• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.5
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• pp.285-290
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• 2013

Both full linear and shallow water edge waves are compared to get a better understanding of edge wave behavior. By using method of separation of variables, we are able to get solution of full linear edge wave presented by Ursell (1952) without derivation. The shallow water edge waves show dispersive features despite being derived from shallow water equations. When bottom slope is mild enough, shallow water edge wave tends to linear edge wave and has some advantages of manipulation. Solution of edge wave generated by a moving landslide of Gaussian shape is constructed by an expansion of shallow water normal modes. Numerical results are presented and discussed on their main features.

• Geophysics and Geophysical Exploration
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• v.1 no.3
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• pp.183-187
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• 1998

Seismic waveform estimation is based on the assumption that the seismic trace tying a well is one dimensional convolution of the propagating seismic waveform and the reflectivity series derived from well logs (sonic and density). With this assumption, the waveform embedded in a seismic trace can be estimated using a Wiener match filter. In this paper, I experimented a preprocessing procedure that applies both on the seismic trace and on the reflectivity series. The procedure is based on the assumption that the travel time can be estimated better from the seismic trace and that the instantaneous reflectivity values can be measured better on the well log. Thus the procedure is, 1) start-time adjustment and dynamic differential stretches are applied on the sonic log, and 2) seismic amplitudes are balanced such that the low frequency part of the seismic are matched to that of the reflectivities derived from well logs.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.3
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• pp.189-194
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• 2001

The present study describes the Bragg reflection of monochromatic water waves propagating over a train of doubly-sinusoidally varying topographies. A numerical model based on the boundary element method is firstly verified by calculating reflection and transmission coefficients of waves over a trench. Calculated solutions are compared with those of the eigenfunction expansion method. The model is then used to simulated reflection of monochromatic water waves propagating over doubly-sinusoidally varying bottom topographies. Obtained reflection coefficients are compared with those of available laboratory measurements, those of the eigenfunction expansion method and the extended mild-slope equation. A reasonable agreement is shown.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.91-96
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• 2002

The present research describes the Bragg reflection of obliquely incident waves propagating over sinusoidally varying topographies. A numerical model based on the boundary element method is employed. Wave numbers providing Bragg reflection are calculated and compared to theoretical predictions. The reflection coefficients obtained from this model are also compared with those of the eigenfunction expansion method. A very good agreement is observed.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.185-189
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• 1991

GaAs Schottky 접촉 전송선을 전극으로 하는 진행파형 광변조기의 특성이 분석되었다. 초고주파의 전파특성은 quasi-TEM 모델에 의해 분석되었으며, 고유치 방법과 유효 굴절율법을 결합하여 광파의 전파특성을 분석하였다. 또한 이를 통해 Schottky 접촉 전송선 및 광도파로의 기하학적 변수에 따라 진행파형 광변조기의 성능지수를 계산함으로써 최적 설계조건을 계산하였다.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.396-401
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• 2005

In this study, the assumed mode method using characteristic polynomials of Timoshenko beam is applied to the free vibration analysis for the stiffened plate of ship tank side in contact with water. The hydro-elastic effect of the fluid-structure interaction is considered by fluid velocity potential, derived from boundary conditions for fluid and structure, and utilized in the calculation of added mass matrix using assumed modes. To verify the validity and effectiveness of the presented method, free vibration analysis for the stiffened plates in contact with finite and infinite fluids have been carried out and its results were compared with those obtained by a general purpose FEA software.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.677-684
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• 2002

In this study, a finite element model is employed to simulate the diffraction of waves caused by a change of water depths. The model is firstly applied to the estimation of reflection coefficients of monochromatic waves over a sinusoidally varying topography. Predicted coefficients are compared with those of the eigenfunction expansion method and laboratory measurements. A good agreement is observed. The model is then used to investigate effects of heights of bottom topography and number of ripples on variation of reflection coefficients of monocromatic water waves.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.805-814
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• 2000

A numerical model based on the boundary element method is employed to describe diffraction of monochromatic water waves due to varying topographies. The model is firstly verified by comparing obtained reflection and transmission coefficients of waves over a trench to those of the eigenfunction expansion method. The model is then used to investigate the Bragg reflection of waves over sinusoidally varying topographies. Calculated reflection coefficients are compared to available laboratory measurements and semi-theoretical results. A reasonably good agreement is observed.served.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.1-16
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• 1999

Differential equations and its numerical solution program using Turbo-C were formulated to describe the radical distribution and average displacement amplitude of vibrating dehydrated contact lens(HEMA) driven by sinusoidal or rectangular pressure. The natural resonant frequency of the lens diaphram(thickness 0.08mm, diameter 14mm, curvature radius 8mm) was measured to be 5730 Hz from the extrapolation of frequency vs addedmass to the diaphram curve. The Young's modulus of the lens was measured to be $4{\times}10^9$ Pa with altering the original shape. The effect of parameters such as thickness, effective radius, damping coeff., amplitude of driving pressure on the vibration characteristics was illustrated by the computer simulation of the derived program. When the frequency of driving pressure coincides with the integral multiple of fundamental resonance frequency of the lens the wave pattern changes from arc to bell-shape along the radial position of the diaphram. If this happens to the contact lens on the cornea in vivo, it might create the feel of pull of the lens due to the increased rise of central part of the lens.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.227-230
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• 2018

자동차는 현대사회에서 보편화한 편리한 운송수단으로써 사람이 생활하는 어느 곳에서나 활용되고 있다. 최근 ICT와 차량을 융합한 커넥티드 카는 운전자에 의해 모든 동작이 결정되는 특징을 가지고 있어 도난 및 오용되니 않게 적합한 사용자 인증이 필요하다. 운전자가 음주를 하게 되면 정상적인 차량 운행이 불가능하여 교통사고가 발생할 수 있다. 이를 방지하기 위해 운전자의 현재 상태를 파악하여 차량을 운전하는데 이상이 없는지를 파악하고 부적합할 경우 차량 운행을 제어할 수 있는 수단이 필요하다. 스마트키, 지문 인식 등 차량에 대한 사용자 인증의 방식이 존재하지만, 인증과 동시에 사용자의 현재 상태를 파악하는 방법은 없는 상황이다. 본 논문에서는 고유한 생체 정보인 ECG 파형의 특징을 이용하여 사용자 인증과 동시에 운전자의 현 상태를 파악하는 안전한 차량 제어 시스템을 제안하고자 한다.