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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Electromagnetic Engineering and Science
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Journal DOI :
The Korean Institute of Electromagnetic Engineering and Science
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Volume & Issues
Volume 13, Issue 10 - Dec 2002
Volume 13, Issue 9 - Oct 2002
Volume 13, Issue 8 - Sep 2002
Volume 13, Issue 7 - Aug 2002
Volume 13, Issue 6 - Jul 2002
Volume 13, Issue 5 - Jun 2002
Volume 13, Issue 4 - Apr 2002
Volume 13, Issue 3 - Mar 2002
Volume 13, Issue 2 - Feb 2002
Volume 13, Issue 1 - Jan 2002
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Blind Source Separation Algorithm using the Second-Order Statistics
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 107~114
The problem of blind signal separation of independent sources consist in retrieving the source from the observation of unknown mixtures of unknown sources. In this paper, we propose a technique for blind signal separation that can extract original signals from their non-stationary mixtures observed in a ordinary room. The proposed method implements blind signal separation by minimizing a non-negative cost function that achieves the minimum when the second-order cross-correlation value of the observed signals becomes zero. The validity of the proposed method has been verified by a computer simulation and experiment that extracts two source signals from their mixtures observed in a normal room.
A Study on the Bandwidth of Compatible ETC System
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 115~122
In this paper, we proposed a new technique to be compatible the passive with active ETC system. Now the TTA is making a Standard of the Active DSRC System. So It is necessary to be compatible the developed and running passive ETC system with the developing active ETC system. So we proposed the direct conversion method without performance a decreasing of passive DSRC system using a similar bandwidth of the active ETC system. Simulations carried out and the results show the difference between the conventional and proposed method.
Design and Fabrication of 5-Bit Broadband MMIC Phase Shifter
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 123~129
5-bit broadband MMIC phase shifter has been designed and fabricated. For the broadband performance, 11.25
bit have been designed with Lange coupler and 180
bit has been implemented by using shorted coupled line with Lange coupler and
-network of transmission line. Due to Lange coupler with large size, the Lange couplers have been folded far circuit size reduction. Low loss PIN diode has been utilized as a switch for each bit. Fabricated 5-bit broadband phase shifter shows the measured results that RMS phase error of 5 major phases is 3.5
, maximum insertion loss is 12.5 dB, and maximum input and output return loss are 7 dB and 10 dB, respectively. The size of fabricated phase shifter is 6.5
A Da7a-Recycling Sign Algorithm for Adaptive Equalization
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 130~135
A new Sign algorithm which has improved convergence speed is presented. The data-recycling technique, whose coefficients are multiply adapted in a symbol time period by recycling the received data, is applied to Sign algorithm which has few multiplications. Sign algorithm has very few multiplications and is the most easily implemented, but it gives small rate of convergence relative to others. The proposed algorithm combines the advatage of Sign algorithm, few multiplications, and the virtue of Data-Recycling LMS algorithm, simplicity and fast convergence. The results of computer simulation show that the proposed algorithm has 2 times faster convergence rate than that of LMS algorithm. Comparing to Data-Recycling LMS algorithm, in similar convergence conditions, it requires half fewer multiplications.
Analysis of Stopband Characteristics for 1D Photonic Band-Gap Structures
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 136~145
In this paper, we facilitate the analysis of 1D PBG structure using a ABCD matrix formulation after converting field parameters into circuit parameters. Dispersion diagrams for an infinite 1D PBG structure are derived and compared with the frequency responses for a finite structure (N=10). When the proposed method is adopted, the analysis and synthesis of 1D PBG structures become very convenient.
Linearization Up to the Saturation Region of Poller Amplifiers
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 146~154
This paper presents a linearization technique up to the saturation region of power amplifiers. The predistorter gain polynomials which have optimum coefficients are introduced. Power amplifiers are most efficient when operated near the saturation region. Compensating the amplifier nonlinearities with these predistorter gain polynomials, the efficiency of the amplifier can be maximized. Simulation results demonstrate that the adjacent channel power ratio (ACPR) is improves by about 63 ㏈ at the band edge. The convergence and reconvergence characteristics of the linearizer are also satisfactory.
Analysis of SAR Reduction Methods for Mobile Communication Handsets
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 155~163
In this paper, we propose SAR reduction methods based on power conservation relation, After defining SRF(SAR Reduction Factor) for a more quantitative discussion of effective SAR reduction methods, many kinds of simulation have been performed. We compare the SAR by a flip type handset with that of folder type one. It is found that in a typical position of handsets over a human head, the SAR when using the folder type is about 30 % smaller than that when using the flip type. The effects of ferrite material when using flip type handset are shown to be not considerable when using a folder type.
