• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.57-69
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• 1995

The development of a finite difference model for cross-shore sediment transport prediction in the surf tone due to the storm surge event is presented in this paper. Using the inhomogeneous diffusion equation with moving boundaries. the present numerical model is found to be robust and efficient and does not possess a number of restrictions imposed in Kriebel and Dean's(1985) numerical model. Our numerical model is validated through comparison with the analytical solution. the data of a large-scale experiment and the field data of Hurricane Eloise. The Present model if able to predict the averaged volumetric erosion rate of a beach due to the time-varying real storm surge hydrographs and satisfies the conservation of sediment between eroded volume in the onshore region and deposited volume in the offshore region. In addition. the present model is able to reasonably predict the recession of a beach with wide berm and dune. and can describe the change of a breaking point by the offshore deposition. From the sensitivity analysis or the present numerical model with various input parameters, it is concluded that the present numerical model is able to analyze the beach change in a reliable manner including the effects of different sizes of sediments.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.110-120
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• 2008

Gridded bathymetric data of 30 seconds apart in Korea marginal seas $(30^{\circ}N{\sim}44^{\circ}N,\;117^{\circ}E{\sim}143^{\circ}E)$ are produced. In order to make the data, both updated gridded data of 1 minute apart on internet sites and all the digital nautical charts issued by National Oceanographic Research Institute (NORI) in Oct. 2007 are used. The reference level of the gridded data is approximate level of lowest low water and the horizontal coordinates are based on the WGS84 ellipsoid. Especially a developed computer program can collect all the sounding data including depth contour directly from the digital charts and UTM coordinates of the data are converted to the WGS84 coordinates from which accuracy of data is significantly improved. An interpolation method is adopted to produce the gridded data which are compared and analyzed against the existing gridded data. In this gridded data we can see significantly detailed topographic features which could not be found in the previous data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.621-629
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• 2008

Procedures involved in the refinement of the regional geoid for the area encompassing the Korean peninsula and the East Sea are described, and the computational results are provided. A comparison between the geoid height data, the mean sea surface height and the final product of the refinement work is provided and analyzed. The regional marine geoid thus refined seems to have a better resolution, in terms of its correlation with the bathymetry, and shows the bottom features in a more detailed manner when compared with previously used procedures. The general pattern of the computed geoid profile matches reasonably well with the existing studies, where the correlations between the refined regional marine geoid and the bathymetry are (1) 0.44 for the area $117{\sim}142.5^{\circ}E/24{\sim}52^{\circ}N$ and (2) 0.47 for the area $127{\sim}142.5^{\circ}E/32{\sim}50^{\circ}N$ in the East Sea respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.1-13
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• 2008

In the present work, wave transformation by vertical columns and its wave forces acting on them are discussed using a direct 3-D numerical model based on the VOF (Volume Of Fluid) method. The numerical results for wave transformations and wave forces are critically compared to an advanced experimental data, and provide the verification of the numerical model used in the present study. Overall model-data comparisons are good. After verification of the numerical model, it is used to simulate wave fields around dual vertical columns with arbitrary cross section, and the characteristics of nonlinear wave forces and wave transformations according to the variations of different cross section types of vertical columns, an interval of vertical columns and incident wave angle are discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.692-698
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• 2001

The radio communications by SSB and VHF transceivers are still used very efficiently in coast stations and military base stations. The communication system by the conventional SSB and VHF transceivers between a coast station and a terminal is an one-to-one system. In this dissertation, however, the conventional one-to-one system is expanded to one-to-multiple systems. Then, frequencies can be used effectively for distress, urgency, safety traffic, and military communications. An ICS has been proposed and added, in this dissertation, to the conventional SSB and VHF communication systems, which can realize one-to- several terminal communications. The line switching system by the ICS is to be remote-controlled by ASK modulated PTT signals and audio signals. An ICS can change a connection between terminal and transceiver through a circuit switching system at any time. For this purpose, the author has researched and developed a ASK transmission system, ICS system, control algorithm, multiprocessor system, and moni-toring system. As a conclusion, the developed line switching control systems and equipments can be used effectively for maritime communication, military communication, fishery communication, etc.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.451-451
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• 2015

