식물사회네트워크란 식물사회를 이해하기 위한 기존의 식물사회학적 방법과 사회과학에서 최근에 주목받고 있는 사회연결 망 분석 방법을 접목하여 식물사회연결망을 시각화하고 분석하는 것을 말한다. 구축 및 분석 과정은 조사구 설정 및 출현 수종 조사, 종간결합분석, 소시오그램 작성, 네트워크 구조 및 중심성 분석 순으로 진행된다. 식물사회네트워크를 구축하기 위해 본 연구는 해안식생과 내륙식생을 동시에 볼 수 있는 부산광역시를 중심으로 다양한 상관우점식생이 포함되도록 708개 조사구를 설치하여 출현 수종을 조사하였다. 조사 결과, 출현한 수종은 모두 195종이었으며, 상록수 42종, 낙엽수 151종, 반상록수 2종으로 나탔으며, 전체 출현수종을 중심으로 종간결합분석을 실시하였다. 종간결합 분석 결과, 친화종수는 사스레피 나무(47종), 마삭줄(46종), 감태나무(44종), 팥배나무(44종), 광나무(41종) 순으로 나타났으며, 이를 바탕으로 gephi 0.9.2. program을 활용하여 소시오그램을 작성하였다. 작성된 소시오그램은 해안에서 주로 출현하는 그룹과 그렇지 않은 그룹으로 나뉘어져 있어 부산광역시 산림식생의 지리적 분포특성을 반영하고 있었다. 네트워크 구조를 분석한 결과, 1,709개의 연결선 (link)이 나타났고, 한 수종과 종간결합을 갖는 종수의 평균은 약 17.5개였다. 밀도는 0.09, 지름은 5, 평균 경로거리는 2.268로 분석되었는데, 사회과학분야의 네트워크 특성과 정밀한 비교 분석을 위해 앞으로 다양한 식물사회네트워크 구축이 진행되어야 할 것으로 판단되었다. 부산광역시 식물사회네트워크에서는 사스레피나무, 감태나무, 광나무, 마삭줄 등이 중심성 이 높은 것으로 나타났다.

In this study, numerical simulations using community multiscale air quality (CMAQ) were conducted to analyze the change in ozone (O3) concentration due to the reduction in nitrogen oxides (NOx) and volatile organic compounds (VOCs) emissions in Busan. When the NOx and, VOCs emissions were reduced by 40% and, 31%, respectively, the average O3 concentration increased by 4.24 ppb, with the highest O3 change observed in the central region (4.59 ppb). This was attributed to the decrease in O3 titration by nitric oxide (NO) due to the reduction of NOx emissions in Busan, which is classified as a VOCs-limited area. The distribution of O3 concentration changes was closely related to NOx emissions per area, and inland emissions were highly correlated with daily maximum concentrations and 8-h average O3 concentrations. Contrastingly, the effect of emission reduction depended on the wind direction. This suggests that the emission reduction effects may vary depending on the environmental conditions. Further research is needed to comprehensively analyze the emission reduction effects in Busan.

This study analyzed characteristics of ozone (O3) formation regimes in Busan over a period of recent five years (2015~2019) and compared the findings with those obtained in Seoul. We employed four observed variations: early morning commuting-hour (i.e., 06:00-09:00 LST) nitrogen dioxide (NO2), peak-hour (i.e., 12:00-16:00 LST) O3, 8-hour average O3 (MDA8 O3), and △O3 (=O3_max- O3_min) in Busan and Seoul. In addition, the NO2-O3 relation was assessed to interpret which of NOx-limited or volatile organic compound (VOC)-limited was dominant. In Busan, the annual mean O3 concentration was relatively higher than in Seoul, whereas there were fewer high-concentration days. The Pearson correlation coefficients (R) between Early morning-hour NO2 and the Peak-hour O3 was positive (but close to zero) in Busan and negative in Seoul. Likewise, the R between the Early morning-hour NO2 and the △O3 showed a relatively considerable positive correlation (R=+0.4~0.5) in Busan, while a weak positive correlation (R=+0.1~0.2) in Seoul. From this result, it can be inferred that the O3 formation regime in Busan was intrepreted to be nearly neutral or relatively closer to the NOx-limited regime than Seoul, while Seoul to the VOC-limited regime. The study findings imply that O3 control strategies should be applied differently in Busan and Seoul. The results here were inferred from surface NO2 and O3 observations, and the varification studies based on in-situ VOCs measurements would be needed.

