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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 23, Issue 6 - Dec 2011
Volume 23, Issue 5 - Oct 2011
Volume 23, Issue 4 - Aug 2011
Volume 23, Issue 3 - Jun 2011
Volume 23, Issue 2 - Apr 2011
Volume 23, Issue 1 - Feb 2011
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Failure Characteristics of Oil Boom Considering the Nonlinear Interaction of Oil Boom with Waves
Cho, Yong-Jun ; Yoon, Dae-Kyung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 193~204
DOI : 10.9765/KSCOE.2011.23.3.193
To develop more robust oil boom which is vulnerable to various failure mode under severe weather condition, highly accurate wave model is developed using Spatially filtered Navier-Stokes Eq., LDS (Lagrangian Dynamic Smagorinsky model) for residual stresses, SPH (Smoothed Particle Hydrodynamics). To clarify the hydraulic characteristics of floating type oil boom, we numerically simulate the behavior of oil spill around oil boom under very energetic progressive waves. At the first stage, we firmly anchored the oil boom, and then, allowed the excursion of the oil boom. It turns out that oil boom with skirt of enough length (longer than 30% of depth) effectively confines the oil spill even against very energetic waves. We can also observe obliquely descending vertical eddies between y = 1~2 m as horizontal vortices shedding at the interface of oil spill and water are diffused toward the bottom, which is believed to be the birth, growing and break-down of Kelvin-Helmholz wave.
Precise Tidal Simulation on the Yellow Sea and Extended to North Western Pacific Sea
Suh, Seung-Won ; Kim, Hyeon-Jeong ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 205~214
DOI : 10.9765/KSCOE.2011.23.3.205
Finite element grid refinements with different intensities having 14 K, 52 K and 211 K on the Yellow Sea (YS) have been constructed to make precise tidal simulations. In the meanwhile 57 K grid was made to the extended North Western Pacific (NWP) sea. Numerical simulation were done based on 32 parallel processors by using pADCIRC v 49.21 model. In the YS tidal simulation on YS-G52K and YS-G211K grid structure, KorBathy30s and ETOPO1 bathymetry data are used and 4 major tidal constituents are prescribed from FES2004. Computed results are in good agreement within 0.138 meter in RMS error for amplification and 14.80 degree of phase compared to observed tidal records. Similar error bounds are acquired in the extended NWP tidal simulation on NWP-G57K grid with 8 tidal constituent prescription on the open boundary.
Time-dependent Performance-based Design of Caisson Breakwater Considering Climate Change Impacts
Suh, Kyung-Duck ; Kim, Seung-Woo ; Mori, Nobuhito ; Mase, Hajime ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 215~225
DOI : 10.9765/KSCOE.2011.23.3.215
During the past decade, the performance-based design method of caisson breakwaters has been developed, which allows a certain damage while maintaining the function of the structure. However, the existing method does not consider the changing coastal environment due to climate change impacts so that the stability of the structure is not guaranteed over the lifetime of the structure. In this paper, a time-dependent performance-based design method is developed, which is able to estimate the expected sliding distance and the probability of failure of a caisson breakwater considering the influence of sea level rise and wave height increase due to climate change. Especially, time-dependent probability of failure is calculated by considering the sea level rise and wave height increase as a function of time. The developed method was applied to the East Breakwater of the Hitachinaka Port which is located on the east coast of Japan. It was shown that the influence of wave height increase is much greater than that of sea level rise, because the magnitude of sea level rise is negligibly small compared with the water depth at the breakwater site. Moreover, investigation was made for the change of caisson width due to climate change impacts, which is the main concern of harbor engineers. The longer the structure lifetime, the greater was the increase of caisson width. The required increase of caisson width of the Hitachinaka breakwater whose width is 22 m at present was about 0.5 m and 1.5 m respectively for parabolic and linear wave height increase due to climate change.
