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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 20, Issue 6 - Dec 2008
Volume 20, Issue 5 - Oct 2008
Volume 20, Issue 4 - Aug 2008
Volume 20, Issue 3 - Jun 2008
Volume 20, Issue 2 - Apr 2008
Volume 20, Issue 1 - Feb 2008
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Reliability Analysis of Multiple Failure Modes of Rubble-Mound Breakwaters
Lee, Cheol-Eung ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 137~147
A reliability analysis has been performed to investigate the systematic stability of multi-failure modes of rubble-mound breakwaters. The reliability functions of four different failure modes are established straightforwardly. AFDA(Approximate Full Distribution Approcah) reliability models for each failure modes are directly developed and satisfactorily calibrated through the comparison with CIAD's results. In the reliability analysis of single failure mode, the probabilities of failure are calculated and the influence coefficients of random variables in the failure modes are properly evaluated. Meanwhile, three different models such as uni-modal bounds, bimodal bounds, and PNET are applied to evaluate the probabilities of failure of multi-failure modes for rubble-mound breakwaters. It may be found that uni-modal bounds tend to overestimate the probability of failure of multi-failure modes. Therefore, for the systematic reliability analysis of multi-failure modes, it is recommended to use bi-modal bounds or PNET which consider the correlation between the failure modes for rubble-mound breakwaters. By introducing the reliability analysis of multi-failure modes, it could be possible to find out the additional probabilities of failure occurred by the multi-failure modes of a multi-component system such as rubble-mound breakwaters.
A Study on the Extension of WAM for Shallow Water
Chun, Je-Ho ; Ahn, Kyung-Mo ; Yoon, Jong-Tae ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 148~156
WAM(WAve Model), deep water wave model has been extended to the region of shallow water, incorporating wave breaking, and triad wave interaction. To verify this model, two numerical simulations for hydraulic experiments of Chawla et al.(1998) and Beji and Battjes(1993) are performed. The computed results show good agreements with measured ones. To identify its applicability to real sea, it is applied to storm wave modelling for typhoon Maemi. Numerical results compared with measured ones at Geoje, Busan and Ulsan show reasonable wave height estimations.
Experimental Study of Overtopping Void Ratio by Wave Breaking
Ryu, Yong-Uk ; Lee, Jong-In ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 157~167
The aeration of an overtopping wave on a vertical structure generated by a plunging wave was investigated through laboratory measurements of void fraction. The overtopping wave occurring after wave breaking becomes multi-phased and turbulent with significant aeration, so that the void fraction of the flow is of importance. In this study, fiber optic reflectometer and bubble image velocimetry were employed to measure the void fraction, velocity, and layer thickness of the overtopping flow. Mean properties were obtained by ensembleand time-averaging the repeated instantaneous void fractions and velocities. The mean void fractions show that the overtopping wave is very high-aerated near the overtopping wave front and relatively low-aerated near the deck surface and rear free surface of the wave. The flow rate and momentum of the overtopping flow estimated using the measured data show that the void ratio is an important parameter to consider in the multiphase flow. From the similarity profiles of the depth-averaged void fraction, velocity, and layer thickness, one-dimensional empirical equations were obtained and used to estimate the flow rate and momentum of the overtopping flow.
Estimation of Gate Discharge Capacity by Physical Model Test and FLOW-3D
Park, Byong-Jun ; Lee, Sang-Hwa ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 168~175
In this study, we estimated the discharge capacity of Solicheon sluice gate in Gunjang national industrial complex by hydraulic physical scale model test and FLOW-3D. It was showed that the discharge capacity of gate carried by physical model test and numerical analysis was similar.
Probabilistic Assessment of Wave Overtopping of Seawall at Busan, Korea
Qie, Luwen ; Choi, Byung-Ho ; Xie, ShiLeng ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 176~183
In this paper, three classical overtopping models: Owen model, Van der Meer & Janssen model and Hedges & Reis model were used to calculate the failure probability of wave overtopping of seawalls. Among of them, the Hedges & Reis model was regarded as a moderate method to analyze the failure probability of wave overtopping of seawalls and the probabilistic assessments of wave overtopping were carried out for a constructing seawall at Busan in Korea by Level II and Level III reliability methods. Considering the cost of construction, an appropriate crest level was proposed for a certain rate of wave overtopping at a lower failure probability.
Estimation of Hydraulic States Caused by Gate Expansion in Asan Bay
Park, Byong-Jun ; Lee, Sang-Hwa ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 184~193
The gate expansion was planed to increase discharge capacity of gate structure at sea dike in Asan Bay. So it was estimated for changing of hydraulic states in Pyeongteak Harbor Zone caused by gate expansion, using Delft3D, FLOW-3D and hydraulic physical scale model testing. In result, the influence of gate expansion was indicated to be weak.
