• 한국대기환경학회지
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• 제27권2호
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• pp.168-180
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• 2011

The variation of the physicochemical properties of atmospheric aerosols in coexistence of the heavy Asian Dust and Haze observed from $15^{th}$ to $17^{th}$ March 2009 in Seoul was scrutinized through the mass and ion concentration observations and synoptic weather analysis. Although the ratio of PM1.0/PM10 was constant at 0.3 (which is typical during Asian Dust period in Korea) during the measurement period, both PM10 and PM1.0 mass concentrations were 3~6 times and 2~4 times higher than that of clear days, respectively. Water-soluble ion components accounted for 30~50% of PM10 and 50~70% of PM1.0 mass concentration. One of the secondary pollutants, $NO_3^-$ was found to be associated with $Ca^{2+}$ and $Na^+$ in coarse mode indicating that the aerosol derived from natural source was affected by anthropogenic pollutants. While the acidity of the aerosols increased in fine mode when the stagnation of weather patterns was the strongest (March $16^{th}$), the alkalinity increased in coarse mode when new air masses arrived with a southwestern wind after ending a period of stagnation (March $17^{th}$). In the selected case, SOR (Sulfur Oxidation Ratio, $nSO_4^{2-}/[nSO_4^{2-}+nSO_2]$) and NOR (Nitrogen Oxidation Ratio, $nNO_3^-/[nNO_3^-+nNO_2]$) values of ion components were higher than the general values during Asian Dust period. These results imply that dust aerosols could be mixed with pollutants transported from China even in heavy Asian Dust cases in Korea.

• 한국대기환경학회지
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• 제27권6호
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• pp.723-733
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• 2011

The ionic compositions were analyzed from the TSP samples collected at Gosan site in Jeju Island between 2000 and 2008, in order to examine the characteristics of atmospheric aerosols in accordance with the meteorological conditions. For the Asian Dust influence on the ionic compositions, the concentration ratios of $NH_4{^+}$, nss-${SO_4}^{2-}$, $NO_3{^-}$, and $K^+$ were about 1.2~2.3 during Asian Dust over Non-Asian Dust periods, noticeably that of nss-$Ca^{2+}$ was 6.8. Meanwhile the concentrations of nss-${SO_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ have increased as 1.8~4.4 times during the haze event periods, and 1.0~1.6 times during the fog and mist events. The ion balance has resulted that the anionic concentrations are relatively lower than the cationic concentrations, and the discrepancy appears more decidedly as a strong Asian Dust effect. The ammonium ion balance has shown that it exists as a mixture of $NH_4HSO_4$ and $(NH_4)_2SO_4$. The concentration ratios of nss-${SO_4}^{2-}/NO_3{^-}$ for Asian Dust, haze, fog-mist, and non-event periods were respectively 1.8, 5.9, 4.6, and 2.9, which were higher values compared to those in urban areas of China as well as other domestic regions. Especially, the high ratios of sulfur oxides could be presumed by the fact that the longrange transport of air pollutants from Asia continent might affect the atmospheric aerosols of Jeju Island.

• 한국대기환경학회지
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• 제34권4호
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• pp.567-587
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• 2018

A severe haze event occurred in October 2015 in Gwangju, Korea. In this study, the driving chemical species and the formation mechanisms of $PM_{2.5}$ pollution were investigated to better understand the haze event. Hourly concentrations of $PM_{2.5}$, organic and elemental carbon, water-soluble ions, and elemental constituents were measured at the air quality intensive monitoring station in Gwangju. The haze event occurred was attributed to a significant contribution (72.3%) of secondary inorganic species concentration to the $PM_{2.5}$, along with the contribution of organic aerosols that were strongly attributed to traffic emissions over the study site. MODIS images, weather charts, and air mass backward trajectories supported the significant impact of long-range transportation (LTP) of aerosol particles from northeastern China on haze formation over Gwangju in October 2015. The driving factor for the haze formation was stagnant atmospheric flows around the Korean peninsula, and high relative humidity (RH) promoted the haze formation at the site. Under the high RH conditions, $SO{_4}^{2-}$ and $NO_3{^-}$ were mainly produced through the heterogenous aqueous-phase reactions of $SO_2$ and $NO_2$, respectively. Moreover, hourly $O_3$ concentration during the study period was highly elevated, with hourly peaks ranging from 79 to 95ppb, suggesting that photochemical reaction was a possible formation process of secondary aerosols. Over the $PM_{2.5}$ pollution, behavior and formation of secondary ionic species varied with the difference in the impact of LTP. Prior to October 19 when the influence of LTP was low, increasing rate in $NO_3{^-}$ was greater than that in $NO_2$, but both $SO_2$ and $SO{_4}^{2-}$ had similar increasing rates. While, after October 20 when the impact of haze by LTP was significant, $SO{_4}^{2-}$ and $NO_3{^-}$ concentrations increased significantly more than their gaseous precursors, but with greater increasing rate of $NO_3{^-}$. These results suggest the enhanced secondary transformation of $SO_2$ and $NO_2$ during the haze event. Overall, the result from the study suggests that control of anthropogenic combustion sources including vehicle emissions is needed to reduce the high levels of nitrogen oxide and $NO_3{^-}$ and the high $PM_{2.5}$ pollution occurred over fall season in Gwangju.

