본 논문은 3차원 축대칭 몰수체에 대해 소스 코드가 공개된 OpenFOAM 4.0을 이용하여 첫 번째 격자의 높이와 레이놀즈 수에 따른 마찰저항 변화에 대해 연구하였다. 마찰저항 계산을 위해 경계조건, 수치조건을 정립하였다. 축대칭 물체의 3차원 효과로 인해 거칠 기가 매우 작은 12 μΜ에서도 부드러운 표면과 비교해 마찰저항이 다르게 계산되었다. 레이놀즈 수가 커질수록 경계층의 두께 증가가 감소되었으며 이로 인해 마찰저항의 증가량이 감소되었다. 첫 번째 격자의 크기인 y+에 대한 영향에 대해서도 검토하였다. 첫 번째 격자가 log layer에 위치하고 있지 않으면 마찰저항과 표면의 전단력이 과도하게 예측되는 것을 확인하였다. 이는 경계층이 두껍게 예측되어 난류 에너지가 과도하게 예측되었기 때문으로 판단된다. 표면의 거칠기가 커질수록 경계층이 두꺼워지고 표면의 난류에너지가 증가되는 것을 확인하였다. 마찰저항을 정확하게 예측하기 위해서는 y+ 값, 거칠기 및 벽함수가 적절한 영역에 위치해야 함을 알 수 있었다.

This study aims to identify the impacts of air quality in the Korean Peninsula according to the China's environmental policies in preparation of the Beijing 2008 Olympic Games. The measurement of emission variations in China, aircraft measurement, and modelling were carried out. The reduction measures in Beijing, China and its emission changes resulted in 30~65% in decrease out of the total emissions within the Beijing region, whereas when it comes to the whole nation of China, the reduction rate was about 4~9%. Comparing the concentration of the air pollutants in Seoul and Ganghwa in August 2008 during around the period of Beijing Olympic Games with one in 2004~2007 showed that the SO2 concentrations in the past was above 5ppb, while the concentration in the 2008 olympic period was 4ppb and below. The NOx at the Seokmori site in Ganghwa tended to be lower in concentration in 2008 than in between 2004~2007. As for O3 and PM2.5, the concentration tended to be rather low since August 11. The air current track that showed during the period of aircraft measurement presented to be flowed into Korea through the Northeast part of China and the coast of Bohai Bay, while the concentrations of SO2, NOx, and O3 over the west sea on August 20 and 24 were 0.54 (0.28ppb), 0.86 (1.84ppb), and 54.0 (41.5ppb) respectively, similar or lower than the ones measured in the past in the similar current patterns. The modelling result showed similar patterns to the data of aircraft measurement, in particular in SO2. Overall, the reduction measures in Beijing, China affected directly and indirectly the air quality in the Korean peninsular, but the impact was not significant as it was momentary and limited to the intended area.

Aircraft Measurements of gaseous pollutants(SO2, NOx and O3) in the Yellow Sea area, were carried out on 1997-2007. Main measurement site in 124°-127°E, 35°-37°N (in the Yellow Sea), have been done along the paths classified vertically and zonally. To understand how the air stream affects Long-range transboundary pollutants in Northease Asia (LTP), the tracks of pollutants in northeast Asia have been analyzed by dividing into 6 different regions(regions I-V and L). Compared with Korea's local sources and western north Pacific influenced by the Yellow Sea, when the air stream from region Ⅱ is dominant, the SO2 concentrations are 3-6times higher. In region Ⅱ and Ⅲ, SO2 concentrations are represented highest at 25.0 and 14.7 ppb, respectively. However, in other regions, SO2 concentration was recorderd the highest at 1.1-3.8 ppb, which is 7-15% higher then the highest one over the region Ⅱ and Ⅲ. During 1997-2007, the mean amount of incoming pollutants is 0.162 ton/km·hr exceeding about 5-times mean amount of outgoing pollutants over the West Sea. During the observed period, the amount of incoming and outgoing SO2 over the Yellow Sea is the highest in winter, at 0.224 ton/(km·hr) and 0.120 ton/(km·hr), respectively.