• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.101-111
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• 2017

The objective of this study is to determine the effectiveness of a modified air-side economizer in improving indoor air quality (IAQ). An air-side economizer, which uses all outdoor air for cooling, affects the building's IAQ depending on the outside air quality and can significantly affect the occupants' health, leading to respiratory and heart disease. The Air Quality Index (AQI), developed by the US Environmental Protection Agency (US EPA), measures air contaminants that adversely affect human beings: PM10, PM2.5, SO2, NO2, O3, and CO. In this study, AQI is applied as a control for the operation of an air-side economizer. The simulation is analyzed, comparing the results between the differential enthalpy economizer and AQI-modified economizer. The results confirm that an AQI-modified economizer has a positive effect on IAQ. Compared to the operating differential enthalpy economizer, energy increase in an operating AQI-modified economizer is 0.65% in Shanghai and 0.8% in Seoul.

• The Journal of Engineering Geology
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• v.21 no.3
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• pp.259-269
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• 2011

Concentrations of uranium (U) and radon (Rn) were measured in groundwater from 74 wells in the Icheon area, with the aim of determining the range and distribution of concentrations in an area underlain by granite (in this case, the Icheon granite). U concentrations ranged from 0.02 to 1,640.0 ${\mu}g/L$ (median value, 2.03 ${\mu}g/L$) and Rn concentrations ranged from 40 to 23,400 pCi/L (median value, 4,649 pCi/L). U concentrations in 10.8% of the samples exceeded 30 ${\mu}g/L$, which is the maximum contaminant level (MCL) proposed by the US Environmental Protection agency (EPA), based on the chemical toxicity of U. In addition, U concentrations in 59.5% and 13.5% of the samples exceeded 4,000 pCi/L (the Alternative MCL (AMCL) of the US EPA) and 8,100 pCi/L (Finland’s guideline level), respectively. We found no significant correlations between U (Rn) and other constituents, except for U-$HCO_3$ (correlation coefficient of 0.71), U-Ca (0.69), U-Li (0.45), U-Sr (0.43), and U-F (0.42). U and Rn contents in the groundwater are low relative to those in areas in other countries with similar geological settings, possibly due to the inflow of shallow groundwater to the wells in the Icheon area.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.637-637
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• 2012

본 연구에서는 내수침수 저감을 위하여 효율적(effective)인 우수저류조 설치에 따른 침수저감효과 극대화 방안을 제시하고자 한다. 여기서 효율성(effectiveness)은 침수저감량의 극대화 측면과 비용의 최소화 측면 두 가지로 구분된다. 최적 방재 시설물의 설치는 단순 설치비용 대비 저감량이 가장 큰 안을 제시하는 것은 의미가 없으며 일정 기준 이상의 방재성능을 발휘하면서 주어진 예산안에서 최적안을 찾아야 하므로 비용의 최소화 측면과 침수 저감량, 즉 맨홀에서의 월류 저감량을 최대화 하는 두 가지의 목적을 동시에 달성해야 한다. 따라서 본 연구에서는 다목적 최적화 알고리즘의 적용을 통하여 우수저류조 최적 설치지점을 선정하는 기법을 제안하였다. 본 연구에 적용한 다목적 최적화 방법으로는 목적함수의 최적해 탐색 효용성 측면에서 우수하다고 평가되고 있는 유전자 알고리즘을 적용하였다. 다목적 최적화의 경우 해의 우열을 판단하기 위한 적합도 함수는 실제 각 목적함수의 적합도 값(real fitness value)이 아닌 해의 상대적인 우열(dominance or non-dominance)에 따라 부여되는 등급(rank)에 의해서 해의 우열이 결정되며 여기서는 Fonseca and Fleming(1993)이 제안한 Ranking method를 적용하여 적합도를 결정하였다. 한편 도시 우수관망의 해석 및 우수저류조 설치에 따른 월류량 분석을 위하여 미 환경청(US Environmental Protection Agency; EPA)에서 제공하고 있는 EPA-SWMM 5.0 engine을 사용하였으며 최적화 알고리즘의 구성을 위하여 Visual C++와 SWMM DLL을 연동하여 사용하였다. 연구 대상유역은 인천 청라지구(3공구)를 대상으로 기법의 적용성을 검토하였으며 저류지 설치에 따른 비용함수는 EPA(2002)에서 제안한 저류지 체적대비 공사비용을 원화로 환산한 후 청라지구의 공시지가를 고려하여 결정하였다. 최적화 기법의 적용 결과 저류지 설치비용에 따라 최대로 월류량을 저감시킬 수 있는 우수저류조 최적 설치위치의 조합(Pareto-front)을 결정할 수 있었다.

