• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.2
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• pp.95-106
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• 1999

A numerical model is represented to calculate the wave fields such as the reflected waves, the transmitted waves and the depth-averaged velocities over submerged breakwaters for the normally incident wave trains of nonlinear mono-chromatic wave and solitary wave. The finite amplitude shallow water equations with the effects of bottom friction are solved numerically in time domain using an explicit dissipative Lax-Wendroff finite difference method. The numerical model is verified by comparisons with the other numerical results and the measured data. It is found that the submerged breakwater may be more useful for protecting the energies of monochromatic waves rather than solitary waves. Finally, the armor stability on submerged breakwater is indirectly analyzed using the hydrodynamic characteristics of flow fields.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.51-58
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• 2003

The magnitude of evanescent modes in terms of dynamics it investigated in case that the transformation of water waves is predicted by the linear wave theory. For the waves propagating over two steps, the eigenfunction expansion method is used to predict the amplitudes of reflected and transmitted waves by the component of evanescent modes as well as propagating modes. Then. the relative importance of evanescent modes to the propagating modes is investigated. The numerical experiments find that the evanescent modes are pronounced at the relative water depth of k$_1$h$_1$＝0.11$\pi$ and the water depth ratio of h$_2$/h$_1$ close to zero.

• Proceedings of the Korea Water Resources Association Conference
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• 1999.05a
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• pp.469-475
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• 1999

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.109-117
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• 2022

There has been an increasing number of studies on photovoltaic energy generation system in an offshore site with the largest energy generation efficiency, as increasing the researches and developments of renewable energies for use of offshore space and resources to replace existing fossil fuels and resolve environmental challenges. For installation and operation of floating photovoltaic systems in an offshore site with harsher environmental conditions, a stiffness of structural members comprising the total system must be reinforced to inland water spaces as dams, reservoirs etc., which have relatively weak condition. However, there are various limitations for the reinforcement of structural stiffness of the system, including producible size, total mass of the system, economic efficiency, etc. Thus, in this study, a floating breakwater is considered for reducing wave loads on the system and minimizing the reinforcement of the structural members. Wave reduction performances of floating breakwaters are evaluated, considering size and distance to the system. The wave loads on the system are evaluated using the higher-order boundary element method (HOBEM), considering the multi-body effect of buoys. Stresses on structural members are assessed by coupled analyses using the finite element method (FEM), considering the wave loads and hydrodynamic characteristics. As the maximum stresses on each of the cases are reviewed and compared, the effect of floating breakwater for floating photovoltaic system is checked, and it is confirmed that the size of breakwater has a significant effect on structural responses of the system.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.727-727
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• 2012

최근 제체 설치수심의 대수심화로 인해 직립 케이슨제의 건설이 주를 이루고 있으며, 외곽시설의 경우 평면배치에 의하여 곡면부 구간이 형성된다. 이와 같은 구간에서는 파랑 증폭이 발생할 수 있다. 특히 우각부 구간에서의 파랑증폭에 의한 월파량 산정은 기존 직각으로 입사하는 조건에 대한 월파량 산정 방법과는 다른 해석이 필요하다. 본 연구에서는 직립제 우각부에 대한 월파량 분포를 검토 및 분석하고자 한다. 그림 1과 같이 우각부의 각도를 $10^{\circ}{\sim}30^{\circ}$로 제작했으며, 각각 발생시킨 파랑의 주기는 1.18초, 1.38초, 1.57초, 1.77초, 1.98초, 파고는 7.5cm, 10cm, 12.5cm이다. 또한 그림 2와 같이 각 월파가 일어나는 직립제 모형의 여유고를 7.5cm, 10cm, 12.5cm, 15cm를 적용하였다. 우각부 구간에서 월파의 공간적인 분포를 수리모형 실험을 통하여 검토하였다. 월파의 공간적인 분포를 검토하기 위하여 월파량 영향계수( )를 도입하였다. 우각부가 없는 직각으로 입사하는 조건의 월파량 실험을 통해 그 월파량의 값이 영향계수의 $r_x=1.0$이며, 우각부 중심을 기준으로 구조물을 따라서 공간적인 월파량 영향계수를 산정하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2329-2341
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• 2013

