• Title/Summary/Keyword: STORM

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A Study on the Effects of the Type of Rainfall Distribution upon the Variation of the Critical Storm Duration : Sanbon Watershed (강우분포형태에 따른 임계지속기간의 변화 연구: 산본유역을 중심으로)

  • Yun, Yeo-Jin;Jeong, Sun-U;Jeon, Byeong-Ho
    • Journal of Korea Water Resources Association
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    • v.31 no.4
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    • pp.375-384
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    • 1998
  • In determining design runoff for the design of drainage systems, the concept of critical storm duration is applied. However, rainfall distribution is usually determined without well-defined standards. In this paper, through the application of ILLUDAS model to Sanbon basin, which is a small urbanized watershed, effects of various rainfall distributing types upon the determination of critical storm duration are throughly analyzed. As a result, it is revealed that peak discharge rates as well as critical storm duration are greatly influenced by the applied of rainfall distributions such as uniform, triangular, trapezoid, huff, central type using IDF curve. Keywords : critical storm duration, rainfall distribution, urban runoff, design storm, ILLUDAS.

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ARE STORM-TIME SUBSTORMS TRIGGERED OR SPONTANEOUS?

  • Lee D.Y.;Kim H.J.;Choi C.R.
    • Journal of Astronomy and Space Sciences
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    • v.21 no.4
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    • pp.295-302
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    • 2004
  • Magnetic storms are almost always accompanied with substorms or substorm-like disturbances. Understanding the nature of the storm-time substorm is important for the currently critical issue of the storm-substorm relation. In this work we have done a statistical analysis in a straightforward way to see whether the storm-time substorms are preferably spontaneous or triggered. On the basis of 301 storm-time substorms selected for this work, we have found that the occurrence of about $28\%$ of them was spontaneous while only $6.5\%$ were associated with a clear trigger(s). The rest of the events were mostly associated with complex variations of IMF. The significant percentage for the spontaneous substorms implies that the possibility of finding a storm without a substorm is greatly reduced due to the spontaneous occurrence of the substorm even when the solar wind and IMF condition remains completely steady during the storm time.

Comparative Study of the Storm Centered Areal Reduction Factors by Storm Types (호우 형태에 따른 호우중심형 면적감소계수 비교)

  • Lee, Dongjoo;Hyun, Sukhoon;Kang, Boosik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.6
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    • pp.1219-1228
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    • 2015
  • The Fixed Area ARFs (Area Reduction Factors) method has limitations in providing exact information about spatial distribution due to the lack of enough density of rain gauge stations. In this study the storm-centered ARF was evaluated between frontal and typhoon storm events utilizing radar precipitation. In estimating storm-centered ARFs, in order to consider the horizontal advection, direction, and spatial distribution of rain cells, the rotational angle of rainfall of each rainfall event and the optimum areal rainfall within the spatial rain cell envelope was taken into account. Compared with the frontal storm, the ARF of typhoon storm shows narrow range of variability. It is noted that the ARFs of frontal storm increases with the rainfall duration, but those of typhoon storm shows opposite pattern. As a result the typhoon ARFs appear greater than frontal ARFs for 1~3 hours of duration, but less for more than 6 hours of duration.

Calculations of Storm Surges, Typhoon Maemi (해일고 산정 수치모의 실험, 태풍 매미)

  • Lee, Jong-Chan;Kwon, Jae-Il;Park, Kwang-Soon;Jun, Ki-Cheon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.20 no.1
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    • pp.93-100
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    • 2008
  • A multi-nesting grid storm surge model, Korea Ocean Research and Development Institute-Storm surge model, was calibrated to simulate storm surges. To check the performance of this storm surge model, a series of numerical experiments were explored including tidal calibration, the influence of the open boundary condition, the grid resolutions, and typhoon paths on the surge heights using the typhoon Maemi, which caused a severe coastal disasters in Sep. 2003. In this study the meteorological input data such as atmospheric pressure and wind fields were calculated using CE wind model. Total 11 tidal gauge station records with 1-minute interval data were compared with the model results and the storm surge heights were successfully simulated. The numerical experiments emphasized the importance of meteorological input and fine-mesh grid systems on the precise storm surge prediction. This storm surge model could be used as an operational storm surge prediction system after more intensive verification.

Analyzing Season and Place of Mars Dust Storm (화성 먼지 폭풍의 공간적 분포와 발생시기 분석 연구)

  • Seo, Haingja;Kim, Eojin;Kim, Joo Hyeon;Lee, Joo Hee
    • Aerospace Engineering and Technology
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    • v.12 no.2
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    • pp.99-107
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    • 2013
  • Local dust storm and lifting to dust frequently occurs in Mars. But it is known to lift dust is associated with atmospheric circulation, the cause of dust lifting is not find yet. The height of dust storm is more than the Himalayas, and the large size dust storm covers half of hemisphere or hemisphere. The kind of dust storm is risk factor to land and to carry out a mission. In this paper, we carry out analysis on the season and place of dust storm, and construct a map with the place of dust storm. We expect that the season and place of dust storm are able to be predicted with being based on the results. And this paper can be utilized as preliminary for selection of landing site and time of launching and landing.

