• 한국해양공학회지
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• 제21권2호
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• pp.35-41
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• 2007

In general, coastal damage is mostly occurred by the action of complex factors, like severe water waves. If the maximum storm surge height combines with high tide, severe water waves will overflow coastal structures. Consequently, it can be the cause of lost lives and severe property damage. In this study, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the coast in front of Noksan industrial complex, Korea. Moreover, the shallow water wave is estimated by applying wind field, design water level considering storm surge height for typhoon Maemi to SWAN model. Under the condition of shallow water wave, obtained by the SWAN model, the wave overtopping rate for the dike in front of Noksan industrial complex is calculated a hydraulic model test. Finally, based on the calculated wave-overtopping rate, the inundation regime for Noksan industrial complex was predicted. And, numerically predicted inundation regimes and depths are compared with results in a field survey, and the results agree fairly well. Therefore, the inundation modelthis study is a useful tool for predicting inundation regime, due to the coastal flood of severe water wave.

• 한국해양공학회지
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• 제19권2호
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• pp.12-18
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• 2005

Typhoon Maemi landed on the southeast coast of Korea and caused a severe storm surge in Jinhae Bay and Masan Bay. The tide gage in Masan Port recorded the storm surge of a maximum of more than 2m and the area of more than 700m from the Seo Hang Wharf was flooded by the storm surge. They had not met such an extremely severe storm surge since the opening of the port. Then storm surge was hindcasted with a numerical model. The typhoon pressure was approximated by Myers' empirical model and super gradient wind around the typhoon eye wall was considered in the wind estimation. The land topography surrounding Jinhae Bay and Masan Bay is so complex that the computed wind field was modified with the 3D-MASCON model. The motion of seawater due to the atmospheric forces was simulated using a one-layer model based on non-linear long wave approximation. The Janssen's wave age dependent drag coefficient on the sea surface was calculated in the wave prediction model WAM cycle 4 and the coefficient was inputted to the storm surge model. The result shows that the storm surge hindcasted by the numerical model was in good agreement with the observed one.

• 한국해양공학회지
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• 제5권1호
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• pp.16-24
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• 1991

This paper presents a method of the reliability analysis for a tension leg platform(TLP)in severe storm waves by using the first passage concept of the random tensile stress in the tendons. In the present method, two failure conditions are considered ;i.e., the exceedance of the ultimate tensile capacity and the occurrence of the negative tension. In order to consider the correlation effects between the failure events for each corner resulted from the rupture of all tencons at one corner, a new system limit state for a rectangular shaped TLP is developed, which is defined in terms of the TLP motions in the vertical plane ;i.e., heave, roll, and pitch. To illustrate the validity of the present method, the numerical analysis is carried out for two TLP's with different structural dimensions. Then, the results are compared with those by other methods.

• 대기
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• 제21권3호
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• pp.243-256
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• 2011

This paper presents the development of new algorithm for identifying and tracking the convective cells in three dimensional reflectivity fields in Cartesian coordinates. First, the radar volume data in spherical coordinate system has been converted into Cartesian coordinate system by the bilinear interpolation. The three-dimensional convective cell has then been identified as a group of spatially consecutive grid points using reflectivity and volume thresholds. The tracking algorithm utilizes a fuzzy logic with four membership functions and their weights. The four fuzzy parameters of speed, area change ratio, reflectivity change ratio, and axis transformation ratio have been newly defined. In order to make their membership functions, the normalized frequency distributions are calculated using the pairs of manually matched cells in the consecutive radar reflectivity fields. The algorithms have been verified for two convective events in summer season. Results show that the algorithms have properly identified storm cells and tracked the same cells successively. The developed algorithms may provide useful short-term forecasting or nowcasting capability of convective storm cells and provide the statistical characteristics of severe weather.

• 한국물환경학회지
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• 제33권2호
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• pp.160-169
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• 2017

The objective of this study are to analyze changes in future rainfall patterns in the Soyang-dam watershed according to the RCP 4.5 scenario of climate change. Second objective is to project peak flow and hourly sediment simulated for the future extreme rainfall events using the SWAT model. For these, accuracy of SWAT hourly simulation for the large scale watershed was evaluated in advance. The results of model calibration showed that simulated peak flow matched observation well with acceptable average relative error. The results of future rainfall pattern changes analysis indicated that extreme storm events will become more severe and frequent as climate change progresses. Especially, possibility of occurrence of large scale extreme storm events will be greater on the periods of 2030-2040 and 2050-2060. In addition, as shown in the SWAT hourly simulation for the future extreme storm events, more severe flood and turbid water can happen in the future compared with the most devastating storm event which occurred by the typhoon Ewiniar in 2006 year. Thus, countermeasures against future extreme storm event and turbid water are needed to cope with climate change.

