• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.163-169
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• 2012

In this paper, model test on the Tapdong's revetment at Jeju-si has been conducted to figure out the causes of frequent occurrence of wave overtopping and to suggest the action plan. In the model test, the reflection coefficients were measured according to the change of wave periods for with and without armor stones. Also, the wave overtopping rate and the wave pressures inside revetment structure for 4 types of upper block were estimated for various wave heights and wave periods, which are chosen based on the NE design wave with 50 year return period. It is found that the increase of the upper structure's height and the modification of the curved protruding shape are effective in reducing the overtopping rate.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.373-376
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• 2006

In general, a method for generating irregular wave by combination of component waves obtained from linear wave theory is widely used. In these method, however, mean water surface elevation is rising from time to time because of nonlinear effect of wave. In this study, for the rising problem of mean water surface elevation and stabilization of calculation from time to time, mass transport velocity for horizontal velocity at wave source position is considered. The rising problem of mean water surface elevation is checked by comparing calculated wave profile from numerical technique proposed in this study with target wave profile at wave source position in numerical wave tank by using CADMAS-SURF code. And, by generating irregular wave, the validity of wave overtopping rate estimated from this numerical analysis is discussed by comparing computed results with measured results in hydraulic model experiments for vertical seawall located on a sloping sea bottom. As a results, the computations are validated against the previously experimental results by hydraulic model test and numerical results of this study and a good agreement is observed. Therefore, numerical technique of this study is a powerful tool for estimating wave overtopping rate over the crest of coastal structure.

• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.65-70
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• 2009

The hybrid numerical model is developed by combining BEM that can calculate the wave motion rapidly under the potential theory and CADMAS-SURF that solves Navier-Stokes equations for the free surface variation near the structure, In the hybrid model the calculation of wave motion in a wide field of wave reflection for deep water area is conducted by BEM but for shallow water area by CADMAS-SURF. Especially the hybrid model can calculate random wave motions for long term period more rapidly with almost similar accuracy than the calculation of wave motion which was carried out by CADMAS-SURF only. In this study the coupling model was applied to the calculation of the strong nonlinear wave motion such as wave runup and overtopping at the coastal structure on the mild-slope bottom and the results of numerical model were compared with the Toyosima's experiments of regular wave runup and Goda's design diagram of ramdom wave overtopping, respectively.

• Journal of Navigation and Port Research
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• v.45 no.6
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• pp.325-332
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• 2021

As commercial and residential areas are actively developed around the coastal area with excellent scenery, installing coastal structures such as seawalls and breakwaters is continuously increasing to secure safe coastal regions. Additionally, the increase in the intensity of natural disasters due to climate change may cause higher incident waves than in the past, which may further aggravate the damage caused by wave overtopping. In this study, compared to the existing vertical seawall, we investigated the effect of wave overtopping reduction of a recurved seawall, which actively reflects the incoming waves, through the hydraulic model test. As a result of the hydraulic model experiment, it was confirmed that there was an effect of up to 92.4% of wave overtopping reduction in average compared to the vertical seawall and structures covered with armor blocks.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.881-891
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• 2020

In recent years, large-scale development of coastal areas has caused the loss of many lives and extensive property damage in coastal areas, due to wave overtopping caused by high-wave invasion and strong typhoons. However, coastal inundation studies considering the characteristics of domestic coastal areas are insufficient. This study is a methodology study that aimed to reproduce inundation of surge and wave complex elements by applying the ADCSWAN (ADCIRC+SWAN) and FLOW-3D models. In this study, the boundary data (sea level, wave) of the FLOW-3D model was extracted using the ADCSWAN (ADCIRC+SWAN) model and applied as the input value of the FLOW-3D model and a reproduction was created of the Flooding due to surge and overtopping in Busan Marine City when the typhoon Chaba passed. In addition, the existing overtopping empirical equation and the overtopping calculated by the FLOW-3D model were compared, and for coastal inundation, a qualitative verification was performed using the Inundation Trace Map of Land and Geospatial Informatrix Corporation, and the effectiveness of this study was reviewed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.6
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• pp.290-302
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• 2022

