• Journal of the Korean earth science society
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• v.23 no.3
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• pp.259-269
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• 2002

Based on sedimentary structures, degree of bioturbation, and internal erosional layers, the deep-sea core sediments in the East Sea (Ulleung and Yamato basins) and the Northwestern Pacific Ocean (Shikoku Basin) can be divided into two parts (upper and lower) with the boundary of around 10,000 years B.P. in age. The upper part of core KT94-10 from Shikoku Basin is characterized by low sedimentation rate, internal erosion layer, high degree of bioturbation and cross-lamination structures. It can be interpreted as the bottom-current deposits which show some different characteristics from turbidite or hemipelagic sediment. However, its lower part consists of highly bioturbated, massive mud, suggesting that it be not related to the influence of bottom current. On the other hand, the cores in Ulleung and Yamato basins do not show any evidence of bottom-current deposits: their upper parts consist of bioturbated mud, and lower parts are characterized by laminated mud with pyrite filaments, indicating anaerobic condition. Consequently, these sedimentological characteristics suggest that deep-sea circulation would be changed from slow-moving to fast-moving one at this bounding time commonly in the Northwestern Pacific Ocean and the East Sea. Also, even in the same time, the deep-sea circulation in the Northwestern Pacific area would be relatively faster than that in the East Sea.

• Journal of the Mineralogical Society of Korea
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• v.26 no.2
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• pp.65-80
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• 2013

Sediment transport mechanism and distribution of organic sediments are elucidated by the study of particle size, mineralogy, organic matters and microfossils of the surface samples collected from seafloor adjacent Dokdo island. Shallow marine sediments are dominated by coarse- grained sediments including gravel and sand, and their sedimentation has mainly been controlled by traction. While the samples collected from oceanic zone are characterized by high contents of fine- grained sediments such as silt and mud in bulk sediments, and the changes of mineral compositions including clay minerals and feldspar, and the fine sediments have been deposited mainly by suspension. The change of organic sedimentary communities is detected between neritic and oceanic zone. Although marine organic matter is predominant in neritic zone, terrestrial organic matter is monopolized according to increasing water depth. This trend is associated with grain size of sediments. The results also suggest that high pollen concentrations in whole organic matters may played an important role in excessive organic carbon in sediment.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.57-60
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• 1995

연안에서 파랑은 심해에서는 해수면 근방에서 운동량이 크며 따라서 구조물에 작용하는 힘도 해수면 근방에서 크다. 반면 천해역에서는 해저면에서의 운동량도 상당하며, 이러한 해저면에서의 파랑에 관련된 수입자의 운동은 해저 퇴적물의 이동에 직접 영향을 미친다. 해저면에서의 비활 조건(no-slip condition)에 의하여 파랑 경계층내의 해수의 거동은 복잡하다. 이러한 해저면 경계층의 거동을 파악하기 의한 접근 방법은 크게 둘로 나눌 수 있다. (중략)

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.50-62
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• 1999

Sediment core samples recovered from the Korea Deep Ocean Study (KODOS)-97 area were divided into two or three units according to their distinct changes in sediment colors and chemical and physical properties. Analyses of radiolarian faunas in the sediments and $^{10}Be$ ratios in each unit were performed to reveal stratigraphic and paleoceanographic history of the study area. In the upper part of the sediments, Tertiary radiolarians were mixed at various proportions with Quaternary assemblages probably by reworking process of bottom current and benthic animals. Dissolution of radiolarians was severe in deeper depth and in the Unit III, only few of the fragments of corroded Tertiary radiolarians were detectable. The mid layer of the Unit I belonged to Collosphaera invaginata Zone, the time period of 0.21 Ma. The Unit II belonged to Collosphaera tuberosa Zone with the time period younger than 0.42 Ma which was observed above the Stylatractus universus Zone. The Unit III is assigned to Tertiary, which is younger than the Late Eocene. Composition analyses of radiolarian assemblage and $^{10}Be$ ratio data indicated hiatus periods of more than 3 My between late of Middle Miocene and Pliocene resulting from erosion and dissolution caused by Antarctic Bottom Water. Stratigraphic evidence from radiolaria was well correlated with $^{10}Be$ data. Sedimentation rate during Quaternary can be suggested as 0.15-0.5 mm per 1000 years. Dominance of warm-water radiolaria species and the results reflected minimum climatic changes of tropical conditions.

