• Proceedings of the KSME Conference
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• 2001.06a
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• pp.517-522
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• 2001

The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature and stress for 250 hours. Original, aged artificially material were tested to obtain the hardness and impact absorbed energy. Hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1771-1778
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• 2000

The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature for the extended periods. Original, aged artificiall y and used material were tested to obtain the tensile strength, hardness and impact absorbed energy. Tensile strength, hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.515-523
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• 2003

Shape memory is physical phenomenon which a platically metal is restored to its original shape by a solid state phase change by heating. TiNi alloy the most effective material in the shape memory alloy(SMA). To study(measure) recovery stress of intelligent composite. Ti50-Ni50 shape memory matrix with prestrain SMA fiber. When SMA fiber of the intelligent composite is heated over austenite starting temperature(As) by electric heating. a recovery stress are generated. The recovery stress of the intelligent composite was measured by strain gage or photoelastic experiment. Measuring method of recovery stress by photoelastic experiment was developed in this research. It was certified that photoelastic experiment was more effective and more precise than strain gage method in the measurement of recovery stress.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2005.05a
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• pp.50-57
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• 2005

Although the bulk composition of materials is one of the major considerations in extractive metallurgy and environmental science, surface composition and topography (edges and dislocations are preferred sites for physicochemical reactions) control surface reactivity, and consequently play a major role in determining metallurgical phenomena and pollution by heavy metals and organics. An understanding of interaction mechanisms of different chemical species with the mineral surface in an aqueous media is very important in natural environment and metallurgical processing. X-ray photoelectron spectroscopy (XPS) has been used as an ex-situ analytical technique, but the material to be analyzed can be any size from $100{\mu}m$ up to about 1 cm. It can also measure mixed solids powders, but it is impossible to ascertain the original source of resulting x-ray signals where they were emitted from, since it radiates and scans the macro sample surface area.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2002.10a
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• pp.125-134
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• 2002

Crop Protection Products (CPPs) are a useful weapon in our fight against the pests, diseases and weeds that harm or destroy our food. To be effective CPPs need to exhibit some persistence. The consequence of this is that residues of the original material or its metabolites may remain on food and thus there is a potential for the intake of such residues. The issue of CPP residues in food is an emotional subject and is rarely debated rationally or supported by scientific facts. Media headlines like “Poison in our food” or “These days enough Pesticides (CPPs) are sprayed onto vegetables to turn you into one” are testimony to the high level of emotion that surrounds the subject of CPP residues in food. Recent surveys of consumers have indicated that more than 80 percent view CPP residues in food as a “serious hazard”. This significantly exceeds concerns over drugs, hormones in meat, nitrates in food, irradiated foods, food additives, or artificial colours.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.23-30
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• 1996

The purpose of this study was to investigate changes in thewall thickness of tube sinking and working forces by the upper bound method and ABAQUS code. The independent variables were : Workpiece material, original wall thickness of tube, die angle, friction, and diameter reduction. The results indicated that of these five variables were a factor in wall-thickness increase and working forces. Three variables, a inner tube wall angle and two angles of the velocity discontinuous surfaces, are optimized in this proposed velocity field by the upper bound method. In this method, we can estimate the working forces and final tube thicknesses whcih are similar to acturla forming process. Optimized process variables which are obtained by upper bound method are used in ABAQUS pre-model . In ABAQUS analysis, the stress and the strain contours which are considered to be heat generation occured by the friction during forming process are observed.

• Transactions of Materials Processing
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• v.6 no.6
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• pp.517-526
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• 1997

The purpose of this study is to investigate changes in the wall thickness of tube sinking and working forces by the upper bound method and ABAQUS code. The independent variables are ; workpiece material, original wall thickness of tube, die angle, friction, and reduction of diameter. The results indicate that these five variables are factors of the increase in wall-thickness and working forces. Three variables, a inner tube wall angle and two angles of the velocity discontinuous surfaces, are optimized in this proposed velocity field by the upper bound method. In this method, we can estimate the working forces and final tube thicknesses similar to actual forming process. Optimum process variables which are obtained by upper bound method are used in ABAQUS pre-model.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.489-494
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• 2001

The fuel of light water reactor used far several years at high temperature and pressure, so it needs to clad with high corrosion resistance material. The cladding materials need low absorption of a neutron and high corrosion resistance. Cladding materials used Zircaloy-2 in Boiling Water Reactor, Zircaloy-4 in Pressurized Water Reactor and Zirlo has good for long term corrosion. If fracture of cladding tube occured during operation, it caused disaster. So it is needed to estimate of integrity fur cladding materials. In this paper, tension characteristics of cladding materials are investigate which is basic research far fracture characteristic. Also analysis of residual stress effect between tube type(original type) specimen and flattened type specimen.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.304-308
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• 2006

The focus of this study is modeling technique for a bellows in vehicle exhaust system. Bellows was developed using tile finite element model by replacing with the equivalent beam. The equivalent beam model were studied in detail. Non-structural node in the cross section of original model is given to expressing their motion. Equivalent mass matrix and stiffness matrix calculated using Guyan reduction method. Material Properties of beam was obtained from the direct comparison between equivalent model and that of Timoshenko beam model. The calculated natural frequencies and mode shape are compared with the reference results and coincided well. The results were compared with the confirmed results, which were in good agreement.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.143-149
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• 2005

In this paper we propose a novel volume hologram encryption system with binary amplitude masks rather than phase masks, in which volume holograms can be securely recorded against the attacks by a third party. In our system, the encryption is done by multiplexing two volume holograms in such a way that an original binary data page is first stored as a volume hologram by interference with a binary amplitude mask and then the complementary data page is stored as another volume hologram by interference with the complementary binary amplitude mask over the first hologram. The operation principle of our system is explained with the well-known theory of recording and reading a volume hologram in a photorefractive material and the experimental results are presented. Experimental data show that our encryption system is protected from blind decryptions by randomly-generated incorrect amplitude masks.