Explore the vast range of titles available.

Lee, W.D.; Jeong, Y.H., and Jeon, H.S., 2019. Groundwater flow analysis in a coastal aquifer with the coexistence of seawater and freshwater by using a non-hydrostatic pressure model. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 121-125. Coconut Creek (Florida), ISSN 0749-0208. The study proposes a new hydrostatic pressure model for flow analysis of a coastal aquifer wherein seawater and freshwater coexist. The numerical model introduces an advection–diffusion equation for salinity and temperature to trace the behaviors of seawater and freshwater in the Navier–Stokes (N-S) solver based on the porous body model (PBM) that considers the characteristics of a coastal aquifer (e.g., particle size, porosity, and shape). Furthermore, the density current is analyzed based on a state equation that determines the properties of water (density and viscosity) based on salinity and temperature. This enables the flow analysis of a coastal aquifer based on non-linear interferences between seawater and freshwater. In order to validate the proposed numerical model, a numerical constant water head permeability test device is set up, and the calculated permeability coefficient of the porous media exhibits a high degree of agreement with the value measured in the experiment. Flow simulations of a coastal aquifer are conducted based on the water level difference and salinity difference between seawater and groundwater. Additionally, hydrodynamic characteristics are analyzed from the water table, flow field, salinity distribution, and maximum penetration distance of the coastal aquifer. Specifically, an in-depth discussion of the diffusion of salinity near the shoreline and the movements of the seawater and freshwater interface is presented, which is largely absent in extant models.

Lim, C.B.; Lee, J.L., and Kim, I.H., 2019. Performance test of parabolic equilibrium shoreline formula by using wave data observed in East Sea of Korea. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 101-105. Coconut Creek (Florida), ISSN 0749-0208. This study is the validity examination of an equilibrium shoreline formula of parabolic type, which was introduced by Hsu in 1987, for real phenomena. Hsu's formula of parabolic type is practical for estimation of shoreline change after coastal or harbor structure construction. The wave data observed at Maengbang beach of East Sea of Korea and the CERC formula on longshore sediment transport were used in the present study. Performance test was conducted for the case of a shoreline change after the construction of a groyne. It was reasonable between the observed wave data and the data obtained under a wave spreading parameter, S = 3.5. However, when S increased, significant changes were observed. Thus, it is required to apply an equilibrium shoreline formula of parabolic type carefully.

Hur, D.S.; Jung, K.H.; Park, J.R., and Lee, W.D., 2019. Wave control performance of tide-adapting low-crested structure. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 116-120. Coconut Creek (Florida), ISSN 0749-0208. Low-Crested Structures (LCSs) are aesthetically apt coastal structures with wave and sand drift control functions. However, they are inappropriate in waters where the tidal range is large because the crest width and height must be above certain levels to allow the breakwater to carry out these functions. Forced wave breaking cannot be induced during high tide because the crest depth increases. Therefore, a Tide-Adapting Low-Crested Structure (TA-LCS) is proposed to overcome the problems caused by large tidal ranges. The hydraulic performance of the proposed LCS was evaluated and compared with that of a typical LCS via hydraulic model experiments. The typical LCS showed an excellent wave screening effect with an average transmission coefficient of 0.4 under the conditions of Fb/Hi=0.29–0.67 and B/Li=0.09–0.15. The wave screening performance of the new type of LCS was 9.5–28.8 % lower than that of the typical LCS. However, the wave screening performance of the new type of LCS decreased only by 9.1–10.4 % under the condition of Fb/Hi≤1 and only by 24.3 % under the condition of Fb/Hi=4. Therefore, the new type of LCS proposed in this study is expected to exhibit its wave control functions during high tide even when installed in a coastal area with a large tidal range.

