• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.163-167
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• 1999

컴퓨터가 일반화됨에 따라 대기질 관리 및 연구 분야에서 수치모델 이용이 보편화되고 있다. 현재 사용되는 대기오염 수치모델의 종류는 매우 다양하며, 구동에 필요한 전산시스템의 규모도 다양하다. 연구용 및 대형 모델들은 활용 분야가 넓고 신뢰도가 높은 반면 대형 전산시스템과 고도의 전문 인력을 요구한다. 그러나, 국내 대부분의 대기질 관련 기관의 사용 가능한 전산시스템과 담당 인력을 고려할 때 대형 모델의 사용이 일반화되기에는 한계가 있다.(중략)

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1321-1329
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• 1989

본 논문에서는 성층화된 용액ㅇ네 수평방향으로 온도구배가 가해지는 경우에 있어서 두 부력인자의 상대적 크기에 따라 나타나는 유동형태와 그에 따른 온도, 농도 분포 및 열전달특성을 수치적으로 연구하고자 한다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.176-177
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• 2000

대도시의 국소지역인 도심지 도로변 양측은 빌딩에 의해 둘러싸여 있어 canyon으로 비유되어 street canyon이라고 하며 도로에 관한 선행연구는 도로변에 관한 것과 street canyon에 관한 것 그리고 두 경우를 전부 포함하는 경우로 분류할 수 있다. 도로변에 있어서 자동차 배출가스의 확산 예측에 관한 연구는 가우시안형 해석해 모형이 가장 많고 그 외 비가우시안형 해석해 모형, 반경험식 모형, 수치해 모형으로 분류되고 있다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.156-159
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• 1999

역사적으로 악명 높은 대기오염 사고인 뮤즈 계곡(Meuse valley; 1930년 벨기에), 도노라(Donora; 1948년 미국), 런던(London; 1952년 영국) 등의 사례에서 보듯이 대기오염은 기상 상황과 불가분의 관계를 맺고 있음은 주지의 사실이다. 대기오염 모델링에서도 사용된 기상 자료의 정확도가 대기오염 수치모의의 신뢰도를 좌우한다고 해도 과언이 아닌데, 기상 자료 중 바람장은 대기오염 물질의 이류 및 확산을, 온ㆍ습도장은 광화학 반응을 결정하는 중요한 요소이다.(중략)

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.345-346
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• 2022

본 논문에서는 유류오염사고 발생에 의해 지반 내에 오염물이 유출되었을 때, 오염물 확산방지를 목적으로 차수재의 차수성능 평가를 위한 수치해석을 수행하였다. 해석결과, 차수재의 차수효과에 의해 동일한 투수계수 및 관측위치 조건에서 오염물 접촉시간 경과에 따른 농도가 크게 감소한 것을 확인하였다.

• Journal of Korea Water Resources Association
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• v.45 no.2
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• pp.179-189
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• 2012

To simulate the transport of pollutant, a numeric model for the advection-diffusion equation with the decay term is developed. This is finite-difference model using the implicit method (with the weight factor ${\alpha}$) and Gauss-Seidel SOR(successive over-relaxation). This model is compared to the analytical solutions (of simpler dimensional or boundary conditions), and in the condition of Peclet number < 5~20, the result shows stable condition, and Crank-Nicolson method (${\alpha}$=0.5) shows the more accurate results than fully-implicit method (${\alpha}$=1). The mass of advection, diffusion and decay is calculated and the error of mass balance is less than 3%. This model can evaluate the 3-D concentrations of the advection-diffusion and decay problems, but this model uses only the finite-difference method with the fixd grid system, so it can be effectively used in the problems with small Peclet numbers like the pollutant transport in groundwater.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.4
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• pp.148-159
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• 2021

This study estimates the region of freshwater influence (ROFI) by Han River discharge in the Yeomha channel, Gyeonggi Bay. A 3-D numerical model, which is validated for reproducibility of variation in current velocity and salinity, is applied in Gyeonggi Bay. Distance of freshwater influence (DOFI) is defined as the distance from the entrance of Yeomha channel to the point where surface salinity is 28 psu. Model scenarios were constructed by dividing the Han River discharge into 10 categories (200~10,000 m³/s). The relation equation between freshwater discharge and DOFI was calculated based on performing a non-linear regression analysis. ROFI in Yeomha channel expands from the southern sea area of Ganghwa-do to the northern sea area of Yeongheung-do as the intensity of Han River discharge increases. The discharge and DOFI are a proportional relationship, and the increase rate of DOFI gradually decreases as discharge increases. Based on the relation equation calculated in this study, DOFI in the Yeomha channel can be estimated through the monthly mean Han River discharge. Accordingly, it will be possible to respond and predict problems related to damage to water quality and ecology due to rapid freshwater runoff.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.191-199
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• 1993

Diffusion of a steady horizontal line source in a turbulent shear flow is simulated by numerically solving a steady two-dimensional advective diffusion equation. The computational result is compared with the analytic solution for uniform velocity and diffusivity distributions over the depth. The analytic solution for constant velocity and diffusivity overestimates the degree of vertical mixing. The normalized equation indicates that friction factor is the only physical parameter that governs the vertical diffusion process. Sensitivities of the diffusion process to the friction factor and initial source position are analyzed. The rate of vertical mixing varies approximately as the square root of the friction factor. The optimal source position, which gives the most rapid mixing, lies above the mid-depth and moves toward the water surface as the friction factor increases.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.217-223
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• 1991

A capillary method was used to evaluate the properties of mass transfer process and diffusion coefficients in the gel food. Amaranth dye was selected as a diffusant material to visualize the degree of diffusion procedure easily. After contacting cylinder containing agar gel with amaramth dye solution for some hours, the gel was cut to five segments by 0.5 cm in length. The diffusant concentration from the segments were measured by the spectrophotometer at 523 nm. Prediction models for the diffused quantities in gel food were established by the regression program of SPSS package program. Generally, diffusion coefficient can be calculated by Fick's second law, however, it will be determined by using numerical analysis method more easily. Finally the diffusion coefficients in this research were calculated by arithmetic mean of the measured values. As raising gel agent concentration, the mean diffusion coefficient tended to decrease because the obstruction effect came to become significant.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.2
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• pp.99-110
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• 2016

When a riser is damaged, the oil spills to sea. Oil spills cause huge economic losses as well as a destruction of the marine environment. To reduce losses, it is needed to predict spilled oil volume from risers and the excursion of the oil. The present paper simulated the oil spill for a damaged riser using open source libraries, called Open-FOAM. To verify numerical methods, jet flow and Rayleigh-Taylor instability were simulated. The oil spill was simulated for various damaged leak size, spilled oil volume rates, damaged vertical locations of a riser, and current speeds. From results, the maximum excursion of the spilled oil at the certain time was predicted, and a forecasting model for various parameters was suggested.