• Journal of Korean Society of Environmental Engineers
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• v.28 no.12
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• pp.1265-1273
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• 2006

The environmental capacity and watershed pollution load reduction of Yongdam reservoir were estimated by the simulation of water quality variation process with the target water quality establishment, pollution load estimation and flow analysis. The potable raw water $I{\sim}II$, COD $1.0{\sim}3.0$ mg/L and TP $0.01{\sim}0.03$ mg/L were selected as the target water quality Yongdam reservoir water quality model was constructed with WASP5 contained 42 segments and the correlation of calibrated results were BOD 0.73, $PO_4-P$ 0.98. The environmental capacity for target quality COD 2.0 mg/L and TP 0.02 mg/L were BOD $131,880{\sim}4,694$ kg/d, TP $7,855 {\sim}167$ kg/d which were less than exists, and the related reduction ratios were BOD $51{\sim}62%$, TP $47{\sim}67%$ which were middle amount in exists. The load reduction ratios to meet the potable raw water $I{\sim}II$ were BOD $72{\sim}16%$, TP $78{\sim}36%$ in existing conditions and BOD $81{\sim}44%$, TP $84{\sim}52%$ in new conditions. BOD was the least one and TP was the second least in 4 results. The effects of the load reduction assignment to subbasin were dominant in TP but little in COD.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.565-574
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• 2005

It is used water quality data that was measured at Pyeongchanggang real time monitoring stations in Namhan river. These characteristics were analyzed with the water qualify of rainy and nonrainy periods. TOC (Total Organic Carbon) data of rainy periods has correlation with discharge and shows high values of mean, maximum, and standard deviation. DO (Dissolved Oxygen) value of rainy periods is lower than those of 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 qualify forecasting models were applied. LMNN, MDNN, and ANFIS models have achieved the highest overall accuracy of TOC data. LMNN (Levenberg-Marquardt Neural Network) and MDNN (MoDular Neural Network) model which are applied for DO forecasting shows better results than ANFIS (Adaptive Neuro-Fuzzy Inference System). MDNN model shows the lowest estimation error when using daily time, which is qualitative data trained with quantitative data. The observation of discharge and water quality are effective at same point as well as same time for real time management. But there are some of real time water quality monitoring stations far from the T/M water stage. Pyeongchanggang station is one of them. So discharge on Pyeongchanggang station was calculated by developed runoff neural network model, and the water quality forecasting model is linked to the runoff forecasting model. That linked model shows the improvement of waterquality forecasting.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.30-33
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• 2001

This study was carried out to estimate the runoff pollutant loadings for water quality management in Boryung freshwater reservoir watershed. The hydrological monitoring system were operated for water level measurement during $1999{\sim}2000$ and temporal variation of water quality constituents such as pH, EC, total nitrogen, total phosphorus were analysed, periodically. Monthly runoff volumes by TANK model and potential pollutant loadings calculated by unit method were compared with measured values.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.521-534
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• 2020

In this study, the variation of water quality was analyzed for six sites in major tributaries of the Nakdong River Basin. Standard-FDC (Flow Duration Curve) was developed using PM (Percentile Method), one of the statistical FDC estimation methods. The LDC (Load Duration Curve) was obtained using the developed FDC. The current method and the LDC evaluation method were compared and analyzed to evaluate the achievement of TWQ (Target Water Quality). Regarding the monthly flow rate variation, the five sites showed the distribution of the lowest flow rate between May and June, indicating a high probability of dry weathering of the streams. The variation of water quality confirmed the vulnerable timing of flow rate in each site, and it is therefore deemed necessary to plan to reduce T-P and TOC. A comparison and evaluation of TWQ showed that there was a difference between the TWQ values achieved by the two techniques. In addition, the margin ratio to the 50% excess ratio can be found in the LDC evaluation. The results of the LDC evaluation by section and by month showed whether or not the water quality was exceeded by flow conditions, along with the vulnerable sections and timing. Accordingly, it is judged that this method can be used for water quality management in TMDLs (Total Maximum Daily Loads).

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.743-752
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• 2009

One of the major problems associated with operation of domestic sewer lines involves hydraulic problems such as insufficient conveyance capacity, exceeding maximum velocity, and deficiency of minimum velocity. It has also been pointed out that influent concentration lower than design concentration of pollutants, which is mainly caused by unidentified inflow and infiltration, degrades the operational efficiency of many sewage treatment plants (STPs). A computer-added analysis method supporting a coupled simulation of sewage quality and quantity is essentially required to evaluate the status of existing STPs and to improve their efficiency by a proper sewer rehabilitation work. In this study, dynamic water quality simulations were conducted using MOUSE TRAP to investigate the principal parameters that governs the changes of BOD, ${NH_4}^+$, and ${PO_4}^{3-}$3- concentrations within the sewer networks based on data acquired through on-site and laboratory measurements. The BOD, ${NH_4}^+$ and ${PO_4}^{3-}$3- concentrations estimated by MOUSE TRAP was lower than theoretical pollution loads because of sedimentation and decomposition in the sewer. The results revealed that sedimentation is a most important factor than other biological reactions in decreasing pollutant load in the sewers of C-city. The sensitivity analysis of parameters pertaining to water quality changes indicated that the effect of the BOD decay rate, the initial DO concentration, the half-saturation coefficient of dissolved BOD, and the initial sediment depth is marginal. However, the influence of settling rate and temperature is relatively high because sedimentation and precipitation, rather than biological degradation, are dominant processes that affect water quality in the study sewer systems.

