• Textile Coloration and Finishing
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• v.15 no.3
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• pp.176-184
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• 2003

This research aimed at scrutinizing the dyeability of some solvent dyes on polyester and their light fastness to be exploited as a breakthrough in light fastness where utmost fastness is required such as ultramicrofibers and industrial markets. Dyeability on polyester was mainly evaluated by HT exhaust dyeing according to the general procedure. Light fastness has been tested by a preliminary UV test followed by HT xenon test in compliance with standard SAE J1885, 224 KJ. Fading has been determined quantitatively by evaluating the shade deviation and the strength difference between unexposed and exposed samples by means of CIELab values.

• Bulletin of the Korean Chemical Society
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• v.5 no.2
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• pp.79-82
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• 1984

This study concerns about catalyic cracking of iso-octane over cation ($Cd^{2+},\;Ca^{2+}\;and\;La^{3+}$) exchange mordenites. It deals with mordenite shape selectivity and with kinetics of this catalytic reaction. The striking feature was that over the region of cracking temperature investigated, 523-665K, the yield of isobutene was predominant, relative to that of larger or smaller carbon chain(s). This permits kinetic analysis of the heterogeneous catalytic system in terms of the modified pulse-version microcatalytic chromatography. The observed activation energy ($E_a,\;KJ\;mol^{-1}$) was found to be 46 for Cd-M, 57 for Ca-M and 59 for La-M, respectively.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.261-265
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• 1992

To improve preservation and utilization of radish juice concentrates, radish juice were concentrated by reverse osmosis(RO) and thin layer evaporator(TLE) and their rheological properties were investigated. Radish juice concentrates were considered as nowtonian fluids. The apparent viscosity of conc. 1 (Heat treatment radish juice, concentrated by TLE), conc. 2 (Raw radish juice, concentrated by TLE), conc. 3 (Heat treatment radish juice, concentrated by RO) were 0.0503, 0.0578 and 0.0655 Pa.s at 10(1/s), respectively. The yield stress of these concentrates were ranged from 0.0001 to 0.0580 Pa. The activation energy for the flow of the radish juice conc. 1 were increased from 2.7057 to $4.1159{\times}10^4KJ/kg.mol$ by increasing concentration of radish juice.

• Journal of the Korean Ceramic Society
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• v.35 no.1
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• pp.55-65
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• 1998

The oxidation behavior of Ag-36.8a%Cu-7.4at%Ti alloy brazed on Si3N4 substrate was investigated at 400, 500 and 600$^{\circ}C$ in air. Under this experimental condition Si3N4 and Ag were not oxidized whereas Cu and Ti among the brazing alloy components were oxidizied obeying the parabolic oxidation rate law. The activation energy of oxidation was found to be 80kj/ mol which was smaller than that of pure Cu owing to the presence of oxygen active element of Ti. The outer oxide scale formed from the initial oxidation state was always composed of Cu oxides which were known to be growing by the outward diffusion of Cu ions. As the oxidation progressed the concentration gradient occurred due to the continuous consumption of Cu as Cu oxides and consequently build-up of an Ag-enriched layer below the Cu oxides resulted in the formation of multiple oxide scales composed of Cu oxide (CuO) /Ag-enriched layer/Cu oxide (Cu2O) /Ag-enriched layer. Also the inward diffusing of oxygen through Cu oxide and Ag-enriched layers led to the formation of internal oxides of TiO2.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.4
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• pp.520-526
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• 2013

