Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Korean Society of Coastal and Ocean Engineers
Journal Basic Information
Journal DOI :
Korean Society of Coastal and Ocean Engineers
Editor in Chief :
Volume & Issues
Volume 15, Issue 4 - 00 2003
Volume 15, Issue 3 - 00 2003
Volume 15, Issue 2 - 00 2003
Volume 15, Issue 1 - 00 2003
Selecting the target year
On an Analysis of Reflection Coefficients by a Partially Immersed Slotted Plate with a Back Wall
Cho, Il-Hyoung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 143~150
Based on the eigenfunction expansion method, the interaction between monochromatic waves and a partially immersed slotted plate with a back wall has been investigated. Analytical results show that the reflection coefficients by a partially immersed slotted plate depend on the porosity, immersed depth, chamber width, incidence angle and wave frequency. It is found that the reflection coefficient has minimum value within entire frequency range when the porosity has optimal value 0.1. Comparison between the analytical results and the experimental results(Zhu,2001) of reflection coefficients is made for various chamber widths, immersed depths and wave periods with good agreement. The present analytic method can account adequately for energy dissipation caused by flow separation behind a slotted plate and provide the design informations for the construction of slit caisson breakwater.
Numerical Simulation of Velocity Fields and Vortex Generation around the Submerged Breakwater on the Sloped Bottom
Heo, Dong-Su ; Kim, Do-Sam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 151~158
The study of velocity fields and vortex generation around the submerged breakwater can be utilizedas materials related to understanding of wave disipation mechanism, sediment transport, and stability ofstructure. In the present study, two-dimensional numerical wave flume, based on the VOF method to trace fresurface, developed by Kim et al.(2001, 2002) was used to numericaly simulate velocity fields and vortexgeneration around the impermeable submerged breakwater instaled at the uniform botom. Especialy, thecharacteristics of vortex generation due to the geometry of the structure and incident wave conditions areexamined through the analysis of averaged-velocity fields around the impermeable submerged breakwater. Fromthe numerical simulations, it is confirmed that a counter clockwise vortex is formed in front of the structure anda clockwise vortex develops behind the structure. Also, incident wave height and period have an sensitive effecton the strength of vortex.
Hybrid Element Model for Wave Transformation Analysis
Jeong, Tae-Hwa ; Park, U-Seon ; Seo, Gyeong-Deok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 159~166
In this study, we develop a finite element model to directly solve the Laplace equation whilekeping the same computational eficiency as the models based on the extended mild-slope equation which hasben widely used for calculation of wave transformation in shallow water. For this, the computational domain isdiscretized into finite elements with a single layer in the vertical direction. The velocity potential in the elementis then expresed in terms of the potentials at the nodes located at water surface, and the Galerkin method is usedto construct the numerical model. A common shape function is adopted in horizontal direction, and the cosinehyperbolic function in vertical direction, which describes the vertical behavior of progressive waves. The model wasdeveloped for vertical two-dimensional problems. In order to verify the developed model, it is applied to verticaltwo-dimensional problems of wave reflection and transmission. It is shown that the present finite element model iscomparable to the models based on extended mild-slope equations in both computational efficiency and accuracy.
Laboratory Experiments on Reflection of Regular Waves due to Submerged Braekwaters
Lee, Jong-In ; Kim, Young-Taek ; Cho, Yong-Sik ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 167~175
In this study, reflection of regular waves over a train of submerged breakwaters is experimentallyinvestigated. Wave reflection from various-shaped submerged breakwaters is examined by using laboratoryexperiment and eigenfunction expansion method. Shapes of submerged breakwaters are rectangular, triangular,trapezoidal and semi-circular. Laboratory measurements are compared with predicted coefficients obtained fromthe eigenfunction expansion method. Although measured coefficients are slightly smaller than predicted ones,the overall agreement is very god. The present study can provide a criterion for the proper choice of a shape ofsubmerged breakwaters in practical situation.
Local Scour at a Submarine Pipelines on Slope Beach
Hwang, Hyon-Ku ; Kim, Kyoung-Ho ; Yeun, Ju-Heum ; Oh, Hyoun-Sik ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 176~185
In order to ensure that submarine pipelines are stable and functional during their project lives,atention must be paid to possibility of their local scouring. When a pipeline is placed on an erodible bed, scourwill develop and cause the spanning of the pipeline. If they were destroyed partially or fuly, it might causeenormous restoration expenses and contamination of sea water. This paper aims at examining the characteristicsof the scour and the prediction of the local scour depths around the submarine pipelines. The pipelines on themodel beach with the uniform slope are placed, and the local scour depths around the pipelines are obtainedacording to the various wave stepneses. Using the experimental results, some parameters needed for analysesare calculated. Finaly, empirical equations of the scour depth around the pipelines are suggested through thecorrelation analyses betwen the relative scour depth, the KC number and Modified Ursel number.
Comparison of Accuracy of Stability Formulas for Breakwater Armor Stones
Suh, Kyung-Duck ; Yoo, Dong Hoon ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 186~189
Various empirical formulas have been developed to describe the stability of breakwater armorstones. The Hudson formula is known to have needs to be refined in many ways, but it is most widely usedbecause of its simplicity. The van der Meer formula is sometimes used for the cross-check, but it is not verypopularly used due to its complexity and the uncertainty of the relevant parameters. Recently, on the other hand,Yoo(2003) proposed a formula of a simple form using a new non-dimensional number which is caled actionslope (abbreviated as Yo formula hereinafter). In this study, in order to provide coastal engineers with someidea of the use of these formulas, their acuracies were estimated by comparing with the experimental datareported by van der Meer in 1987 and 198. It was found that the van der Mer formula showed the highestacuracy, while the Hudso formula of very low acuracy need considered judgment on its use. On the otherhand, the Yoo formula of slightly lower acuracy but simpler expresion than the van der Meer formula seems tobe able to be used in enginering practice if a slightly higher safety factor is taken.
Generation Method of the Rectangular Grid Information for Finite Difference Model
Jeong, Sin-Taek ; Jo, Beom-Jun ; Kim, Jeong-Dae ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 15, issue 3, 2003, Pages 190~195
For many coastal problems, such as wave transformation, tidal circulation, sediment transports anddifusion phenomena, we resort to numerical techniques. The representative numerical techniques are the methodof finite diferences and finite elements. The approximate algebraic equations, refered to as finite diferenceequations(FDEs), are subsequently solved at discrete grid points within the domain of interests. Therefore, a setof grid points within the domain, as well as the boundaries of the domain, must be specified. The generation ofgrids for FDEs, with uniform spacing, is very simple compared to that of finite elements. However, within a verycomplex domain, there are few grid generation tools we can use conveniently. Unfortunatey, most of thecommercial grid generation programs are developed only for finite element method. In this paper, grid generationmethod using digitizer, with uniform rectangular spacing, are introduced in detail. Didger and Surfer programsby Golden Software are necessary to produce comparatively acurate and simple depth data.