• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.18-25
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• 2001

A new wood-degrading fungus Trichophyton rubrum LKY-7 secretes a high level of laccase in a glucose-peptone liquid medium. The production of laccase by the fungus was barely induced by 2,5-xylidine. The laccase has been purified to homogeneity through three chromatography steps in an overall yield of 40%. The molecular mass of the purified laccase was about 65 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified laccase had the distinct blue color and had basic spectroscopic features of a typical blue laccase: two absorption maxima at 278 and 610 nm and a shoulder at 338 nm. The N-terminus of the laccase has been sequenced, revealing high homology to laccases from wood-degrading white-rot fungi such as Ceriporiopsis subvermispora. The enzyme had a "low" redox potential (0.5 V vs normal hydrogen electrode), yet it was one of the most active laccases in oxidizing a series of representative substrates/mediators. Compared with other fungal laccases, the laccase has a very low Km value with ABTS [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid] as a substrate and a very high Km value with violuric acid as a substrate. The laccase has the isoelectric point of 4.0. The laccase had very acidic optimal pH values (pH 3-4) while it was more stable at neutral pH than at acidic pH. The laccase oxidized hydroquinone faster than catechol and pyrogallol. The oxidation of tyrosine by the laccase was not detectable under the reaction conditions. The laccase was strongly inhibited by sodium azide and sodium fluoride. fluoride.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.116-121
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• 2008

In my search of microbial source of novel enzymes, a marine actinomycetes, A1460, producing haloperoxidase was isolated from macroalgae from south sea, Korea and studied for physiological and biochemical properties. The haloperoxidation reaction was followed by the bromination of phenol red in the presence of hydrogen peroxide and potassium bromide. The haloperoxidase was partially purified from the cell extract with $35\sim75%$ ammonium sulfate precipitation, High-Q anion exchange chromatography, gel filtration chromatography, hydroxyapetite chromatography and hydrophobic interaction chromatography to a yield of 42% and purification fold of 70. This enzyme showed relatively high heat stability without losing 50% of activity after 1 hr incubation at $60^{\circ}C$. The highest activity was found at $45^{\circ}C$, and the optimal pH was about pH 7, but higher stability was observed at pH 8. Azide and cyanide ion showed strong inhibition at less than 1 $\mu M$ level suggesting that the enzyme was Fe ion dependent haloperoxidase.

• Journal of Pharmaceutical Investigation
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• v.26 no.3
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• pp.221-232
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• 1996

An abrasive, calcium hydrogen phosphate dihydrate (DCPD), was synthesized in a Box-wilson experimental design by reactions between phosphoric acid and milk of lime, and calcium chloride and sodium phosphate solutions, and stabilized with TSPP and TMP. The optimum conditions for preparation of DCPD from phosphoric acid with milk of lime were such as; reaction temp.; $51.9^{\circ}C$, conc. of lime; 25.9%, conc. of phosphoric acd; 77.9%, drying temp.; $60.2^{\circ}C$ and final pH; 6.46. The physico-chemical and pharmaceutical properties of DCPD were showed as follows: glycerin absorption value(68 ml/100g), whiteness(99.5%), particle size(10.9 nm), pH(7.8), and set test(pass). XRD and SEM of DCPD indicated a monoclinic system crystallographically. $N_2$ adsorption isotherm curve by BET showed non porous type II form. The micromeritic parameters of DCPD showed that surface area was $3.27{\sim}4.6\;cm^{2}/g$ and pore volume, pore area and pore radius were negligible. The rheogram of the toothpaste containing DCPD showed pseudoplastic flow with yield value of 321, and thixotropic behavior forming hysteresis loop. These results meet the requirements as abrasive standard, and sythesized DCPD is expected as a good dental abrasive such as a high quality grade in practice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.112-119
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• 2018

