서울의 두 평야 지역 4km{\times}4km에 대한 부지 고유의 지진 응답 특성 평가를 위하여 대상 지역내 총 350개의 시추 자료를 활용하였다. 국내 내륙 지역의 공내 탄성파 시험의 자료와 시주 자료를 이용하여 N-V_s 상관관계를 도출하고, 이를 토대로 선정된 350 시추 위치에서의 깊이별 전단파 속도(Vs) 분포를 결정하여 등가선형 기법의 부지 응답 해석을 수행하였다. 현행 지반 분류 기준인 심도 30m까지의 평균 Vs (Vs30)는 대상 지역 내에서 250{\~}550 m/s의 분포를 보였고, 그에 따라 대부분의 부지가 지반 분류 C와 D로 분류되었다. 서울 평야 지역의 부지 고유 주기는 국내 지반 증폭 계수의 근간인 미국 서부 지역에 비해 매우 작은 0.1{\~}0.4초의 분포를 보였다. 비록 몇몇 부지에서 토사 층 내에 연약한 지층이 존재함에 따라 기저 고립 효과가 발생하여 현행 단주기 증폭 계수가 지반 운동을 과대평가하기도 하지만, 미국 서부 지역과의 지반 조건 차이로 인해 전반적으로 서울 평야 지역에서는 현행 국내 내진 설계 기준의 단주기(0.1{\~}0.5초) 증폭 계수(Fa)는 지반 운동을 과소평가하고 중장주기(0.4{\~}2.0초) 증폭 계수(Fv)는 지반 운동을 과대평가하고 있다

본 연구에서는 복사전달모델을 통하여 9.7μm오존 흡수대에 미치는 오존 및 열적(i.e., 지표 온도) 효과를 각각 조사하였다. 또한 오존주의보가 수도권 지역(37.2-37.7 N, 125.7-127.2 E)에 발령되었던 2003년 4일에 대한 위성(MODIS Aqua; ECT 13:30) 및 지상 오존(79개 관측소)의 동시 관측 자료를 기초로 지상 오존에 대한 원격탐사 방법을 제시하였다. 여기서 구름 효과를 제거하고 오존 연직 분포를 분석하기 위하여 종관기상 자료도 사용하였다. 주어진 오존 농도(327~391 DU)에 대하여 산출된 9.6μm에서의 상향 복사휘도는 표면온도 Ts = 290 K에서 5.52~5.78Wm-2sr-1, 그리고 Ts = 325 K에서는 9.00~9,57Wm-2sr-1이었다. 따라서 오존 흡수 세기(i.e., 11μm와 9.7μm 밝기온도 간의 차; T11-9.7)를 이용한 오존 원격탐사 시에 세기 변화에 대한 순수한 오존 효과는0.26Wm-2sr-1/64 DU, 그리고 열적 효과는 0.31Wm-2sr-1/35 K이었다. 본 연구에서는 흡수 세기와 지상 관측 간에 유의적인 상관을 보이는 경우에 대하여 적외선 위성 관측에서 지상 오존을 원격탐사하는 경험식을 유도하였다. 유도된 지상 오존 농도와 관측값과의 상관은 49~63%로 유의수준 1%에서 유의미하였다. 경험식을 개선하기 위하여는 지상 오존 대신에 대류권 오존 자료를 사용하고, 성층권 오존 변화도 고려하는 후속 연구가 요구된다.

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.

This study focused on comparing the meteorological conditions in the Atmospheric Boundary Layer (ABL) on high-event days and non-event days in the Seoul Metropolitan Area (SMA). We utilized observed PM10 and meteorological variables at the surface as well as at the upper heights. The results showed that high-event days were consistently associated with lower wind speed, whereas wind direction showed no particular difference between high-event and non-event days with frequent westerlies and northwesterlies for both cases. During high-event days, the temperature was much warmer than the monthly normal values with a sharp increasing trend, and Relative Humidity (RH) was higher than the monthly normal, especially on high-event days in February. During high-event days in spring, a double inversion layer was present at surface and upper heights. This indicates that stability in the multi-layer is an important indicator of higher PM10 concentrations. Net radiation in spring and winter is also closely associated with higher PM10 concentrations. Strong net radiation resulted in large sensible heat, which in turn facilitated a deeper mixing height with diluted PM10 concentrations; in contrast, PM10 concentrations were higher when sensible heat in spring and winter was very low. We also confirmed that convective and friction velocity was higher on non-event days than on high-event days, and this was especially obvious in spring and winter. This indicated that thermal turbulence was dominant in spring, whereas in winter, mechanical turbulence was dominant over the SMA.

