• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.285-291
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• 2016

There has been an accelerating increase in water reuse due to growing world population, rapid urbanization, and increasing scarcity of water resources. However, it is well recognized that water reuse practice is associated with many human health and ecological risks due to numerous chemicals and pathogenic microorganisms. Especially, the potential transmission of infectious disease by hundreds of pathogenic viruses in wastewater is one of the most serious human health risks associated with water reuse. In this study, we determined the response of different bacteriophages representing various bacteriophage groups to chlorination in real wastewater in order to identify a more reliable bacteriophage indicator system for chlorination in wastewater. Different bacteriophages were spiked into secondary effluents from wastewater plants from three different geographic areas, and then subjected to various doses of free chlorine and contact time at $5^{\circ}C$ in a bench-scale batch disinfection system. The inactivation of ${\phi}X174$ was relatively rapid and reached ~4 log10 with a CT value of 5 mg/L*min. On the other hand, the inactivation of bacteriophage PRD1 and MS2 were much slower than the one for ${\phi}X174$ and only ~1 log10 inactivation was achieved by a CT value of 10 mg/L*min. Overall, the results of this study suggest that bacteriophage both MS2 and PRD1 could be a reliable indicator for human pathogenic viruses for chlorination in wastewater treatment processes and water reuse practice.

• Applied Microscopy
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• v.43 no.4
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• pp.164-172
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• 2013

In this work, microstructural and hardness evolution of the X20 steel upon short-term creep test ($550^{\circ}C$ to $650^{\circ}C$, $180^{\circ}C$ to 60 MPa) was studied by using scanning electron microscope, electron backscattered diffraction, and transmission electron microscope, microhardness tester. After creep rupture, gauge and grip part of the specimens were microstructurally analyzed. Creep at the $650^{\circ}C$/60 MPa resulted in a rupture at 1,460 hours with growth of lath width from 1.31 to $2.87{\mu}m$ and a grain growth with a more equiaxed feature. There is a close relationship between Microhardness and lath width. The formation and coarsening of Laves phase, which was observed up to $600^{\circ}C$ of creep temperature, was accelerated by the applied stress. Slight coarsening of the $M_{23}C_6$ was observed in the $550^{\circ}C$ and $600^{\circ}C$ crept or aged specimens. The coarsening of $M_{23}C_6$ depended on the temperature, where specimens crept at $650^{\circ}C$ showed higher growth rate. The microstructural evolution of X20 after short-term creep test was extensively discussed in relation to the long-term creep/aging test reported in literatures.

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.1
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• pp.55-60
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• 2000

This experiment was carried out to determine the effect of cutting frequency(3rd and 5th cut) and level of nitrogen fertilization(l50 + liquid manure, 300 and 450kgha) on growth characteristics, dry matter yield and nutritive vaule of reed canarygrass(Pha1aris arundinacea L.), at the forage experimental field, College of Agriculture and Life Sciences, SNU, Suweon. Plant height of 3rd cutting(79.2cm) was significantly higher than that of 5th cutting(58.0cm). And dry mattter yield of cutting frequency was observed in 3rd cutting(16,902kgPna) and 5th cutting(l7,833kg/ha) As the nitrogen fertilization was increased, DM yield was significantly increased(p<0.05). When the nitrogen fertilization was applied at the level 150 + liquid manure, 300 and 450kg, dry matter yields were 16,5 12, 17,123 and 18,368kg/ha, respectively. The contents of neutral detergent fiber(NDF), acid detergent fiber(ADF) and in vitro dry matter digestibility(1VDMD) were similar among cutting frequency. However, slightly higher NDF, ADF and IVDMD contents were found in 5th cutting, but there was not affected by nitrigen fertilization. Based on the results of this experiment, it were indicated that to 5th cutting and 450kg nitrogen fertilization could be obtained from the increase of dry matter yield and nutritive value (Key words : Cutting frequency, Nitrogen fertilization, Dry matter yield, Nutritive Value, Reed canarygrass)

• Applied Microscopy
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• v.46 no.1
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• pp.37-44
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• 2016

