analysis. MSC/NASTRAN software is used for FEM analysis. Also, the effects of centrifugal force which occurs when chuck body rotates and compressive stresses which occur at contacting area in between chuck body and collet are estimated.