• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2082-2088
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• 2002

Among various methods to manufacture the PDP barrier ribs, the pressing and the roll forming methods are simple and economical because they form the ribs by utilizing the plastic flow of the green tape in a relatively short time without generating air-polluting dusts. In the present study, the roll forming method was investigated by experiments as well as numerical analyses and in result the groove roll and the preform were designed. The effect of draft angle, corner radius, and initial thickness of the green tape on the plastic flow was examined by a series of parametric studies. The preform was recommended to ease the plastic flow into the grooves and to avoid the occurrence of cracks during rolling and sintering processes.

• Journal of Magnetics
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• v.16 no.4
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• pp.440-443
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• 2011

In this study, we investigated the glass-forming ability (GFA) and magnetocaloric effect (MCE) of $Gd_{55}Co_{20}Al_{23}Si_2$ bulk glassy alloy. It is found that the addition of 2 at% Si is effective for extension of the supercooled liquid region (${\Delta}T_x$), the ${\Delta}T_x$ is 55 K for the $Gd_{55}Co_{20}Al_{25}$ glassy alloy, and increases to 79 K for the $Gd_{55}Co_{20}Al_{23}Si_2$ alloy. As a result, $Gd_{55}Co_{20}Al_{23}Si_2$ glassy alloys with diameters up to 5 mm were successfully synthesized. The alloys also exhibit large MCE, i.e., the magnetic entropy change (${\Delta}S_m$) of 8.9 J $kg^{-1}\;K^{-1}$, the full width at half maximum of the ${\Delta}S_m$ (${\delta}T_{FWHM}$) of 87 K, and the refrigerant capacity (RC) of 774 J $kg^{-1}$.

• Environmental Analysis Health and Toxicology
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• v.4 no.1_2
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• pp.67-73
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• 1989

Recently pathotoxicological study of lymphoid organs by administration of some phthalate ester in rats, indicated marked effect of architechure of thymus, spleen, and lymphonodes. Dioctyl phthalate (DOP), one of the phthalate ester, caused statistically significant reduction in the weights of various lymphoid organs. This senstivity of the lymphoid organ to phthalate toxicity which could lead to adverse effects on the immune response and also suppression of immune system. Therfore it is possible the presense of di-(2-ethylhexyl) phthalate (DEHP), one of the phthalate ester as well as DOP, in spleen and other organs might have some moderately effect on the function of the immune system, So our present study was proceeded to assess the effect of DEHP on the immunotoxicity in mouse. In the immune response of DEHP administered mice, HA, HY, Arthus reaction and Rosette forming cell were decreased but DTH was increased. Furthermore, in the DEHP plus ethanol group, HA, HY, Arthus reaction and Rosette forming cell were remarkably decreased and elevation of DTH was inhibited.

• The Journal of Korean Medicine
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• v.23 no.2
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• pp.28-38
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• 2002

Objectives : This study was to examine the efficacy of GCT on the hepatoprotective effect in the liver function and immune octivity. Methods : The experiment to investigate the hepatoprotective effect of GCT on the liver damage was conducted with D-galactosamine. The experiments to verify the effects of GCT on the immune activity were conducted by carbon clearance assay, plaque-forming cell SRBC assay of IgM, lymphoproliferation assay of T and B cells, and adherence and phagocytosis of mocrophages. Results: In the damage of liver induced by D-galactosamine, GCT carried hepatoprotective effect on AST. In carbon clearance assay GCT showed significant effect on phagocytosis of Kuffer cells. In the plaque-forming cell assay, GCT improved the formation of IgM. In the lymphoproliferation assay, GCT activated the formation of T and B lymphocytes. In macrophages, GCT activated adherence and phagocytosis. Conclusion : Though further study is needed, our findings suggest that GCT could be recommended as hepatoprotector and immune modulator for liver disease.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.283-288
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• 2012