In this study, we develop an algorithm to predict swell-like significant waves in the east coast of Korea using the directional wave gauge which is installed near Sokcho. Using the numerical wave model SWAN, we estimate wave data in open sea from the wave data observed through the directional wave gauge. Then, using the wave ray method with the open-sea wave data as offshore boundary conditions, we predict the swell-like significant waves at several points in the east coast of Korea. We verify the prediction methods with the SWAN and wave ray methods by comparing numerically predicted data against either target or measured data at the observation site. We can improve the prediction of the swell-like significant waves in the east sea of Korea using both the real-time wave measurement system and the present prediction algorithm.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.3
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• pp.149-159
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• 2014

In this study, we develop an algorithm to predict swell-like high waves on the east coast of Korea using the directional wave gauge which was installed near Sokcho. Using the numerical wave model SWAN, we estimate wave data in open sea from the wave data collected by using the directional wave gauge. Then, using the wave ray method and SWAN model with the open-sea wave data as offshore boundary conditions, we predict the swell-like high waves at several major points on the east coast of Korea. We verify the prediction methods with the SWAN and wave ray methods by comparing predicted data against measured one at Wangdolcho. We can improve the prediction of the swell-like high waves in the east sea of Korea using both the real-time wave measurement system and the present prediction algorithm.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.22-30
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• 1989

Wave propagation is changed by the effect of shoaling, current-depth refraction and shelter-ing etc. To solve these problems. numerous models have been developed. In the present study, a coordinate system is proposed based on the wave ray equation with the wave number equation including diffraction effects . The governing equation for the study was derived from the mild slope wave equation in non-steady state, including current effects (Kirby, 1986a) and trans-formed into an orthogonal curvilinear coordinate system on the basis of the wave ray equation. To obtain a numerical solution, an explicit finite difference scheme was used, and solved by the relaxation method. This model was tested for various cases: Firstly a submersed circular shoal and a constant unit depth. Secondly a submerged elliptic shoal on a slope, and finally a breakwater harbour with obliquely incident waves on a slope. The model was found to simulate the experimental results and other theoretical results in wave height and wave angle fairy well, and the applicability of the model around an arbitrary shaped coastal structure was also verified. To demonstrate the general usefullness of the present approach , the model is to be applied to a field situation with a complex bed topography.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.212-221
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• 2016

In this study, characteristics of swell-like high waves in the East Sea were analyzed using observed wave data and predicted meteorological data from the National Oceanic and Atmospheric Administration (NOAA). And, the wave prediction system using the data from the NOAA has been established. Furthermore, the applicability of the system has been verified by comparing the predicted results with the corresponding observed data. For some case, there were two times of wave height increase and the second increase occurred in a calm weather condition on the coast which might cause casualties. The direction of wave energy propagation was estimated from observed wave data in February, 2008. Through comparison between the direction of wave energy propagation and the meteorological data, it turns out that the second increase of waves is originated from the seas between Russia and Japan which is far from the East Sea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.557-564
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• 2007

The effect of wave and current interactions on regular wave transformation over a submerged elliptic shoal is investigated based on numerical simulations of the Vincent and Briggs experiment [Vincent, C.L., Briggs, M.J., 1989. Refraction-diffraction of irregular waves over a mound. Journal of Waterway, Port, Coastal and Ocean Engineering, 115(2), pp. 269-284]. The numerical simulations are conducted by constituting two numerical model systems: a combination of SWAN(a wave model) plus SHORECIRC(a current model) and a combination of REF/DIF 1(a wave model) plus SHORECIRC. A time dependent phase-resolving wave-current model, FUNWAVE, is also utilized to simulate the experiment. In the simulations, the breaking-induced currents defocus waves behind the shoal and bring on a wave shadow zone that shows relatively low wave height distributions. The computed results of the two model systems agree better with the measurements than the computed results obtained by neglecting wave-current interaction do. However, it is found that the radiation stresses for standing waves are misevaluated in the wave models. In addition, the results of FUNWAVE show very good agreement with the measurements. The agreement indicates that it is necessary to take into account the effect of breaking-induced current on wave refraction when wave-breaking occurs over a submerged shoal.