• Asian Journal of Atmospheric Environment
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• 제2권1호
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• pp.47-53
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• 2008

In this study, we analyzed how ozone pollution could be differently measured and how these different measures varied year to year and across the ten most populated cities in the United States, from 1980 to 2000. Although peak values of ozone concentration have been significantly reduced in most polluted U.S. cities for the last 20 years, the annual average values of ozone concentration have not been lowered as much as peak values. Ozone concentration data for each city shows a unique pattern of distribution, central tendency, and also there is a wide variation among different ozone measures. Two different cities with the same annual mean concentration of ozone can experience very different distributions of ozone concentration within a year. Ozone measures also show a wide margin of variability as they are estimated from different ozone monitoring sites within each city. Ozone pollution statistics can be largely varied depending on the choice of measures, monitoring sites, and averaging time period. EPA's new ozone standard of 0.08 ppm averaged over an eight-hour appears to be more stringent than the current maximum ozone standard of 0.12 ppm averaged over one hour.

• 한국환경과학회지
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• 제22권9호
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• pp.1213-1226
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• 2013

$PM_{10}$ concentration is related to the meteorological variables including to local and synoptic meteorology. In this study the $PM_{10}$ concentrations of Busan in 2007~2011 were analyzed and the days of yellow sand or rainfall which is more than 5 mm were excluded. The sections of $PM_{10}$ concentration were divided according to 10-quantiles, quartiles and 90-quantiles. The 90-quantiles of daily $PM_{10}$ concentration were selected as high concentration dates. In the high concentration dates the daily mean averaged cloudness, mean daily surface wind speed, daily mean surface pressure and PBL height were low and diurnal variation of surface pressure and daily maximum surface temperature were high. When the high $PM_{10}$ dates occurred, the west and south wind blew on the ground and the west wind blew strongly on the 850 hPa. So it seemed that long range transboundary air pollutants made effects on the high concentration dates. The cluster analysis using Hysplit model which is the backward trajectory was made on the high concentration dates. As a result, 3 clusters were extracted and on the short range transboundary cluster the daily mean relative humidity and cloudness were high and PBL height was low.

• 환경영향평가
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• 제2권1호
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• pp.57-63
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• 1993

An analysis for particle settling effects via of plume centerline tilted exponentially under the influence of panicle settling velocity is carried out for particle of $30{\mu}m$ diameter with $1g/cm^3$ density and 0.02m/s settling velocity corresponding to its particle characteristic according to various wind speeds, atmospheric stabilities. Characteristic analysis of surface concentration distribution simulated by Lagrangian model also are carried out under the influence of plume centerline tilted exponentially at 10m stack height emitted 200 particles per second. This study reveals that plume centerline at the nearby source is sharply tilted exponentially under the condition of stable, weakly wind speed, therefore the lower concentration at the nearby source, the higher concentration at the downwind distance far away from source than actual one is brought out, if not apply the effect of plume centerline tilted exponentially to diffusion Model.

• 한국기계가공학회지
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• 제16권3호
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• pp.88-93
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• 2017

In the present study, the ignition characteristics of liquid fuel were experimentally investigated. To quantify its ignitability as ignition characteristics, the minimum ignition energy (MIE) of liquid fuel was defined and measured under at the elevated oxygen concentrations and reduced atmospheric pressures which that are the most probable conditions likely to be encountered during operation of the space launch vehicle's operating process. The experimental results demonstrate that the measured MIE decreased with the increasing the oxygen concentration at given atmospheric pressures. When the atmospheric pressure was reduced from 1 atm to 0.2 atm at a fixed oxygen concentration, the measured MIE was found to vary with $P^{-2}$ but the lowest MIE was observed at 0.8 atm.

• Asian Journal of Atmospheric Environment
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• 제4권1호
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• pp.1-8
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• 2010

The effectiveness of the government regulation on tail-pipe emission for diesel vehicles issued in 2003 in Tokyo was evaluated in this study. Variations in annual average concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs associated with airborne particulate matter were investigated in connection with the variation in airborne elemental carbon (EC) concentration in downtown Tokyo, Japan in 2006-2007 and in 1997-1998. The annual average concentrations of EC, seven different PAHs, and 1-nitropyrene were found to have decreased significantly from 1997-1998 to 2006-2007. The most prominent decrease in atmospheric concentration was observed for 1-nitropyrene, which is a representative nitro-PAH originating from diesel vehicles. This indicated that the government control has worked to considerably reduce both atmospheric mutagens and airborne particulate matter. In contrast, the concentrations of two nitro-PAHs, 2-nitrofluoranthene and 2-nitropyrene, remained the same. These nitro-PAHs are known to be formed by atmospheric nitration of their parent PAHs, and this result suggested factors other than the concentration of parent PAHs and $NO_2$ affects the degree of atmospheric formation of nitro-PAHs.

• Asian Journal of Atmospheric Environment
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• 제11권1호
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• pp.33-36
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• 2017

China is suffering from severe air pollution especially fine $PM_{2.5}$ pollution. In 2015, the annual average $PM_{2.5}$ concentration of the 338 municipal cities was $50{\mu}g/m^3$, 78% cities at or above the prefectural level failed to comply with the $PM_{2.5}$ concentration standards. The $13^{th}$ Five-Year Plan for National Economic and Social Development set the goal that the annual average concentration of $PM_{2.5}$ in the municipal cities which failed to attain the ambient air quality standards shall be decreased by 18% by 2020 (CCCPC, 2016). In this study, an air pollution control scenario during the $13^{th}$ Five-Year Plan period was proposed and the $SO_2$, $NO_x$ and PM emission reductions in response to different measures in 31 provincial-level regions mainland China by 2020 were estimated. The air quality in the target year (2020) was simulated using the WRF-CMAQ model. The results showed that by 2020, the emissions of $SO_2$, $NO_x$ and primary PM in mainland China will be reduced by 4.19 million tons, 3.94 million tons and 4.41 million tons, a drop of 23%, 21% and 25% respectively compared with that in 2015, and the annual average concentration of $PM_{2.5}$ will decrease by 19%. Coal-fired power plant contributes the most pollutant emission reduction.

• 우주기술과 응용
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• 제4권3호
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• pp.220-231
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• 2024

이 연구는 헬륨풍선을 사용하여 한반도 전라북도 상공 대기층의 오존 밀도를 측정하고 높이 척도를 기반으로 대기 밀도의 변화를 분석하는 실험을 다룬다. 실험에서는 아두이노 Uno를 사용하여 데이터를 수집하고 MQ131 센서를 통해 오존 밀도를 측정했다. 또한 BMP280 센서를 사용하여 온도 및 대기 압력을 다양한 고도에서 측정했다. 실험 결과, 한반도 상공 대기의 높이 척도는 6,828.30 m로 나타났으며, 이를 기반으로 대기 밀도의 감소 패턴을 확인했다. 또한, 측정된 오존 수준의 그래프를 분석하여 8 km에서 9 km 고도 사이에서 오존 수준이 급격히 감소하는 현상이 관찰되었다. 이러한 결과들은 대기 환경 및 오존 밀도 변화를 이해하고 환경 모니터링에 중요한 정보를 제공할 수 있다.

• 한국대기환경학회지
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• 제7권3호
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• pp.156-168
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• 1991

The purpose of this paper is to develop a stochastic model for daily sulphur dioxide $(SO_2)$ concentrations prediction in urban area (Seoul). For this, the influence of the meteorological parameters on the $SO_2$ concentrations is investigated by a statistical analysis of the 24-hr averaged $SO_2$ levels of Seoul area during 1989 $\sim$ 1990. The annual fluctuations of the regression trend, periodicity and dependence of the daily concentration are also analyzed. Based on these, a nonlinear regression transfer function model for the prediction of daily $SO_2$ concentrations is derived. A statistical procedure for using the model to predict the concentration level is also proposed.

• 한국대기환경학회지
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• 제5권2호
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• pp.97-105
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• 1989

Recently, many studies on air quality prediction models have been performed to develope new ones. The purpose of the study is to obtain a method to predict $SO_2$ concentration simply in urban area using hour-to-hour meteorological data such as the wind speed, the incoming solar radiation, and the cloud coverages. The relationships between with speed and $SO_2$ concentrations are plotted in flgures. Predicted concentration curves are obtained for equation C=b/(1+au).

• 한국대기환경학회지
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• 제7권2호
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• pp.127-136
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• 1991

This paper is concerned with the development and application of a stochastic model for daily sulphur dioxide $(SO_2)$ concentrations in urban area (Seoul). For this, the characteristics of the regression trend, periodicity and dependence of the daily $SO_2$ concentration are investigated by a statistisical analysis of the daily average $SO_2$ values measured in Seoul area during 1989 $\sim$ 1990. Based on these, nonlinear regression time series model for the prediction of daily $SO_2$ concentrations is derived. A statistical procedure for using the model to predict the concentration level is also proposed.