• Ocean and Polar Research
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• v.30 no.3
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• pp.335-345
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• 2008

In order to study spatial variabilities and major controlling factors, we measured fugacity of $CO_2(fCO_2)$, temperature, salinity and nutrients in surface waters of the North Pacific($7^{\circ}30'{\sim}33^{\circ}15'N$, $123^{\circ}56'E{\sim}164^{\circ}24'W$) between September$\sim$October 2007. The North Pacific and the marginal sea were distinguished by $fCO_2$ distribution as well as unique characteristics of temperature and salinity. There was a distinct diurnal SST variation in the tropical North Pacific area, and surface $fCO_2$ coincidently showed diurnal variation. In the North Pacific area, surface $fCO_2$ was mainly controlled by temperature, while in the marginal sea area it was primarily dependent on alkalinity and dissolved inorganic carbon concentrations. Air-sea $CO_2$ flux showed a large spatial variation, with a range of $-6.10{\sim}5.06\;mmol\;m^{-2}day^{-1}$. The center of subtropical gyre of North Pacific acted as a source of $CO_2(3.09{\pm}0.95\;mmol\;m^{-2}day^{-1})$. Tropical western North Pacific (i.e. the 'warm pool' area and the subtropical western North Pacific) acted as weak sources of $CO_2$($1.07{\pm}1.20\;mmol\;m^{-2}day^{-1}$ and $0.50{\pm}0.53\;mmol\;m^{-2}day^{-1}$, respectively). In the marginal sea, however, the flux was estimated to be $-0.68{\pm}1.17\;mmol\;m^{-2}day^{-1}$, indicating that this area acted as a sink for $CO_2$.

• Ocean and Polar Research
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• v.36 no.4
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• pp.423-435
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• 2014

Verifying the similarity of environmental characteristics between an artificial impact site and a preserved or reference site is necessary to quantitatively and qualitatively evaluate the environmental impact of mining activity. Although an impact site (BIS station) and a preserved site (called KOMO station) that have been selected in the Korea manganese nodule contract area may share similar environmental characteristics, similarities in terms of the water column environment between both sites has not been investigated. In this study, we compared the chemical properties of the water columns and sinking particle fluxes between BIS and KOMO stations through two observations (August 2011 and September 2012). Additionally, we observed particle fluxes at the KOMO station for five years (July 2003~July 2008) to understand long-term natural variability. Vertical distributions of water column properties such as dissolved oxygen, inorganic nutrients (N, P, Si), total organic carbon below surface layer (within the depth range of 200 m) were not considerably different between the two sites. Especially, values of water column parameters in the abyssopelagic zone from 4000 m to bottom layer (~5000 m) were very similar between the BIS and KOMO sites. Sinking particle fluxes from the two sites also showed similar seasonality. However, natural variation of particle flux at the KOMO site varied from 3.5 to $129.9mg\;m^{-2}day^{-1}$, with a distinct temporal variation originating from ENSO events (almost forty times higher than a minimum value). These results could provide valuable information to more exactly evaluate the environmental impact of mining activity on water columns.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2321-2327
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• 2015

Three coagulants, alum sulfate(alum), poly aluminum chloride(PAC) and poly aluminum silicate chloride (PASC), were used to remove low to high turbidity and TOC in surface and ground blended water. Laboratory experiments and pilot plant experiments were carried out to evaluate the optimal coagulant and its dosage. To determine the optimized coagulant and its dosage, the turbidity, TOC and pH were measured. The experimental results showed the best removal performance using PASC. The optimal dosage of PASC between 3-20 NTU was found to be 15 mg/L in the jar test. In the pilot test, a 15 mg/L PASC dosage was applied and resulted in the efficient removal of turbidity and TOC between 3.6-27 NTU. The removal efficiency of PASC increased with increasing turbidity and TOC.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1253-1261
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• 2000

Natural organic matter (NOM) which occurs ubiquitously in both surface and ground waters, consists of both humic (i.e., humic and fulvic acids) and nonhumic components. NOM in general as well as certain constituents are problematic in water treatment. From a regulatory perspective, concerns focus upon the role of NOM constituents as disinfection byproduct (DBP) precursors. The fractionation of NOM through water treatment processes can provide insight into treatment process selection and applicability. Problematic NOM fractions can be targeted for removal or transformation. Significant source-related differences in NOM were observed among various source waters. This study found that bulk Dissolved Organic Carbon (DOC) concentration was hardly removed by oxidation process. Oxidation transformed high Molecular Weight (MW) hydrophobic fraction into low MW hydrophilic fraction. Ozone reduced s-pecific Ultraviolet Absorbance (SUVA) value more than chlorine. High MW hydrophobic fraction was effectively removed by coagulation process. About 50% of Trihalomethane Formation Potential (THMFP) was removed by coagulation process.