In this study, it was examined for the reduction of wave overtopping and water level fluctuation in front of the revetment when applying a reinforcement method to revetment where wave overtopping occurs. As a result of the study, in the case of the cross-sectional experiment. more than 70% of the wave overtopping reduction effect depending on the reinforcement conditions was occurred, and it was analyzed that the result increases by about four times or more in the comparison with the 3d test. The average water level in front of the revetment was lowered when a low crest structure was not installed. and there was a tendency to rise under the condition of low crest structures installed. In the comparison with the wave basin test, there was a difference of about 0.5 to 0.6 times when a low crest structure was not installed, and it was increased by 5.5 times after low crest structures were installed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.154-158
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• 2000

Hydraultic experiments were performed in 2-D were flume to investigate the stability o the breakwaters, the destruction of armor blocks and overtopping under irregular wave attack on the structures armored by \`Core-Loc\`. Overtopping rate and stability were examined and compared when armored by Core-Loc and by T.T.P. Results shows both type of blocks are stable and overtopping rates are similar in the adopted experimental condition. Therefore Core-Loc can replace some portion of T.T.P. which is uniquely used in Korea. Further integrated experimental data with Core-loc are need for destruction mechanism or overtopping rate.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.113-118
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• 2002

Wave overtopping is one of the most important hydraulic responses of breakwater because it significantly affects its functional efficiency, the safety of transit and mooring on the rear side, wave transmission in the sheltered area, rear side armor stones and to some extent, the structural safety itself. The hydrodynamic characteristics of low crest breakwater by the overtopping rate can be summarized as follows: 1. It is better to use maximum overtopping rate than to use mean overtopping rate for design of coastal structures. 2. Maximum overtopping rate was increase with wave steepness (between 0.01 and 0.02). 3. Overtopping rate is decreased when relation length of berm was over wave length.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.61-67
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• 2019

Recently, a perforated caisson breakwater with turning wave blocks was developed to improve the water affinity and public safety of a rubble mound armored by TTP. In this study, hydraulic model tests were performed to examine the hydraulic performance of a non-porous caisson and new caisson breakwater with perforated blocks for attacking waves in a small fishery harbor near Busan. The model test results showed that the new caisson was more effective in dissipating the wave energy under normal wave conditions and in reducing the wave overtopping rates under design wave conditions than the non-porous caisson. It was found that the horizontal wave forces acting on the perforated caisson were slightly larger than those on the non-porous caisson because of the impulsive forces on the caisson with the turning wave blocks.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.286-304
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• 2017

In this study, we proposed a new-type of circular perforated caisson breakwater consisting of a bundle of latticed blocks that can be applied to a small port such as a fishing port, and numerically investigated the hydraulic characteristics of the breakwater. The numerical method used in this study is OLAFOAM which newly added wave generation module, porous media analysis module and reflected wave control module based on OpenFOAM that is open source CFD software published under the GPL license. To investigate the applicability of OLAFOAM, the variations of wave pressure acting on the three-dimensional slit caisson were compared to the previous experimental results under the regular wave conditions, and then the performance for irregular waves was examined from the reproducibility of the target irregular waves and frequency spectrum analysis. As a result, a series of numerical simulations for the new-type of circular perforated caisson breakwaters, which is similar to slit caisson breakwater, was carried out under the irregular wave actions. The hydraulic characteristics of the breakwater such as wave overtopping, reflection, and wave pressure distribution were carefully investigated respect to the significant wave height and period, the wave chamber width, and the interconnectivity between them. The numerical results revealed that the wave pressure acting on the new-type of circular perforated caisson breakwaters was considerably smaller than the result of the impermeable vertical wall computed by the Goda equation. Also, the reflection of the new-type caisson breakwater was similar to the variation range of the reflection coefficient of the existing slit caisson breakwater.