• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2006년도 추계학술대회 논문집
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• pp.92-95
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• 2006

The global environment is deteriorating at an alarming rate despite of enhanced international environmental regulation. Many studies have been performed to reduce pollutants. Recently, phytoremediation, plant-based technology for the removal of toxic contaminants from soil, water, and air, has been receiving large attention. Arsenic-contaminated soil is one of the major pollutant sources fur drinking water. The fern brake (Pteris erotica) has been reported as a hyper-accumulate arsenic from soils. In this study, we investigated the arsenic absorption effect on sap flow inside xylem vessels of a fern brake. The synchrotron X-ray micro-imaging technique was employed to monitor flow inside the plant non-invasively. The captured phase-contrast X-ray images show both anatomy and transport of water inside the fern brake. The refilling process of water containing arsenic inside the xylem vessels of fern brake's leaves and stems was clearly observed. These results would provide important information needed fur understanding the mechanisms of accumulation, translocation, and transformation of toxic materials in plants.

• 방사선산업학회지
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• 제5권1호
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• pp.87-93
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• 2011

A laboratory experiment using a radioisotope was performed to analyze the characteristics of transport and diffusion of a pollutant released from industrial plants. A wave hydraulic model based on the similarity theory was constructed and used to reappear the tidal wave in the laboratory. Two-dimensional numerical models were used to reproduce the results of a wave hydraulic model. The measured and calculated concentrations were compared with the same conditions. As a result of the comparative study, the time of maximum concentration showed slight difference between them, but the values of maximum concentration were relatively well agreed.

• Wind and Structures
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• 제10권2호
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• pp.99-119
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• 2007

Estimations of wind flow over terrain are often needed for applications such as pollutant dispersion, transport safety or wind farm location. Whilst field studies offer very detailed information regarding the wind potential over a small region, the cost of instrumenting a natural fetch alone is prohibitive. Wind tunnels offer one alternative although wind tunnel simulations can suffer from scale effects and high costs as well. Computational Fluid Dynamics (CFD) offers a second alternative which is increasingly seen as a viable one by wind engineers. There are two issues associated with CFD however, that of accuracy of the predictions and set-up and simulation times. This paper aims to address the two issues by demonstrating, by way of an investigation of wind potential for the Askervein Hill, that a good level of accuracy can be obtained with CFD (10% for the speed up ratio) and that it is possible to automate the simulations in order to compute a full wind rose efficiently. The paper shows how a combination of script and session files can be written to drive and automate CFD simulations based on commercial software. It proposes a general methodology for the automation of CFD applied to the computation of wind flow over a region of interest.

• 대한토목학회논문집
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• 제28권5B호
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• pp.475-483
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• 2008

사고 등으로 인해 하천에 순간적으로 주입되는 오염물질의 2차원 이송-확산을 모의하기 위하여 SUPG법에 의한 2차원 유한요소 모형을 개발하고 주입된 질량과 모의 질량간의 오차를 산정하였다. 지배방정식으로부터 질량 오차 산정식을 유도하고 이를 간단한 예제에 적용하였다. 적용 예제로는 단순 직선수로에서 선원을 통한 질량주입과 일방향의 등질 유속장을 가지는 2차원 공간에서 점원을 통한 질량주입 문제를 가정하였으며, 기존의 Galerkin법과의 비교를 위하여 두가지 수치기법에 대한 모의 검증을 실시하였다. 검증결과 기존의 Galerkin법에 의한 모의 결과에 비하여 SUPG법을 통한 수치모형의 구성이 모의의 정확성뿐만 아니라 주입 질량의 보존에 있어서도 보다 정확한 방법임을 확인하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.405-405
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• 2022

본 연구는 주암조절지댐 유역의 강우 빛 비강우시츨 포함한 장기간의 유역유출 및 지하수 이동에 따른 유량분석과 오염물질 부하 유입특성을 분석함으로써 유역의 오염물질을 선제적으로 관리하고 조절지댐내의 수질을 효과적으로 관리하기 위해서 수행되었다. Hydrological Simulation Program - Fortran (HSPF) 모델을 적용하기 위하여 주암조절지댐 유역의 복잡한 지형과 기상조건 및 오염원 자료를 반영하고 수질관리 대책을 수립하는 데 적용하고자 하였다. 주암조절지댐 유역은 환경부의 소유역 구분을 고려하여 28개의 유역으로 세분화하고 티센망도를 고려해 3개의 그룹으로 재차 분류하였다. 기상 자료는 연구대상지역의 직접측정자료의 한계로 여수와 광양 기상청의 자료를 사용하였으며, 강우 자료 또한 소유역 그룹에 맞춰 입력 자료로 사용하였다. HSPF 모델의 보정은 유량 및 수질 (총질소 및 총인)에 대하여 2017 ~ 2021년의 모니터링 실측자료를 대상으로 수행되었다. 보정 결과는 R², RMSE로 평가하였고, 보정된 HSPF 모델을 바탕으로 유역별 유량 및 수질에 영향을 미치는 주요 인자를 분석하였다. 본 연구의 결과는 주암조절지댐의 수질을 예측할 수 있는 3차원 수리-수질 모델의 입력자료로 활용될 예정이며, 추후 기후변화 영향을 고려한 상류 유역의 수질관리 계획 수립에 기여할 것으로 기대된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제12권4호
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• pp.25-31
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• 2007

