• Proceedings of the Korea Water Resources Association Conference
• /
• 2001.05a
• /
• pp.236-241
• /
• 2001

• Proceedings of the Korea Water Resources Association Conference
• /
• 2002.05b
• /
• pp.1298-1303
• /
• 2002

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.6
• /
• pp.832-838
• /
• 2021

Recently, reports of marine accidents of small fishing vessels less than 10 tons have been increasing. In this study, the characteristics of the motion response in regular waves were analyzed using computations for these ships. Small vessels less than 10 tons are classified by size and used for marine accident investigations. Therefore, the motion response analysis was performed on three small fishing vessels of different sizes. In the case of the head sea, it was confirmed that as the speed of the vessel increased in the long wavelength region, the motion responses of heave and pitch became large. The motion response of the smallest 3-ton fishing vessel was greater than that of the other sizes of fishing vessels. The maximum value of the roll motion shifted to the long wavelength region as the speed gradually increased in the bow sea, regardless of the size of the ship. In all the three small fishing vessels, it was found that the roll motion was the greatest at 15 knots, the highest speed in both bow and beam seas. When sailing in the head sea and bow sea conditions, lowering the speed is one of the effective approaches to reduce the effects of the vertical and lateral plane motions. The roll motion caused by the beam wave showed a tendency to increase rapidly only at a specific wavelength regardless of the speed and the size of the vessel. It was confirmed that the roll motion was significantly reduced with forward speed in the stern wave compared to the bow wave. As there is a specific region where the maximum value of the hull motion response appears depending on the size and speed of the ship, an operation method that can minimize the effect of this motion should be considered and implemented.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2003.11a
• /
• pp.161-164
• /
• 2003

본 연구는 집중력, 기억력 및 학습 능력의 뇌기능 증진을 위한 의식적인 손 운동에 관련된 연구이다. 우선 효과적인 재활을 위한 손가락 운동 패턴을 연구하였다. 단순한 손가락 운동(Simple Finger Movement ; SFM) 패턴과 의식적인 손가락 운동(Intentional Finger Movement ; IFM)패턴을 비교하였다. 다음으로 각각 두 패턴 운동을 시켜 피험자의 집중력과 학습 능력의 증진을 검증하고자 한다. SFM 패턴과 IFM 패턴의 비교와 집중력과 학습 능력의 증진의 검증은 뇌파(mid $\alpha$파)를 이용하였다. 실험은 먼저 SFM 패턴의 운동을 시키고 다음에 IFM 패턴의 운동을 시키는 실험을 하였다. 결과적으로 IFM 패턴에서 mid $\alpha$ 파의 증가가 이루어졌음을 측정함으로써, IFM 패턴이 뇌의 집중력과 학습 능력을 증진시킨다는 결과를 얻었다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.2
• /
• pp.200-206
• /
• 2013

The paper was investigated on the mooring forces(or tension) and motion response characteristics for a 8-point mooring floating dock in regular waves using a commercial code(AQWA). To achieve the aim of the research, a numerical simulation was adapted on an inner port environment condition, which the water depth is 10 meters, significant wave amplitude(1.05 m). wave period(3.85 sec), wind speed(20.21 m/s), wind and current direction ($90^{\circ}$), incident waves(${\chi}=180^{\circ}$, $135^{\circ}$ and $90^{\circ}$). The dimension of the numerical model is length(140 m), breadth(32 m), depth(14.6 m). The maximum length of a mooring line is 120m. We can expected that roll and pitch motions appeared in beam seas better than head sea. the mooring forces also indicated higher in bean seas than in head seas including wind forces.

• Geophysics and Geophysical Exploration
• /
• v.15 no.3
• /
• pp.121-128
• /
• 2012

Absorbing boundary conditions are used to mitigate undesired reflections that can arise at the model's truncation boundaries. We apply a complex frequency shifted perfectly matched layer (CFS-PML) to elastic wave modeling in the frequency domain. Modeling results show that the performance of our implementation is superior to other absorbing boundaries. We consider the coefficients of CFS-PML to be optimal when the kinetic energy becomes to the minimum, and propose the modified CFS-PML that has the CFS-PML coefficient ${\alpha}_{max}$ defined as a function of frequency. Results with CFS-PML and modified CFS-PML are significantly improved compared with those of the classical PML technique suffering from large spurious reflections at grazing incidence.

• Journal of the Society of Naval Architects of Korea
• /
• v.38 no.3
• /
• pp.47-53
• /
• 2001

When a ship advancing in waves is subjected to impact forces or irregular forces, the motion analyses for ship are convenient for being calculated in the time domain. The added mass, wave damping coefficients, wave exciting forces and mean drift forces are calculated by 3-Dimensional panel method used the translating pulsating Green function in the frequency domain and the motion equations which are considered by the memory effect due to waves are numerically solved by using the Newmark-$\beta$ method in the time domain. The motion analyses are carried out for a Series 60($C_B=0.7$) moving in irregular waves. The items of calculation are 6-degree motions, accelerations at the fore and after position, numbers of deck wetness and numbers of exposure at ship-bottom, etc. Moreover, the thrust addition in waves is examined by considering the time mean drift forces in the motion equations of time domain.

• Journal of the Society of Naval Architects of Korea
• /
• v.38 no.2
• /
• pp.10-18
• /
• 2001

The very large floating structure which can be used for as airport may be as large as several kilometer long and wide. The first order wave forces as well as wave drift forces are very important forces on such a very large floating structures. In the present study, the time simulation of motion responses for dolphin-moored VLFS in waves is presented. The hydrodynamic coefficients and wave forces involved in the equations are obtained from a three-dimensional panel method in the frequency domain. The horizontal drift forces and mooring forces for dolphin systems are taken into account. As for numerical example, time domain analyses are carried out for a VLFS(Phase I) in irregular wave condition.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.7 no.4
• /
• pp.313-320
• /
• 1995

A numerical analysis on the wave deformation in the shallow water region is performed for the case of two intersecting wave trains of the same frequency on uniformly sloping beaches. This model is based on the consideration of wave energy balance and wave action conservation, and iteratively solved the set of conservation equations of both mass and horizontal momentum. Using the computed results, the wave deformations in accordance with the variation of the parameters luck as incident wave angie and wave height in deep water which influences the variation of wave hight and mean water level under the intersecting wave trains in the shallow water region. are considered.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2005.05a
• /
• pp.233-236
• /
• 2005

Polarization filtering based on the multicomponent complex trace analysis method is performed to reject Rayleigh waves and to enhance S waves. To test the polarization filter, synthetic seismic data were constructed for a simple two-layer model based on the finite difference method. Rayleigh waves with elliptic motion are eliminated effectively and P and S waves with linear motions are well separated each other.