• Journal of Environmental Science International
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• v.26 no.3
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• pp.345-362
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• 2017

The primary purpose of this study was to determine the risk of various disease outcomes due to exposure to cyanobacteria toxin (microcystin-LR) through drinking water in a Korean watershed. In order to determine the risk in a more quantitative way, the risk assessment framework developed by the National Research Council (NRC) of the United States (US) - hazard identification, dose-response relationship, exposure assessment, and risk characterization - was used in this study. For dose-response relationships, a computer software (BenchMark Dose Software (BMDS)) developed by the US Environmental Protection Agency (EPA) was used to fit the data from previous studies showing the relationship between the concentration of microcystin-LR and various disease outcomes into various dose-response models. For exposure assessment, the concentrations of microcystin-LR in the source water and finished water in a Korean watershed obtained from a recent study conducted by the Ministry of Environment of Korea were used. Finally, the risk of various disease outcomes due to exposure to cyanobacteria toxin (microcystin-LR) through drinking water was characterized by Monte-Carlo simulation using Crystall Ball program (Oracle Inc.) for adults and children. The results of this study suggest that the risk of disease due to microcystin-LR toxin through drinking water is very low and it appears that current water treatment practice should be able to protect the public from the harmful effects of cyanobacteria toxin (microcystin-LR) through drinking water.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.82-92
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• 2013

This study has investigated naturally occurring radioactive materials (N.O.R.M; $^{238}U$, $^{222}Rn$) for 353 drinking groundwater wells in metamorphic rock areas in Korea. Uranium concentrations ranged from N.D (not detected) to 563.56 ${\mu}g/L$ (median value, 0.68 ${\mu}g/L$) and radon concentrations ranged from 108 to 11,612 pCi/L (median value, 1,400 pCi/L). Uranium and radon concentrations in the groundwater generally are similar to USA with similar geological setting. Uranium concentrations in 9 wells (2.6%) exceeded 30 ${\mu}g/L$, which is the maximum contaminant level (MCL) by the US environmental protection agency (EPA), radon concentrations in 46 wells (13%) exceeded 4,000 pCi/L, which is the Alternative MCL (AMCL) by the US.EPA. The log-log correlation coefficient between uranium and radon was 0.32. The correlation coefficient between uranium and pH was 0.12 and the correlation coefficient between radon and temperature was -0.01. The correlation coefficient between uranium and $HCO_3$ was 0.09 and the correlation coefficient between uranium and Ca was 0.11. The median value of uranium was high Chung-Buk (1.78 ${\mu}g/L$), Gyeong-Buk (1.37 ${\mu}g/L$), In-Cheon (1.06 ${\mu}g/L$) for each province. On the other hand, the median value of radon was high In-Cheon (2,962 pCi/L), Chung-Buk (2,339 pCi/L), Jeon-Buk (2,165 pCi/L) for each province. Jeon-Buk for log-log correlation coefficient is the highest (0.63) among provinces.

• Economic and Environmental Geology
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• v.47 no.3
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• pp.219-225
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• 2014

In Korea, there are 1,474 thousand pumping wells nationwide which account for about 12% of total water use in 2012. As much as 39 hundred million tons of groundwater were used while 333 hundred million tons of total water were supplied in 2012. Because the water management authority projects that water demand will exceed supply by 2021, the authority is planning to extensively expand groundwater use in accordance with economic feasibility. Using the basic frameworks of cost-benefit analyses of the World Bank and the US Environmental Protection Agency (US EPA), the objective of this study is to examine the costs and benefits of the expansion of Korea's groundwater extraction through pumping wells. We conclude that the BC ratio of the groundwater pumping wells is 2.98. This signifies that the benefits are 2.98 times higher than the costs. The benefits include use and non-use values of pumping wells while the costs include the installation and maintenance of new wells, in addition to the restoration and pollution costs of abandoned wells, as well as fees for water quality tests, etc.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.495-508
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• 2019

