• Economic and Environmental Geology
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• v.54 no.6
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• pp.717-731
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• 2021

We analyzed the characteristics of the habitat environment for the Seonam study area in Ulsan, the southern shore of the East Sea using bathymetry and seafloor environment data. The depth of the study area ranges from about 0 m to 23 m. In the west of the study area, the water depth is shallow with a gentle slope, and the water depth becomes deeper with a steep slope in the east. Due to the right-lateral strike-slip faults located in the continental margin of the East Sea, the fracture surfaces of the seabed rocks are mainly in the N-S direction, which is similar to the direction of the strike faults. Three seafloor types (conglomeratic-grained sandy, coasre-graiend sandy, fine-grained sandy) and rocky bottom area have been classified according to the analyses of the bathymerty, seafloor image, and surface sediment data. The rocky bottom areas are mainly distributed around Seaoam and in the northern and southern coastal area. But the intermediate zone between Seonam and coastal area has no rocky bottom. This intermediate area is expected to have active sedimentation as seawater way. The sandy sediments are widely distributed throughout the study area. Underwater images and UAV images show that Cnidarians, Brachiopods, Mollusks are mostly dominant in the shallow habitat and various Nacellidae, Mytilidae live on the intertidal zone around Seonam. Annelida and Arthropod are dominant in the sandy sediments. The distribution of marine organism in the study area might be greatly influenced by the seafloor type, the composition and particle size distribution of the seafloor sediments. The analysis of habitat environment mapping with bathymetry, seafloor data and underwater images is supposed to contribute to the study of the structure and function of marine ecosystem.

• Journal of the Korean association of regional geographers
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• v.9 no.2
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• pp.203-216
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• 2003

The process of constructing coastal digital elevation model(DEM), for the 3 dimensional analysis, is composed by abstracting land layers for land elevation and water depth, reprojecting UTM, relocating geographical grid, and interpolating works. The geomorphic set of shallow sea, including tidal current, tidal zone deposition, and water depth distribution, was analyzed by eye search of Landsat TM image, masking of land zone, band combination and regression analysis. Some horizontal differences, between combined DEM and surveyed data of shallow sea, was corrected for analysis. Analyzed geomorphic elements are stream channel, alluvial fan, coastal terrace, tidal current. and shallow sea bank. Results of analysis present that transported fluvial materials influence tidal sedimentation, especially from Gahwacheon river, for the role of artificial draining flooding waters from Jinyang Reservoir, almost in the summer season. In the coastal area with less tidal current, more fine materials are deposited. The influence of currental deposition are higher on small pockets with west coast of well developed terraces. The lower skirt of alluvial fans developed into the tidal zone of shallow sea. Small pocket type bays are closed by coastal current, and less influenced from tidal deposition. The bank of Jinju Bay are developed originally from submerging of remnant erosional mountain ranges, and play on the role of trapping fine materials.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.1
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• pp.1-9
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• 2020

ABL (Airborne Bathymetric LiDAR) is an advanced survey technology that uses green lasers to simultaneously measure the water depths and oceanic topography in coastal and river areas. Seabed point cloud extraction is an essential prerequisite to further utilizing the ABL data for various geographic data processing and applications. Conventional seabed detection approaches often use return waveforms. However, their limited accessibility often limits the broad use of the bathymetric LiDAR (Light Detection And Ranging) data. Further, it is often questioned if the waveform-based seabed extraction is reliable enough to extract seabed. Therefore, there is a high demand to extract seabed from the point cloud using other sources of information, such as geometric information. This study aimed to assess the feasibility of a ground filtering method to seabed extraction from geo-referenced point cloud data by using CSF (Cloth Simulation Filtering) method. We conducted a preliminary experiment with the RIGEL VQ 880 bathymetric data, and the results show that the CSF algorithm can be effectively applied to the seabed point segmentation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.436-445
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• 2007

An analytical solution which can be applied to an arbitrarily varying topography is derived by using the continuity and momentum equations. Applying the fact that the solution of the governing equation is expressed as Bessel function in such case that the water depth varies linearly, the present solution is obtained by assuming the water depth as series of constant slope. The present solution is verified by comparing with analytical solution derived previously and investigates the effects of bottom topography to run-up height of vertical structure.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.52-52
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• 2010

동해 한국대지 남부(south Korea Plateau)에서 2010년 2월에 한국해양연구원의 온누리호를 이용하여 해저지형 및 자생광물 탐사가 실시되었다. 다중빔 음향측심기를 이용한 해저지형 조사는 2-3 km 탐사측선 간격으로 약 400 L-km 정도가 실시되었다. 조사구역 A($37^{\circ}$ 16'-18'N, $130^{\circ}$ 02'-16'E)는 890-1,900 m의 수심범위와 남쪽으로 갈수록 수심이 깊어져 울릉분지(Ulleung Basin)와 연결된다. 크고 작은 소규모의 구릉이 사면을 따라 다수 분포하고 있다. 조사구역 B($37^{\circ}$ 26'-40'N, $130^{\circ}$ 23'-34'E)의 정상부는 900-1,000 m로 비교적 평평하게 나타났고, 남동방향으로는 2,200 m까지 급격하게 수심이 증가하는 사면으로 이루어져 있다. 한국대지내 노출 암반지역은 남동쪽 사면의 일부 지역에 분포하고 있다. 자생광물 탐사는 일차적으로 천부지층 탄성파탐사를 수행하여 시료채취 가능 여부를 현장에서 확인한 후에, A 및 B구역내 11개 지점에서 드렛지를 이용하여 암석시료를 채취하였다. 채취된 암석은 주로 현무암이며, 많은 양의 화산기원 부석(pumice) 및 화산재(box core 자료)도 확인되었다. 또한, 인광석으로 추정되는 암석과, 망간단괴(manganese nodules)와 망간각(manganese crust)의 일부 시료도 채취하는데 성과가 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.328-328
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• 2017

