• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.10-21
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• 1999

The purpose of study were to research the characteristics of water variation adding humic acids to distilled water after ozonation. Upon investigating pH variation with contact time after providing distilled water+air, distilled water+ozone and distilled water-humic acid-air in reactor, it reduced after 60 minute in inletting air and in spite of short contact time did suddenly in inletting ozone. TOC and UV-254 continued to increase with contact time of ozone and humic acids. $NH^{4+}-N$ did slowly increase or decrease after constant contact time of ozone, because $NH^{4+}-N$ was converted into $No^3-N$ by ozone. T-N did suddenly increase after 90minute, but T-P did rarely fluctuate for total experiment. Total 30 species of organic matter were detected by GS/MSD, but 14 species did really tend to increase except for matter identified in distilled water and blank test. Humic acids generated $aliphatic{\cdot}aromatic$ hydrocarbon, alcohol and amine etc., and did various matters without inflow course of contaminants.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1097-1107
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• 2003

The DAWAST model was originally developed to consider the variation of water storage in the unsaturated soil zone and it is a conceptual lumped model. Return flows from agricultural, domestic and industrial water were included to the original result of model simulation to calibrate model parameters of watershed runoff. Agricultural water demand was estimated only in paddy fields supposing that return flow responded at stream was originated from paddy fields. Domestic and industrial water demand was estimated by average daily water demand multiplied monthly variation coefficient. Daily inflow to the Daechung multipurpose dam was applied to verify the DAWAST model considered return flows. On annual average from 1983 to 2001, inflows were simulated to 652.5 mm with return flows considered, which was approached more closer to observed inflow of 667.3 mm, compared with case of 606.8 mm with return flows not considered.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.20-27
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• 2005

The seasonal variation of water quality was studied in the Hwabongcheon. It runs though a small catchment where shallow groundwater was contaminated with $NO_3-N$ by intensive livestock facilities. A direct inflow of animal waste and incoming of contaminated groundwater affected its water quality. In the dry season, an important factor of water quality in the Hwabongcheon was direct inflow of animal waste. In the wet season, concentrations of $NO_3-N$ in the Hwabongcheon were elevated in spite of being diluted by precipitation. It could be explained by the effect of increased incoming of contaminated groundwater and showed by oxygen and hydrogen isotope values. $NO_3-N$ concentration in the Cheongmicheon was lower than that in the Hwabongcheon, so it increased next a junction. This effect was intense in wet season because $NO_3-N$ concentration in the Hwabongcheon was high.

• Journal of Korea Water Resources Association
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• v.57 no.6
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• pp.385-392
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• 2024

By installing the gate at the estuary to prevent the inflow of seawater into the river, it was prevented the inflow of seawater into the river, but as a result, the velocity of the river was rapidly decreased, turning it into a river with almost stoped flow. Since a river must have flow to maintain its function, in this study, it examined improving the flow of the river through the operation of a gate in Simgok-cheon where is a river that has been closed by a hydrological system at the estuary and almost stoped flow. It was considered that if the gate are operated according to the tide level, it could be changed into a river through which water flows by raising it to 0.49 m/s, which is about 10 times faster than the current slow flow rate of 0.05 m/s while maintaining the highest or lowest target elevation.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.228-234
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• 2011

The goal of water quality management on stream and watershed is to focus not on discharged loads management but on a water quality management. Discharged loads management is not goal of water quality management but way for perform with total maximum daily loads management. It is necessary to estimate the relation between non-point source with stromwater runoff (NPSSR) and water quality to select a watershed where it is required to manage NPSSR for water quality improvement. To evaluate the effects of NPSSR on stream's water quality, we compare the aspects of water quality in dry and wet seasons using flow duration curve analysis based on flow rate variation data by actual surveying. In this study we attempt to quantify the variation characteristic of water quality and estimate the Inflow characteristic of pollution source with water quality and flow rate monitoring on 10 watersheds. We try to estimate water quality and flow rate by regression analysis and try again regression analysis with each high and low water quality data more than estimations. An analysis of relation between water quality and flow rate of 10 watersheds shows that the water quality of the Nonsan and the Ganggyeong streams had been polluted by NPSSR pollutants. Other eight streams were important point source more than NPSSR. It is wide variation range of $BOD_5$ also high average concentration of $BOD_5$. We have to quantify water quality variation by cv1 in wet season and cv365 in dry season with comparing the estimate of high water quality and low water quality. This method can be used to indicator for water quality variation according to flow rate.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.217-228
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• 1999

