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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Communications and Information Sciences
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The Korean Institute of Communications and Information Sciences
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Volume & Issues
Volume 16, Issue 12 - Dec 1991
Volume 16, Issue 11 - Nov 1991
Volume 16, Issue 10 - Oct 1991
Volume 16, Issue 9 - Sep 1991
Volume 16, Issue 8 - Aug 1991
Volume 16, Issue 7 - Jul 1991
Volume 16, Issue 6 - Jun 1991
Volume 16, Issue 5 - May 1991
Volume 16, Issue 4 - Apr 1991
Volume 16, Issue 3 - Mar 1991
Volume 16, Issue 2 - Feb 1991
Volume 16, Issue 1 - Jan 1991
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Recent Trends of Universal Data Compression
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 901~913
Data compression has important application in the areas of file storage and distributed computer systems. The universal data compression achieves asymptotically optimum cimpression ratio for strings generated by any stationary ergodic source without a priori source probabilities.The paper describes the principle and the recent research trends on universal data compression. And its applications.
A Study on the Implementation of Direct Digital Frequency Synthesizer using the synthesized Clock Counting Method to make the State of randomly Frequency Hopping
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 914~924
It has been generally used for PLL(Phase Locked Loop) to be synthesized randomly chosen frequency state, but the PLL locking time was inevitable element. A direct digital synthesizer. Which makes output frequency directly in sine wave by a phase accumulating method, could be leiminate the defect, although a phase distortion in frequency spectrum. In order to improve this disadvantage, the phase accumulating method is reconsidered in the side of he output wave formula expression. A new mechanism is proposed, and it is constructed by a most suitable logic elements. The spectrum of synthesized sine waveform is simulated and compared with a measured value, and it’s the coherence frequency hoppong state with the PN(Pseudo Noise) code sequence is confirmed. In this results, the power levels of phase distortion harmonics are decreased to 10~25dB and bandwidths are increased to 420kHz.
Analysis and Design of the Cylindrical-rectangular Patch Microstrip Resonator
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 925~933
Caracteristics of cylindrical rectanyular patch microshtrip resonator are analyzed by cavity model. To minimize the error of resonant frequency due to fringing field, the resonant frequency is calcylated by the concept of effective dielectric constant. The transmisson type resonator operating at 3GHz is designed and manufactured. The measured data of the resonant frequency and reflection loss are 3.019Ghz and \ulcorner32.78dB respectively. These results nearly coincide with theoretical results
Optical Implementation of Single Layer Neural Networks Using Diffraction Grating
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 934~940
A modified quantizing method is introduced to teach single layer learning algorithm, which is implemented optically. The proposed optical system consists of input masks, holographic diffraction grating. LCD and CCD camera. The 2 dimensional interconnections between input neurons and output neurons are realized using holographic phase grating, which is fabricated for equal intensity distribution of diffraction orders. The two gray levels of LCD act as binary weights for each interconnection. The weights are compensated according to the learning algorithm in which the amount of weights to be compensated is determined by comparing the output patterns with target patterns. The learning process is iterated until the predetermined conditions are satisfied. Optical experiments are performed for two learning rates, 0.5 and 0.9 and the experimental results show that the proposed system is useful for optical neural networks.
A Multipath Delay Time Detection Method For
Shift QPSK Modulation Under The Frequency Selective Fading Environment
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 941~950
channel is severely degraded by multipath delay time spread. In this paper. We propose a simple multipath delay time detection method, which has a merit of in serviceable, yet simple H/W realizability for
shift QPSK by detecting cross channel interference. A
shift QPSK signal originally has quadrature channel(Q-ch) component. Thus in order to measure CCI between in-phase channel(I-ch) and quadrature channel(Q-ch), which closely related to multipath delay time, Frequency doubling scheme(frequency doubler) and differential detector is proposed, which makes
shift QPSK signal look like BPSK and also makes it possible for CCI to be detected at I-ch detector output. To get an information from time varying I-ch output signal under the multipath lading environment, a method for obtaining the mean of the absolute value
and another one for obtaining the root mean square value
of CCI are proposed. Furthermore, a relationship between delay spread and CCI is also analyzed. In order to confirm theoretical results, computer simulation has been carried out under the quasi-static and Reyleigh distributed two ray multipath fading environments. A fairly good result was obtained. However it was also shown that this method is sensitive to bandwidth restriction to some extent. In addition, some idea for a simple hardware realization for the frequency doubler are given.
