• 한국환경과학회지
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• 제28권4호
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• pp.441-454
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• 2019

The present study analyzes the characteristics of 43 typhoons that affected the Korean Peninsula between 2002 and 2015. The analysis was based on 3-second gust measurements, which is the maximum wind speed relevant for typhoon disaster prevention, using a typhoon disaster prevention model. And the distribution and characteristics of the 3-second gusts of four typhoons, RUSA, MAEMI, KOMPASU, and BOLAVEN that caused great damage, were also analyzed. The analysis show that between May and October during which typhoons affected the Korean Peninsula, the month with the highest frequency was August(13 times), followed by July and September with 12 occurrences each. Furthermore, the 3-second gust was strongest at 21.2 m/s in September, followed by 19.6 m/s in August. These results show that the Korean Peninsula was most frequently affected by typhoons in August and September, and the 3-second gusts were also the strongest during these two months. Typhoons MAEMI and KOMPASU showed distribution of strong 3-second gusts in the right area of the typhoon path, whereas typhoons RUSA and BOLAVEN showed strong 3-second gusts over the entire Korean Peninsula. Moreover, 3-second gusts amount of the ratio of 0.7 % in case of RUSA, 0.8 % at MAEMI, 3.3 % at KOMPASU, and 21.8 % at BOLAVEN showed as "very strong", based on the typhoon intensity classification criteria of the Korea Meteorological Administration. Based on the results of this study, a database was built with the frequencies of the monthly typhoons and 3-second gust data for all typhoons that affected the Korean Peninsula, which could be used as the basic data for developing a typhoon disaster prevention system.

• 한국환경과학회지
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• 제30권9호
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• pp.753-762
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• 2021

This study analyzed the characteristics of strong winds accompanying typhoons for a period of 116 years, from 1904 to 2019, when modern weather observations began in Korea. Analysis shows that the average wind speed and high wind rate caused by typhoons were higher over the sea and in the coastal areas than in the inland areas. The average wind speed was higher over the West Sea than over the South Sea, but the rate of strong wind was greater over the South Sea than over the West Sea. The average wind speed decreased by 1980 and recently increased, while the rate of strong winds decreased by 1985 and has subsequently increased. By season, the strong winds in autumn (september and october) were stronger than those in summer (june, july, and august). Strong winds were also more frequent in autumn than in summer. The analysis of the changes in strong winds caused by typhoons since the 1960s shows that the speed of strong winds in august, september, and october has increased more recently than in the past four cycles. In particular, the increase in wind speed was evident in fall (september and october). Analysis of the results suggests that the stronger wind is due to the effects of autumn typhoons, and the increased possibility of strong winds.

• 대기
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• 제15권2호
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• pp.91-99
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• 2005

This study compares the summer monsoon circulations during a heavy rainfall period over the Korean peninsular from 11 to 18 July 2004, simulated by three widely used regional models; WRF, MM5, and RSM. An identical model setup is carried out for all the experiments, except for the physical option differences in the RSM. The three models with a nominal resolution of about 50 km over Korea are nested by NCEP-DOE reanalysis data. Another RSM experiment with the same cumulus parameterization scheme as in the WRF and MM5 is designed to investigate the importance of the representation of subgrid-scale parameterized convection in reproducing monsoonal circulations in East Asia. All thee models are found to be capable of reproducing the general distribution of monsoonal precipitation, extending northeastward from south China across the Korean peninsula, to northern Japan. The results from the WRF and MM5 are similar in terms of accumulated precipitation, but a slightly better performance in the WRF than in the MM5. The RSM improves the bias for precipitation as compared to those from the WRF and MM5, but the pattern correlation is degraded due to overestimation of precipitation in northern China. In the comparison of simulated synoptic scale features, the RSM is found to reproduce the large-scale features well compared to the results from the MM5 and WRF. On the other hand, the simulated precipitation from the RSM with the convection scheme used in the MM5 and WRF is closer to that from the WRF and MM5 simulations, indicating the significant dependency of simulated precipitation in East Asia on the cumulus parameterization scheme.