• Journal of environmental and Sanitary engineering
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• v.16 no.3
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• pp.96-103
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• 2001

This study was carried out to investigate the major factors for the removal of NOMs (Natural Organic Matters) by alum ferric chloride and blended coagulants that consisted of alum and ferric chloride. Investigated factors were pH, the dosage of coagulant, alkalinity, hardness and bloc strength. The particle size contained in the test water came from the Han River was also measured. DOC(Dissolved Organic Carbon) removal at pH 6 was two to three times higher than at pH 8.5. The blended coagulant showed 9 to 10 percent higher DOC removal efficiency and 2 to 4 percent higher turbidity under the same condition. Alkalinity consumption of alum, ferric chloride and blended coagulant was 81%, 90% and 86% of theoretical value, respectively. The limit concentration of alkalinity to avoid pin floe was 10 mg $CaCO_3/L$ when alum was used. Hardness had no apparent effect on coagulation. The residual turbidity and $UV_{254}$ showed a tendency of increasing with floc strength($sec^{-1}$) increase. The order of floe strength was the following; alum >blended coagulant > ferric chloride. The particle counter test showed 89 percent of the small particle size(SPS, $1~5{\;}{\mu}textrm{m}$) and 11 percent of the medium to large particle size(M.LPS, $5~125{\;}{\mu}textrm{m}$). At PH7.85, the particle removal efficiencies of SPS($1~5{\;}{\mu}textrm{m}$) and M.LPS($5~125{\;}{\mu}textrm{m}$) in the coagulation process were 81% and 95%, respectively.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.674-681
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• 2009

Characteristics of organic matters (OM) in wastewater and the removal efficiencies were investigated using the influent and the effluent samples collected from 21 wastewater treatment plants. The OM characteristics investigated included biodegradability, humic content, specific UV absorbance (SUVA), the distribution percentage of refractory OM (R-OM), and synchronous fluorescence spectra. The types of wastewater (sewage, livestock waste/night soils, industrial waste) were easily distinguished by comparing the synchronous fluorescence spectra of the influent wastewater. The prominent peak of protein-like fluorescence (PLF) was observed for livestock waste/night soils whereas sewage exhibited a unique fluorescence peak at a wavelength of 370 nm. Irrespective of the wastewater types, the distribution percentage of R-OM increased from the influent to the effluent. Livestock waste/night soils showed the highest removal efficiency among all the three types of wastewater. There was no statistical difference of the removal efficiency between a traditional activated sludge and biological advanced treatment processes. Removal efficiency based on dissolved organic carbon DOC presented good correlations with the distribution percentage of R-OM and fulvic-like fluorescence (FLF) of the influent. The prediction for DOC removal efficiency was improved by using multiple regression analyses based on some selected OM characteristics and mixed liquid suspended solid (MLSS).

• Journal of Soil and Groundwater Environment
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• v.18 no.2
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• pp.36-44
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• 2013

The objectives of this study were to identify the characteristics of shallow groundwater from the oil-contaminated site for a long period and to evaluate the applicability of biopile technology to treat the soil excavated from it. The eight monitoring wells were installed in the contaminated site and pH, Electrical Conductivity (EC), Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP), Temperature and the concentrations of major ions and pollutants were measured. The VOCs in soil gas were monitored during biopile operation and TPH concentration was analyzed at the termination of the experiment. The pH was 6.62 considered subacid and EC was 886.19 ${\mu}S/cm$. DO was measured to be 2.06 mg/L showing the similar characteristic of deep groundwater. ORP was 119.02 mV indicating oxidation state. The temperature of groundwater was measured to be $16.97^{\circ}C$. The piper diagram showed that groundwater was classified as Ca-$HCO_3$ type considered deep groundwater. The ground water concentration for TPH, Benzene, Toluene, Xylene of the first round was slightly higher than that of the second round. The concentration of carbon dioxide of soil gas was increased to 1.3% and the concentration of VOCs was completely eliminated after the 40 days. The TPH concentration showed 98% remediation efficiency after the 90 days biopile operation.