물질 간 상호작용이 위해도에 많은 영향을 미칠 수 있다는 것은 널리 알려져 있지만 이를 위해성평가에 적용할 수 있는 방안은 아직 미미한 실정이다. 본 연구에서는 p-xylene이 토양 내에 존재할 때, 대수층으로의 이동성이 극히 제한적인 benz[a]anthracene (BaA)의 지하수로의 이동성 증가를 확인하고 그 증가된 위해도를 산정하기 위하여, 지하 환경을 모사한 셀을 제작하여 실험을 수행하였으며, 이를 해석하는 간단한 물질이동 모델을 개발하였다. 셀 실험 결과 BaA의 이동성은, BaA와 p-xylene이 혼합물질로 동시에 존재하는 경우에, BaA만으로 오염되어 있는 경우보다 월등히 높았다. 후자의 경우는 강우에 의한 이동이 주요 이동기작이었으며 그 정도는 아주 미미하였다. Defined Time Steps (DTS)을 이용하여 개발된 오염물질 이동모델은 두 물질 모두 실험결과와 유사한 경향을 보이며 변하는 것을 확인하였으나, 더욱 정확한 예측을 위하여 모델의 수정, 보완작업이 계속되고 있으며 이는 다음 연구의 주제가 될 것이다. 실험실 규모의 셀 실험의 경우 모세관대가 물질이동에 중요한 역할을 하기 때문에 실험실 규모의 시뮬레이션에서는 모세관대 모듈을 적용하는 것이 보다 적합한 것으로 나타났다. 현장규모 오염에서의 모델링 결과를 토대로 위해도를 산정하고 비교한 결과, 지하수 섭취를 통한 BaA의 발암위해도는 NAPL이 존재할 때, 존재하지 않을 때보다, 약 15${\sim}$87배 크게 계산되었다. NAPL이 존재하지 않는 경우 BaA의 지중 이동속도는 매우 느리며, 실제 오염현장의 경우 이동 과정에서 물질분해가 일어나므로 NAPL의 존재 여부에 따른 실제 위해도 차이는 더 크게 발생할 것으로 예상된다.

• 수산해양기술연구
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• 제33권1호
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• pp.9-26
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• 1997

Stokes drift(SD) and Lagrangian discharge(LD) are important factors for analysis of flushing time, tidal exchange, solute transport and pollutant dispersion. The factors should be calculated using the approached method to flow phenomena. The aim of this paper re-examines the previous procedures for computing the SD and LD, and is to propose the new method approached to stratified flow field in the cross-section of coastal region, e.g. Masan Bay. The intensity of velocity near the bottom boundary layer(BBL) depends on the sea-bed irregularity in the coastal estuaries. So we calculated the depth mean velocity(DMV) considering that of BBL omitted in Kjerfve's calculation method. It revealed that BBL effect resulting in application of the bay acts largely on DMV in half more among 1l stations. The new expression of SD and LD per unit width in the cross-section using the developed DMV and proposed decomposition procedure of current were derived as follow : $$Q=u_0+\frac{1}{2}H_1{U_1cos(\varphi_h-\varphi_u)+U_3cos(\varphi_h-\varphi{ud})} LD ED SD$(Q_{skim}+Q_{sk2}) The third term, $Q_{sk2}$, on the right-hand of the equation is showed newly and arise from vertical oscillatory shear. According to the results applied in 3 cross-sections including 11 stations of the bay, the volume difference between proposed and previous SD was founded to be almost 2 times more at some stations. But their mean transport volumes over all stations are 18% less than the previous SD. Among two terms of SD, the flux of second term, $Q_{skim}$, is larger than third term, $Q_{sk2}$, in the main channel of cross-section, so that $Q_{skim}$ has a strong dependence on the tidal pumping, whereas third term is larger than second in the marginal channel. It means that $Q_{sk2}$ has trapping or shear effect more than tidal pumping phenomena. Maximum range of the fluctuation in LD is 40% as compared with the previous equations, but mean range of it is showed 11% at all stations, namely, small change. It mean that two components of SD interact as compensating flow. Therefore, the computation of SD and LD depend on decomposition procedure of velocity component in obtaining the volume transport of temporal and spacial flow through channels. The calculation of SD and LD proposed here can separate the shear effect from the previous SD component, so can be applied to non-uniform flow condition of cross-section, namely, baroclinic flow field.

