• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.1-7
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• 2001

Mainly, Floating Breakwaters (FBs) have been constructed in many coastal regions due to the advantages of the coastal environment and construction cost. In general, the FB becomes fixed or its width broadened because the movement of the FB comes to be large and its the wave control function lower for the long period incident waves. This study discusses the wave control function of two-rowed Fixed Floating Breakwater (FFBs) that have narrower width than that of the one-rowed FFB by using numerical approach. Boundary Element Method (BEM) based on the Green formula and Eigenfunction Expansion Method (EEM) are applied to evaluate the three-dimensional wave transformation near the wave fields of two-rowed FFBs. The validity of the present study is confirmed by comparing it with the results of Ijima et al. (1974) and Yoshida et al. (1992) for the one-rowed Fixed Floating Structure. It is revealed that the wave control function of two-rowed FFBs is more effective than that of the one-rowed FFB.

• The Journal of the Acoustical Society of Korea
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• v.13 no.2E
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• pp.5-13
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• 1994

Simulation of the target-scattered echo requires the understanding of scattering mechanism at the highlight points. In this paper, the basic assumption of Highlight Model is reviewed through the analyzed data obtained in the acoustic water tank experiment. The analysis shows that the scattering mechanism involves pulse elongation and frequency shift as elements of target-scattered echo, and that the internal structures affect the temporal response of the target-scattered echo significantly. The band-limited impulse response or Green's function due to the diffraction from highlight points of internal structures is not mere delta function, but acts like a filter, which causes frequency shift and is elongated in time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.3 s.258
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• pp.365-372
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• 2007

Revisited in this paper are Green's functions for unit concentrated forces in an infinite orthotropic Kirchhoff plate. Instead of obtaining Green's functions expressed in explicit forms in terms of Barnett-Lothe tensors and their associated tensors in cylindrical or dual coordinates systems, presented here are Green's functions expressed in two quasi-harmonic functions in a Cartesian coordinates system. These functions could be applied to thin plate problems regardless of whether the plate is homogeneous or inhomogeneous in the thickness direction. With a composite variable defined as $z=x_1+ipx_2$ which is adopted under the necessity of expressing the Green's functions in terms of two quasi-harmonic functions in a Cartesian coordinates system Stroh-like formalism for orthotropic Kirchhoffplates is evolved. Using some identities of logarithmic and arctangent functions given in this paper, the Green's functions are presented in terms of two quasi-harmonic functions. These forms of Green's functions are favorable to obtain the Newtonian potentials associated with defect problems. Thus, the defects in the orthotropic plate may be easily analyzed by way of the Green's function method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.108-113
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• 2014

This paper presents the influence on the transmission characteristics of swelling in rectangular waveguides for Q-band. We derived the Green's functions of the waveguide with eigenfunction expansion method. The reflection coefficient of the waveguide with a swelling is calculated by using internal impedance in order to investigate the influence of swelling in the waveguide. In order to check the validity of the theoretical analysis, the calculated reflection coefficients are compared with the measured results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.722-729
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• 2013

This paper presents the influence on the transmission characteristics of dimensional tolerances of rectangular waveguides usually used as a low-loss transmission line in the millimeter-wave band. We derived the Green's functions of the waveguide with eigenfunction expansion method. The reflection coefficient of the waveguide with a post is calculated by using internal impedance in order to investigate the influence of dimensional tolerances of the waveguide. In order to check the validity of the theoretical analysis, the calculated reflection coefficients are compared with the measured results.

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.52-56
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• 2009

The design method of a four-port stripline circulator with a single ferrite disk is proposed using Green's function method. The four-port circulator gives the flexibility of the design of the communication system. Two cascaded three-port circulators has been used as a four-port circulator. However, if a four-port circulator with a single ferrite disk replace the present four-port circulator, then it will give less weight and volume and so has the advantage in satellite application.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.175-178
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• 2005

TM plane-wave scattering from finite rectangular grooves in a conducting plane is systematically analyzed with the overlapping T-block method. Multiple rectangular grooves are divided into several overlapping T-blocks to obtain the fast CPU time, CAD applicability, and wide versatility. The scattered fields are obtained in simple closed forms including a fast-convergent integral.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.144-154
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• 1998

A functionally graded material is a nonhomogeneous material, which is composed of several different materials to maintain structural rigidity and endure high temperature loads. An analytical method is presenter to solve the unsteady heat conduction equation for nonhomogeneous materials. A one-dimensional infinite plate made of functionally graded material is considered. The approximate Green's function solution is derived and to be used to obtain the temperature distribution them the stress distributions may be obtained. The volume fraction, the porosity, the stress difference, and the stress ratio are the design parameters and are to be used to set up a systematic design procedure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.9
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• pp.764-771
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• 2007

The objective of the present work is to evaluate the evaporation heat flux of deposited droplet on the hot surface by using of inverse heat transfer technique. On the basis of measured temperature, a integral form solution is determined for the transient temperatures beyond the two positions by using Green's function technique. This method first approximates the temperature data with a half polynomial series of time. we compared this result with constant radius model in single phase regime, nucleate boiling regime, film boiling regime respectively. this paper performed the experiments as following conditions: (a)the surface temperature is within the range between $80^{\circ}C\;and\;160^{\circ}C$ in the conduction, (b) droplet diameter are 2.4 and 3.0mm. (c) surface roughness is $0.18{\mu}m$.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.505-507
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• 2001

실루엣 에지를 찾거나 디스플레이하는 것은 컴퓨터 비전에서부터 비사실적인 렌더링(nonphotorealistic rendering)에 이르기까지 여러 응용분야에서 중요한 의미를 가진다. NPR(nonphotorealistic rendering)에서 가장 초점을 두는 것은 컴퓨터로 렌더링된 결과가 사람이 그린듯한 효과를 줄 수 있느냐에 있다. 본 논문에서는 점진적 메쉬와 실루엣 에지 렌더링을 통해 사람이 임의의 객체를 점진적으로 스케치하는 효과를 보여 줄 수 있는 방법을 제시한다. 다단계 메쉬 생성은 대용량의 메쉬를 효율적으로 다루기 위한 것으로 점진적인 렌더링이나 전송, 상세도, 제어 등에 이용되는 기술이다. 메쉬 간략화에서는 볼륨과 정계를 보존 할 수 있는 간략화 기법을 이용하였다. 간략화 수행시 원본 메쉬에 대한 히스토리를 저장할 수 있는 점진적 메쉬(Progressive Mesh)구조를 구성한 뒤 기본메쉬를 점진적으로 상세하게 해 나감으로써 실루엣 렌더링을 수행하게 된다. 실루엣 에지에 대해 파라미터화된 브러쉬 함수(Parameterized Brush Functions)를 적용하여 다양한 스타일로 점진적인 스케칭 효과를 낼 수 있는 기법을 제시한다.