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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 21, Issue 6 - Dec 2009
Volume 21, Issue 5 - Oct 2009
Volume 21, Issue 4 - Aug 2009
Volume 21, Issue 3 - Jun 2009
Volume 21, Issue 2 - Apr 2009
Volume 21, Issue 1 - Feb 2009
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Evaluation of Partial Safety Factors on Sliding of Monolithic Vertical Caisson of Composite Breakwaters
Lee, Cheol-Eung ; Park, Dong-Heon ; Kwon, Hyuk-Jae ; Lee, Sun-Yong ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 267~277
Partial safety factors of the load, resistance, and reliability function are evaluated according to the target probability of failure on sliding mode of monolithical vertical caisson of composite breakwaters. After reliability function is formulated for sliding failure mode of caisson of composite breakwaters regarding bias of wave force, uncertainties of random variables related to loads, strengths are analyzed. Reliability analysis for the various conditions of water depth, geometric, and wave conditions is performed using Level II AFDA model for the sliding failure. Furthermore, the reliability model is also applied to the real caisson of composite breakwaters of Daesan, Dong- hae, and Pohang harbor. By comparing the required width of caisson of composite breakwater according to target probability of failure with the other results, the partial safety factors evaluated in this study are calibrated straightforwardly. Even though showing a little difference on the 1% of target probability, it may be found that the present results agree well with the other results in every other target probability of failure.
Reliability Analysis and Evaluation of Partial Safety Factors for Sliding of Caisson Breakwaters in Korea
Kim, Seung-Woo ; Suh, Kyung-Duck ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 278~289
In the present study, we evaluated the target reliability indices and partial safety factors for caisson sliding of a vertical breakwater. The average of the reliability indices of existing breakwaters was proposed as the target reliability index for the breakwater of normal safety level. The target reliability indices of high and low safety levels were also proposed based on the analysis of breakwaters in Korea and Japan. The partial safety factors were then proposed for each safety level by averaging the values calculated for 12 breakwater crosssections in Korea. The appropriateness of the proposed partial safety factors was partly verified by showing that the reliability index calculated by using the present partial safety factors is located between those of mild and steep bottom slopes of JPHA(2007). The proposed partial safety factors were inversely used to calculate the caisson width and reliability index of existing breakwaters. While the reliability indices of existing breakwaters designed by the deterministic method show a large variation, those designed by the partial safety factor method show a small variation. This indicates that the partial safety factor method allows a consistent design for given target probability of failure.
A Quasi-nonlinear Numerical Analysis Considering the Variable Membrane Tension of Vertical Membrane Breakwaters
Chun, In-Suk ; Kim, Sun-Sin ; Park, Hyun-Ju ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 290~300
The existing numerical methods on the vertical membrane breakwater have employed a linear analysis where the variable membrane tension occurring during membrane motions is assumed to be very negligible compared to the initial tension. In the present study, a quasi-nonlinear analysis is attempted such that the temporary tension of the membrane is substituted by the average tension for a wave period that is sought by an iterative calculation. The results showed that with the increase of the wave period the reflection coefficients appeared larger and the transmission coefficients smaller compared to the results of the linear analysis. The application of the quasi-nonlinear analysis also showed that the performance of the structure is closely dependent on the horizontal deformation of the membrane. In order to suppress the horizontal deformation, it may be required to take the larger initial tension of the membrane or to put additional mooring lines in the middle of the vertical faces of the membrane. But for theses methods to be effective, a largely sized surface float should be installed to secure enough buoyancy to support such downward forces.
