• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.4
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• pp.155-167
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• 1996

동일한 하천의 용전산소량(DO)을 예측하는 경우에도 사용하는 재포기계수$(K^2)$는 계산하는 공식에 따라 커다란 차이를 나타매며, 부적합한 공식의 사용에 의한 $(K^2)$의 계산은 하천의 수질관리 정책결정에 지장을 초래하므로 현장사정에 적합한 공식의 개발이 필요하다. 이러한 공식의 개발은 많은 현장측정 자료를 사용하도록 신뢰성이 높으나 현장측정은 소요되는 비용에 제약을 받기 때문에 신뢰성과 경제성을 동시에 고려한 표본의 크기의 적정규모를 산정하는 것이 필요하다. 본 연구에서는 Monte Carlo 방법에 의해 통계적으로 수출된 $(K^2)$를 사용해서, 주어진 자료에 의해 개발된 공식을 사용할 때 야기되는 오차가 $(K^2)$개수의 증가에 따라 얼마나 감소하는지를 널리 사용되는 공식 중에 Owen공식과 Churchill공식을 New Jersey에 있는 Passaic River에 적용시켜 검토하였다. 표본의 크기가 10에서 20으로 증가할 때 오차가 크게 감소하였으며 20을 넘어 증가시켰을 때에는 오차의 감소폭이 미미하였다. 초차의 감호형태와 단위측정당 소요되는 비용을 고려할 때 약 20정도의 표본의 크기가 적정수준의 규모에 판단된다. 이러한 적용사례의 결과는 회귀모델의 이론적 계산결과에 의한 오차 감소와 흡사하여 본 연구결과는 여러 가지(K2)공식과 광범위한 하천의 조건에 적용이 가능할 것이며, 본 연구에서 사용한 적정표본의 크기 산정방법은 회귀분석에 의해 실험식을 개발하는 다른 분야에도 적용이 가능하다.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2003.04a
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• pp.160-160
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• 2003

• Water for future
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• v.17 no.2
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• pp.85-97
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• 1984

Measuring the river flow and water quality in the midstream of the Nakdong River, the natural purification status in examined through the analyses of the elements which affect the variation of dissolved oxygen, and DO model is evaluated to the midstream reach of the river. The major results of this study are as follows; the pruification factor of the of the river is relatively high, it is worried over eutrophication considering much production of algae, and it is evaluated that important factor affecting the DO value computed by the proposed DO model are in order of reaeration coefficient, carbonaceous BOD and deoxygenation constant.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.179-182
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• 2002

The objective of this study was to evaluate petroleum hydrocarbon degradation processes governing natural attenuation at tile contaminated site and accomplished through conducting on investigation of degradation rate, capacity, and mechanism of the monitored natural attenuation. The monitoring results of the three years indicated that the concentrations of DO, nitrate, and sulfate in the contaminated area were significantly lower than these in the none-contaminated area. The results also showed a higher ferrous iron concentration, a lower redox potential and a neutral pH in the contaminated groundwater, suggesting that biodegradation of TEX is the major on-going process in the contaminated area. However, reduction of TEX in the groundwater was not only biodegradation but also dilution and reaeration during infiltration of uncotaminated surface and groudwater.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.595-601
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• 2005

In this research, effects of water circulation on phosphorus release from sediment into water body were studied. Sediments sampled at the Daechung Lake were used for the column experiments with circulation and non-circulation conditions. Deaeration coefficient, $K_1$ and reaeration coefficient, $K_2$ of non-circulation condition were 0.133 and 0, respectively, while $K_1$ and $K_2$ for circulation condition were 0.46 and 0.018, respectively. Oxidation Reduction Potential (ORP) showed a linear relationship with dissolved oxygen (DO) when DO is over 2 mg/L. Phosphorus concentration induced by phosphorus release from sediment was highly dependent upon DO, ORP, and pH. Under anaerobic condition, phosphorus release rate was higher for $Fe^{2+}$-bounded phosphorus compared to that of $Ca^{2+}$-bounded phosphorus.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.780-780
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• 2012

하천에서의 1차원 수질해석에 널리 사용되는 QUAL2E 모형은 전체 대상구간을 요소(element)로 구성하고 다시 수리학적으로 유사한 흐름특성을 가진 구간(reach)으로 구분하고 있다. 각 구간에서는 동일한 유속과 수심이 형성되는 것으로 가정하고 있기 때문에 자연하도의 다양한 흐름변화, 특히 자연하천의 보나 낙차공으로 인한 국부적인 흐름상태를 모형에 반영하기 어려우며, 이로 인한 실제 흐름특성과의 차이는 수질모의 해석결과에도 다양한 영향을 미치게 된다. QUAL2E 모형에서는 이와 같은 보나 낙차공의 수리학적 특성을 반영하기 위해 댐 계수옵션이 있으며, 이를 통해 흐름으로 인한 폭기 현상을 재현하도록 되어 있다. 본 연구에서는 모형 내 재폭기 계수에 대한 민감도 검토를 수행하였으며, 한강의 팔당댐부터 한강대교까지를 대상구간으로 잠실수중보로 인해 발생하는 재폭기 현상에 관해 연구하였다. 본 연구는 보나 낙차공이 있는 하천에 대해 QUAL2E 모형을 적용할 경우 용존산소(DO)를 비롯한 여러 가지 수질변수의 정확도 높은 예측에 기여할 것으로 기대된다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.198-207
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• 1990

