• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.5
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• pp.86-94
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• 1999

Alkaline peroxide bleaching of chemi-mechanical pulp is a very complicated system where various process factors affect the bleacing performance and pulp properties. Traditional onefactor-at a time method is ineffective and costly infinding the optimal bleaching conditions. In this study, statistical experimental design and multiple regression method wre used to investigated the interactions among various bleaching factors and to find out the possbile maximal brightness development during one stage alkaline peroxide bleacing of TMP. The TMP was made from 10% Korean red pine and 90% Korean spruce and had an initial brightness of 54.5% ISO. the TMP was pretreated with EDTA(0.5% on O.D. pulp, 3% pulp consistency, 30$^{\circ}C$ for 60 minutes) and bleached in a 2 L Mark V Quantum Reactor at 750 rmp, 7.5% of bleaching consistency and with 0.05% magnesium sulfate addition. The ranges of chemical factors studied , based on oven-ried pulp, were 1-5% for hydrogen peroxide, 1-4% for sodium hydroxide and 1-4% for sodium silicate. The rages of reaction temperature and time were 50-90$^{\circ}C$ and 40-180minutes respectively. Interactions of hydrogen peroxide with alkali , time with temperature ature, alkali with time and silicate with temperature were found to be significant which means that hydrogen peroxide bleaching will be favored at stable concentration of perhydroxyl ion, relatively short time and low temperature, and high level of silicate. Mathematical model which has good predictability for target brightness in one stage peroxide bleaching can also be established easily. Base ion the model, maximal brightness of 70% ISO was found to at 50$^{\circ}C$ and 50 minutes by chemical additions of 5% for hydrogen peroxide, 3.2-3.4% for sodium hydroxide and 4% for silicate based on O.D. pulp. However, this result might not be suitable for situation where furnishes are different from ours, or different pretreatment is used, or bleaching carried out at different pulp consistency. In these cases it will be good to re-investigate the process by a similar methodology as was used in this study.

• Microbiology and Biotechnology Letters
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• v.5 no.3
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• pp.141-151
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• 1977

Distribution of tellurite and tellurate-reducing enzymes in the cell of Nocardia sp, the purifcation and the chemical properties of enzymes were investigated. Tellurite- and tellurate-reducing enzymes were located in the cytoplasm, but T. T. C. reduction part was in the cell membrane. Purification of tellurite- and tellurate-reducing enzymes was possible with the application of ammonium sulfate precipitation method and DEAE-Cellulose or CM-Cellulose column chromatographic method from the crude soluble part of the cell. On investigating the properties of purified enzyme, one of NADP, NADPH and reductive methylene blue(leucomethylene blue) was thought to react as a hydrogen donor. Both NADH and NADPH, or either of them would be physiological hydrogen donor.) In the reaction of this enzyme, either tellurite or tellurate reacts as a hydrogen acceptor, but on the other hand either selenate or selenate also reacts as a hydrogen acceptor.

• 한국해양학회지
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• v.28 no.3
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• pp.229-240
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• 1993

This study investigated the behaviour of sulfur species after the early diegenetic reduction of sulfate from pore solution in an anoxic intertidal flat deposit in the Banweol area of Kyeong-gi Bay, west coast of Korea. A total of seven sediment cores were collected during 1990∼1992 and were analyzed for their solid-phase sulfur species (acid-volatile sulfur, element sulfur, pyrite sulfur) as well as for chemical components in the pore solution, such as sulfate, ammonium, hydrogen sulfide, phosphate and Fe ion. The pore water sulfate oncentration was found to decrease rapidly downward from the sediment surface, while that of hydrogen sulfide, ammonium and phosphate showed and increase. The dissolved iron concentration in pore water, on the other hand, was found high in the surface layer of sediment, but fell sharply below this layer. these characteristic profiles of pore water sulfide and iron concentrations suggest that some reaction occurs between dissolved iron and sulfide ions, leading to the formation of various sulfide minerals in the sedimentary phase. The amount of inorganic sulfur species in the sediment increased downward, and showed a maximum of up to 7.9 mg/g. among the three species analyzed, acid-volatile sulfur (AVS) was dominant comprising more than 50% of the total. The amount of pyrite sulfur was greater than that of element sulfur. This implies that the formation of pyrite was restricted in this environment. the limited amount of element sulfur in this deposit may have discouraged the active formation of pyrite.

• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.142-146
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• 1975

The formation of iron oxide hydroxide in a ferrous sulfate was studied in different contents of iron in the solution at a temperature range of 90 to $100^{\circ}C$ under 1${\sim}$3 atmospheres. The Mohr's salt thus formed was hydrolyzed under 1 to 3 atmospheres, in 14 to 72 g/l of iron content in the solution pH 3 or 6 for two hours at 90 to $100^{\circ}C$. The results obtained was as follows; 1) In Mohr's salt solution, as the iron content was increased, with decreasing the concentration of hydrogen ion, the yield of iron oxide hydroxide was gradually increased. 2) When iron content in Mohr's salt solution was 42.81 g/l, 91.5% of iron was recovered in the form of $\alpha$-goethite similar to yellow grade of natural goethite. 3) When $\alpha$-goethite obtained was calcined of $500^{\circ}C$, it was turned into ${\alpha}$-ferric oxide with a redish brown colour.

• Journal of Marine Life Science
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• v.2 no.2
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• pp.49-55
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• 2017

Four chemical treatments with hydrogen peroxide (H₂O₂), copper sulfate (CuSO₄), potassium permanganate (KMnO₄) and chlorine (Cl₂) were applied to the effluent pond water of a hybrid striped bass saltwater recirculating aquaculture system to compare their oxidation power. Four chemicals were applied at concentrations of 0 (control), 1, 5, 10 and 20 mg/l. An additional concentration of 40 mg/l was included in the chlorine treatment. Water samples from four hybrid striped bass ponds were tested with KMnO₄ and Cl₂. H₂O₂ did not reduce any of BOD, COD and chlorophyll-a, and copper sulfate was only effective on chlorophyll-a for the effluent pond. Removal efficiencies for chlorophyll-a by copper sulfate were 19.2%, 37.5%, 54.2% and 74.1% dose-dependently. Potassium permanganate effectively removed the BOD, COD and chlorophyll-a. The COD removal rates in four fish ponds varied from 15.9% to 31.6% at the concentration of 10 mg/l. Interestingly, Cl₂ did not reduce the BOD and COD at all, but the BOD and COD instead increased drastically with increasing the Cl₂ concentration. The pond water with the highest initial BOD and COD values among the fish ponds tested increased by 350% in the BOD and 150% in the COD at 20 mg/l. Furthermore, Cl₂ did not significantly reduce any types of solid matter in this study, while KMnO₄ seemed to reduce some extent volatile dissolved solid in the fish pond.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.7
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• pp.1125-1132
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• 2013

In the kimchi manufacturing process, the starter is cultured on a large-scale and needs to be supplied at a low price to kimchi factories. However, current high costs associated with the culture of lactic acid bacteria for the starter, have led to rising kimchi prices. To solve this problem, the development of a new medium for culturing lactic acid bacteria was studied. The base materials of a this novel medium consisted of Chinese cabbage extract, a carbon source, a nitrogen source, and inorganic salts. The optimal composition of this medium was determined to be 30% Chinese cabbage extract, 2% maltose, 0.25% yeast extract, and $2{\times}$ salt stock (2% sodium acetate trihydrate, 0.8% disodium hydrogen phosphate, 0.8% sodium citrate, 0.8% ammonium sulfate, 0.04% magnesium sulfate, 0.02% manganese sulfate). The newly developed medium was named MFL (medium for lactic acid bacteria). After culture for 24 hr at $30^{\circ}C$, the CFU/mL of Leuconostoc (Leuc.) citreum GR1 in MRS and MFL was $3.41{\times}10^9$ and $7.49{\times}10^9$, respectively. The number of cells in the MFL medium was 2.2 times higher than their number in the MRS media. In a scale-up process using this optimized medium, the fermentation conditions for Leuc. citreum GR1 were tested in a 2 L working volume using a 5 L jar fermentor at $30^{\circ}C$. At an impeller speed of 50 rpm (without pH control), the viable cell count was $8.60{\times}10^9$ CFU/mL. From studies on pH-stat control fermentation, the optimal pH and regulating agent was determined to be 6.8 and NaOH, respectively. At an impeller speed of 50 rpm with pH control, the viable cell count was $11.42{\times}10^9(1.14{\times}10^{10})$ CFU/mL after cultivation for 20 hr - a value was 3.34 times higher than that obtained using the MRS media in biomass production. This MFL media is expected to have economic advantages for the cultivation of Leuc. citreum GR1 as a starter for kimchi production.

