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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 27, Issue 6 - Dec 2015
Volume 27, Issue 5 - Oct 2015
Volume 27, Issue 4 - Aug 2015
Volume 27, Issue 3 - Jun 2015
Volume 27, Issue 2 - Apr 2015
Volume 27, Issue 1 - Feb 2015
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The Effect of the Volume of the Cellular Bulkhead on the Yield Load
Jang, Jeong-Wook ; Kim, Hyun-Guk ; Lee, Jae-Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 197~201
DOI : 10.9765/KSCOE.2015.27.4.197
Experimental and numerical analysis has been carried out in this paper to understand correlation between volume and yield of cellular bulkhead. It was firstly confirmed from these results that the conditions and parameters considered in the finite element analysis were reasonable and realistic due to the fact that the yield loads determined by the two different methods were equivalent in actual. Based on this results, a series of intensive numerical analysis has been further performed and revealed that the yield load varied in direct proportion to the change in the volume of the cellular bulkhead.
Solitary Wave-like Ship Induced Waves and Its Associated Currents in a Water Channel of Narrow Width
Cho, Yong Jun ; Choi, Han Rim ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 202~216
DOI : 10.9765/KSCOE.2015.27.4.202
In the narrow water channel, which has been frequently deployed in the artificial canal in the South Korea due to the lack of available land, solitary wave type ship induced waves can occur. In order to test this hypothetical view, we carried out the numerical simulation. Numerical model consists of Navier-Stokes Equations and VOF, and the verification is implemented using the data by PIANC (1987) and the analytical model derived in this study. It was shown that numerically simulated front wave height are much larger than the one by PIANC (1987), and the fluctuation of free surface near the channel bank persists much longer (around 20s). For the case of stern waves, numerically simulated wave height are somewhat smaller than the data by PIANC (1987). These results seriously deviates from the general characteristics of ship induced waves observed in the wide water channels, and leads us to conclude that ship induced waves is severely affected by the width of water channel. It was also shown that the currents from the channel banks toward a ship, and currents from the ship toward the channel banks are alternatively occurring due to reflection at the channel banks. The velocity of currents reaches its maximum at 0.90 m/s, and these values are sustained through the entire depth. which implies that severe scourings at the channel bottom can be underway.
Comparison of the Formulas for the Wave Forces Acting on the Perforated Caisson Breakwater
Ji, Chang-Hwan ; Oh, Sang-Ho ; Oh, Young-Min ; Lee, Dal Soo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 217~227
DOI : 10.9765/KSCOE.2015.27.4.217
In this study, two-dimensional physical experiment was carried out to examine the applicability of the three formulas(Takahashi and Shimosako, 1994; Tabet-Aoul and Lambert, 2003; Li, 2007), which were proposed to calculate the wave forces acting on perforated caisson breakwaters. In order to quantitatively compare the measured with the estimated values based on the wave formulas, the refined index of agreement and the coefficient of determination were calculated, by which the degree of agreement was evaluated. Among the three wave formulas, DUT formula (Li, 2007) showed the smallest deviation from the measured forces, whereas Takahashi formula (Takahashi and Shimosako, 1994) showed the largest deviation. Meanwhile, comparison of the magnitude of the measured wave forces with those from the three formulas revealed that DUT formula slightly underestimate, while the others overestimate the measured forces.
Field Observations of Spatial Structure of Hydrodynamics Including Waves and Currents in the Haeundae Coast
Do, Kideok ; Yoo, Jeseon ; Lee, Hee Jun ; Do, Jong-Dae ; Jin, Jae-Youll ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 228~237
DOI : 10.9765/KSCOE.2015.27.4.228
Field observations were conducted to collect hydrodynamic and morphological data, which are needed to account for mechanisms of bathymetry changes caused by physical forcings, in Haeundae beach. In order to quantitatively describe characteristics of wave transformations and current patterns in space in winter and summer, in-situ sensors for measuring waves and current profiles were installed at three locations in the cross-shore direction and also three locations in the along-shore direction. As for the results of wave measurements, waves with main direction from the east dominate in winter while waves are incident from the S and the ESE in summer. Analysis of current data reveals that currents over the study domain are considerably influenced by a pattern of tidal motions, thereby, mainly oscillating in the direction of tidal currents, i.e., east-west directions, in both winter and summer. Currents tend to be influenced by local bathymetry in the shallow water region, with the direction changed along the depth contours and the magnitude reduced as they approach the shoreline. The results analysed from the hydrodynamic data through this study can be further combined with the morphological and bathymetry data, leading to the quantification of seasonal sediment transport rates and sand budget changes.
Numerical Simulations of Rip Currents Under Phase-Resolved Directional Random Wave Conditions
Choi, Junwoo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 238~245
DOI : 10.9765/KSCOE.2015.27.4.238
Recently, Choi et al.(2015) showed that a numerical simulation of the SandyDuck experiment under a directional random wave environment agreed well with the experimental data including the wave height distribution of the random waves, the well-developed longshore current and its energetic fluctuation. Based on the Boussinesq modeling, this study investigates the effect of the alongshore variations, which are induced by not only the field topography but also the phase interaction of multidirectional random waves in the surf zone wave field, on the rip currents. As a result, transient rip currents as well as topographical rip currents cause the complicated surfzone circulation and mixing process due to their interactions in a multi-directional random wave condition while the topographical rip currents are dominant in a monochromatic wave condition.
