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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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
Selecting the target year
Effect of Model Resolution on The Flow Structures Near Mesoscale Eddies
Chang, Yeon S. ; Ahn, Kyungmo ; Park, Young-Gyu ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 79~93
DOI : 10.9765/KSCOE.2015.27.2.79
Three-dimensional structures of large ocean rings in the Gulf Stream region are investigated using the HYbrid Coordinate Ocean Model (HYCOM). Numerically simulated flow structures around four selected cyclonic and anticyclonic rings are compared with two different horizontal resolutions:
. The vertical distributions of Lagrangian Coherent Structures (LCSs) are analyzed using Finite Size Lyapunov Exponent (FSLE) and Okubo-Weiss parameters (OW). Curtain-shaped FSLE ridges are found in all four rings with extensions of surface ridges throughout the water columns, indicating that horizontal stirring is dominant over vertical motions. Near the high-resolution rings, many small-scale flow structures with size O(1~10) km are observed while these features are rarely found near the low-resolution rings. These small-scale structures affect the flow pattern around the rings as flow particles move more randomly in the high-resolution models. The dispersion rates are also affected by these small-scale structures as the relative horizontal dispersion coefficients are larger for the high-resolution models. The absolute vertical dispersion rates are, however, lower for the high-resolution models, because the particles tend to move along inclined eddy orbits when the resolution is low and this increases the magnitude of absolute vertical dispersion. Since relative vertical dispersion can reduce this effect from the orbital trajectories of particles, it gives a more reasonable magnitude range than absolute dispersion, and so is recommended in estimating vertical dispersion rates.
A Study on Trend Analysis in Sea Level Data Through MK Test and Quantile Regression Analysis
Uranchimeg, Sumiya ; Kim, Yong-Tak ; Kwon, Hyun-Han ; Hwang, Kyu-Nam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 94~104
DOI : 10.9765/KSCOE.2015.27.2.94
Population and urban development along the coast is growing in South Korea, and particularly sea level rise is likely to increase the vulnerability of coastal areas. This study aims to investigate the sea level rise through Mann-Kendall(MK) test, ordinary linear regression(OR) and quantile regression analysis(QRA) with sea level data at the 20 tide stations along the coast of Korean Peninsula. First, statistically significant long-term trends were analysed using a non-parametric MK test and the test indicated statistically significant trends for 18 and 10 stations at the 5% significance level in the annual mean value of sea level and the annual maximum value of sea level, respectively. The QRA method showed better performance in terms of characterizing the degree of trend. QRA showed that an average annual rise in mean sea level is about 1-6 mm/year, and an average rise in maximum sea level is about 1-20 mm. It was found that upward convergent and upward divergent were a representative change given the nine-category distributional changes. We expect that in future work we will address nonstationarities with respect to sea level that were identified above, and develop a nonstationary frequency analysis with climate change scenarios.
A Laboratory Study on Erosional Properties of the Deposit Bed of Saemankeum Sediments
Yang, Su-Hyun ; Lee, Seung-Jong ; Hwang, Kyu-Nam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 105~112
DOI : 10.9765/KSCOE.2015.27.2.105
In this study, the erosional properties of deposit bed for the natural sediments are quantitatively estimated domestically for the first time using annular flume. Four erosion tests for Saemankeum sediments have been carried out on different consolidation time. Experimental results of erosional tests show that shear strength
increases with the increases of consolidation time and bed depth. The erosion rate increases logarithmically with the increases of exceed shear strength
. But, the erosion rate decreases rapidly with the decreases of exceed shear strength under the
. Experimental results of this study are found to be remarkably different in quantity as compared with those for results of previous study.
Three-Dimensional Flow Response Analysis of Subsea Riser Transporting Deep Ocean Water
Hwang, Hajung ; Woo, Jinho ; Na, Won-Bae ; Kim, Hyeon-Ju ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 113~117
DOI : 10.9765/KSCOE.2015.27.2.113
This study presents a 3-dimensional flow-structure interaction analysis of subsea risers in water flows. Two structural connectors (flat and circular couplers) were intentionally devised and numerically tested using ANSYS CFX to investigate how these couplers behave under the water flows. In the flow analysis, the water field was constructed with an inlet, outlet, and symmetric boundary conditions. As a result, the responses (drag coefficients and pressure fields) were obtained and the pressure fields were applied for the structural analysis. Finally, the structural responses (displacements and equivalent stresses) of the risers were measured to demonstrate the efficiency of the riser connectors.
An Analytical Solution of Dynamic Responses for Seabed under Flow and Standing Wave Coexisting Fields
Lee, Kwang-Ho ; Kim, Dong-Wook ; Kim, Do-Sam ; Kim, Tae-Hyung ; Kim, Kyu-Han ; Jeon, Jong-Hyeok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 118~134
DOI : 10.9765/KSCOE.2015.27.2.118
An analytical solution of dynamic responses for seabed in shallow, finite and infinite thicknesses has been developed under flow and standing wave coexisting field at a constant water depth condition. To do this, based on the Biot`s consolidation theory, the seabed is assumed as a porous elastic media with the assumptions that pore fluid is compressible and Darcy law governs the flow. The developed analytical solution is compared with the previous results and is verified. Using the analytical solution the deformation, pore pressure, effective and shear stresses of seabed are examined under various given values of flow velocity, incident wave period and seabed thickness. From this study, it is confirmed that the seabed response is quite different depending on consideration of flow, which causes changing period and length of incident and reflection waves.
Comparison of Stability Coefficients of Radial Shape Armor Blocks Depending on Placement Methods
Min, Eun-Jong ; Cheon, Se-Hyeon ; Suh, Kyung-Duck ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 135~141
DOI : 10.9765/KSCOE.2015.27.2.135
In this study, two different uniform placement methods are proposed for each of Tetrapod, Rakuna-IV, and Dimple armoring a rubble mound breakwater, and the corresponding stability coefficients are determined by hydraulic experiments. The Tetrapod and Rakuna-IV show similar stability coefficients regardless of the placement methods, whereas the Dimple shows somewhat different stability coefficients depending on the placement methods. It is shown that the Dimple gives the largest stability coefficient, whereas the Tatrapod gives the smallest value. The uniform placement methods of Tatrapod and Rakuna-IV give slightly larger stability coefficients than the random placement, whereas the uniform placements of Dimple give much larger stability coefficients than the random placement. However, the small void ratio of uniform placements of Dimple requires attention because the blocks would behave like single layer system blocks so that brittle failure could occur.
Analysis of the Long-term Wave Characteristics off the Coast of Daejin
Jeong, Weon Mu ; Cho, Hongyeon ; Baek, Wondae ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 27, issue 2, 2015, Pages 142~147
DOI : 10.9765/KSCOE.2015.27.2.142
Wave data acquired over seven years near Daejin Harbor located in the north central area of the east coast was 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 6.59 m and was caused by Typhoon No. 1216, SANBA. The distributional pattern of the significant wave heights and peak periods were both reproduced better by Kernel distribution function than by Generalized Gamma distribution function and Generalized Extreme Value distribution function. Meanwhile, the wave data was subdivided by month and wave height level and the cumulative appearance rate was proposed to aid designing and constructing works in nearby coastal areas.