• 대기
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• 제18권2호
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• pp.147-158
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• 2008

Domestic IOP (intensive observing period) has mostly been represented by the KEOP (Korea Enhanced Observing Period), which started the 5-yr second phase in 2006 after the first phase (2001-2005). During the first phase, the KEOP had focused on special observations (e.g., frontal systems, typhoons, etc.) around the Haenam supersite, while extended observations have been attempted from the second phase, e.g., mountain and downstream meteorology in 2006 and heavy rainfall in the mid-central region and marine meteorology in 2007. So far the KEOP has collected some useful data for severe weather systems in Korea, which are very important in understanding the development mechanisms of disastrous weather systems moving into or developing in Korea. In the future, intensive observations should be made for all characteristic weather systems in Korea including the easterly in the central-eastern coastal areas, the orographically-developed systems around mountains, the heavy snowfall in the western coastal areas, the upstream/downstream effect around major mountain ranges, and the heavy rainfall in the mid-central region. Enhancing observations over the seas around the Korean Peninsula is utmost important to improve forecast accuracy on the weather systems moving into Korea through the seas. Observations of sand dust storm in the domestic and the source regions are also essential. Such various IOPs should serve as important components of international field campaign such as THORPEX (THe Observing system Research and Predictability EXperiment) through active international collaborations.

• 한국해양공학회지
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• 제22권3호
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• pp.8-17
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• 2008

Wrenching climatic changes due to ecocide and global wanning are producing a natural disaster. Coastal zones have been damaged by typhoons and accompanying storm surges. Severe waves, and destruction of the environment are adding to the severity of coastal disasters. There has been an increased interest in these coastal zone problems, and associated social confusion, after the loss of life and terrible property damage caused by typhoon Maemi. Especially if storm surges coincide with high ticks, the loss of life and property damage due to high waters are even worse. Therefore, it is desirable to accurately forecast not only the timing of storm surges but also the amount water level increase. Such forecasts are very important from the view point of coastal defense. In this study, using a numerical model, storm surge was simulated to examine its fluctuation characteristics for the coastal area behind Masan Bay, Korea. In the numerical model, a moving boundary condition was incorporated to explain wave run-up. Numerically predicted inundation regimes and depths were compared with measurements from a field survey. Comparisons of the numerical results and measured data show a very good correlation. The numerical model adapted in this study is expected to be a useful tool for analysis of storm surges, and for predicting inundation regimes due to coastal flooding by severe water waves.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2018년도 정기학술대회 발표논문집
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• pp.66-66
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• 2018

• 한국통신학회논문지
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• 제39B권3호
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• pp.188-190
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• 2014

MANET(Mobile Ad-hoc Networks)에서 참여 노드 수가 증가할수록 경로탐색을 위해 브로드캐스팅되는 제어메시지가 폭발적으로 증가하게 되어 네트워크 성능을 감소시킨다. 본 논문에서는 이런 브로드캐스트 스톰 문제(broadcast storm problem)의 발생 확률을 낮춰 네트워크 성능을 높일 수 있는 노드 상태 제어 알고리즘을 제안한다.

• 한국해안·해양공학회논문집
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• 제20권1호
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• pp.93-100
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• 2008

Multi-nesting grid system을 이용한 한국해양연구원의 해일모델을 해일고 산출에 사용하기 위해 검증하였다. 다양한 수치실험은 2003년 9월 내습한 태풍 매미를 기준으로 이루어졌다. 이 태풍해일모델의 성능을 알아보기 위해 조석검증을 비롯하여 개방경계조건, 격자 크기 그리고 태풍의 진로 등에 대한 일련의 수치실험이 실시되었다. 본 연구에서 기상입격자료인 해면기압장과 바람장은 CE wind 모델로 계산하였다. 총 11개 조위관측소의 1분 간격 조위자료와 모델 결과를 비교하였으며, 해일고를 성공적으로 재현하였다. 이러한 실험들은 정밀한 해일고 산출에 있어 기상자료의 중요성과 상세정밀격자의 필요성을 강조하기 위한 것이다. 이 태풍해일 모델은 보다 세밀한 검증과정을 거친다면 해일고 예측을 위해 상시 운용될 수 있다고 사료된다.