• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1817-1819
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• 2001

For an efficient calculation of scattering matrix of planar transmission line with step discontinuity. Mode Matching Method combined with Vector Finite Element Method is adopted. Calculating effective widths are replaced with their respective equivalent planar waveguide corresponding to the microstrip width, Propagation Constant is calculated from the Vector finite element. Mode matching method is used for deriving scattering parameters.

• 대한전기학회논문지
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• 제41권1호
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• pp.89-94
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• 1992

In this paper, the static limit of Helmholtz equation is discussed for the analysis of wave scattering in a wave scattering in a waveguide. Boundary integral equation method is used to formulato the scattering process in the exterior of the scatterer and finite element method in the interior of the scatterer. And hybrid ray-mode method is used to provide the Green's function in the waveguide. The proposed algorithm is applied algarithm is applied to a sample problem with arbitrary scatterer in a waveguide. The results are compared with those of static analysis.

• 산업기술연구
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• 제9권
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• pp.79-85
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• 1989

In this paper, the static limit of Helmhortz equation is discussed in the analysis of acoustic wave scattering in a waveguide. Boundary integral equation method is used to formulate the scattering process in the exerior of the scatterer and finite element method in the interior of the scatterer. And hybrid Ray-Mode Method is used the provide the Green's function of the waveguide. The proposed algorithm is applied to a sample poblem with arbitrary scatterer in a waveguide. The results are compared with those of Laplace's equation which is the governing equation in the static problems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1213-1215
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• 1994

The shape of lossy material inside a waveguide matched load is optimally designed to give low reflection over a given frequency range. The 3 dimensional vector finite element mettled is used as an analysis tool which does not generate spurious mode. The optimizing process used in this parer is the Powell technique. The designed load gives the low reflection about -30 dB around 10GHz with 1.5 wavelength of the load length.

• 반도체디스플레이기술학회지
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• 제22권3호
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• pp.21-27
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• 2023

In this article, a plate-type megasonic cleaning system with cooling pins is proposed for the sliced ingot, which is a raw material of silicon (Si) wafers. The megasonic system is operated with a lead zirconate titanate (PZT) actuator, which has high electric resistance, thus when it is being operated, it dissipates much heat. So this article proposes a megasonic system with cooling pins. In the design process, finite element analysis was performed and the results were used for the design of the waveguide. The frequency with the maximum impedance value was 998 kHz, which agreed well with the measured value of 997 kHz with 0.1 % error. Based on the results, the 1 MHz waveguide was fabricated. Acoustic pressures were measured, and analyzed. Finally, cleaning tests were performed, and 90 % particle removal efficiency (PRE) was achieved over 10 W power. These results imply that the developed 1 MHz megasonic will effectively clean sliced ingot wafer surfaces.

• 한국전자파학회논문지
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• 제8권5호
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• pp.486-487
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• 1997

본 논문은 CPW 불연속 중 개방단, 연결된 접지면을 갖는 개방단, 캡, 개방단 CPW 스터브에 대한 순수 용량 성 집중소자 등가회로를 제시하였으며, 불연속의 불리적 차원과 주파수 함수로써 등가회로의 커패시턴스값을 나 타내었다. 커패시턴스값은 3차원 유한차분 시간영역볍(3D-FDTD)을 적용하여 계산한 주파수 영역 산란 파라미 터로부터 이끌어냈다. 개방단, 연결된 접지변을 갖는 개방단 및 캡 불연속에 대해 FDTD으로 계산한 커패시턴스 값을 3차원 유한 차분볍(3D- FDM)으로 계산한 준정적 결과와 비교하였다.

• 한국소음진동공학회논문집
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• 제23권7호
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• pp.605-616
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• 2013

An important source of noise from railways is rolling noise caused by wheel and rail vibrations induced by acoustic roughness at the wheel-rail contact. In the present paper, characteristics of rail vibration and radiated sound power from concrete slab tracks for domestic high speed train(KTX) is investigated by means of a numerical method. The waveguide finite element and boundary element are combined and applied for this analysis. The concrete slab track is modelled simply with a rail and rail pad regarding the concrete slab as a rigid ground. The wave types which contribute significantly to the rail vibration and radiated noise are identified in terms of the mobility and decay rates. In addition, the effect of the rail pad stiffness on the radiated power is examined for two different rail pad stiffnesses.

• 한국소음진동공학회논문집
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• 제25권8호
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• pp.575-582
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• 2015

This paper deals with the dispersion relation of the waves sustained in a cylindrical shell submerged in the fluid. The waveguide finite method and the boundary element method are used to predict the dispersion characteristic of the cylindrical shell. The dispersion diagram of the cylinder is estimated from the eigenvalue problem and the forced vibration response. It follows that the water-loading leads to the decrease of the cut-on frequencies and the phase speeds of the bending waves. On the contrary, the longitudinal waves and the torsional waves are hardly affected by the fluid, and therefore the order of the cut-on frequencies of the waves is changed. The acoustic dispersion diagram is also estimated from the forced acoustic response to identify the characteristics of the wave radiated to the fluid. It follows that the acoustic waves on and near the surface of the cylinder are the same as those in the structure. But at the far field the acoustic waves caused by subsonic waves e.g., the bending waves disappear as the increase of the distance. Conclusively, the characteristics of waves in cylindrical shells are significantly affected by water-loading in terms of the cut-on frequency, the wave speed, the order of the cut-on and radiation.

• 한국전자파학회논문지
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• 제12권7호
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• pp.1175-1181
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• 2001

본 논문에서는 도파관 안에 전파의 진행에 대해 단면 방향으로 놓인 임의의 모양의 iris를 해석하기 위한 효율적인 반복 유한 요소법을 제안하였다. 불연속 구조 부근의 적은 숫자의 요소만으로도, 몇 번의 경계 조건의 수정 과정을 통해 전형적인 유한 요소법으로 정확한 해를 구할 수 있음을 보였다. 제안한 방법의 타당성을 보이기 위해, 구형 도파관 내의 원형 iris를 해석하고 유한 요소 경계 적분법을 이용한 결과와 비교하였다.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.406-412
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• 2018

In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.