• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1147-1149
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• 2005

• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.96-108
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• 2018

Large efforts have recently been made on research and development of sustainable and energy-efficient short-cut nitrogen removal processes owing to strong attention to the energy neutral/positive wastewater treatment system. Anaerobic ammonium oxidizing bacteria (anammox bacteria) have been highlighted since 1990's due to their unique advantages including 60% less energy consumption, nearly 100% reduction for carbon source requirement, and 80% less sludge production. Side-stream short-cut nitrogen removal using anammox bacteria and partial nitritation anammox (PN/A) has been well established, whereas substantial challenges remain to be addressed mainly due to undesired main-stream conditions for anammox bacteria. These include low temperature, low concentrations of ammonia, nitrite, free ammonia, free nitrous acid or a combination of those. In addition, an anammox side-stream nitrogen management is insufficient to reduce overall energy consumption for energy-neutral or energy positive water resource recovery facility (WRRF) and at the same time to comply with nitrogen discharge regulation. This implies the development of the successful main-stream anammox based technology will accelerate a conversion of current wastewater treatment plants to sustainable water and energy recovery facility. This study discusses the status of the research, key mechanisms & interactions of the protagonists in the main-stream PN/A, and control parameters and major challenges in process development.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.5
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• pp.29-38
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• 2006

Geographic Information System has extended to higher assessment of water resources. GIS linking with hydrological model becomes a trend in water resource assessment modeling. One of the most popular models is SWAT2000 which have effectiveness in multi-purpose processes for predicting the impact of land management practices on water, sediments and chemicals yields in large complex watershed with varying soils, land uses, and management conditions over long period of time. In this study, SWAT2000 model was applied to Gap stream watershed in Daejeon city where TMDL (Total Maximum Daily Load) Regulation would be implanted. The Gap Stream watershed was partitioned into 8 subbasins, however, only 3 out of 8 subbaisns were observed for having practical gauged data on the basis of streamflow from the year of 2002 to 2005. Gauged streamflow data of Indong, Boksu and Hoeduck stations were used for calibration and validation of the SWAT Streamflow simulation. Estimation Efficiency Analysis (COE), Regression Analysis ($R^{2}$), Relative Error (R.E.) were used for comparing observed streamflow data of the 3 subbasins on the daily and monthly basis with estimated streamflow data in order to fix optimized parameters for the best fitted results. COE value for the daily and monthly streamflow was ranged from 0.45 to 0.96. $R^{2}$ values for daily and monthly streamflow ranged from 0.51 to 0.97. R.E. values for total streamflow volume ranged from 3 % to 22.5 %. The accuracy of the model results shows that the SWAT2000 model can be applicable to Korean watersheds like the Gap Stream watershed that needs to be partitioned into a number of subbasins for TMDL regulation.

• Journal of Korean Port Research
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• v.15 no.1
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• pp.107-119
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• 2001

Disaster mitigation, especially as a concept similar to damage mitigation caused by heavy rainfalls and flood is closely related to long-term development plan. This plan of an harbor area where is located in lower region is established and carried under consideration of disaster mitigation concept such as internal drainage and so on. Flood damage is somewhat predictable in accordance with height, stream and rainfall characteristics of the region. Therefore it is necessary to establish national and urban plan under consideration of this fact. But this consideration of existing regulation and institution is insufficient and improvement of regulation and institution is needed. This consideration of disaster mitigation fields is regulated declaratively and inclusively in national plan which is established in broad region, and specifically and detailedly in urban plan which is established in narrow region. The program to improve regulation and institution is proposed in order to consider disaster mitigation fields as a level of this plan.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.359-366
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• 2012

Accurate predictions about the water quality of a river have great importance in identifying in-stream flow and water supply requirements and solving relevant environmental problems. In this study, the effect of water release from upstream dam on the downstream water quality has been investigated by applying a hydological model combined with QUAL2E to Geum River basin. The ESP (Ensemble Stream Prediction) method, which has been validated and verified by lots of researchers, was used to predict reservoir and tributary inflow. The input parameters for a combined model to predict both hydrological characteristics and water quality were identified and optimized. In order to verify the model performance, the simulated result at Gongju station, located at the downstream from Daecheong Dam, has been compared with measured data in 2008. As a result, it was found that the proposed model simulates well the values of BOD, T-N, and T-P with an acceptable reliability.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.1
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• pp.27-38
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• 2006