A Study of Storm Surges Characteristics on the Korean Coast Using Tide/Storm Surges Prediction Model and Tidal Elevation Data of Tidal Stations (조석/폭풍해일 예측 모델과 검조소 조위자료를 활용한 한반도 연안 폭풍해일 특성 연구)

  • You, Sung-Hyup;Lee, Woo-Jeong
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.6
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    • pp.361-373
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    • 2010
  • Analysis has been made on the tide/storm surges characteristics near the Korean marginal seas in the 2008 and 2009 years using operational ocean prediction model of the Korea Meteorological Administration(KMA). In order to evaluate its performance, its results were compared with the observed data by tidal stations around Korean Peninsula. The model used in this study predicts very well the characteristics of tide/storm surges near the Korean Peninsula. Simulated storm surges show the evident effects of Typhoons in summer season. The averaged root mean square error(RMSE) of 48 hr forecasting between the modeled and observed storm surges are 0.272 and 0.420 m in 2008 and 2009, respectively. Due to strong sea winds, the highest storm surges heights was found in summer season of 2008, however, in 2009, the high storm surges heights was also found in other seasons. When Typhoon Kalmaegi(2008) and Morokot(2009) approached to Korean Peninsular, the accuracy of model predictions is almost same as annual mean value but the precision accuracy for Typhoon Morakot is lower than of Typhoon Kalmaegi similar to annual results.

Hydraulic Characteristic Analysis of Buoyant Flap Typed Storm Surge Barrier using FLOW-3D model (FLOW-3D 모형을 이용한 부유 플랩형 고조방파제의 수리학적 특성 분석)

  • Ko, Dong Hui;Jeong, Shin Taek;Kim, Jeong Dae
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.26 no.3
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    • pp.140-148
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    • 2014
  • A storm surge barrier is a specific type of floodgate, designed to prevent a storm surge or spring tide from flooding the protected area behind the barrier. A surge barrier is almost always part of a larger flood protection system consisting of floodwalls, dikes, and other constructions. Surge barriers allow water to pass under normal circumstances but, when a (storm) surge is expected, the barrier can be closed. Among the various means of closing, buoyant flap typed storm surge barrier which was indicated by MOSE project in Italy is chosen for Masan bay protection, and the motion of the surge barrier under the action of storm surge and wave is examined using FLOW-3D, a computational fluid dynamics software analyzing various physical flow processes. Numerical result shows that storm surge barrier is successfully operated under wave height 3 m, and tidal range 2 m.

Storm Surge Characteristics According to the Local Peculiarity in Gyeongnam Coast (경남연안의 지역특성에 따른 폭풍해일고의 변동)

  • Hur Dong-Soo;Yeom Gyeong-Seon;Kim Ji-Min;Kim Do-Sam;Bae Ki-Sung
    • Journal of Ocean Engineering and Technology
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    • v.20 no.3
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    • pp.45-53
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    • 2006
  • Each year, the south coast of Korea is badly damaged from storm surge. The damages are greatly dependent upon the local peculiarities of the region where the storm surge occurs. So, in order to prevent/reduce recurrence of the disaster, it is very important to investigate the fluctuation characteristics of the storm surge height, related to the local peculiarities at each coastal area where occurrence of the disaster is expected. In this paper, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the Gyeongnam coast (southeast coast of Korea). Typhoons of Sarah (5914), Thelma (8705) and Maemi (0314), which caused terrible damage to the coastal area in the southeast coast of Korea in the past, were used forstorm surge simulations. Moreover, the storm surge due to virtual typhoons, which were combined the characteristics of each proposed typhoons (Maemi, Sarah, Thelma)with the travel route of other typhoon, was predicted. As expected, the results revealed that the storm surge heights are enhanced at the coastal regions with the concavity like a long-shaped bay. Also, the storm surge heights, due to each typhoon, were compared and discussed at major points along the Gyeongnam coast, related to the local peculiarities, as well as the characteristics and the travel route of typhoon.

Evaluation of Major Storm Events Both Measured by Chukwooki and Recorded in Annals of Chosun Dynasty: 2. Quantitative Approach (조선왕조실록 및 측우기 기록에 나타난 주요호우사상의 평가: 2. 정량적 평가)

  • Kim, Dae-Ha;Yoo, Chul-Sang;Kim, Hyeon-Jun
    • 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.