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최재연 남서울대학교 공학연구센터 1999 공학연구 Vol.1 No.-
The scattering characteristics of the rectangular waveguide which has step discontinuities are analyzed by the modified TEmnx mode-matching method in the consideration of the higher-order modes generated at the discontinuity of the rectangular waveguide. The modified TEmnx mode-matching method needs less memory and CPU time than those of the generalized TEmn-TMmn mode analysis, and improves convergency. Two cases of discontinuity, a transformer, an E-plane corrugated filter and the combination of a transformer and an E-plane corrugated filter in rectangular waveguide are analyzed. The scattering characteristics of each passive component obtained by this method show notable differences between results with and without considering the higher-order modes.
최재연 남서울대학교출판국 2010 남서울대학교 정보통신 논문집 Vol.7 No.3
A half-paraboloidal reflector impulse radiating antenna with dual TEM source driven by short pulse excitation signal has been designed. To obtain greater front-radiating power and better directivity, offset feeding by dual TEM source inside the focal length is applied to improve the performance of paraboloidal reflector impulse radiating antelma. Simulation results show that this proposed impulse radiating antenna with dual source inside the focal length remarkably increased the front radiating field intensity more than 60% on bore-sight. Moreover, narrower beamwidth and better front radiating directivity were obtained.
최재연 남서울대학교출판국 2011 남서울대학교 정보통신 논문집 Vol.8 No.1
신호를 검출하는 방식은 비동기 방식과 동기 방식으로 나뉜다. 비동기 방식은 구성이 간단하지만 성능 개선에 제약을 받는다. 따라서, 일반적으로 성능을 중요시하는 시스템은 구조가 복잡하더라도 동기식 신호 검출법을 사용한다. 동기식 신호 검출은 신호의 존재 유무를 확인하는 것과 신호의 종류를 판별하는 것으로 나뉜다. 본 논문에서는 동기식 신호 검출 방식을 이용하여 신호의 존재 유무와 신호의 종류를 판별하고 이에대한 성능을 평가한다. Key Words : Coherent, Signal Detection, Pulse repetition, Wavelet
최재연 남서울대학교 2008 남서울대학교 논문집 Vol.14 No.-
Radiation fields from the unit current source at the interface of an anisotropic uniaxial superstrate-substrate are calculated. The Green's function in the spectral domain which is necessary for analyzing a microstrip antenna by the moment method is derived. In order to consider the effect of anisotropy of the dielectric layer, radiation fields from an x-directed unit current source is obtained and radiation patterns are also calculated by changing the permittivity and thickness of the anisotropic dielectric layer. Key Words : X-band, Microstrip, Method of Moment, Green's function
최재연 남서울대학교 2008 남서울대학교 논문집 Vol.14 No.2
In this paper, the electromagnetic scattering from the 2-dimensional hemisphere on the infinite plane is analyzed using UTD. The incident field is scattered by the hemisphere in the form of the reflected and surface diffracted field. In analyzing the scattered field, Keller's GTD can not predict the correct electromagnetic field in the transition region and the surface diffracted field. These electromagnetic field in the transition region and the surface diffracted field is analyzed using UTD. Considering the satellite communication environment, incident field is assumed to be plane wave, and hemisphere is treated as a perfect conductor. The result obtained in this paper can be applied to the analysis of scattering characteristics by dome-shaped man-made or natural structures. Key Words : UTD, GTD, Fock, Diffraction
최재연 남서울대학교출판국 2008 남서울대학교 정보통신 논문집 Vol.5 No.1
In this paper, we propose All-Optical WDM Buffer System for resolving contention problem of packets in Optical Packet Switching System. The proposed system consists of tunable wavelength converters based on SOA, N×N AWG, and fiber delay lines. This structure can reduce ASE and cross-talk noise because the buffering is achieved from passing packets through each different delay line determined by converting the wavelength of input packet. We also perform buffering experiment for two 50ns optical pulses, and it proves that the proposed system works as expected.
최재연 남서울대학교 1997 남서울대학교 논문집 Vol.3 No.-
The broadside coupled coplanar waveguide(BCCPW) shielded with the rectangular waveguide is analyzed by applying the Galerkin's method in the spectral domain. Characteristic parameters are obtained respectively when BCCPW is symmetric and unsymmetric with regard to the suspended dielectric substrate. Characteristic impedances and effective dielctric constants of BCCPW are also obtained by varying the height of the dielectric substrate and the width of the center and the ground strip in terms of transmission modes.