• Geophysics and Geophysical Exploration
• /
• v.1 no.2
• /
• pp.87-91
• /
• 1998

Geophysical survey techniques, such as electromagnetic(EM), GPR, and electrical method, have been tested in the landfill area to evaluate the applicability of these methods to soil contamination measurement. The EM method has proven to be excellent on mapping the areal distribution of contaminants and the migration path for leachate. Since the field operation of EM technique is simple as well as fast, we think the EM method must be the first choice for these purposes. Electrical survey techniques have proven to be very effective on mapping sectional distribution of contaminants. Generally, the GPR method is very good on high resolution survey of shallow depth, and field data acquisition is simple, too. But the resistivity method gives better information on deep area, for example, deeper than the depth of 20 m.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.301-301
• /
• 2020

물은 보다 나은 삶을 살아가는데 있어 매우 중요한 자원이며, 안전하고 깨끗한 물을 공급받는 것은 국민 생활 영위에 반드시 필요한 부분이다. 국내 주요 수자원은 하천수를 통해 확보하고 있으며, 안전한 수자원 공급을 위해서는 하천관리를 통한 수질오염사고에 대비한 대책 수립이 필요하다. 국내에서는 페놀, 황산 등 독성오염물질 유출로 인한 수질오염사고가 발생한 바 있고, 그 피해액이 수백억에 달한다. 이러한 수질오염사고로 인한 피해액을 감소시키고 안전한 수자원 공급을 유지하기 위해서는 오염물질의 거동을 이해하고 예측하는 것이 매우 중요하다. 국내하천의 경우, 대부분 하폭 대비 수심비가 크기 때문에 오염물질이 2차원 혼합특성을 나타낸다. 따라서 본 연구에서는 하천 내 오염물질의 2차원적 혼합거동을 해석할 수 있는 수치모형을 개발하고자 하며, 현장에 적합한 해석기법을 검토하고 모형 개발 방향을 결정하고자 한다. 본 연구에서는 하천 내 수질오염사고 발생 시 신속하고 정확한 수질 분석 및 예측을 목표로 오염물질 혼합해석에 주로 활용되는 격자기반 모형과 입자추적 기반 모형의 프로토타입을 개발했다. 용존성 오염물질을 대상으로 격자 기반 및 입자 기반 혼합해석 모형을 개발했으며, 오염물질의 주입형태와 하천 내 유속 분포를 가정해 혼합해석을 수행했다. 격자 기반 모형의 경우, 경계조건과 분산계수의 결정이 필요하고 수렴/발산 문제로 인해 모형의 안정적 실행을 위한 조건 수립이 필요하다. 입자 기반 모형의 경우에도 입자 수에 따른 계산시간 개선이 필요하지만, 입력조건 결정이 간편하고 분산계수 입력이 필요 없어 신속한 모의조건 설정이 가능하다. 오염물질 혼합해석 모형 개발을 위한 해석기법 검토 결과, 신속한 수질 분석 및 예측 결과를 제공하기 위해서는 계산시간 개선을 전제로 모의조건 설정이 용이한 입자 기반 모형이 가장 적합한 것으로 판단된다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.70.2-70.2
• /
• 2015

현재 반도체 및 디스플레이이 공정 분야는 1 um 이상의 입자에서부터 10 nm이하 크기의 오염입자를 제어해야 한다. 현재 오염원인을 파악하기 위해서 사용하는 방법은 공정 완료 후 대상물(웨이퍼 및 글래스)을 CD-SEM (Critical Dimension Scanning Electron Microscope)와 같은 첨단 분석장비를 사용하여 사후 (Ex-situ) 진행하고 있다. 이러한 방법은 오염원이 이미 공정 대상물을 오염시키고 난 후 그 원인을 분석하는 방법으로 그 원인을 찾기가 어려울 뿐만 아니라, 최근 공정관리가 공정 진행 중(In-situ) 행해져야 하는 추세로 봤을 때 합당한 방법이라 할 수 없다. 이를 해결하기 위해 진공공정 중 레이저를 이용하여 측정하고자 하는 여러 시도들이 있었지만, 여전히 긍정적인 답변을 보여주지 못하고 있다. 본 발표에서 소개하는 PCDS (Particle Characteristic Diagonosis System)은 PBMS (Particle Beam Mass Spectrometer)와 SEM (Scanning Electron Microscope), 그리고 EDS (Energy Dispersive X-ray Spectroscopy)를 통합하여 만든 시스템으로 진공공정 중 (In-situ) 챔버 내부에서 발생하고 있는 입자의 크기 분포, 입자의 형상, 그리고 입자의 성분을 실시간으로 분석할 수 있는 방법을 제공한다. 이러한 방법 (PCDS)에 대한 개념과 원리, 그리고 현재까지 개발된 단계에서 얻어진 결과에 대해 소개할 것이다.

• Journal of Korea Water Resources Association
• /
• v.37 no.11
• /
• pp.889-896
• /
• 2004

The fractal advection-diffusion equation (ADE) is a generalization of the classical AdE in which the second-order derivative is replaced with a fractal order derivative. While the fractal ADE have been analyzed with a stochastic process In the Fourier and Laplace space so far, in this study a fractal ADE for describing solute transport in rivers is derived with a finite difference scheme in the real space. This derivation with a finite difference scheme gives the hint how the fractal derivative order and fractal diffusion coefficient can be estimated physically In contrast to the classical ADE, the fractal ADE is expected to be able to provide solutions that resemble the highly skewed and heavy-tailed time-concentration distribution curves of contaminant plumes observed in rivers.