In this study $TiO_2$/reduced graphene oxide ($TiO_2/rGO$) bipyramid with tunable nanostructure was fabricated by two-step solvothermal process and subsequent heat-treatment in air. The as-synthesized anatase $TiO_2$ nanocrystals possessed morphological bipyramid with exposed dominantly by (101) facets. Polyethylenimine was utilized during the combination of $TiO_2$ and graphene oxide (GO) to tune the surface charge, hindering the restack of graphene during solvothermal process and resulting in 1 to 5 layers of rGO wrapped on $TiO_2$ surface. After a further calcination, a portion of carbon quantum dots (CQDs) with a diameter about 2 nm were produced owing to the oxidizing and cutting of rGO on $TiO_2$. The as-prepared $TiO_2/rGO$ hybrid showed a highly photocatalytic activity, which is about 3.2 and 7.7 times enhancement for photodegradation of methyl orange with compared to pure $TiO_2$ and P25, respectively. We assume that the improvement of photocatalysis is attributed to the chemical bonding between rGO/CQDs and $TiO_2$ that accelerates photogenerated electron-hole pair separation, as well as enhances light harvest.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.3
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• pp.289-297
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• 2001

From March 1998 to February 1999, we observed visibility and weather change in Dae Chung Bong and Kwon Keum Sung three times a day; at 10 Am, 1 PM and 4 PM. During research period (357 days for Kwon Keum Sung, 351 days for Dae Chung Bong), clear days were 185 days(52%) in Kwon Keum Sung and 149 days (43%) in Dae Chung Bong. Months that had many clear days in a year were December and January in both area. The rate of clear day to cloudy day in Sokcho downtown and Dae Chung Bong was 5 to 5, 4 to 6, respectively. The number of cloudy day in a year in Dae Chung Bong was 34days more than in Sokcho downtown. The visual distance in Kwon Keum Sung was 12.2km on the clear day, and 3.3km on the cloudy day. The yearly average was 7.9km. And we can see 8.9km farther on the clear day. The visual distance in Dae Chung Bong was 13.3km on the clear day, and 3.1km on the cloudy day. The yearly average was 8.1km. The visibility of clear day was 10.2km longer than that of cloudy day. The percentage to observe East Sea clearly was about 70% between December and January in both areas, and showed the highest visibility during research period. We observed Mt. Keumkang from 3 to 6 times in a month except rainy season. The yearly average visibility was 2%. If you go Mt. Serok except April, when there was yellow duet cloud from China, and rainy season (between the last of June and early of September), you can appreciate the most beautiful Mt. Sorak with Mt. Keumkang.

• Korean Journal of Medicinal Crop Science
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• v.3 no.1
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• pp.71-76
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• 1995

Variation of plant characters and correlation anlaysis of its in Bupleurum falcatum, medicinal plant, were investigated to find useful selection characters and to obtain fundamental data for breeding. The variation was generally high. In plants having high height and many branch, stem thickness was high and leaf and root weight were great. The group of short height and many branch showing low frequency was higher than that of medium height and branch showing high frequency. And the correlation between top and root characters were positively significant The major top characters correlated with root yield were stem thick-ness, branch number, node number, node position attached 1st branch(NPFB), and leaf area.

• Environmental Analysis Health and Toxicology
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• v.21 no.3 s.54
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• pp.291-299
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• 2006

The experiments investigated whether early exposure to testosterone propionate (TP) during prepuberty alters testis development in Sprague-Dawley male rats. We performed Hershberger assay using the stimulated weanling male rats by OECD protocols, cDNA microarray, and Western blot. TP was subcutaneously injected to uncastrated Sprague-Dawley male rat of 22 days old for 10 consecutive days at doses of 0.4, 0.8, 1.0, 1.2, 1.6 mg/kg per day. At necropsy, the following tissues were removed and weighed: combined testes, epididymides (Epi), Cowper's glands (COW), levator am, and bulbocavernosus muscles (LABC), seminal vesicles, together with coagulating gland (SV) and ventral prostate (VP). We found that TP increased the weights of Epi, VP, SV, COW, and LABC, while testis was decreased in a dose-dependent manner. In cDNA microarray analysis of testis, there were significant reductions in the expression of cytochrome P450 11A (CYP11A), the rate-limiting enzyme of steroidogenesis. Taken together these results, TP exposure before puberty in male rats may produce the delay in testis development by inhibiting the CYP11A gene expression.

• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.87-105
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• 1991

The purpose of this experiment was to measure the leaking and solubility of commonly used dental restorative materials - Silux plus (CS), Hi-pol (CH), Clearfil F-II, Fissureseal (FS), Glass-Ionomer cement Fuji Type II (GI), Amalgam Cavex 68 (AM), Zinc Phosphate Cement (ZP) and gutta-percha (GP) and investigate the relation between the solubility and marginal leakage. Disc-shape specimens were fabricated with each material and dipped into deionized water, 0.01M lactic acid and 0.005M KOH solution, thus the total ionic concentrations in each solution was measured with ion chromatograph after 1, 3, and 7 days, respectively. For the solubility test, each specimen was immersed in 0.001M and 0.01M lactic acid for 24 hours, respectively and total weight loss was calculated. Also, Zn leaking through the margin of restorations was measured. The obtained results were as follows: 1. The amounts of eluted ion from the eight materials were most in 0.01M lactic acid and least in deionized water. 2. Of the eight materials, the fluoride release was greatest for glass ionomer cement (GI) in 0.01 M lactic acid after 7 days. 3. In analysis of the divalent cation, Mg was eluted most for zinc phosphate cement (ZP) and Ca for Clearfil F-II (CF) in 0.01M lactic acid after 7 days. 4. In analysis of transition metals, Cu and Zn were detected only. 5. The solubility rate of eight materials was greater in 0.01M lactic acid than in 0.001M for 24 hours, for zinc phosphate cement (ZP) the rate was greatest (5.4%) in 0.001M lactic acid, and amalgam least (0.01%). 6. The Zn concentration of restorative material with Z.P.C base was greater in 0.01M lactic acid than in 0.001M lactic acid.

• Archives of Pharmacal Research
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• v.25 no.1
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• pp.11-24
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• 2002

The antitumor antibiotic (+)-CC-1065 can alkylate N3 of guanine in certain sequences. A previous high-field $^1H$ NMR study on the$(+)-CC-1065d[GCGCAATTG*CGC]_2$ adduct ($^*$ indicates the drug alkylation site) showed that drag modification on N3 of guanine results in protonation of the cross-strand cytosine [Park, H-J.; Hurley, L. H. J. Am. Chem. Soc.1997, 119,629]. In this contribution we describe a further analysis of the NMR data sets together with restrained molecular dynamics. This study provides not only a solution structure of the (+)-CC-1065(N3- guanine) DNA duplex adduct but also new insight into the molecular basis for the sequence- specific interaction between (+)-CC-1065 and N3-guanine in the DNA duplex. On the basis of NOESY data, we propose that the narrow minor groove at the 7T8T step and conformational kinks at the junctions of 16C17A and 18A19T are both related to DNA bending in the drugDNA adduct. Analysis of the one-dimensional $^1H$ NMR (in $H_2O$) data and rMD trajectories strongly suggests that hydrogen bonding linkages between the 8-OH group of the (+)-CC-1065 A-sub-unit and the 9G10C phosphate via a water molecule are present. All the phenomena observed here in the (+)-CC-1065(N3-guanine) adduct at 5'$-AATTG^*$are reminiscent of those obtained from the studies on the (+)-CC-1065(N3-adenine) adduct at $5'-AGTTA^*$, suggesting that (+)-CC-1065 takes advantage of the conformational flexibility of the 5'-TPu step to entrap the bent structure required for the covalent bonding reaction. This study reveals a common molecular basis for (+)-CC-1065 alkylation at both $5'-TTG^*$ and $5'-TTA^*$, which involves a trapping out of sequence-dependent DNA conformational flexibility as well as sequence-dependent general acid and general base catalysis by duplex DNA.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.10-13
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• 1962

Titanium in solution of EDTA (Ethylenediaminetetraacetic acid) yield well-defined, reversible polarographic waves. In this report, a polarographic method for rapid determination of titanium in the Korean ilmenite was proposed, This polarographic method is based on the measurement of polarogram in the supporting electrolyte of EDTA. As the pH is increased the wave become more irreversible the diffusion current are diminished, and the half wave potential become more negative. In spite of the complication arising from numerous titanium species, in 0.2 M of EDTA, pH 6.3, the titanium waves are reproducible and analytically useful. In this medium titanium ion give well-defined reduction wave, and the half wave potential were -0.61V vs S.C.E. at pH 6.3. At the same time, the wave had a linear relationship between the concentration of titanium ion and the wave height. The Korean ilmenites were analyzed by this method and satisfactory results were obtained.