In this study, we developed a program to estimate discharge efficiently considering major hydraulic characteristic including water level, river bed, water slope and roughness coefficient in a natural river. Stream discharge was measured at Gongju gauge station located in the down stream of the Daechung Dam during normal and dry seasons from 2003 to 2004. The developed model was compared with the results from the existing rating curve at T/M gage stations, and was used for runoff analyses. Evaluating the developed river discharge estimation program, it was applied during 1983-2004 that base flow separation method and RRFS (Rainfall Runoff Forecasting System) which is based on SSARR (Streamflow Synthesis And Resevoir Regulation). The result presents the stage-discharge curve creator range at the Gong-ju is overestimated by approximately $10-20\%$, especially at the low stage. It is attributed to the hydraulic characteristics at the study. The discharge simulated by the RRFS and base flow separation, which is calibrated using the measurement at the early spring and late fall season during relatively d]v season, shows the least errors. The coefficient of roughness at Gongju station varied with the high and low water level.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.115-119
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• 2003

Pollutants from industry, mining, agriculture, and other sources have contaminated sediments in many surface water bodies. Sediment contamination poses a severe threat to human health and environment because many toxic contaminants that are barely detectable in the water body can accumulate in sediment at much higher levels, the purpose of this study was to make convenient sampling method and optimal treatment of sediment for water quality improvement in reservoir or stream based on an evaluation of degree of contamination. Results for analysis of S-reservoir sediments were observed that copper concentration of almost areas were higher than the regulation of soil pollution (50 mg/1) for the riverbed. S-stream sediments were observed that copper, arsenic and TPH concentration of almost areas were exceeded soil pollution concerning levels for factorial areas. We used Remscreen(version. 1.0) program which is contaminated soil recovery program to select optimal treatment method of contaminant sediments. The result was shown in the order of Thermal Calcination > Excavation, Retrieval and Off-site Disposal(comparative less then contaminant) > Low Temperature Thermal Desorption + Solidification/Stabilization.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.775-782
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• 2000

Water quality models can be applied to manage the regional water quality problems and to estimate the target and allowable pollution load in watershed effectively. Since the models such as QUAL2E, W ASP5 and HSPF need many data and are not easily applied in real systems, the water quality model, which would be simple and easily applicable, has been required. Thus, an Analytical Model of BOD(AMB) considering travel time of pollutant was developed for the total pollution load regulation in drainage basin. It was found that the main stream length of a sub-basin in the AMB should be shorter than 7km and the length of distributed pollutant load should also be shorter than 3.5km in a sub-basin. The basin in the AMB could be divided into sub-basins with almost same hydraulic characteristics and reaction rate constant satisfying the proposed stream length. The running results of the AMB in a small stream were very close to the results of QUAL2E, which is widely used one in the world. Therefore, the AlVIB can be used to regulate the total pollution load in drainage district by local government.rnment.

• Journal of Biosystems Engineering
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• v.21 no.2
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• pp.155-166
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• 1996

A direct injection sprayer was designed using the concepts of injection mixing and total flow control, flowrate-based system compensating for the variation of forwarding speed. A metered rate, proportionally to the actual diluent flow rate, of a tracer chemical was injected directly into the diluent stream. The injection of chemical may improve the precision and safety of chemical application process. The control system was evaluated for the variables of the control interval, tolerances and sensitivities of flow regulation valve and injection pump. Performance of the system was assessed as that the response time of flow rate, response time of injection rate, absolute steady state error, and the coefficient of variance(C.V.) of concentration were 8.5 and -0.53 seconds, 0.067 lpm(0.8%) and 3.15%, respectively, at optimal parameters of control interval of 1.0 sec, fast sensitivity of flow regulation valve, medium sensitivity of injection pump and medium tolerance of flow rate. Performance of the system can be improved by increasing the sensitivity of flow regulating valve and employing a high resolution velocimeter, such as Doppler radar.

• Journal of Wetlands Research
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• v.21 no.spc
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• pp.90-97
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• 2019

In recent years, flood due to the consecutive storm events have been occurred and property damage and casualties are in increasing trend. This study calls the consecutively occurred storm events as a mega rainfall scenario and the discharge by the scenario is defined as a mega flood discharge. A mega rainfall scenario was created on the assumption that 100-year frequency rainfall events were consecutively occurred in the Gyeongancheon stream basin. The SSARR (Streamflow Synthesis and Reservoir Regulation) model was used to estimate the mega flood discharge using the scenario in the basin. In addition, in order to perform more reasonable runoff analysis, the parameters were estimated using the SCE_UA algorithm. Also, the calibration and verification were performed using the objective functions of the weighted sum of squared of residual(WSSR), which is advantageous for the peak discharge simulation and sum of squared of residual(SSR). As a result, the mega flood discharge due to the continuous occurrence of 100-year frequency rainfall events in the Gyeongan Stream Basin was estimated to be 4,802㎥/s, and the flood discharge due to the 100-year frequency single rainfall event estimated by "the Master Plan for the Gyeongancheon Stream Improvement" (2011) was 3,810㎥/s. Therefore, the mega flood discharge was found to increase about 992㎥/s more than the single flood event. The results of this study can be used as a basic data for Comprehensive Flood Control Plan of the Gyeongan Stream basin.