• Journal of Environmental Science International
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• v.31 no.7
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• pp.637-652
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• 2022

In this study, the contributions of emissions (foreign and domestic) and atmospheric physical and chemical processes to PM_2.5 concentrations were evaluated during a high PM_2.5 episode (March 24-26, 2018) observed on the Jeju Island in the spring of 2018. These analyses were performed using the community multi-scale air quality (CMAQ) modeling system using the brute-force method and integrated process rate (IPR) analysis, respectively. The contributions of domestic emissions from South Korea (41-45%) to PM_2.5 on the Jeju Island were lower than those (81-89%) of long-range transport (LRT) from China. The substantial contribution of LRT was also confirmed in conjunction with the air mass trajectory analysis, indicating that the frequency of airflow from China (58-62% of all trajectories) was higher than from other regions (28-32%) (e.g., South Korea). These results imply that compared to domestic emissions, emissions from China have a stronger impact than domestic emissions on the high PM_2.5 concentrations in the study area. From the IPR analysis, horizontal transport contributed substantially to PM_2.5 concentrations were dominant in most of the areas of the Jeju Island during the high PM_2.5 episode, while the aerosol process and vertical transport in the southern areas largely contributed to higher PM_2.5 concentrations.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.82-99
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• 2016

This study was carried out to understand the regional contribution of Particulate Matter (PM) emissions from East Asia ($82^{\circ}{\sim}149^{\circ}E$, $18^{\circ}{\sim}53^{\circ}N$) to Seoul during high concentration period in February 2014. The Community Multi-scale Air Quality (CMAQ) version 5.0.2 with Decoupled Direct Method (DDM) was used to analyze levels of contributions over Seoul. In order to validate model performance of the CMAQ, predicted PM and its chemical species concentrations were compared to observations in China and Seoul. Model predictions could depict the daily and hourly variations of observed PM. The calculated PM concentrations, however, had a tendency of underestimation. The discrepancies are due to uncertainties of meteorological data, emission inventories and CMAQ model itself. The high PM concentration in Seoul was induced by stationary anticyclone over the West Coast of Korea during 24 to 27 February. The DDM in CMAQ was used to analyze the contributions of emissions from East Asia on Seoul during this PM episode. $PM_{10}$ concentration in Seoul is contributed by 39.77%~53.19% from China industrial and urban region, 15.37%~37.10% from South Korea, and 9.03%~18.05% North Korea. These indicate that $PM_{10}$ concentrations in Seoul during the episode period are dominated by long-range transport from China region as well as domestic sources. It was also found that the largest contribution region in China were Shandong peninsula during the PM event period.

• Particle and aerosol research
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• v.7 no.2
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• pp.49-57
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• 2011

High concentration of PM10 was reported on late July, 2005 in Seoul along with high particulate ion concentrations in PM2.5. To identify the reason for the severe air pollution episode, time series analysis of the PM10 concentration in the monitoring sites over Korea, wind sector analysis, trend analysis of the ion concentrations, and air mass trajectory analysis were carried out. It was found that the episode could be classified into two separate periods; first one between July 22 and 27 and second one between July 28 and 31. During the first period, the PM10 concentrations at Seoul were in good correlation with the PM10 concentration three hours before at Chuncheon. Trajectory analysis showed that air mass moved from north and turned to west at Kangwon province to Seoul. The concentrations of PM10 mass and ionic species were lower than the second period. During the second period, air mass moved from northern China to Seoul directly and the PM10 concentrations all over the mid-Korean peninsula showed the same trend. These observations suggest that the air pollution during the second period was affected by direct transport of air pollutants from northern China. Thus, the air quality at Seoul during both periods were influenced by long-range transport from outside rather than by local sources, but with different transport patterns.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.3
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• pp.300-309
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• 2008

Variations in PM10 concentration between 2000 and 2005 from 84 urban air monitoring stations operated by the government were analyzed. The K-means cluster analysis was attempted using annual average and the 99th percentile of daily averages as parameters. The results obtained by excluding Asian dust episode days were compared with those obtained by using all available data. In any cases, the cluster with the highest mean concentration was mostly composed of stations in Seoul and Gyeonggi. Annual average of the cluster with the highest mean concentration showed a distinct decreasing trend, but that excluding Asian dust episode days did not show such a trend. Without Asian dust episode days high concentrations of monthly averages in March and April were also not observed. The effect of Asian dust was more pronounced in the 99th percentile of daily averages. The 99th percentile of daily averages of the cluster with the highest mean concentration was the highest in June following downs in April and May.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2007.10a
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• pp.405-406
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• 2007

• Journal of Environmental Science International
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• v.30 no.10
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• pp.789-802
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• 2021

