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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Ocean and Polar Research
Journal Basic Information
Journal DOI :
Korea Institute of Ocean Science & Technology
Editor in Chief :
Volume & Issues
Volume 25, Issue 4 - Dec 2003
Volume 25, Issue spc3 - Sep 2003
Volume 25, Issue 3 - Sep 2003
Volume 25, Issue 2 - Jun 2003
Volume 25, Issue 1 - Mar 2003
Selecting the target year
Prediction of Failure Probability of Breakwater using Neural Network
Kim, Dong-Hyawn ; Park, Woo-Sun ; Han, Sang-Hun ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 347~351
DOI : 10.4217/OPR.2003.25.spc3.347
A new approach to reliability analysis of rubble mound breakwater using neural network is proposed. At first, a neural network model which can estimate the stability number of any breakwaters for some design conditions is trained. Then, the neural network model is integrated with Monte Carlo simulation technique in order to calculate probability of failure for the breakwater. The proposed technique is compared with conventional approach using empirical formula.
Undrained Shear Strength of Marine Clays of Shihwa Region Obtained from CPTu
Jang, In-Sung ; Kim, Bum-Sang ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 353~360
DOI : 10.4217/OPR.2003.25.spc3.353
Estimation of undrained shear strength
of clayey soils from piezocone penetration test (CPTu), which has widely been known as one of very promising in situ test methods, requires piezocone factors. Empirical correlations are generally utilized to derive piezocone factors, but previous studies on the empirical piezocone factors are site-specific and in some cases need engineering characteristics, which should be obtained from additional laboratory tests. In this study, empirical cone factors were evaluated by comparing 6 CPTu results at Shihwa region in Korea with reference
values obtained from field vane test (FVT). From previous CPTu results of other regions in Korea as well as the results herein, the correlations between piezocone factor,
and CPTu results were investigated and three simplified evaluation methods of
using only CPTu results were presented. The
values estimated by
method shows better matches with those obtained from laboratory tests for marine clays at Shihwa region.
On the Wintertime Wind-driven Circulation in the Yellow Sea and the East China Sea : Part I. Effect of Tide-induced Bottom Friction
Lee, Jong-Chan ; Kim, Chang-Shik ; Jung, Kyung-Tae ; Jun, Ki-Cheon ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 361~371
DOI : 10.4217/OPR.2003.25.spc3.361
The effect of bottom friction on the steady wind-driven circulation in the Yellow Sea and the East China Sea (YSECS) has been studied using a two-dimensional numerical model with and without tidal forcing. Upwind flow experiment in YSECS has also been carried out with a schematic time variation in the wind field. The surface water setup and circulation pattern due to steady wind forcing are found to be very sensitive to the bottom friction. When the effects of tidal currents are neglected, the overall current velocities are overestimated and eddies of various sizes appear, upwind flow is formed within the deep trough of the Yellow Sea, forming a part of the topographic gyre on the side of Korea. When tidal forcing is taken into account, the wind-induced surface elevations are smoothed out due to the strong tide-induced bottom friction, which is aligned almost normal to the wind stresses; weak upwind flow is farmed in the deep trough of the Yellow Sea, west and south of Jeju. Calculation with wind forcing only through a parameterized linear bottom friction produces almost same results from the calculation with
tidal forcing and wind forcing using a quadratic bottom friction, supporting Hunter (1975)'s linearization of bottom friction which includes the effect of tidal current, can be applied to the simulation of wind-driven circulation in YSECS. The results show that steady wind forcing is not a dominant factor to the winter-time upwind flow in YSECS. Upwind flow experiment which considers the relaxation of pressure gradient (Huesh et al. 1986) shows that 1) a downwind flow is dominant over the whole YSECS when the northerly wind reaches a maximum speed; 2) a trend of upwind flow near the trough is found during relaxation when the wind abates; 3) a northward flow dominates over the YSECS after the wind stops. The results also show that the upwind flow in the trough of Yellow Sea is forced by a wind-induced longitudinal surface elevation gradient.
Drivability of Offshore Pile Foundation at Ieodo Ocean Research Station
Shim, Jae-Seol ; Yoon, Gil-Lim ; Lee, Seung-Jun ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 373~384
DOI : 10.4217/OPR.2003.25.spc3.373
When pile foundation is constructed by dynamic method, it is desirable to perform monitoring of drivability with pile penetration. Dynamic pile monitoring yields information regarding driving hammer, cushion, pile and soil behaviour that can be used to confirm the assumptions of wave equation analysis. In this study, dynamic monitoring of the steel pipe pile was performed with Pile Driving Analyser (PDA). The PDA utilizes the wave propagation theory to compute numerous variables which describe the conditions of the hammer-pile-soil system in real-time and following each hammer impact. This approach allows immediate field verification of hammer performance, driving efficiency, and estimation of pile bearing capacity. A series of PDA test were performed at the Ieodo Ocean Research Station (IORS) located in southeast of Marado, a southernmost small island south of Jeju Island. The drilling core sediments of Ieodo subsoil are composed of mud and sand, showing lamination and wavy or lenticular bedding, which were often bioturbated. This paper summarizes the results of PDA tests which were applied in measurement and estimation of large diameter open ended steel pipe pile driven by steam hammer, Vulcan-560 and MRBS-4600, at the marine sediments.