• 한국환경과학회지
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• 제25권3호
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• pp.345-359
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• 2016

This study analyze the synoptic meteorological cause of rainfall, rainfall intensity, drop size distribution(DSD), fall velocity and oblateness measured by the 2D-Video distrometer(2DVD) by comparing two cases which are heavy rainfall event case and a case that is not classified as heavy rainfall but having more than $30mm\;h^{-1}$ rainrate in July, 2014 at Gimhae region. As a results; Over the high pressure edge area where strong upward motion exists, the convective rain type occurred and near the changma front, convective and frontal rainfall combined rain type occurred. Therefore, rainrate varies based on the synoptic meteorological condition. The most rain drop distribution appeared in the raindrops with diameters between 0.4 mm and 0.6 mm and large particles appeared for the convective rain type since strong upward motion provide favorable conditions for the drops to grow by colliding and merging so the drop size distribution varies based on the location or rainfall types. The rainfall phases is mainly rain and as the diameter of the raindrop increase the fall velocity increase and oblateness decrease. The equation proposed based on the 2DVD tends to underestimated both fall velocity and oblateness compared with observation. Since these varies based on the rainfall characteristics of the observation location, standard equation for fall velocity and oblateness fit for Gimhae area can be developed by continuous observation and data collection hereafter.

• 한국환경과학회지
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• 제19권3호
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• pp.353-363
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• 2010

The most efficient measures to reduce damage from natural disasters include activities which prevent disasters in advance, decrease possibility of disasters and minimize the scale of damage. Therefore, developing of the risk assessment model is very important to reduce the natural disaster damage. This study estimated a typhoon damage which is the biggest damage scale among increased natural disasters in Korea along with climate change. The results of 3-second gust at the height of 10m level from the typhoon 'Maemi' which did considerable damage to Korean in 2003, using the wind data at the height of 700 hPa. September 12th 09 LST~13th 12 LST period by the time a typhoon Maemi approached to the Korean peninsula. This study estimate damage amount using 'Fragility curve' which is the damage probability curve about a certain wind speed of the each building component factors based on wind load estimation results by using 3-second gust. But the fragility curve is not to Korea. Therefore, we use the fragility curves to FPHLM(FDFS, 2005). The result of houses damage amount is about 11 trillion 5 million won. This values are limit the 1-story detached dwelling, $62.51\sim95.56\;m^2$ of total area. Therefore, this process is possible application to other type houses.

• 한국환경과학회지
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• 제23권1호
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• pp.25-37
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• 2014

In the present study, we analyzed precipitation patterns and diurnal variation trends of hourly precipitation intensity due to climate change. To that end, we used the hourly precipitation data obtained from 26 weather stations around South Korea, especially Busan, from 1970 to 2009. The results showed that the hourly precipitation was concentrated on a specific time of day. In particular, the results showed the so-called "morning shift" phenomenon, which is an increase in the frequency and intensity of hourly precipitation during the morning. The morning shift phenomenon was even more pronounced when a higher level of hourly precipitation intensity occurred throughout the day. Furthermore, in many regions of Korea, including Busan, this morning shift phenomenon became more prevalent as climate change progressed.

• Journal of Korean Society for Atmospheric Environment
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• 제22권E2호
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• pp.57-68
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• 2006

Four intensive seasonal sampling campaigns between October 1998 and October 1999 were undertaken at an urban site of Chongju, in which polyurethane foam (PUF) sampler was used to collect particulate- and vapor-phase polycyclic aromatic hydrocarbons (PAHs). The contribution to total (particulate+vapor) PAH concentration by the vapor phase component exceeded the particulate phase contribution by factor of ${\sim}2.6$. Summed concentrations of phenanthrene (30.9%), pyrene (16.6%), naphthalene (11.3%) and fluoranthene (11.0%) account for significant amounts of the vapor-phase, while chrysene (12.5%), benzo[b]fluoranthene (11.6%), indeno[123-cd]pyrene (9.9%), benzo[ghi]perylene (9.5%), benzo[k]fluoranthene (9.4%), pyrene (8.9%), and benzo[a]pyrene (8.3%) are found to be the most common PAH compounds in the particulate phase. The results from application of principal component analysis to particulate-phase PAH data demonstrate that a combination of PAH and $PM_{2.5}$ inorganic data is a more powerful tracer of emission sources than PAH species data alone. Particulate-phase PAH species were found to be associated predominantly with emissions from diesel engine vehicles and incineration.

