• Transactions of Materials Processing
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• v.13 no.2
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• pp.168-173
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• 2004

Microforming can be a good application for bulk metallic glasses. It is important to simulate the deformation behaviour of the bulk metallic glasses in a supercooled liquid region for manufacturing micromachine parts. For these purposes, a correct constitutive model which can reproduce viscosity results is essential for good predicting capability. In this paper, we studied deformation behaviour of the bulk metallic glasses using the finite element method in conjunction with the fictive stress constitutive model which can describe non-Newtonian as well as Newtonian behaviour. A combination of kinetic equation which describes the mechanical response of the bulk metallic glasses at a given temperature and evolution equations fur internal variables provide the constitutive equation of the fictive stress model. The internal variables are associated with fictive stress and relation time. The model has a modular structure and can be adjusted to describe a particular type of microforming process. Implementation of the model into the MARC software has shown its versatility and good predictive capability.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.528-538
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• 1996

A magent console is critical element since its homogeneity is essential to the performance of a nuclear magnetic resonance (NMR) based sensor. Geometry and properties of magnet materials determine the magnetic flux density and homogeneity of the console. This study is carried out to develop a design scheme of the magnet console using ANSYS to reduce the design error of the magnet console compared . To enhance the performance of the magnet console, corner steel was proposed and validated by simulation and manufactured one. The corner steel increased the magnetic flux density (B) by about 1% and enhanced homogeneity by approximately 3 times. There was about 3% difference between simulated and measured B values.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.11-16
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• 1997

In this study, the finite element analysis of AA6061 wheel forging processes over hot working range is performed and a thermo-viscoplasticity theory applicable to hot forging is applied for simulation. Aluminum alloy has frequently been utilized to manufacture automobile and aircraft parts due to its various advantages such as lightness, good forgeability, and wear resistance. Several forging conditions are applied to the simulation, such as die speeds, rib thicknesses, and depth of die cavity. The effectiveness of the simulation results is summarized in terms of metal flow, strain distributions, temperature distributions, forging load, which are essential to over all process design.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.141-150
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• 1998

The measurement of strains in stamped sheet metal is essential to the design and manufacture of sound sheet metal products. The measured strains can also be used in verifying the reliability of the computer analysis such as finite element analysis. In most engineering applications, strains are measured from the deformed square grids or deformed circular grids in comparison with the initial undeformed grids. In such a case, however, strains are averaged in each grid and the localized strain in a region smaller than a grid size can not be measured. In the present study, the B-spline surface interpolation technique is introduced in order to measure the strains more exactly and effectively. The strains calculated by using the surface interpolation technique are compared with the strains calculated from the three-noded grids as well as with the finite element analysis.

• Nuclear Engineering and Technology
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• v.46 no.5
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• pp.689-698
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• 2014

Reactor internals are sensitive to dynamic loads such as earthquakes and flow induced vibration. Thus, it is essential to identify the dynamic characteristics to evaluate the seismic integrity of the structures. However, a full-sized system is too large to perform modal experiments, making it difficult to extract data on its modal characteristics. In this research, we constructed a finite element model of the APR1400 reactor internals to identify their modal characteristics. The commercial reactor was selected to reflect the actual boundary conditions. Our FE model was constructed based on scale-similarity analysis and fluid-structure interaction investigations using a fabricated scaled-down model.

• Molecules and Cells
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• v.20 no.2
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• pp.167-172
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• 2005

Ceruloplasmin (Cp) is a copper protein with important functions in iron homeostasis and in inflammation. Cp mRNA expression is induced by interferon (IFN)-${\gamma}$ in U937 monocytic cells, but synthesis of Cp protein is halted after about 12 h by transcript-specific translational silencing. The silencing mechanism requires binding of a 4-component cytosolic inhibitor complex, IFN-gamma-activated inhibitor of translation (GAIT), to a defined structural element (GAIT element) in the Cp 3'-UTR. Translational silencing of Cp mRNA requires the essential proteins of mRNA circularization, suggesting that the translational inhibition requires end-to-end mRNA closure. These studies describe a new mechanism of translational control, and may shed light on the role that macrophage-derived Cp plays at the intersection of iron homeostasis and inflammation.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1089-1094
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• 2004

Numerical methods to estimate behaviors of jointed rock mass can be roughly divided into two method : discontinuous model and continuum model. Generally, distinct element method (DEM) is applied in discontinuous model, and finite element method (FEM) or finite difference method (FDM) is utilized in continuum model. To predict a behavior of discontinuous model by DEM, it is essential to understand characteristics of joints developed in rock mass through field tests. However, results of field tests can not provide full information about rock mass because field tests is conducted in limited area. In this paper, discontinuous analysis by UDEC and continuous analysis by FLAC is utilized to estimate a behavior of a tunnel in jointed rock mass. For including discontinuous analysis in continuous analysis, joints in rock mass is considered by reducing rock mass properties obtained by RMR and decreasing shear strength of rock mass. By comparing and revising two analysis results, analysis results similar with practical behavior of a tunnel can be induced and appropriate support system is decided.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.197-202
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• 2005

An aspheric lens is one of a key point optical element in the optical industry. The feature of an aspheric lens is not to have the spherical aberration. An aspheric lens is also essential element for high-precision and light-weight in the optical machine. Generally it have been used in a tailor progression an aspheric lens modelling much. In this study we applied a lay back-tracer using a index of refraction to draw a creative aspheric lens. Also we developed the automatic design program for aspheric lens. We manufactured the aspheric lens and executed a comparison experiment for refraction situation of shape and straightness experiment to inspect the drawn aspheric lens in this study.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.234-238
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• 2005

One approach to testing the suitability of a adhesive joint for a particular application is to build and test to destruction of a representative sample of the joint. The nondestructive test will not measure strength directly but will measure a parameter which can be correlated to the strength. It is therefore, essential that a suitable nondestructive test is chosen and its results are correctly interpreted. In this paper, typical ultrasonic signal analysis in adhesive joints are evaluated together with interface stress from the result of finite element analysis.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.780-786
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• 2013

In the reliability-based design optimization of electromagnetic devices, the accurate and efficient reliability assessment method is very essential. The first-order sensitivity-assisted Monte Carlo Simulation is proposed in the former research. In order to improve its accuracy for wide application, in this paper, the second-order sensitivity analysis is presented by using the hybrid direct differentiation-adjoint variable method incorporated with the finite element method. By combining the second-order sensitivity with the Monte Carlo Simulation method, the second-order sensitivity-assisted Monte Carlo Simulation algorithm is proposed to implement reliability calculation. Through application to one superconductor magnetic energy storage system, its accuracy is validated by comparing calculation results with other methods.