• 한국대기환경학회지
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• 제34권2호
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• pp.321-330
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• 2018

Concentrations of the atmospheric radon and gaseous pollutants were measured at the Gosan site on Jeju Island from 2010 to 2015, in order to observe their time-series variation characteristics and examine the concentration change related to the airflow transport pathways. Based on the realtime monitoring of the atmospheric radon and gaseous pollutants, the daily mean concentrations of radon ($^{222}Rn$) and gaseous pollutants($SO_2$, CO, $O_3$, $NO_x$) were $2,400mBq\;m^{-3}$ and 1.3, 377.6, 41.1, 3.9 ppb, respectively. On monthly variations of radon, the mean concentration in October was the highest as $3,033mBq\;m^{-3}$, almost twice as that in July ($1,452mBq\;m^{-3}$). The diurnal variation of radon concentration shows bimodal curves at early morning (around 7 a.m.) and near midnight, whereas its lowest concentration was recorded at around 3 p.m. Several gaseous pollutants($SO_2$, CO, $NO_x$) showed a similar seasonal variation with radon concentration as high in winter and low in summer, whereas the $O_3$ concentrations had a bit different seasonal trend. According to the cluster back trajectory analysis, the frequencies of airflow pathways moving from continental North China, East China, Japan and the East Sea, the Korean Peninsula, and North Pacific Ocean routes were 36, 37, 10, 13, and 4%, respectively. When the airflow were moved to Jeju Island from continental China, the concentrations of radon and gaseous pollutants were relatively high. On the other hand, when the airflows were moved from North Pacific Ocean and East Sea, their concentrations were much lower than those from continental China.

• 한국환경보건학회지
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• 제31권5호
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• pp.349-359
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• 2005

In this study, we focused on the geographical and the meterological conditions, the atmospheric examination, the soil contents and compositions in order to establish cultural properties conservation plan in Gyeongju and its surroundings. Also, the transport route with environmental contaminants in Ulsan and Pohang was examined. The results could be summarized as follows ; Air pollutant and environmental contaminant was transported by two types of winds. One is induced by local winds, the other is induced by synoptic winds. Air contaminant transported from coastal regions to inland regions were associated with wind velocity. Gyeongju had good atmospheric conditions, i.e. $SO_2\;0.009{\sim}0.011ppm,\;CO\;0.6{\sim}0.8ppm,\;NO_2\;0.015{\sim}0.020ppm,\;O_3\;0.017{\sim}0.032ppm,\;PM_{10}\;46{\sim}62{\mu}g/m^3\;and\;Pb\;0.034{\sim}0.060{\mu}g/m^3$, which was below environmental air qualify standards and was little lower than those of Pohang and Ulsan. However, Ulsan and Pohang city are located on south-east coast and have many industrial facilities. Hence, air pollution problems become serious issues in Ulsan, Pohang, Busan, Daegu and other cities due to the emission of air pollutants from the various industrial facilities, incinerator and power plants, etc. The soil of Gyeongju had heavy metals conditions, i.e. $Cd\;0.01{\sim}0.08mg/kg,\;Cu\;N.D{\sim}2.39mg/kg,\;As\;N.D{\sim}0.07mg/kg,\;Hg\;N.D{\sim}0.15mg/kg,\;Pb\;0.49{\sim}1.39mg/kg,\;Cr^{+6}\;0.02{\sim}0.42mg/kg,\;Fe\;0.74{\sim}1.55mg/kg,\;Mn\;0.11{\sim}0.49mg/kg\;and\;Zn\;1.11{\sim}3.56mg/kg$. However, pH value of soil had range of $4.12{\sim}7.45$. The results showed that high pH concentration of soil could occur due to air pollution diffusion and environmental contaminant transport at Ulsan and Pohang city.

• 한국지하수토양환경학회지:지하수토양환경
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• 제14권6호
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• pp.53-64
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• 2009

습지는 다양한 생지화학적 반응기작을 통하여 폐수로부터 유입되는 유기오염물질을 완화/정화하는 지역으로 알려져있다. 본 연구에서는 습지에서 다양한 물질의 성상과 거동을 모의하기 위하여 수학적 모형을 개발하였다. 개발한 모형은 1차원 수직 포화 모형으로 이류, 수리학적 분산, 미생물에 의한 생분해, 산화/환원반응, 식생과 조수 등 외부환경의 영향을 고려하였다. 조수의 영향은 퇴적물 내 공극수의 흐름에 주기적인 변화를 일으키고, 계절에 따라 식생은 증발산과 뿌리로부터의 산소공급을 통해 흐름과 근권 내 산화/환원 환경에 영향을 미친다. 개발된 모형을 적용하여 습지퇴적물 내에 존재하는 관심물질의 공간적 및 시간적 분포 모의를 위한 가상의 수치실험을 수행하였다. 또한 대표적인 중금속 오염물질의 하나인 크롬의 습지퇴적물 내 성상과 거동을 모의하였다. 모의 결과는 식생 뿌리와 조수가 습지퇴적물 내 전자수용체, 환원물질, 중금속의 분포에 지대한 영향을 미칠 수 있음을 보여주었다.