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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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Estimation of Probability Density Function of Tidal Elevation Data using the Double Truncation Method
Jeong, Shin-Taek ; Cho, Hong-Yeon ; Kim, Jeong-Dae ; Hui, Ko-Dong ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 247~254
The double-peak normal distribution function (DPDF) suggested by Cho et al.(2004) has the problems that the extremely high and low tidal elevations are frequently generated in the Monte-Carlo simulation processes because the upper and lower limits of the DPDF are unbounded in spite of the excellent goodness-offit results. In this study, the modified DPDF is suggested by introducing the upper and lower value parameters and re-scale parameters in order to remove these problems. These new parameters of the DPDF are optimally estimated by the non-linear optimization problem solver using the Levenberg-Marquardt scheme. This modified DPDF can remove completely the unrealistically generated tidal levations and give a slightly better fit than the existing DRDF. Based on the DPDF's characteristic power, the over- and under estimation problems of the design factors are also automatically intercepted, too.
Numerical Simulation of Ship-induced Wave Using FLOW-
Kang, Young-Seung ; Kim, Pyeong-Joong ; Hyun, Sang-Kwon ; Sung, Ha-Keun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 255~267
Using the commercial CFD code FLOW-
which has an implicit General Moving Object (GMO) method, the ship-induced wave has been simulated. In the implicit GMO method of the FLOW-
, a rigid body's motion which is either user-prescribed (prescribed motion) or dynamically coupled to fluid flow (coupled motion) can be computed with six degrees of freedom (DOF). The simulated horizontal wave patterns are agree with the wave patterns represented by depth Froude number. The model has been well-simulated to generate the depth-dependent wave transformation in comparison of uniform depth case to complicated depth case. Additionally, it shows that ship-induced waves have been reasonably generated by two ships passing each other and by a ship moving in a curve. Therefore, it is suggested that the FLOW-
model calibrated with observed data should provide more accurate prediction for the ship-induced wave in a certain fairway or harbor.
Propagation Characteristics of Potential Tsunamis in Okinawa Trough
Kim, Jong-Hak ; Choi, Weon-Hack ; Bae, Jae-Seok ; Yoon, Sung-Bum ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 268~276
Potential tsunamis generated in Okinawa Trough were simulated for the investigation of the propagation characteristics in the southwestern sea of Korean Peninsula. Shallow waters in the continental shelf of East China Sea and deep waters in Okinawa Trough play an important role in the propagation characteristics of the tsunamis generated in this region. The propagation characteristics can be classified into two phases according to the stage of propagation. In the first phase, the tsunamis propagate both northeast and southwest along the deep water of the trough. In the second phase, the tsunamis enter the continental shelf of the East China Sea at right angles to topographic contour lines. Simulated results show that the tsunamis generated in the Okinawa Trough give a weak influence to the southern and western coasts of Korea due to the special topography of the southwestern sea of Korean Peninsula.
Higher Order Coordinates Conversion for UTM Projection
Seo, Seung-Nam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 277~290
In order to apply UTM coordinates conversion in zones larger than
wide, a new conversion formula, based on the 12th expansion of Taylor series, is derived which is shown to be an extension of Thomas' formula(1952). Some examples of coordinate conversion between WGS84 and UTM are presented and convergences of computational results are also tested according to the order of formula. The present conversion formula can be used to make rectangular coordinate grid systems for numerical models to compute long wave propagation such as tide or tsunami around Korea.
The Multidirectional Random Wave Diffraction in a Partial-Reflecting Harbor due to a Submarine Pit
Kim, Sung-Duk ; Lee, Hong-Sik ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 291~299
The present study is to estimate the effects of diffracted wave fields in a harbor and around harborentrance due to random waves, when a navigation channel is dredged in the vicinity of the a harbor entrance. The cross sections of harbor boundary are considered to be partial or full reflection in this study. The numerical simulation has been performed by the boundary element method, which is to discrete segments of pit- and harbor- boundary with the algorism of auto generated elements. The incident wave conditions are specified using discretized forms of the Mitsuyasu's frequency spectrum and directional function. The results of the present numerical simulation agreed well with those of the published experimental data. It is shown that the ratios of wave height reduction are about 20% for the case of fully reflecting boundary, and 10% for the case of partially reflecting boundary by the effect of placing a pit, respectively.
Reliability Analysis and Evaluation of Partial Safety Factors of Breakwater Armor stones Considering Correlation between Wave Height and Wave Steepness
Kim, Seung-Woo ; Suh, Kyung-Duck ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 300~309
The partial safety factors of armor stones have been calculated on the assumption that all random variables are independent one another. However, wave height and wave steepness are not independent in the van der Meer's formula of armor stones but they are correlated. In the present study, we calculated the partial safety factors considering the correlation and compared them with those of other researchers who did not consider the correlation. The correlation between wave height and steepness is closely related to the variability of wave period. As the variability of wave period decreases, the correlation between wave height and steepness becomes strong, and hence the calculation results with and without consideration of the correlation show more difference. Therefore, the correlation should be taken into account in the calculation of partial safety factors in the area where the variability of wave period is small.
Water Temperature and Salinity Variation Analysis in the Inter-Tidal Zone, South of Ganghwado, Korea
Cho, Hong-Yeon ; Koo, Bon-Joo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 310~320
Water temperature and salinity variation patterns were analysed using the CTD data measured in the Yeochari, Dongmakri and Donggeomdo intertidal zone, south of Ganghwado. Only the data during the submersion period of the measurement stations were used in this analysis. It is clearly shown that the correlation between air and water temperatures is very low and the water temperature variation shows clearly the opposite patterns as the tidal elevation increases and decreases. Whereas, the salinity change shows the similar pattern of the tidal elevation change pattern because the salinity change pattern could be described as the increasing function from the shoreline to offshore regions due to the continuous ground-water inflow in the adjacent watersheds. The salinity is increased from the submersion time to the high tide and decreased from the high tide to the exposure time.
Uncertainty Analysis of a Coastal Physical Model in Gyeonggi Bay and Han River Estuary
Kim, Jeong-Dae ; Jeong, Shin-Taek ; Cho, Hong-Yeon ; Jung, Kyung-Tae ; Ko, Dong-Hui ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 20, issue 3, 2008, Pages 321~331
A model has been constructed in this study for the investigation of physical characteristics of the Gyeonggi Bay and Han River estuary. MIKE 21 HD (HyDrodynamics) has been used for the uncertainty analysis of the tide of the Gyeonngi Bay and Han River estuary. A total of 15 model experiments have been performed for the hydrodynamic parts and the analysis of results have been made in terms of RMSD (Root-mean square deviation) which has been frequently employed in the suitability analysis of hydrological data since the introduction by NERC(1975), U.K. A smaller value of RMSD indicates the more suitability of a parameter to the model. Analysis of the hydrodynamic results has shown that RMSD of the mean tidal range has the largest value of 0.1148 at Yeomha channel while has the smallest value of 0.0400 at Yeonphyong-do, indicating that the uncertainty in the mean tidal range on near-shore side is larger than that of offshore side. Experiment with reduced water depth by 10% has produced a most significant increase in RMSD. It is therefore implied that the model response changes more sensitively to water depth rather than grid sizes, open boundary forcing and river discharge.