Ultra-high-strength steels (UHSSs) are widely used for lightweight automobile parts, and the control of springback is very important in sheet-metal forming. The object of this study is to verify the effects of multi-stage forming process parameters for U-channel-type automobile parts made of UHSS. Finite element analysis is carried out to predict the formability and springback. The main parameters considered for the multi-stage forming process are the die angle, die radius, and punch-forming direction. It is shown that multi-stage forming is very effective for reducing springback, and that a small punch-forming angle and die radius reduce springback, whereas the die angle does not have a large effect.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.199-203
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• 2008

The effects of surface treatment by $O_2$ plasma on the Bio-FETs were investigated by using the pseudo-MOSFETs on the SOI substrates. After a surface treatment by $O_2$ plasma with different RF powers, the current-voltage and field effect mobility of pseudo-MOSFETs were measured by applying back gate bias. The subthreshold characteristics of pseudo-MOSFETs were significantly degraded with increase of RF power. Additionally, a forming gas anneal process in 2 % diluted $H_2/N_2$ ambient was developed to recover the plasma process induced surface damages. A considerable improvement of the subthreshold characteristics was achieved by the forming gas anneal. Therefore, it is concluded that the pseudo-MOSFETs are a powerful tool for monitoring the surface treatment of Bio-FETs and the forming gas anneal process is effective for improving the electrical characteristics of Bio-FETs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.26-29
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• 2008

Recently, the hydroforming of high strength aluminum tubes has many studies and applications in manufacturing industry, especially in automotive industry. But high strength aluminum tube has limited expansion capability at most 15% at normal temperature. New manufacturing process, called hot air forming, is introduced to apply aluminum tube to the automotive sub frame components which have complex shape and require high expansion ratio about 40%. The process is carried out at the elevated temperature above $500^{\circ}C$, so numerous material properties and process parameters related to high temperature should be investigated and determined to get a sound product. In this paper, the hot air forming process of automotive sub frame was investigated. The effect of the forming parameters such as the temperature of tool, axial feeding and gas pressure are analyzes by using explicit finite element method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.452-455
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• 2008

In the present study, blow forming characteristics of commercially roiled AZ31 alloy sheets were investigated. Two different kinds of AZ31 sheets were originally fabricated by using direct casting and strip casting methods respectively. Both sheets have similar grain sizes of about $7{\mu}m$ with a relatively equiaxed structure after rolling. A series of tensile tests were carried out to get flow behavior in terms of temperature and strain rate. Also, grain size effect was investigated by annealing as-received sheet at elevated temperatures. Elongation increased with temperature increment as well expected. However, the differences in tensile test condition did not give much difference in elongation even at the temperature range where a large elongation would be expected with such as fine grain of $7{\mu}m$. Blow forming experiments showed that forming condition did not result in higher difference in dome height. However, the interesting feature from this study was that formability of this AZ31 alloy got different with stress condition. Firstly, biaxial stress condition might result in lower temperature and strain rate dependencies compared to uniaxial tension results for both DC and SC sheets. Secondly, DC showed slower grain growth in uniaxial tension than in biaxial stress state while SC has much higher grain growth rage in uniaxial tension than in bulging.

• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.951-956
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• 2012

This research was carried out in order to discover acid-forming bacteria during fermentation of Makgeolli, as Makgeolli loses its commercial value due to overproduced acidic materials. In Makgeolli kept at $25^{\circ}C$, a sudden increase of acidity as well as the disappearance of yeast cells occurred at day 6, whereas the total cell count and bacterial type remained unchanged; the result implies that a succession of bacterial types, including acid forming bacteria, occurred. Two acid-forming bacteria were isolated from acidified Makgeolli and were identified as Acetobacter pasteurianus and Lactobacillus casei. When fresh and heat-treated Makgeolli were inoculated with Acetobacter pasteurianus and/or Lactobacillus casei, the greatest amount of acid was formed in Makgeolli inoculated with Acetobacter pasteurianus and Lactobacillus casei and also in Makgeolli with Acetobacter pasteurianus alone. This result indicates that Acetobacter pasteurianus is the main acidifier; furthermore, it shows the synergy effect in acid formation with Lactobacillus casei.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.585-588
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented, in this paper The one-step approach using a finite element inverse method will be introduced to predict the optimal forming with changing of blank pressure the developed program is applied to auto-body panel forming.