• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.29-42
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• 1992

자유표면하에 잠긴 복잡한 3차원 물체 주위의 흐름을 해소하기 위한 수치계산법이 TUMMAC(Tokyo Univ. Modified Marker And Cell)법을 기초로 하여 개발되었다. 임의물체의 no-slip 3차원 물체표면조건을 보다 간단히 처리하기 위하여 "porosity"라는 개념이 도입되었으며, 담수성에 잠겨 있는 해저돌출물 주위의 유동을 계산하여 그 응용성을 검토하였다. 돌출물 후방의 복잡한 와동들의 상호간섭이 잘 시뮬레이션 되었다.시뮬레이션 되었다.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.128-132
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• 2010

울릉분지 북동쪽 독도 주변 해역은 해수면 위의 작은 섬들과 해저에 큰 화산체로 구성된 독도와 해수면 아래 큰 규모의 해산 두 개(심흥택해산, 이사부해산)가 위치하고 있으며 그 중 해수면위로는 독도만 솟아 있다. 정밀해저면영상기(MS-1000)를 이용하여 큰 규모의 조사선으로 접근이 어려웠던 동도-서도 주변 연안에 대한 정밀해저면영상 조사를 2010년 1월에 소형조사선을 이용하여 수행하였다. 부두 동쪽 해안은 동도와 근접하고 있어 큰 규모의 돌출 암반이 많이 분포하고 있으며 부두 북쪽으로는 모래층의 연흔구조가 많이 나타나며 소규모의 암반 및 자갈들이 많이 분포하는 것으로 판단된다. 동도와 서도사이의 해저면영상을 분석해보면 동도 선착장부근으로는 모래퇴적물의 연흔구조가 많이 나타나고 동도와 서도 중앙부로 가면서 모래보다는 작은 자갈들이 많이 분포하며 서도쪽으로 가면서는 모래 및 자갈퇴적물이 암반구조로 이루어져있는 것으로 판단된다. 정밀해저면영상기(MS-1000)는 고정밀한 해저면영상을 획득할 수 있으며 불규칙한 지형으로 기존 장비가 접근하없어지며기 어려운 해저지형에도 사용하기 적합한 것으로 판단된다. 향후 항구 및 해안구조물 등과 같은 고정밀해저면영상이 필요한 분야에 활용성이 높을 것으로 생각되고 또한 유지/보수가 필요한 수중 군시설 및 부두시설에 대한 정밀조사를 통하여 효율적 관리 정보제공할 수 있을 것으로 판단된다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.187-198
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• 2003

High-resolution (Chirp, 3-11 kHz) echo facies and sedimentary facies of piston-core sediments were analyzed to reveal the late Quaternary depositional processes in the Korea Plateau and Ulleung Interplain Gap. The Korea Plateau is an Isolated topographic high with a very restricted input of terrigenous sediments, and its slope is characterized by a thin sediment cover and various-scale submarine canyons and valleys. Echo and sedimentary facies suggest that the plateau has been moulded mainly by persistent (hemi) pelagic sedimentation and intermittent settling of volcanic ashes. Sediments on the plateau slope and steep margins of ridges and seamounts were reworked by earthquake-induced, large-scale slope failures accompanied by slides, slumps and debris flows. As major fraction of the reworked sediments consists of (hemi) pelagic clay particles, large amounts of sediments released from mass flows were easily suspended to form turbid nepheloid layers rather than bottom-hugging turbidity currents, which flowed further downslope through the submarine canyons and spreaded over the Ulleung Basin plain. In the Ulleung Interplain Gap, sediments were introduced mainly by (hemi) pelagic settling and subordinate episodic mass flows (turbidity currents and debris flows) along the submarine channels from the slopes of the Oki Bank and Dok Island. The sediments in the Ulleung Interplain Channel and its margin were actively eroded and reworked by the deep water flow from the Japan Basin.

• 한국해양학회지
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• v.7 no.2
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• pp.74-85
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• 1972

This paper studied the grain size distribution of bottom sediments of Yeongil Bay which is located at the southeastern part of the Korean Peninsula. Sixty four samples collected with snapper and dredger are analyzed by roe Tap Sieve Shaker and Pipette Method. The moment parameters are calculated with the method of Friedman(1961). Most samples are composed of sand size sediments and a few samples are composed of silt and clay. The Yeongil Bay can be divided into gravel-granule zone, sand zone, and silt-clay zone. The sediments near Yeonam- Dong and Hyongsan river are moderately sorted and others are very poorly sorted according to scheme of Friedman91962). In general, sorting values are ranged from 1.0 to 3.5. The samples near Janggigap and Masin-Dong show negative and others show positive skewness values. Skewness values are ranged from -1 to 2. All samples show the leptokurtic distribution except for the samples near Masin- dong and at the deepest place near Janggigap. Kurtosis values are ranged from -1.5 to 21.9. The samples of gravel-granule zone contain more than 50% and those of silt-clay zone contain less than 50% of CaCO$\_$3/. Four different colors, black, yellow, brown and gray, are shown in the sediments of Yeongil Bay.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.589-601
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• 2023