• 한국대기환경학회지
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• 제31권3호
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• pp.223-238
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• 2015

The $PM_{2.1}$ was collected by LVCI (low volume cascade impactor) during Group-A Period (September 1990 to December 2012) and the $PM_{2.5}$ was collected by HVAS (high volume air sampler) during Group-B Period (September 2009 to April 2012) at Kyung Hee University, Global Campus located on the boarder of Yongin and Suwon. The 8 water-soluble ions ($Na^+$, $NH_4{^+}$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, $ NO_3{^-}$, and $SO_4{^{2-}}$) were analyzed by IC, and the 14 inorganic elements (Al, Mn, Si, Fe, Cu, Pb, Cr, Ni, V, Cd, Ba, Zn, Ti, Ag) were analyzed by XRF and ICP-AES after performing proper pre-treatments of each sample filter. The average total mass fractions of $SO_4{^{2-}}$, $NO_3{^-}$, and $NH_4{^+}$+ to $PM_{2.5}$ samples during Group-B Period were 0.39 in normal days, 0.44 in haze days, and 0.27 in Asian dust days, respectively; however, the average total mass fractions of Al, Fe, and Si to $PM_{2.5}$ mass were 0.043 in normal days, 0.021 in haze days, and 0.036 in Asian dust days, respectively. Especially the concentration of Pb was significantly decreased during Group-B Period rather than during Group-A Period, while Cr and Ni was increased during Group-B Period. In this study, we intensively compared the annual and seasonal patterns of major chemical species among normal days, haze days, and Asian dust days. Further we developed mass fraction profiles by collecting episode cases of haze days and Asian dust days, which were consisting of 22 chemical species. Those profiles are considered to be useful when applying various receptor models and establishing air quality management plans near future.

• 분석과학
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• 제27권4호
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• pp.213-222
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• 2014

국내 배경지역인 제주도 고산측정소에서 2012~2013년에 대기 미세먼지를 채취하여 분석한 결과로부터 연무와 비현상일의 조성특성을 조사하였다. 연무 시 $nss-SO_4{^{2-}}$, $NO_3{^-}$, $NH_4{^+}$ 농도는 비현상일에 비해 조대입자에서 2.1~3.7배, 미세입자에서 3.1~6.5배로 미세입자에서 더 높게 증가하였고, 특히 $NO_3{^-}$ 농도가 미세입자에서 6.5배 상승하였다. 원소성분들 중에는 S, Zn, Pb, K 등이 비현상일보다 조대입자에서 3.0~5.6배, 미세입자에서 3.2~7.7배 증가하나 Al, Fe, Ca 등은 대부분 조대입자에서 농도가 크게 증가하는 경향을 보였다. 역궤적 분석 결과 연무 시 $nss-SO_4{^{2-}}$, $NO_3{^-}$ 농도는 중국으로부터 유입되었을 때 더 높은 농도를 나타내었고, 특히 기류가 중국남부를 통과했을 때 $NO_3{^-}$ 농도가 더 크게 상승하는 경향을 보였다. 또 $NO_3{^-}/nss-SO_4{^{2-}}$ 농도비는 중국에서 기류가 이동했을 때 조대입자에서 상대적으로 높은 비율을 보이나 미세입자에서는 오히려 한반도를 통과했을 때 더 높은 성분비를 나타내었다.

