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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Coastal and Ocean Engineers
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Korean Society of Coastal and Ocean Engineers
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Volume & Issues
Volume 21, Issue 6 - Dec 2009
Volume 21, Issue 5 - Oct 2009
Volume 21, Issue 4 - Aug 2009
Volume 21, Issue 3 - Jun 2009
Volume 21, Issue 2 - Apr 2009
Volume 21, Issue 1 - Feb 2009
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Comparison between Variational Approximation and Eigenfunction Expansion Method for Wave Transformation over a Step Bottom
Seo, Seung-Nam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 91~107
In order to compute linear wave transformation over a single step bottom, both variational approximation and eigenfunction expansion method are used. Both numerical results are in good agreement for reflection and transmission coefficients, surface displacement respectively. However x velocity profiles at the boundary of step are seen to be different to each other even though x velocity matching condition is used.
A Study on Wave Transformation Analysis using Higher-Order Finite Element
Jung, Tae-Hwa ; Lee, Jong-In ; Kim, Young-Taek ; Ryu, Yong-Uk ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 108~116
The present study introduces a Legendre interpolation function which is capable of analyzing wave transformation effectively in a finite element method. A Lagrangian interpolation function has been mostly used for a finite element method with a higher-order interpolation function. Although this function has an advantage of giving an accurate result with less number of elements, simulation time increases. Calculation time can be reduced by mass lumping, whereas the accuracy of solution is lowered. In this study, we introduce a modified Lagrangian interpolation function, Legendre cardinal interpolation, which can reduce simulation time with keeping up favorable accuracy. Through various numerical simulations using a Boussinesq equations model, the superiority of the Legendre cardinal interpolation function to a Lagrangian interpolation function was shown.
Solution Comparisons of Modified Mild Slope Equation and EFEM Plane-wave Approximation
Seo, Seung-Nam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 117~126
In order to test the accuracy between the modified mild slope equation (MMSE) without evanescent modes and the plane-wave approximation (PA) of eigenfunction expansion method, various numerical results from both models are presented. In this study, analytical solutions of two models are employed, one based on the MMSE derived by Porter (2003) and the other on the scatterer method of PA by Seo (2008a). Judging from direct comparisons against existing results of rapidly varying topography, the PA model gives better predictions of the wave propagation than the MMSE model.
Wave Damping Rate Over Multi-layer Permeable Bed of Finite Depth
Suh, Kyung-Duck ; Do, Ki-Deok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 127~135
Reid and Kajiura(1957) has studied on the wave damping rate over a permeable bed of infinite depth. In this study, wave damping rate over a permeable bed of finite depth is derived by linear wave theory. It is then extended to derive wave damping rates over a double or triple layer, each of which consist of different material. Applying the wave damping rate to the mild slope equation, the wave transmission coefficient over a permeable bed has been calculated. The model has been certificated by comparing with the result of Flaten and Rygg(1991)'s integral equation method in the case of a single-layer bed.
Assessment Manual for Optimization of Structural Scale of Stone and Gabion at the Final Closure of Sea Dike -I. Verification of Theories and Models-
Song, Hyun-Gu ; Kim, Jong-Kyu ; Hwang, In-Chan ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 136~144
This paper focuses on the attempt to manual application for optimization structural scale of stone and Gabion at the closing gap of sea dike. The manual was developed through hydraulic model experiment that measured the critical velocity of sill-crest, bottom protection and dam-face at the final closure of Saemangeum sea dike, and through the comparison and verification of critical velocity for each scale calculated by existing empirical formula. Also, the critical velocity when rocks are used together with gabion is measured to add to the manual, which is an initial attempt that had not been executed before. The manual proposes the appropriate structural scale according to the measured critical velocity per day during the final closure period of Saemangeum sea dike, and its application was appraised highly after the completion of the final closing.
Assessment Manual for Optimization of Structural Scale of Stone and Gabion at the Final Closure of Sea Dike -II. Application at the actual site-
Song, Hyun-Gu ; Kim, Jong-Kyu ; Hwang, In-Chan ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 145~153
This research utilized the manual to calculate the structural scale of stone and gabion, which was developed through comparison and verification of the results drawn by hydraulic model experiment and existing empirical formula. Appropriate structural scale of stone according to the construction site when the critical velocity was exceeded, utilizing the previously expected and recorded data on current velocity per day and per hour during the final closure period for Saemangeum sea dike. Also, the scale of rocks was presented, considering the altercation in water depth according to the construction. The developed manual offered appropriate rate of mixed use of stone and gabion that suits various flow velocities, which will minimize any loss of stone-gabion and contribute to successful final closure, and proved the utility and application of the manual.