해운대 해변은 한국에서 가장 유명한 해변 중 하나로 국제적으로도 널리 알려져 매년 많은 관광객을 끌어들이는 부산의 대표 관광지 중 하나이다. 그러나 근래 들어 해운대에서 이안류가 자주 발생하며 관광객들이 불안해하고 있다. 해운대 해변에서 해수욕을 즐기던 관광객들이 이안류에 휩쓸려 구조된 사례가 2013년에만 500명을 넘는 것으로 보고되고 있다. 다행히 아직까지 이 지역에서 이안류로 인한 인명사고는 보고되지 않았으나 매년 발생하는 이안류에 대한 공포로 사회적인 경각심이 고조되고 있는 실정이다. 이에 따라 해운대 이안류의 발생 메커니즘을 규명하고자 하는 연구가 꾸준히 진행되고 있으며, 이안류 사고에 대비한 경보체계 구축 등의 연구도 병행되고 있다. 해운대 이안류의 발생원인을 공학적으로 규명할 수 있다면 향후 해운대 해변의 방재대책 수립을 위한 핵심자료로 사용될 수 있으며, 타 지역에서 발생하는 이안류의 원인분석 및 대책수립을 위한 참고자료로서도 중요한 역할을 할 수 있다. 본 연구에서는 최근 국내외에서 발표된 해운대 이안류 발생원인에 대한 고찰을 기초로 해저지형으로 인한 해운대 이안류 거동의 변화를 수치모델을 활용하여 분석하였다. 널리 알려진 Boussinesq 방정식 모델인 FUNWAVE-TVD를 사용하였으며, 병렬 연산을 활용하여 수치모의 시간을 단축하였다. 해운대 이안류는 해저지형의 변화에 따라 이안류 발달 장소가 달라지긴 하였으나 전체적인 양상은 크게 변하지 않는 것으로 나타났다.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.477-486
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• 2017

In this study, we analyze precise seabed geomorphology and conditions for comparing the nearshore areas of the Dongdo(East Island) and the Seodo(West Island) using detailed bathymetry data and seafloor backscattering images, in Dokdo, the East Sea. We have been obtained the detailed bathymetry data and the seafloor backscattering data. The survey range is about $250m{\times}250m$ including land of islets to the nearshore areas of the southern part of the Dongdo and the Seodo. As a result of bathymetry survey, the southern area of the Dongdo(~50 m) is deeper than the Seodo(~30 m) in the water depth. The survey areas are consist of extended bedrocks from land of the Dongdo and the Seodo. The underwater rock region of the Seodo is larger than the Dongdo. In spite of similar extended rocks features from islets, there are some distinctive seabed characteristics between the southern nearshore areas of the Dongdo and the Seodo. The Talus-shaped seafloor environment formed by gravel and underwater rocks originating from the land of the Dongdo is up to about 15 m depth. And the boundary line of between extended bedrocks and seabottom is unclear in the southern nearshore of the Dongdo. On the other hand, the southern coast of the Seodo is characterized by relatively large scale underwater rocks and evenly distributed sediments, which clearly distinguish the boundary of between extended bedrocks and seafloor. This is because the tuff layers exposed to the coastal cliffs of the Dongdo are weak against weathering and erosion. It is considered that there are more influences of the clastic sediments carried from the land of the Dongdo compared with the Seodo. Particularly, the land of the Dongdo has been undergoing construction activities. And also a highly unstable ground such as faults, joints and cracks appears in the Dongdo. In previous study, there are dissimilar features of the massive tuff breccia formations of the Dongdo and the Seodo. These conditions are thought to have influenced the different seabed characteristics in the southern nearshore areas of the Dongdo and the Seodo.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.186-194
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• 2000

bottom as a reference basis, some theoretical elements which form bottom echoes during acoustic survey of demersal fish were considered. A stable bottom detection method based on maximum voltage difference, which was not influenced by variable levels and waveform transformation. The method has been shown to be effective using in-situ bottom echo waveforms and computer simulation data. A comparison between near-bottom SV profiles acquired in Funka Bay, Hokkaido, of Japan, the East China Sea and the Yellow Sea, of Korea, with the threshold method and maximum differential voltage method, shows that the SV obtained with the maximum differential voltage method is 4-6 dB higher than those with threshold method within 2m from the bottom.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.172-175
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• 1996

외해로부터 해안선부근으로 이동하는 파랑은 해저협곡 및 대륙붕과 같은 해저지형의 변화, 방파제와 같은 해안구조물과의 상호간섭 및 파랑상호간의 비선형효과 등에 의해 굴절, 회절, 천수 및 쇄파 등과 같은 변화를 경험한다. 파랑변형의 원인이 되는 여러 변화 중에서 흥미 있고 연구할 가치가 있는 물리적 현상중의 하나는 Bragg 반사이다. (중략)

• The Science & Technology
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• v.32 no.10 s.365
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• pp.78-80
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• 1999

20세기 중반인 세계2차대전중에 수집된 미국ㆍ독일ㆍ영국해군의 해양관측자료들은 대서양 등 3대 해양의 현상과 신비를 파악하는데 크게 기여했다. 미국을 비롯한 선진 해양국가들은 대형 탐사선으로 해저지형과 해저층세 또는 판구조원리를 연구하여 20세기 후반의 해양학은 깊은 바다 해수의 물리적 특성과 생물순환의 비밀까지 규명할 수 있게 되었다.