• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.211-222
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• 2015

This study focused on evaluating the efficiency of the removal of non-point source pollution by Daecheong Lake Juwon Stream constructed wetlands. The constructed wetland system is a surface flow type designed in the year 2007 for purifying eutrophic water of Daecheong Lake Juwon Stream. The value of conductivity, suspended solids(SS), chemical oxygen demand using a potassium permanganate($COD_{Mn}$), five-day biochemical oxygen demand($BOD_5$), total nitrogen(T-N), total phosphorous(T-P), and pH in inflow averaged 220.2, 2.46, 3.33, 1.34, 2.00, 0.04 mg/L and 7.24, respectively and in outflow averaged 227.9, 1.12, 3.34, 0.87, 1.16, 0.02 mg/L and 7.45, respectively. The average removal efficiency of constructed wetlands was 30 % for SS, 22 % for $BOD_5$, 45 % for T-N and 31 % for T-P. The removal rates of SS, $BOD_5$ and T-N in the spring, summer and autumn were higher than those in winter. The removal rate of T-P was not significant different in all seasons. The amounts of pollutants removal in the constructed wetlands were higher in the order of $3^{rd}$ < $2^{nd}$ < $1^{st}$ wetland for SS and T-P, $2^{nd}$ < $3^{rd}$ < $1^{st}$ wetland for $BOD_5$ and T-N. Therefore, our findings suggest that the constructed wetlands could well treat the eutrophic Daecheong Lake Juwon Stream waters.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.618-625
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• 2008

Advanced Phase Isolation Ditch (APID) process was studied to develop economic retrofitting technology, for the plants where retrofitting of common activated sludge process is required. In this study, to evaluate the effluent BOD, SS, T-N, and T-P concentrations as process capable and stable parameters for treating municipal wastewater, a demonstration plant was installed and operated in the existing sewage treatment plant of P city. During this study, the average effluent BOD, SS, T-N, and T-P concentrations were 4.56, 5.20, 9.30, and 1.75 mg/L at the conventional mode and 3.95, 3.17, 7.65, and 1.18 mg/L at the modified mode. The modified mode (BOD: 3.69, SS: 3.19, T-N: 1.27, and T-P: 0.69) increased the process capability more than the conventional mode (BOD: 1.80, SS: 1.05, T-N: 2.17, and T-P: 0.15) in this study. If process capability over 1.0, this process is capable and stable to treat wastewater. Therefore, newly developed APID process with modified intermittent aeration mode can be one of the useful processes for stable organic matter and nutrients removal.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1618-1622
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• 2006

Bacteriophage T7 gp4A' is a ring-shaped hexameric DNA helicase that catalyzes duplex DNA unwinding using dTTP hydrolysis as an energy source. To investigate the effect of single-stranded DNA (ssDNA) on the kinetic pathway of dTTP hydrolysis by the T7 DNA helicase complexed with ssDNA, we have first determined optimal concentration of long circular M13 single-stranded DNA and pre-incubation time in the absence of $Mg^{2+}$ which is necessary for the helicase-ssDNA complex formation. Steady state dTTP hydrolysis in the absence of $Mg^{2+}$ by the helicase-ssDNA complex provided $k_{cat}$ of $8.5\;{\times}\;10^{-3}\;sec^{-1}$. Pre-steady state kinetics of the dTTP hydrolysis by the pre-assembled hexameric helicase was monitored by using the rapid chemical quench-flow technique both in the presence and absence of M13 ssDNA. Pre-steady state dTTP hydrolysis showed distinct burst kinetics in both cases, indicating that product release step is slower than dTTP hydrolysis step. Pre-steady state burst rates were similar both in the presence and absence of ssDNA, while steady state dTTP hydrolysis rate in the presence of ssDNA was much faster than in the absence of ssDNA. These results suggest that single-stranded DNA stimulates dTTP hydrolysis reaction by T7 helicase by enhancing the rate of product release step.

• Journal of Korea Water Resources Association
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• v.41 no.12
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• pp.1187-1198
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• 2008

Many reservoirs in Korea and their downstream environments are under increased pressure for water utilization and ecosystem management from longer discharge of turbid flood runoff compared to a natural river system. Turbidity($C_T$) is an indirect measurement of water 'cloudiness' and has been widely used as an important indicator of water quality and environmental "health". However, $C_T$ modeling studies have been rare due to lack of experimental data that are necessary for model validation. The objective of this study is to validate a coupled three-dimensional(3D) hydrodynamic and particle dynamics model (ELCOM-CAEDYM) for the simulation of turbid density flows in stratified Daecheong Reservoir using extensive field data. Three different groups of suspended solids (SS) classified by the particle size were used as model state variables, and their site-specific SS-$C_T$ relationships were used for the conversion between field measurements ($C_T$) and state variables (SS). The simulation results were validated by comparing vertical profiles of temperature and turbidity measured at monitoring stations of Haenam(R3) and Dam(R4) in 2004. The model showed good performance in reproducing the reservoir thermal structure and propagation of stream density flow, and the magnitude and distribution of turbidity in the reservoir were consistent with the field data. The 3D model and turbidity modeling framework suggested in this study can be used as a supportive tool for the best management of turbidity flow in other reservoirs that have similar turbidity problems.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.412-420
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• 2014