We measured the concentrations of natural radionuclides (uranium and radon) and major elements in groundwater collected from forty wells located in Wonju area to investigate the hydrochemistry and the occurrence of these radionuclides. The range of electrical conductivity (EC) value in the study area was 73~400 μS/cm. In addition to the increase of EC value, the content of cations and anions also tends to increase. Uranium concentrations ranged from 0.06~50.5 ㎍/L (median value, 1.55 ㎍/L) and radon concentrations ranged from 67~8,410 pCi/L (median value, 1,915 pCi/L). Uranium concentrations in 3 well, 7.5% of the samples, exceeded 30 ㎍/L, the maximum contaminant level (MCL) proposed by the US Environmental Protection Agency (EPA), based on the chemical toxicity of uranium. Radon concentrations in 9 wells, 22.5% of the samples, and 1 well, 2.2% of the samples, exceeded 4,000 pCi/L (AMCL of the US EPA) and 8,100 pCi/L (Finland's guideline level), respectively. Concentrations of uranium and radon related to geology of the study area showd the highest values in groundwater of the biotite granite area. Uranium and radon contents in the groundwater are comparatively low compared to those in other countries with similar geological settings. It is likely that the measured value was lower than the actual content due to the inflow of shallow groundwater by the lack of casing and grouting.

• Korean Journal of Hydrosciences
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• v.5
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• pp.99-114
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• 1994

Three purposes of this study are as follows : The first was the development of the extension method for the limited data observed in an urban drainage basin. The second was the analysis of the correlation between storm water runoff and NPS(non-point source) Pollutant discharge. The last was the calculation of the monthly and annual specific NPS loads using the established correlation. The selected model was the SWMM(Storm Water Management Model) developed by the US EPA(Environmental Protection Agency). As a result of this study, the best correlation between storm water runoff and NPS pollutants discharge was produced by the nonlinear correlation between runoff rate(mm/hr) and specific loads rate(kg/ha) for all pollutants studied : SS, COD, BOD, and TN. The best correlation through the analysis based on evently total mass was made by the linear correlation between the by the nonlinear correlation for CASE2. The NPS annual specific loads for the urban basin studed were 4,993 kg/ha/year for SS, 775 kg/ha/year for BOD, 3,094 kg/ha/year for COD, 257 kg/ha/year for TN, respectively. And the proportion of the NPS annual specific loads to the total annual specific loads were 41 % for SS, 13 % for BOD, 29 % for COD, and 21 % for TN.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.2
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• pp.209-222
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• 2006

Odor problems brought about by deteriorating air quality occur in areas surrounding landfills because VOCs emissions from landfills are exhausted through surface soil and gas vents. Due to these factors, monitoring of VOCs emissions from landfills are essential. However, only a few studies have been carried out to assess VOCs emissions from landfills. A comprehensive approach to this problem is definitely warranted. In this study, we estimated BTEX emissions from 7 landfill sites in Korea using field experiments and LandGEM(Landfill Gas Emission Model), which is the USA EPA(Environmental Protection Agency)-recommended model for landfill gas emission estimation. For this purpose, we suitably modified the model's major input parameters $L_0$ and k according to 3 classes based on landfill scale after considering the characteristics of field experiments and LandGEM data. Consequently, we estimated VOCs emissions from landfills for cities, provinces and all of Korea alter modifying $L_0$ & k using LandGEM. Through the results of this study, we obtained essential basic data with respect to present conditions which will help us understand VOCs emissions from landfills in Korea.

• Water for future
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• v.26 no.3
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• pp.125-135
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• 1993

This study was conducted for two purposes. The first was the selection of the proper model for the urban runoff, and NPS(non-point source) loads and the second was the adjustment of the selected model through the calibration and the verification of the observed data on an urban drainage basin. The selected model for this study was the Storm Water Management Model(SWMM) developed and maintained by the US Environmental Protection Agency(EPA). In particular, the Runoff Block for the surface discharge and the Transport Block for the flow routing was used. The study basin is Youngdu basin, which is a typical developed urban drainage basin. The four rainfall events for the runoff and the two for the four NPS pollutants(SS, BOD, COD and TN) were used for the calibration and the estimation of the model parameters. This study performed the calibration with regard to the peak discharge, the time to peak discharge, the volume and the relative error for three items. It was shown that SWMM can successfully be used for the prediction of the runoff and the NPS pollutants discharge. The result of this study can be used as the basis for the analysis of the correlation between the runoff and the NPS pollutants discharges, and the analysis of the mass balance with the monthly and annual NPS loads in an urban drainage basin.