• 한국통신학회논문지
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• 제9권3호
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• pp.113-119
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• 1984

誘電體圓柱가 축에 수직한 방향으로 正弦的으로 振動할 때 이에 의한 電磁波의 散亂을 고찰하였다. 순간적인 振動速度와 같은 等速度가 있다고 가정하고 그 순간은 特殊相對性理論에 기초하여 散亂界를 구하고 이를 한 振動週期에 확대 적용하였다. 平均散亂電力의 角度分布와 散亂斷面績, 레이다斷面績의 평균을 平面波의 入射角, 振動振幅과 振動角速度로 표시되는 순간진동속도의 최대치를 변수로 하여 변화상태를 규명하였다. 冷플라즈마의 圓柱가 진동하는 경우도 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.

• 전자공학회논문지D
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• 제35D권4호
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• pp.24-31
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• 1998

The far-zone magnetic field patterns of a E-plane horn antenna with various edge structures are analyzed using UTD. The ray tracing method is used to lacate the shadow boundaries, and then GO and UTD are utilized to evaluate the incident, reflected, diffracted, surface diffaracted, and the second order diffracted, diffracted-reflected, and diffracted-reflected-diffracted waves existing in each region of interest. By doing this, we analyzed the effects of flanges or caps connected on the edge of a horn antenna on the side lobe and back lobe levels. Also, the validity of this paper is proved by comparing the analytical results with those of measurement and method of moment presented in the reference.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.201-204
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• 2006

In the side scan sonar method, use is made of the back-scattering, at low grazing angles of incidence to the seabed, of relatively high-frequency acoustic waves radiated in a fan-shaped beam from a transducer contained in a towed body. The fan beam is oriented so that the wider angle is in the vertical plane (scan range) and the narrower angle in the horizontal plane (beam width) with the axis of the beam normal to the ship track. The display of the returns is usually realized as a series of closely spaced intensity-modulated lines on a paper recorder or computer screen display. In this way a two-dimensional picture of the seabed is build up.

• 천문학회지
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• 제34권4호
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• pp.247-249
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• 2001

The accretion disks are usually supposed symmetric to reflection on the Z=0 plane. Asymmetries in the flow are be ver-y small in the vicinity of the compact accretor. However their existence can have a important role in the case of subkeplerian accretion flows onto black holes. These flows lead to strong heating and even to the formation of shocks close to the centrifugal barrier. Large asymmetries are due to the development of the KH instability triggered by the small turbulences at the layer separating the incoming flow from the out coming shocked flow. The consequence of this phenomenon is the production of asymmetric outflows of matter and quasi periodic oscillations of the inner disk regions up and down the Z=0 plane.

• 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.

• Earthquakes and Structures
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• 제9권3호
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• pp.577-601
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• 2015

The thermomagnetic effect on plane wave propagation at the liquid-solid interface with nonclassical thermoelasticity is investigated. It is assumed that liquid-solid half-space is under initial stress. Numerical computations are performed for the developed amplitude ratios of P, SV and thermal waves under Cattaneo-Lord-Shulman theory, Green-Lindsay theory and classical thermoelasticity. The system of developed equations is solved by the application of the MATLAB software at different angles of incidence for Green and Lindsay model. The effect of initial stress and magnetic field in the lower half-space are discussed and comparison is made in LS, GL and CT models of thermoelasticity. In the absence of magnetic field, the obtained results are in agreement with the same results obtained by the relevant authors. This study would be useful for magneto-thermoelastic acoustic device field.

• 한국철도학회논문집
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• 제3권2호
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• pp.77-83
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• 2000

This study proposes the integrity evaluation of the bogie frame using ultrasonic fractography analysis. Analysis objectives in this study are to investigate fracture planes of damaged zone by the A-scan method. The surface condition of fracture planes shows degree of degradation by the stress concentration. The detection of the natural defects in the bogie frame is performed using the characteristics of echodynamic pattern in ultrasonic signal. Results of ultrasonic testing agree fairly well with those of actual fracture plane. In quantitative fractography analysis, microstructures of actual fracture plane turned out to be intergranular and transgranular fracture. Proposed ultrasonic fractography analysis in this study can be used for the integrity evaluation of the bogie frame.

• 한국정보통신학회논문지
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• 제8권3호
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• pp.529-534
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• 2004

밀리미터파는 안개 또는 연기등에 의한 시계불량 환경에서의 고해상도 거리 및 영상정보 획득에 사용될수 있으며 광대역 통신에서도 활용되고 있다. 그러나 밀리미터파 시스템의 성능평가를 위해서는 밀리미터파 전파에 관한 이론 및 실험적인 고찰을 필요로 한다. 밀리미터파의 강도변화 및 MCF는 대기현상이 밀리미터파 전파에 미치는 영향을 표시한다. 본 논문에서는 QOM 기법을 이용하여 기상자료에 의하여 얻어질수 있는 MCF로부터 안테나 초점평면에서의 강도분포를 효율적으로 구할수 있는 실질적인 방법을 제안하였다.

• 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.