This study analyzed the characteristics of high PM_2.5 episodes that meets the concentration criteria of Emergency Reduction Measures Plan (ERMP) in Busan during the 2015-2020, and compared with those in Seoul. As a first step, the CAPSS-2017 emission data was employed to analyze the emission differences between Busan and Seoul, and pointed out that Busan emission included the dominance of ship emissions (37.7%) among total PM_2.5 city emissions, whereas fugitive PM_2.5 emission was the highest in Seoul. These emission characteristics are indicating that the controlling action plan should be uniquely applied to cope with ERMP in each region. We selected extremely high PM_2.5 episode days that meet the criteria of ERMP levels. In Busan, Ulsan, and Gyeongnam region, 15, 16, and 8 days of extremely high PM_2.5 cases were found, respectively, whereas Seoul showed approximately doubling of occurrences with 37 cases. However, the occurrences in summer season indicated big differences between two cities: the proportion of summer-season occurrence was 13-25% in Busan, whereas no single case have occurred in Seoul. This is suggesting the needs of comprehensive summer emission reduction plan with focusing on sulfur reduction to effectively cope with the ERMP levels in summer in the southeastern region, including Busan.

• Journal of Chest Surgery
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• v.52 no.2
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• pp.85-90
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• 2019

Background: Variation exists in the initial treatment for the first episode of primary spontaneous pneumothorax (PSP), and no definitive consensus exists due to a lack of high-quality evidence. This study examined the outcomes of needle aspiration and closed thoracostomy in first episodes of PSP requiring intervention. Methods: This study was a randomized, prospective, single-center trial conducted between December 2015 and August 2016. Patients of all ages with a documented first episode of PSP who were unilaterally affected, hemodynamically stable, and had a pneumothorax measuring over 25% in size were included. Patients with underlying lung disease, severe comorbidities, bilateral pneumothorax, tension pneumothorax, recurrent pneumothorax, traumatic pneumothorax, and pregnancy were excluded. Patients were randomly assigned to the needle aspiration or closed thoracostomy group using a random number table. Results: Forty patients with a first episode of PSP were recruited, and 21 and 19 patients were included in the needle aspiration group and the closed thoracostomy group, respectively. The hospital stay of each group was $2.1{\pm}1.8days$ and $5.4{\pm}3.6days$, respectively (p<0.01). However, no significant differences were found in the success rate of initial treatment or the 1-month and 1-year recurrence rates. Conclusion: Needle aspiration is a favorable initial treatment in patients experiencing a first episode of PSP.

• Particle and aerosol research
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• v.15 no.3
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• pp.91-104
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• 2019

In this study, hourly measurements of $PM_{2.5}$ and its major chemical constituents such as organic and elemental carbon (OC and EC), and ionic species were made between January 15 and February 10, 2018 at the air pollution intensive monitering station in Gwangju. In addition, 24-hr integrated $PM_{2.5}$ samples were collected at the same site and analyzed for OC, EC, water-soluble OC (WSOC), humic-like substance (HULIS), and ionic species. Over the whole study period, the organic aerosols (=$1.6{\times}OC$) and $NO_3{^-}$ concentrations contributed 26.6% and 21.0% to $PM_{2.5}$, respectively. OC and EC concentrations were mainly attributed to traffic emissions with some contribution from biomass burning emissions. Moreover, strong correlations of OC with WSOC, HULIS, and $NO_3{^-}$ suggest that some of the organic aerosols were likely formed through atmospheric oxidation processes of hydrocarbon compounds from traffic emissions. For the period between January 18 and 22 when $PM_{2.5}$ pollution episode occurred, concentrations of three secondary ionic species ($=SO{_4}^{2-}+NO_3{^-}+NH_4{^+}$) and organic matter contributed on average 50.8 and 20.1% of $PM_{2.5}$, respectively, with the highest contribution from $NO_3{^-}$. Synoptic charts, air mass backward trajectories, and local meteorological conditions supported that high $PM_{2.5}$ pollution was resulted from long-range transport of haze particles lingering over northeastern China, accumulation of local emissions, and local production of secondary aerosols. During the $PM_{2.5}$ pollution episode, enhanced $SO{_4}^{2-}$ was more due to the long-range transport of aerosol particles from China rather than local secondary production from $SO_2$. Increasing rate in $NO_3{^-}$ was substantially greater than $NO_2$ and $SO{_4}^{2-}$ increasing rates, suggesting that the increased concentration of $NO_3{^-}$ during the pollution episode was attributed to enhanced formation of local $NO_3{^-}$ through heterogenous reactions of $NO_2$, rather than impact by long-range transportation from China.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.1029-1041
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• 2013

In this study, eight episode days of high-concentration $PM_{10}$ occurrences in the Gimhae region between 2006 and 2011 were analyzed. Most of them appeared in winter and the highest concentration was observed around 12 LST. Furthermore, the wind direction, wind velocity, and temperature elements were compared with observed values to verify the WRF numerical simulation results used in this study, and they simulated well in accordance with the trend of the observed values. The wind was generally weak in the high-concentration episode days that were chosen through surface weather chart and the numerical simulation results for wind field, and the air pollutants were congested due to the effects of the resulting local winds, thereby causing a high concentration of air pollutants. Furthermore, the HYSPLIT model was performed with the WRF numerical simulation results as input data. As a result, they originated from China and flowed into Gimhae in all eight days, and the lowest concentration appeared on the days when recirculation occurred.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.125-127
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• 2010