• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.211-214
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• 2004

In the present study, the effect of SIDT (Strain Induced Dynamic Transformation) on the microstructure of medium carbon steels was investigated to develop spheroidized annealing-free steel wire rods. When $0.45\%C$ steels were hot-deformed under the conditions of heavy reduction at low temperatures, a microstructure quite different from conventional ferrite-pearlite structure was obtained. It was considered that this ferrite-cementite microstructure was obtained because very small retained austenite grains existing between fine SIDT ferrites prefer to transform to cementite and ferrite instead of pearlite during cooling. Through the present study, $0.45\%C$ steels containing ferrite-cementite (FC) structure instead of ferrite-pearlite structure was obtained in as-rolled state by introducing SIDT. The specimen containing the FC structure was much softer than that containing conventional ferrite-pearlite structure. Therefore, it is concluded that deforming medium carbon steels under the conditions of SIDT is a very powerful method to obtain soft steel wire rods which could be cold-forged without softening heat-treatment

• Korean Journal of Materials Research
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• v.14 no.12
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• pp.863-869
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• 2004

The purpose of this research is to investigate the mechanical property and ductile-brittle transition temperature of Ti-Nb-P added extra low carbon interstitial free steel having a tensile strength of 440 MPa. The mechanical property and transition temperature of hot rolled steel sheets were more influenced by the coiling temperature rather than by the small amount of alloying element. Further, at the same composition, the property of the specimen coiled at low temperature was superior to that obtained at higher coiling temperature. The fracture surface of 0.005C-0.2Si-1.43Mn steel coiled at $630^{\circ}C$ showed a ductile fracture mode at $-100^{\circ}C$, but coiling at $670^{\circ}C$ showed a transgranular brittle fracture mode at $-90^{\circ}C$. The galvannealed 0.006C-0.07Si-1.33Mn steel sheet annealed at $810^{\circ}C$ has tensile strength and elongation of 442.8 MPa and $36.6\%$, respectively. The transition temperature of galvannealed 0.006C-0.07Si-1.33Mn steel sheet was increased with a drawing ratio, and the transition temperature of the galvannealed 0.006C-0.07Si-1.33Mn steel was $-60^{\circ}C$ at a drawing ratio of 1.8

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.402-406
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• 2008

A series of random copolymers, composed of 1H,1H,2H,2H-perfluoro decyl methacrylate (FDMA) as a $CO_2$-philic monomer and tert-butyl methacrylate (TBMA) as an acid labile monomer, were synthesized by free radical polymerization. The solubility of copolymers in carbon dioxide, light sensitivity at 365 nm exposure, and photoresist pattern formation properties were investigated. Furthermore, sub micron-sized poly(styrenesulfonate) : poly(3,4-ethylenedioxythiophene) (PSS : PEDOT) conducting polymer patterns were successfully prepared by pattern transfer.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.590-598
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• 2016

In this study, the adsorption behavior from aqueous solution as well as kinetic and thermodynamic parameters of Acid Black 1 were investigated through batch reaction using coconut shell based granular steam activated carbon. The effects of various adsorption parameters such as pH, initial concentration, contact time, temperature were studied. To confirm the effect of pH, pHpzc measurements were analyzed followed by measuring removal efficiencies of Acid Black 1 at the pH range from 3 to 11. Experimental equilibrium adsorption data were fitted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption isotherm. The conformity of adsorption reaction for pseudo first and second order model were evaluated through kinetic analysis. Values of enthalpy change and activation energy were also investigated through thermodynamic analysis and it was confirmed that the adsorption process was endothermic. The spontaneity of adsorption process was evaluated using the values of entropy and Gibbs free energy changes.

• Food Science of Animal Resources
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• v.37 no.1
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• pp.29-37
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• 2017

Defatted bovine liver (DBL) is a potential source of protein and minerals. Supercritical carbon dioxide ($SC-CO_2$) and a traditional organic solvent method were used to remove lipid from bovine liver, and the quality characteristics of a control bovine liver (CBL), bovine liver defatted by $SC-CO_2$ ($DBLSC-CO_2$) at different pressures, and bovine liver defatted by organic solvent (DBL-OS) were compared. The $DBLSC-CO_2$ samples had significantly higher (p<0.05) protein, amino acid, carbohydrate, and fiber contents than CBL and DBL-OS. There was a higher yield of lipid from CBL when using $SC-CO_2$ than the organic solvent method. SDS-PAGE analysis demonstrated that the CBL and $DBLSC-CO_2$ had protein bands of a similar intensity and area, whereas DBL-OS appeared extremely poor bands or no bands due to the degradation of proteins, particularly in the 50 to 75 kDa and 20 to 25 kDa molecular weight ranges. In addition, $DBLSC-CO_2$ was shown to have superior functional properties in terms of total soluble content, water and oil absorption, and foaming and emulsification properties. Therefore, $SC-CO_2$ treatment offers a nutritionally and environmentally friendly approach for the removal of lipid from high protein food sources. In addition, $SC-CO_2$ may be a better substitute of traditional organic solvent extraction for producing more stable and high quality foods with high-protein, fat-free, and low calorie contents.

