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Wansik Yu,Eiichi Nakakita,Kosei Yamaguchi,정관수 충북연구원 2016 지역정책연구 Vol.27 No.1
In early September, 2011, local heavy rainfalls due to season’s 12th typhoon, “Talas” caused large flooding and enormous landslide disasters over the Kinki, Chugobku, Shikoku, and 16 missing persons. In these types of extreme events, it is essential to be able to provide as much advance warning as possible. This advance warning requires both quantitative precipitation forecasting (QPF) and quantitative flood forecasting (QFF). In this study, we assessed the ensemble NWP rainfall with 2km horizontal resolution and 30hr forecast time whether it can produce suitable rainfall or not. This study also proposes pre-processing methodology with a spatial shift of ensemble NWP rainfall fields, in order to improve the accuracy of the ensemble flood forecasting. Our study is carried out and verified using the largest flood event by typhoon ‘Talas’ of 2011 over the two catchmetns, which are Futatsuno (356.1㎢) dam catchments of Shingu river basin (2,360㎢), which is located in the Kii peninsula, Japan.
Application of an X-Band Multiparameter Radar Network for Rain-Based Urban Flood Forecasting
Yoon, Seong-Sim,Nakakita, Eiichi American Society of Civil Engineers 2017 Journal of hydrologic engineering Vol.22 No.5
<P>Urban floods can occur immediately after heavy rainfall depending on the characteristics of the urban environment. Therefore, earlier warnings, even by 5-10min, are crucial in terms of human safety. In this case study, an X-band multiparameter (X-MP) radar network, which has a 1-min temporal and 250-m spatial resolution, was employed to forecast urban floods in Kobe, Japan. The X-MP radar data can be used for flood prediction when coupled with urban flood alert criteria nomographs. Thus, a specific objective of this study was to develop a flood alert criteria nomograph for the Toga River in Kobe, Japan. To evaluate its applicability, flood events were reproduced using the nomograph and the data were compared with observed rain gauge and radar rainfall data of actual flooding events. Additionally, flood occurrences were predicted using the nomograph and forecasted X-MP radar rainfall data using a short-term rainfall prediction method. It was demonstrated that the method is accurate and can provide adequate lead time for flood warnings. (C) 2015 American Society of Civil Engineers.</P>
Seungwon Ha,Hiroki Nagai,Keisuke Asai,Kazuyuki Nakakita,Nobuyuki Tsuboi 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
A blunt body in hypersonic flow is subjected to severe aerodynamic heating and drag. This is one of the most critical problems of designing the hypersonic vehicles such as Reusable Launch Vehicles (RLV). It is well known that spiked-nose (aerospike) concept is effective for aerodynamic drag reduction on asymmetric blunt bodies in hypersonic flow. In this study, we investigated the heat flux distribution on a blunt-nosed body with an aerospike in hypersonic flow. The spike length and the angle of attack were changed to verify the heat reduction effect. The experiment was conducted at Mach l0in the JAXA 0.44-m Hypersonic Wind Tunnel and the temperature of body was measured by using Temperature-Sensitive Paint (TSP), which is a global temperature measurement technique based on photochemical reaction. In addition, the heat flux distribution calculated increase rate or temperature. The flow field around a blunt-nosed body is visualized by schlieren images and compared with TSP images and CFD results to discuss the heat flux distribution. It was found from the result that the heat flux amount is decreased as the length of spike longer and the heat flux distribution is changed widely with the angle of attack. In this study, moreover, the heat-flux and the flow field relation ware clarified by shock/shock interaction analysis of the flow field for different angle-of-attack.
레이더 기반 도시지역 돌발성 호우의 위험성 사전 예측 : 수도권지역 사례 연구
윤성심,나카키타 에이이치,니시와키 류타,사토 히로토,Yoon, Seongsim,Nakakita, Eiichi,Nishiwaki, Ryuta,Sato, Hiroto 한국수자원학회 2016 한국수자원학회논문집 Vol.49 No.9
최근 빈번히 발생하는 도시지역에서의 돌발성 집중호우로 인한 피해를 저감하고자, 기상레이더를 통해 관측되는 자료를 바탕으로 돌발성 호우의 위험성을 사전에 예측하는 기법을 적용하였다. 본 연구에서 활용한 방법은 대기 중의 돌발성 호우를 유발할 수 있는 적란운 대류세포의 조기탐지, 탐지된 대류세포의 자동 추적, 해당 대류세포가 발달하여 돌발성 호우를 유발할 수 있는 가능성을 판단하는 위험예측이라는 3가지 단계를 결합한 것이다. 본 기법은 실제 돌발성 호우로 인해 수도권 지역 소하천에서 시민들이 고립된 사례를 포함한 집중호우 사례에 적용되었다. 그 결과, 레이더 자료만을 이용하여 지상관측망보다 사전에 강우세포를 탐지하고, 국지적 집중호우로 발달하는 현상을 위험도로 판단할 수 있음을 보여 주었다. 본 연구를 통해 제시된 위험도 예측결과를 도시 소하천 홍수대피 업무에 활용한다면 대피시간을 충분히 확보할 수 있어 인명사고를 줄이는 데 기여할 수 있을 것으로 사료된다. The aim of this study is to apply and to evaluate the radar-based risk prediction algorithm for damage reduction by sudden localized heavy rain in urban areas. The algorithm is combined with three processes such as "detection of cumulonimbus convective cells that can cause a sudden downpour", "automatic tracking of the detected convective cells", and "risk prediction by considering the possibility of sudden downpour". This algorithm was applied to rain events that people were marooned in small urban stream. As the results, the convective cells were detected through this algorithm in advance and it showed that it is possible to determine the risk of the phenomenon of developing into local heavy rain. When use this risk predicted results for flood prevention operation, it is able to secure the evacuation time in small streams and be able to reduce the casualties.