Practical Construction of Tsunami Inundation Map to Link Disaster Forecast/Warning and Prevention Systems
Choi, Jun-Woo ; Kim, Kyung-Hee ; Jeon, Young-Joon ; Yoon, Sung-Bum ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 194~202
In general, forecast tsunami heights announced for tsunami warning are computed by using a linear tsunami model with coarse grids which leads the underestimation of inundation area. Thus, an accurate tsunami inundation map corresponding the forecast tsunami height is needed for an emergency evacuation plan. A practical way to construct a relatively accurate tsunami inundation map was proposed in this study for the quantitative forecast of inundation area. This procedure can be introduced as in the followings: The fault dislocations of potential tsunami sources generating a specific tsunami height near an interested area are found by using a linear tsunami model. Based on these fault dislocations, maximum inundation envelops of the interested area are computed and illustrated by using nonlinear inundation numerical model. In this study, the tsunami inundation map for Imwon area was constructed according to 11 potential tsunami sources, and the validity of this process was examined.
Pier-Scour Characteristics of the Marine Bridge with Ship Impact Protection - Incheon Bridge Case -
Yeo, Woon-Kwang ; Ji, Un ; Kim, Chang-Sung ; Lim, Jong-Chul ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 203~211
More recently, the massive marine bridges in a ship passage have been constructed on the sea. Therefore, the ship impact protection for the bridge-piers are installed to consider the possibility of vessel collision danger. Due to the ship impact protection, the pier-scour characteristics are changed in comparison with the condition without the ship impact protection (SIP). In this study, the physical modeling for the Incheon Sea-Crossing Bridge was performed to analyze the pier-scour characteristics with respect to the vessel collision protection. The rigid and movable bed tests were conducted to evaluate the flow pattern, scour depth, and scourhole with and without the ship impact protection. The experimental results for the maximum scour depth is increased 0.24 m in W1 pier at the same location and 2.4 m in W2+3+4 piers due to the SIP installation. Especially, the maximum scour depth in W2+3+4 piers was occurred around the SIP.
사다리형태로 변화하는 지형 위를 통과하는 파군에 의한 장파의 생성
Cho, Yong-Sik ; Lee, Jin-Woo ; Jung, Tae-Hwa ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 212~218
A possible source of resonant problems in a harbor is long waves generated by incident wave groups. The analytical solutions of the governing equations of second-order long waves derived using a multiple-scale perturbation method consist of the locked and free long waves. The locked long waves propagate at some group velocity, whereas the free long waves propagate at the shallow-water speed. To study the resonance of free long waves, a trapezoidally varying topography is employed. With certain combinations of incident angle, water depth, and ambient current velocity, free long waves can be trapped and resonated.
Estimation on the Regions of Freshwater Influence using the Seasonal Salinity Data in Asan Bay Coastal Zone
Cho, Hong-Yeon ; Cho, Beom-Jun ; Kim, Sang-Jun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 219~231
This study analyzes a general pattern of the gate operation at the Asan bay seadikes and its effects on salinity. The coefficient of determination between precipitation and released freshwater from gate operation turns out to be 0.77-0.89. A stratification is not shown in the analysis of the salinity in upper and lower layers at the Asan bay because of strong tidal effects, and the coefficient of determination between runoff and salinity is in the range of 0.49-0.62 except station Daesan 4. Salinity observations from 8 stations show mean and standard deviation are highly correlated (coefficient of determination=0.9936), and both mean and standard deviation are influenced by freshwater. Eventually it is found that stations Asan 2 to 4 and Daesan 1 are within the regions of the freshwater influences.
The Experimental Study on the Evaluation of Tidal Power Generation Output Using Water Tank
Jeong, Shin-Taek ; Kim, Jeong-Dae ; Ko, Dong-Hui ; Choi, Woo-Jung ; Oh, Nam-Sun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 232~237
A method to generate electric power from small scale water tank. For this purpose, manufacturing tank is investigated, measuring water level change at any time, and finally comparing experimental and theoretical value, are performed. Inner and outer tank are made to simulate flood and ebb generation. Two sets of pipe are connected between tanks, and experiments are performed under varying flowrate. Coefficients of flowrate are calculated comparing water level change data and theoretical value. Measured and theoretical water levels are highly correlated, and this ascertains that analytical equation simulates real water level changes well. Flowrate change depending on the existence of propeller and valve, on flood and ebb generation, shows the necessity of experiments in the process of manufacturing electric power system. Moreover, total energy calculated from experimental data agrees well with that of theoretical equation. In spite of small tidal power output, this generating system with optimum water tank can be applied to any place where high water level change occurs, and can make a contribution to producing new and renewable energy consequently.
Wave Reflection and Transmission from Buoyant Flap Typed Storm Surge Barriers - Hydraulic Experiments
Jeong, Shin-Taek ; Kim, Jeong-Dae ; Ko, Dong-Hui ; Kim, Dong-Hyawn ; Park, Woo-Sun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 2, 2008, Pages 238~245
To evaluate wave reflection and transmission from buoyant flap-typed storm surge barriers, hydraulic experiments were performed by using regular and irregular wave conditions. Buoyant flap-typed storm surge barriers consist of buoyant main body connected with foundation structure in the seabed by hinge. The characteristics of wave reflection, transmission and dynamic response of the structure were investigated for 36 regular and 4 irregular wave conditions. It was also evaluated the usage of plain plate attached on the buoyant main body as one of alternatives to control wave reflection and transmission. From the hydraulic experiments, it was found that the case of plain plate attached on the offshore side is very effective to improve the wave transmission as well as reflection. But, the effect of the case on the harbor side might be negligible.