• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.499-504
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• 2003

This paper describes the system for evaluating the sea wave informations such as wave direction and wave length in real time, by using image data obtained from the marine X-band radar. We proposed here a method for automatic selection of the partial image data without the user's individual selection at the radar. We also discussed that the wave direction could be obtained by a 2-dimensional discrete Fourier transform algorithm. We carried some evaluation works on the algorithm through computer simulation. The obtained thirteen radar image data under several sea surface conditions were analyzed by the method described and the result was presented.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.2
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• pp.75-82
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• 1990

A Wave transformation including wave breaking in shallow water region is a non-linear and discontinuous Phenomenon. Therefore, a so-called individual wave analysis (or a wave by wave analysis) rather than spectral approach seems to be adequate to investigate the wave transformation in such regions. In this study, a theoretical joint distribution of wave height, period and wave direction of zero-down crossing waves, which is required in the individual wave analysis in the shallow water region, is derived based on the hypothesis that sea surface is a Gaussian stochastic process and that a band-width of energy spectra is sufficiently narrow. The derived i oint distribution is found to be an effective measure to investigate characteristics of three-dimensional random wave field in shallow water through field measurements.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.149-157
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• 2008

If we use the microwave of SAR, we can observe ocean in spite of severe weather or night time. The sea surface image of SAR has numerous information about atmospheric phenomena related to surface wind field. The extracted wind information from SAR can be used diversely. In order to extract sea wind speed from SAR image, a generated wind direction from SAR and sigma nought should be input into wind model. Therefore, wind speed can be obtained by input wind direction into CMOD5 Model. Azimuth angle using CMOD5 Model is generated by added $90^{\circ}$ to Look angle which is extracted from SAR data file. A gained wind direction spectrum from SAR image has $180^{\circ}$ ambiguity because of 2D-FFT. This ambiguity should decide to use the location of land, wind direction in field or the result of numerical model. Consequently, wind direction using 2D-FFT is $3^{\circ}{\sim}7^{\circ}$ differences with actual surveying data. Wind speed by CMOD5 model is similar to actual surveying data as below 2m/s.

• Journal of Korea Water Resources Association
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• v.56 no.8
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• pp.521-528
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• 2023

An approach for producing a rip current risk index using the rip current likelihood distribution obtained through the FUNWAVE simulations was applied to a rip current forecast system. The approach originally developed for an observation-based real-time rip current warning system was utilized with wave forecast data instead of observations for the rip current forecast system. The availability of the present approach was checked by comparing the observation-based rip current risk index and the wave forecast-based rip current risk index of the Haeundae Beach in 2021.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.227-230
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• 2007

If we use the microwave of SAR, we can observe on the ocean in spite of bad weather, day and night time. Sea surface images on the ocean of SAR have a lot of information on the atmospheric phenomena related to surface wind vector. Information of wind speed which is extracted from SAR images is used variously. Wind direction data and sigma nought value are put in the CMOD which can extract wind information in order to estimate sea surface wind from SAR images. Wind spectrum which is extracted from SAR always presents opposed two points of $180^{\circ}$ because of applying to 2D-FFT. These ambiguities should be decided by position of land, wind direction or numerical model. Previously, we converted into sigma nought after extracting Digital Number from RadarSat-1 SAR using ENVI4.0, thus, it took a long time because every process was manual. Therefore, we converted sigma nought by matlab code after making matlab code. After that, we are extracting wind direction from sigma nought. Now, to decide wind direction needs further study because wind direction has $180^{\circ}$ ambiguity.

