• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.1-8
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• 1998

The purpose of this study is to determine the distribution of the suspended matter caused by dredging at the northeastern part of Kwangyang Bay and to determine the effect of the single silt protector for it. According to the direction of the tidal current, six sampling stations were chosen from the dredging site to the southeast. At the high tide, the high concentration of the suspended matter was observed below the mid-depth near the dredging site. As the tidal currents were stronger. its concentrations below the mid-depth at the inner stations of the single silt protector were rapidly increased, but those of the outer stations did not show any significant change. The concentrations at the inner stations of the silt protector at that time were from 20~140mg/l and those of the outer stations, which was only about 30 m apart from the inner station, were from 20~30mg/l. It suggests that the large amount of suspended matter caused by dredging were moved to the inner stations near the silt protector at the ebb tide and that the silt protector is very effective for the suspended matter.

• BMB Reports
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• v.41 no.4
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• pp.305-309
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• 2008

Cobalt is an essential microelements in many biological processes involving enzymatic activity. We found that $Zn^{2+}$ and $Mg^{2+}$, which are in the active site of native calf intestine alkaline phosphatase (CIP), can be replaced by $Co^{2+}$ directly in solution. The effect of $Co^{2+}$ concentration on the substitution reaction was examined at ratios of [$Co^{2+}$]/[CIP] from 0:1 to 8:1. The quantity of $Zn^{2+}$ in CIP decreased progressively as the ratio was increased, but the amount of $Mg^{2+}$ changed in irrregular fashion. A series of active site models of the reaction mechanism of CIP are proposed. Low pH was found to promote the replacement of $Mg^{2+}$ by $Co^{2+}$. To understand how the substitution affects the enzyme, we also solved the secondary structure of CIP after reaction with $Co^{2+}$ in different conditions.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.609-616
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• 2005

A high ammonia nitrogen ($NH_3-N$) concentration has been recursively observed every winter season in Geum River, which hindered chemical treatment processes at a water treatment plant. A flushing discharge from Daecheong Dam was often considered to dilute $NH_3-N$, but information on the quantitative effect of flushing on the downstream water quality was limited. In this study, the impact of a short-term reservoir flushing on the downstream water quality was investigated through field experiments and unsteady water quality modeling. On November 22, 2003, the reservoir discharge was increased from $30m^3/sec$ to $200m^3/sec$ within 6 hours for the purpose of the experiment. The results showed that flushing flow tends to reduce downstream $NH_3-N$ concentrations considerably, but the effectiveness was limited by flushing amount and time. An unsteady river water quality model was applied to simulate the changes of nitrogen concentrations in response to reservoir flushing. The model showed very good performance in predicting the travel time of flushing flow and the effect of flushing discharge on the reduction of downstream $NH_3-N$ concentrations at Maepo and Geumnam site, but a significant discrepancy was observed at Gongju site.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.914-919
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• 2008

This present was carried out to evaluate the adaptability of stabilization method which was used industrial byproducts as the stabilization agency in the abandoned mine site. In order to investigate stabilization effect on As-contaminated soils treated by industrial by-products, batch tests and column tests were carried out with As-contaminated soils collected from farmland around the abandoned mine site. ZVI(zero valent iron) and SRS(steel refining slag) was shown a good treatment effect. After the column test, sequential extraction test and simple bioavailability extraction test(SBET) were carried out to analysis of the soil, and scanning electron micrograph(SEM) analysis was carried out to compare the morphology and structure of ZVI and SRS before and after reacting with arsenic in the soil. As a result, ZVI and SRS were shown 93%, 62% reduction of As concentration respectively by comparison with untreated soils. Therefore, if ZVI and SRS are used as treatment materials in As-contaminated soils, it is expected that the As leaching from soils is reduced effectively.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.133-138
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• 2008

Fire can affect microbial community structure of soil through altered environmental conditions, nutrient availability, and biotic source for microbial re-colonization. We examined the influence of fire on chemical properties and soil enzyme activities of soil for 10 months. We also characterized the soil microbial community structure through ester-linked fatty acid analysis(EL-FAME). For this study, we established five burned plots(1*1 m) and 5 unburned plots outside the margin of fire. Soil was sampled three soil cores in a each plots and composited for analysis at 1, 3, 5, 8, and 10 month after fire. The fire caused an increase in soil pH, exchangeable Ca, and Mg, organic matter, available $P_2O_5$ compared to unburned sites. The content of $NH_4-N$ in burned site was significantly higher than that of unburned site and this effect continued for 8 months after fire. There was no difference of $NO_3-N$ content in soil between burned and unburned site. Fire caused no change in acid phosphatase and arylsulfatase activities but $\beta$-glucosidase and alkaline phosphatase activities in burned site were increased compared to unburned site. Microbial biomass as estimated by total concentration of EL-FAMEs in burned sites was significantly higher than that of unburned sites at one month after fire. Burned site decreased the EL-FAMEs indicative of gram-positive bacteria and tended to increase the fatty acid associated with gram-negative bacteria at one and three months after fire. The sum of EL-FAME compound $18:2{\omega}6,9c$ and $18:1{\omega}9c$ as served fungal biomarkers was decreased in burned site compared to unburned site.

