• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.4
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• pp.338-346
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• 1981

Honing, lapping, polishing and superfinishing are applied for a precision machining to finish the metal surface, but these precision machining are micro-cutting by hard and micro-abrasive grains. Frictional machining is the new method to finish mirrorlike surface without using those abrasive grains. The frictional machining produces high pressure and high temperature instantly by compressing a tool material against the metal surface in sliding motion. The metal surface is given plastic deformation and plastic flow by the above mentioned frictional motion, but the surface roughness of the metal surface is influenced by physical and chemical reaction in surrounding atmosphere. Therefore, the atmosphere around the metal optimum atmosphere in the frictional machining. The part 1 of the study was performed in liquid atmospheres. Diesel oil, lubricant, grease, lard oil, bean oil and cutting fluid were used as such atmospheres. Medium carbon steel SM 50 C was used as a workpiece and ceramic tip was applied as a frictional tool. The result of the experiment showed characteristic machining conditions to generate the best surface roughness in each atmospheres.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.257-262
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• 1997

A compact measurement system is developed to measure in-process errors due to thermal deformation of a machine tool, this system is composed of a gauge, 5gap-sensors and a PC. The gauge is made of invar, which is a material that has a very low thermal expansion coefficient. A new neural network model is constructed to estimate thermally induced machine tool errors based on the measured data,the given data,that is a width of cut,a depth of cut, a feed rate, a spindel speed etc, and the calculated data. The detail of the model proposed is described in the paper together with the experimental methodologies using a proposed compact measurement system to examine the validity of the proposed approach.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.5
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• pp.441-446
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• 2015

Chattering during the milling process causes severe problems on both the workpiece and cutting tools. However, chatter vibration is the inevitable phenomenon that operators require the prediction before the process or monitoring system to avoid the chatter in real-time. To predict the chatter vibration with the stability lobe diagram, the dynamic parameters of machine tool are extracted by considering cutting conditions and adapting the material properties. In this study, experimental verifications were taken for various aluminum types with different feed rates to observe the effect of the key parameters. The comparison between experimental results and the predictions was also performed.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.193-198
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• 2005

According to the ISO 14040(1997), Life Cycle Assessment is not the tool only focusing on the emissions from the manufacturing processes of a product, but the tool also expressing environmental adverse impact quantitatively through products entire life cycle (i.e. raw material acquisition, manufacturing, transportation, use, and end-of-life stage). Because the LCA for EMUs(Electrical Multiple Units), however, requires astronomical time and cost for collecting big amount of data. it is inevitable to bring in the simplified LCA methodology, In this study, we introduced standardized methodology of LCA in the world, and found appropriate S-LCA methodology for EMUs. Furthermore, we recommended how to evaluate the environmental impact of EMUs in detail and precisely, using the S-LCA.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.26-29
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• 1999

The sectional forming analysis program for analyzing the hydroforming processes of axisymmetric sheet parts was tleveloped. The rigid-viscoplastic FEM formulation based on membrane theory was derived, wh~cta simi~ltaneously solve force equilibrium as well as non-penetration condition. Hill's non-quadratic normal anisotropic yield theory(1979) was used for material behaviour. For describing the liquid pressure iaction, the flexible tool concept was introduced. Isotropic hardening law was also assumed. To verify the \,alidity of the formulation, the stepped cup forming process as well as the hydrostatic bulging test were \imnlated. Simulation results agreed well with Finckenstein and experimental ones.

• BMB Reports
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• v.34 no.5
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• pp.440-445
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• 2001

Pesticide waste and chemical stockpiles are posing a potential threat to both Vie environment and human health. There is currently a great effort toward developing effective and economical methods for the detoxification of these toxic organophosphates. In terms of safety and economy, enzymatic biodegradation has been recommended as the most promising tool to detoxify these toxic materials. To develop an enzymatic degradation method to detoxify such toxic organophosphorus compounds, a gene encoding organophosphorus acid anhydrolase (OPAA) from genomic DNA of Alteromonas haloplanktis C was subcloned and expressed. The enzyme consists of a single polypeptide chain with a molecular weight of 48 kDa. It demonstrates strong hydrolyzing activity on sarin, an acetylcholinesterase inhibitor. Moreover, its high activity is sustained for a considerable length of time. It is projected that the recombinant OPAA can be applied as an enzymatic tool that can be used not only for the detoxification of pesticide wastes, but also for the demilitarization of chemical stockpiles.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.365-370
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• 1999

SKD11 is one of the most difficult workpiece for machining, so it is necessary to evaluate the machining characteristics of SKD11. The workpiece was made to be the pipe form and heat-treated to HRC45. In this paper, the orthogonal cutting experiment of this material was carried out with TiAlN coated WC cutting tool of 4 kinds of rake angle. After cutting experiment, cutting characteristics of SKD11 were investigated according to variation of cutting speed, feedrate and rake angle.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.54-59
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• 2004

A measure for good products manufactured by grinding process is the surface roughness that is affected by a lot of operating parameters such as types of abrasive, grain size, bond material, wheel speed, table speed, depth of cut, hardness of workpiece and stiffness of grinding machine. In this study, an application of the design of experiments was tried for evaluating the effect of operating parameters on the surface roughness. The workpiece was a high speed tool steel(SKH51) and the surface grinding was conducted. In order to obtain the best surface roughness within constraints of the working range, the optimal grinding conditions were selected. The usefulness of this method was evaluated by the statistical strategy.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.326-331
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• 2000

In this study, residual stress was investigated experimentally to evaluate damaged layer in high-sped machining. In machining difficult-to-cut material, residual stress remaining in machined surface was mainly speared as compressive stress. The scale of this damaged layer depends upon cutting speed, feed per tooth and radial cutting depth. Damaged layer was measured by optical microscope. The micro-structure of damaged layer was a mixed maternsite and austenite. depth of damaged layer is increased with increasing of cutting temperature, cutting force and radial depth. On the other hand, that is slightly decreased with decreasing of cutting force. The increase of tool wear causes a shift of the maximum residual stress in machined surface layer.

• The Journal of Pediatrics of Korean Medicine
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• v.14 no.2
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• pp.121-132
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• 2000

Background : The level of serum eosinophil cationic protein(ECP) is elevated in Atopic Dermatitis patients. Objective : The aim of this study was to investigate the usefulness of serum ECP as a tool of evaluate the efficacy of herb medicine for atopic dermatitis. Material and Method : We investigated 20 patients suffering from atopic dermatitis and analyzed the relationship among the serum level of ECP, IgE, Eosinophil count, and clinical disease activity. Result: Significant elevation in the serum level of ECP, IgE, Eosinophil count is observed in Atopic Dermatitis. Conclusion : The serum level of ECP may be considered to be an useful tool in evaluate effect of herb medicine for atopic dermatitis.