Odor dispersion from road emissions were investigated using CFD (Computational Fluid Dynamics). The Shear Stress Transport k-ω model in FLUENT CFD code was used to simulate odor dispersion around the road. The two road configurations used in the study were at-grade and fill road. Experimental data from the wind tunnel obtained in a previous study was used to validate the numerical result of the road dispersion. Five validation metrics are used to obtain an overall and quantitative evaluation of the performance of Shear Stress Transport k-ω models: the fractional bias (FB), the geometric mean bias (MG), the normalized mean square error (NMSE), the geometric variance (VG), and the fraction of predictions within a factor of two of observations (FAC2). The results of the vertical concentration profile for neutral atmospheric show reasonable performance for all five metrics. Six atmospheric stability conditions were used to evaluate the stability effect of road emission dispersion. It was found that the stability category D case of at-grade decreased the non-dimensional surface odor concentration smaller 0.78~0.93 times than those of stability category A case, and that F case decreased 0.39~0.56 times smaller than those of stability category A case. It was also found that stability category D case of filled road decreased 0.84~0.92 times the non-dimensional surface odor concentration of category A case and stability category F case decreased 0.45~0.58 times compared with stability category A case.

Air pollution dispersion from rooftop emissions around hexahedron buildings was investigated using computational fluid dynamics (referred to hereafter as CFD). The Shear Stress Transport (referred to hereafter as SST) k-ω model in FLUENT CFD code was used to simulate the flow and pollution dispersion around the hexahedron buildings. The two buildings used in the study had the dimensions of H: L: W (where H = height, L = length, and W = width) with the ratios of 1:1:1 and 1:1:2. Experimental data from the wind tunnel obtained by a previous study was used to validate the numerical result of the hexahedron building. Five validation metrics are used to obtain an overall and quantitative evaluation of the performance of SST k-ω models: the fractional bias (FB), the geometric mean bias (MG), the normalized mean square errors (NMSE), the geometric variance (VG), and the factor of 2 of the observations (FAC2). The results of vertical concentration profile and longitudinal surface concentration of the 1:1:2 building illustrate the reasonable performance for all five metrics. However, the lateral concentration profile at X = 3H (where X is the distance from the source) shows poor performance for all of the metrics with the exception of NMSE, and the lateral concentration profile at X = 10H shows poor performance for FB and MG.

선박의 오염물질 배출에 대한 규제는 최근 IMO/MEPC(국제해사기구/해양환경보호위원회)를 통해서 진행 중이다. 선박오염원 에서 배출된 오염물질은 국지적인 요인에 의해서 연안지역을 비롯하여 육지로 확산될 수 있다. 인천과 같이 선박 배출 오염물질에 노출 되어 있는 항구 도시에서 선박오염원 조절은 연안지역의 대기질 관리정책을 효율적으로 고안하기 위해서 반드시 필요하다. 연안지역의 대기오염물질 중 선박에 의한 NOx와 SOx의 농도는 전체 NOx와 SOx 농도의 각각 14 %와 10 %를 차지한다(NIER, 2008). 연안도시지역의 대기질은 국지적인 순환에 의존하는 오염물질의 확산 경향과 선박의 수에 영향을 받는다. 선박오염원으로부터 배출된 오염물질의 확산 을 WRF(Weather Research and Forecasting model)의 기상장을 기초로 CALPUFF(California Puff model)를 사용하여 분석하였다. 그리고 연안도 시지역의 대기확산모델은 정박한 선박과 입·출항하는 선박으로 나누어 각각 점오염원과 선오염원으로 구분하여 모의하였다. 선박척수 82~84척을 기준으로 NOx의 총 평균 배출량은 입·출항시 각각 6.2 g/s, 6.8 g/s이었고, SOx의 총 평균 배출량은 입·출항시 각각 3.6 g/s, 5.1 g/s 이었다. 정박 중인 선박의 NOx와 SOx에 대한 총 평균 배출량은 각각 0.77 g/s, 1.93 g/s이었다. 육풍의 영향으로 인하여 인천항으로부터 내 륙으로 진행되는 오염물질의 수송이 억제되었고, 내륙의 SOx와 NOx 농도가 일시적으로 감소하는 원인이 되었다. 해풍에 의해 NOx와 SOx가 내륙으로 확산되었고, 내륙의 NOx와 SOx의 농도가 점차 증가하였다. 인천항과 인접한 지역의 오염물질의 농도는 해륙풍의 영향 보다 인천항에 정박 중인 선박오염원에 의한 영향이 더욱 크게 반영되었다. 본 연구는 연안도시지역의 대기질 정책고안과 배출기준을 정하는 것에 유용할 것으로 기대된다.

