http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Re-examination of Analytical Models for Microwave Scattering from Deciduous Leaves
Oh, Yi-Sok,Hong, Jin-Young 弘益大學校 科學技術硏究所 2005 科學技術硏究論文集 Vol.16 No.-
본 논문은 활엽수의 잎에 대한 전파 산란 모델들의 정확성을 수치 해석적 방법인 method of moment(mom)로 비교, 검증하였다. 나뭇잎에 대한 전파 산란 모델로는 Rayleigh모델, GRG모델, PO모델이 있으며, PO모델은 나뭇잎을 resistive sheet으로 근사화하여 계산했다. 잎에 대한 전파 산란 모델들의 유효영역을 method of moment의 수치적 결과와 비교하였으며 두께가 얇은 유전율 디스크에 대해서는 전파 산란 모델들의 유효영역을 확장할 수 있음을 알아냈다. 나뭇잎의 두께(0.2∼0.4mm)가 매우 얇기 때문에 GRG모델과 PO모델 둘다 나뭇잎에 대한 마이크로파 해석에 사용할 수 있다.
대퇴박근 근피판을 이용한 Fournier's gangrene치험례
이석기,이종원,이형주,임풍 大韓成形外科學會 1991 Archives of Plastic Surgery Vol.18 No.1
Fournier's gangrene is a progressive tissue necrosis of scrotum, this disease commonly occured in alcoholics and diabetic patients. 60 year old patient shows toxic symptom and even sepsis, but the scrotal content is to be spared. The treatment of this disease is adequate debridement and administration of sensitive antibiotics. If the scrotal content is exposed, the defect can be covered with skin graft, local flap, etc. But, when the scrotum shows marked fibrosis or inflammation, myocutaneous flap is inevitable. We experienced one case of scrotal defect due to Fournier's gangrene, which was successfully covered with gracilis myocutaneous flap.
오이석,손영규 弘益大學校 科學技術硏究所 1995 科學技術硏究論文集 Vol.6 No.-
The input impedance, return loss, wave propagation process, and other characteristics of a microstrip patch antenna have been analyzed using the Finite-Difference Time-Domain (FDTD) method. Among other absorbing boundary conditions(ABC), the Second order dispersive Boundary Condition(DBC) was used for front and end walls and the Mur's first order ABC was used for top, bottom, and side walls in this FDTD computation. The Current distribution on the microstrip antenna was obtained by FDTD and radiation pattern of the antenna could be computed using the current distribution. The effect of the feedign position has been also investigated in this paper.
광대역무선통신(LMDS) 마이크로스트립 패치 안테나 설계 및 제작
吳二錫,弘振榮 弘益大學校 科學技術硏究所 2001 科學技術硏究論文集 Vol.12 No.-
Design, fabrication and measurement of an LMDS microstrip array antenna are presented in this thesis. At first, basic principles for antenna design has been reviewed. Then 8x8 microstrip array antenna was designed using EM simulators at 24.5GHz. The return losses and the patterns of the microstrip array antennas were simulated using CAD tools to get optimum results. For Tx/Rx antenna, The single-fed dual resonance patch antenna drives perpendicular polarizations at two resonant frequencies from a rectangular patch radiator, using aperture coupling via a bended single-feeding line and a cross-shaped slot. The 8 X 8 array antennas were fabricated based on the simulation results and measured using the network analyzer. the measurements show that this 8x8 array antenna has the resonant frequency of 24.6GHz, the return loss of -21.3dB at the frequency, Band width of 720MHz(VSWR < 2), the gain of 25.47dBi. E-plane and H-plane of the side-lobe level are -19dB, -17dB respectively. The HPBWs of the principal E-plane and principal H-plane are 9.5?respectively.