• 한국해양학회지
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• v.29 no.1
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• pp.17-27
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• 1994

The sediment collected from KODOS91-1 were studied using X-ray diffraction(SRD) analysis to clarify the composition and vertical distribution of clay minerals. Micropaleontological data(Radiolarians) was applied to identify the changes in post-depositional environment and chemical mechanism leading to the formation of authigenic minerals. The result show that the highest concentration of smectite is occurred in the lower part(Unit II, III) of sediment column and the lowest concentration in the upper part(Unit I) whereas terrestrial minerals, such as illite, kaolinite and quartz, indicate the opposite trends. Radiolarians in the upper part are composed entirely of Quaternary/Tertiary mixtures, whereas in lower sediment units generally revealed the middle Miocene to the Eocene. This may imply that the Quaternary and Tertiary sedimentary processes were continuously affected by reworking of older sediments and subsequent resegmentation. The changes of the sediment color, peak pattern of minerals and presence of reworked microfossils at the unit boundaries have been interpreted as evidence of authigenic formation. Mineralogical characteristics of the sediments in study area strongly indicates changes in paleoenvironments through geologic time, including changes in post-depositional conditions by physical processes and chemical mechanisms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.281-287
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• 2009

In this study, the behavior of breasting dolphin caused by the maximum wave height in the coastal area of Incheon has been investigated. The dynamic deflection, shear stress and moment of pile are analyzed using the coefficient of horizontal subgrade reaction resulted from loading tests for different DWT (Dead Weight Tonnage). The dynamic characteristics of pile in accumulated and dredged soils show almost the same pattern. It is shown that the resistance of dolphin to external load increases as the diameter of pile increases. The bettered pile dolphin is more than 10 times stable than the vertical pile type based on the study of dynamic characteristics of dolphin.

• 한국해양학회지
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• v.30 no.4
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• pp.288-301
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• 1995

Rates of the sedimentation and particle mixing have been estimated by applying uranium-series disequilibrium techniques to three sediment cores collected from the korea Deep Ocean Study (KODOS) site between the clarion and Clipperton Fracture Zones (CCFZ) of the Equatorial Pacific. Sedimentation rates based on the profiles of excess /SUP 230/Th activity and /SUP 230/ Th/SUB xs//SUP 232/ Th activity ratios at the southeastern part of the study area were estimated to be in the order of a few millimeters per thousand year, while at the northwestern part a factor of ten lower. Excess activities of /SUP 230/Th and /SUP 230/Th ratios showed intervals of constant values in the upper part of the sediment cores, probably generated by biological particle mixing. A "two-box" advection-diffusion steady state mixing model was employed in order to estimate particle mixing rates in the upper and the lower layers, based on the distribution profiles of excess /SUP 210/Pb activities. Particle mixing coefficients were estimated to be in the order of 10$^1$ cm$^2$/y in the upper layer and 10/SUP -1/-10/SUP 0/ cm$^2$/y in the lower layer.

• Geophysics and Geophysical Exploration
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• v.20 no.3
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• pp.146-162
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• 2017

Multibeam and seismic data in the northwestern part of the Ulleung Basin were analyzed to study stratigraphy and evolutionary history of submarine canyon. A detailed analysis reveals that the sedimentary sequences in this area consist of four stratigraphic units separated by erosional unconformities. On the continental slope, these units are dominated by well-stratified facies with some slope failures, whereas these units show well-stratified and chaotic facies toward the basin floor. Generally, the sediment thickness is relatively thin on the slope, whereas thick sediment accumulation occurs on the base of slope and basin floor. Based on seismic characteristics and distribution, the deposition of each units are well correlated with the evolutionary history of the submarine canyon. Unit 1 directly overlying the acoustic basement has thin sediment layer on the slope, whereas its thickness gradually increase toward the basin floor. Compared to other units, Unit 2 is relatively thick accumulations on the slope and contains some slope failures related to faults systems. The mass transport sediments due to slope failures, mainly deposited on the base of slope as a submarine fan. The width and depth of submarine canyon increase due to dominant of the erosional process rather than the sediment deposition. Unit 3 is thin accumulation on the slope around the submarine canyon. Toward the basin floor, its thickness gradually increases. Unit 4 is characterized by thin layers including slides and slumps on the slope, whereas it formed thick accumulations at the base of slope as a submarine fan. The increase in the width and depth of submarine canyon results from the dominant of the erosional process and slope failures around the submarine canyon. Consequently, the formation of sedimentary units combined with the development of submarine canyon in this area is largely controlled by the amounts of sediment supply originated from slope failures, regional tectonic effects and sea-level fluctuations.