In this study, impact of the COVID-19 outbreak on PM2.5 mass and its five chemical components (NH4 +, NO3 -, SO4 2-, OC, EC) in Busan was evaluated, and compared with that of Seoul. The study period over the recent three years was sub-divided into two periods: Pre-COVID (2018~2019) and COVID (2020) periods, and the differences in observed annual and monthly variations between the two periods were explored here. The results indicated that annual mean PM2.5 mass concentrations decreased during the COVID period by 16% in Seoul and 29% in Busan, and the satellite-observed annual average of aerosol optical depth (AOD) over the Korean Peninsula also decreased by approximately more than 10% compared with that of the Pre-COVID period. All of the five chemical components decreased but no particular changes were found in their fractions occupied during the COVID period. However, over the Lock-down period (2020-March), the sulfate fraction decreased in Seoul, mostly reflecting the recent Chinese trends of aerosol characteristics, whereas the nitrate fraction considerably decreased in Busan, which was attributable to the local emission changes and their variabilities in Busan. Other meteorological characteristics such as higher frequencies of easterly winds in the Busan area during the COVID period were also discussed in comparison with those in the Seoul area.

This study analyzed the characteristics of high PM2.5 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 PM2.5 city emissions, whereas fugitive PM2,5 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 PM2.5 episode days that meet the criteria of ERMP levels. In Busan, Ulsan, and Gyeongnam region, 15, 16, and 8 days of extremely high PM2.5 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.

We analyzed the recent characteristics of Particulate Matter (PM) including PM10 (PM with diameter of less than 10μm) and PM2.5 (PM with diameter of less than 2.5μm) observed in Busan metropolitan area, and compared them with those measured in Seoul metropolitan area. This analysis includes the monthly, seasonal, and annual variations and differences, in emissions and chemical compositions observed in both Busan and Seoul areas. Synoptic meteorological conditions were investigated at the time when high PM concentrations occurred in each of the two areas. The results showed clearly decreasing trends of annual mean concentrations with strong seasonal variations: lower in summer and higher in winter in both areas. In comparison with Seoul, the seasonal variation in Busan demonstrated relatively lower, but showed greater summer fluctuations than in Seoul metropolitan area. This is implying the importance of secondary generation of PM in summer via active photochemical reaction in Busan area. In high concentration days, Busan’s chemical composition of sulfate was higher than that of nitrate in summer, whereas nitrate was higher than sulfate in Seoul. The ratios of NO3 - to SO4 2-(N/S ratio) showed lower in Busan approximately by a factor of 1/2(half of N/S ratio) in Busan compared with that in Seoul. Others such as synoptic characteristics and emission differences were also discussed in this study.

This study　suggested a vegetation　restoration plan for a coastal area where the ecosystem conservation fund return project, targeting the whole area of Dalmaji-gil, located in Haeundae, Busan. After distinguishing if it would be a proper site for the operation of the ecosystem　conservation fund return project by analyzing the ecological environment, human environment, and the current status of land owners, the target species for vegetation restoration was determined, and the facilities and programs were selected in accordance with the spatial division of the biosphere reserve. The basic direction is as follows. First, is the expansion of green space and the securement of life habitats downtown. Second, is the conservation of core areas by separating the conserved area from the space for use. Third, is the establishment of ecological resting space and the reinforcement of an ecological educational programs. The significance of this study is to suggest a vegetation restoration plan of a coastal area, fully utilizing the existing vegetation of the subject area, by suggesting the land use and flow planning, environmental improvement (vegetation restoration) plan, life habitats establishment plan, planting plan, and hydrologic plan, facilities, maintenance, and monitoring plan based on the basic direction. This study would provide useful basic data for ecosystem conservation and restoration in the Korean Peninsula, surrounded by the ocean on three sides.

Temporal and spatial variations in surface ozone concentrations in Busan were investigated by using observation data from urban air quality sites during 2001-2016. The annual ozone concentrations showed a significant increasing trend of +0.40 ppb yr-1 in this period, with a more rapid increase of +0.81 ppb yr-1 since 2010. For the monthly analysis, the increase in ozone concentration was the greatest in August (+0.68 ppb yr-1). These ozone trends were due mainly to rising temperature (+0.05℃ yr-1) and weak decreasing precipitation (－6.42 mm yr-1). However, the extreme weather events (heat wave, localized heavy rain, etc.) lead to an increase in short-term variability of ozone since 2010. The relatively low ozone concentrations in the downtown area were caused by high NOx emissions from mobile sources. The increases in ozone concentrations were observed at most of the air quality monitoring sites due to the reductions in anthropogenic emissions of NOx during 2001-2015. However, in the southern coastal area, lower rates of increase in ozone concentrations were observed by –0.10~0.25 ppb yr-1 due to the significant NOx emitted by ships in the Busan port and Busan new port.

