Although many attempts have been made to solve the atmospheric diffusion equation, there are many limits that prevent both solving it and its application. The causes of these impediments are primarily due to both the partial differentiation term and the turbulence diffusion coefficient. In consideration of this dilemma, this study aims to discuss the methodology and cases of utilizing a passive air sampler to increase the applicability of atmospheric dispersion modeling. Passive air samplers do not require pumps or electric power, allowing us to achieve a high resolution of spatial distribution data at a low cost and with minimal effort. They are also used to validate and calibrate the results of dispersion modeling. Currently, passive air samplers are able to measure air pollutants, including SO2, NO2, O3, dust, asbestos, heavy metals, indoor HCHO, and CO2. Additionally, they can measure odorous substances such as NH3, H2S, and VOCs. In this paper, many cases for application were introduced for several purposes, such as classifying the VOCs’ emission characteristics, surveying spatial distribution, identifying sources of airborne or odorous pollutants, and so on. In conclusion, the validation and calibration cases for modeling results were discussed, which will be very beneficial for increasing the accuracy and reliability of modeling results.

해상으로 운송되는 위험유해물질 (HNS, Hazardous and Noxious Substance)은 6,000여종 이상으로 많은 종류를 포함하고 있으므로, 유출시 대응전략 수립을 위한 HNS 거동 및 위험반경 예측을 결정론적으로 제시하기 어렵다. HNS 거동예측에서는 예측의 신속성과 효율성을 고려하여 차이가 미미한 모든 종류의 HNS 특성을 모두 고려하는 대신에 거동에 크게 영향을 미칠 수 있는 특성들에 초점을 맞쳐 대표적인 거동예측 모델을 개발하여 적용할 필요가 있다. 본 연구에서는 HNS를 기체상, 액체상, 고체상 등 크게 3분류로 구분하고, 각각의 분류별 거동특성 모델링을 연구하였다. 물질 특성별 거동특성은 증기압, 용해도, 밀도 등을 고려하였으며, 각각의 변수에 따른 증발, 혼홥, 침강 등의 거동을 모델링하였다. 물질의 거동특성 모델링은 대기 해양 확산모델의 계산에서 대기중 확산, 수중 확산, 해저면 침적 등을 결정하는 과정으로 활용된다.

A three-dimensional Computational Fluid Dynamics (CFD) with the renormalization group (RNG) k-ε turbulence model was used to simulate flow patterns and corresponding dispersion of passive H₂S pollutant in urban area with complex terrains. The major emission sources of H₂S considered in this study include the sewage disposal plant and the leather waste water disposal plant located the northwest direction from the residential area. In order to describe the flow and dispersion characteristics of H₂S in the complex terrain, the terrain data in the modeling domain was processed as the input data for the CFD model, while the previous studies were conducted in flat terrains. The recirculating flow zone was formed behind the buildings, and the pollutant concentration in the zone was noticeably high because of limited ventilation. The velocity profile and ventilation rate along the height were calculated to identify the effective zone of weak flow and re-circulation by the buildings and complex terrains. According to this study, the CFD modeling was demonstrated to be highly effective to simulate the effect of buildings and complex terrains on the flow and dispersion of odors. Detailed studies are desirable to further validate the odor dispersion with measurements under more complex flow conditions.

Considering heat insulation and beautiful sight of construction, making use of exterior panels is increasing. Recently the exterior panels now are weak very much, and so in consequence of the weakness fire spreads rapidly. Compared with internal fire, external vertical fire spread rate goes rapidly and it is extensive in spread range, therefore it is dangerous very much. Accordingly, under present condition of poor standard of exterior panels, it is required to take measure to meet the appropriate situation. In this study, by making use of FDS(Fire Dynamic Simulation) program about external vertical fire of high rise building, fire behavior is searched by computer. It is important that realizing by computer fire modeling about external vertical fire must be included certainly in procedure of fire performance design in the future. In modeling program, FDS version 5 is available, and aluminium composite panel is applied in external panels. In this study, for realizing of actual fire condition, FDS is applied by details of fire scenarios considering influence of wind.

Odor emission effects of unit processes in 10 livestock farms and 3 manure treatment facilities in Y and I cities, Kyonggido, were simulated using puff model after the odor emission rates were measured. 2 degree level of odor intensity and 1 degree level of it were predicted by the puff model in the adjacent area of odor emission source and within the 8km radius range of it, respectively. As real time odor modelling system was operated at specific manure based fertilizer making facility located in Y city, the highest odor concentration was predicted at the entrance of that facility and relatively lower odor intensity was estimated at the place more or less be aparted from the emission sources. The higher odor intensity was evaluated at dawn and evening because the odor was accumulated in case of stable air condition.

In order to analyze the densification behaviour of stainless steel powder compacts during hot isostatic pressing (HIP) at elevated temperatures, a power-law creep constitutive model based on the plastic deformation theory for porous materials was applied to the densification. Various densification mechanisms including interparticle boundary diffusion, grain boundary diffusion and lattice diffusion mechanisms were incorporated in the constitutive model, as well. The power-law creep model in conjunction with various diffusion models was applied to the HIP process of 316L stainless steel powder compacts under 50 and 100 MPa at . The results of the calculations were verified using literature data. It could be found that the contribution of the diffusional mechanisms is not significant under the current process conditions.