To determine the kimchi with the best quality and functional characteristics, we manufactured and compared recipes for Korean and Japanese kimchi made either Korean or Japanese baechu cabbages. All batches were fermented for 4 weeks at $5^{\circ}C$, and tested for pH, texture, microbial count, sensory evaluation, DPPH radical-scavenging activity, and cell proliferation (using the MTT assay on AGS human gastric cancer cells). By the third week of fermentation, Korean kimchi made with Korean baechu (KK) and Japanese kimchi made with Korean baechu (KJ) showed a higher acidity than Korean or Japanese kimchi made with Japanese baechu (JK and JJ, respectively). KK ranked highest in springiness, followed by KJ, JK, and JJ. Therefore, the texture of kimchi produced with Korean baechu was appears better than kimchi produced with Japanese baechu. This was confirmed in masticatory tests. Kimchi produced with Korean baechu (KK and KJ) showed lower total aerobic bacterial counts, while the total lactic acid bacterial counts were higher (p<0.05). In sensory evaluation test, KK received the highest overall acceptability score, while JJ earned the lowest score. In the DPPH assay for anti-oxidative activity, KK showed a 94% anti-oxidative effect, followed by KJ (92%), JK (91%), and JJ (88%) (p<0.05). In the MTT assay for analyzing the cell proliferation of AGS human gastric cancer cells, KK showed a 64% anticancer effect in vitro, followed by KJ (57%), JK (38%), and JJ (26%). Therefore, the anti-oxidative and anti-cancer functionalities of kimchi made with Korean baechu were higher than those made with Japanese baechu, regardless of the kimchi recipe applied. Overall, Korean baechu had important and superior effects on the quality and functionality of kimchi.

• Journal of Biosystems Engineering
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• v.15 no.1
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• pp.14-22
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• 1990

For efficient use of solar energy in plastic greenhouse, thermal storage system was developed. The system was constructed with the counter-flow type air-water heat exchanger using a thin polyethylene film as a medium of heat exchange parts. Experiments were carried out to investigate the heat exchange rate, optimum water flow rate, overall heat transfer coefficient, and the effectiveness of the counter-flow type air-water heat exchanger with polyethylene film bags. Mathematical model to predict air temperature leaving heat exchanger was developed. The results obtained in the present study are summarized as follows. 1. Heat exchange rate in the counter-flow type air-water heat exchanger with polyethylene film bags was compared to that of polyethylene film. Heat exchange rate was almost identical at air velocity of 0.5m/s on polyethylene film surface. But, heat exchange rate of heat exchanger with polyethylene film bag was $32{\sim}55KJ/m^2$ hr higher than that of polyethylene film at air velocity of 1.0m/s. 2. Considering the formation of uniform water film and the sufficient heat exchange rate of polyethylene film bags, optimum water flow rate in polyethylene film bags was $3.0{\sim}6.0{\ell}/m^2$ min. 3. The overall heat transfer coefficient of polyethylene film bags was found to be $35.0{\sim}130.0KJ/m^2\;hr\;^{\circ}C$ corresponding to the air velocity ranging 0.5 to 4.0 m/s on polyethylene film surface. And the overall heat transfer coefficient showed almost linearly increasing tendency to the variation of air velocity. 4. Mathematical model to predict air temperature leaving the heat exchanger was developed, resulting in a good agreement between the experimental and predicted values. But, the experimental results were a little lower than predicted. 5. Effectiveness of heat exchanger for the experiment was found to be 0.40~0.81 corresponding to the number of transfer units due to the variation of air velocity ranging 0.6 to 1.7 m/s.

• Journal of the Korean Ceramic Society
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• v.16 no.4
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• pp.213-224
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• 1979

The present work was undertaken: (1) to determine if CaO-partially stabilized $ZrO_2$ prepared by Hot Petroleum Drying Method would show better ionic conductor as an oxygen sensor in molten metals than that prepared by Oxide Wet Mixing Method and than CaO-fully stabilized $ZrO_2$, and (2) to understand the nature of conduction mechanism of CaO-partially stabilized $ZrO_2$ by a comparison of measured electrical conductivity data with theory on defect structure of pure monoclinic $ZrO_2$ and fully stabilized cubic $ZrO_2$. The DC electrical conductivity was measured by 3-probe technique and the AC electrical conductivity by 2-probe technique as a function of temperature in the range 973-1373 K and oxygen partial pressure in the range 10-1-10-25Mpa. The results of the experiments were as follows: 1. CaO-partially stabilized $ZrO_2$ prepared by Hot petroleum Drying Method showed at T=1094-1285 K and $Po_2$=10-7-10-25 MPa a nearly ionic conduction with 4 times higher conductivity than that prepared by Oxide Wet Mixing Method. 2. High-oxygen pressure conductivity tends toward a Po_2^{+1/5}-Po_2^{+1/6}$dependence. An analysis of possible defect structures suggests that CaO-partially stabilized $ZrO_2$ has an anti-Frenkel defect in which singly or doubly ionized oxygen interstitials and defect electrons predominate at T=1094-1285 K and $Po_2$=10-1-10-7MPa. 3. The activation energy for pure electron hole-conduction and ionic conduction of CaO-partially stabilized $ZrO_2$ was found to be 130 KJ/mol at T=973-1373 K, $Po_2$=2, 127 10-2 MPa(air) and 153KJ/mol at T=1094-1285 K respectively.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.185-190
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• 1992

Near-IR spectra for $ν_{\alpha}$+ Amide Ⅱ combination band of thioamides, and very dilute thioamide-DMSO solution in CCl4 were recorded in the temperature range of $5^{\circ}C$ to $55^{\circ}C$. This combination band was resolved by the computer program into two Lorentzian-Gaussian product function which have been identified with monomeric thioamide and thioamide-DMSO 1 : 1 complex. Equilibrium constants and thermodynamic parameters for the thioamide-DMSO hydrogen bonding were elucidated by the analysis of conce ntration and temperature dependent spectra. The hydrogen bonding strength between thioacetamide (TA) and DMSO in $CCl_4$ is stronger than that between thiopropionamide (TPA) and DMSO in CCl4. The ${\Delta}H^{\circ}$ for the TA-DMSO and TPA-DMSO 1 : 1 complex in CCl4 were -15.3 kJ${\cdot}$$mol^{-1}$ and -14.2 kj${\cdot}$$mol^{-1}$, respectively.

• Journal of the Korean Chemical Society
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• v.30 no.6
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• pp.510-515
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• 1986

Spectra for the $v_3$+ Amide II combination band of thioacetamide(TA) were obtained in carbon tetrachloride solutions and in very dilute solutions of TA-N,N-dimethlylacetamide (DMA) in carbon tetrachloride in the range of 5~55$^{\circ}$C. The combination band in the three component system can be resolved into components due to monomeric TA, 1 : 1 TA-DMA complex and 1 : 2 TA-DMA complex. In the dilute solutions the experimental spectrum was resolved by using the computer into its two Lorentzian-Gaussian product components which have been identified with the monomeric TA and the 1 : 1 complex. The equilibrium constants and thermodynamic parameters of 1 : 1 complex were determined by analysis of concentration and temperature dependent spectra. The ${\Delta}H^{\circ}$ and ${\Delta}S^{\circ}$ for the 1 : 1 complex were -14.4 KJ mol$^{-1}$ and -15.6 J mol$^{-1}deg^{-1}$, respectively.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.828-836
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• 1994

In order to investigate the high temperature deformation characteristics in YBaiCu307-, oxide superconductor, the compression test was performed at temperatures from $890^{\circ}C$ to $930^{\circ}C$ at initial strain rate between $1.0 x 10^{-5}s^{-1}\; and \; 1.0^{-4}s^{-1}$. As the temperature increased and the initial strain rate decreased, the flow stress decreased. The strain rate sensitivity exponent measured as 0.41-0.46, supporting occurence of a superplastic deformation. The activation energy for superplastic deformation was calculated as 500-580KJ/mol, which decreased with increasing Ag content. Microstructure of the superplastically-deformed specimens showed that a grain growth occurred during deformation, and it appeared to be considerable when Ag content increased, but most grains still remained equiaxed after deformation. In this study, the deformation mechanism of YBCO superconductor was the grain boundary sliding with the diffusional accommodation and the contribution of the gram boundary sliding to the total strain was estimated to be 65%.