• Clean Technology
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• v.5 no.1
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• pp.20-29
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• 1999

In the treatment of Cu - and CN - contained wastewater by using Fenton oxidation-flocculation-precipitation, the optimal removal efficiencies of the cyanide and copper were investigated according to pH, reaction time, the molar ratio of cyanide and hydrogen peroxide and the mass ratio of ferrous sulfate and hydrogen peroxide for Fenton oxidation, and pH for hydroxide precipitation, respectively. As a result, the $CN^-$ removal efficiency in our experimental wastewater by the Fenton oxidation was 81.2%~99% at its optimal conditions of pH ranging from 3 to 5 and reaction time of 30 minutes. And the optimal dosage of hydrogen peroxide and ferrous sulfate was 214, $428mg/{\ell}$, 107, $161mg/{\ell}$, 214, $214mg/{\ell}$ and 520, $500mg/{\ell}$, respectively when the molar ratio of $Cu^{2+}$:CN is 2:1, 1:1, 1:2, 1:10, and was 900, $1050mg/{\ell}$ when the molar ratio of $Cu^+$: CN is 1:10. When the copper was precipitated by sodium hydroxide after Fenton oxidation, the copper removal efficiency in the wastewater at pH 7 was 98.92%, 98.52%, 92.46%, 90.6% and 95%, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.2
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• pp.124-131
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• 2008

Crude cytoplasmic fraction of phototrophic purple sulfur bacterium, Thiocapsa roseopersicina NCIB 8347, were initially prepared and purified by sonication, ultracentrifugation, ammonium sulfate fractionation and heat-treatment and it has been previously reported. Using various applications of chromatography far the purification of membrane-bound and soluble hydrogenases from heat-treated enzyme fraction were studied at present report. When the heat-treated enzyme preparation was applied to the anion column chromatography using Q-sepharose, Fraction I and II, which were extracted with the KCl 0-0.5 M gradient, showed the specific evolution hydrogenase activity 3.86 and 2.27 U/mg-protein respectively. Specific hydrogenase activitys of Fraction I and II were further increased to 4.35 and 7.46 U/mg-protein for Fraction I and to 2.49 and 4.41 U/mg-protein fur Fraction II respectively, when hydrophobic interaction column, Phenyl superose, and anion exchange column, Mono-Q, were applied. Size exclusion chromatography using superdex 200 concentrated the hydrogenase Fraction I and II to 9.19 and 7.84 U/mg-protein respectively at the final step of purification.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.6
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• pp.674-681
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• 2008

Silver as a metal catalyst has been used to remove odorous compounds. In this study, silver particles in nano sizes ($5{\sim}30nm$) were prepared on the surface of $NaHCO_3$, the supporting material, using a sputtering method. The silver nano-particles were dispersed by dissolving $Ag-NaHCO_3$ into water, and the dispersed silver nano-particles in the aqueous phase was applied to remove inorganic odor compounds, $NH_3$ and ${H_2}O$, in a scrubbing reactor. Since ammonia has high solubility, it was removed from the gas phase even by spraying water in the scrubber. However, the concentration of nitrate (${NO_3}^-$) ion increased only in the silver nano-particle solution, implying that the silver nano-particles oxidized ammonia. Hydrogen sulfide in the gas phase was rapidly removed by the silver nano-particles, and the concentration of sulfate (${SO_4}^{2-}$) ion increased with time due to the oxidation reaction by silver. As a result, the silver nano-particles in the aqueous solution can be successfully applied to remove odorous compounds without adding additional energy sources and producing any harmful byproducts.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.411-418
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• 2018

The polymer electrolyte membranes, CL-SPEEK/Cellulose composite membrane I, II, III with the improved electrochemical and mechanical properties were prepared and characterized. The engineering plastic polyether ether ketone (PEEK) and cellulose were sulfonated and cross-linked. The membranes were prepared by sol-gel casting method with different amount of cross-linking reagent. In conclusion, the composite membranes I, II, III showed improved thermostability, tensile strength and oxidative durability. Proton conductivity of the membranes was also improved and the composite membrane I showed 0.1312 S/cm at $80^{\circ}C$ which was the best of those composite membranes.