Probe Design and Fabrication for Measuring Near Field
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 164~169
This paper reports on design and fabrication of near field probe operating at 300~3000 MHz. Design parameters are extracted by equivalent circuit of E-field probe and simulation using S parameter is performed to predict probes performance. The probe consists of a dipole antenna with 3.25 mm length, a zero bias Schottky diode and a highly resistive transmission line. A TEM cell was used for performance evaluation.
Variational Calculations for Higher Order Mode Cut-off Frequencies of Symmetrical Striplines by the Conformal Mapping
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 170~175
The cut-off frequencies of higher order modes in a symmetrical stripline are calculated using the variational finite element method combined with the conformal mapping. The conformal mapping is used to Improve the modeling of the infinite transverse extents of a stripline. And then the finite element method is employed to solve the variational equation in the transformed finite region. Comparisons with numerical results found in the literature validate the presented method.
Application of Turbo Code for Digital Audio Broadcasting (DAB) System
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 176~187
The digital Audio Broadcasting (DAB) system adopts Coded OFDM(COFDM) for channel coding. The COFDM is a combined technique of multicarrier transmission(OFDM) and punctured convolutional coding with viterbi error correction. Because the channel coding is an important topic for OFDM systems, this paper proposes a new turbo coded OFDM system that replaces the existing RCPC codec by a turbo codec without modifying the puncturing procedure and puncturing vectors defined in the standard DAB system for compatibility. The performance of a new system is compared to that of the conventional system under the frequency selective Rician fading channel and the frequency selective Rayleigh fading channel in conjunction with DAB transmission mode I suitable for the terrestrial single frequency network(SFN) broadcasting. The standard system's performance was improved with the aid of turbo codec.
Comparison of Correlation Algorithms between GTEM Cell and Semi-Anechoic Chamber
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 188~195
This paper statistically verifies two correlation algorithms by comparing the data of GTEM cell to those of semi-anechoic chamber (SAC). Correlation algorithms considered in this paper are 3 and 15 position methods, which simulate the EMI test for an equipment under test (EUT) over the ground plane by using the radiated power from EUT located within GTEM cell. Also, the results obtained by two algorithms are compared with the theoretical values calculated from an ideal dipole model. From the results, it was found that the data obtained by two correlation algorithms and SAC have a strong correlation. In addition, the EMI data by 3 position method showed higher than those by 15 position method and SAC measurements.
The Analysis of Radio Interference between Korea and China/japan using Split-step DMFT Algorithm
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 196~208
Since radio interference has occurred in the TRS frequency band in the south coastal area, Korea from 1994, similar interference has been observed in the mobile-cellular frequency band. Measurement showed that the sources of the radio interference are those from the base stations for digital cellular systems in Japan. This because the receiving frequency of the base stations in Korea is same as the transmitting frequency of the base stations in Japan. Since the distance between Korea and Japan is 240 ~ 300 km, we can conclude that the main reason of the interference is ducting. In this paper a ducting channel is modeled by split-step DMFT algorithm, and simulation results for measured index profile far east coast and west sea area are analyzed.
Design of a Waveguide Broad-wall Longitudinal Slot Array Antenna of X-type Monopulse Axes
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 208~216
In this paper, the design method of a waveguide broad-wall longitudinal slot array monopulse antenna of X-type monopulse axes is presented, and the method is verified through manufacture and measurement. In the antenna design of this paper, the antenna size is small and the monopulse axes are X-type. Thus, the common continuous aperture distribution fuction is not suitable and the power balance among antenna quadrants should be considered. Also, since the waveguide height is reduced into 0.1 wavelength, the modelling of the slot characteristics is not simple. Thus, in this paper, the aperture distribution is optimized by using random number, and the balance among the quadrants is achieved by applying the quadrant weighting factor during the aperture optimization process. Also, the moment method procedure is accelerated by applying the interpolation technique to some part of the moment matrix, and the moment method procedure is added to the array synthesis program as a subroutine so that the slot characteristics can be calculated directly when it is required. Based on this method, a antenna of 28dBi is designed and manufactured. It is found that the antenna characteristics is similar to design data.
Analysis of the Stepped-Impedance Low Pass Filter using Sub-Gridding Finite-Difference Time-Domain Method
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 13, issue 2, 2002, Pages 217~224
One of the dominant aspects governing the accuracy of the FDTD method is the size of the spatial increment used in the model. The effect of having reduced cell size is to increase the computational time and memory requirements. To overcome these problems, sub-gridding technique can be used. This implies that the application of a sub-grid cell would provide improved accuracy without increasing the run time and computer resources considerably. In this paper, we describe the three dimensional sub-gridding technique that is applied to model only the fine structure region of interest. The detailed solution procedure is described and some test geometries were solved by both uniform grid and sub-grid models to validate the suggested approach. While keeping the accuracy, the computational time becomes 6 times faster and the memory requirement is reduced by a factor of 2.5 comparing to the conventional FDTD approach.