• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.4
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• pp.42-52
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• 1985

This study was attempted to derivate empirical formulas for the runoff: ratio during ilood. season at three watersheds of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle, and lower portion of Nam Han river basin, respectively. Obtained formulas for flood runoff ratio can be applied as an element for the estimation, peak discharge for the design of various hydraulics structures which can be concidented with meteorological and topographical condition. The obtained through this study were analyzed as follows. 1.It was found that the magnitude of runoff ratio depends on the amount of rainfall for all studying basins. 2.Empirical formulas 'for the runoff' ratio were derivated as 1- 2,707 Rt0.345, 1-1.691 Rt0.242 and 1-1.807 Rt0.227 at Dan Yang, Chung Ju and Yeo Ju watershed, respectively. 3.The magnitude of runoff ratio was appeared in the order of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle and lower portion of Nam Han rivet basin, respectively. 4.It was assumed that in general the more it rains, the lesser becomes the ratio of loss rainfall. Especially, the ratio of loss rainfall for Dan Yang, upper portion of river basin was shown as the lowest among three watersheds. Besides, the magnitude of that was appeared in the order of Chung Ju and Yeo Ju watershed located at middle, and lower part of river basin, respectively. 5.Relative and standard errors of runoff ratio calculated by empirical formulas were shown to be within ten percent to the observed runoff ratio in all watersheds. 6.It is urgently essential that the effect of antecedent rainfall have an influence on the next coming flood should be studied in near future.

• Atmosphere
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• v.25 no.3
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• pp.529-541
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• 2015

Korea Institute of Atmospheric Prediction System (KIAPS) has been developing a global numerial prediction model and data assimilation system. We has implemented LETKF (Local Ensemble Transform Kalman Filter, Hunt et al., 2007) data assimilation system to NCAR CAM-SE (National Center for Atmospheric Research Community Atmosphere Model with Spectral Element dynamical core, Dennis et al., 2012) that has cubed-sphere grid, known as the same grid system of KIAPS Integrated Model (KIM) now developing. In this study, we have assimilated Global Positioning System Radio Occultation (GPS-RO) bending angle measurements in addition to conventional data within ensemble-based data assimilation system. Before assimilating bending angle data, we performed a vertical unit conversion. The information of vertical localization for GPS-RO data is given by the unit of meter, but the vertical localization method in the LETKF system is based on pressure unit. Therefore, with a clever conversion of the vertical information, we have conducted experiments to search for the best vertical localization scale on GPS-RO data under the Observing System Simulation Experiments (OSSEs). As a result, we found the optimal setting of vertical localization for the GPS-RO bending angle data assimilation. We plan to apply the selected localization strategy to the LETKF system implemented to KIM which is expected to give better analysis of GPS-RO data assimilation due to much higher model top.

• Atmosphere
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• v.21 no.1
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• pp.123-130
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• 2011

In this study, we have analyzed the radiative characteristics of erythemal ultraviolet-B (EUV-B from 1999 to 2005) over the Korean Peninsula. EUV-B measured at Gangneung, Anmyondo, Mokpo, and Gosan represents the measurements from clean areas and that at Seoul represents from a polluted area. The magnitudes of EUV-B increase in proportion to the latitudinal decrease. Monthly mean variation of EUV-B at noon shows the maximum value of $158.5mWm^{-2}$ in August and the minimum value of $36.4mWm^{-2}$ in December in the clean areas. Seasonal mean diurnal variation of EUV-B shows a peak around noon (12:00 ~ 13:00 hr) and its intensity varies along with a season in order of summer > spring > fall > winter. The maximum value of $56.4mWm^{-2}$ in summer is three times higher than that in winter ($14.3mWm^{-2}$). The value of EUV-B in the polluted area is lower than that in the clean areas, resulting from the effects of the blocking, reflection, and scattering of EUV-B due to high concentrations of PM10. UV-B is an essential element to synthesize vitamin D in human body. 200 IU(International Unite) of vitamin D can be formed by an exposure of 6-10% of body surface area to 0.5 MED(Minimal Erythemal Dose). In order to form vitamin D, the calculated exposure times to EUV-B are 15 min. in spring, 12 min. in summer, 18 min. in fall, and 37 min. in winter for the clean areas and 16, 16, 24, and 37 min. for the polluted area.

