• Atmosphere
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• v.17 no.4
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• pp.435-453
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• 2007

KEOP (Korea Enhanced Observing Period)-2004 intensive summer observation was carried out from 20 June to 5 July 2004 over the Southwestern part of the Korean peninsula. In this study, the effects of KEOP-2004 intensive observation data on the simulation of precipitation system are investigated using KLAPS (Korea Local Analysis and Prediction System) and PSU/NCAR MM5. Three precipitation cases during the intensive observation are selected for detailed analysis. In addition to the control experiments using the traditional data for its initial and boundary conditions, two sensitivity experiments using KEOP data with and without Jindo radar are performed. Although it is hard to find a clear and consistent improvement in the verification score (threat score), it is found that the KEOP data play a role in improving the position and intensity of the simulated precipitation system. The experiments started at 00 and 12 UTC show more positive effect than those of 06 and 18 UTC. The effect of Jindo radar is dependent on the case. It plays a significant role in the heavy rain cases related to a mesoscale low over Changma front and the landing of a Typhoon. KEOP data produce more strong difference in the 06/18 UTC experiments than in 00/12 UTC, but give more positive effects in 00/12 UTC experiments. One of the possible explanations for this is that : KEOP data could properly correct the atmosphere around them when there are certain amounts of data, while gives excessive effect to the atmospheric field when there are few data. CRA analysis supports this reasoning. According to the CRA (Contiguous Rain Area) analysis, KEOP data in 00/12 UTC experiments improve only the surrounding area, resulting in essentially same precipitation system so the effects remain only in each convective cell rather than the system itself. On the other hand, KEOP data modify the precipitation system itself in 06/18 UTC experiments. Therefore the effects become amplified with time integration.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.23-32
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• 2015

This paper addresses the effects of extreme rainfall on the stability of cut slopes in Yen Bai city, Northern Viet Nam. In this area, natural slopes are excavated to create places for infrastructures and buildings. Cut slopes are usually made without proper site investigations; the design is mostly based on experience. In recent years, many slope failures have occurred along these cuts especially in rainy seasons, resulting in properties damaged and loss of lives. To explain the reason that slope failure often happens during rainy seasons, this research analyzed the influence of extreme rainfalls, initial ground conditions, and soil permeability on the changes of pore water pressure within the typical slope, thereafter determining the impact of these changes on the slope stability factor of safety. The extreme rainfalls were selected based on all of the rainfalls triggering landslide events that have occurred over the period from 1960 to 2009. The factor of safety (FS) was calculated using Bishop's simplified method. The results show that when the maximum infiltration capacity of the slope top soil is less than the rainfall intensity, slope failures may occur 14 hours after the rain starts. And when this happens, the rainfall duration is the deciding factor that affects the slope FS values. In short, cut slopes in Yen Bai may be stable in normal conditions after the excavation, but under the influence of tropical rain storms, their stability is always questionable.

• Journal of the Korean earth science society
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• v.18 no.6
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• pp.565-578
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• 1997

Clouds are usually formed by adiabatic cooling through ascending currents, radiation cooling or a mixture of warm air and cold one. Ascending currents are caused by covection currents, or they are accompanied with fronts. Thus clouds are formed through various kinds of causes and procedures. So they are various in height and shape. Form of clouds was classified on the basis of the thecriteria that L. Howard proposed in 1803. He distinguished three simple, fundamental classes-Cirrus, Cumulus, Stratus-from which the others were derived by trasition or association. And they are subdivided into 10 genera according to their height and shape. Most of the clouds are subdivided into the detailed kinds to the characteristics such as appearance or intensity of convection current. Sometimes completly different shape of cloud can be developed out of the 'mother-cloud'. In korea, the stratocumulus, altostratus and cirrus clouds frequently appear. Generally we are likely to have rain or snow from the stratus cloud forms(As, St, Sc) and rain shower or hail from the cumulus forms(Ac, Cu, Cb).

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.473-486
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• 2001

The WGR model was developed to represent meso-scale precipitation. As a conceptual model, this model shows a good link between atmospheric dynamics and statistical description of meso-scale precipitation(Waymire et al., 1984). However, as it has maximum 18 parameters along with its non-linear structure, its parameter estimation has been remained a difficult problem. There have been several cases of its parameter estimation for different fields using non-linear programming techniques(NLP), which were also difficult tasks to hamper its wide applications. In this study, we estimated the WGR model parameters of the Han river basin using the genetic algorithm(GA) and compared them to the NLP results(Yoo and Kwon, 2000). As a result of the study, we can find that the sum of square error from the GA provide more consistent parameters to the seasonal variation of rainfall. Also, we can find that the higher rainfall amount during summer season is closely related with the arrival rate of rain bands, not the rain cell intensity.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.545-554
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• 2007

This study characterized the storm events recorded in the Annals of Chosun Dynasty and evaluated them using a simple rectangular pulses Poisson process model. Storm events without in detail explanation like Keun-Bi (big rain) were found to have rather short return periods compared to the storm events with lengthy explanation about damages like Keun-Mul (high water), Hong-Soo (flood), and Pok-Woo (torrential rain). Not all storm events recorded were the size of annual maxima, so their return periods were found not to be higher than a certain level. Another noticeable fact is that these storm events recorded seem more sensitive to the storm duration rather than the storm intensity. That is, most storms recorded seem to be focused on long durations rather than high intensities. Those storm events with long durations must have caused serious flood damages, which maybe the critical reason why they were recorded.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.154-163
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• 2018

Not only South Korea but also Global world show that the frequency and damages of large-scale natural disaster due to the rise of heavy rain event and typhoon or hurricane intensity are increasing. Natural disasters such as typhoon, flood, heavy rain, strong wind, wind wave, tidal wave, tide, heavy snow, drought, earthquake, yellow dust and so on, are difficult to estimate the scale of damage and spot. Also, there are many difficulties to take action because natural disasters don't appear precursor phenomena However, if scale of damage can be estimated, damages would be mitigated through the initial damage action. In the present study, therefore, wind wave damage estimation functions for the western coastal zone are developed based on annual disaster reports which were published by the Ministry of Public Safety and Security. The wind wave damage estimation functions were distinguished by regional groups and facilities and NRMSE (Normalized Root Mean Square Error) was analyzed from 1.94% to 26.07%. The damage could be mitigated if scale of damage can be estimated through developed functions and the proper response is taken.

• KCID journal
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• v.14 no.1
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• pp.57-66
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• 2007

Temporal changes in total nitrogen (T-N) and phosphorus (T-P) concentrations in paddy floodwater in response to fertilization under rain-shielding pot and small-scaled field conditions were investigated. On the basis of the changing patterns, suggestions for the use of fertilization factors, such as days after fertilization, in developing models for the estimation of T-N and T-P loads from paddy fields were made. Total N concentration was susceptible to fertilization, showing a peak concentration right after fertilization followed by a decreasing pattern with the elapse of days after fertilization. The decreasing pattern of T-N concentration followed the first- order kinetics, indicating that the models are likely to be an exponential equation using days after fertilization as an independent variable. Comparison between the pot and field experiments conducted with soils different in soil fertility revealed that indigenous soil N concentration significantly affected T-N concentration, and this suggests that soil N status can be used as the second variable for the models. Meanwhile, temporal changes in T-P concentration did not respond to P fertilization as sensitively as T-N. In combination with other published results, our study suggests that rainfall intensity and other factors associated with farming activities that are likely to cause disturbance of soil particles containing P may be used as possible variables for the models.

• Journal of Korea Water Resources Association
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• v.39 no.6 s.167
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• pp.521-531
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• 2006

The formula was proposed through the examination of probability rainfall intensity formula used in Incheon based upon recent occurrences of heavy rain and extraordinary storms. Random-time maximum annual rainfalls were estimated for durations from ten minutes to twenty-four hours from the data by Korea Meteorological Administration. Eleven types of probability distribution are considered to estimate probable rainfall depths for different storm durations at Incheon city. Three goodness-of-fit tests including Chi-square, Kolmogorov-Smirmov and framer Von Misses were used to analyze the tendency of recent rainfall. Considering maximum rainfall occurred, General Extreme Value(GEV) distribution was chosen as the appropriate probability distribution. Five types of probability rainfall formulas including Talbot type, Sherman type, Japanese type, unified type I and unified type II are considered to determine the best type for rainfall intensity at Incheon. The formula was determined considering the time of concentration of sewer system and river at Incheon city. Unified type I was chosen for its accuracy and was proposed to represent rainfall intensity of Incheon district.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.4
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• pp.130-145
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• 2016

Soil erosion processes are affected by weather factors, such as rainfall, temperature, wind, and humidity. Among these factors, rainfall directly influences soil erosion by breaking away soil particles. The kinetic energy of rainfall and water flow caused by rain entrains and transports soil particles downstream. Therefore, in order to estimate soil erosion, it is important to accurately determine the rainfall erosivity factor(R) in RUSLE(Revised Universal Soil Loss Equation). The objective of this study is to evaluate the average annual R using 14 years(2002~2015) of 1 minute rainfall data from 55 KMA(Korea Meteorological Administration) weather stations. The R results from 1 min rainfall were compared with previous R studies using 1 h rainfall data. The determination coefficients($R^2$) between R calculated using 1 min rainfall data and annual rainfall were 0.70-0.98. The estimation of 30 min rainfall intensity from 1 min rainfall data showed better $R^2$ results than results from 1 h rainfall data. For estimation of physical spatial rain erosivity(R), distribution of annual rainfall was estimated by IDW(Inverse Distance Weights) interpolation, taking elevation into consideration. Because of the computation burden, the R calculation process was programmed using the python GUI(Graphical User Interface) tool.

• Journal of Environmental Science International
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• v.5 no.5
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• pp.663-676
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• 1996

The analyzed results of observed precipitation and its pH in Kwangiu for 262 days from fan. 1, 1991 to Dec. 31, 1995 are as follows. The annual mean pH was 5.7, and the monthly mean pH values of January-May and November were less than 5.6 in Kwangiu. The ratio of acid rain for these periods was about 48.1%, almost half that of the total observed days. In March, the pH was 5.4 and the ratio of acid precipitation was 69%, an especially serious situation. In the spring, the pH value was 5.5, thus weakly acidic. The pH of precipitation tended to decrease with greater precipitation. The relation between persistent time and pH of precipitation is variable, but if the persistent time is long, the pH is constant and low. It is fortunate that there is an increasing trend of pH in interannual variation, but it is thought important that the amplitude of variation of pH in 1995 was high and the pH value was 4.1 in October and November. Because heavy and persistent precipitation effects the accumulation of acidity, more concern about acid rain is needed.