Analysis of Helical Turbine Characteristics for Tidal Current Power Plant
Han, Sang-Hun ; Lee, Kwang-Soo ; Yum, Ki-Dae ; Park, Woo-Sun ; Park, Jin-Soon ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 301~307
The Korean peninsula has a number of coastal sites where the rhythmic rising and lowering of water surface due to tides results in strong tidal current. The kinetic energy of these currents can be efficiently exploited by use of tidal current turbines. This paper investigates the characteristics of helical turbine based on in-field test. The experimental frame was constructed at the Uldolmok narrow channel between Jindo and Haenam and installed the helical turbine of diameter 2.2 m and height 2.5 m. 3-blade turbine had the maximum efficiencies of about 30% in the current velocity range between 1.5 and 2.3 m/s and 6-blade turbine han the maximum efficiencies of about 25%. The efficiency was constant with the current velocity. TSRs of 3-blade and 6 blade turbines were observed as 2.4 and 1.9 respectively.
Design Wave Transformation in Finite Depth due to Wave-Current Interaction
Kang, See-Whan ; Ahn, Suk-Jin ; Eom, Hyun-Min ; Cho, Hyu-Sang ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 308~315
Wave-current interaction due to strong ambient currents causes to alter wave properties such as wave height, wave profile and wave spectrum. In this study we first examined the SWAN model's applicability by comparing with an analytical solution of Suh et al. (1994) for wave-current interaction in finite water-depth. Numerical experiments using SWAN model have been conducted for Garolim Bay to estimate the design waveheights influenced by strong tidal currents. For the design wave periods of 8~10 sec, the design wave height of 3 m in NNW direction was increased by up to 40% when the incident waves encounter the opposing currents of 1.4 m/s while the wave height was reduced by 26% due to the following currents of 1.1 m at the bay mouth. This result indicates that the effect of wave-current interaction must be included to determine the design wave height if there exists a strong current.
A Study of New Technical Standards for Slope Stability in Port Structures
Yoon, Gil-Lim ; Yoon, Yeo-Won ; Kim, Hong-Yeon ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 316~325
Technical design codes of slope stability for port structures were studied by comparing local Korean code with international codes; Japanese, EC and China codes. Three international design codes are based on limit state design method. Although Chinese code was based on the modified Fellenius method in slope stability analyses, it is currently changing to the simplified Bishop method. In Eurocode, the Morgenstern & Price method or the Bishop method is recommended. In Japanese code, however, the modified Fellenius method is preferentially recommended, but the simplified Bishop method could be alternatively used in case of thick sandy ground conditions. As for design parameter determination, Eurocode has stipulated comprehensive partial factors and partial material factors, however Japanese code has clarified empirical partial material factors for each port structure. Chinese code, the minimum ranges of the comprehensive partial factors are stipulated, and the use of the strength index by specific tests is concretely clarified with the safety condition. Case study of slope stability analyses showed the safety factors were higher in order of Chinese, Japanese and Eurocode, respectively.
Beach Erosion along the Northeast Texas Coast by Remote Storm
Park, Young-Hyun ; Edge, Billy L. ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 326~333
US coast along the Gulf of Mexico has been suffered damages every year by powerful hurricanes which were generated there. Waves and storm surges by hurricane are a factor of overwash to cause permanent damages, a highway along the Texas coast was closed and it is impossible to live there due to that reason. overwash is found as a main cause by analysis of short and long term field measurements. When we consider that few landfall of hurricane have been made in the study area, long period swells by gigantic hurricane cause overwash along the Northeast Texas coast.
Scattering of Obliquely Incident Waves by a Semi-infinite Breakwater or a Breakwater Gap of Partial Reflection
Kim, Han-Na ; Suh, Kyung-Duck ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 21, issue 4, 2009, Pages 334~344
In the present paper, analytic solutions are derived for scattering of obliquely incident waves by a semi-infinite breakwater or a breakwater gap of partial reflection. In order to examine the appropriateness of the derived solutions, they are compared with the solutions derived by McIver in 1999 and Bowen and McIver in 2002 for a semi-infinite breakwater and a breakwater gap, respectively, in the case of perfect reflection. The derived analytic solutions are used to investigate the effect of reflection coefficient of the breakwater and wave incident angle upon the tranquility at harbor entrance. The tranquility is deteriorated by the reflected waves as the reflection coefficient increases and as the waves are incident more obliquely.