• The Korean Journal of Food And Nutrition
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• 제7권1호
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• pp.1-7
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• 1994

To investigate the characteristics of active sites of the D-xylanase and $\beta$-xylosidase purified from Penicillium verruculosum, effects of various chemicals on the enzyme activity were analyzed. The D-xylanase was activated by Cua), however it was inhibited by metal ions, Hg2+ and Mna+, by chemicals, N-bromosuccinimide, iodine, diethylpyrocarbonate, and 2,3-butanedione. These results suggested that the D-xylanase from Penicillium verruculosum contained tyrosine, histidine, arginine and tryptophan at the active center. The $\beta$-xylosidase was inhibited by Hg2+, N-bromosuccinimide and sodium dodecyl sulfate, however it was not effected by Mn2+ and Cu2). It was suggested that the enzyme contained tryptophan at the active center.

• Journal of the Korean Ceramic Society
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• 제36권7호
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• pp.725-733
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• 1999

It is a fundamental experiment to use blast-furnace slag in solidification/stabilization process. The compressive strength and leaching test of Pb and Cr doped samples were evaluated and the effects of heavy-metal ions on the hydration of slag was investigated. Sodium silicates(5wt%) was added as alkali-activator and the effects of replacing a part of slag with flyash or gypsum was also discussed. Pb ion was solidified by encapsulation of matrix. In of slag${\pm}$gypsum binder microstructure was densified by accelerating to form AFt/AFm phase and compressive strength was improved resulting in reducing leaching amount of Pb ion. Cr ion was solidified by substituting with Al ion in aluminate product. Slag+fly ash binder improved compressive strength and decreased leaching amount of Cr ion.

• Journal of the Korean Chemical Society
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• 제20권4호
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• pp.277-279
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• 1976

A potentiometric titration method has been developed for the titration of copper with 2,5-dimercapo-1,3,4-thiadizole in aqueous solution using a silver electrode as an indicator electrode vs. the standard calomel electrode as a reference electrode. The 2,5-dimercapto-1,3,4-thiadiazole is very sensitive reagent for copper, which has been found to be highly selective for potentiometric determination of copper. Direct titration of trace amount of copper (0.02${\sim}$0.1 mg) is possible in the presence of a number of foreign ions in aqueous solution containing potassium hydrogen phthalate and sodium fluoride as masking agent under atmosphere.

• Journal of Hydrogen and New Energy
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• 제21권3호
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• pp.220-226
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• 2010

The heat transfer performance improvement in closed cooling water system of an electric power generation can be achieved by a corrosion control using corrosion inhibitors. The effect of trisodium phosphate and sodium nitrite upon carbon steel at various $Cl^{-1}$ ion containing water concentrations was examined by an integrated corrosion monitoring system. Nitrite was found to be the most effective inhibitor among tested inhibitors for carbon steel. The inhibiting process is considered as adsorption of nitrite ions in oxide layer which form a passive film on the carbon steel surface.

• Corrosion Science and Technology
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• 제9권6호
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• pp.265-269
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• 2010

This paper describes the exfoliation and surface modification of muscovite mica for UV coating formulation. For the exfoliation of the mica, hydrothermal process was used in the presence of lithium nitrate ($LiNO_3$). After the cation exchange with $Li^+$ ions, the surface of the mica was modified with several amphiphilic substances to increase compatibility and storage stability in UV coating formulation. Such a hydrophobic surface modification affected colloidal stability as well as dispersibility of the exfoliated mica in UV coating solution. Anticorrosive property of mica/UV coated steel plates was tested by salt spray test (SST) and compared with sodium montmorillonite ($Na^+$-MMT)/UV coated steel plates.