Du, S.; Liang, B., and Lee, D.Y, 2019. Numerical investigation of local scour with inclined piles. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 161-165. Coconut Creek (Florida), ISSN 0749-0208. In coastal and offshore engineering applications, foundations of breakwaters, offshore wind turbine foundations and piles are often damaged by local scour induced by currents or waves, which will threaten people's property and life security. The present study focuses on the local scour around cylinder piles, which are inclined toward upstream, downstream, and lateral. A vertical pile together with the three types of inclined piles was investigated by a numerical model in clear-water scour condition. Each type of the inclined pile was simulated for five inclination angles ranging from 15° to 45°. The angle of inclination is between the pile axis and the bed normal. By solving the Reynolds Averaged Navier–Stokes (RANS) equations, steady currents around the piles are simulated with the validated model. The results show significant differences in scour and deposition for the vertical and inclined piles. Sediments transport induced by the horseshoe vortex, contracted streamlines and the wake vortices were analyzed. Upward flow and downward flow in front of the pile were seen quite contrary between downstream inclined pile and upstream inclined pile. Local scour in lateral inclined pile was found moving toward to the inclined side. Maximum scour depth for inclined piles decreases in different degrees compared to the vertical pile.

Shin, S.; Bae, I.-R., and Lee, J.-I., 2019. Physical modelling of the wave transmission over a tetrapod armored artificial reef. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 126-130. Coconut Creek (Florida), ISSN 0749-0208. Two-dimensional laboratory experiments were conducted in the wave flume to investigate the wave transmission phenomena over both impermeable and permeable artificial reef structures, which were armored with tetrapods. Different cases of the experimental conditions were included by changing permeability, relative crest height, relative crest width, wave steepness and so on. A modified empirical formula from the existing formula was proposed to predict the wave transmission coefficient over the various specifications and structural designs of the artificial reef. The proposed formula successfully predicted the wave transmission coefficients for permeable, partially permeable and impermeable structures. Therefore, in this study, the empirical formula of the wave transmission over the artificial reef was improved from the existing formula by including various permeable cases.

Duong, T.T.; Jung, K.-H.; Lee, G.-N.; Kim, D.-S.; Suh, S.-B., and Kim, M.-S., 2019. Experimental study on wave impact under deck due to regular waves. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 81-85. Coconut Creek (Florida), ISSN 0749-0208. Wave forces acting on the lower decks of offshore platforms can cause significant structural damage and play an important role in the design of offshore structures. In this study, the wave impact phenomena under horizontal decks of offshore structures were investigated with a series of laboratory experiments measuring vertical global forces and local pressure distributions on fixed horizontal plate subjected to regular waves varying wave height, wave period, and deck clearance. The local pressure data under the deck was used to assess the impulsiveness at each location for various wave conditions and deck clearances. Particle image velocimetry (PIV) technique was employed to obtain the velocity fields under the deck, which were synchronized with vertical forces and local pressure data. The water velocity profiles during wave loading under deck were compared with velocity profiles of incoming regular waves without the deck and presented the deformation of wave kinematics at each phase of the predominant vertical force change to understand the wave impact phenomena.

Yuk, J.-H. and Joh, M., 2019. Prediction of typhoon-induced storm surge, waves and coastal inundation in the Suyeong River Area, South Korea: A case study during typhoon Chaba. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 156-160. Coconut Creek (Florida), ISSN 0749-0208. Typhoon-induced storm surge and high waves caused coastal inundation and resulting coastal damages in the south-eastern coast of South Korea (the Republic of Korea), especially in the Suyeong River Area (SRA), Busan during typhoon Chaba (201618) which occurred early in October 2016. This study developed a prediction system based on weather and tide-surge-wave models to guide countermeasures against coastal inundation. The weather prediction model is named K-MPAS (KISTI - Model for Prediction Across Scales), and was optimized by KISTI to more accurately predict typhoons in the Western Pacific Ocean. The tide-surge-wave model ADCIRC+SWAN, a widely-used model, is based on a flexible unstructured grid with a more detailed grid for the region of interest (SRA). As a case study, the meteorological condition, storm-surge, and waves due to typhoon Chaba were predicted using this prediction system, and are presented and discussed in terms of the typhoon track, surface pressure, wind, storm-surge, waves, and resultant coastal inundation in the SRA. The model results were in good agreement with observations, thus this prediction system can provide a reliable service for coastal disaster management.