Experimental Evaluation of Construction Performance and Long-term Settlements in Soft Ground Breakwater
Kwon, O-Soon ; Jang, In-Sung ; Park, Woo-Sun ; Yum, Ki-Dai ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 385~392
DOI : 10.4217/OPR.2003.25.spc3.385
A new type of soft ground breakwater was recently developed, which does not need ground improvement because of light weight and structural characteristics. The various studies about consolidation settlements and lateral behavior of proposed soft ground breakwater have been conducted. But, the systematic investigations on the construction performance and long-term settlements of new type breakwater has not been accomplished. In this study, construction simulation of soft ground breakwater with soil box model test and experiments of the long-term wave loaded breakwater were performed. The results of test shows that it is possible to compensate differential settlements by dead loading and/or suction pressure, and to reduce the consolidation settlements by preloading method. It was also found that the vertical and lateral displacements of long-term wave loaded breakwater were negligible.
Comparison of the Net Inflow Rates of Seawater Exchange Breakwater of Different Shapes
Lee, Dal-Soo ; Lee, Chang-Hoon ; Oh, Young-Min ; Chun, In-Sik ; Kim, Chang-Il ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 393~397
DOI : 10.4217/OPR.2003.25.spc3.393
The seawater exchange breakwaters can be effectively employed to conserve or enhance the water quality inside harbors by transmitting the exterior water into the harbor. In the present study, three shapes of the breakwater, that is, the flow conduit embedded type, the wave chamber type and the oscillating water channel type are compared far their water exchanging capability through regular wave experiments. The results show that the net influx of water appears differently depending on wave period for each breakwater type. The net influx of the wave chamber type is much greater than that of the flow conduit embedded type. It is also ascertained that the influx of the oscillating water channel type can be greatly enhanced by attaining the resonance condition inside the channel at the wave periods frequently occurring at the fields where the breakwaters are to be installed.
Behavior of Currents and Suspended Sediments around a Silt Screen
Jin, Jae-Youll ; Chae, Jang-Won ; Song, Won-Oh ; Park, Jin-Soon ; Kim, Sung-Eun ; Jeong, Weon-Mu ; Yum, Ki-Dai ; Oh, Jae-Kyung ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 399~408
DOI : 10.4217/OPR.2003.25.spc3.399
The behavior of Suspended Sediment Concentrations (SSC) around a silt screen in a microtidal coastal area was hydrodynamically measured. The current speed at the mid-layer about 30m downstream of the screen reduces to about half that at the same distance upstream. It was caused by the contraction of the vertical section due to the screen. Even during a relatively weak storm period the SSC increases to that of the value caused by dredging. Section-averaged SSC at the downstream of the screen is higher by about 60% than that at the upstream, suggesting that the silt screen plays an adverse effect rather than a constructive role in the reduction of SSC generated by dredging.
A Review of Measures against Environmental Impact of Suspended Sediments Generated by Coastal Development Works
Song, Won-Oh ; Jin, Jae-Youll ; Chae, Jang-Won ; Ahn, Hee-Do ; Maeng, Jun-Ho ; Oh, Jae-Kyung ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 409~416
DOI : 10.4217/OPR.2003.25.spc3.409
Coastal development works generally increase the suspended sediment concentration of the ambient water, causing environmental impacts in various manners. The most active measures in three sides have been reviewed for their applicabilities in Korea. Referring to the cases in the USA, the legislation of environmental windows seems to be not proper for Environmentally Sound and Sustainable Developments (ESSD) until sufficient scientific data are obtained to address the individual issues of potential negative impacts. Feedback monitoring can be regarded as the best way for ESSD. Korea also has the basic legal system for the feedback monitoring as well as Environmental Impact Assessments (EIA). However, the frequency, period and parameter of related surveys should be improved for the true ESSD. Moreover, environmental facilities such as environmental dredgers should be widely used for mitigating environmental Impacts caused by coastal development works.
Comparison of Calculation Methods of Cumulative Damage of Breakwater Armor Layer
Suh, Kyung-Duck ; Chang, Eun-Seok ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 417~421
DOI : 10.4217/OPR.2003.25.spc3.417
In the reliability design of the breakwater armor layer, it is often necessary to calculate its damage accumulated over the life of the breakwater. In this paper comparison is made between the two methods proposed by Hanzawa et at. in 1996 and Melby and Kobayashi in 1998 to calculate the cumulative damage of the breakwater armor layer. Tn the case where a severe damage occurs at the beginning of the life or toe breakwater, the two methods do not show significant difference, but in general the farmer predicts a cumulative damage several times larger than the latter.
Effects of the Oscillating Water Channel Length on the Water Surface Elevation within Seawater Exchange Breakwater
Lee, Dal-Soo ; Oh, Young-Min ; Chun, In-Sik ; Kim, Chang-Il ;
Ocean and Polar Research, volume 25, issue spc3, 2003, Pages 423~426
DOI : 10.4217/OPR.2003.25.spc3.423
The seawater exchange breakwater equipped with an oscillating water channel and water transmitting pipes has a very spectacular function that seawater supply can be greatly increased due to the upsurge of the water surface inside the channel at resonance condition which can be reached when the incident wave period becomes close to the natural period of the channel. The variations of the water level and period inside the channel are very important factors in enhancing the efficiency of sea water exchange, especially when designing the breakwater cross-section in shallow water zone which requires longer resonance period with the elongated horizontal projection of the channel. In the present study, a hydraulic experiment was performed varying the length of the oscillating channel, and the resonance periods and water surface variations are analyzed in terms of water transmission through the pipes.