In order to investigate the PM10 concentration trend and its characteristics over five different sub area in Busan from 2013 to 2015, data analysis with considering air flow distribution according to its topography was carried out using statistical methodology. The annual mean concentrations of PM10 in Busan tend to decrease from 49.6㎍/m³ in 2013 to 46.9㎍/m³ in 2015. The monthly mean concentrations value of PM10 were high during spring season, from March to May, and low during summer and fall due to frequent rain events. The concentration of PM10 was the highest in five different sub-area in Busan. High concentration episodes over 90 percentile of daily PM10 concentration were strongly associated with mean daily wind speed, and often occurred when the westerly wind or southwesterly wind were dominant. Regardless of wind direction, the highest correlation of PM10 concentrations was observed between eastern and southern regions, which were geographically close to each other, and the lowest in the western and eastern regions blocked by mountains. Wind flow along the complex terrain in Busan is also one of the predominant factors to understand the temporal variation of PM10 concentrations.

Now a days, frequency of abnormally high temperatures like heat wave by global warming and climate change is increasing constantly and the number of patient with heat related illness are jumping rapidly. In this study, we chose the case day for the heat wave in Busan area(Busan and Yangsan), 2013 which it was the most hottest year during 21th century. And then, we analysed the weather condition using automatic synoptic observing system(ASOS) data. Also, four indices, heat index(HI), wet bulb globe temperature(WBGT), Man-ENvironment heat EXchange model(MENEX)’s results like Physiological subjective temperature(PST), Physiological strain(PhS), were calculated to evaluate the thermal comfort and stress quantitatively. However, thermal comfort was different as the each station and thermal comfort index during same time. Busan’s thermal indices (HI: hot, WBGT: sweltering, PST: very hot, PhS: very hot) indicated relatively higher than Yansan’s (HI: very hot, WBGT: sweltering, PST: very hot, PhS: sweltering). It shows that Busan near coast is relatively more comfortable than Yangsan located in inland.

The spatial and temporal changes of the annual mean urban heat island(UHI) intensity were investigated using near surface temperature data measured at 16 automatic weather systems(AWS) in Busan metropolitan area(BMA) during the 11-yr period, from 2000 to 2010. For nighttime, the annual mean UHI intensity at Dongnae(U1) in 2000 was weaker than it in 2010. However the change of the annual mean UHI intensity at Daeyeon(U2) during 11 years was different from it at U1. The annual frequency of the UHI intensity over 5℃ considerably increased at U2 and decreased at U1 during 11 years. The center of the UHI also spatially shifted southward with Daeyeon and Haeundae in BMA. It would be caused by the increase of urban area, population-density and transportation near U2 and by the decrease of them near U1. We found that the spatial and temporal differences of the UHI intensity have coincided with changes of land-use, population density and transportation in BMA.

The emissions of several air pollutants (NOx, CO, VOCs, etc.) for the replacement of all diesel buses by Compressed Natural Gas (CNG) buses were estimated in the Busan Metropolitan Area (BMA). These emissions were calculated from emission factors considering the different driving speeds with bus routes, distance traveled, and deterioration factors. For the purpose of this study, three categories of fuel type were selected: (1) the combination of diesel (65%) and CNG buses (35%) (DSL+CNG case), (2) all diesel buses (DSL case), and (3) all CNG buses (CNG case). The emissions of NOx and CO in the CNG case were estimated to be significant decreases (by about 50% and 98%, respectively) relative to the DSL case. Conversely, the emission of VOCs (980.7 ton/year) in the CNG case were a factor of 3.3 higher than that (299.8 ton/year) in the DSL case. In addition, the diurnal variations of emissions between two city buses (e.g. diesel and CNG) and all other vehicles were distinctly different because the two city buses operate at a regular time interval. Our overall results suggest the possibility that the pollutant emissions from the CNG buses can exert less influence on air quality in the target area than those from the diesel buses.

In order to clarify the impacts of thermal difference in atmospheric boundary layer due to the different sophistication of building information in Busan metropolitan areas, several numerical simulations were carried out. ACM (Albedo Calculation Model) and WRF (Weather Research and Forecasting) was applied for estimating albedo and meteorological elements in urban area, respectively. In comparison with coarse aggregated and small buildings, diurnal variation of albedo is highly frequent and its total value tend to be smaller in densely aggregated and tall buildings. Estimated TKE and sensible heat flux with sophisticatedly urban building parameterization is more resonable and valid values are mainly induced by urban building sophistication. The simulation results suggest that decreased albedo and increased roughness due to skyscraper plays an important role in the result of thermal change in atmospheric boundary layer.