• Journal of Environmental Policy
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• v.9 no.2
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• pp.135-155
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• 2010

The purposes of the paper are to estimate welfare change from water quality degradation by using contingent valuation method in Namdae stream of Gangrung and identify what factors of Namdae stream are important to Gangrun citizens. The study results show their total WTP per year and per household, \117,040 to improve Namdae stream quality from grade 3 to grade 1, including monetary WTP \87,502 plus opportunity cost of volunteering time for protection campaign, \29,538. The amount of total welfare change from water quality degradation based on the total WTP estimated above is calculated to be \27 billion of which the amount, as a sort of damage cost from water quality degraded, is so huge. All projects and policies related to natural environments, therefore, should consider both indirect and direct effects from them because natural environments have the irreversibility once degraded or deteriorated and would ultimately be influential on humans, both current and future generations, with tremendous amounts of time and costs beyond our imagination.

• Journal of Wetlands Research
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• v.8 no.4
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• pp.33-40
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• 2006

The water of rivers and lakes in Korea is the main sources for drinking, industrial and agricultural purposes. However, various pollutants washed-off from watershed area make worse and worse the water quality. Particularly, the changes of land uses in watershed area is the main pollutant sources in many cases in Korea, it is usually called to nonpoint pollution sources. In this reason, the Ministry of Environment are programing the total maximum daily load for four major large rivers in order to improve the water quality by controlling the watershed area. Therefore, this research was performed to estimate the total pollutant input from watershed areas to lakes of Ganwol and Boonam located in Chungnamdo. The AGNPS water quality model and monitoring were used to estimate the pollutant loading rates with unit pollutant concentration of each land use. The main landuse of the research area are forest, wet and dry paddy field and small urban area. The research shows that the pollutant sources in Ganwol and Boonam lakes are from the various landuses. In this manuscripts, the results will provide important informations for mitigating the pollutants to the lakes.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.682-688
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• 2009

A plane field and a sloped field located at low-land plane and alpine areas, respectively, were monitored with respect to runoff, water quality and fertilizer uses from March to December, 2008. Runoff volume and Non-Point Source (NPS) loads were estimated and analyzed with respect to fertilizer uses. Total TN and TP loads from the sloped field were higher than those from plane field because of larger chemical uses in the alpine field than in the plane field. Organic matter load from plane field was higher than that from sloped field because more organic compost was applied to plane field than to sloped field. Event Mean Concentration (EMC) of measured water quality indices were relatively higher in both fields. Organic matter load per 1 mm rainfall were higher in plane field and TN and TP loads per 1 mm rainfall were higher in sloped field than those in respective comparing field. It was concluded that the type and application method of fertilizer could play an important role in the estimation of NPS pollution loads and the development of Best Management Practices (BMPs). However, it was recommended that long-term monitoring is necessary to better describe the relationship between fertilizer uses and water quality from agricultural fields because numerous natural and management factors other than fertilizer also affect runoff quality.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.451-454
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• 2000

Recently, the antiwashout underwater concrete has been increasingly used for underwater structure such as high strength massive concrete structures. However, Concrete has poor quality ad durability due to dilution with separating cementitious material. In this study, specimens were made with antiwashout underwater concrete replaced with mineral admixtures to improve their properties and were placed in air, water, and salt water. To estimation the chloride ion permeation in concrete, ASTM C 1202 Test was performed. The experimental results demonstrate that the increase of the admixtures improved the properties of antiwashout underwater concrete.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.76-82
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• 1998

It is necessary to calculate the accurate velocity from the hydraulic model for the reliable prediction of water quality changes in water supply system. To verify the hydraulic analysis of the water supply system, fluoride was used as a tracer to calculate the travel time from the injection point to the sampling points. Results from this field experiment indicate that fluoride can be a good conservative tracer while it showed a little longitudinal dispersion along the pipe lines. And the velocity from the model was verified by these travel times and calibrated by changing the ratio of the unaccountable water. When the ratio of the unaccountable water. When the ratio of the unaccountable water was 20%, the error between the estimation of hydraulic model and the real travel time was minimum.