임피던스 경계 조건을 이용한 바다 표면에서의 전파 산란에 대한 수치적 해석
오이석 弘益大學校 科學技術硏究所 1998 科學技術硏究論文集 Vol.9 No.2
In this paper, electromagnetic wave scattering from the randomly rough sea surfaces was computed using the Method of Moment/ Monte Carlo method. The integral equations of that the electric and the magnetic fields as functions of the surface electric and magnetic currents are formulated using the impedance boundary conditions. Sea surfaces are generated numerically by using the relationship between the wind speed and the surface roughness parameters which is obtained empirically. The directional rough surface generated by computer shows both vertical and horizontal skewness. Then, the electric fields scattered from the nonlinear directional rough surfaces are computed using the method of moments and the Monte Carlo method. A tapered impedance sheet was used to reduce the edge effect to improve the computation of the scatting coefficient at large incidence angles. It was shown that the computation results for sea surface scattering agreed well with the new PO model.
오이석,이원달 弘益大學校 科學技術硏究所 1997 科學技術硏究論文集 Vol.8 No.-
본 논문에서는 network analyzer와 안테나를 이용하여 Ku-밴드 레이다 시스템을 구성하고, 그 레이다 시스템을 이용하여 RCS를 정확히 측정할 수 있는 기술을 개발한다. 정확한 산란 세기를 측정하기 위해서는 레이다 시스템을 정확히 보정하는 기술(calibration technique)이 필요하다. 본 논문에서는 레이다 시스템을 정확히 보정하기 위해서 RCS를 알고 있는 sphere, cylinder, trihedral의 이론적 RCS를 구하고 보정되지 않은 레이다 시스템으로 측정한 RCS와 비교한다. 여기에서 system loss, 거리 보정, 안테나 위치 보정과 같은 오차를 줄이고 산란 특성을 정확히 계산하는 보정기술을 연구하였다.
모멘트 기법을 이용한 유전체 거친 표면에서의 전자파 산란 특성 연구
이병훈,오이석 弘益大學校 科學技術硏究所 1996 科學技術硏究論文集 Vol.7 No.2
Electromagnetic wave scattering from a one-dimensional dielectric randomly rough surface is analyzed using the Moment Method which is one of popular numerical methods. At first, a set of coupled integral equations are formulated using the wave equation, the second Green's theorem and the boundary conditions. The coupled integral equations are solved by the Moment Method for a segment of a randomly rough dielectric surface. Then, the scattering coefficients from a given dielectric rough surface is computed suing the Monte Carlo Method. The numerical results are compared with the small perturbation method (SPM) for a surface which roughness is reside in the validity region for the SPM. The numerical method is utilized for prediction of scattering coefficients from various kinds of dielectric rough surfaces.
A Semi-empirical Model for Polarimetric Radar Backscattering from Bare Soil Surfaces
Yi Sok Oh 大韓遠隔探査學會 2001 大韓遠隔探査學會誌 Vol.17 No.2
A semi-empirical polarimetric backscattering model for bare soil surfaces is presented. Based on measurements by using polarimetric scartterometers and the JPL AirSAR, as well as the theoretical models, the backscattering coefficients σ0vv σ0hh and σ0vh, and the parameters of the copolarized phase-difference probability density function, namely the degree of correlation α and the copolarized-phase-difference S, are modeled empirically in terms of the volumetric soil moisture content m(v) and the surface roughness parameters k(s) and k(l), where k=2πflc, s is the rms height and 1 is the correlation length.
Radar Remote Sensing of Soil Moisture and Surface Roughness for Vegetated Surfaces
Yi Sok Oh 大韓遠隔探査學會 2008 大韓遠隔探査學會誌 Vol.24 No.5
This paper presents radar remote sensing of soil moisture and surface roughness for vegetated surfaces. A precise volume scattering model for a vegetated surface is derived based on the first-order radiative transfer technique. At first, the scattering mechanisms of the scattering model are analyzed for various conditions of the vegetation canopies. Then, the scattering model is simplified step by step for developing an appropriate inversion algorithm. For verifying the scattering model and the inversion algorithm, the polarimetric backscattering coefficients at 1.85 GHz, as well as the ground truth data, of a tall-grass field are measured for various soil moisture conditions. The genetic algorithm is employed in the inversion algorithm for retrieving soil moisture and surface roughness from the radar measurements. It is found that the scattering model agrees quite well with the measurements. It is also found that the retrieved soil moisture and surface roughness parameters agree well with the field-measured ground truth data.