• Korean Journal of Microbiology
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• v.14 no.3
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• pp.135-145
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• 1976

Confluent AGMK cells were infected by large plaque SV40 virus. Levels of DNA polymeras $({\alpha}\;and\;{\beta})$ were measured in the cytoplasm and the cell nucleus. The activities of DNA $polymerase-{\alpha}$ which found in both the cell nucleus and the cytoplasm were increased approximately eight folds at 48 hours after infection of SV40 virus. Only insignificant but constant amounts of DNA $polymerase-{\beta}$ were found either in the nucleus of the SV40 infected cell or of the uninfected cell. The characteristics of the SV40 virus induced DNA polymerases were compared with that of the uninfected cellular DNA polymerase in regard of the effects of pH, salt concentration, NEM concentration and temperature on those enzyme activities. No differential effect was found between both enzymes. Endouclease activities wre examined in the purified DNA $polymerase-{\alpha}\;and\;{\beta}$. The low level of endonuclease activity which might cut SV40 DNA 1 at one site was observed in the DNA $polymerase-{\alpha}$ whereas high but nonspecific endonuclease activities were found in the DNA $polymerase-{\beta}$.

• Journal of Plant Biology
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• v.25 no.1
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• pp.21-36
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• 1982

The activity of photosystem II in isolated chloroplast form the leaves of Sedum sarmentosum was measured. The photoreduction rate of DCPIP by photosystem II showed the circadian rhythm with a peak at near midday sample for a continuing fine day and at near afternoon between nidday and sunset sample for a continuing cloudy day in summer. The optimum light intensity of photoreduction by photosystem II in the chloroplast preparation was about 5~9$\times$$10^4$ lux. The saturated light intensity was over 9$\times$$10^1$lux. Photosystem II activity was inhibited by even the lowest concentration of lead. When Pi and ATP of the same concentration as Pb were added to the reaction mixture containing Tris buffer lacking of Pi prior to Pb incubation, photosystem II activity was protected from Pb-inhibiting effect by the pretreament of Pi and ATP. It was assumed that Pb inhibiiton was probably due to one, P-depriving by the precipitates of $Pb_3$ $($Pb_4$)_2$ in the reaction mixture and the other, partially Pb-combing with Pi groups of the active site of photosystem II.

• Bulletin of the Korean Chemical Society
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• v.15 no.3
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• pp.198-204
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• 1994

Chemical shifts in aqueous sodium dodecylsulfate(SDS) micellar solution solublizing phenol, catechol, resorcinol, hydroquinone have been measured to investigate solubilization properties. Proton nuclear magnetic resonance frequencies of solubilizates as well as those of the ${\alpha}$-methylene, middle methylene and terminal methyl of SDS shift linearly as a function of solubilizate concentration. From the plots of observed chemical shift (v) vs solubilizate concentration, slope (a) and solubilizate free chemical shift ($v_0$) are obtained. They are very informative to solubilization site of the systems. Catechol and phenol solubilized SDS and catechol solubilized dodecylpyridinium chloride(DPC), dodecyltrimethylammonium bromide(DTAB) systems are studied using the same method to compare head group effect and middle methylene proton signal splitting. It is proposed that phenol and catechol are inserted into micellar interior and the number of methylenes assigned to the higher field peaks is 5.0${\pm}$0.5.

• Journal of Ecology and Environment
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• v.36 no.1
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• pp.31-38
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• 2013

Annual ring formation is considered a source of information to investigate the effects of environmental changes caused by temperature, air pollution, and acid rain on tree growth. A comparative investigation of annual ring growth of Cryptomeria japonica in relation to environmental changes was conducted at two sites in southern Korea (Haenam and Jangseong). Three wood disks from each site were collected from stems at breast height and annual ring growth was analyzed. Annual ring area at two sites increased over time (p > 0.05). Tree ring growth rate in Jangseong was higher than that in Haenam. Annual ring area increment in Jangseong was more strongly correlated with environmental variables than that in Haenam; annual ring growth increased with increasing temperature (p < 0.01) and a positive effect of $NO_2$ concentration on annual ring area (p < 0.05) could be attributed to nitrogen deposition in Jangseong. The correlation of annual ring growth increased with decreasing $SO_2$ and $CO_2$ concentrations (p < 0.01) in Jangseong. Variation in annual growth rings in Jangseong could be associated with temperature changes and N deposition. In Haenam, annual ring growth was correlated with $SO_2$ concentration (p < 0.01), and there was a negative relationship between precipitation pH and annual ring area (p < 0.01) which may reflect changes in nutrient cycles due to the acid rain. Therefore, the combined effects of increased $CO_2$, N deposition, and temperature on tree ring growth in Jangseong may be linked to soil acidification in this forest ecosystem. The interactions between air pollution ($SO_2$) and precipitation pH in Haenam may affect tree growth and may change nutrient cycles in this site. These results suggested that annual tree ring growth in Jangseong was more correlated with environmental variables than that in Haenam. However, the further growth of C. japonica forest at two sites is at risk from the long-term effects of acid deposition from fossil fuel combustion.

• Journal of Environmental Impact Assessment
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• v.5 no.2
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• pp.21-31
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• 1996

To assess the impact resulted from the slag dumping, we studied that the changes in the concentration of heavy metal were researched through the statistic analysis at 4 stations in Yongil bay, Korea from 1988 to 1995. And in order to clarify resulting from the changes in heavy metal concentration due to be leaked out from dumped slag, it was fulfilled experiments of the slag extraction. In the extracting experiment, Pb and As were only leaked out from slag aged during 10 days but all of heavy metals were not from it aged during 90 or 180 days. It was found that the concentrations of heavy metals in sea water of vincinity of slag dumping area were still remained in similar, comparing with it of control site(site 4) when they were by analysed statistic method, anova test and Mann-Whitney test. The slag recycling ratio of our country is lower than foreign country. While we need to apply a new process for phosphate treatment, foreign country already apply a slag to phosphorous removal. We suggest that slag dumping cannot putatively affected the changes in the concentration of heavy metal. And we thought that impact of heavy metal induced by slag dumping was not severe. So, it is necessary to utilize this process in phosphorous removal, like a foreign country.