Water quality variations were investigated at 4 locations of Jungrang river (upper, middle and lower basins) during a period of 3 rainfall events. During the rainfall, concentrations of $COD_{Mn}$, SS and $BOD_5$ significantly increased, while the concentration of T-N decreased and that of T-P remained relatively constant. This pattern became more apparent as the level of accumulative precipitation and rainfall intensity increased. Simple regression analysis showed that the accumulative precipitation was positively correlated with all water quality pollutants except for T-N. With increasing accumulative precipitation, the concentration of T-N decreased, while the others increased. $R^2$ of simple regressions of hourly average rainfall intensity and water quality pollutants, showed wider range of variation ranged from 0.483 to 0.992, which indicated a strong correlation. The stronger the hourly average rainfall intensity, the more T-N and T-P in the upper basin, more $COD_{Mn}$ in the middle and lower basins, more SS with gradual increase from upper to lower areas, and more $BOD_5$ with gradual decrease from upper to lower region. Simple regression showed that water quality pollution in the upper basin was more sensitive to an increase of rainfall discharge than that in the middle and lower areas.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.425-433
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• 2011

In order to obtain optimum pre-treatment methods and improve T-N and T-P removal efficiencies, removal rates of pollutants in small-scale livestock wastewater treatment apparatus with water plant filtration bed or activated sludge tank were investigated. Based on the results from the optimum pre-treatment in small-scale livestock wastewater treatment apparatus, removal efficiencies of pollutants in livestock wastewater treatment plant with water plant filtration and activated sludge beds. The removal rates of COD, SS, T-N, and T-P in effluent were 83, 89, 63 and 87% in small-scale livestock wastewater treatment apparatus with water plant filtration bed, respectively. The removal rates of COD, SS, T-N, and T-P in effluent were 96, 95, 86 and 92% in small-scale livestock wastewater treatment apparatus with activated sludge tank, respectively. For increasing the COD, SS, T-N, and T-P removals in small-scale livestock wastewater treatment apparatus, the water plant filtration and activated sludge beds are recommended. In livestock wastewater treatment plant with water plant filtration ($1^{st}$ treatment) and activated sludge ($2^{nd}$ treatment) beds, the concentrations of COD, SS, T-N, and T-P in effluent were 39, 15, 42 and $1mg\;L^{-1}$, respectively. It was shown that the concentrations of COD, SS, T-N, and T-P met acceptable effluent quality standard for livestock wastewater. Based on the above results, the removal rates of COD, SS, T-N, and T-P in effluent were over 99.8, 99.9, 99.2, and 99.9% in livestock wastewater treatment plant, respectively.

• Environmental Analysis Health and Toxicology
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• v.6 no.3_4
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• pp.155-161
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• 1991

The water quality in Wonju stream, Seom river in Kangwon province and Bokha, Shindun stream in Kyeonggi province was investigated between the season of irrigation on July, 1990 and of non-irrigation on September in 1989. The results of water quality obtained from this study were as follows; As for water quality of the Wonju stream and the Seom river, the concentration of COD, T-N, SS and Cu, and for the Bokha, Shindun stream, the concentration of T-N, SS and Cu were exceeded standard levels of quality guideline of agricultural water use in the season of irrigation. However, in the water quality of Wonju and Bokha stream, the concentration of T-N , SS and Cu, and in the Seom river, the concentration of T-N, SS, Cu and Zn were exceeded standard levels of agricultural water quality in the season of non-irrigation. And the average water quality of the 4 streams were not suitable for agricultural water use. The comparison of the annual average water quality of the 4 streams for pH, DO, T-N and SS were in statistics significantly different with p values less than 0.01. When the average water quality between the season of irrigation and non-irrigation in each stream was compared, DO and COD in the Wonju stream, COD in the Seom river, pH, DO, T-N, SS and Cu in the Shindun stream showed a significant difference with p<0.01. The average in the sediment were; COD, 5.65∼26.53 ppm; Cu, 0.26∼0.49 ppm and Zn 0.95∼2.97 ppm. The concentration of three contaminants were markedly higher than the water quality. And the concentration of COD, Zn in the sediment showed a significant difference with p<0.01, and Cu showed a considerably significant difference with p<0.05.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.403-403
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• 2015