Variation of Incident Wave Angle in the Surf Zone Observed from Digital Videos
Yoo, Je-Seon ; Shin, Dong-Min ; Cho, Yong-Sik ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 154~163
Incident wave angles are conventionally estimated by the directional spectrum analysis of wave data collected from in-situ sensors. The in-situ measurements are limited in monitoring incident wave angles in the wide surf zone, since the techniques are typically expensive, labor-intensive, and point-measuring. In this study, estimation of incident wave angles using wave crest features captured in digital video imagery is proposed to observe incident wave directions over the surf zone. Line signatures of wave crests having high image pixel intensities are extracted by moving an interrogation window to identify high intensity pixels in sequential video images. Wave angles are computed by taking the first derivative of the extracted crest signatures, i.e. local slope of the crest signatures in the two-dimensional physical plane. Compared to the wave angle estimates obtained by the directional spectrum analysis, video-based wave angle estimates show good agreements in general.
Applicability on Inundation for Hydrodynamic Models adopting Moving Boundary Scheme
Park, Seon-Jung ; Kang, Ju-Whan ; Moon, Seung-Rok ; Yoon, Jong-Tae ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 164~173
MIKE21, a commercial hydrodynamic model, was applied at the Masan Bay to evaluate the model's applicability of simulating the inundation phenomena. A storm surge/inundation model which adopts overflow computation scheme was applied together for comparison. The results of both models show correspondence with not only observed inundation area but also inundation water depth to prove their ability as inundation models. Especially, the accuracy of the MIKE21 model, which just adopts wetting/drying scheme, does not seem to be behind the inundation model. Moreover, an inundation simulation of the virtual MAEMI which was generated at preceding study, was conducted. The inundation area of the virtual MAEMI is similar to that of the real MAEMI, but inundation water depth is deeper than the real MAEMI.
A Preliminary Study on the Status and Improvement of the Environmental Assessment of Coastal Erosion in Korea
Cho, Kwang-Woo ; Maeng, Jun-Ho ; Shin, Hyun-Hwa ; Joo, Yong-Jun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 174~181
The present study is a preliminary attempt to effectively incorporate the environmental issue of coastal erosion into the environmental assessment process of Korea. We assess the status of the environmental assessment on coastal erosion for the previous development plans and provide potential directions for the improvement. The considerable project plans should be screened for the impact of coastal erosion, which occupies about 20% of the total project plans reviewed, and the ratio increased with project scale. In addition to screening process, most process including scoping, baseline study, impact assessment, and follow-up need to be improved. The potential directions of improvement are provided in terms of appropriate guideline development, employment of cumulative impact assessment, follow-up improvement and rearrangement of the preparation regulation of environmental assessment. Emphasis is given for follow-up process to review post-monitoring period, to employ science compensation, and to consider the establishment of relevant institution. Final suggestion is made for the establishments of comprehensive national plan to manage coastal erosion and streamlined environmental process from strategic to project levels based on the national plan.
Internal Wave-Maker using Momentum Source Term of RANS Equation Model
Choi, Jun-Woo ; Ko, Kwang-Oh ; Yoon, Sung-Bum ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 182~190
For RANS equation model using VOF scheme Lin and Liu (1999) developed internal wave-maker method to generate target wave trains by using designed mass source functions of the continuity equation. By using this method studies on various numerical wave experiments has been achieved without the problem caused by wave reflection due to an external wave-maker. In this study, the wave-maker method to generate target wave trains by using a momentum source function was proposed. The computational results obtained by applying the mass and momentum source functions into FLUENT were compared with each other. To see its applicability, the hydraulic experiment of Luth et al. (1994) were numerically simulated and their measurements are compared with the computations, and the vertical variations of computed results were shown and investigated.
A Study on the Fatigue Strength of the Reinforced Concrete Beams Repaired with Glass Fiber Reinforced Polymer(GFRP) Bar and Glass Fiber Steel Plate(GSP)
Kim, Jae-Young ; Kim, Chung-Ho ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 191~195
After developing the pre-crack to simulate a damaged reinforced concrete beam, fatigue test was conducted on the beam repaired by GFRP Bar and GSP embedded method. In the result of fatigue test, most residual displacement and crack of the experimental beams occurs in the early loading cycle and an increasing rate of these due to number of cycles were insignificant. Comparing with a non-repaired beam, a static strength of the repaired beam greatly increased, but fatigue strength decreased. In S-N curves, fatigue strength of the beam repaired by GFRP Bar and GSP was 58%, 52% of the static strength respectively.
Wave Responses of Buoyant Flap-typed Storm Surge Barriers - Numerical Simulation
Jeong, Shin-Taek ; Ko, Dong-Hui ; Park, Woo-Sun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 2, 2009, Pages 196~208
In this paper, wave responses of buoyant flap-typed storm surge barriers was studied numerically. Wave motions were modeled by using a linear potential wave theory, and behaviors of structures were represented as a Newton's 2nd law of motion. The near field region of the fluid was discretized as conventional quadratic iso-parametric elements, while the far field was modeled as infinite elements. Comparisons with the results from hydraulic model tests show that the present model gives good results. By using the model, the applicability of a buoyant flap-typed storm surge barrier in Masan bay was investigated considering field environmental conditions.