• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.27 no.1
• /
• pp.1-8
• /
• 2015

Recently, constructions of coastal structure including wind turbine structure have increased at southwest shore of Korea. There is a big difference of tide which rage from 3.0 m to 8.0 m at south and wet shore of Korea, respectively. In such ocean circumstance, large scour may occur due to multi-directional tidal current and transverse stress of the wind. therefore scour surrounding wind turbine structure can make system unsafe due to unexpected system vibration. In this study, hydraulic resistance capacity, i.e., critical velocity and critical shear stress, was evaluated by RCT. Uni-directional and bi-directional hydraulic resistance capacities of the samples which were consolidated by different preconsolidation pressures were correlated with soil resistivities of same samples. According to the correlation, it is possible to estimate hydraulic resistance capacity from electrical resistivity of soil. Through the updating the correlation for various soil types, it is expected that the hydraulic resistance capacity of whole construction site will be simply determined from the electrical resistivity.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.1
• /
• pp.20-27
• /
• 2013

Seabed settlement underneath a coastal structure may occur due to wave loading generated by storm surge. If the foundation seabed consists of sandy soil, the possibility of the seabed settlement may be more susceptible because of generation of residual excess pore-water pressure and cyclic mobility. However, most coastal structures, such as breakwater, quay wall, etc., are designed by considering wave load assumed to be static condition as an uniform load and the wave load only acts on the structure. In real conditions, however, the wave load is dynamically applied to seabed as well as the coastal structure. In this study, therefore, a real-time wave load is considered and which is assumed acting on both the structure and seabed. Based on a numerical analysis, it was found that there exists a significant effect of wave load on the structure and seabed. The deformation behavior of the seabed according to time was simulated, and other related factors such as the variation of effective stress and the change of effective stress path in the seabed were clearly observed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.15 no.4
• /
• pp.214-223
• /
• 2003

A reliability analysis is straightforwardly applied to the sloped coastal structures against the random wave overtopping. A reliability function can be directly derived from a empirical formula in which may take into account many variables associated with the random wave overtopping. The probability of failure exceeded the allowable overtopping discharge can be evaluated as a function of dimensionless crest height with some reasonable statistical properties and distribution functions of each random variable. Some differences of probabilities of failure occurred from variations of the slopes of structures as well as types of armour are investigated into quantitatively. Additionally, the effects of the crest width of units placed in front of the concrete cap on the probability of failure may be analyzed. Finally, the sensitivity analyses are carried out with respect to the uncertainties of random variables. It is found that the overall characteristics similar to the known experimental results are correctly represented in this reliability analyses. Also, it should be noted that the probabilities of failure may be quantitatively obtained for several structural and hydraulic conditions, which never assess in the deterministic design method. Thus, it may be possible for determination on the crest height of sloped coastal structures to consider the probability of failure of wave overtopping, by which may be increased the efficiency of practical design.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.1
• /
• pp.25-33
• /
• 2008

Water waves are generated mainly by winds in open seas and large lakes. They carry a significant amount of energy from winds into near-shore region. Thereby they significantly contribute to the regional hydrodynamics and transport process, producing strong physical, geological and environmental impact on coastal environment and on human activities in the coastal area. Furthermore an accurate prediction of the hydrodynamic effects due to wave interaction with offshore structures is a necessary requirement in the design, protection and operation of such structures. In the present paper surface and internal waves scattering by thin surface-piercing and bottom-standing vertical barriers in a two-layer fluid is analyzed in two-dimensions within the context of linearized theory of water waves. The reflection coefficients for surface and internal waves are computed and analyzed in various cases. It is found that wave reflection is strongly dependent on the interface location and the fluid density ratio apart from the barrier geometry.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.4
• /
• pp.258-267
• /
• 2004

Coastal and harbor structures, which are constructed for the beach protection and coastal zone development, often cause the severe beach erosion problem resulted from changes of longshore sediment transport. In this study, we present a new methodology to estimate the longshore sediment transport rates using the measured data of beach profiles or shorelines. The methods is applied for the prediction of longshore sediment transport rates along Kailua beach, Hawaii and shorelines in the vicinity of Anmok Harbor, Korea.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.6
• /
• pp.379-385
• /
• 2019

Dynamic Tidal Power, which is a kind of tidal power generation, requires huge structures, because it is conducted by using the phase difference caused by the diffraction effect of tides. Economic feasibility is most demanded for practical use, and various studies have been conducted for this purpose. In this study, unlike existing methods, several structures were installed to improve it by increasing power generation. The flow changes around the structures were studied, and it was found that proper spacing between structures was necessary for efficient power generation.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.1
• /
• pp.1-6
• /
• 2016

The effect of reducing wave overtopping by use of the wave return wall was quantitatively analyzed based on physical experiments. The overtopping discharge for the arc seawall and the inclined seawall was measured and compared with the predictive formula that estimates reduction of overtopping by the wave return wall. When the overtopping discharge was relatively large ($q/{\sqrt{gH^3_s}}>10^{-3}$), the agreement in terms of overtopping reduction rate was fairly good between the prediction and the measurement. For the condition of smaller overtopping than the above criterion, however, the discrepancy was large between the predicted and measured result. In this context, it is required to develop a better formula for estimating reduction of wave overtopping by the wave return wall.

• 어항어장
• /
• s.89
• /
• pp.69-71
• /
• 2010

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2010.04a
• /
• pp.231-233
• /
• 2010

최근 어항에도 친환경항만을 건설하기 위한 노력이 국제적으로 확산되고 있으며, 우리나라에서도 어항의 정비 및 재개발부분에서 적극적으로 수질개선을 위한 기술 적용이 본격화 되고 있다. 본 연구는 우리나라 남해의 소규모 어항 및 해수욕장에 슬릿형 해안 구조물이 시공된 실해역의 실측자료와 수치해석을 통해 현장적용성의 분석을 수행하였다. 수치실험으로는 파랑작용 평형방정식을 이용하는 SWAN 모델을 구성하고 수리모형실험에서 분석된 실린더 슬릿형 방파제의 반사와 투과계수를 모텔에 도입하였다. 수치실험은 한국해양연구원의 전해역 심해설계파 추정 보고서 II (2005)중의 심해설계파 제원을 사용하였으며, 대상해역의 1970년~2006년 (37년간) 관측된 연최대 풍속자료를 이용하여 모델에 반영하였다. 설리항에서 S, SSE, SE계열의 파랑의 내습에 대한 분석을 수행하였으며, 그 결과 구조물이 항내에서 정온도가 유지되며 해수순환에도 이점이 있음을 현장관측 자료분석과 수치실험결과를 통하여 확인할 수 있었다.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.4
• /
• pp.287-294
• /
• 2012

Sedimentary environment in coastal zone has been changing due to a large number of coastal structures and continuous coastal development. As a result, the environment has been changing. In particular, the economic and environmental damage can occur due to cohesive sediment transport closely related with the fate of pollutants. Due to large sea wall construction the ebb dominance in the Mokpo coastal waters has been clearer. Cohesive sediment transport was simulated by the EFDC model. The simulated SS showed good agreements with the observed SS. From the sensitivity analysis of sediment parameters, we found out that the erosion rate, the critical shear stresses for erosion and deposition, and the settling velocity are important factors in cohesive sediment transport modeling.