Among the biodegradable liquid waste treatment and disposal methods, ocean dumping is a cost-effective and productive manner considering reuse point of view However, when biodegradable liquid waste is dumped in the ocean, oxygen consumption by the decomposition of organic matter must be considered. The purpose of this study is to determine the maximum allowable concentration and dumping rate in the southern waters of the East Sea based on dissolved oxygen level. Streeter and Phelps' model has been used to determine the maximum allowable concentration. Factors in this model, deoxygenation constants and reaeration coefficients, have been determined by appling oxygen consumption method and closed system model. Deoxygenation constants and reaeration coefficients from surface to each standard depth are $0.24\~0.29/day\;and\;0.03\~0.39/day$ in summer, $0.17\~0.20/day\;and\;0.04\~0.56/day$ in winter, respectively. The allowable organic matter concentration($mgBOD/\iota$) to the dissolved oxy-gen sag value of $5mg/{\iota}$ is represented $17.23\times(H)^{-0.37}$ in summer, and $64.96\times(H)^{-0.52}$ in winter by mixing depth(H, m). Csanady's experiment has been applied to estimate the optimum dumping rate. The optimum dumping rate($R,\;m^3/sec$) can be written as a product of the beam(b, m) and the draft(h, m) of vessel, and biochemical oxygen demand of waste($L_n,\;mg/{\iota}$) $R=275{\times}bh^{0.63}L_n^{-1}$ in summer $=745{\times}bh^{0.48}L_n^{-1}$ in winter. The difference of dumping rate between in summer and winter is due to the oxygen distribution.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.331-339
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• 2006

This research was carried out to understand the impacts of thickness of sand capping to control phosphorus release from sediment into overlying water. As capping effectively retards release flux, phosphorus concentration in water body can be maintained if phosphorus release rate was kept under microbial degradation rate. With capping thickness increases, deaeration rate become less, while reaeration coefficient become higher. Phosphorus release rate and capping thickness were linearly correlated. The results of regression analysis indicated that phosphorus release can be controlled effectively by sand capping of least 20${\sim}$40 mm thickness.

• Proceedings of the Korea Water Resources Association Conference
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• 1987.07a
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• pp.159-168
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• 1987

Temporal and spatial prediction of water quality provides the necessary information to a profect planning, design, and model optimization for water quality mangement in a river system. In thes study, the QUAL II model is applied to the Keum River system from the downstream of Dae-Chong dam to the Great Pak-Je bridge. The advection-dispersion model of water quality based on the material balance and the numerical solution method of the model are presented. The enhancement of the model application is empha sized by comparing the observed and the simulated values of BOD, DO, and water temperature. Through these processes, the water quality states of the Keum River system are evaluated and the deoxignation rate, the reaeration rate, and Fair value are estimated. Also, the maintance of the target DO level with the control of the discharge from Dae-Chong dam is discussed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.55-63
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• 1997

Constructed wetland system which can be applied to the rural wastewater treatment system was examined by pilot plant in Kon-Kuk University. Hydraulic loading rate of wastewater was about 0.16m$^3$/m$^2$. day and theoretical detention time in the system was 1.38 days. The effluent of the septic tank for the school building was applied as inflow to the system. The influent concentration of DO was zero but effluent was up to 4.37mg/${\ell}$ which implies that oxygen was supplied enough from atmosphere by reaeration to support biological activity of the system. Average influent concentration of BOD was 104mg/${\ell}$ and effluent was 24mg/${\ell}$ with average removal rate of 76%. Average influent concentration of COD was 215mg/${\ell}$ and effluent was 63mg/${\ell}$ with average removal rate of 70 % . Average influent concentration of SS was 78mg/${\ell}$ and effluent was 10mg/${\ell}$ with average removal rate of 87%. Two components, BOD and SS, are regulated by law to keep maximum water quality standard of 80mg/${\ell}$ when daily outflow rate is less than 100$m^3$/day which is the case of most rural communities. Therefore, the results from the experiment showed that constructed wetland system can meet the water quality standard easily. Average influent concentration of total nitrogen was 165mg/lwhich is relatively higher than normal wastewater, and effluent was about 156mg/${\ell}$ with average removal rate of only 6%. Average influent concentration of total phosphorus was 41 mg/${\ell}$ and effluent was 6mg/${\ell}$ with average removal rate of 87%. Overall, constructed wetland system was thought to be effective to treat wastewater if nitrogen removal mechanism is improved. Considering low cost, less maintenance, and high treatability, this system can be a practical alternative for the wastewater treatment in rural area The experiment was performed during the summer and fall season, and treatment efficiency of the system is expected to decrease in low temperature. therefore, further study including temperature is required to evaluate feasibility of the system more in detail.