• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.121-126
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• 2006

Modern Ocean wave forecasting systems predict the mean sea state, as characterized by the wave spectrum, in a box of size ${\Delta}x{\Delta}y$ surrounding a grid point at location x. It is shown that this approach also allows the determination of deviations from the mean sea state, i.e. the probability distribution function of the surface elevation. Hence, ocean wave forecasting may provide valuable information on extreme sea states.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.113-120
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• 2006

In this paper, generation mechanisms of ocean freak waves are briefly introduced in the context of wave-current interaction phenomena. As an accurate and efficient numerical tool, the spectral element method is presented with general features and specific treatment for the wave-current interaction problem. The present model of the fluid motion is based on the Navier-Stokes equations incorporating a velocity-pressure formulation. In order to deal with the free surface motion, an Arbitrary Lagrangian-Eulerian (ALE) description is adopted. As an intermediate stage of development, solution procedure and characteristic aspects of the present modeling and numerical method features are addressed in detail, and numerical results for wave-current interaction is left as further study.

• 한국해양공학회지
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• 제30권1호
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• pp.1-9
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• 2016

In order to convert wave energy into large quantities of high-efficiency power, it is necessary to study the optimal converter system appropriate for the environment of a specific open ocean area. A wave energy converter system with a counterweight converts the translation energy induced from the heave motion of a buoy into rotary energy. This experimental study evaluated the primary energy conversion efficiency of the system, which was installed on an ocean generating basin with a power take-off system. Moreover, this study analyzed the energy conversion performance according to the weight condition of the buoy, counter-weight, and flywheel by changing the load torque and wave period. Therefore, these results could be useful as basic data such as for the optimal design of a wave energy converter with a counterweight and improved energy conversion efficiency.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제3권1호
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• pp.23-28
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• 2000

A numerical investigation was made to examine characteristics of rectangular pontoon type floating breakwaters in oblique waves. Sway and heave wave exciting forces, roll moment acting on the floating breakwater and three motion reponses decrease as the incident wave angle increases for the most of the wave ranges. There exists a minimum wave transmission coefficient which is a function of wave frequency. In short wave range wave transmission coefficient increases as the incident wave angle increases. In long wave range, however, wave transmission coefficient decreases as the wave incident angle increases.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제1권)
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• pp.175-180
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• 2006

본 연구는 제주도 서측 해역의 현지 파랑관측 자료를 기초로 해양파의 비선형 특성을 조사한 것으로서, 실제 해역에서의 Freak wave 예보의 토대를 마련하기 위한 기초 연구이다. 관측된 파랑자료의 비선형 특성을 조사하기 위해 파형의 상하 비대칭성, 전후비대칭성, 빈도 분포의 첨예도, 파랑 스펙트럼의 대역폭 파라미터 등을 추출하고 이를 자료를 유의파고, 최대파고 등의 파랑 특성치들과의 상관관계를 분석하였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.263-267
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• 2004

This paper presents a comparative study on numerical and wave-maker generated waves. The wave-makers employed to carry out the experiments have mathematical forms. The linear and quadratic models were tested. When it comes numerical analysis, the authors used the FLUENT which is widely used commercial code. Only two dimensional cases were considered. The experiments were done in a small wave flume. The waves were generated for various frequencies to examine the characteristics of the water waves. The comparison of the numerical and wave-maker generated waves were made.

• International Journal of Fluid Machinery and Systems
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• 제9권3호
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• pp.222-228
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• 2016

Almost 70% of the earth is covered by the ocean. Extracting the power available in the ocean using a wave energy converter has been seen to be eco-friendly and renewable. This study focuses on developing a method for analyzing a wave energy device that uses a cross-flow turbine. The motion of the ocean wave causes an internal bi-directional flow of water and the cross-flow turbine is able to rotate in one direction. This device is considered of double-hull structure, and because of this structure, sea water does not come into contact with theturbine. Due to this, the problem of befouling on the turbine is avoided. This study shows specific relationship for wave length and several motions.

• 한국해양공학회지
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• 제17권5호
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• pp.25-31
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• 2003

Numerical experiments have been conducted using the nonlinear combined refraction-diffraction model, in order to analyze the generation characteristics of stem wave, which is formed by the interaction between vertical structure and the oblique incident waves. The results of stem wave are discussed through the stem wave height distribution along/normal vertical structure, under the wide range of incident wave conditions-wave heights, periods, depths, and angles. Under the same wave height and period, the larger the incident wave angle, the higher the stem wave heights. According to the results of wave height distribution, in front of vertical structure, the maximum of stern wave heights occurs in the location bordering the vertical wall. Furthermore, the most significant result is that stem waves occur under the incident angles between $0^{\circ}\;and\;30^{\circ}$, and the stem wave height ratio has the maximum value, which is approximately 1.85 times the incident wave height when the incident wave angle becomes $23^{\circ}$.

• 한국해양공학회지
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• 제28권1호
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• pp.6-11
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• 2014

This paper presents the results of an experimental study of wave run-ups on a semi-submersible offshore structure. A series of model tests with a 1:80 scale ratio were carried out in the two-dimensional wave basin of MOERI/KIOST. The experimental model had two columns and one pontoon. The model was fixed and wave elevations were measured at five points per column. Two different draft (operational & survival) conditions and three wave heights were considered under regular wave conditions. First, the nonlinear characteristics of wave run-ups are discussed by using the time series data. Then, the wave heights are compared with numerical results based on the potential flow model. The comparison shows fairly good correlation between the experiments and computations. Finally, wave run-ups under the operational and survival conditions are suggested.

• 대한조선학회논문집
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• 제58권6호
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• pp.339-347
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• 2021

Piston type wave makers or flap type wave makers are usually adopted as a wave maker which disturbing the fluid domain with sinusoidal motion. Recently hybrid wave maker which could be operated as not only piston type and/or flap type but also swing type wave maker have been devised by utilizing the link mechanism. The wave board of hybrid wave maker has been devised to be independently controlled by the horizontal actuators on upper and lower end of the wave board. The wave board could operate as a flap type wave board when the lower hinge is in a stationary condition and the upper hinge is operated with sinusoidal motion. On the contrary, the swing type wave board could be obtained by the lower hinge is activated and the upper hinge is in a stationary condition. When both end of the wave board is activated in a synchronized condition, the wave board motion become piston motion. In addition the hybrid wave maker could enhance the piston motion with flap motion or swing motion by selecting control parameters. Various wave board motion of hybrid wave maker and relevant wave form have measured on the wave board and departed location. It is appeared that the novel hybrid wave maker could be utilized for the improvement of wave qualities in experiments.