The three methods of analysis (i) REV(representative elemental volume), (ii) non-REV and (iii) joint network analysis are introduced in this paper to analyze the groundwater flow in jointed rock mass and the inflow into underground excavations. The results from those methods are compared one another to reveal their characteristics by varying the number of joints and the diameter of the opening. The pre-processor, the so-called sequential analysis, is introduced to predict the equivalent hydraulic conductivity of a jointed rock mass having a number of intersecting joints. Using the finite element mesh, joint map and sequential analysis, the equivalent hydraulic conductivities are calculated for all 445 elements. The hydraulic inhomogeneity and the determination of the representative properties of jointed rock masses are discussed. In the REV analysis where the entire rock mass is homogenized through the representative properties, the inflow is increased regularly and consistently by increasing the joint density, the opening size and the conductivity contrast value. Though the non-REV analysis showed irregular variation of the inflow due to the local inhomogeneity allowed to individual elements, the inflow approached the REV results as the characteristic length increases. The joint network analysis showed the most sensitive reaction to the joint density, the opening size and the presence of the network crossing the opening. The reliability of the network analysis depends on the geometric data of individual joints. In view of the limited field data on joint geometry and possible uncertainty the REV and non-REV methods are considered more practical and rational than the joint network analysis.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.2
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• pp.201-208
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• 2012

Wangsong Reservoir needs a systematic approach that can control water purity and water quality improvement. This study was carried out to assess the seasonal variation of water quality and the effect of pollutant being loaded from watershed in a sallow eutrophic reservoir(Wangsong Reservoir) from March to November, 2011. Wangsong Reservoir, located in Uiwang City, has the capacity of 2 million $m^{3}$ in irrigation water supply with the drainage of 4.2 $km^{2}$. Average concentrations of BOD, COD, T-N, T-P, and Chloropyll-a in Wangsong Reservoir were 5.8 mg/L, 9.7 mg/L, 4.299 mg/L, 0.106 mg/L and 73.1 mg/$m^{3}$, respectively. In the inflow streams and treated sewage of Wangsong Reservoir, the T-N concentrations of 4.114 - 14.619 mg/L were higher than those in the Reservoir and the other pollutants were lower. As a result of investigation, Wangsong Reservoir exceeded the agricultural water standard level due to algal growth and accumulation from the upper streams and sewage. In order to achieve the targeted water quality in Wangsong Reservoir, it is required to be decreased in pollutants of internal and inflow streams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.99-108
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• 1991

Rapid changes of urban hydrologic events need new management operation rule of detention reservoir which is essential outflow control system in urban area. Therefore, this study is to develop the outflow management method of Seoul city considering the Han river flood characteristics, to analyze the inundation of detention reservoir according to variation of design storm patterns, and to examine the safety of gate due to design flood water level. From this study, new operation rule is presented. The design storm patterns are determined by instantaneous intensity method and Huff's quartile method. And the inflow hydrograph of detention reservoir is obtained by applying ILLUDAS model and RRL method. The operation rule of existing drainage pump is designed to have linear relation between storage and pumping discharge. But in this study, it is effective for preventing inundation when the operation rule of drainage pump have Gaussian function which is combined the storage of detention reservoir with its inflow according to increasing or decreasing of inflow hydrograph.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.767-782
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• 2012

Accumulation of sediment within pipelines, manholes, and other components of urban sewer systems can have a bad influence on sewerage arrangements, such as the resistance of the passage of flows, the cause of urban flooding and the premature operation of combined sewer overflows, and the inevitable pollution of watercourses. Therefore, it is necessary to understand the movements and sedimentation of sediment loads in combining junction manholes by experiments. In this study, hydraulic experimental apparatus which can change the manhole shapes (square, circle) were installed to measure deposited sedimentation quantity. The quantity of deposited sediment loads was measured by different conditions, for instance, the inflow conditions of sediment (continuous and certain period), the amount of inflow sediment, and the variation of inflow pipe of sediment. The combining junction manhole that was set up a inclined benching have the considerable effect of reduction of sedimentation in manholes without apropos of the change of manhole shapes. Therefore, the improved manhole could be increased the drainage capacity of sewerage arrangements in urban sewer systems.

• Journal of Preventive Medicine and Public Health
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• v.50 no.1
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• pp.29-37
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• 2017

Objectives: The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization. Methods: We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates. Results: In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index. Conclusions: Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit.