• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.135-135
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• 2021

In water resources management, rainfall prediction with high accuracy is still one of controversial issues particularly in countries facing heavy rainfall during wet seasons in the monsoon climate. The aim of this study is to develop an artificial neural network (ANN) for predicting future six months of rainfall data (from April to September 2020) from daily meteorological data (from 1971 to 2019) such as rainfall, temperature, wind speed, and humidity at Seoul, Korea. After normalizing these data, they were trained by using a multilayer perceptron (MLP) as a class of the feedforward ANN with 15,000 neurons. The results show that the proposed method can analyze the relation between meteorological datasets properly and predict rainfall data for future six months in 2020, with an overall accuracy over almost 70% and a root mean square error of 0.0098. This study demonstrates the possibility and potential of MLP's applications to predict future daily rainfall patterns, essential for managing flood risks and protecting water resources.

• Korean Journal of Remote Sensing
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• v.30 no.4
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• pp.465-480
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• 2014

In this study, we analyzed the spatio-temporal variations of satellite imagery for the two heavy rainfall cases (21 September, 2010, 9 August, 2011) occurred in the Korean Peninsula. In general, the possibility of strong convection can be increased when the region with plenty of moisture at the lower layer overlapped with the boundary between dark and bright area in the water vapor imagery. And the merging of convective cells caused by the difference in the moving velocities of two cells resulted in the intensification of convective activity and rainfall intensity. The rainfall intensity is more closely linked with the minimum cloud top temperature than the mean cloud top temperature. Also the spatio-temporal variations of rainfall intensity are impacted by the existence of merging processes. The merging can be predicted by the animation of satellite imagery but earlier detection of convective cells is almost impossible by using the infrared and water vapor imagery.

• Atmosphere
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• v.26 no.1
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• pp.159-183
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• 2016

On 31 July 2014, there was a localized torrential rainfall ($58.5mm\;hr^{-1}$) caused by a strong convective cell with thunder showers over Daegwallyeong. In the surface synoptic chart, a typhoon was positioned in the East China Sea and the subtropical high was expanded to the Korean peninsula. A WRF (Weather Research and Forecasting) numerical simulation with a resolution of 1 km was performed for a detailed analysis. The simulation result showed a similar pattern in a reflectivity distribution particularly over the Gangwon-do region, compared with the radar reflectivity. According to the results of the WRF simulation, the process and mechanism of the localized heavy rainfall over Daegwallyeong are as follows: (1) a convective instability over the middle part of the Korean peninsula was enhanced due to the low level advection of warm and humid air from the North Pacific high. (2) There was easterly flow from the coast to the mountainous regions around Daegwallyeong, which was generated by the differential heating of the insolation among Daegwallyeong and the Yeongdong coastal plain, and nearby coastal waters. (3) In addition, westerly flow from the western part of Daegwallyeong caused a strong convergence in this region, generating a strong upward motion combined by an orographic effect. (4) This brought about a new convective cell over Daegwallyeong. And this cell was more developed by the outflow from another thunderstorm cell to the south, and finally these two cells were merged to develop as a strong convective cell with thunder showers, leading to the record breaking maximum rainfall per hour ($58.5mm\;hr^{-1}$) in July.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1386-1394
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• 2008

The slope-related disasters in Korea usually occur between July and September during the typhoon and localized heavy rain. This means that the rainfall is the most important factor that leads to the slope-related disasters. The slope-related disasters can happen at very short time and lead to big damage. To forecast the change of the heave of the groundwater in slope the Seep/w program was used.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.161-170
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• 2010

This paper is results of analyzing causes of damage and rainfall characteristics to investigate characteristics of landslide occurrence and its causes at Inje area in Gangwondo around July in 2006 through collection of related data, literature review and field reconnaissance. From results of analyzing the geometrical characteristics of landslide slope, the slope width of showing the most probable frequency were in the range of 10~50m and the most frequent slope angle was in the range of $30{\sim}40^{\circ}$. The most probable elevation of slope was 200~300m. For the slope direction of landslides, the most frequent directions were NW and SE.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1001-1006
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• 2004

Railroad disasters are frequently occurred by man-made causes or natural causes. In general, man-made causes are illegal construction practices, deterioration with the lapse of time and railroad crossing accidents, and natural causes are rainfall. snow, wind, earthquake, etc. Of cause, railroad disasters by man-made causes are prevented from keeping the safety principle, constructing multi-level crossing, securing enough men of ability and financial resources and making a thorough check using equipments with high capacity. And railroad disasters by natural causes are also minimized by construction of disaster prevention facilities, introduction and operation of general disaster prevention system and reasonable train passage control. Therefore, to setup the criterion of train passage control for train safety at railroad bridge under heavy rainfall, risky factors, national and oversea criteria under such circumstances are reviewed and a scheme to setup the criterion is suggested.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1041-1050
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• 2009

Many slope failures and debris flows were occurred in Jinbu area of Gangwon Province due to heavy rainfall of much more than 400mm in July, 2006. In the area, although about 3 years passed, valleys and gulleys keep their original form when the events happened. Field investigations were performed on Singi-ri and Bongsan-ri in Jinbu area to examine the characteristics of debris flow as well as slope failure. As the result, debris flows were classified as 3 types according to their characteristics analyzed by field investigations.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.95-101
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• 2010

This paper is results of case study on characteristics of debris flow occurred at Jecheon during a heavy rainfall in 2009. The site studied is the mountain area located at Palsong-ri Bongyang-op in Jecheon-si where serious damages due to debris flow were occurred by heavy rainfall during July 7 to July 16 in 2009. Intensity and duration of rainfall causing debris flow were analyzed on the basis of AWS data. Characteristics of debris flow such as initiation, transportation and deposition were investigated through field reconnaissance. The geological and topographical characteristics of slope where debris flow was triggered were figured out and characteristics of erosion on the bottom and sides of valley during transportation of debris flow were also investigated. The slope and boundary of valley where the debris flow started to be deposited were studied.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1252-1254
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• 2003

Debris flows associated with landslides occur as one of the most devastating natural disasters that threat Taiwan. Typically, three essential factors are needed simultaneously to trigger debris flow, namely sufficient soils and rocks, favorable slope, and abundant water. Among the three essentials, the slope is natural and static without external forcing, while the landslide is generally induced by earthquake or rainfall events, and the water is produced by heavy rainfall events. In this study, we analyzed the landslides triggered by the typhoons Herb (1996) and typhoon Troaji (2001). It is concluded that the statistical data are useful to quantify the threshold of the potential landslide area. Then, the possibility to prevent the debris flow occurrence may be increased.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.553-560
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• 2014

The rainfall-runoff characteristics in Jeju Island significantly differ from those in inland, due to highly permeable geologic features driven by volcanic island. Streams are usually sustained in the dry conditions and thereby the rainfall-runoff characteristics changes in terms of initiating stream discharge and its types, depending highly on the antecedent precipitation. Among various the rainfall-runoff characteristics, lag time mainly used for flood warning system in river and direct runoff ratio for determining water budget to estimate groundwater recharge quantity are practically crucial. They are expected to vary accordingly with the given antecedent precipitation. This study assessed the lag time in the measured hydrograph and direct runoff ratio, which are especially in the upstream watershed having the outlet as $2^{nd}$ Dongsan bridge of Han stream, Jeju, based upon several typhoon events such as Khanun, Bolaven, Tembin, Sanba as well as a specific heavy rainfall event in August 23, 2012. As results, considering that the lag time changed a bit over the rainfall events, the averaged lag time without antecedent precipitation was around 1.5 hour, but it became increased with antecedent precipitation. Though the direct run-off ratio showed similar percentages (i.e., 23%)without antecedent precipitation, it was substantially increased up to around 45% when antecedent precipitation existed. In addition, the direct run-off ration without antecedent precipitation was also very high (43.8%), especially when there was extremely heavy rainfall event in the more than five hundreds return period such as typhoon Sanba.