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.

The long-term variability of summer heavy rainfall in the Seoul metropolitan area was investigated in this study for the period of 1970-2018. The study period was divided into two phases; first phase from 1970 to 1994 and the second phase was 1995 to 2018. Long-term variability of summer heavy rainfall was examined using the change-point analysis method. Annual mean heavy rainfall amounts showed increasing trends in Seoul and Incheon during summer monsoon season (June to August). Results revealed that the changes in frequency and amount of heavy rainfall were observed larger in the months of July and August as compare to June during the second phase. The upper-level trough was prominently developed at the west of the Seoul metropolitan area and the core region of the upper-level jet was shifted to the east of the area during second phase. The western North Pacific subtropical high was expanded westward and moisture flux flowed along the southwesterly wind, resultant increasing moisture supply. The temperature and humidity tended to increase recently at the lower and mid-levels.

In this study, the impacts of local meteorology caused by tidal changes in the West Sea on ozone distributions in the Seoul Metropolitan Area (SMA) were analyzed using a meteorological model (WRF) and an air quality (CMAQ) model. This study was carried out during the day (1200–1800 LST) between August 3 and 9, 2016. The total area of tidal flats along with the tidal changes was calculated to be approximately 912 km2, based on data provided by the Environmental Geographic Information Service (EGIS) and the Ministry of Oceans and Fisheries (MOF). Modeling was carried out based on three experiments, and the land cover of the tidal flats for each experiment was designed using the coastal wetlands, water bodies (i.e., high tide), and the barren or sparsely vegetated areas (i.e., low tide). The land cover parameters of the coastal wetlands used in this study were improved in the herbaceous wetland of the WRF using updated albedo, roughness length, and soil heat capacity. The results showed that the land cover variation during high tide caused a decrease in temperature (maximum 4.5℃) and planetary boundary layer (PBL) height (maximum 1200 m), and an increase in humidity (maximum 25%) and wind speed (maximum 1.5 ms-1). These meteorological changes increased the ozone concentration (about 5.0 ppb) in the coastal areas including the tidal flats. The increase in the ozone concentration during high tide may be caused by a weak diffusion to the upper layer due to a decrease in the PBL height. The changes in the meteorological variables and ozone concentration during low tide were lesser than those occurring during high tide. This study suggests that the meteorological variations caused by tidal changes have a meaningful effect on the ozone concentration in the SMA.

The adequacy of urban air quality monitoring networks in the largest metropolitan city, Seoul was evaluated using multivariate analysis for SO2, NO2, CO, PM10, and O3. Through cluster analysis for 5 air pollutants concentrations, existing monitoring stations are seen to be clustered mostly by geographical locations of the eight zones in Seoul. And the stations included in the same cluster are redundantly monitoring air pollutants exhibiting similar atmospheric behavior, thus it can be seen that they are being operated inefficiently. Because monitoring stations groups representing redudancy were different depending on measurement items and several pollutants are being measured at the same time in each air monitoring station, it is seemed to be not easy to integrate or transmigrate stations. But it may be proposed as follows : the redundant stations can be integrated or transmigrated based on ozone of which measures are increasing in recent years and alternatively the remaining pollutants other than the pollutant exhibiting similar atmospheric behavior with nearby station’s can be measured. So it is considered to be able to operate air quality monitoring networks effectively and economically in order to improve air quality.