We have investigated coarse wind sectors in Busan metropolitan area and simulated detailed wind field using local atmospheric circulation model, RAMS in preceding studies (Part I, Part II). In this study, we divided and analyzed local wind sector in Busan according to the preceding results. We found that Busan metropolitan area is divided into 2 or 3 local wind sector in each coarse wind sector. The 9 coarse wind sectors were classified into 20 local wind sectors in total. But three local wind sectors were finally excluded because of these sectors were located on the complex hill area and the sea. Local wind sectors, therefore, in Busan metropolitan area were defined as 17 regimes. We assessed the location of air quality monitoring sites at Busan metropolitan area using the information of these wind sectors. Most of these were located at proper points, but 6 sites were placed at 3 local wind sectors as a couple and no site was set up at 3 other sectors. Hence the location of these sites was in need of rearrange.

We have analysed the observed surface and vertical meteorological data to get atmospheric information over the Busan metropolitan area. For this, we have selected 10 days in all season such as spring, summer I(Jangma season), summer II(hot season), autumn and winter. The result which have performed cluster analysis using atmospheric data represented that these days are included to most frequently appeared synoptic cluster. We have simulated wind field around Busan metropolitan area which is assigned as 1km2 using RAMS. The calculated air temperature and the wind speed was similar to the observed the that, and the trends of daily variation showed good agreement. RMSE and IOA also showed reliable value. These results indicated the RAMS is able to simulate and predict detailed atmospheric phenomenon.

In this study, climate analysis and wind sector division were conducted for a propriety assessment to determine the location of air quality monitoring sites in the Busan metropolitan area. The results based on the meteorological data(2000～2004) indicated hat air temperature is strongly correlated between 9 atmospheric monitoring sites, while wind speed and direction are not. This is because wind is strongly affected by the surrounding terrain and the obstacles such as building and tree. In the next stage, we performed cluster analysis to divide wind sector over the Busan metropolitan area. The cluster analysis showed that the Busan metropolitan area is divided into 6 wind sectors. However 1 downtown and 2 suburbs an area covering significantly broad region in Busan are not divided into independent sectors, because of the absence of atmospheric monitoring site. As such, the Busan metropolitan area is finally divided into 9 sectors.

The purpose of this study is to estimate the air quality of subway stations having underground platforms in Busan Metropolitan City, from September to November 2000, over seven times. The places of the investigation include Yonsan-dong station, Somyon station, Busan station, Nampo-dong station, and Dusil station. Samplings were conducted at three points in each station, i.e. gates, ticket gates, and platforms. CO, NO, NO2, and O3 were the main components of air for this analysis. In order to more fully understand station environments, we also measured an air temperature at each point. The results showed that the O3 average concentration of Yonsan-dong station was higher than others with 38～51ppb. The average concentration of NO was high at the ticket gate and platform at Somyon station (119ppb, 122ppb) and Nampo-dong station (102ppb, 100ppb). These results show that the air pollution of stations with underground shopping malls were higher than others. At Somyon station having a junction station, NO and NO2 concentration levels of platform-2 (noncrowded) were higher than platform-1 (crowded). This is most likely due to the accumulation of air pollutants and inadequate ventilation systems. To find the relationship of the indoor (platform) and outdoor (gate), we analyzed the I/O ratio. The averages of CO and O3 were both higher than one: 1.16 and 1.82, respectively. In the correlations between each material and the others, NO vs NO2 was the highest with R=0.63. In the correlations between indoor and outdoor, O3 was the highest with R=0.64.

The purpose of this study is designed to estimate the air quality of subway stations that have the underground platforms in Pusan Metropolitan City, from September to November 2000, over seventimes. The subjects include Yonsan-dong station, Somyon station, Pusan station, Nampo-dong station, and Tushil station. The samplings were conducted at three points of each station, i.e. gates, ticket gates, and platforms. The major materials for analysis were CO, NO, NO2, and O3. The experiment was conducted at 7:00 pm with KIMOTO HS-7 Handy sampler and Tedlar Bag of SKC INC(U.S.A). In order to more fully understand station environments, we also measured temperature at each point. The results showed that O3 average concentration at Yonsan-dong station was higher than others with 38～51 ppb. The average concentration of NO was high at ticket gate and platform at Somyon station(119 ppb, 122 ppb), Nampo-dong station(102 ppb, 100 ppb). These results show that the air pollution of stations with underground shopping malls was higher than others. At Somyon station having a junction station, NO and NO2 concentration level of platform-2(noncrowded) was higher than platform-1(crowded). This is most likely due to the accumulation of air pollutants and inadequate ventilation systems.