• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.52-57
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• 2013

Radon, which is one of the radioactive elements in the natural world, exists in the atmosphere and water. When this element inflows into the human body, it carries the risks of developing lung cancer and stomach cancer. Therefore, in this study, an effective 10 L scaled reactor was produced to mitigate radon in water and the radon mitigation efficiency in water following the changes in water temperature and amount of aeration were evaluated. Based on this, the radon mitigation efficiency (SRRR; Specific radon removal rate) was derived per unit air volume. According to the study result, when water temperature increased from $10^{\circ}C$ to $16^{\circ}C$, the SRRR value increased from 95 $nCi/m^3{\cdot}L$ to 134.4 $nCi/m^3{\cdot}L$, and when the amount of aeration increased from 0.2 L/min to 1 L/min, the SRRR value decreased from 198.1 $nCi/m^3{\cdot}L$ to 72.2 $nCi/m^3{\cdot}L$. Therefore, based on the experimental results, it is considered that it can be applied as a examination factor and objective indicator during the design of future radon-in-water mitigation systems.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.119-122
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• 1998

Chemical analysis, measurement of pumping rates of 60 production wells and depth to water tables of 57 monitoring wells were carried to protect depletion of water resources and deterioration of water quality for the commercial portable ground-water. Borehole depth of production well averages 149m(31 boreholes), casing depth is 28m(29 boreholes), production rate is 70 $m^3$/day and depth to water table of monitoring well is 23.26m, respectively. The geology of 60 wells can be divided into Daebo granite(20), Okchun metarmorphic complex(18), Precambrian granitic gneiss(15), Bulguksa granite(4), Cheju volcanics(2), Cretaceous sedimentary rock(1). Average electrical conductivity and pH are 152$\mu$S/cm, and 7.35, respectively. The contents of major cation and anion predominantly $Ca^{2+}$>N $a^{+}$>M $g^{2+}$> $K^{+}$ and HC $O_{3}$$^{－}$ >S $O_{4}$$^{2-}$>Cl￣>F￣. Water type is predominantly $Ca^{2+}$-HC $O_{3}$$^{－}$(81.7%). It's possible that water chemistry of some wells were affected not only by the geology of boreholes penetrated but by inflows of surface water or shallow ground-water. Therefore, it is strongly necessary to steadily monitor the water quality and hydrogeologic conditins of production wells.ells.ls.ells.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.195-202
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• 2006

Hydro-environmental impact assessments (HEIA) in tunnel constructions have been performed through various methods including preliminary investigations, field tests, numerical simulations, and monitoring. Specially, it is very important to evaluate quantitatively groundwater inflows into tunnels as well as drawdowns caused by tunnelling. Obvious definitions between porous and fractured rock media in hvdrogeologic properties of study regions must be needed to execute HEIA for rational tunnel construction in fractured bedrocks. In this paper, we propose a HEIA on tunnel constructions in fractured rocks media resulted from various hydrogeologic field tests and numerical models on given regions and determination of systematic order, i.e. the technical road map (TRM) of HEIA. These systematic HEIAs are expected to be usefully applied to base data in tunnel construction in fractured rock media.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.617-636
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• 2015

The Mokpo coastal waters receive discharges from three artificial lakes(Youngsan, Youngam, Geumho) and other terrigenous freshwater inflows(streams, sewage treatment effluent, fresh groundwater), which exhibit very high concentrations of nutrients and/or organic matters. To understand spatial distributions of nutrients(DIN, DIP, DSi) and other water quality parameters(Chl-a, water temperature, salinity, DO, COD, SS), field surveys were conducted at 10 stations in the Mokpo harbor and adjacent estuaries on May, July, September, and November 2008 within 10 days following discharge events from artificial lakes. In this study, the freshwater flow rate influxed by the operation of sea dike sluice had significant influence on water qualities of the Mokpo coastal waters, although nutrient concentrations in other freshwater sources such as streams, sewage treatment effluent, and fresh groundwater were much higher. As a result of statistical analysis, DIN, COD, and Chl-a had a negative correlation with salinity. Therefore it was shown that discharge extents, time, and nutrients from the Youngsan lake were major impact factors dominating the spatial characteristics of nutrients and other water quality parameters in the Mokpo harbor and adjacent waters. However, despite non-discharge from the Youngsan Lake on September of this investigated period, it was observed that the nutrient addition was taking place in the lower layer of the estuary suggesting nutrient supply through different pathways. This result has emphasized the need to implement the combined assessment about the cumulative impacts on the Youngsan Estuary environment and ecosystem due to freshwater inputs derived from the artificial lakes as well as other terrigenous inflows, or benthic releases.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.164-175
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• 2019

The Tor Tong Daeng Irrigation Project with the irrigation area of 61,400 hectares is located in the Ping Basin of the Upper Central Plain of Thailand where farmers depended on both surface water and groundwater. In the drought year, water storage in the Bhumipol Dam is inadequate to allocate water for agriculture, and caused water deficit in many irrigation projects. Farmers need to find extra sources of water such as water from farm pond or groundwater as a supplement. The operation of Bhumipol Dam and irrigation demand estimation are vital for irrigation water allocation to help solve water shortage issue in the irrigation project. The study aims to determine the smart dam operation system to mitigate water shortage in this irrigation project via introduction of machine learning to improve dam operation and irrigation demand estimation via soil moisture estimation from satellite images. Via ANN technique application, the inflows to the dam are generated from the upstream rain gauge stations using past 10 years daily rainfall data. The input vectors for ANN model are identified base on regression and principal component analysis. The structure of ANN (length of training data, the type of activation functions, the number of hidden nodes and training methods) is determined from the statistics performance between measurements and ANN outputs. On the other hands, the irrigation demand will be estimated by using satellite images, LANDSAT. The Enhanced Vegetation Index (EVI) and Temperature Vegetation Dryness Index (TVDI) values are estimated from the plant growth stage and soil moisture. The values are calibrated and verified with the field plant growth stages and soil moisture data in the year 2017-2018. The irrigation demand in the irrigation project is then estimated from the plant growth stage and soil moisture in the area. With the estimated dam inflow and irrigation demand, the dam operation will manage the water release in the better manner compared with the past operational data. The results show how smart system concept was applied and improve dam operation by using inflow estimation from ANN technique combining with irrigation demand estimation from satellite images when compared with the past operation data which is an initial step to develop the smart dam operation system in Thailand.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.507-519
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• 2013

This study is to evaluate agricultural water supply capacity in Geum river basin (9,865 $km^2$), one of the 5 big river basin of South Korea using MODSIM-DSS (MODified SIMyld-Decision Support System) model. The model is a generalized river basin decision support system and network flow model developed at Colorado State University designed specifically to meet the growing demands and pressures on river basin management. The model was established by dividing the basin into 14 subbasins and the irrigation facilities viz. agricultural reservoirs, pumping stations, diversions, culverts and groundwater wells were grouped and networked within each subbasin and networked between subbasins including municipal and industrial water supplies. To prepare the inflows to agricultural reservoirs and multipurpose dams, the Soil and Water Assessment Tool (SWAT) was calibrated using 6 years (2005-2010) observed dam inflow and storage data. By MODSIM run for 8 years from 2004 to 2011, the agricultural water shortage had occurred during the drought years of 2006, 2008, and 2009. The agricultural water shortage could be calculated as 282 $10^6m^3$, 286 $10^6m^3$, and 329 $10^6m^3$ respectively.