• Journal of the Korean Chemical Society
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• 제11권1호
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• pp.8-11
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• 1967

A method of determination of gold in ores has been established: Disolved ore solution is evaporated to dryness, redissolved with 0.1N HCl then chloroaurate formed is adsorbed on anion exchange resin, Dowex $1\;{\cdot}\;{\times}4$. The resin is ignited and the residue is dissolved with HCl-$HNO_3$. After evaporation of the acid, and then dilution with water, sodium azide is added. The gold is extracted with amyl alcohol from the solution buffered to pH 6. The gold is determined by measuring absorbancy of the alcohol layer spectrophotometricaly at $385m{\mu}$. Various factors, HCl concentration, amount of the resin rate, if adsorption, foreign ions, effecting to the method, have been examined. This method seems to be satisfactory for the determination of gold presented dawn to 1g per metric ton in ore.

• Bulletin of the Korean Chemical Society
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• 제24권5호
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• pp.555-558
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• 2003

An enrichment/separation system for atomic absorption spectrometric determinations of Cu(Ⅱ), Fe(Ⅲ), Ni(Ⅱ) and Co(Ⅱ) has been established. The procedure is based on the adsorption of the analytes as calmagite chelates on Chromosorb-102. The effects of some parameters including pH, amount of ligand, salt matrix, flow rates of sample and eluent solutions were investigated. Under optimized conditions, the relative standard deviation of the combined method of sample treatment, preconcentration and determination with FAAS (N=5) is generally lower than 5%. The limit of detection (3σ) was between 6.0-112.9 ㎍/L. The results were used for preconcentration of analytes from some sodium and ammonium salt.

• Journal of Life Science
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• 제10권1호
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• pp.94-100
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• 2000

Urease is an important microbial enzyme and its production is a marker to predict potential pathogenicity. An unusual halophilic bacterium producing urease was isolated from sea product and identified as Vibrio parahaemolyticus KH410. Its biochemical properties were indole negative, gelatin positive, sodium citrate positive and Kanagawa positive whereas other characteristics were identical as the standard strain except it showed a positive reaction on Christensen's urea agar. V. parahaemolyticus urease production was directly related to urea concentration. The production of urease was noticeable by the addition of 0.2% urea, 0.5% glucose, 2% NaCl in LB broth, and the initial pH of 5.5. The maximum production reached after 6 hr of incubation at 37$^{\circ}C$. However, NiCl2, metal ions, phosphorus did not affect production of urease.

• Proceedings of the Korean Fiber Society Conference
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• 한국섬유공학회 1996년도 추계 학술발표회
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• pp.53-58
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• 1996

The Chitin Thiocarbonate-Fe(II)-H2O2 redox initiator system was investigated for the graft copolymerization of acrylonitrile(AN) and acrylic acid(AA) monomers onto chitin powder. The reactions with vinyl monomers onto chitin were carried out under various the graft copolymerization conditions to elucidate the polymerization behavior in terms of graft yield. Reactions of chitin-acrylonitrile graft copolymer with hydroxyl amine hydrochloride and those with sodium hydroxide were conducted in order to obtain chitin-(amidoxime-co-acrylonitrile) and chitin-(acrylate-co-acrylamide) graft copolymers, respectively. The reaction efficiency was observed to depend on the alkali concentration, time, temperature, and the reactant concentrations. The prepared chitin derivatives were evaluated to find potential applications for use in wastewater treatments for adsorption and desorption of heavy metal ions as well as acidic and basic dyes.

• Journal of the Korean Ceramic Society
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• 제47권5호
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• pp.412-418
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• 2010

This paper presents the results of experimental work on both mechanical properties and durability of concrete or mortar incorporating silica fume. The aim of this study was to investigate the effect of replacement of silica fume on the performance of hardened concrete or mortar. The replacement levels of silica fume that replaced cement in this work were 0%, 5%, 10% and 15%, respectively. The results of this study indicate that both mechanical properties and durability of concrete are greatly dependent on the replacement levels of silica fume. As the replacement level of silica fume increased, the mechanical properties including compressive and flexural strengths, and static modulus of elasticity were proportionally enhanced. Furthermore, it was found that silica fume had some beneficial effects on the resistances to both chloride ions penetration and sodium sulfate attack. However, it exhibited poor resistances to both freezing-thawing action and magnesium sulfate attack.