A Consideration and Implementation of QPSK System for Effective Bandwidth in Digital Mobile Communication
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 951~963
In this paper M-ary Psk system for digital land mobile radio utilized the raised-cosine filter instead of LPF with rectangular frequency characteristic as luniting channel bandwidth are implemented to measure their performance and effect of ISI and jitter. Also the error probability is calcylated on the condition of fast Rayleihg fading, cochannel interference and AWGN, It is found that QPSK and 8-PSK system with 2-branch diversity, can be improved by 3 or 5 time of spectral effciency respectively, comparinng with one of the non diversity QPSK and 8.PSK system
Noise Shaping effects of Signal-blurred DPCM
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 964~971
In DPCM coder which has flat notse distributions, reconstruction noises might be shaped or transferred to hign frequency portion using the relevant noise reduction loop under the constraints of image compression. Noise shaping filter directly in loop can be used, but we shows the complete characteristics of signal blurred DPCM coder in view of data compression and noise processing. Equi weighting in bluming procedure of prefilter is introduced and the blurred signal is restored by debiurning postfilter. Noise shaping tegion on two dimensional frequency domain depends upon the size of masking filter. In spite of its noise increments by the signal blurring, the algonthm is effective for the visually relevant coding which has low pass freqency properties.
A Study on the LQG/LTR for Nonminimum Phase Plant (I) : Optimal Approximation Method
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 972~980
LQG/LTR method have a theoretical constraint that it cannot applied to nonminimum phase plant. In this paper we suggest two methods of approximation of minimum phase plant for a given nonminimum phase plant to solve this constraint. Error is described by additive form which can reduce its magnitude in broad frequency range. A optimal approximation method was suggested by using Hankel operator theory and Nehan theory it is shown by example that the methods suggested can resolve the frequency domain constraint arised in Stein and Athans approximation.
A Study on the LQG/LTR for Nonminimum Phase Plant (II) : Realization for the Optimal Approximation Method
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 981~991
LQG/LTR method suggested to improve robustness of LQG have a theoritical constraint that it cannot apply to nonminimum phase plant(NMP). In this paper, we suggest a new LQG/LTR method for NMP which consist of three design steps. The first step is design a additional feed-foward compensator which approximate the given NMP plant to minimum phase(MP) plant and the next step is design a target loop transfer function for approximated MP plant satisfying the design specifications such as robust-performance and robust-stability. The last step is loop transfor recovery(LTR) that the open loop transfer function recovers the terget loop. It was shown by simulation example that the suggested method can solve the NMP constraint in designing LQG/LTR.
A Study on the Computer Intergrated Manufacturing System Using LAN
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 992~1000
At present, using different method, in the view of point of that factory to the rising of the productivity, they try to rise productivity by factory automation. First, it is the automation of each unit process. In out country, in the case of a few developed factory. they are realized by line automation. The majority factories are established by automation device of unit process. But, as the established devices, it must be connect between unit processes or mutual assistance and offical automation in order to raise up productivity highly. In this paper, process inspection control system is installed by each unit process automation and connect main computer with them. So, we try to rise high productivity using stochastic process and supervision function.
Design of the Efficient Clock Recovery Circuit in the Communication Systems using the Manchester Encoding Scheme
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 1001~1008
.In this paper the efficient clock recovery algorithm is proposed to regenerate the manchester code at the system using the Manchester encoding scheme such as LAN. Mobile communication and digital communication systems. The proposed clock recovery circuit recovers the clock using the two times of the same original transmitted frequency can be completely recovered. The implementation of the proposed clock recovery circuit and the interpretation of test results prove the validity of the proposed algorithm.
Design and Implementation of Educational Hangul Pascal
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 1009~1018
In this paper, we present a design and inplementation of the Hangul pascal programming language corresponding to Turbo pascal. The instructions of Hangul pascal were easily seledted to be understood of elementary middle, high school syudents, and Dos commands and error messages were translated into Hangul. Hangul-pascal were implemented into C-language under IBM PC XT / AT, MS-DOS.
A method for computing a coupling coefficients between a microstripline and a dielectric resonator
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 10, 1991, Pages 1019~1025
An analytic method of computation of the coupling coefficients between a microstripline and a die-lectric resonator is showen in this paper. The relationships among the substrate material, the ground plane, the diele-lents. The theoretically computed values of Qext are compared with the experimentally measured values of Qext in there is no dieletric spacer between them, As a result, the reflection coefficients with the dielectric spacer between the dieletric resonator and the substrate are decreased more than the reflection coefficients without the didlectric spacer between them.