• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.48.2-48.2
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• 2013

We present the near-infrared spectra (2.5-5.0 um) of shocked $H_2$ gas, observed with the Infrared Camera onboard the satellite AKARI. Two supernova remnants, IC 443 and HB 21, were observed. IC 443 shows a hint of non-equilibrium ortho-to-para ratio (OPR): 2.4 (-0.2, +0.3). HB 21 also shows an indication of a potential non-equilibrium OPR: 1.8-2.0. These non-equilibrium OPRs are first reported for shocked $H_2$ gas at E(v,J) > 7000 K, as far as we are aware. We concluded that the non-equilibrium OPR probably originates from dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that $H_2$ gas can form on grains with a non-equilibrium OPR. The difference in the collision energy of H atoms on grain surfaces would give rise to the observed difference between the OPRs of IC 443 and HB 21, if dissociative J-shocks are responsible for the $H_2$ emission. Our study suggests that shocked-then-cooled $H_2$ gas may play as a heat reservoir with the non-equilibrium OPR.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.53.1-53.1
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• 2008

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.52.2-52.2
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• 2008

• Carbon letters
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• v.10 no.1
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• pp.33-37
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• 2009

Activated carbon (AC) is one of the most effective adsorbents for organic compounds because of their extended surface area, high adsorption capacity, microporous structure and special surface reactivity. The composites of pH-sensitive hydrogel and activated carbon were prepared in order to improve the loading capacity of drug. The pH-sensitive hydrogel matrix swelled well in the basic condition to release the drug loaded in AC. The release of drug was controlled depending on both the pH due to the ionization of the carboxylic acid group and the AC due to the surface properties.

• Journal of Microbiology and Biotechnology
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• v.23 no.5
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• pp.731-737
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• 2013

Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.265-269
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• 2007

The effects of experimental variables for the electrochemical reduction of carbon dioxide by Carbon Monoxide Dehydrogenase (CODH) were investigated. It shows the pH optimum at 6.3 where the feasibility of electro-chemical reduction and the stability of CODH compromise each other. The optimum temperature for the reduction was at $60^{\circ}C$ where the enzyme shows the optimum activity although the solubility of carbon dioxide decreases as increasing temperature.

• Environmental Analysis Health and Toxicology
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• v.8 no.1_2
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• pp.11-17
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• 1993

Radioactive elements Li/sup +/, Rb/sup +/and Cs/sup +/ effect the period shortening in proportion to the higher concentration on the growth of Neurospora crassa. 1 mM LiCl presented the result of the period length 0.52 h shorter than average circadian rhythm 21.66 h. 1 mM RbCl reduced the period length 1.13 h than control period 21.89 h and 1 mM CsCl reduced 2.12 h than control period 21.89 h. In the equal concentration Cs/sup +/ had an extreme effect. Fatal doses of Li/sup +/, Rb/sup +/ and Cs/sup +/ are 20mM, 30mM and 20mM. In the fatal concentration Neurospora didn't develop more after 7 days and the formation of spores were not given in regular order. Circadian length of Neurospora decreased generally at the last cycle of the growth.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.563-566
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• 2000

In order to obtain microbial endochitosanase for enzymatic production of chitooligosaccharides from chitosan, we screened four microbes from soil and selected. Bacillus sp. HSB-21 which showed highest activity. Chitosanase, produced from isolating microbe, was endo-type and molecular mass of the enzyme was estimated as 21,000 by active staining. Its optimum pH and temperature were 5.5 and $50^{\circ}C$, respectively. It was stable in the pH range of 3.0 to 8.0 and up to $40^{\circ}C$. It did not produce chitomonosaccharide and produced chitooligosaccharide ranging from chitobiose to chitooctaose as major end-products from chitosan. The chitosanase from Bacillus sp. HSB-21 can be applicable to enzymatic production of chitooligosaccharide which has high degree of polymerization .

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.853-858
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• 2003

The reaction mechanism of the pyrolysis of sulphonyl oximes ($CH_3-C_6H_4-S(O)_2O-N=C(H)-C_6H_4Y$), in the gas phase is studied theoretically at HF/3-21G, ONIOM (B3LYP/6-31G**:HF/3-21G) and ONIOM (MP2/6- 31G**:HF/3-21G) levels. All the calculations show that the thermal decomposition of sulphonyl oximes is a concerted asynchronous process via a six-membered cyclic transition state. The activation energies (Ea) predicted by ONIOM (B3LYP/6-31G**: HF/3-21G) method are in good agreement with the experimental results for a series of tosyl arenecarboxaldoximes. Five para substituents, Y = $OCH_3$, $CH_3$, H, Cl, and $NO_2$, are employed to investigate the substituent effect on the elimination reaction. Linear Hammett correlations are obtained in all calculations in contrast to the experimental finding.

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1955-1958
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• 2004