To predict the oil spill dispersion phenomena in the ocean, the oil spill response model, which can be used for strategic purpose on the oil spill site, based on Lagrangian particle-tracking method was formulated and applied to the neighboring area with Pusan port where the oil spill incident occurred when the tanker ship No.1 Youil struck on a small rock near the Namhyungjeto on September 21, 1995. The real-time tidal currents to be required as input data of the oil spill model were obtained by the two-dimensional hydrodynamic model and the tide prediction model. Evaluation of tidal currents using observation data was successful. For wind data, other input data of oil spill model, observed data on the spot were used. To verify the oil spill model, the oil spill modelling results were compared with the field data obtained from the spill site. Compared the modelling results with the observation data, there exist some discrepancies but the general pattern of modelling results was similar to that of field observation. The modelling results on 7 days after spill occurred showed that the 40% of spilled oil is in floating, 36% in evaporated, 23% at shore, and 1% in out of boundary, respectively. According to the evaluation of weighting curves of effective components to the dispersion of oil, the winds make a 37% of contribution to the dispersion of oil, turbulent diffusion 39.5%, and tidal currents 23.5%, respectively. Provided the more accurate wind data are supported, more favorable results might be obtained.

To predict the oil-spill dispersion in marine waters, the oil-spill dispersion model based on Lagrangian particle-tracking method was developed and applied to Kwangyang and Jinju Bay. The tidal current movements to be required as input data of the oil-spill dispersion model were obtained by a two-dimensional numerical tidal model. Evaluation of tidal current movements using mean tide was successful. Modelling results were compared with the field data obtained at spill site. There were some descrepancies between modeling results and field data. However, the general pattern of modelling results was similar to that of field data. Provided the real-time tidal currents and more accurate wind data are supported, more favorable results can be obtained.

백두산은 지리적으로 전체 면적의 3분의 1이 북한에, 그 나머지 영역이 중국에 속해있다. 최근 백두산 화산분화의 다양한 전조현상들이 나타나고 있으나 백두산에서 실제 일어나고 있는 직접적인 분화 전조현상에 대한 관측 자료를 획득하는 것은 쉽지 않다. 또한 현재 분화 가능성이 대두되고 있는 백두산지역의 지질학적인 환경을 고려한 분화 시나리오에 대한 연구가 매우 부족한 상태이기 때문에 지질학적인 요인을 고려한 분화 시나리오의 작성과 화산재의 한반도 유입 가능성에 대한 신속한 대응을 위한 화산재 확산 조기경보 기술의 개발이 필요한 시점이다. 우리나라는 백두산으로부터 지리적으로 약 500km이상 떨어져 있고, 화산재 및 오염물질의 확산으로 인한 간접적인 피해 영향권 내에 있으므로, 백두산이 폭발적으로 분화한다면 백두산을 중심으로 한반도 주변의 기압배치에 따른 종관 기상장의 영향을 받아 화산 분출물들이 대기 중에서 이류, 확산, 침적됨으로 인해 지리적 위치에 따라 지역적으로 장·단기적인 피해가 발생할 가능성이 예상된다. 본 연구에서는 화산재의 이동 경로 및 침적두께를 추정할 수 있는 Fall3D모델을 사용하여 분화구 주변지역으로부터 한반도의 동쪽에 위치하고 있는 일본지역까지 시간에 따른 화산재 확산현상을 수치모의 하였다. 또한 백두산 분화를 가정한 대표사례일의 기상장을 계산하고 화산에서 분출되어진 총 분출량에 따라 구분되는 화산폭발지수에 따른 화산재의 확산 경로, PM10농도, 화산재의 침적두께를 계산, 분석하였다.

균열을 가진 콘크리트에서는 균열폭으로 유입되는 염화물 이온에 의해 열화가 가속화된다. 본 연구는 균열을 가진 콘크리트의 염화물 확산에 대한 모델링으로, 정상상태를 가정하여 1차원 (이방성) 및 2차원 (등방성) 균열 모델링을 수행하였다. 기존의 균열 모델링에서는 직사각형 균열패턴으로 모델링을 수행하였으나, 본 연구에서는 조도를 가진 쐐기형 형태로 균열을 모델링하였다. 검증을 위하여 1차원 유입에 대해서는 콘크리트 시편에 균열을 유입하여 염화물 영동실험을 수행하였으며, 2차원 유입에 대해서는 기존의 실험결과를 이용하여 검증을 수행하였다. 모든 경우에서 균열형태를 쐐기형으로 고려하여 염화물 확산성이 감소되었으며, 조도를 고려함으로서 합리적인 결과가 도출되었다. 특히 0.10~0.15의 조도계수를 고려할 때, 실험값에 가장 근접한 결과를 나타내었다.

In this paper, modeling on equivalent diffusion coefficient in cracked concrete is performed for 1-D (Anisotropic) and 2-D (Isotropic) diffusion based on steady state condition. In the previous research, rectangular shape of crack was considered but the shape was modified to wedge shape with torturity. For verification of the proposed model, crack is induced in concrete sample and migration test in steady state is performed for 1-D diffusion. For 2-D diffusion, previous test results are adopted for verification. Through considering wedge shape of torturity, diffusion coefficients in 1-D and 2-D diffusion are reduced, and the more reasonable results are evaluated.