• 전자공학회논문지A
• /
• 제33A권5호
• /
• pp.85-93
• /
• 1996

The far-zone scattered field patterns of a hyperbolic reflector antenna are analyzed by using uniform geometrical theory of diffraction(UTD). The main objective of this paper is to obtain the higher order diffraction contributions which provide the continuity over the shadow boundaries of the first order solution. to obtain the scattered magnetic field characteristics, the scattered field components of the secodn-order diffraction, diffraction-reflection, diffraction-reflection-diffraction terms are added to the result of the previous research. The results of the present research are compared to those of the first order solution and the method of moments. One can observe the improvemtn of the current approach over the first order solution. also, the results of the present method agree very well with those of the moment methods especially in the transition regions near the first order diffraction shadow boundaries.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.667-670
• /
• 1999

As the number of reference patterns increase in the text dependant speaker recognition, the recognition performance of the system degrades. So, if reference patterns were decreased the high recognition rate can be obtained. It’s because the speaker recognition can obtain the high discrimination. In this paper, to decrease the number of reference patterns, we choose candidate reference patterns to perform pattern matching with test pattern by high order component of the reflection coefficients of the uttered speech signal Consequently the total recognition rate of the proposed method is about 2% higher than that of the conventional method.

• 전자공학회논문지D
• /
• 제35D권10호
• /
• pp.7-12
• /
• 1998

본 논문에서는 다양한 물질에 접촉해 있는 여러 형태의 동축선 끝단에서의 전파반사를 FDTD 방법으로 해석하였다. 3차원의 해석 구조를 2차원 원통 좌표계로 변환하여 매우 효율적으로 계산할 수 있었다. FDTD 계산결과를 통하여, 주파수가 높아지거나 또는 동축선로의 직경이 증가할 때 동축선 끝단에서의 반사크기가 줄어든다는 것을 알았다. 이 방법을 적용하여 다층 구조에서의 전파반사도 해석하였으며, 측정결과와 이론식을 이용하여 본 해석 방법을 검증하였다.

• 전자공학회논문지D
• /
• 제34D권9호
• /
• pp.36-42
• /
• 1997

Optical filters with graded index profiles are designed by applying the fourier transform to a riccati equation which governs the reflection and transmission characteristics of inhomogeneous refractive index distributions. The inhomogeneous refractive index profile of an optical filter with specified target spectrum is obtained through iterations. The spectra response of the inhomogeneous refractive index layers are analyzed by using runge-dutta numerical method to solve the differential euations of the amplitude and the phase of reflection coefficient derived from the riccati equation and the results are in good agreement with the resutls obtained by using matrix method.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
• /
• pp.288-295
• /
• 2003

The relationship between the reflection number obtained from seismic reflective survey and the rock strength value obtained from TBM excavation is examined, and the procedure of the conversion from the reflection number to the rock strength value is proposed. Subsequently, geostatistical method is employed to evaluate the rock properties ahead of the tunnel face and around the tunnel with good precision, using both the seismic reflective survey data and the TBM driving data for the purpose of the tunnel driving and enlargement. The applicability of this evaluation method is examined at the actual tunnel site.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2009년도 특별 심포지엄
• /
• pp.73-87
• /
• 2009

Geophysical survey for unconformity-type uranium deposit applied to this study area in Athabaska Basin, Canada were carried out airborne TEM and magnetic, resistivity-induced polarization (DC-IP), puser seismic reflection and well-logging method. The results of airborne survey interpreted the lithological boundary, geological structures, and conductors. Also, these results decided to main targets for ground DC-IP survey. The Low resistivity and the high chargeability slices of 3D modeling interpreted from DC-IP survey response for conductors related to hydrothermal alteration zones and fault-controlled graphitic zones occurring at the unconformity-type uranium deposit, and they confirmed by diamond drilling. Seismic results interpreted to lake bottom surface, alluvium layer and intra-sandstone faults. We suggest the resonable field data acquisition of DC-IP method on the land or the lake in Athabaska Basin.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
• /
• pp.156-157
• /
• 2000

The amplification method using evanescent wave coupling has a long history and has been widely used as a new lasing method, especially, in the waveguide optics$^{(1)}$ . In particular, it has been observed experimentally that when the light wave propagating in a dielectric medium is totally reflected at the planar interface between the dielectric and a pumped active medium, the reflectance may be greater than unity, i.e., amplification is possible$^{(2)}$ . There were several attempts by other authors to explain this enhanced internal reflection (EIR) classically$^{(3)}$ . They commonly introduced a complex refractive index for the active medium with its imaginary part being negative, and this scheme was also used to describe an amplification process in a waveguide having active-cladding region$^{(4)}$ . However these theories are phenomenological, using macroscopic constants, and therefore a microscopic theory is needed to understand EIR in a fundamental level. (omitted)

• 자원환경지질
• /
• 제32권5호
• /
• pp.495-502
• /
• 1999

Common-mid-point (CMP) seismic data on a dipping layer have have a stacking different from a horizontal layer velocity and the reflection points on data are dispersed to many positions. Therefore, the CMP data are not stacked well by the conventional stacking method using the horizontal layer velocity. The CMP gather can ideally stacked by applying dip-moveout(DMO) processing. Hence, modern seismic processing indludes DMO as an essential routine step. DMO processing techniques are broadly categorized by two, Fourier transform and integral methods, each of which has many different computational schemes. In this study, the dip-decomposition technique of the Fourier transform method is used to test the DMO effect on the synthetic scismic data generated for dipping structures. Each of constnat offset sections NMO corrected by using the layer velocity of the model and DMO processed. The resulting zero-offset sections for many offsets are stacked. The stacked sections with DMO processing show the structural boundaries of the models much better than those without DMO processing.

• 한국컴퓨터그래픽스학회논문지
• /
• 제3권1호
• /
• pp.9-15
• /
• 1997

지금까지 대부분의 렌더링(rendering)에 대한 연구는 빛의 반사(reflection)와 광원과 물체 표면에서의 조명(illumination)에 대한 것이었다. Kolb가 [1]에서 밝힌 것처럼 카메라와 렌즈에 대한 연구는 렌더링 연구에서 중요한 요소임에도 불구하고 연구 결과가 많지 않았다. 본 논문에서는 카메라 렌즈에서의 범프 맵핑과 새로운 렌즈개발을 위한 프레임 워크를 소개한다. 이 프레임 워크는 새로운 렌즈 개발에 쓰일 수 있고, 범프 맵핑은 그림 2,3,4,5에서처럼 어안 렌즈등 여러 다른 렌즈들과 혼합되어 다양한 효과를 거둘 수 있다.

• 대한자원환경지질학회:학술대회논문집
• /
• 대한자원환경지질학회 2002년도 춘계 공동학술발표회
• /
• pp.163-166
• /
• 2002

Initial velocity model close to real velocity structure of the subsurface governs the quality of image of prestack depth migration. Geophysicists employ velocity estimation tools such as velocity analysis (curvature method, coherency inversion), tomography and waveform inversion. We present a reflection tomography that parameterizes the subsurface into the movable blocks. By interpreting the depth-migrated section or stacked section, we can design an initial constant velocity model having only impedance boundaries. We use shooting-raytracing method that allows us to calculate the Jacobian-matrix efficiently.