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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
The Journal of Korean Institute of Communications and Information Sciences
Journal Basic Information
Journal DOI :
The Korean Institute of Communications and Information Sciences
Editor in Chief :
Kyung-Hi Chang / Song Chong / Jong-Taek Oh / Jae-Jin Lee / Myung-Sik Yoo
Volume & Issues
Volume 14, Issue 6 - Dec 1989
Volume 14, Issue 5 - Oct 1989
Volume 14, Issue 4 - Aug 1989
Volume 14, Issue 3 - Jun 1989
Volume 14, Issue 2 - Apr 1989
Volume 14, Issue 1 - Feb 1989
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Models and Charcteristics of Multipath Propagation on Mobile Radio in an Urban Area
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 293~306
In this paper, the models and characteristics of multipath propagation in an urban environment are described. Three propagation models(a random model, a ray model and a method of estimating time delay is proposed based on the envelope correlation between two radio frequencies. It is shown on the basis of laboratory simulation and field tests that the simple two-ray model is an adequate model for the fundamental study of the multipath propagation characteristic of the mobile radiowave and the estimating time delays of multipath-propagated waves in an urban area.
Fabrication of Optical Fiber Preform by MCVD Method
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 307~320
This paper presetns new design of the Modified Chemical Vapor Deposition(MCVD) system for optical fiber preform fabrication. It contains a glass working lathe, raw material supplier and exhaust gas treatment apparatus as fundamental instruments for MCVD process, graded index fiber design, characteristic of process and the experimenta arrangement to measure the refractive index profile of MCVD preforms, respectively. From the investigation results, it is shown that an ideal graded index fiber preform does not exhibit a center dip or bump.
Finite-Element Method Analysis in Eigenmode of Microwave and Optical Waveguides
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 321~328
The propagation characteristics of dielectric waveguides has been analyzed by finite element method. We have proposed the finite element formutation of the variational expression in the three-component magnetic field based on Galerkin's method which seek for the propagation constant by a given value of frequency. In this approach, the divergence relation for H is satisfied and spurious modes does not appear and finite element solustions agree with the exact solutions. In order to varify the validity of the present method the numerical results for a rectangular waveguide partilly filled with dielectric are compared with other results.
A Study on the Composition of Large Capacity Time Switch by Multi-write Method
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 329~337
This paper describes a composition of time switch with a large capacity(NK byte) by multi-write method. The method arranged a basic unit in a plane and a group, which is composed by 1K byte time switch using a memory elements with a fixed access time and capacity. And the time switch of large capacity is composed by multi-write method, which is more than 8K byte capacity with many constraints by using today's semiconductor development techniques, then a basic unit is the 1K byte time switch using a CMOS SRAM with 62.5ns access time and 1K byte capacity.
A Study on the Implementation and Performance Analysis of the Digital Frequency Synthesizer Using the Clock Counting Method
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 338~347
In this paper, the digital frequency synthesizer with the clock ccunting method is designed and implemented to increase the performace of the digital frequency synthesizer with pahse accumulating method which was developed before. Unlike an phase accumulating method, clock countind method is supplied a continually changeable clock frequency with PLL(Phase Locked Loop) and allocated a fixed phase step with N-ary counter. Form the experimenta results, it is confirmed that any periodic distorition phenomena are disappeared, and truncation harmonics are more reduced. But the output bandwidths are decreased in inverse proportion to the counter counting number and the circuits are somewhat complex than phase accumulating method.
A Study on the Improvement of Multitree Pattern Recognition Algorithm
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 348~359
The multitree pattern recognition algorithm proposed by  and  is modified in order to improve its performance. The basic idea of the multitree pattern classification algorithm is that the binary dceision tree used to classify an unknow pattern is constructed for each feature and that at each stage, classification rule decides whether to classify the unknown pattern or to extract the feature value according to the feature ordet. So the feature ordering needed in the calssification procedure is simple and the number of features used in the classification procedure is small compared with other classification algorithms. Thus the algorithm can be easily applied to real pattern recognition problems even when the number of features and that of the classes are very large. In this paper, the wighting factor assignment scheme in the decision procedure is modified and various classification rules are proposed by means of the weighting factor. And the branch and bound method is applied to feature subset selection and feature ordering. Several experimental results show that the performance of the multitree pattern classification algorithm is improved by the proposed scheme.