• Smart Structures and Systems
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• v.26 no.3
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• pp.291-309
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• 2020

To study oceanic and meteorological problems related to climate change, Korea has been operating several ocean research stations (ORSs). In 2011, the Gageocho ORS was attacked by Typhoon Muifa, and its structural members and several observation devices were severely damaged. After this event, the Gageocho ORS was rehabilitated with 5 m height to account for 100-yr extreme wave height, and the vibration measurement system was equipped to monitor the structural vibrational characteristics including natural frequencies and modal damping ratios. In this study, a mass reallocation method is presented for structural model updating of the Gageocho ORS based on the experimentally identified natural frequencies. A preliminary finite element (FE) model was constructed based on design drawings, and several of the candidate baseline FE models were manually built, taking into account the different structural conditions such as corroded thickness. Among these candidate baseline FE models, the most reasonable baseline FE model was selected by comparing the differences between the identified and calculated natural frequencies; the most suitable baseline FE model was updated based on the identified modal properties, and by using the pattern search method, which is one of direct search optimization methods. The mass reallocation method is newly proposed as a means to determine the equivalent mass quantities along the height and in a floor. It was found that the natural frequencies calculated based on the updated FE model was very close to the identified natural frequencies. In conclusion, it is expected that these results, which were obtained by updating a baseline FE model, can be useful for establishing the reference database for jacket-type offshore structures, and assessing the structural integrity of the Gageocho ORS.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.12
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• pp.467-476
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• 2016

As the energy saving issues become one of the important global agenda, the building simulation method is generally used to predict the inside energy usage to establish the power-saving strategies. To foretell an accurate energy usage of a building, proper and typical weather data are needed. For this reason, typical weather data are fundamental in building energy simulations and among the meteorological factors, the solar irradiation is the most important element. Therefore, preparing solar irradiation is a basic factor. However, there are few places where the horizontal solar radiation in domestic weather stations can be measured, so the prediction of the solar radiation is needed to arrive at typical weather data. In this paper, four solar radiation prediction models were analyzed in terms of their applicability for domestic weather conditions. A total of 12 regions were analyzed to compare the differences of solar irradiation between measurements and the prediction results. The applicability of the solar irradiation prediction model for a certain region was determined by the comparisons. The results were that the Zhang and Huang model showed the highest accuracy (Rad 0.87~0.80) in most of the analyzed regions. The Kasten model which utilizes a simple regression equation exhibited the second-highest accuracy. The Angstrom-Prescott model is easily used, also by employing a plain regression equation Lastly, the Winslow model which is known for predicting global horizontal solar irradiation at any climate regions uses a daily integration equation and showed a low accuracy regarding the domestic climate conditions in Korea.

• Convergence Security Journal
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• v.11 no.5
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• pp.109-120
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• 2011

How meteorological situations have affected human life for survival have been an important element of living or military strategy throughout history. In modern society, overcrowding of cities has brought about many problems. Moreover, high-rise buildings and land cover have been causing abnormal weather conditions. The wind corridor, especially in urban areas has been flowing differently from the dominant weather condition of the surroundings. Therefore, the wind corridor in urban areas can be a main component in protecting major national facilities in urban areas from damage. Especially the wind corridor is a main factor to derive harm from poisonous substances in air. This paper seeks to find out the wind corridor in urban areas and the efficiency of that. In addition to that, it studies how to use the direction to protect major national facilities and areas from damage. It is considered that this study will be useful to make defence project, not only for preventing CBR(chemical, biological, and radiological) terrorism and violent assembly, but also for evacuation of people in case of big accidents or natural disasters.

• Korean Journal of Remote Sensing
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• v.14 no.1
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• pp.1-16
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• 1998

Microwave brightness temperature data measured from the Special Sensor Microwave/Imager (SSM/I) aboard Defense Meteorological Satellite Program (DMSP) satellite are used to investigate the characteristics of hydrological features of the East Asian summer monsoon during 1994 and 1995. The analyzed parameters include total columnar water vapor, cloud liquid water, and rain rate. These are estimated from SSM/I brightness temperature data for the two summer seasons (June, July, August) of 1994 and 1995 over the Asian monsoon region (0$^{\circ}$-60$^{\circ}$N, 45$^{\circ}$-180$^{\circ}$E). Results indicate that there are periodic westward movement of dry air over the 20$^{\circ}$-30$^{\circ}$N latitudinal belt with about 20-30 day period. Considering that the location of the North Pacific high is closely linked to the evolution of the monsoon activities over East Asia, the westward expansion of the North Pacific high may be the one important element modulating the monsoon intensity.

