• Journal of Environmental Science International
• /
• v.12 no.10
• /
• pp.1033-1041
• /
• 2003

Hourly data of PM10 concentration collected from nine automatic air quality monitoring stations in Busan from 1999 to 2002 were analyzed to evaluate the spatio-temporal variation and meteorological characteristics of PM10 episodes in Busan metropolitan area. Mean concentrations ranged from 47$\mu\textrm{g}$/㎥ to 77$\mu\textrm{g}$/㎥. For most stations, mean seasonal hourly concentrations are lowest in summer and highest in spring. PM10 episode above daily mean standard(150$\mu\textrm{g}$/㎥) exhibited a maximum frequency at Gamjeondong and a minimum at Dongsamdong, and a maximum in March and a minimum in July and August. The diurnal variation of PM10 episode days is strongly influenced by traffic loads and meteorological conditions.

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

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

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

• Journal of Environmental Science International
• /
• v.30 no.10
• /
• pp.789-802
• /
• 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 Korean Society for Atmospheric Environment
• /
• v.31 no.2
• /
• pp.131-142
• /
• 2015

This study investigated physicochemical and optical characteristics for three episodes of Asian dust, stagnant haze and long-range transport haze and for one clean day. $PM_{10}$ mass concentration during Asian dust and two haze days was increased by 2~9 times compared to that of clean episode. During Asian dust episode, coarse particle concentration was increased and the mass concentration of calcium in a coarse mode ($1.8{\sim}10{\mu}m$) was $5.4{\mu}g/m^3$ which was 7 times higher than that of clean episode. The calcium was presented as a form of $CaCO_3$ in a coarse mode. During the two haze episodes, fine particle (< $1.8{\mu}m$) concentration was increased and secondary inorganic pollutants such as sulfate, ammonium and nitrate composed of 90% of the total ions. $(NH_4)_2SO_4$ and $NH_4NO_3$ were dominant in a fine mode for stagnant haze episode. But they were the most dominant form in both fine mode and coarse mode for long-range transport haze episode. According to the optical properties for each episode (Asian dust, stagnant haze and long-range transport haze) were classified as dust, black carbon and mixture, respectively.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.2
• /
• pp.215-224
• /
• 2004

We report the high concentration episodes for PM$_{10}$, SO$_2$, NO$_2$, and $O_3$ in many urban areas Korea during 2002. The high concentration episodes are identified based on the National Ambient Air Quality Standards and the observations obtained from the Regional Air Monitoring Network composed of approximately 160 air pollution monitoring stations located in a number of major or big cities in South Korea including Seoul, Pusan, Daegu, and Incheon cities. The results show that the twenty cases of high concentration episodes in 2002 consists of both ozone warning episodes (6 cases) and high PM$_{10}$ concentration cases (14 cases), and one half of the latter are found to occur in association with the Yellow Sand (Asian Dust) phenomena. The most outstanding characteristics of the reported episodes are the excessively high levels of maximum PM$_{10}$ concentrations during the Yellow Sand period (i.e., exceeding 3,000$\mu\textrm{g}$/㎥ in April, 2002) and their variable occurrence frequencies across seasons. The high ozone concentration episode days are mainly resulting from both the high photochemical reactions and poor ventilations. The high PM$_{10}$ concentration days during non Yellow Sand periods, however, mostly occurred under the influence of synoptic meteorological conditions such as stagnant or slowly passing high pressure centers, and consequently prevailing weak wind speeds over the Korean peninsula. The overall results of our study thus suggest the importance of both synoptic and local meteorological factors for high concentration levels in the major and/or big cities in Korea.n Korea.

• Journal of Environmental Science International
• /
• v.29 no.7
• /
• pp.761-772
• /
• 2020

This research investigated the meteorologically relevant characteristics of high PM_2.5 episodes in Busan. The number of days when daily mean PM₁₀ concentration exceeded 100 ㎍/㎥ and the PM_2.5 concentration exceeded 50 ㎍/㎥ over the last four years in Busan were 24 and 58, respectively. Haze occurrence frequency was 37.6% in winter, 27.4% in spring, 18.6% in fall, and 16.4% in summer. Asian dust occurrence frequency was 81.8% in spring, 9.1% in fall and winter, and 0% in summer. During summer in Busan, high PM_2.5 episode occurred under the following meteorological conditions. 1) Daytime sea breeze. 2) Mist and haze present throuout the day. 3) Anti-cyclone located around the Korean peninsula. 4) Stable layer formed in the lower atmosphere. 5) Air parcel reached Busan by local transport rather than by long-range transport. These results indicate that understanding the meteorological relevance of high PM_2.5 episodes could provide insight for establishing a strategy to control urban air quality.

• Journal of Korean Society for Atmospheric Environment
• /
• v.31 no.3
• /
• pp.223-238
• /
• 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.

• Annals of Clinical Neurophysiology
• /
• v.2 no.2
• /
• pp.119-124
• /
• 2000

Background : We studied EEG changes during pilocarpine-induced status epilepticus(SE), a widely used model whose EEG characteristics have not been fully described previously. Methods : Male Sprague-Dawley rats weighing 250-350 grams were used as subjects. SE was induced 5-7 days after placement of chronic epidural electrodes, using 360-380 mg/Kg pilocarpine IP. Rats were observed with continuous EEG recording following pilocarpine injection until end of the SE episode. Results : SE occurred in 10/12 rats studied. SE began with a series of discrete seizures $11.1{\pm}3.93$ minutes after pilocarpine injection. $5.2{\pm}2.71$ seizures occurred over $10.9{\pm}4.62$ minutes, until the EEG converted to a waxing and waning pattern, during which the amplitude and frequency of epileptiform activity increased. After $1.4{\pm}1.82$ minutes, a pattern of continuous high amplitude rapid spiking was established. Continuous spiking continued for $3.4{\pm}0.48$ hours with a very gradual decline in amplitude and frequency, until periodic epileptiform discharges(PEDs) began to occur. The EEG consisted primarily of PEDs for another $7.4{\pm}3.09$ hours, until electrographic generalized seizures began to occur. These continued for $5.8{\pm}4.82$ hours until death. Duration of SE was $17.0{\pm}5.88$ hours. Flat periods were a prominent feature during all EEG patterns in this model. Conclusion : EEG features distinctive in pilocarpine SE(but not unique to it) include flat periods during all patterns and resumption of continuous spiking episodes after the onset of PEDs. The sequence of discrete seizures to waxing and waning to continuous spiking to PEDs was identical to that which has been described in humans and other animal models.