Performance Analsis of an Integranted Voice/Data Cut-Through Switching Network
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 360~368
In this paper, the performance of an integrated voice/data cut-through switching network is studied. We first derive cut-through probabilities of voice and data packets at intermediate nodes. Then, the Laplace transform for the network delay is obtained. According to numerical results, the performance of cut-through switching is superior to that of packet switching for integrated voice/data networks.
A Study on Average Access Times by Priority Levels of FDDI MAC Protocol
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 369~373
This paper investigates average access times on eight asynchronous priority levels of FDDI MAC protocol with parameters on offered loads, message sizes, and number of stations. In case of parameter with offered loads, higher priority levels exhibit similar variances and in case of parameter with message sizes and number of satations, higher priority levels exhibit almost invariables but as increase of message sizes, increase only a small amount of access time on the other hand, as number of stations increase, average access times decrease little by little. But in case of lowest priority level. average access times decrease little by little. But in case of lowest priority level, average access times exhibit relatively large variances about above three parameters.
The Decoding Algorithm of Binary BCH Codes using Symmetric Matrix
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 374~387
The decoding method of Binary BCH Codes using symmetric matrix is proposed in this paper. With this method, the error-locator-polynomial is composed by symmetric matrix which consists of the powers of the unknown X plus the synfromes as its elements. The symmetric matirx can also be represented in terms of the unknown X. But the each coefficients of the error-locator polynomial represents the matirx with the syndromes as its entries. By utilizing this proposed algorithm, the device for decoding circuit of the (63, 45) BCH Code for t=3 has been implemented for demonstration.
An Efficient Parallel Algorithm for Solving Large Sparse Linear Systems of Equations
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 388~397
This paper describes an intelligent iterative parallel algorithm for solving large sparse linear systems of equations, and proposes a ststic dataflow computer architechture for the implementation of the algorithm. Implemented with the Jacobi interative method, the intelligent algorithm reduces the parallel execution time by reducing the individual inner product operation time.
Optical Pattern Recognition System using a
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 398~404
Optical pattern recognition system using real-time hologram mechanism in a photorefractive $BaTiO_2$ single crystal is analyzed and experimented. Edge enhancement technique is introduced for enhancing pattern discrimination capability, and patterns can be recognized within 8 sec with 5.5mW low incident light intensity.
Performance Evaluation and Modification of LCTV for Spatial Light Modulator
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 405~411
Performance evaluation of inexpensive LCTV to function as a two-dimensional spatial light modulator is performed. Correction of the phase distortion of the device is performed using the substrate of hologram plate and index matching oil. A new method for eliminating electrode grid pattern that incorporates phase conjugation in a BaTiO3 crystal is proposed and experimented.
A Study on the Conversion Algorithm and its Implementation Technique Between NAS and CEPT Channel Associated Signalling
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 412~422
The need to conversion between NAS and CEPT networks has led to the development of PCM standards conversion techniques, especially signalling conversion techniques. This paper contains a brief description and general overview of channel associated signalling(CAS) of 24-channel system and of 30-channel system. The line signalling conversion algorithm between two systems and the transition detection algorithm of call status is proposed. And this paper presents the effective inplementation techniques of these algorithm.
Design of Digital Transmultiplexing System for PRS Transmission
The Journal of Korean Institute of Communications and Information Sciences, volume 14, issue 4, 1989, Pages 423~434
In this paper, a PRS transmission system using TMRCP as the unit pulse is proposed, which solves the problems occur when the PRS method will be applied to the digital transmultiplexer for each channel. And a design technique which uses this PRS method for the FFT polyphase filter transmultiplexer concept is given. TMRCP-PRS signal require a bandwidth about 2.5KHz(including some guard-band) for a 4-KHz bandlimited voice channel. Therefore, in he 24 channel transmission line, it gives the same advantages as he ordinary PRS system and sloves the inter-channel interference problems. And its good speed-tolerance reduces the time-errors by the environments and the power loss, so it makes the system to be stable. The total system, however, attaces the filters for PCM-PRS, PRS-PCM conversion before and after the transmultiplexer respectively.