Heat stress during the ripening stage reduces the yield and quality of rice. Considering the adverse effects of global warming, it is necessary to breed heat stress tolerant rice cultivars and analyze their stress tolerance characteristics. We investigated the ripening characteristics and antioxidant enzyme activity of Ilmi under heat stress condition during the ripening stage. Ripening rate, 1000 brown grain weight, and rice quality of Ilmi were not significantly changed by heat stress during the ripening stage. Leaf chlorophyll, chlorophyll a/b ratio, and malondialdehyde (MDA) contents of Ilmi leaves were also less changed than those of Ilpum. These results strongly suggested that Ilmi has heat tolerance characteristics during the ripening stage. Analysis of antioxidant enzyme activity of Ilmi revealed that peroxidase (POX) activity was significantly higher than that of Ilpum, and showed a significant correlation with the change in chlorophyll a/b ratio and hydrogen peroxide content of flag leaves of Ilmi. These data suggest that the high POX enzyme activity of Ilmi could be considered one of its major heat tolerance characteristics.

• Korean Journal of Medicinal Crop Science
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• v.16 no.6
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• pp.439-445
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• 2008

This study was performed to investigate a methodology of improving immune activities of Berberis koreana Palibin by ultra high pressure on low temperature extraction process. Extraction yield was enhanced up to more than 35% by above process, compare to the control and extraction average. The cytotoxicity on human kidney cell (HEK293) was showed below 20.4%, 21.6% in adding 1.0 mg/ml of the highest concentration. Generally, the extracts by ultra high pressure extraction process showed less toxicity about 5% than the other processes. It could tell that toxic materials that existing in the plant could be reduced or broken by ultra high pressure process due to can be broken bond such the hydrogen bond, the electrostatic bond, the van der Waals bond, and the hydrophobic bond, can be broken by high pressure. The result could be employed to develop a new type of functional food from B. koreana Palibin by low temperature high pressure process.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.704-710
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• 2014

Biomass is considered an alternative energy which can solve an greenhouse gas problem like $CO_2$ which is a major contributor to global warming. The biomass can be converted to various energy sources through thermochemical conversion. In this study, a continuous gasifier was engineered for a wood biomass gasification. The biomass was used a waste wood. The experiments of $CO_2$ gasification were achieved as the gasification temperature, moisture content and input $CO_2$ concentration. The results showed that the yield of producer gas increased with an increasing the gasification temperature. The amount of the light tar increased due to the decomposition of gravimetric tar by the thermal cracking, and the char was confirmed pore development through the SEM analysis. The CO concentration was increased with an increased input $CO_2$ concentration from Boudouard reaction. Through the parametric screening studies, the hydrogen and carbon monoxide concentration were 32.91% and 48.33% at the optimal conditions of this test rig.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.981-987
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• 2011

The anomalous spectroscopic properties of quercetin-3-O-rhamnoside (QCRM) and quercetin-3-O-rutinoside (QCRT) in AOT reverse micelle were studied. The excited state intramolecular proton transfer (ESIPT) occurs through the strong hydrogen bond between the -OH at position 5 and the carbonyl oxygen. Because the ESIPT can only happens in the $S_1$ state and the Franck-Condon factor involved in the $S_2\;{\rightarrow}\;S_1$ internal conversion is small, the $S_2\;{\rightarrow}\;S_o$ emission alone appears. Because the molecular planarity is improved at the interior of the micelle, the excited state intramolecular charge transfer in the $S_1$ state is extended, and the excited state is more tolerable for any quenching effects in the micelle. Therefore, an $S_1\;{\rightarrow}\;S_o$ emission was newly discovered under this micelle microenvironment. For the $S_2\;{\rightarrow}\;S_o$ emission, the quantum yields increase but the quantum yield of the $S_1\;{\rightarrow}\;S_o$ emission approximately decreases as the water concentration in the micelle increases.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3617-3622
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• 2010