• Asian Journal of Atmospheric Environment
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• 제9권1호
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• pp.12-21
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• 2015

Air pollution is a challenging issue in some of the large cities in developing countries. In this regard, data interpretation is one of the most important parts of air quality management. Several methods exist to analyze air quality; among these, we applied the Multilayer Perceptron (MLP) and Radial Basis Function (RBF) methods to predict the hourly air concentration of benzene in 14 districts in the municipality of Tehran. Input data were hourly temperature, wind speed and relative humidity. Both methods determined reliable results. However, the RBF neural network performance was much closer to observed benzene data than the MLP neural network. The correlation determination resulted in 0.868 for MLP and 0.907 for RBF, while the Index of Agreement (IA) was 0.889 for MLP and 0.937 for RBF. The sensitivity analysis related to the MLP neural network indicated that the temperature had the greatest effect on prediction of benzene in comparison with the wind speed and humidity in the study area. The temperature was the most significant factor in benzene production because benzene is a volatile liquid.

• Asian Journal of Atmospheric Environment
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• 제12권3호
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• pp.244-254
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• 2018

Ulaanbaatar, the capital of Mongolia, is subject to high levels of atmospheric pollution during winter, which severely threatens the health of the population. By analyzing surface meteorological data, ground-based LIDAR data, and radiosonde data collected from 2008 to 2016, we studied seasonal variations in particulate matter (PM) concentration, visibility, relative humidity, temperature inversion layer thickness, and temperature inversion intensity. PM concentrations started to exceed the 24-h average standard ($50{\mu}g/m^3$) in mid-October and peaked from December to January. Visibility showed a significant negative correlation with PM concentration. Relative humidity was within the range of 60-80% when there were high PM concentrations. Both temperature inversion layer thickness and intensity reached maxima in January and showed similar seasonal variations with respect to PM concentration. The monthly average temperature inversion intensity showed a strong positive correlation with the monthly average $PM_{2.5}$ concentration. Furthermore, the temperature inversion layer thickness exceeded 500 m in midwinter and overlaid the weak mixed layer during daytime. Radiative cooling enhanced by the basin-like terrain led to a stable urban atmosphere, which strengthened particulate air pollution.

• 한국대기환경학회지
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• 제28권2호
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• pp.159-171
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• 2012

Aerosol direct radiative forcing (ADRF) retrieval method was developed by combining data from passive and active satellite sensors. Aerosol optical thickness (AOT) retrieved form the Moderate Resolution Imaging Spectroradiometer (MODIS) as a passive visible sensor and aerosol vertical profile from to the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) as an active laser sensor were investigated an application possibility. Especially, space-born Light Detection and Ranging (Lidar) observation provides a specific knowledge of the optical properties of atmospheric aerosols with spatial, temporal, vertical, and spectral resolutions. On the basis of extensive radiative transfer modeling, it is demonstrated that the use of the aerosol vertical profiles is sensitive to the estimation of ADRF. Throughout the investigation of relationship between aerosol height and ADRF, mean change rates of ADRF per increasing of 1 km aerosol height are smaller at surface than top-of-atmosphere (TOA). As a case study, satellite data for the Asian dust day of March 31, 2007 were used to estimate ADRF. Resulting ADRF values were compared with those retrieved independently from MODIS only data. The absolute difference values are 1.27% at surface level and 4.73% at top of atmosphere (TOA).