• Journal of Korea Water Resources Association
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• v.55 no.10
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• pp.843-854
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• 2022

For the rip current warning system to reduce rip-current accidents, the implementation method producing the risk index was modified. To produce fast response from the warning system based on real-time observations, the method employed the numerical results (i.e., rip current likelihoods according to the possible scenario) obtained in advance. In this study, instead of using the empirical curve-fitting functions of the previous method, the present modification utilized two-dimensional distributions (i.e., wave height and period, wave height and tidal elevation, wave height and direction, wave height and spreading of frequency-directional spectrum) of rip current likelihoods stacked in a database of the system. The wave and tidal observations in 2021 at the Haeundae coast were applied to the modified system, and its performances at several real events recorded in CCTV images were presented.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.393-395
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• 2012

여수권역 해양교통시설에 해양기상 수집 시스템을 구축하여, AtoN AIS를 이용하여 주변을 항해중인 선박에 해양기상 정보를 직접 제공하고, AIS 기지국을 통해 해양기상 정보를 수집 처리하여 연안여객터미널, 해경 파출장소, 유관기관을 해양기상 정보를 제공함으로서 도서민이나 해양에 종사하는 사람, 레져 인구에게 제공하는 서비스로서 해양교통시설을 활용하여 좀 더 안전한 해양 업무를 수행하고 사고로 인한 인명 및 물적, 환경적인 피해를 줄일 수 있도록 한다. 여수권역 해양교통시설에 6개 국소와 별도의 기상관측 부이를 설치하여 대기기상(풍향/풍속, 기온/습도, 기압, 시정) 과 해양기상(유향/유속, 파향/파고, 수온)을 관측 할 수 있도록 구축하였으며, 기상관측 표준화법에 맞게 센서를 검정하고, 설치하여 관측 자료의 신뢰성을 확보하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.555-556
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• 2010

연안 수역에서의 해상교통 환경변화에 부응하고 나아가 대형 해양사고 방지와 인명사고 예방을 위해 필요한 해양기상신호표지 시스템 구축을 위하여 해양기상 관측 및 항로표지 정보제공 시스템을 도입, 통항선박에게 안전항해에 필요한 정보를 제공함으로서 해양교통 안전을 확보하고자 한다. 인천 연안의 팔미도를 포함한 15개 항로표지시설에 기상(온습도, 풍향/풍속, 기압) 및 해양(유향/유속, 수온, 파고/파향) 관측시스템을 설치하고 항로표지용 AIS (AtoN AIS) 통신시스템을 이용하여 육상 정보수집 처리서버 및 항행 선박에게 해양기상관측자료를 실시간 전송하는 시스템을 구축하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.175-177
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• 2018

항해용 X-band 레이더는 물표탐지를 통한 안전한 항해를 목적으로 널리 사용되고 있다. 해당 목적을 위해서는 노이즈로 간주되는 해면반사파(sea clutter)신호는 제거하여 사용하지만, 본 연구에서는 노이즈로 간주되는 해면반사파 신호를 활용하여 파랑에 대한 정보(파고, 파주기, 파향 등)를 파악하는데 활용하였다. 레이더에서 방출되는 전자기파는 펄스의 길이에 의해 탐지할 수 있는 영역이 제한되어 있다. 펄스의 길이가 짧을수록 짧은 주기의 파랑을 계측할 수 있다는 장점이 있지만, 거리의 제약으로 인하여 대형선박의 실 운항시에는 활용하기 어려운 현실적인 딜레마가 있다. 본 연구에서는 삼성중공업, 오션알앤디가 개발한 WaveFinder 시스템을 이용하여 기존 short pulse 모드 뿐만아니라 midium pulse 에서의 활용 가능성을 실제 시운전을 통해 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1191-1201
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• 2014

The rip current warning index function, which estimates the likelihood of dangerous rip current in the real-time rip current warning system operating to help mitigate against rip current accidents at Haeundae beach, was studied. The rip current warning index evaluated as a function of various real-time observations was developed based on Choi et al. (2013b). This study shows a version of rip current warning index improved by including the effect of wave direction and spreadings of frequency-directional spectrum on rip current likelihood. The wave and tidal observations in 2012 at Haeundae coast were applied to the rip current index function, and its performances at several real events found based on CCTV images were presented and analyzed.