• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.33-44
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• 2000

Ships in a seaway will encounter dangerous situation, such as slamming, stranding, and capsizing. The number of capsizing is small, but the loss due to them is very large from the viewpoint of human life, property, and the environmental pollution. The number of capsizing of fishing vessels is about 62% of total number of capsizing, and the half of them is originated from the operational mistake in a seaway. So the dynamics and the capsizing phenomena are to be studied, and the guide for the safe operation of a fishing vessel in a seaway are to be specified. The hydrodynamic forces consist of radiation forces (which are due to the motion of a ship), Froude-Krylov forces (which is due to the incoming waves), and diffraction forces (which is due to the wave and ship interaction). These forces are calculated by well-known strip method. Using the calculated forces, the motion of a ship in a regular sea is obtained. In the real seaway, the waves are very irregular, therefore the statistical analysis is very helpful. In this paper, using the results of the motion in a regular seaway and the wave spectrum, the motion in a irregular seaway are obtained and analyzed.

• The Journal of the Korea Contents Association
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• v.7 no.4
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• pp.170-177
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• 2007

When buoyant objects appear in contents, it is helpful in developing contents to express their attributes such as their length, width, weight, and velocity, and the magnitude and direction of regular waves dynamically. Therefore, we verify how the attributes of buoyant objects and the characteristics of waves cause the heaving motion of buoyant objects to change by using the equation of motion used in the naval architecture and ocean engineering. Our research results may help contents developers to develop contents with buoyant objects even if they do not understand the naval architecture and ocean engineering well. We show that we can calculate the motion of buoyant objects dynamically even if the velocity of buoyant objects or the characteristics of waves change dynamically. In the future, we will study how buoyant objects move on the irregular waves, and develop engines for buoyant objects on the real sea.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.287-289
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• 2001

많은 자연계가 선형성과 비선형성을 동시에 포함한 카오스적인 모습을 보여준다 예를 들면 춤추는 불꽃, 부서지는 파도. 하늘에 떠다니는 무수한 구름 등 외관상으로는 불규칙해 보이는 듯 하면서 어떤 규칙성을 가진 다양한 모습을 나타낸다. 특히 공학분야에서는 거의 모든 현상이 비선형계로 이루어져 있다 이러한 비선형계의 해석에 카오스 이론이 적용될 수 있는데 최근 들어 카오스에 내재하는 질서구조가 밝혀짐에 따라 여러 공학분야에서 이를 활발히 응용하고 있다. 본 논문에서는 카오스 이론에 대해 간단히 논하고 이러한 카오스 이론이 응용될 수 있는 분야를 공학적 측면에서 일목요연하게 정리하였다. 특히 전력계통 및 송배전설비 분야 중 GIS 상태감시 및 부분방전 검출기법에 대해서 시계열 데이터를 이용한 카오스 이론의 적용 가능성을 타진하였다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.3
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• pp.132-145
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• 2016

In case of the seabed around and under gravity structures such as submerged breakwater is exposed to a large wave action long period, the excess pore pressure will be generated significantly due to pore volume change associated with rearrangement soil grains. This effect will lead a seabed liquefaction around and under structures as a result from decrease in the effective stress. Under the seabed liquefaction occurred and developed, the possibility of structure failure will be increased eventually. In this study, to evaluate the liquefaction potential on the seabed quantitatively, numerical analysis was conducted using the expanded 2-dimensional numerical wave tank model and the finite element elasto-plastic model. Under the condition of the regular wave field, the time and spatial series of the deformation of submerged breakwater, the pore water pressure (oscillatory and residual components) and pore water pressure ratio in the seabed were estimated.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.2
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• pp.49-63
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• 1989

Wave drift forces which are small in magnitudes compared to the first order wave exciting forces can cause very large motion of a vessel in waves. In this paper a theoretical and experimental analysis is made of the mean and slowly varying wave dirft forces on the semi-submersible platform. Theoretical calculations are performed by using near field method with three dimensional diffraction theory and model tests are carried out in regular and irregular waves with a 1/60 semi model. Test results are compared with theoretical calculations and the mooring spring effects in the test are discussed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.103-113
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• 2001

This study presents Quaternary sedimentation pattern around Dok-Island volcanoes (Dok Island and Dok Seamount), based on analysis of high-resolution (chirp) echo characters. Echo facies If, showing sharp, continuous bottom echo without subbottom reflectors, is recorded mainly from the flat tops of the volcanoes. This facies indicates sands and gravels (re) deposited by shallow marine processes. Echo facies IIA in the basin floor and basal slopes of the volcanoes and Oki Bank is characterized by semi-prolonged bottom and several parallel subbottom echoes. This facies reflects hemipelagic settling with intermittent influences of turbidity currents in the slope areas. Echo facies IIC is recorded from acoustically-transparent debrite masses on the basal slopes of the volcanoes and Oki Bank. Echo facies IIIA is characterized by irregular hyperbolic echoes in the slope areas of the volcanoes. It suggests hard rock basement or irregular volcanic edifices. Echo facies IIIC shows regularly-overlapping hyperbolic bottom echoes. It is interpreted to represent rock-fall deposits (talus) accumulated in the mid-slope area. Echo characters and topography suggest that the tops of Dok-Island volcanoes were flattened and lowered by shallow-marine erosional processes. The eroded sediments were transported to and deposited in the base of slope and basin plain mainly by debris flows and turbidity currents along submarine canyons and valleys.