• 상하수도학회지
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• 제19권6호
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• pp.738-748
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• 2005

Considering pollution source is transferred by discharge, it is very important to analyze the correlation between discharge and water quality. And temperature also influent to the water quality. In this paper, it is used water quality data that was measured DO (Dissolved Oxygen), TOC (Total Organic Carbon), TN (Total Nitrogen), TP (Total Phosphorus) at Dalchun real time monitoring stations in Namhan river. These characteristics were analyzed with the water quality of rainy and nonrainy periods. Input data of the water quality forecasting models that they were constructed by neural network and neuro-fuzzy was chosen as the reasonable data, and water quality forecasting models were applied. LMNN (Levenberg-Marquardt Neural Network), MDNN (MoDular Neural Network), and ANFIS (Adaptive Neuro-Fuzzy Inference System) models have achieved the highest overall accuracy of TOC data. LMNN and MDNN model which are applied for DO, TN, TP forecasting shows better results than ANFIS. MDNN model shows the lowest estimation error when using daily time, which is qualitative data trained with quantitative data. If some data has periodical properties, it seems effective using qualitative data to forecast.

• 한국수산과학회지
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• 제36권5호
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• pp.458-462
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• 2003

This study was to survey proper condition of nitrate removal by hydraulic retention time (HRT) and measured growth of black rockfish (Sebastes schlegeli) and giant croaker (Nibea japonica) in the seawater recirculating culture system designed for nitrate removal. Nitrate conversion to nitrogen at 8 hr-HRT was higher than 16 hr-HRT, amounting to $32.2\;g/m^3/day$ in the seawater recirculating culture system. The removal efficiency of nitrate improved when dissolved oxygen was situated less than 0.5 mg/L. Daily growth rate (DGR) and feed efficiency (FE) of S. schlegeli with mean body weight of 108 g in 8 hr-HRT were significantly higher values than those in 4 hr-HRT (P<0.05). The DGR and FE of N. japonica with mean body weight of 12 g in added carbon system showed not differing in the values from N. japonica in control system (P>0.05).

• 한국해양환경ㆍ에너지학회지
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• 제4권3호
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• pp.16-27
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• 2001

시화호 퇴적물에서 인의 지화학적 특성을 연구하였다 퇴적인의 가장 큰 형태는 detrital apatite P와 Al-bound P이며 무산소환경이기 때문에 Fe-bound f는 그 비중이 낮았다. 퇴적총인과 유기물의 상관성으로 볼 때, 퇴적물로 제거되는 인의 거동은 유기물에 의해 조절되는 것으로 나타났다. 또한, 유기물 유입의 영향을 직접적으로 받는 정점 Cl에서 정점 C2에 비해 퇴적인의 함량, 유기물과의 상관성, 황산염환원에 의한 공극수내 인산염의 함량 및 플럭스가 높게 나타났다. 결국 시화호 퇴적물에서 인의 함량, 형태 및 공간에 따른 차이는 유기물에 의해 조절되는 것으로 밝혀졌다.

• Ocean Science Journal
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• 제42권3호
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• pp.165-170
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• 2007

The structure of the nematodes communities has been studied in the sediments on two sites located outside and under the layer of Ahnfeltia tobuchiensis (Kanno and Matsubara 1932; Makijenko 1970). Bottom sediments at the stations were represented by sands with a different degree of silting. Specific structure of nematodes at the stations was significantly different under the similar environmental conditions (water depth, dissolved oxygen saturation, salinity, temperature of the bottom layer and organic carbon content inside of the sediment). Nematodes dominated (75.7 %) in meiobenthos community under the layer of A. tobuchiensis where concentration of silt particles was 12 %. Representatives of the family Comesomatidae were dominant. Low index of species diversity and high Simpson domination index were detected in this community. Under a layer of A. tobuchiensis with the thickness of 30 cm concentration of the silt particles was 5.39 %; nematodes density was low and made 32.1 % of the general density of meiobenthos. Species of the families Xyalidae and Monoposthiidae were dominant. Outside of A. tobuchiensis, field percentage of silt particles was minimal (3.1 %) and representatives of families Cyatholaimidae and Axonolaimidae dominated. The specific structure of nematodes in this type of the ground is characterized by high index of species diversity and low level of domination.