최근 1900년부터 1990년 사이 해수면은 매년 평균 1.2mm 상승했지만 1990년부터는 매년 평균 3mm씩 높아지고 있으며, 이에 1990년부터 현재까지 해수면 수위의 상승속도가 이전 90년 동안 측정된 수치보다 2.5배 빠르다는 연구결과가 발표되었다. 해수면 상승으로 인한 피해는 범람과 침식을 야기할 수 있으며 해일 및 폭풍으로 인한 피해를 증가시킴으로 물질적 피해와 인명 피해를 유발할 수 있다. 이러한 이유로 해수면 상승에 따른 과학적인 분석과 신뢰성 있는 전망을 통하여 해수면 상승에 따른 대응과 대비가 필요하다. 이에 본 연구에서는 비정상성 빈도해석 방법을 통하여 미래의 해수면 상승을 고려할 수 있는 비정상성 빈도해석 기법을 개발하였다. 본 연구에서는 극치사상을 추출하기 위해 국립해양조사원 (Korea Hydrographic and Oceanographic Administration, KHOA)에서 관리한 45개 조위관측소의 시 조위 자료를 이용하였다. 45개 조위관측소의 한 시간 단위 자료로부터 연최대 및 연평균 조위계열 (annual average and annual maximum sea level series)을 추출하였다. 본 연구에서는 한반도 해안을 동해안, 서해안, 남해안, 제주 권역으로 구분하고 빈도 해석의 신뢰성을 만족하기 위해 자료 구축기간이 20년 이상이며, 각 해안을 나타낼 수 있는 지점을 선정하였다. 비정상성 빈도해석은 Gumbel 극치분포를 적용하였으며, 계층적 Bayesian 기법을 결합하여 매개변수들에 대한 사후분포를 추정하였다. 본 연구에서는 대부분의 지점에서 비정상성 빈도해석 결과와 정상성 빈도해석 결과와 상당한 차이를 보여주고 있으며, 이는 주로 정상성 가정에 기인하는 문제점으로 판단된다. 향후 기후변화에 따른 연안지역의 홍수 및 사회기반시설의 위험도를 평가하기 위해서는 비정상성을 고려한 빈도해석 절차의 수립과 적용이 필요할 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.3
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• pp.146-157
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• 2019

Recently, the importance of highly accurate bathymetric data is greatly emphasized by the increased use of the ocean numerical models and research results in major areas such as ocean forecasting and natural disaster. There are domestic bathymetric data mainly used in ocean numerical models of Choi et al.(2002) and Seo (2008), but the production year is old and the data was created on the basis of nautical charts. Nautical charts are made for the purpose of navigation and based on the minimum depth from bathymetric data, so there is a limitation to reproduce the actual submarine topography. Korea Hydrographic and Oceanographic Agency (KHOA) produces nautical charts every year through continuous bathymetric survey, but no bathymetric data for numerical models have been produced. In this study, using the raw bathymetric survey data, we built an exclusive bathymetric dataset (BADA Ver.1) for ocean numerical models and compared it with published bathymetric data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.1
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• pp.30-37
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• 2021

The Annals of Joseon Dynasity record a significant damage of tsunami in the east coast of Gangwon Province on August 29, 1741. The tsunami occurred near Oshima-Oshima island off the southwestern coast of Hokkaido, Japan, and this study conducted simulations of a ray-tracing model to analyze the effects of the tsunami on the East coast of Korean Peninsula at that time. Model results were calculated using four different depth dataset (ETOPO2m, ETOPO1m, SKKU1m, and GEBCO15c), and results using the highest resolution GEBCO15c showed the best description of the damage recorded in the Annals of the Joseon Dynasty. Based on such, the travel time and paths of the tsunami that reached the main regions of Gangwon Province are presented in detail.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.4
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• pp.68-73
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• 2020

The purpose of this study is to classify species and correct misidentification of cacti (Opuntia) in Jeju area through morphological characteristics comparison. As a result of the study, it was found that Opuntia ficus-indica and O. ficus-indica var. saboten, which has been reported to grow naturally in Jeju Island, is Opuntia stricta. In the morphological comparison of species, it was confirmed that O. stricta showed clear differences in plant size, cladode shape, color of flowers and fruits, and characteristics of areole compared to the existing reported species. Based on the research results, the scientific name of Jeju cactus was corrected as Opuntia stricta, and the Korean name 'Hae-an-sun-in-jang' was newly named. Furthermore, it was suggested that various research literatures and national biodiversity management organizations need to confirm and correct the misidentification of species.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.271-280
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• 2022

Landfast sea ice forms near coastlines in polar regions. Continuous monitoring of this sea ice is important, as it plays a key role in the marine ecosystem and affects the operation of nearby research stations. This study detected landfast sea ice around Jang Bogo research station in East Antarctica by stacking interferometric coherence images of Sentinel-1 synthetic aperture radar (SAR) data with 6-, 12- and 18-day temporal baselines. A total of 50 landfast sea ice maps were generated covering July 2017 to June 2018. The time series revealed regional differences in the timing of the maximum extent as well as growth rate of landfast sea ice. Overall, detecting landfast sea ice using interferometric SAR coherence seems promisingly feasible; however, limitations remain owing to low backscattering coefficients from new and smooth sea ice surfaces and subtle movements of sea ice in contact with the Campbell Glacier Tongue.