• Ocean Systems Engineering
• /
• v.13 no.1
• /
• pp.1-20
• /
• 2023

An iterative focused wave generation method is developed and implemented in a local analytic based Navier-Stokes solver. This wave generation method is designed to reproduce the target focused wave by matching the target amplitude spectrum and phase angle. A 4-waves decomposition scheme is utilized to obtain the linearised component of the output wave. A model test studying the interaction between different focused waves and a fixed cylinder is selected as the target for the wave generation approach. The numerical wave elevations and dynamic pressure on the cylinder are compared with the experimental measurement and other state-of-the-art numerical methods' results. The overall results prove that the iterative adjustment method is able to optimize the focused wave generated by a CFD approach.

• Journal of information and communication convergence engineering
• /
• v.5 no.3
• /
• pp.223-228
• /
• 2007

This paper deals with the secondary excited induction generator applied to random wave input generation system. As it is preferred to stabilize the output voltage and frequency in the constant level, microcomputer controlled CSI connected to the secondary windings supplies the secondary current with slip frequency. For testing this method, the input torque simulator is constructed, according to the power flow analysis. The experimental and numerical results show the advantage of secondary excited induction generator system for the random input wave generation system.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.29 no.4
• /
• pp.169-179
• /
• 2017

In this study, we applied the wave generation method by relaxation method to the SWASH model, which is a non - hydrostatic numerical model, for stable and accurate wave generation of linear and nonlinear waves. To validate the relaxation wave generation method, we were simulated various wave, including the linear wave and nonliner wave and compared with analytical solution. As a result, the incident wave was successfully generated and propagated in all cases from Stokes waves to cnoidal wave. Also, we were confirmed that the wave height and the waveform were in good agreement with the analytical solution.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.6
• /
• pp.861-866
• /
• 2011

This paper described the hybrid power generation using ocean wave that consists of linear power generation system and vibrational power generation system. The linear power generation system is made up of the winding coil, the permanent magnet and it is performed stable generation regardless of the wave frequency using directly the ocean wave velocity. And the vibration power generation system consists of the winding coil, the permanent magnet and spring. When the vibration system natural frequency in the vibrational power generation system is tuned to the ocean wave frequency, the relative velocity of between the winding coil and the permanent magnet is faster than the velocity of ocean wave up and down motion, then we can obtain more the electric power. Therefore, in this paper, the proposed hybrid power generation using ocean wave have merits that obtaining the more electric energy in resonance frequency and carrying out stable generation even over the range of resonance frequency.

• Journal of Ocean Engineering and Technology
• /
• v.27 no.6
• /
• pp.32-42
• /
• 2013

In this paper, a wave-induced swirl water chamber (SWC) for breakwater and wave power generation is introduced and its applicability to wave power generation in the coastal waters of Korea is investigated. The SWC type of wave power generation is a way to drive a turbine using the unidirectional swirl flow that is induced in the back of a curtain wall of a breakwater due to incident waves. The typical wave characteristics are obtained by analyzing the annual statistical wave data from KHOA (Korea Hydrographic and Oceanographic Administration). A numerical analysis is carried out on the variations in the SWC entrance height, wave height, and different installation conditions. For the numerical analysis, a commercial code, Fluent based on FVM, is used. As the entrance height decreases, the mass flow rate through the entrance is rarely changed, whereas the magnitude of the flow velocity of the smaller entrance height is greater than the other ones, which is better for the formation of an SWC swirl flow inside and the flow kinetic energy at the entrance. In cases of installation conditions where a wall is place behind and under SWC, it has been shown that the mass flow rate through the entrance is greater than that in the open condition, and sufficient flow kinetic energy is generated in the entrance for wave power generation. However, the swirl flow kinetic energy is relatively small. Thus, in the future, it is necessary to study the swirl flow generation, which is affected by the SWC shape.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.8
• /
• pp.1028-1034
• /
• 2011

This paper have been studied that ocean wave power vibration generation system with two D.O.F.(degree of freedom) consists of buoy and vibration generation system with two D.O.F. for using efficiency of ocean wave energy. It selected main frequencies ${\omega}_1$, ${\omega}_2$ in frequency with ocean wave and it fitted them to the natural frequencies of vibration system with two D.O.F. in the vibrational power generation system. Then each the relative velocity of between the winding coil and the permanent magnet is faster than the velocity of ocean wave up and down motion by resonance phenomenon. Also the ocean wave power generation with two D.O.F. obtained the more electric energy then the ocean wave power generation with one D.O.F. by coupling effect for two D.O.F. vibration system. Therefore ocean wave power vibration generation system with two degree of freedom that is proposed in this paper has merits which not only using more energy in the ocean wave but also obtaining more electronic energy.

• Journal of Ocean Engineering and Technology
• /
• v.18 no.6 s.61
• /
• pp.8-15
• /
• 2004

Wave power distribution is investigated to determine the optimal sites for wave power generation at Jeju sea which has the highest wave energy density in the Korean coastal waters. The spatial and seasonal variation of wave power per unit length is calculated in the Jeju sea area based on the monthly mean wave data from 1979 to 2002 which is produced by the SWAN wave model simulation in prior research. The selected favorable locations for wave power generation are compared in terms of magnitude of wave energy density and distribution characteristics of wave parameters. The results suggest that Chagui-Do is the most optimal site for wave power generation in the Jeju sea. The seasonal distribution of wave energy density reveals that the highest wave energy density occurs in the northwest sea in the winter and it is dominated by wind waves, while the second highest one happens at south sea in the summer and it is dominated by a swell sea. The annual average of wave energy density shows that it gradually increases from east to west of the Jeju sea. At Chagui-Do, the energy density of the sea swell sea is relatively uniform while the energy density of the wind waves is variable and strong in the winter.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.6
• /
• pp.23-28
• /
• 2011

In this paper, a new generation method for ship induced waves is proposed using the fully non-linear 3-D numerical model with non-reflected wave generation system (LES-WASS-3D). A ship induced wave generated by the newly proposed method is examined in comparison with that obtained by an empirical formula. It is then shown that there is a good agreement in free surface the elevation between them. As a result, it is revealed that a ship induced wave in a 3-D numerical wave field can be simulated well using LES-WASS-3D.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.3B
• /
• pp.305-308
• /
• 2011

In this study, generation methods of 3-D multi-directional random wave are examined using the fully non-linear numerical model with non-reflected wave generation system (LES-WASS-3D). Directional distribution functions obtained by EMLM method are compared for multidirectional random waves generated by various generation methods. As a results, it is revealed that multi-directional wave field can be simulated using LES-WASS-3D.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.1
• /
• pp.166-174
• /
• 2009

Gijang Sea is located on the southeastern coast of Korea. This study establishes a basic system to identify optimal sites for the wave power generation. To achieve this goal, the field measurements were made at the field site in front of Dong-am fishing port at Gijang. In addition, we analyzed the offshore wave data at the Donghae buoy operated by Korea Meteorological Administration(KMA) and compared the data with the wave characteristics in Gijang Sea. The main results were as follows. In winter, the wave direction in Gijang Sea ranged between east and south($90{\sim}180^{\circ}$). The main wave direction was east($90^{\circ}$). The Significant wave heights and periods were under 2 m and $5{\sim}15$ sec, respectively. A comparison of water depth and wave direction constitutes one(condition) of the important parameters for selecting the optimal site for the wave power generation.