• 상하수도학회지
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• 제30권1호
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• pp.69-75
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• 2016

This study was conducted to examine the byproducts formation characteristics at the water treatment plants which applying electrolysis as a disinfection process in Gangwondo, Korea. Total of forty plants located in Gangwon Province, Korea were selected for the study. Correlation between dissolved organic carbon(DOC) and $SUVA_{254}$ was not clear. Among the species of the disinfection byproducts(DBPs), chlorate and trihalomethanes(THMs) accounted for 76% and 14% of DBPs, respectively. The effect of DOC or $SUVA_{254}$ on DBPs formation was not clearly demonstrated. The increased amount of THMs due to the raw water bromide content was found primarily in the form of chloroform, and the percent fraction of BDCM(bromodichloromethane) and DBCM(Dibromochloromethnae) was relatively insignificant. When the value of $SUVA_{254}$ was greater than $2L/mg{\cdot}m$, the percent fraction of BDCM and DBCM decreased while percent fraction of CF(chloroform) increased.

• 상하수도학회지
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• 제25권4호
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• pp.597-604
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• 2011

This study was performed to compare finished water quality among three different processes. A detailed assessment of performance was carried out during the five months of operation. Finished water quality was evaluated on the basis of parameters such as Dissolved organic carbon (DOC), $UV_{254}$ absorbance, haloacetic acid formation potential (HAAFP), geosmin, 2-methylisoborneol (2-MIB), heterotrophic bacteria and total coliform bacteria. The treatment processes were Process 1 (coagulation-flocculation-sedimentation-sand filtration-ozone-GAC), Process 2 (coagulation-flocculation-sedimentation -microfiltration-ozone-GAC), and Process 3 (coagulation-flocculation-sedimentation- sand filtration-GAC), compared side by side in the pilot testing. Process 2 was found to have better removal efficiency of DOC, $UV_{254}$ absorbance, HAAFP and heterotrophic bacteria in comparison with process 1 and process 3 under identical conditions. Geosmin, 2-MIB and total coliform bacteria were not detected in finished water from each process.

• 한국막학회:학술대회논문집
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• 한국막학회 1996년도 제4회 하계분리막 Workshop (초순수 제조와 막분리 공정)
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• pp.121-147
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• 1996

Since 1980, the water quality of ultra-pure water has been rapidly improved, and presently ultra-pore water producing equipment for 64Mbit is in operation. Table 1 shows the degree of integration of DRM and required water quality exlmple. The requirements of the ultra-pure water for 64Mbit are resistivity: 18.2 MQ/cm or higher, number of particulates: 1 pc/ml or less (0.05 $\mu$m or larger). bacteria count: 0.1 pc/l or less. TOC (Total Organic Carbon, index of organic snbstance) : 1ppb or less, dissolved oxygen: 5ppb or less, silica: 0.5ppb or less, heavy metal ions: 5ppb or less. The effect of metals on the silicon wafer has been well known, and recently it has been reported that the existence of organic substance in ultra-pure water is closely related to the device defect, drawing attention. It is reported that if organic substance sticks to the natural oxidation film, the oxide film remaims on the organic substance attachment in the hydrofluoric acid treatment (removal of natural oxidation film). The organic substance forms film on the silicon wafer, and harmful elements such as metals and N.P.S., components contained in the organic substance and the bad effect due to the generatinn of silicon carbide cannot be forgotten. In order to remove various impurities in raw water, many technological develoments (membrane, ion exchange, TOC removal, piping material, microanalysis, etc.) have been made with ultra-pure water producing equipment and put to practical use. In this paper, technologies put to practical use in recent ultra-pure vater producing equimeut are introduced.

• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.443-451
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• 2001

In order to investigate what kind of response anaerobic bifidobacteria has on oxygen stress, five oxygen-tolerant bifidobacteria were isolated from human fecal samples. All were temporarily identified as Bifidobacterium longum through an analysis of carbohydrate utilization patterns and cellular fatty acid profiles. In the presence of oxygen, the lag phase became extended and the cell growth was suppressed. Bifidobacterial cell was able to remove dissolved oxygen in an early stage of growth and to overcome oxygen stress to a certain extent. The cell became long n size and showed a rough surface containing many nodes which were derived from abnormal or incomplete cell division. Cellular fatty acid profiled changed remarkably under a partially aerobic condition, so that the carbon chain of cellular fatty acid became short. All the dimethyl acetals originated from plasmalogen were reduced, any cyclopropane fatty acid, 9, 10-methyleneoctadecanoic acid ($C_{19:0}cyc9,10$), was increased remarkably. Oxygen stress induced a 5.5 kD protein in B. longum JI 1 of the oxygen-teolerant bifidobacteria, that was named Osp protein, and its N-terminal amino acid sequence was as follows: unknown amino acid-Thr-Gly-Val-Arg-Phe-Ser-Asp-Asp-Glu. Therefore, the oxygen-tolerant bifidobacteria seemed to defend against oxygen stress byincreasing the content of short fatty acid and cyclopropane fatty acid, and induction of an oxygen stress protein, but not the plasmalogen.

• 상하수도학회지
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• 제18권2호
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• pp.121-127
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• 2004

It is necessary to supply external carbon source for enhancement of biological nitrogen removal from domestic wastewater with low influent C/N ratio. Sulfide was chosen as a cost effective electron donor and reaction stoichiometry for autotrophic denitrification was investigated by conducting bench-scale experiments in this study. Higher sulfur to nitrogen (S/N) ratio than the calculated value from theoretical reaction stoichiometry was required when the anoxic reactor was operated at open condition because dissolved oxygen introduced by surface aeration reacted with sulfide with ease. In addition, higher sulfate production and lower yield of microorganism could be observed under the same condition. It was possible to obtain reliable reaction stoichiometry for autotrophic denitrification by establishing pure anoxic condition. Linear relationship between bacterial growth and consumption of nitrate, sulfide, alkalinity, and sulfate production enabled to derive a relatively correct reaction stoichiometry for autotrophic denitrification when sulfide was used as an electron donor.

• 상하수도학회지
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• 제21권1호
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• pp.37-46
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• 2007

A feasibility test was conducted to evaluate the addition of turbidity substance in a coagulation process to remove natural organic matters (NOM), the precursor of disinfection by-products (DBPs). The experimental water sources were synthetic water containing 5 mg/L of humic acid and 50 mg/L of NaHCO3 and drinking water resource of Ulsan city (S Dam water, D Dam water and Nak-Dong raw water). The examined turbidity substances were kaolin, acid clay, and modified clay (0.38 meq $NH_4{^+}-N/g$ clay). In Jar tests at different concentrations of the turbidity substances (5, 10, 15, 20, 30 mg/L) using the synthetic water, the turbidity substances improved the removal of turbidity, UV-254 absorbance and dissolved organic carbon (DOC) by 23.8-38.1%, 17.0-24.5% and 2.5-44.5%, respectively. The modified clay showed higher removal efficiencies than other substances. In Jar tests using the drinking water, 10 and 20 mg/L of modified clay enhanced the removal efficiencies of turbidity, UV-254 absorbance, DOC, trihalomethane formation potential (THMFP), and haloacetic acid formation potential (HAAFP) by 3.0~4.3%, 19.1~29.0%, 12~34.9%, 4.9~36.7%, and 1.6~30.2%, respectively.