• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.468-473
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• 2004

The objective of this paper is to analyze the characteristics of wave transmission through various junctions in coupled beams. The in-plane vibration as veil as the out-of-plane vibration are generated due to the wave conversion at the junctions in the coupled beams. The out-of-plane vibration is associated with propagation of out-of-plane waves (flexural waves). The in-plane vibration is associated with propagation of in-plane waves (longitudinal and torsional waves). In order to effectively reduce vibration and structure-borne noise, it is necessary to understand the characteristics of wave conversion at various junctions in the coupled structures. The numerical results in this paper have showed the characteristics of wave transmission through various junctions in coupled beams. Those could be helpful to designer to develop the idea to reduce vibration and structure-borne noise.

• 한국소음진동공학회논문집
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• 제24권12호
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• pp.999-1006
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• 2014

Mindlin plate theory includes the shear deformation and rotatory inertia effects which cannot be negligible as exciting frequency increases. The statistical methods such as energy flow analysis(EFA) and statistical energy analysis(SEA) are very useful for estimation of structure-borne sound of various built-up structures. For the reliable vibrational analysis of built-up structures at high frequencies, the energy transfer relationship between out-of-plane waves and in-plane waves exist in Mindlin plates coupled at arbitrary angles must be derived. In this paper, the new wave transmission analysis is successfully performed for various energy analyses of Mindlin plates coupled at arbitrary angles.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.174-194
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• 2015

In this paper, an Energy Flow Analysis (EFA) for coplanar coupled Mindlin plates was performed to estimate their dynamic responses at high frequencies. Mindlin plate theory can consider the effects of shear distortion and rotatory inertia, which are very important at high frequencies. For EFA for coplanar coupled Mindlin plates, the wave transmission and reflection relationship for progressing out-of-plane waves (out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave) in coplanar coupled Mindlin plates was newly derived. To verify the validity of the EFA results, numerical analyses were performed for various cases where coplanar coupled Mindlin plates are excited by a harmonic point force, and the energy flow solutions for coplanar coupled Mindlin plates were compared with the classical solutions in the various conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.435-447
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• 2019

Energy Flow Finite Element Analysis (EFFEA) is a promising tool for predicting dynamic energetics of complicated structures at high frequencies. In this paper, the Energy Flow Finite Element (EFFE) formulation of complicated Mindlin plates was newly developed to improve the accuracy of prediction of the dynamic characteristics in the high frequency. Wave transmission analysis was performed for all waves in complicated Mindlin plates. Advanced Energy Flow Analysis System (AEFAS), an exclusive EFFEA software, was implemented using $MATLAB^{(R)}$. To verify the general power transfer relationship derived, wave transmission analysis of coupled semi-infinite Mindlin plates was performed. For numerical verification of EFFE formulation derived and EFFEA software developed, numerical analyses were performed for various cases where coupled Mindlin plates were excited by a harmonic point force. Energy flow finite element solutions for coupled Mindlin plates were compared with the energy flow solutions in the various conditions.

• Geomechanics and Engineering
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• 제17권3호
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• pp.295-305
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• 2019

The bedding plane has a significant influence on the effect of blasting fragmentation and the overall performance of underground mining. This paper explores the effects of fragmentation of the bedding plane and different angles by using the numerical analysis. ANSYS/LS-DYNA code was used for the implementation of the models. The models include a dynamic compressive and tensile failure which is applied to simulate the fractures generated by the explosion. Firstly, the cracks propagation with the non-bedding plane in the coal with two boreholes detonated simultaneously is calculated and the particle velocity and maximum principal stress at different points from the borehole are also discussed. Secondly, different delay times between the two boreholes are calculated to explore its effects on the propagation of the fractures. The results indicate that the coal around the right borehole is broken more fully and the range of the cracks propagation expanded with the delay time increases. The peak particle velocity decreases first and then increases with the distance from the right borehole increasing. Thirdly, different angles between the bedding plane and the centerline of the two boreholes and the transmission coefficient of stress wave at a bedding plane are considered. The results indicated that with the angles increase, the number of the fractures decreases while the transmission coefficient increases.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.128-135
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• 1997

The indirect boundary integral equation is formulated to analyze the behavior of a cavity in a multilayered half-plane subjected to earthquake waves. This formulation uses the fundamental solutions that are numerically calculated by the generalized transmission and reflection coefficient method. The free surface of the cavity without external excitation influences the behavior of the half-plane. Consequently this analysis adds the consideration of scattering-field into the analysis and the total motion field of the cavity is decomposed into the free-field and scattering-field motions. The free-field motion is obtained from the modification of the transmission and reflection coefficient method. The scattering-field motion is calculated is calculated by the indirect boundary value problem which has the ficticious boundaries and sources. In this study, P wave, SV wave, SH wave, and Rayleigh wave are analyzed respectively.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.127-131
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• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside a conducting screen of finite thickness has been considered in the case that the transverse electric(to the slit axis) polarized plane wave is incident on a slit. The problem is solved numerically by the method of moments and the results are compared with those obtained from an equivalent circuit suitable for a case in which the slit width is infinite and the structure is modified to the two partially overlapped conducting planes. It is observed that when the cavity is resonated, the effective slit width reaches its maximum value of $1/\pi$ wavelengths, irrespective of the actual slit width and the incidence angle. When the thickness of the conducting plane is much smaller than the wavelength, the numerical results for the effective slit width(or transmission width) agree well with those obtained from the equivalent circuit, even though the slit is as narrow as the thickness of the conducting plane.

• 한국통신학회논문지
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• 제10권4호
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• pp.193-200
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• 1985

정현적으로 진동하는 유전체 경계면으로 부터의 전자파(TE)의 반사와 투과현상을 진동하는 임의의 순간에는 등속운동이라 가정하여 Lorentz변환을 확대 적용하여 이론적으로 해석하였다. 전자파의 경계면에 입사각, 운동매진의 유선율 및 진동속도의 함수로써 반사, 투과계수, 전력반사, 투과율의 평균치를 수치계산하여 검토하였다.

• 한국통신학회논문지
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• 제11권6호
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• pp.371-378
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• 1986

정현적으로 진동하는 유전체 경계면에서 전자파(TM파)의 반사, 투과현상을 진동하는 임의의 순간에 등속운동이라 가정하여 Lorentz 변환을 확대적용하여 이론적으로 해석하였다. 전자파의 입사각, 운동매질의 유전율, 진동속도의 함수로써 반사, 투과특성을 수치계산 검토하였다.

• 한국통신학회논문지
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• 제15권3호
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• pp.232-242
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• 1990

외부 평면파에 의해 유기되는 단일 전송선로의 EMI(Electromagnetic Interference) 전류에 관한 Smith의 해석법을 이용하여 연쇄 접속된 전송선로의 부하 EMI전류를 구한다. 동일한 특성 임피던스를 갖는 선로가 연쇄 접속 되었다는 가정하에 수치계산을 하여 Smith의 연구 결과와 비교한 결과 두 결과가 잘 일치함을 확인하였으며, 선로의 폭과 길이가 각각 1/10로 줄어들면 부하 EMI 전류는 약 40dB 정도 감소함을 알 수 있었다.