Yoon, J.-S.; Lee, J., and Ha, T., 2019. Development of a numerical algorithm considering tide–tsunami interaction. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 76-80. Coconut Creek (Florida), ISSN 0749-0208. The perimeter of the Pacific Ocean Basin, known as the Ring of Fire, has several sources that can produce strong earthquakes of magnitude ≥7.0. The earthquake of magnitude 9.0-9.1, occurred in 2011 off the Pacific coast of Tohoku, produced a devastating tsunami that affected the Pacific Basin. The lead time before the subsequent tsunami of such an earthquake reaches the coastal areas of the Korean peninsula varies. A tsunami from a distant location like Chile or California, USA, will take 12 h or more to reach the Korean peninsula, while that from Japan or the Ryuku Trench will take only 1–4 h. The tide–tsunami interaction may be strengthened significantly in some regions with very strong tides and could be used to predict tsunami hazards in Korea. Therefore, to develop a plan for mitigating tsunami hazards around the Korean peninsula, the tide–tsunami interaction that occurs during the propagation of a tsunami over regions with strong tides and tidal currents should be properly evaluated and its impact on a local community should be considered during numerical simulations. We developed a new numerical algorithm that includes tide–tsunami interactions for the national tsunami forecasting system. Numerical experiments using this tsunami forecasting algorithm were conducted to investigate the impact of tide–tsunami interactions as the tsunami propagates toward coastal areas of the Korean peninsula.

Lee, Y.B.; Kim, K.H; Kim, H.D; Kim, J., Kwak, K., and Park, T., 2019. High wave predictive numerical simulation for the wave alarm system. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 91-95. Coconut Creek (Florida), ISSN 0749-0208. In recent times, coastal damage has been on the increase due to rising sea levels as a result of global warming and the increasing frequency of high waves as a result of climate change. High swells and waves directly invading the coastline propagate more energy onto the shoreline than preexisting waves, causing physical damages such as coastal erosion as well as human casualties. However, an alarm system that can predict high waves by analyzing weather forecasts and transmit the information to a user in real time does not yet exist. Such a technology is necessary to prevent damage and human loss to ever increasing high swells and waves. This research aims to successfully predict high waves by using real time weather data in its simulations to detect potential danger in a user's location, as part of the larger research for the development of a high wave alarm system technology.

Laksmi, A.A.; Kim, T.K., and Lee, J.L., 2019. Numerical approaching of beach profile by using suspended sediment transport process. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 86-90. Coconut Creek (Florida), ISSN 0749-0208. The coastal process in a surf zone is very complicated, especially when the wave breaks and it associates turbulence. In a coastal area with wave angle influence the cross-shore process, the energy dissipated per unit water volume by breaking waves generate seabed sediment suspension then drive the materials to offshore along with the undertow in the swash zone. This situation could lead beach profile evolution due to the sediment erosion and deposition across an area in the surf zone. As a result, a sand bar located around the breaking line and berm at the landward region caused by overwash are formed. Furthermore, the beach profile is presumed to be in an equilibrium condition when the total positive and negative littoral transport approaches zero. The equilibrium stage which commonly used is expressed with a power of 2/3 which provide the best representative to the natural beach profile shapes. Under this concept, an analysis on the correlation between the beach profile response due to the incident wave energy and suspended sediment transport in a cross-shore view is carried out. Furthermore, this study develops a simple equilibrium beach profile prediction by analyzing the sediment characteristics and is supported by numerical modeling. Lastly, this study is expected to be practically used for coastal infrastructure design works, especially in the process of mean shoreline position prediction as the basis of the design judgements.