• Proceedings of the KSME Conference
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• 2002.08a
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• pp.205-208
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• 2002

Numerous studies have been performed to develop an analytical model that can predict the reflection of regular or irregular waves from a perforated-wall caisson breakwater. Though such irregular wave models as Suh et at. (2001) become available, regular wave models are still in extensive use because of their simplicity. In the present study, using the regular wave model of Fuggazza and Natale(1992), the reflection of irregular waves from a perforated-wall caisson breakwater was calculated in several different methods. First, the regular wave model was re-validated by the hydraulic model tests. Though the model somewhat over-predicted the reflection coefficients at larger values and under-predicted them at smaller values, overall agreement was pretty good between calculation and measurement. Then, the regular wave model was applied to calculate the irregular wave reflection in the experiments of Suh et at.(2001) and Bennett et al. (1992). In applying the regular wave model to irregular wave reflection, several different methods were used. The results showed that it is the most reasonable to use the regular wave model repeatedly for each frequency component of the irregular wave specuum with the root-mean-squared wave height for all the frequencies .

• Journal of Navigation and Port Research
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• v.31 no.7
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• pp.579-587
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• 2007

Samchunpo(Sin Hyang) Harbor is located in the bay of Sa Chun, the central south coast of Korean peninsula. The harbor and coastal boundaries have been protecting by natural coastal islands and shoals. Currently, The Sin Hyang harbor needs maintenance and renovation of the sheltered structures against the weather deterioration and typhoon damages. Consequently to support this, the calculation of accurate design wave through the typhoon wave attack is necessary. In this study, calculation of incident wave condition is simulated using steady state spectrum energy wave model(wide area wave model) from 50 years return wave condition. And this simulation results in wide offshore area were used for the input of the extended mild slope wave model at the narrow coastal area. Finally, the calculation of design wave at Sin Hyang harbor entrance was induced by Boussinesq wave model(detail area wave model) simulation. The numerical model system was able to simulate wave transformations from generation scale to shoreline or harbor impact. We hope these results will be helpful to the engineers doing placement, design, orientation, and evaluation of a wide range of potential solutions in this area.

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.41-52
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• 1995

the necessity of development of the Nearshore zone greatly emphasis in recent years. In the wave deformation model, we can get the wave height and wave direction using the hyperbolic mild slope equation considered the reflection wave. Radiation Stress the driving force of flow was calculated by the Watanabe and Maruyama who proposed on the partial standing wave. In the surf zone, applying the Izumiya and Horikawa's turbulent model considered the bottom friction and energy dissipation, we compared and examined with the Numerical model and Hydraulic test result of Watanabe and Maruyama. This model results obtained for Jin-ha Beach agreed well with the Numerical results. This model is expected so helpful to solve the prediction of the wave deformation problems in the development of the Nearshore zone in the future.

• Journal of Korean Port Research
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• v.12 no.2
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• pp.269-280
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• 1998

A Wave-induced current model is developed in our study and this model is composed with wave transform model and current model. Two types of wave model are used in our study one is Copeland(1985) type which is applied in the offshore region and the other is Watanabe and Maruyama(1984) type which is applied in the surf zone. The depth-integrated and time-averaged governing equation of an unsteady nonlinear form is used in the wave induced current model. Lateral mixing radiation stresses surface and bottom stresses are considered in our current model. Copeland’s(1976) is used as a surface friction formula. Numerical solutions are obtained by Leendertse scheme and compared with Noda’s(1974) experimental results for the uniform slope coastal region test and Nishimura & Naruyama’s (1985) experimental results and numerical simulation results for the detached breakwater. The results from our wave model and wave model and wave-induced current model show good agreements with the others and also show nonlinear effects around the detached breakwater. The model in this study can be applied in the surf zone considering the friction stresses.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.70-86
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• 2015

Short crested waves play an important role for planning and design of harbours. In this context a numerical simulation is carried out to evaluate wave tranquility inside a real harbour located in east coast of India. The annual offshore wave climate proximity to harbour site is established using Wave Model (WAM) hindcast wave data. The deep water waves are transformed to harbour front using a Near Shore spectral Wave model (NSW). A directional analysis is carried out to determine the probable incident wave directions towards the harbour. Most critical threshold wave height and wave period is chosen for normal operating conditions using exceedence probability analysis. Irregular random waves from various directions are generated confirming to Pierson Moskowitz spectrum at 20m water depth. Wave incident into inner harbor through harbor entrance is performed using Boussinesq Wave model (BW). Wave disturbance experienced inside the harbour and at various berths are analysed. The paper discusses the progresses took place in short wave modeling and it demonstrates application of wave climate for the evaluation of harbor tranquility using various types of wave models.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.189-199
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• 1998

Wave-induced current model is developed in our study and this model is composed with wave transform model and current model. Two types of wave model are used in our study, one is Copeland(1985) type which is applied in the offshore region and the other is Watanabe and Maruyama(1984) type which is applied in the surf zone. The depth-integrated and time-averaged governing equation of an unsteady nonlinear form is used in the wave induced current model. Lateral mising, radiation stresses, surface and bottom stresses are considered in our current model. Copeland's(1985) relult is used to calculate radiation stress and Berkmeir & Darlymple's(1976) is used as a surface friction formula. Numerical solutions are obtained by Leendertse scheme and compared with Noda's(1974) experimental results for the uniform slope coastal region test and Nishimura & Maruyama's(1985) experimental relults and numerical simulation results for the detached breakwater test. The results from our wave model show good agreement with the others and also show nonlinear effects around the detached breakwater. Wave induced current model is developed in this study and this model shows nonlinear effects around the detached breakwater and can be applied in the surf zone and also consider the friction stresses.