본 연구에서는 강우시 도로지역에서 발생하는 비점오염물질 유출 및 수질특성을 살펴보고자 도로지역(국도 46호선)을 대상으로 총 16회의 강우사상에 대해 분석하였다. 모니터링 기간(2014년 5월~9월)동안 연구대상지역에는 3.2~80.3 mm의 강우가 발생하였으며, 강우강도는 0.39~11.29 mm/hr의 범위로 나타났다. 선행무강우일수는 0.3~20.1일이며, 총 유출량은 0.1~6.8 ㎥, 유출율은 0.24~0.85(평균 0.6)의 범위로 나타났다. 강우 모니터링 결과, 유량가중평균농도(Event Mean Concentration, EMC)는 TOC 4.9~56.2 mg/L(평균 18.0 mg/L), BOD 3.1~21.5 mg/L(평균 7.5 mg/L), COD 6.7~58.6 mg/L(평균 23.6 mg/L), SS 2.1~281.9 mg/L(평균 59.4 mg/L), T-N 1.07~13.46 mg/L(평균 4.89 mg/L) 그리고 T-P 0.065~0.680 mg/L(평균 0.23 mg/L)의 범위로 나타났으며, 강우계급별로 살펴보면 0~10 mm일 때 BOD 9.3 mg/L, COD 30.5 mg/L, SS 84.1 mg/L, T-N 5.42 mg/L, T-P 0.27 mg/L로, 10~30 mm일 때 BOD 6.6 mg/L, COD 22.0 mg/L, SS 29.0 mg/L, T-N 4.9 mg/L, T-P 0.20 mg/L로, 50 mm 이상의 강우에서는 BOD 3.6 mg/L, COD 7.1 mg/L, SS 46.4 mg/L, T-N 3.42 mg/L, T-P 0.10 mg/L로 강우계급별 EMC는 대부분 수질항목에 있어 10 mm 이하 계급의 평균 EMC가 높은 수준으로 나타났다. 그리고 각 강우사상에 대한 단위면적당 오염부하는 TOC 0.06~3.5 kg/ha, $BOD_5$ 0.03~1.6 kg/ha, CODMn 0.09~4.74 kg/ha, SS 0.09~35.99 kg/ha, T-N 0.012~2.600 kg/ha, T-P 0.001~0.062 kg/ha의 범위로 산정되었다. 도로지역은 불투수층 면적비율이 높아 누적강우량 10 mm 이하에서도 유출이 발생하는 것으로 분석되었으며, 작은 강우에도 초기유출이 발생하고 유출되는 오염물질 농도가 높은 경향을 나타내었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.571-576
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• 2016

Asymmetric double gate(DG) MOSFET has the different top and bottom gate oxides thicknesses. It is analyzed the deviation of subthreshold swing(SS) and conduction path for the ratio of top and bottom gate oxide thickness of asymmetric DGMOSFET. SS varied along with conduction path, and conduction path varied with top and bottom gate oxide thickness. The asymmetric DGMOSFET became valuable device to reduce the short channel effects like degradation of SS. SSs were obtained from analytical potential distribution by Poisson's equation, and it was analyzed how the ratio of top and bottom oxide thickness influenced on conduction path and SS. SSs and conduction path were greatly influenced by the ratio of top and bottom gate oxide thickness. Bottom gate voltage cause significant influence on SS, and SS are changed with a range of 200 mV/dec for $0<t_{ox2}/t_{ox1}<5$ under bottom voltage of 0.7 V.

• KSBB Journal
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• v.24 no.4
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• pp.353-360
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• 2009

This study was accomplished using Anaerobic/Anoxic/Oxic upflow packed-bed column reactors with fixed media and Loop Reactor with fluidized media instead of Oxic reactor. The objectives of this study was to investigate the characteristics of organics, nitrogen and phosphorus removal from sewage with the HRT. The average removal efficiencies of $BOD_5$ and SS increase as increasing the hydraulic retention time (HRT) until 16 h of the HRT, and they were constant over 16 h of the HRT. The removal efficiency of $BOD_5$ in case of packed-bed reactor and Loop Reactor was about 86.6% and 90.9% respectively at 16 h of the HRT. The removal efficiency of SS in packed-bed reactor and Loop Reactor was about 78.0% and 88.2% respectively at 16 h of the HRT. The average removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ showed similar trends as those of $BOD_5$ and SS. At the HRT of 16 h, the removal efficiency of $COD_{Cr}$ in case of packed-bed reactor and Loop Reactor was 63.5%, 75.2% and that of $COD_{Mn}$ was 60.7%, 73.6% respectively. The average removal efficiencies of T-N and T-P increase as increasing the HRT. The removal efficiencies of T-N and T-P in Loop Reactor were 33.6% and 54.5% respectively at 16 h of the HRT and T-N and T-P were better removed in Loop Reactor. From this result, it was found that the performance of Loop Reactor was much higher than the performance of packed-bed reactor and the optimum HRT was 16 h.