• 한국해양학회지
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• v.26 no.1
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• pp.59-66
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• 1991

Laboratory studies were carried out to measure the sound velocity (V/SUB p/) and quality factor (Q/SUB p/, inverse attenuation) in the horizontal (H) and vertical (V) direction on the core sampled sediment of deep-sea basin (1,850 meter water depth), East Sea of Korea (Sea of Japan). Sampled core was about 250 cm long and 500 kHz ultrasonic p-wave transducer was used for a sound soured. V/SUB p/ varies from 1,480 m/sec to 1,500 m/sec, it is not clear which direction is faster, V/SUB PH/ or V/SUB pv/, within${\pm}$ 1.0% anisotropy (A/SUB p/). It is thought because the core sediment facies is highly (or slightly) bioturbated homogeneous mud with very high porosity (more than 80%). The general trend of Q/SUB p/ is decreasing 10 to 5 with the buried depth, it is strongly affected by the variation of sediment texture (increasing silt, decreasing clay) with increasing of CaCO$_3$ and organic matter content, But Q/SUB PH/ is jumping up to 14.9 near the bottom of core sediment as including volcanic ash richly. The relationship between V/SUB PH/ and Q/SUB PH/ shows the mirror image nearly, it is interpreted that not only the geotechnical properties and texture but also sea-water characteristics (high Q/SUB p/, low V/SUB p/) according to rich water content affect strongly in the upper part of the unconsolidated deep-sea basin sediment.

• The Korean Journal of Malacology
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• v.10 no.2
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• pp.10-23
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• 1994

패류화석은 지구를 이루는 퇴적암 중 석회암을 이루고 있는 주요 구성원 중의 하나이다. 지난 20년간 지질학자 및 해양학자들은 주로 심해에 쌓여 있는 퇴적물 중의 미화석(microfossil)을 이용하여 과거의 기후 및 해양의조건을 규명하기 위하여 많은 노력을 하여왔다. 그 결과로서 지질학적 시대 중 중생대 이후로부터 신생대에 이르기까지 지구 전반에 영향을 주었던 고기후에 대한 많은 정보가 얻어졌다. 또한 일부 학자들에 의하여 천해에 서식하였던 여러 화석들의 생태와 지화학적 분석(geochemical analysis)을 통하여 지엽적인 고기후(paleoclimate) 및 고해양학적(paleoceanographic)이해도 증진되어 온 것이 사실이다. 천해에 서식하고 있는 석회질 골격(calcareous skeleton)을 만드는 생물종들은 주로 생화확적인 작용을 통하여 아라고나이트와 방해석이라는 탄산염 광물을 침전시킨다. 특히 이 중에서 아라고나이트라는 광물은 불안정하여 속성작용 (퇴적물이 쌓인 후 거치는 물리, 화학적 작용)동안에 방해석으로 변하게 된다. 따라서 특이한 속성환경의 조건에 의해 아라고나이트로 보존되어 있는 패류를 제외하고는 주로 방해석으로 이루어진 화석의 분석을 통하여 고환경 복원을 위한 여러 정보를 얻을 수 있다. 이를 근거로 하여 분석 대상이 주로 된 것은 완족류나 방해석으로 이루어진 이매패류(e.g., 굴등)이었다.우리나라에서는 최근에 이르러서야 패류 화석의 지화학적 분석을 통하여 고해양학적 연구가 수행되기 시작하였다. 신생대 제 3기 마이오세에 해당하는 포항 부근에서 발견되는 연체동물 화석들은 변질이 안된 상태로서 우리에게 매우 귀중한 고해양학적 정보를 제공한다. 과거에 생물이 자랐던 성장 온도는 산소 동위원소의 비를 측정하여 구할 수 있는데 그결과에 의하면 해수의 온도가 현재보다 약간 높았음을 지시한다. 제주도 내의 서귀포 부근에서는 현재 천연기념물로 지정되어 있는 서귀포층내에서 많은 화석들이 산출되고 있다. 이 시대는 빙하기와 간빙기가 교호하던 시대로서, 분석 결과에 의하면 서귀포층이 쌓일 당시에 우리 나라는 빙하기의 영향을 받았던 것으로 생각된다.