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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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Journal DOI :
Korean Society of Coastal and Ocean Engineers
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Volume & Issues
Volume 14, Issue 4 - Sep 2002
Volume 14, Issue 3 - Sep 2002
Volume 14, Issue 2 - Jun 2002
Volume 14, Issue 1 - Mar 2002
Selecting the target year
Revaluation of Tsunami Risk at the Site of Ulchin Nuclear Power Plant
Lee, Haegyun ; Lee, Dae-Soo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 1~7
In the past, safety asessment on the site of Ulchin Nuclear Power Plants against tsunamis wascaried out with probable maximum earthquake magnitude and related tsunamigenic fault parameters. Recently,however, based on the seismic gap theory, some seismologists warned about earthquakes of larger magnitudesthan had been expected. In this study, we revaluated tsunami risk with a finite diference model based on linearand nonlinear shallow water equations. Firstly, we simulated the 3 tsunami and compared the calculated watersurface profile with the observed wave heights. Secondly, we evaluated the rise and drop of sea water level at thesite of Ulchin Nuclear Power Plant with fault parameters of the past 83, 3 tsunamis and some dangerous faults.Finaly, we showed that the coling water intake facility of Ulchin Nuclear Power Plants would be safelyoperated in disastrous tsunamis.
Wave Energy Absorption by a Circular Oscillating Water Column Device
Cho, Il-Hyoung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 8~18
In this paper, wave energy absorption of OWC(oscilating water column) device is analyzed. Theanalytic model consists of a partially immersed circular vertical cylinder open at its end and an air turbineconected with the air chamber. The boundary value problem is decomposed into scattering problem related toscatering by an incident wave in the absence of a pressure variation and radiation problem describing the flowdue to an oscillating pressure in the absence of an incident wave. By invoking the continuity of an air flow insidethe chamber, the oscillating presure in a chamber is derived. With oscilating pressure, the mean power absorbedby OWC device and the capture width are obtained. In numerical calculation, the induced volume flux acros theinternal fre surface of the chamber in the scatering and radiation problem and the maximum capture width arecompared with various design parameters such as radius and submergence depth of chamber and waveconditions. The maximum capture width obtained by choosing the optimal value of turbine constant occurs at thefirst resonant mode (Helmholtz mode) among the natural frequencies of a circular cylinder chamber.
Numerical Analysis on the Detemination of Hydraulic Charcteristics of Rubble Mound Breakerwater
Park, Hyunjoo ; Chun, Insik ; Lee, Dalsoo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 19~33
A numerical method to efficiently secure necesary design informations of the hydraulic character-istics of rubble mound breakwater was attempted here. The method combines the exterior wave field with theinterior wave field which is formulated incorporating porous media flow inside the breakwater. An approximatemethod based on the long wave assumption was used for the exterior wave field while a boundary elementmethod was used for the interior wave field. A hydraulic experiment was also performed to verify the validity ofthe numerical analysis. The numerical results were compared with experimental data and results from existingformulae. They generally agreed in both reflection and transmission coeficients. The calculated pore presuresalso showed a similar pattern with experimental data, even if they gave some significant diferences in theirvalues for some cases. The main cause of such diferences can be atributed to the strongly nonlinear wave fieldocuring on the frontal slope of the breakwater. The direct input of dynamic presures(measured from hydraulicexperiment) into the numerical method was suggested as a promising method to enhance the predictability ofpore pressures.
Transition Characteristics of Long Period Waves by Field Observation
Kim, Kyu Han ; Kim, Duk Joong ; Yoo, Hyung Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 34~40
In order to estimate the height of long period wave from character of deep water wave, fieldobservation is carried out thre wave gauge are aranged by a straight line from the seashore to offshore directionand the result is analyzed. In addition, the existing theory of the mechanism for long period wave producer isverified by field observation, and the relation between deep water wave and long period wave of shalow area isexamined. Observed long period wave is coincided with the existing theory for the most part. In order to ad thechange of time and space of long period wave, the height of long period wave is calculated by the compositionof long period wave in each position. As a result, the relation of long period wave and deep water wave ispresented more clear. Estimate formula is drew through them.
Digital Bathymetric and Topographic Data for Neighboring Seas of Korea
Choi, Byung Ho ; Kim, Kyeong Ok ; Eum, Hyun Min ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 41~50
An attempt has been made to establish digital bathymetric and topographic database in the form ofgrid point value(GPV) with an interval of one-minute horizontal space for a wide region of seas adjacent toKorean Peninsula and also with an interval of one-arcsecond for coastal seas of Korean Peninsula. Especialyterestrial and marine data fusion work using mean sea level as vertical datum plane has ben performed for one-arcsecond GPV dataset. It is believed that the compiled bathymetric dataset are reliable comparing with existingdataset so far and can be utilized for ocean simulations of intermediate scale proces and also detailed coastalinundation proces.