The reaction of stoichiometric amount of $FeCl_2{\cdot}4H_2O$, (2-pyridylmethyl, 3-pyridylmethyl)amine (2,3-pyma) and sodium azide/sodium thiocyanate in methanol under aerobic conditions affords the dinuclear Fe(III) complexes, [(2,3-pyma) $(N_3)_2Fe({\mu}-OCH_3)_2Fe(N_3)_2$(2,3-pyma)]${\cdot}CH_3OH$ (1) and [(2,3-pyma)$(NCS)_2Fe({\mu}-OCH_3)_2Fe(NCS)_2$(2,3-pyma)] (2) in good yield. Two bis-methoxy-bridged diiron(III) complexes are isolated and characterized. The coordination geometries around iron(III) ions in 1 and 2 are the same tetragonally distorted octahedron. The iron(III) ions are coordinated by two nitrogens of a 2,3-pyma, two nitrogens of two azide/thiocyanate ions, and two oxygens of two methoxy groups. Both compounds are isomorphous. The structures of 1 and 2 display the C-$H{\cdots}\pi$ and/or $\pi-\pi$ stacking interactions as well as hydrogen bonding interactions, respectively. Compounds 1 and 2 show significant antiferromagnetic couplings through the bridged methoxy groups between the iron(III) ions in the temperature range from 5 to 300 K ($H=-2JS_1{\cdot}S_2$, J=-19.1 and $-13.9\;cm^{-1}$ for 1 and 2).

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1958-1962
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• 2007

The title complex, Ir(H)(CO)(PEt3)2(η 2-C60) (2), has been prepared by the reaction of excess C60 (4 equiv) with a tetrairidium complex Ir4(CO)8(PEt3)4 (1) in refluxing chlorobenzene in 40% yield as green crystals. Compound 2 has been characterized by cyclic voltammetry (CV), spectroscopic methods (mass, IR, 1H and 31P NMR), and a single crystal X-ray diffraction study. The molecular structure reveals that the iridium atom of 2 is coordinated by two axial ligands of a hydrogen atom and a carbonyl group, and three equatorial ligands of two phosphorus atoms and an η 2-C60 moiety. The CV study exhibits three reversible one-electron redox waves for the successive reductions of 2, together with additional four redox waves due to free C60 reductions, which was formed by decomposition of 2 in the reduced states. The three reversible redox waves of 2 are shifted to more negative potentials by ca. 270 mV compared to free C60, reflecting both metal-to-C60 π-back-donation and the electron-donating nature of the two phosphorus ligands.

• Corrosion Science and Technology
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• v.5 no.5
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• pp.168-172
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• 2006

Alloy 600 having a superior resistance to a corrosion is used as a steam generator tubing in nuclear power plants. In spite of its high corrosion resistance, there are many tubings which experience corrosion problems such as a SCC under the high temperature and high pressure environments of nuclear power plants. The Alloy 600 tubing can be repaired by using a Ni electroplating having an excellent SCC resistance. In order to carry out a successful Ni electrodeposition inside a steam generator tubing, the effects of various parameters on the material properties of the electrodeposit should be elucidated. Hence this work deals with the effects of an applied current density, duty cycle($T_{on}/(T_{on}+T_{off})$) of a pulse current, bath temperature and solution pH on the material properties of Ni electrodeposit obtained from a Ni sulphamate bath by analyzing the current efficiency, potentiodynamic curve, hardness and stress-strain curve. Hardness, YS(yield strength) and TS(tensile strength) decreased whereas the elongation increased as the applied current density increased. This was thought to be by a concentration depletion at the interface of the electrodeposit/solution, and a fractional decrease of the hydrogen reduction reaction. As the duty cycle increased, the hardness, YS and TS decreased while the elongation increased. During an off time at a high duty cycle, the concentration depletion could not be recovered sufficiently enough to induce a coarse grain sized electrodeposit. With an increase of the solution temperature and pH, the YS and TS increased while the elongation decreased. The experimental results of the hardness and the stress-strain curves can be supplemented by the results of the potentiodynamic curve.