We compare high-resolution seabed bathymetry data and seafloor backscattering data acquired, using multi-beam, between 2018 and 2021 to understand topographic changes in the coastal area of Dokdo. The study area, conducted within a 500 m × 500 m in the southern coast between the islands where Dongdo Port is located, has been greatly affected by human activities, waves and ocean currents. The depth variations exhibit between 5 - 70 m. Irregular underwater rocks are distributed in areas with a depth of 20 m or less and 30 - 40 m. As a whole, water depth ranges similar in the east-west direction and become flatter and deeper. The bathymetry contour in 2020 tends to move south as a whole compared to 2018 and 2019. The south moving of the contours in the survey area indicates that the water depth is shallower than before. Since the area where the change in the depth occurred is mainly formed of sedimentary layers, the change in the coast of Dokdo were mainly caused by the inflow of sediments, due to the influence of wind and waves caused by these typhoons (Maysak and Haishen) in 2020. In the Talus area, which developed on the shallow coast between Dongdo and Seodo, the bathymetry changed in 2020 due to erosion or sedimentation, compared to the bathymetry in 2019 and 2018. It is inferred that the changes in the seabed environment occur as the coastal area is directly affected by the typhoons. Due to the influence of the typhoons with strong southerly winds, there was a large amount of sediment inflow, and the overall tendency of the changes was to be deposited. The contours in 2021 appears to have shifted mainly northward, compared to 2020, meaning the area has eroded more than 2020. In 2020, sediments were mainly moved northward and deposited on the coast of Dokdo by the successive typhoons. On the contrary, the coast of Dokdo was eroded as these sediments moved south again in 2021. Dokdo has been largely affected by the north wind in winter, so sediments mainly move southward. But it is understood that sediments move northward when affected by strong typhoons. Such continuous coastal change monitoring and analysis results will be used as important data for longterm conservation policies in relation to topographical changes in Dokdo.

• Journal of the Korean Geographical Society
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• v.43 no.6
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• pp.791-807
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• 2008

The purpose of this study is to analyze landform characteristics and geomorphic processes in Dokdo seamount. For geomorphic analysis, bathymetry data were collected by multi-beam echosounder and the seismic survey was also conducted. Through the detailed analysis of depth, slope, aspect and erosional landform, Dokdo Seamount is characterized by a flat or gently sloping top of $2^{\circ}$ or less and seamount slope with $14{\sim}40^{\circ}$ gradient. There are protrusion of landform around the Dokdo on top of the Dokdo seamount. It is inferred that the features are formed by collapsed debris deposits or remained bedrocks by differential erosion in the past. The massmovement topography including slump and slide is shown on seamount slope with $14{\sim}40^{\circ}$ gradient. In addition, gullies with various length are developed on the Dokdo seamount slope. Slope erosional processes occur more actively along the submarine gullies on the Dokdo seamount. It is inferred that the massmovement processes on the slope of Dokdo seamount are related to earthquake activities and evolution of submarine volcano. Consequently, slope of the Dokdo seamount has retreated by erosional processes of mass-movement and submarine gullies.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.729-742
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• 2020

In this study, we analyze seabottom conditions and characteristics integrated with topographic data, seafloor mosaic, underwater images and orthophoto(drone) of soft-hard bottom area around the Sib-Ri rock in the northern shore of the East Sea(Gyeongpo Beach, Gangneung). We obtained field survey data around the Sib-Ri rock(about 600 m × 600 m). The Sib-Ri rock is formed by two exposed rocks and surrounding reef. The artificial reef zone made by about 200 ~ 300 structures is shown the western area of the Sib-Ri rock. The underwater rock region is extended from the southwestern area of the exposed the Sib-Ri rock with 9 ~ 11 m depth range. The most broad rocky seabottom area is located in the southwestren area of the Sib-Ri rock with 10 ~ 13 m depth range. The study area were classified into 4 types of seabottom environment based on the analysis of bathymetric data, seafloor mosaics, composition of sediments and images(underwater and drone). The underwater rock zones(Type I) are the most distributed area around the Sib-Ri Rock(about 600 m × 600 m). The soft seabottom area made by sediments layer showed 2 types(Type II: gS(gravelly Sand), Type III: S(Sand)) in the areas between underwater rock zones and western part of the Sib-Ri rock(toward Gyeongpo Beach). The artificial reef zone with a lot of structures is located in the western part of the Sib-Ri rock. Marine algae(about 6 species), Phylum porifera(about 2 species), Phylum echinodermata(about 3 species), Phylum mollusca(about 3 species) and Phylum chordata(about 2 species) are dominant faunal group of underwater image analysis area(about 10 m × 10 m) in the northwestern part of the Sib-Ri rock. The habitat of Phylym mollusca(Lottia dorsuosa, Septifer virgatus) and Phylum arthropoda(Pollicipes mitella, Chthamalus challengeri hoek) appears in the intertidal zone of the Sib-Ri rock. And it is possible to estimate the range and distribution of the habitat based on the integrated study of orthphoto(drone) and bathymetry data. The integrated visualization and mapping techniques using seafloor mosaic images, sediments analysis, underwater images, orthophoto(drone) and topographic data can provide and contribute to figure out the seabottom conditions and characteristics in the shore of the East Sea.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.219-228
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• 2011

In this paper, the design procedure of substructure of the steel-type breakwater was described and the actual foundation design was performed for the test bed. The site investigation was executed at the Osan-port area, in Uljin, Gyeongbuk, where the steeltype detached breakwater is constructed. The foundation mainly depends on the lateral load and uplift force due to the wave force. Since the superstructure is stuck out about 9.0m from the ocean bed, the foundation must resist on the lateral force and bending moment. After considering various factors, the foundation type of this structure was determined by the steel pipe pile(${\varphi}711{\times}t12mm$). On the stability of pile foundation, the safety factors of the pile on the compressive, lateral and uplift forces were grater than the minimum factor of safety. The displacements of pile under the working load were evaluated as the values below the permissible ones. Based on the subgrade reaction method, we evaluated the relationship of subgrade reaction and displacement for the lateral and the vertical directions in the layers. The structural analyses along with the foundation were perfomed and the effect of pile foundations were compared quantitatively.