• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.54-55
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• 2001

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.7-15
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• 2002

In this paper, the nonlinear parameter estimation method using the estimated hysteresis of each structural members was studied for the purpose of efficient seismic damage prediction and estimation of MDOF nonlinear structural model in the shaking table test. The hysteresis of each structural members can be obtained by the conversion of measured response histories into relative motions of each structural members and member forces. These hysteresis can be used to evaluate various kinds of damage indices of each structural members. The MDOF nonlinear structural model for further analysis(re-analysis) can be easily reconstructed using estimated nonlinear structural parameters of each structural members. To demonstrate the proposed techniques, several numerical and experimental example analyses are carried out. The results indicate that the proposed method can be very useful to assess local seismic damages of structures.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.619-626
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• 2008

In this study, design methodology to determine optimal shape of the anvil in sizing press process has been proposed to minimize crop length of the AISI 1010 slab in horizontal rolling after width reduction. Shape of anvil were selected to 12 cases by design of experiment, and the dog-bone shapes and the crop length were determined by FE-analysis. Also, the anvil shape, which has minimum crop length, were determined by artificial neural network(ANN). As a result of FE-analysis, it can be seen that the crop length was increased with increasing center thickness in the dog-bone shape after width reduction. The anvil shape which has minimum crop length, was estimated to ${\theta}_{1}=21^{\circ}{\theta}_{2}=14^{\circ}$ by FE-analysis and ANN.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.223-225
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• 2007

Online models predicting roll force and forward slip of roughing mill was developed using nondimensional parameters. Using the effective inlet thickness, roll force model take into account the effect of inlet dog-bone shape of slab which take places after width reduction through edger rolling in roughing mill. The prediction accuracy of the proposed model is examined through comparison with measurements.

• Transactions of Materials Processing
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• v.12 no.2
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• pp.151-160
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• 2003

In the present study, an advanced surface construction method based on NURBS surface scheme is proposed to construct the extrusion die surface. The inlet and outlet profiles we precisely described with NURBS curves using the cubic appropriate control points and weights. The interior control Points of surface are generated using the cubic interpolation of the weights at the inlet and outlet sections. In order to verify of the proposed method, automatic surface generation is carried out for the various types of extrusion die surface.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.06a
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• pp.185-189
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• 1994

The key factor of quality in precision metal forming is to meet the requirements of parts size and shape. Particular problem of unflatness occurs frequently. This study focuses on figuring out the cause of unflatness. To predict the amount of unflatness after ejection from tool, equivalent temperature method is used. This method, temperature equivalent to the final stress value is calculated, and it is applied as the boundary condition of the linear static analysis. The final of formed part is used as the geometry model of the static analysis.

• Transactions of Materials Processing
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• v.3 no.4
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• pp.468-481
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• 1994

Mathematical description of arbitrarily-shaped tool surface are introduced by parametric patch approaches along with the related contact search algorithm. In order to maintain the advantages of membrane elements and to incoporate the bending effect, a BEAM(Bending Energy Augmented Membrane) element is proposed. Computation are carried out for some complex axisymmetric multi-stage deep drawing to verify the validity and the effectiveness of the proposed method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.03a
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• pp.211-223
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• 1995

The purpose of the present study is to examine shearing mechanism through rigidplastic finite element analysis. Difficulties arise in simulating shearing process due tothe narrow shear band formation andlackof proper fracture resolve these difficulties by using adaptive mesh generation crriterion. The simulation results are obtained for various punch clearances and these are compared with existing experimental results. It is shown that FEM simulation technique can be used to further understand the shearing mechanism.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.110-120
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• 1998

Tailor-welded blanks are made of two or more different blanks in thickness or material. So car body with tailor-welded blanks need not reinforcement panels. However in order to make stamping tools for tailor-welded blanks, die engineers should know about the exact position of the welding line after the part is drawn. The necessity of knowledge about the position of welding line needs forming simulation methodology as a prior step in tooling. Therefor some parts of the simulation methodology are proposed and compared with the experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.718-725
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• 2016

In this study, the plastic flow curve of commercially pure titanium sheet (CP Ti) actively used in the plate heat exchanger etc., was evaluated. The plastic flow curve known as hardening curve is a key factor needed in conducting finite element analyses (FEA) for the forming process of a sheet material. A hydraulic bulge test was performed on the CP Ti sheet and the strain in this test was measured using the DIC method and ARAMIS system. The measured true stress-true strain curve from the hydraulic bulge test (HBT) was compared with that from the tensile test. The measured true stress-true strain curve from the hydraulic bulge test showed stable plastic flow curve over the strain range of 0.7 which cannot be obtained in the case of the uniaxial tensile test. The measured true stress-true strain curve from the hydraulic bulge test can be fitted well by the hardening equation known as the Kim-Tuan model.