Long-Period Wave Oscillations in Sokcho Harbor and Cheongcho Lagoon(1. Field Measurements and Data Analyses)
Jeong, Weon Mu ; Park, Woo Sun ; Kim, Kyu Han ; Chae, Jang Won ; Kim, Ji Hee ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 51~64
To investigate long-period wave responses in Sokcho Harbor and Cheongcho lagoon, fieldmeasurements were made for long- and short-period waves and current velocities using a DirectionalWaverider, a ultrasonic-type wave gauge, four pressure-type wave gauges, and a current meter. From the dataanalysis, it was found that the Helmholtz resonant periods of Sokcho Harbor and Cheongcho lagoon are about13.6 and 54.5 minutes, respectively, and the dominant period of wave induced current in the passage betweenSokcho Harbor and Cheongcho lagoon is about 55.2 minutes which depends on Helmholtz resonant conditionof the Cheongcho lagoon. It was also found that the energy level of the far-infra-gravity waves during stormconditions is very high compared with that during calm sea conditions. To investigate relationships betweenfar-infra-gravity waves and short-period waves at offshore station, regression analyses were carried outespecially for .) heights, 2) periods, 3) direction and height, 4) height and period between short-and far-infra-gravity waves, respectively. The results showed that the long-period wave height is highly correlated with theshort-period wave height. However, no special trend was found for the other relations. In the future far-infra-gravity wave heights on return period around Sokcho Harbor region can be suggested by using extreme valueanalyses of long term measured data.
An Investigation-Study on the Erosion at Hak-Dong Gravel Beach
Ham, Gye Un ; Kim, Jin Hong ; Jang, Dae Jeong ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 65~75
The changes of sea bottom configuration, which may cause the coastal disasters, have beenconsidered as social problems. It is obvious that the beach deformation is atributable to the sediment transportasociated with erosion and siltation in coastal areas such esturies, chanel and harbors. The prediction methodand countermeasures for them, however, are not on the level of satisfaction, which indicates that make efortsshould be made on developing them. Groin was constructed at Hak-Dong gravel beach to embark ship at 196,as a result region of right of groin, severe erosion of beach is proceeding til now 19. In this study, based on thefield measurements, involved the one-line theory model which was selected for the prediction of shorelinechange to prepare coastal protection methods of Hak-Dong gravel beach. Author found that the storagedsediment estimation model by Sonu and Beek(1971) is useful model at the Hak-Dong gravel beach by the use oftopographical survey data from September, 1998 to September, 1999.
Harbor Tranquility Analysis with the Reflection - Transmission Boundary Condition of Floating Breakwaters
Chun, Insik ; Choi, Minho ; Sim, Jaesul ; Oh, Beongcheol ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 76~85
The floating breakwater generaly has an excelent water exchanging capability, but with somelowering harbor tranquility due to the wave transmission underneath floating body. In the initial stage of design,it is thus required to investigate several alternatives of breakwater layout for their performance of harbortranquility. The present study aims to formulate a sort of reflection - transmission boundary condition of floatingbreakwater so that the existing numerical method using time dependent mild slope equation can stil be appliedto the case of floating breakwaters. The two and thre dimensional tests were each performed to demonstrate theperformance of the boundary condition. It was found that the reflection and transmission characteristics aroundthe breakwater were wel reproduced by the boundary condition. Finaly, the reflection-transmision boundarycondition were applied to a floating breakwater installed in an imaginary harbor with an irregular shape andbotom topography. The results surely showed that the present numerical method can effectively used in practicalworks related to the real sea construction of floating breakwaters.
A Note on the Proper Size of a Finite Element for Analysis of Harbor Resonance Problems
Jeong, Weon Mu ; Park, Woo Sun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 14, issue 1, 2002, Pages 86~93
In this study, numerical experiments were performed to decide the proper size of a finite elementfor the analysis of harbor resonance problems. Various sizes of finite elements were considered from 1/3 to 1/60of wavelength to model a fully opened rectangular harbor. Through the numerical results, the proper number offinite elements per wavelength were revealed to be nine within two percents errors allowed in resonant periodand amplification ratio, while twelve within one percent error. It was found that eror rates of resonant periodsdecrease linearly, while those of amplification ratio decrease with oscilating form as the size of an elementdecreases. The eror of amplification ratio increases more rapidly than that of resonant period in case of elementnumbers below nine.