• 한국환경과학회지
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• 제23권11호
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• pp.1889-1907
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• 2014

The characteristics of meteorological conditions related to changes in atmospheric environment on Jeju Island were investigated during recent years (2010-2012). This analysis was performed using the hourly observed data of meteorological variables (air temperature, wind speed and direction) and air pollutants ($O_3$, $PM_{10}$, $SO_2$, $NO_2$, and CO). Out of 5 pollutants, $O_3$ and $PM_{10}$ concentrations have frequently exceeded national environmental standards in the study area during the study period, with relatively higher concentrations than the others. The concentrations of $O_3$ and $PM_{10}$ in 2010 and 2011 were somewhat higher than those in 2012, and their highest concentrations were mostly observed in spring followed by fall. Nighttime $O_3$ concentrations (with relatively high concentration levels) were almost similar to its daytime concentrations, due to less $O_3$ titration by very low NO concentrations in the target area and in part to $O_3$ increase resulting from atmospheric transport processes. The transport effect related to the concentration variations of $O_3$ and $PM_{10}$ was also clarified in correlation between these pollutants and meteorological variables, e.g. the high exceedance frequency of concentration criteria with strong wind speed and the high concentrations with the westerly/northwesterly winds (e.g., transport from the polluted regions of China). The overall results of this study suggest that the changes in atmospheric environment in the study area were likely to be caused by the transport effect (horizontal and vertical) due to the meteorological conditions rather than the contribution of local emission sources.

• 대기
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• 제25권3호
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• pp.473-482
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• 2015

In this study, street canyons with a higher downwind building (so called, step-up street canyons) are considered for understanding characteristics of flow and reactive pollutants' dispersion as a basic step to understand the characteristics in wider urban areas. This study used a CFD_NIMR_SNU coupled to a chemistry module just including simple $NO_X-O_3$ photochemical reactions. First, flow characteristics are analyzed in step-up street canyons with four aspect ratios (0.33, 0.47, 0.6, 0.73) defined as ratios of upwind building heights to downwind building height. The CFD_NIMR_SNU reproduced very well the main features (that is, vortices in the street canyons) which appeared in the wind-tunnel experiment. Wind speed within the street canyons became weak as the aspect ratio increased, because volume of flow incoming over the upwind building decreased. For each step-up street canyon, chemistry transport model was integrated up to 3600 s with the time step of 0.5 s. The distribution patterns of $NO_X$ and $O_3$ were largely dependent on the mean flow patterns, however, $NO_X$ and $O_3$ concentrations were partly affected by photochemical reactions. $O_3$ concentration near the upwind lower region of the street canyons was much lower than background concentration, because there was much reduction in $O_3$ concentration due to NO titration there. Total amount of $NO_X$ in the street canyons increased with the aspect ratio, resulting from the decrease of mean wind intensity.

• 생물환경조절학회지
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• 제29권2호
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• pp.110-119
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• 2020

본 연구는 기존에 사용하여 왔고, 최근에 온습도의 정확도를 검증하였던 강제 흡출식 복사선 차폐장치(Aspirated Radiation Shield; ARS)를이용하여 모 기업(A 회사)에서 개발한 시스템의 성능을 개선하고, ARS 장치의 풍속이 온습도에 미치는 영향에 대해서도 시험적으로 검토하였다. 그 결과를 요약하면 다음과 같다. A 회사 제품의 시스템을 개선하기 전, A 회사 시스템의 온도는 ARS 장치로 측정한 온도보다 최대 10.2℃정도 높았고, 상대습도는 20.0%정도 낮게 나타났다. 시스템을 개선한 후, 노드 1, 2의 온도 및 상대습도는 거의 일치하는 것으로 나타났다. 개선 후의 노드 2와 ARS 장치로 측정한 온도간의 최고, 평균 및 최저온도를 포함한 온도편차는 각각 0.2~0.7℃정도로써 ARS 장치가 약간 낮거나 높게 나타나는 경향이 있었다. 상대습도의 경우, 일몰 직후 ARS 장치의 상대습도가 약 10.0%정도 높게 나타나는 경향이 있었지만, 그 이외에는 평균적으로 1.9%정도 ARS 장치가 약간 낮게 나타나는 경향이 있었다. 그리고 노드 1을 최소-중간 사이, 중간-최대 사이 및 최대로 설정한 경우, 노드 1, 2의 최고, 평균 및 최저온도를 포함한 편차는 각각 0.1~0.4℃, 0.0~0.2℃ 및 0.0~0.5℃정도였다. 그리고 노드 1의 3개 측점과 ARS 장치의 최고, 평균 및 최저온도를 포함한 편차는 각각 0.2~0.5℃, 0.1~2.2℃ 및 0.1~1.1℃정도의 범위로써 풍속의 크기에 따른 온도편차는 아주 미미한 것으로 나타났다. 또한 선행연구 및 본 연구의 결과를 종합하여 보면, 온도오차를 개선하기 위한 적정 풍속은 1.0~2.0m·s^-1 정도의 범위일 것으로 판단되었다.