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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 13, Issue 6 - Dec 1988
Volume 13, Issue 5 - Oct 1988
Volume 13, Issue 4 - Aug 1988
Volume 13, Issue 3 - Jun 1988
Volume 13, Issue 2 - Apr 1988
Volume 13, Issue 1 - Feb 1988
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Timing Titter Analysis in the ISDN U-Interface
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 369~378
In this paper, the performance of the timing jitter which has great effects on the echo canceller that can be used for full-duplex digital transmission on two-wire subscriber loops is analyzed. The power spectrum of timing jitter is about 8.9dB lower in the AMI input format than in the Polar-NRZ-L input format. The performance of the echo canceller also has been shown improved by 4dB when the input signal is in the AMI format.
A Study on the Reliability Evaluation of Communication Networks by Matrix Transformation
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 379~389
In this paper, an algorithm for obtaining 2-state switching failure function and a terminal pair reliability evaluation method in a communication network are proposed. The communication network is modeled by a graph. By using the sequence of matrix transformations for the graph, minimal cut-set matrix representing all minimal cut-sets which completely interrupt the communication path is determined and 2-state switching failure function is then obtained from the minimal cut-set matrix. The terminal pari reliability of the communication network is evaluated by corresponding the random variables to 2-state switching failure function. Illustrative examples are provided to demonstrate the algorithm. A computer program evaluating the terminal pair reliability in a complex and large network has also been developed.
BTC employing a Quad Tree Technique for Image Data Compression
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 390~399
A conventional BTC has the merit of real time processing and simple computation, but has the problem that its compression rate is low. In this paper, a modified BTC using the Quad Tree which is frequently used in binary image is proposed. The method results in the low compression rate by decreasing the total number of subblocks by mean of making the size of a subblock large in the small variation area of graty level and the size af a subblock small in the large variation area of gary level. For the effective transmission of bit plane, the Huffman run-lengh code for the large size of a subblock and the lookup table for tha small size of a subblock are used. The proposed BTC method show the result of coding 256 level image at the average data rate of about 0.8 bit/pixel.
A Fast Synchronization System of DS Spread Spectrum Communication Using SAW Components
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 400~410
In this paper, a fast synchronization system using SAW TDL matched filter and SAW recirculation loop not only for acquisition but also tracking in the direct sequence spread spectrum communication receiver in case of low SNR was designed and its characteristics were investigated. When signal of 16dB SNR was inputed at the receiver, the PN code of the receiver could be synchronized from the extracted signal for synchronization through SAW TDL matched filter and SAM recirculation loop for 30 recirculations. And the average synchronization time of this system was calculated. From the results, we found that this synchronization system could achieve faster synchronization of PN codes in the receiver under the circumstances of low SNR than that of using only matched filter.
Tabular Methods for the Design of Multivalued Logic Circuits Using CCD
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 411~421
This paper offers a method to design CCD four-valued circuits using the tabular method. First, the four-valued logic function is decomposed by hand-calculation or computer program. Nest, the algorithm is derived form the tabular method based on the decomposition process to realize the DDC four-valued circuit. According to this algorithm, the two-variable four valued logic function is decomposed and realized by CCD network with four basic gates. The synthesis method in this paper proves that the number of devices and cost is considerably reduces as compared with the existing methods to realize the same logic functions.
A Design Method of Discrete Time Learning Control System
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 422~428
An iterative learning control system is a control system which makes system outputs follow desired outputs by iterating its trials over a finite time interval. In a discrete time system, we proposed one method in which present control inputs can be obtained by a linear combination of the input sequence and time-shifted error sequence at previous trial. In contrast with a continous time learning control system which needs differential opreration of an error signal, the time shift operation of the error sequence is simpler in a computer control system and its effectiveness is shown by a simulation.
A Bit-serial Encoder of (255, 223) Reed-Solomon code
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 429~436
This paper presents a method of designing a Bit-Serial Reed-Solomon encoder using Berlekamp's Bit-Serial Multiplier Algorithm and the implementation of the (255, 223) Bit-Serial Reed-Solomon encoder using TTL logics. It is shown from these results that this encoder require substanitially less hardware than the convenional Reed-Solomon encoders.
Scattering Characteristics of The Infinite Strip Conductor for TM Waves
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 437~443
We calculate the distribution of the current on the strip by the incident waves on the infinite conducting strip line. The boundary equations represented as the spatial domain function become very complicated equations including convolution integral. Transformed it to the spectral domain, we have a very simple equation is composed by some algebraic multiplication of the current density function and Green's function. the acceleration of iteration procedure is achieved by Kastner's method. The result of iteration gives us the optimum value when it satisfies the iteration stop condition presented in this paper. We confirmed that the induced current density distribution on the stripline has been changed as variaties of the width.
A Study on the Log-periodic Loop Antenna with the Parasitic Elements
The Journal of Korean Institute of Communications and Information Sciences, volume 13, issue 5, 1988, Pages 444~452
The LP(Log-periodic) type antenna composed of the cross fed and parasitic loop elements has been proposed for a high gain and broadband characteristics. This antenna has been analyzed by using moment method, and current distribution, input impedence, power gain, and radiation patterns has been calculated and compared with LPDA. It was found to have high gain, broadband characteristics, and similiar patterns for E and H plane against LPDA.