Downtime Analysis for Pohang New Harbor through Long-term Investigation of Waves and Winds
Jeong, Weon-Mu ; Ryu, Kyong-Ho ; Baek, Won-Dae ; Choi, Hyuk-Jin ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 226~235
DOI : 10.9765/KSCOE.2011.23.3.226
Field measurements of the winds and waves were carried out for one year at multiple locations inside and outside of the Pohang New Harbor in order to clarify the reason of downtimes frequently occurring at most of the harbor quays and to establish an efficient countermeasure. In addition, the downtime records of the quays and precipitation data provided by Korea Meteorological Agency were acquired for mutual comparison and comprehensive analysis of the cause of downtimes. Except the influence of precipitation, it was found that the downtimes occurred when the height of waves entering into the harbor incurred by either one of swell, wind seas, or mixture of both, exceeded a threshold. The seiche whose period ranges from 5 to 80 minutes, which was suspected as a possible cause of the downtimes, is shown to have no direct relation with the downtimes. Meanwhile, the height of far-infra-gravity waves whose period ranges between 0.5 and 3 minutes, propagating to the harbor mouth forced by short period waves, showed almost proportional relationship with the height of short period waves. Based on the result of this study, it is concluded that the downtime problems of Pohang New Harbor can be greatly improved by effectively preventing the entrance of short period waves such as swell or wind seas.
Sea Level Rise due to Global Warming in the Northwestern Pacific and Seas around the Korean Peninsula
Oh, Sang-Myeong ; Kwon, Seok-Jae ; Moon, Il-Ju ; Lee, Eun-Il ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 236~247
DOI : 10.9765/KSCOE.2011.23.3.236
This study investigates sea level (SL) rise due to global warming in the Northwestern Pacific (NWP) and Seas around the Korean peninsula (KP) using outputs of IPCC AR4 climate models. Particularly, components of the SL rise induced by a local steric effect, which was not considered in most climate models, were computed using model-projected 3-dimensional temperature and salinity data. Analysis of the SL data shows that the ratio of the SL rise in the NWP and KP was about two times higher than that in global mean and particularly the ratio in the Kuroshio extension region was the highest. The SL rises over 100 years estimated from MPI_ECHAM5 and GFDL_CM2.1 model by A1B scenario considering the thermosteric effect were 24 cm and 28 cm for the NWP and 27 cm and 31 cm for the Seas around the KP, respectively. Statistical analysis reveals that these SL rises are caused by the weakening of the Siberian High in winter as well as variations of pressure system in the NWP and by the resultant change of water temperature. It also found that the highest SL rise in the Kuroshio extension region of the NWP was connected with the large increase of water temperature in this area.
A Study on Wave Responses of Vertical Tension-Leg Circular Floating Bodies
Lee, Kwang-Ho ; Kim, Chang-Hoon ; Kim, Do-Sam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 248~257
DOI : 10.9765/KSCOE.2011.23.3.248
In the present study, we proposed a new numerical wave tank model to analyze the vertical tension-leg circular floating bodies, using a 2-D Navier-Stokes solver. An IBM(Immersed Boundary Method) capable of handling interactions between waves and moving structures with complex geometry on a standard regular Cartesian grid system is coupled to the VOF(Volume of Fluid) method for tracking the free surface. Present numerical results for the motions of the floating body were compared with existing experimental data as well as numerical results based on FAVOR(Fractional Area Volume Obstacle Representation) algorithm. For detailed examinations of the present model, the additional hydraulic experiments for floating motions and free surface transformations were conducted. Further, the versatility of the proposed numerical model was verified via the numerical and physical experiments for the general rectangular floating bodies. Numerical results were compared with experiments and good agreement was archived.
Uncertainty Analysis of Wave Forces on Upright Sections of Composite Breakwaters
Lee, Cheol-Eung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 23, issue 3, 2011, Pages 258~264
DOI : 10.9765/KSCOE.2011.23.3.258
A MCS technique is represented to stochastically analyze the uncertainties of wave forces exerted on the upright sections of composite breakwaters. A stochastical models for horizontal and uplift wave forces can be straightforwardly formulated as a function of the probabilistic characteristics of maximum wave height. Under the assumption of wave forces followed by extreme distribution, the behaviors of relative wave forces to Goda's wave forces are studied by the MCS technique. Double-truncated normal distribution is applied to take the effects of uncertainties of scale and shape parameters of extreme distribution into account properly. Averages and variances of relative wave forces are quantitatively calculated with respect to the exceedance probabilities of maximum design wave height. It is found that the averages of relative wave forces may be decreased consistently with the increases of the exceedance probabilities. In particular, the averages on uplift wave force are evaluated slightly larger than those on horizontal wave force, but the variations of coefficient of the former are adversely smaller than those of the latter. It means that the uncertainties of uplift wave forces are smaller than those of horizontal wave forces in the same condition of the exceedance probabilities. Therefore, the present results could be useful to the reliability based-design method that require the statistical properties about the uncertainties of wave forces.