최근 국지성 도시홍수탐지 및 예측의 실패는 기존 대형 S밴드 레이더 관측망의 저층관측 한계를 시사한다. 기존 관측망의 한계를 극복하고자 돌발홍수의 조기탐지 및 분석을 위한 새로운 첨단관측기법인 X밴드 이중편파레이더 관측망(X-Net)의 필요성이 대두되었다. 본 연구에서는 X-Net 실증 테스트베드를 구축하고자 수도권 지역에서 X밴드 이중편파 레이더 설치를 위한 후보지를 조사하고 각 후보지의 적합성 판단을 위해 현장조사, 전파환경조사를 수행하여 최적 관측망을 검토하였다. 최적의 관측망을 선정하기 위해 레이더 빔시뮬레이션을 통하여 각 후보지의 빔차폐율을 조사하고 설치후보지에 대한 현장조사를 통하여 기존시설(전력, 도로, 통신망 등)의 가용성을 판단하였다. 이와 함께 전파환경조사를 실행하여 X밴드 대역의 주파수 할당 가능성을 평가하고, 각 후보지별 간섭이 없는 주파수대역을 조사하였다.

In order to clarify the impact of emissions reductions on the air quality over Metropolitan area of Korean Peninsula, several numerical experiment and analysis of integrated process rate(IPR) of ozone were carried out. Numerical models used in this study are WRF for the estimate the meteorological elements and CMAQ for assessment of ozone concentration. As result in the sensitive test of VOC/NOx reduction experiments, although VOC reduction tends to induce the different impact on the advection and photochemical reaction rate of ozone in urban area and rural area, the mechanism of ozone appeared to be more sensitive to the reduction of VOC than that of NOx over the metropolitan and its surround area. So the control of VOC emission inventories is an effective means to decrease the ozone concentrations around this area.

The Government had devised legislation of Special Act and drew up guidelines for improving air quality in Seoul Metropolitan area. In 2007 local government of Seoul, Incheon and Gyeonggi conducted the results of application policy by reduced air pollutants emission for the first time. Although there was reduction of air pollutant emission in each local government, it was ineffective as expected using air pollution monitoring database. Therefore we worked out a way to prepare modeling input data using the results of enforcement plan. And we simulated surface NO_2 and PM10 before and after decrease in air pollutants emission and examine reduction effects of air pollution according to enforcement regulation except other influence, by using MM5-SMOKE-CMAQ system. Each local government calculated the amount of emission reduction under application policy, and we developed to prepare input data so as to apply to SMOKE system using emission reduction of enforcement plan. Distribution factor of emission reduction were classified into detailed source and fuel codes using code mapping method in order to allocate the decreased emission. The code mapping method also included a way to allocate spatial distribution by CAPSS distribution. According to predicted result using the reduction of NOx emission, NO_2 concentration was decreased from 19.1 ppb to 18.0 ppb in Seoul. In Gyeonggi and Incheon NO_2 concentrations were down to 0.65 ppb and 0.68 ppb after application of enforcement plan. PM10 concentration was reduced from 18.2 ㎍/㎥ to 17.5 ㎍/㎥ in Seoul. In Gyeonggi PM10 concentration was down to 0.51 ㎍/㎥ and in Incheon PM10 concentration was decreased about 0.47 ㎍/㎥ which was the lower concentration than any other cities.