• 한국대기환경학회지
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• 제32권3호
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• pp.329-341
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• 2016

Pohang is a well-known industrial city in Korea with a large steel-industrial complexes. The biggest environmental issue in the city is associated with fine particulate matter (hereinafter, $PM_{10}$). The concentration of $PM_{10}$ is generally dependent on the local emission sources and meteorological conditions. Iron and steel industrial complexes are likely serious pollution sources of $PM_{10}$ in Pohang. In this study, daily $PM_{10}$ data from a large database from the year of 2000 to 2012 were statistically analyzed, together with meteorological data. The average concentrations of $PM_{10}$ were evaluated according to the frequency of Asian dust, haze, mist, and fog. The number of days exceeding short-term standard for $PM_{10}$ were also examined, taking into consideration of weather conditions. It was found that the concentration of $PM_{10}$ was reduced about 18% to 26% because of precipitation. In addition, the effects of wind direction and wind speed on the $PM_{10}$ concentrations were investigated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.5039-5055
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• 2018

The quality of natural outdoor images captured by visible camera sensors is usually degraded by the haze present in the atmosphere. In this paper, a fast image dehazing method based on visible image and near-infrared fusion is proposed. In the proposed method, a visible and a near-infrared (NIR) image of the same scene is fused based on the dual-tree complex wavelet transform (DT-CWT) to generate a dehazed color image. The color of the fusion image is regulated through haze concentration estimated by dark channel prior (DCP). The experiment results demonstrate that the proposed method outperforms the conventional dehazing methods and effectively solves the color distortion problem in the dehazing process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.594-594
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• 2012

Al doped ZnO (AZO) thin films were deposited on textured glass substrate by magnetron sputtering method. Also, AZO films on textured glass were etched by hydrochloric acid (HCl). Average thickness of etched AZO films are 90 nm. We observed morphology of AZO film by AFM with various etchant concentration and etching time. Etched AZO films have low resistivity and high haze. The surface RMS roughness of AZO film was increased from 53.8 nm to 84.5 nm. The haze ratio was also enhanced in above 700 nm of wavelength due to light trapping effect was increased by rough AZO surface. The etched AZO films on textured glass are applicable to fabricate solar cell.

• 한국대기환경학회지
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• 제29권3호
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• pp.237-250
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• 2013

At Gosan ABC superstation in Jeju Island, we measured organic carbon (OC) and elemental carbon (EC) in $PM_{2.5}$ from October 2009 to June 2010 using a Sunset Laboratory Model-4 Semi-Continuous OC/EC Field Analyzer. It employs TOT (Thermal-Optical-Transmittance) method with NIOSH 5040 protocol and enables to continuously monitor OC and EC concentrations with 1-hour time resolution. The mean values of OC and EC for the entire period of measurements were $2.1{\pm}1.4{\mu}g/m^3$ and $0.7{\pm}0.6{\mu}g/m^3$, respectively. The OC/EC ratio was 3 and EC accounted $25{\pm}2.1%$ of total carbon (TC, TC=OC+EC). Although OC and EC showed similar trend in seasonal variation, the ratio of OC to EC was the highest in early summer when temperature was the highest and the air was affected by biomass burning in the southern part of China. In winter, the high OC and EC concentrations were likely influenced by increased coal combustion from residential heating. The high OC and EC concentrations were observed during events such as haze, dust, and the combination of the two. During the haze events, OC and EC were enhanced with increase in $PM_{10}$, $PM_{2.5}$, $SO_2$, and $NO_2$ with broad maxima. When dust occurred, both OC and EC started decreasing after reaching their maxima a couple of hours before $PM_{10}$ maximum. The peak separation of carbonaceous species and aerosol masses with time was more noticeable when haze event was followed by dust plume. These results confirm that OC and EC are key components of haze occurring in the study region.

• 한국대기환경학회지
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• 제31권3호
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• pp.209-222
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• 2015

Fine and coarse PM had been collected by LVCI (low volume cascade impactor) and HVAS (high volume air sampler) during January 1989 to April 2012 at Kyung Hee University, Global Campus located on the boarder of Yongin and Suwon. The database of PM mass concentration was constructed and then intensively and extensively investigated to understand monthly, seasonal, and annual patterns of each PM behavior. Especially the study separated all the PM data into the 5 Period Zones, which were classified on the basis of social, political, and environmental issues that might be influencing local ambient air quality during the monitoring period. The overall $PM_{10}$ level had been continuously decreased until 2005 and after then was staggering due to rapidly increasing $PM_{2.5}$ level in $PM_{10}$. The annual average of $PM_{2.5}$ concentration varied from $34.3{\mu}g/m^3$ to $59.0{\mu}g/m^3$, which were much higher than the 2015 ambient air quality standard. The $PM_{2.5}$ level was strongly associated with haze events, while both $PM_{10}$ and $PM_{2.5}$ levels were associated with Yellow storm events. Daily concentrations of $PM_{2.5}$ were ranged $13.1{\sim}212.9{\mu}g/m^3$ in haze days and $33.6{\sim}124.6{\mu}g/m^3$ in Asian dust days. The study also intensively investigated annual and seasonal patterns of $PM_{2.5}/PM_{10}$ ratios.