• Journal of the Society of Naval Architects of Korea
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• v.59 no.2
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• pp.64-71
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• 2022

In this paper, we simulate the collision of a solitary wave on a vertical wall in a uniform water channel and investigate the effect of damping on the amplitude attenuation. In order to take into account the damping effect, we introduce the Stokes damping whose dissipation is dependent on the velocity of wave motion on the surface of a thin layer of oil. That is, we use the improved Boussinesq equation with Stokes damping to describe the damped wave motion. Our work mainly focuses on the amplitude attenuation of a propagating solitary wave, which may depend on the Stokes damping together with the initial position and initial amplitude of the wave. We utilize the method of images and a powerful numerical tool (functional iteration method) for solving the improved Boussinesq equation, yielding an effective numerical simulation. This enables us to find the amplitudes of the incident wave and reflected one, whose ratio is a measure of the (wave) amplitude attenuation. Accordingly, we have shown that the reflection of a solitary wave by a vertical wall is dependent on not only the initial amplitude and position of a solitary but the Stokes damping.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.166-167
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• 2003

파랑ㆍ흐름의 공존장에서 그 간섭작용은 Tidal inlet 와 하구부근와 같은 천해영역에서 중요한 물리적 현상이다. 이러한 파ㆍ흐름간섭현상은 파랑의 파고, 스펙트럼과 파향등을 현저하게 변화시키고, 하구와 inlet부근에 출현하는 사주(砂洲)등의 발생기구 및 해빈 안정화에 관계하는 중요한 요인이기 때문에 이에 대한 적절한 해석이 필요하다. 본 보고에서는 확장형 부시네스크방정식을 토대로 한 수치모델을 통하여 파ㆍ흐름 공존장에서의 적용성을 검토하고자 한다. (중략)

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.35-40
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• 2006

In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.5
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• pp.341-350
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• 2023

In this paper, numerical experiments are performed to examine the collision between a solitary wave and a wave-packet (dispersive wave) in shallow water. We attempt to introduce the improved Boussinesq equation governing the experiments, which is solved by using a semi-analytical approach, called Pseudo-parameter Iteration method(PIM). Using various numerical experiments, we have observed that the wave-packet (propagating dispersive wave) experiences a phase shift after collision with a solitary wave. This phenomenon may be considered as a nonlinear wave-wave interaction in shallow water.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.221-232
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• 2021

Most of measurement sensors used for maintenance are continuously exposed to various environmental factors such as transportation and rainfall, so the possibility of breakage increases gradually. The maintenance measurement sensor of domestic subway tunnel shows an average of 14.2% to 14.8% of loss rate after about 5 to 6 years from installation, and it shows a sensor loss rate of about 13.9% in case of foreign countries. As a result, it can be seen that an average of 15% of maintenance measurement sensors at home and abroad cannot send measuring values after 5~6 years. In order to continuously collect accurate data, measurement data must be recovered by performing repair or replacement of the sensor, but some lost measurement sensors are buried after installation. So, there are many difficulties in repairing sensors, including cost and time. Therefore, in this paper, we propose lost measurement sensor data estimation technology based on data trend analysis using adjacent sensors.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.128-134
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• 2003

Numerical study on interactions of waves and currents has considerable practical interests in coastal and ocean engineering. And wave-current interactions strongly influence wave characteristics, current profiles, and forces on offshore structures. Presence of currents affects wave properties such as wave height and wave profiles. Furthermore, in case of the irregular waves, it is more complicated problem. The propose of present study, using the one-dimensional wave-current numerical model is based on the extended Boussinesq equation(Madsen, 1991) and an alternative form of wave-current dispersion relation(Mohiuddin, 1999, 2000) including wave action concept, is to simulate wave propagation in a current field including the irregular waves and discuss applicability of the model in a wave-current field.

• Journal of the Korean GEO-environmental Society
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• v.5 no.2
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• pp.51-62
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• 2004

Granular compaction piles have the load bearing capacity of the soft ground increase and have the settlement of foundation built on the reinforced soil reduce. The granular compaction group piles also have the consolidation of the soft ground accelerate and have the liquefaction caused by earthquake prevent using the granular materials such as sand, gravel, stone etc. However, this method is one of unuseful methods in Korea. The Granular compaction piles are constructed by grouping it with a raft system. The confining pressure at the center of bulging failure depth is a major variable in relation to estimate for the ultimate bearing capacity of the granular compaction piles. Therefore, a share of loading is determined considering the effect of load concentration ratio between the granular compaction piles and surrounding soils, and varies the magnitude of the confining pressure. In this study, method for the determination of the ultimate bearing capacity is proposed to apply a change of the horizontal pressure considering bulging failure depth, surcharge and loaded area. Also, the ultimate bearing capacity of the granular compaction piles is evaluated on the basis of previous study on the estimation of the ultimate bearing capacity and compared with the results obtained from laboratory scale model tests. And using the result from laboratory model tests, it is studied increase effect of the bearing capacity on the granular compaction piles and variance of coefficient of consolidation for the ground.