Estimation of Time-dependent Damage Paths of Armors of Rubble-mound Breakwaters using Stochastic Processes
Lee, Cheol-Eung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 246~257
DOI : 10.9765/KSCOE.2015.27.4.246
The progressive degradation paths of structures have quantitatively been tracked by using stochastic processes, such as Wiener process, gamma process and compound Poisson process, in order to consider both the sampling uncertainty due to the usual lack of damage data and the temporal uncertainty associated with the deterioration evolution. Several important features of stochastic processes which should carefully be considered in application of the stochastic processes to practical problems have been figured out through assessing cumulative damage and lifetime distribution as a function of time. Especially, the Wiener process and the gamma process have straightforwardly been applied to armors of rubble-mound breakwaters by the aid of a sample path method based on Melby`s formula which can estimate cumulative damage levels of armors over time. The sample path method have been developed to calibrate the related-parameters required in the stochastic modelling of armors of rubble-mound breakwaters. From the analyses, it is found that cumulative damage levels of armors have surely been saturated with time. Also, the exponent of power law in time, that plays a significant role in predicting the cumulative damage levels over time, can easily be determined, which makes the stochastic models possible to track the cumulative damage levels of armors of rubble-mound breakwaters over time. Finally, failure probabilities with respect to various critical limits have been analyzed throughout its anticipated service life.
Occurrence Probability of Freak Waves at Nearshore of Donghae Harbor in the East Sea
Ahn, Kyungmo ; Oh, Chan Young ; Jeong, Weon Mu ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 258~265
DOI : 10.9765/KSCOE.2015.27.4.258
Over the last 20 years, freak waves have attracted many researchers because of their unexpected behaviors and damages on offshore structures and vessels in the ocean and coastal waters. Despite many researches on the causes, mechanisms and occurrence of freak waves, we have not reached consensus on the results of the researches. This paper presents the occurrence probability of freak waves based on the analysis of wave records measured at coastal waters of Donghae harbor in the East Sea. Three freak waves were found which satisfied conditions of m and
. The occurrence probabilities of freak waves were estimated from extreme distributions by Mori, Rayleigh and Ahn, and found to be on the orders of O(
), and O(
), respectively. The occurrence probabilities of freak waves measured from waves records were estimated between O(
) and O(
), which were located between predictions by Rayleigh and Ahn`s extreme probability distributions. However, we need more analysis of wave records obtained from diverse field conditions in order to verify the accuracy of the estimation of occurrence probability of freak waves.
Assessment of Offshore Wind Power Potential in the Western Seas of Korea
Ko, Dong Hui ; Jeong, Shin Taek ; Kang, Keum Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 266~273
DOI : 10.9765/KSCOE.2015.27.4.266
In this paper, annual wind data in 2014 at six locations(Seosudo, Gadaeam, Sibidongpa, Galmaeyeo, Haesuseo, Jigwido) are collected and analyzed in order to review optimal candidate site for offshore wind farm in the Western Seas of Korea. Observed wind data is fitted to Rayleigh and Weibull distribution and annual energy production is estimated according to wind frequency. GWE-3kH(3 kW-class) and GWE-10KU (10 kW-class) turbine are selected as wind turbine. Also, power curve are used to calculate wind energy potential. As a result, annual mean wind speed at six locations(Seosudo, Gadaeam, Sibidongpa, Galmaeyeo, Haesuseo, Jigwido) were calculated about 4.60, 4.5, 5.00, 5.13, 5.51, 5.90 m/s, respectively. In addition, annual energy production were estimated at 10,622.752, 11,313.05, 13,509.41, 14,899.55, 17,106.13, 19,660.85 kWh. Generally, annual mean energy density were between poor and marginal class and capacity factor at Jigwido was calculated at 22.44%. Its value is higher than the others.
Long-term Wave Monitoring and Analysis Off the Coast of Sokcho
Jeong, Weon Mu ; Ryu, Kyung-Ho ; Cho, Hongyeon ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 4, 2015, Pages 274~279
DOI : 10.9765/KSCOE.2015.27.4.274
Wave data acquired over eleven years near Sokcho Harbor located in the central area of the east coast were analyzed using spectral method and wave-by-wave analysis method and its major wave characteristics were examined. Significant wave heights were found to be high in winter and low in summer, and peak periods were also found to be long in winter and short in summer. The maximum significant wave height observed was 8.95 m caused by the East Sea twister. The distributional pattern of the significant wave heights and peak periods were both fitted better by Kernel distribution function than by Generalized Gamma distribution function and Generalized Extreme Value distribution function. The wave data were compiled to subdivide the wave height into intervals for each month, and the cumulative occurrence rates of wave heights were calculated to be utilized for the design and construction works in nearby construction works.