• Corrosion Science and Technology
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• v.12 no.6
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• pp.280-287
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• 2013

Flow accelerated corrosion(FAC) of the carbon steel piping in pressurized water reactors(PWRs) has been major issue in nuclear industry. Severe accident at Surry Unit 2 in 1986 initiated the worldwide interest in this area. Major parameters influencing FAC are material composition, microstructure, water chemistry, and hydrodynamics. Qualitative behaviors of FAC have been well understood but quantitative data about FAC have not been published for proprietary reason. In order to minimize the FAC in PWRs, the optimal method is to control water chemistry factors. Chemistry factors influencing FAC such as pH, corrosion potential, and hydrazine contents were reviewed in this paper. FAC rate decreased with pH up to 10 because magnetite solubility decreased with pH. Corrosion potential is generally controlled dissolved oxygen (DO) and hydrazine in secondary water. DO increased corrosion potential. FAC rate decreased with DO by stabilizing magnetite at low DO concentration or by formation of hematite at high DO concentration. Even though hydrazine is generally used to remove DO, hydrazine itself thermally decomposed to ammonia, nitrogen, and hydrogen raising pH. Hydrazine could react with iron and increased FAC rate. Effect of hydrazine on FAC is rather complex and should be careful in FAC analysis. FAC could be managed by adequate combination of pH, corrosion potential, and hydrazine.

• ALGAE
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• v.27 no.3
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• pp.215-224
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• 2012

Growth dynamics of the seagrass, Zostera marina were examined at the two stations (Myungju and Dagu) in Jindong Bay on the southern coast of Korea. Eelgrass leaf productivities, underwater irradiance, water temperature, dissolved inorganic nitrogen (DIN) in water column and sediments, and tissue carbon (C) and nitrogen (N) content were monitored monthly from March 2002 to January 2004. Underwater irradiance fluctuated highly without a clear seasonal trend, whereas water temperature showed a distinct seasonal trend at both study stations. Water column DIN concentrations were usually less than $5{\mu}M$ at both study sites. Sediment pore water $NH_4{^+}$ and $NO_3{^-}+NO_2{^-}$ concentrations were higher at the Myungju site than at the Dagu site. Eelgrass leaf productivity at both study sites exhibited a distinct seasonality, increasing during spring and decreasing during summer. Seasonal variation of eelgrass productivity was not consistent with seasonal patterns of underwater irradiance, or water temperature. Eelgrass tissue C and N content at both study sites also showed significant seasonal variations. Relationships between tissue C and N content and leaf productivities exhibited usually negative correlations at both study sites. These negative correlations implied that the growth of Z. marina at the study sites was probably limited by C and N supplies during the high growth periods.

• Biomedical Science Letters
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• v.12 no.3
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• pp.241-247
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• 2006

To evaluate an effect of pathological liver damage on the cyclohexane (CH) metabolism, rats were pretreated with 50% carbon tetrachloride $(CCl_4)$ dissolved in olive oil (0.1ml/100g body weight) 10 or 17 times intraperitoneally at intervals of every other day. To these liver damaged animals, CH (a single dose of 1.56g/kg body weight, i.p.) was administered at 48hr after the last injection of $CCl_4$. The CH metabolites; cyclohexanol (CH-ol), cyclohexane-l,2-diol (CH-l,2-diol) and cyclohexane-l,4-diol (CH-l,4-diol) and cyclohexanone (CH-one) were detected in the urine of CH treated rats. After CH treatment, the serum levels of CH-ol and CH-one were remarkably increased at 4 hr and then decreased at 8hr in normal group. Whereas in liver damaged rats, these CH metabolites were higher at 8hr than at 4hr. The excretion rate of CH metabolites trom serum into urine was more decreased in liver damaged animals than normal group, with the levels of excretion rate being lower in $CCl_4$ 17 times injected animals than 10 times injected ones. It was interesting that the urinary concentration of CH metabolites was generally more increased in liver damaged animals than normal ones, and the increasing rate was higher in $CCl_4$ 17 times injected rats than 10 times injected ones. Taken all together, it is assumed that reduced urinary excretion rate of CH metabolites in liver damaged rats might be resulted from deteriorated hepatic and renal blood flow, and an increased urinary excretion amount of CH metabolites in liver damaged rats might be caused by reduced expiration amount of the metabolites due to lung damage.