• Ocean and Polar Research
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• v.43 no.3
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• pp.179-192
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• 2021

In this study, an integrated wave model from global to coastal scales was developed to improve the operational wave prediction performance of the Korean Meteorological Administration (KMA). In this system, the wave model was upgraded to the WaveWatch III version 6.07 with the improved parameterization of the source term. Considering the increased resolution of the wind input field and the introduction of the high-performance KMA 5^th Supercomputer, the spatial resolution of global and regional wave models has been doubled compared to the operational model. The physical processes and coefficients of the wave model were optimized for the current KMA global atmospheric forecasting system, the Korean Integrated Model (KIM), which is being operated since April 2020. Based on the sensitivity experiment results, the wind-wave growth parameter (β_max) for the global wave model was determined to be 1.33 with the lowest root mean square errors (RMSE). The value of β_max showed the lowest error when applied to regional/coastal wave models for the period of the typhoon season when strong winds occur. Applying the new system to the case of August 2020, the RMSE for the 48-hour significant wave height prediction was reduced by 13.4 to 17.7% compared to the existing KMA operating model. The new integrated wave prediction system plans to replace the KMA operating model after long-term verification.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.51-62
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• 2012

According to the Lighthill and Whitham's shock wave model, a shock wave exists even in a homogeneous speed condition. They referred this wave as unobservable- analogous to a radio wave that cannot be seen. Recent research has attempted to identify how such a counterintuitive conclusion results from the Lighthill and Whitham's shock wave model, and derive a new asymptotical shock wave model. The asymptotical model showed that the shock wave in a homogenous speed traffic stream is identical to the ambient vehicle speed. Thus, no radio wave-like shock wave exists. However, performance tests of the asymptotical model using numerical values have not yet been performed. We investigated the new asymptotical model by examining the implications of the new model, and tested it using numerical values based on a test scenario. Our investigation showed that the only difference between both models is in the third term of the equations, and that this difference has a crucial role in the model output. Incorporation of model parameter${\alpha}$ is another distinctive feature of the asymptotical model. This parameter makes the asymptotical model more flexible. In addition, due to various choices of ${\alpha}$ values, model calibration to accommodate various traffic flow situations is achievable. In Lighthill and Whitham's model, this is not possible. Our numerical test results showed that the new model yields significantly different outputs: the predicted shock wave speeds of the asymptotical model tend to lean toward the downstream direction in most cases compared to the shock wave speeds of Lighthill and Whitham's model for the same test environment. Statistical tests of significance also indicate that the outputs of the new model are significantly different than the corresponding outputs of Lighthill and Whitham's model.

• Journal of Ocean Engineering and Technology
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• v.35 no.4
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• pp.273-286
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• 2021

In recent years, as human casualties and property damage caused by hazardous waves have increased in the East Sea, precise wave prediction skills have become necessary. In this study, the Simulating WAves Nearshore (SWAN) third-generation numerical wave model was calibrated and optimized to enhance the accuracy of winter storm wave prediction in the East Sea. We used Source Term 6 (ST6) and physical observations from a large-scale experiment conducted in Australia and compared its results to Komen's formula, a default in SWAN. As input wind data, we used Korean Meteorological Agency's (KMA's) operational meteorological model called Regional Data Assimilation and Prediction System (RDAPS), the European Centre for Medium Range Weather Forecasts' newest 5th generation re-analysis data (ERA5), and Japanese Meteorological Agency's (JMA's) meso-scale forecasting data. We analyzed the accuracy of each model's results by comparing them to observation data. For quantitative analysis and assessment, the observed wave data for 6 locations from KMA and Korea Hydrographic and Oceanographic Agency (KHOA) were used, and statistical analysis was conducted to assess model accuracy. As a result, ST6 models had a smaller root mean square error and higher correlation coefficient than the default model in significant wave height prediction. However, for peak wave period simulation, the results were incoherent among each model and location. In simulations with different wind data, the simulation using ERA5 for input wind datashowed the most accurate results overall but underestimated the wave height in predicting high wave events compared to the simulation using RDAPS and JMA meso-scale model. In addition, it showed that the spatial resolution of wind plays a more significant role in predicting high wave events. Nevertheless, the numerical model optimized in this study highlighted some limitations in predicting high waves that rise rapidly in time caused by meteorological events. This suggests that further research is necessary to enhance the accuracy of wave prediction in various climate conditions, such as extreme weather.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.04a
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• pp.75-81
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• 2000

Water waves propagate over irregular bottom bathymetry are transformed by refraction, diffraction, shoaling, reflection etc. Principal factor of wave transform is bottom bathymetry, but in case of current field, current is another important factor which effect wave transformation. The governing equation of this study is develop as wave-current equation type to investigate the effect of wave-current interaction. This wave-current model was applied to the Kwangan beach which is located at Pusan. The numerical simulation results of this model show the characteristics of wave transformation and flow pattern around the Kwangan beach fairly well.