• Journal of the Korean earth science society
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• v.31 no.3
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• pp.234-245
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• 2010

Twenty-four hour integrated $PM_{10}$ and $PM_{2.5}$ samples were measured during springtime (March, April, and May) in Busan for three years from 2006 to 2008, and mass concentrations and metallic elements of measurement were analyzed to investigate temporal, spatial, chemical characteristics of the mass concentration and metallic elements in association with meteorological conditions including Asian Dust (AD) vs. non Asian Dust (NAD) seasons, and other air mass transport patterns. The result showed that $PM_{10}$, $PM_{2.5}$ and $PM_{10-2.5}$ concentrations were on average of $126.2{\pm}89.8$, $85.5{\pm}41.6$, and $40.7{\pm}54.9{\mu}g/m^3$, respectively, and the $PM_{2.5}/PM_{10}$ and $PM_{10-2.5}/PM_{2.5}$ ratios were 0.70 and 0.48, respectively. The highest concentrations of PM were observed when air parcels were originated from both northwest sector covering Beijing and west sector including Shanghai areas.

• Journal of Korea Water Resources Association
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• v.53 no.10
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• pp.903-915
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• 2020

Long-term high-resolution hydro-meteorological data has been recognized as an essential element in establishing the water resources plan. The increasing demand for spatial precipitation in various areas such as climate, hydrology, geography, ecology, and environment is apparent. However, potential limitations of the existing area-weighted and numerical interpolation methods for interpolating precipitation in high altitude areas remains less explored. The proposed PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) model can produce gridded precipitation that can adequately consider topographic characteristics (e.g., slope and altitude), which are not substantially included in the existing interpolation techniques. In this study, the PRISM model was optimized with SCEM-UA (Shuffled Complex Evolution Metropolis-University of Arizona) to produce daily gridded precipitation. As a result, the minimum impact radius was calculated 9.10 km and the maximum 34.99 km. The altitude of coastal weighted was 681.03 m, the minimum and maximum distances from coastal were 9.85 km and 38.05 km. The distance weighting factor was calculated to be about 0.87, confirming that the PRISM result was very sensitive to distance. The results showed that the proposed PRISM model could reproduce the observed statistical properties reasonably well.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1049-1058
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• 2004

PM10 concentration of total 48 samples collected from 4 sites (the root of Miryang University, Sangnam township Office in Miryang. the root of Changwon elementary school, and Junam reservoir in Changwon) turned out to range from 42.29 to 69.49{\mu}g/m^{3}$, and the average concentration was the root of Changwon elementary school $(69.49{\mu}g/m^{3})$>the root of Miryang university $(58.59{\mu}g/m^{3})$>Junam reservoir $(43.56{\mu}g/m^{3})$>Sangnam township Office $(42.29{\mu}g/m^{3}).> In particular, Junam reservoir, the Clean Area, had a slightly higher value than Sangnam township Office. It was thought although the site was plane and windy without pollutants around. it had a higher concentration value influenced by external factors including bigger population and a northeasterly wind due to a newly-established industrial complex nearby. As for water-soluble ions among PM10 particle collected in Miryang and Changwon area, SO42- accounted for $50{/%}$ and NO3-, was $35{\%}$, and the concentration order was S042->N03->Cl->F-. As for the average concentration of metallic components among PM10 particle collected in Miryang and Changwon area. the root of Changwon elementary school had the AI concentration, Fe concentration and Zn concentration 4 times, 3 times and 1.5 times that of Junam reservoir, respectively. The root of Miryang University had the AI concentration 2 times that of Sangnam township Office, and had Fe concentration and Zn concentration $1.2\~1.5$ times those of Sangnam township Office. When it comes to the relation between metallic elements and meteorological factors in Changwon area, the highest coefficient of correlation was between temperature and humidity with 0.92, and temperature and wind speed turned out in the reverse correlation. The coefficient of correlation between Al and Cr was as high as 0.78. Among metallic elements, the coefficient of correlation between Cu and Pb, Cd, Al were 0.84, 0.85, 0.79, respectively. It is thought that the high coefficient of correlation between Cu and Pb is ascribed to busy traffic and wind in the urban areas, Sammun-dong and Gagok-dong in Miryang. Meanwhile, the coefficients of correlation between Fe and Cu, Al, Zn, Cd, Pb were in the reverse correlation. These coefficients of correlation are attributed to the difference in pollutant sources, rather than difference in pollutant and non-pollutant.