This study were to simulate major criteria air pollutants and estimate regional source-receptor relationship using air quality prediction model (TAPM ; The Air Pollution Model) in the Seoul Metropolitan area. Source-receptor relationship was estimated by contribution of each region to other regions and region itself through dividing the Seoul metropolitan area into five regions. According to administrative boundary, region Ⅰ and region Ⅱ were Seoul and Incheon in order. Gyeonggi was divided into three regions by directions like southern(region Ⅲ), northern(Ⅳ) and eastern(Ⅴ) area. Gridded emissions (1km×1km) by Clean Air Pollicy Support System (CAPSS) of National Institute of Environmental Research (NIER) was prepared for TAPM simulation. The operational weather prediction system, Regional Data Assimilation and Prediction System (RDAPS) operated by the Korean Meteorology Administration (KMA) was used for the regional weather forecasting with 30km grid resolution. Modeling period was 5 continuous days for each season with non-precipitation . The results showed that region Ⅰ was the most air-polluted area and it was 3～4 times more polluted region than other regions for NO2, SO2 and PM10. Contributions of SO2 NO2 and PM10 to region Ⅰ, Ⅱ and Ⅲ were more than 50 percent for their own sources. However region Ⅳ and Ⅴ were mostly affected by sources of region Ⅰ, Ⅱ and Ⅲ. When emissions of all regions were assumed to reduce 10 and 20 percent separately, air pollution of each region was reduced linearly and the contributions of reduction scenario were similar to those of base case. As input emissions were reduced according to different ratio - region Ⅰ 40 percent, region Ⅱ and Ⅲ 20 percent, region Ⅳ and Ⅴ 10 percent, air pollutions of region Ⅰ and Ⅲ were decreased remarkably. The contributions to regionⅠ, Ⅱ, Ⅲ were also reduced for their own sources. However, region Ⅰ, Ⅱ and Ⅲ affected more regions Ⅳ and Ⅴ. Shortly, graded reduction of emission could be more effective to control air pollution in emission imbalanced area.

The relationship between air temperatures and the fraction of urban areas (FUA) and their linear regression equation were estimated using land-use data provided by the water management information system (WAMIS) and air temperatures by the Korea Meteorology Administration (KMA) in the Seoul metropolitan area (SMA) during 1975 through 2000. The future FUA in the SMA (from 2000 to 2030) was also predicted by the urban growth model (i.e., SLEUTH) in conjunction with several dataset (e.g., urban, roads, etc.) in the WAMIS. The estimated future FUA was then used as input data for the linear regression equation to estimate an annual mean minimum air temperature in the future (e.g., 2025 and 2030). The FUA in the SMA in 2000 simulated by the SLEUTH showed good agreement with the observations (a high accuracy (73%) between them). The urban growth in the SMA was predicted to increase by 16% of the total areas in 2025 and by 24% in 2030. From the linear regression equation, the annual mean minimum air temperature in the SMA increased about 0.02℃/yr and it was expected to increase up to 8.3℃ in 2025 and 8.7℃ in 2030.

This study examines the local ozone photochemistry in the urban air. The photochemical formation and destruction of ozone was modeled using a photochemical box model. For the model prediction of ozone budget, measurements were carried out from an urban monitoring station in Seoul (37.6˚N, 127˚E), Korea for intensive sampling time period (Jun. 1～15, 2003). Photochemical process is likely to play significant role in higher ozone concentrations during the sampling period. The results of model simulation indicated that photochemical ozone production pathway was the reaction of NO with HO2 while ozone destruction was mainly controlled by a photochemical destruction pathway, a reaction of H2O with O(1D). The contribution of NMHCs to formation and destruction of ozone in the urban was significant. This was entirely different from remote marine environment. The rates of net photochemical ozone production ranged from 0.1 to 1.3 ppbv h-1 during the study period.

화물발생 예측을 위해 주로 이용된 방법은 교통존을 중심으로 한 공간단위의 접근기법이다. 또한 연구사례에 따라 물동량 전수화 방법에 차이가 있고 모형에 포함된 변수가 다른 경우가 많아 일관된 화물발생 예측에 어려움이 있다. 본 연구에서 시도한 물동량 단위 예측기법은 개별 사업체를 대상으로 유출·입하는 화물 물동량과 종업원수, 매출액, 연면적, 부지면적 등 사업체의 특성을 이용하여 사업체 단위로 화물발생을 예측하는 것으로 공간단위 접근기법보다 간편하고 다른 지역에 적용이 가능한 장점이 있다. 연구의 대상은 수도권에 소재한 사업체이며 매출액을 설명변수로 선정하여 회귀식을 추정하고 모형의 적합성을 검증하였다. 회귀모형의 형태는 지수형으로 매출액이 증가함에 따라 화물발생의 규모도 커지는 특징을 갖는다. 본 연구는 교통 존 단위가 아닌 사업체 단위로 화물발생을 예측하는 보다 미시적인 연구방법을 개발함에 의의가 있다.