• Polymer(Korea)
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• v.35 no.5
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• pp.451-457
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• 2011

The effect of latex particle size on rheological and electrical properties of latex-blended polystyrene (PS)/multi-walled carbon nanotube (MWCNT) nanocomposites was investigated. Mono-dispersed PS particles synthesized either by emulsifier-free emulsion polymerization or by dispersion polymerization were mixed with MWCNTs under ultrasonication, and freeze-dried to prepare the nanocomposites. As the MWCNT content increased, storage modulus, complex viscosity and electrical conductivity were substantially increased. The increase of storage modulus and complex viscosity was higher for larger PS particles. The effect of particle size on electrical properties was different depending on MWCNT content. With lower MWCNT content, the nanocomposite prepared by smaller PS particles showed higher electrical conductivity, but the opposite result was given as the content increased.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.114-118
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• 2001

The present study was undertaken to investigate whether or not the hepatoprotective activity of acetylbergenin was superior to bergenin in carbon tetrachloride ($CCl_4$)-intoxicated rat. Acetylbergenin was synthesized by acetylating bergenin, which was isolated from Mallotus japonicus. The hepatoprotective effects of acetylbergenin were examined against $CCl_4$-induced liver damage in rats by means of serum and liver biochemical Indices. Acetylbergenin was administered orally once daily for 7 successive days, then a 0.5 ${m/kg}$ mixture of $CCl_4$in olive oil (1:1) was intraperitoneally injected at 12 h and 36 h after the final administration of acetylbergenin. Pretreatment with acetylbergenin reduced the elevated serum enzymatic activities of alanine/aspartate aminotransferase, sorbitol dehydrogenase and $\gamma$-glutamyltransferase in a dose dependent fashion. Acetylbergenin also prevented the elevation of hepatic malondialdehyde formation and depletion of glutathione content dose dependently in $CCl_4$-intoxicates rats. In addition, the decreased activities of glutathione S-transferase and glutathione reductase were restored to almost normal levels. The results of this study strongly suggest that acetylbergenin n has potent hepatoprotective activity against $CCl_4$-induced hepatic damage in rats by glutathione-mediated detoxification as well as having free radical scavenging activity. In addition, acetylbergenin doses of 50 ${mg/kg}$showed almost the same levels of hepatoprotection activity as 100 ${mg/kg}$ of bergenin, indicating that lipophilic acetylbergenin is more active against the antihepatotoxic effects of $CCl_4$ than those of the much less lipophilic bergenin.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.414-419
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• 1995

${\beta}-carotene$ was extracted from freeze-dried carrot by supercritical carbon dioxide $(SC-CO_2)$ and mixtures of $CO_2$ doped with ethanol or methanol as a cosolvent at temperatures of 40 to $60^{\circ}C$ and pressures of 138 to 276 bar. Solubility of ${\beta}-carotene$ in $SC-CO_2$ increased with the increase of extraction pressure and the decrease of extraction temperature. The highest solubility observed was $4.90\;{\mu}g/g\;CO_2\;for\;{\alpha}-carotene\;and\;0.604\;{\mu}g/g\;CO_2$ for ${\alpha}-carotene\;at\;40^{\circ}C$ and 276 bar. Addition of ethanol increased the solubility being the largest increase of 82% using a mixture of $CO_2$ and 17.4% ethanol. $SC-CO_2$ extraction can be used to selectively obtain natural carotenoids, free of solvent residuals, which can be used as food additives.

• Preventive Nutrition and Food Science
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• v.8 no.2
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• pp.130-136
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• 2003

The protective effects of onion extract (OE), onion powder extracted in ethanol for 2 days. on carbon tetrachloride ($CCl_4$)-induced hepatotoxicities and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with OE prior to the administration of $CCl_4$ significantly reduced the increase in serum alanine and aspartate aminotransferase activities and hepatic lipid peroxidation in a dose-dependent manner. In addition, pretreatment with OE significantly prevented the depletion of reduced glutathione content in the liver of $CCl_4$-intoxicated mice. $CCl_4$-induced hepatotoxicity was also prevented, as indicated by a liver histopathologic findings. The effects of OE on the cytochrome P450 (P450) 2E1, the major isozyme involved in $CCl_4$ biotransformation were investigated. Treatment of mice with OE resulted in a significant decrease in P450 2E1-dependent p-nitrophenol and aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. OE also exhibited antioxidant effects in FeCl$_2$-ascorbate induced lipid peroxidation in rat liver homogenates and in superoxide radical scavenging activity. These results show that the protective effects of OE against the $CCl_4$-induced hepatotoxicity may be due to its ability to block bioactivation of $CCl_4$, mainly tty inhibiting the expression and activities of P450 2E1 and by scavenging free radicals.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.182-185
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• 2004

In this work, the effect of chemical treatments on surface properties of SiC was investigated in mechanical interfacial properties of carbon fibers-reinforced composites. The surface properties of the SiC were determined by acid/base values and contact angles. The thermal stabilities of carbon fibers-reinforced composites were investigated by thermogravimetric analysis (TGA). Also, the mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical strain energy release rate mode II $(G_{IIC})$ measurements. As a result, tile acidically treated SiC (A-SiC) had higher acid value than that of untreated SiC (V-SiC) or basically treated SiC (B-SiC). According to the contact angle measurements, it was observed that chemical treatments led to an increase of surface free energy of the SiC surfaces, mainly due to the increase of the specific (polar) component. The mechanical interfacial properties of the composites, including ILSS and $(G_{IIC})$, had been improved in the specimens treated by chemical solutions. These results were explained that good wetting played an important role in improving the degree of adhesion at interfaces between SiC and epoxy resin matrix.