PURPOSES : This study presents a specific methodology for air dispersion analysis of urban areas methodology in accordance with urban planning and transport policy. METHODS: This study performed three alternatives including development density and public transit applying integrated urban model for the Delft city on Netherlands. Based on this result, the two types of air pollutant emissions(PM10, NOx) were calculated and analyzed the emission dispersion on that City. RESULTS: As a result, the quality of air near the City is better than that of current conditions showed that approximately from 2.1 to 7.9% according to alternatives. CONCLUSIONS: Air quality assessment in urban areas can be reasonably performed by applying a methodology when urban development and transport policy are considered.

PURPOSES : The objective of this study is to investigate the capability of the combined model of traffic simulation, emission and air dispersion models on the impact analysis of air quality of mobile sources such as vehicles. METHODS : The improvement of the quality of life brings about the increasing interest of the public environment. Many endeavors including the travel demand management, the application of the state-of-the-art ITS technologies, the promotion of eco-friendly vehicles have been tried in transportation area to reduce the modal emissions. Especially, it is expected that the increasing number of eco-friendly vehicles in the road network would be able to reduce the pipe-tail emissions tremendously. From this perspective, we have performed a study on the impact analysis of the popularization of the eco-friendly vehicle in the place of the fossil fuel energy powered vehicles on the surrounding air quality using the combined framework of microscopic traffic simulation, emission and air dispersion model. RESULTS : The combined model successfully captured the effect of moving to the eco-friendly vehicles on the air quality, and the results showed that the increasing usage of eco-friendly vehicles can improve the surrounding air quality tremendously and that the air dispersion model plays a crucial role in the investigation of the air quality change around the main corridor. CONCLUSIONS : This study demonstrated the capability of the combined model showing the spatio-tempral change of emission concentration.

Odorous compounds were monitored and dispersion modeling was conducted using AERMOD model. for Songtan Industrial Complex (SIC) located in Mogok-dong, Pyeongtaek city. The complex odor at the target area showed an average dilution ratio of 4.5 and low ammonia concentrations were observed (78.3 ppb). Sulfide, methyl iso-buthyl ketone, methyl ethyl ketone and styrene were not detected. The toluene concentration showed as 1233.3 ppb, which was the highest in the target compounds. The diffusion effect of odorous pollutants by wind was confirmed by descending order of concentration, inner-SIC (282 ppb) > downwind site (182 ppb) > upwind site (11.6 ppb). The results of the modeling demonstrated that the complex odors on the west and, south, north and east of the boundaries were dilution ratios of 10 24 and 20, respectively indicating the north and the east of SIC were more vulnerable to odor pollution than other regions.

건물군 내의 난류 유동에 의한 오염물질 확산을 LES 기법을 이용해 해석하였다. 본 연구의 동기는 복잡한 건물 내의 오염물질 확산을 효과적으로 예측하려는 노력에 기인한다. 결과적으로 확보될 예측 기술은 화학적으로 치명적인 재난을 예방하거나 기발생된 사고에 대한 빠른 대처를 가능케 할 것이다. 우선, 채널 내 난류 유동에 의한 농도 확산 및 단일 큐브 주위의 농도확산에 대한 타 연구 결과와의 비교를 통해 본 코드의 검증을 수행하였다. 그 다음에 도심 도로변의 배기가스에 의한 대기 오염을 모사하였다. Lagrangian dynamic subgrid-scale model이 유동장 및 농도장에 대한 난류 모델기법으로서 사용되었으며 log-law에 기반을 둔 유동장에 대한 벽모델이 바닥면과 건물 표면에 적용 되었다. 건물의 형상은 가상경계법을 이용해 직교좌표계에서 구현되었다.

The complex nature of low flow mixing in natural channels has been investigated using both laboratory experiments and the numerical solution of a proposed mathematical model that is based on a set of mass balance equations describing the mixing and mass exchange mechanisms. Laboratory experiments, which involved collection of channel geometry, hydraulic, and dye dispersion test data, were conducted in a model of four pool and riffle sequences in a 49-m long tilting flume. The experimental results show that flow over the model pool-riffle sequences is highly non-uniform. Concentration-time curves are significantly skewed with long tails. Comparison between measured and predicted concentration-time curves shows good agreement in the general shape, peak concentration and time to peak. The proposed model shows significant improvement over the conventional one-dimensional dispersion model in predicting natural mixing processes in open channels under low flow conditions through pools and riffles.