• Korean Journal of Remote Sensing
• /
• v.36 no.2_1
• /
• pp.139-153
• /
• 2020

Using a computationalfluid dynamics(CFD) model, thisstudy evaluated the representativeness of an air quality monitoring system (AQMS) in an urban area and presented a methodology to determine the suitable AQMS locations for specific purposes. For this, we selected a 1.6 km × 1.6 km area around the Eunpyeong-gu AQMS (AQMS 111181) as a target area. We conducted simulationsfor two emission scenarios (scenario one: air pollutants transported from inflow boundaries, scenario two: air pollutants emitted from roads). Urban airflows were markedly influenced by mountainous terrain located in the northeast and southeast of the target area, and complicated airflow patterns occurred around the buildings. The distributions of air pollutants were dependent on the terrain (mountain) in scenario one, but the road location and building height in scenario 2. We evaluated whether the AQMS could represent the air quality in the target area based on the simulations for two scenarios. The concentrations simulated at the AQMS were similar in magnitude to the layer mean concentrations, which indicated good representativeness for the air quality in the target area. We also suggested which locations were suitable for different measurement purposes (hot spots, clean zones, average zones, shelter zones, equi-background zones).

• Journal of Environmental Impact Assessment
• /
• v.24 no.1
• /
• pp.87-98
• /
• 2015

Geochemical characteristics, water quality, $NO_3{^-}$ contamination and the origin of $NO_3{^-}$ were analyzed for the groundwater located at Ogcheon, Korea. The water qualities were weakly acidic to weakly alkalic and redox potentials indicated reduction condition. Compared to granitic rocks, metamorphic sedimentary rocks with intercalations of limestones and dolomites tended to be more effectively dissolved, resulting in higher pH and higher concentrations of dissolved ingredients. Contamination of heavy metals was not revealed. Geochemical reactions of carbonate rocks and influxes of artificial contamination ingredients seemed to simultaneously determine the geochemical characteristics and water qualities in the study area. From the results of ${\delta}^{15}N$ isotope analysis, the origin of $NO_3{^-}$ was estimated to be influenced dominantly by agricultural activities and human feces and urine.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.4 no.2
• /
• pp.144-154
• /
• 1999

Masan Bay is highly polluted by the discharge of large quantities of effluents from the industrial complex and domestic sewage of Masan City, Southeast Korea. Surface sediments from 9 stations were used for geochemical and foraminiferal analyses in order to investigate foraminiferal response to sedimentary pollution in the Bay. The heavy metal concentrations in sediments are relatively higher than those in Kyeonggi Bay and Daesan area, west coastal region of Korea. Zn, Cd, Pb, and As are more concentrated than in world average shale, indicating that the municipal and industrial effluents cause sediment contamination. Responses of benthic foraminifera to the sedimentary pollution effect document a degree of pollution in Masan Bay. The species number and diversity in Masan Bay had lower values than those in Gadeog Channel. In Masan Bay, agglutinated foraminifera are abundant and calcareous foraminiferal tests were frequently pyritized. Eggerella advena and Trochammina pacifica dominated at levels of pollution and could be opportunistic species. These data will provide a baseline for future assessments of environmental quality in Masan Bay.

• Geophysics and Geophysical Exploration
• /
• v.1 no.1
• /
• pp.57-63
• /
• 1998

The electrical resistivity method, one of old and widely used geophysical prospecting methods, has extended its scope to civil & environmental engineering areas. The electrical resistivity imaging technique was performed at the waste disposal site located in Junju to verify the applicability to the environmental engineering area. The dipole-dipole array, with the dipole spacing of 10 m, was applied along eight survey lines. The field data were obtained under the control of automatic acquisition softwares and topographic effects were corrected during processing stage. The processed resistivity images show that very low resistivity develops inside the disposal site and the distribution of low resistivity is exactly in accord with the boundary of the site except the river side. The depth of low resistivity zones is deeper toward the river side, which is interpreted that there is a high possibility for contaminants to be scattered to the river. From resistivity images, it was feasible to deduce the depth of waste disposal as well as the horizontal/vertical distribution of the contaminated zone, which proved the applicability of the electrical resistivity imaging technique to the environmental engineering area.

• Journal of Environmental Impact Assessment
• /
• v.31 no.4
• /
• pp.214-225
• /
• 2022

This study emphasized the soil of environmental impact assessment to devise measures to minimize the negative impact of project implementation on the environment. As a series of efforts for impact assessment procedures, a national inventory-based database was established for urban development projects, and three machine learning model performance evaluation as well as soil pollutant concentration distribution mapping were conducted. Here, nine soil pollutants were mapped to the metropolitan area of South Korea using the Random Forest model, which showed the best performance. The results of this study found that concentrations of Zn, F, and Cd were relatively concerned in Seoul, where urbanization is the most active. In addition, in the case of Hg and Cr6+, concentrations were detected below the standard, which was derived from a lack of pollutants such as industrial and industrial complexes that affect contents of heavy metals. A significant correlation between land cover and pollutants was inferred through the spatial distribution mapping of soil pollutants. Through this, it is expected that efficient soil management measures for minimizing soil pollution and planning decisions regarding the location of the project site can be established.

• Spatial Information Research
• /
• v.10 no.2
• /
• pp.263-273
• /
• 2002

This paper presents desirable water environmental management to a closed watershed. In order to obtain spatially distributed environmental information, GIS data have been used. Elevation data are used to extract stream channels automatically and to divide networks of a watershed. A Digital Elevation Model (DEM) has been developed, validated, and adopted to estimate the runoff of total nitrogen pollutant from watershed. This GIS-linked model can be applied effectively to the watersheds with many sub-streams, and for the estimation of pollutant runoff considering land use change.