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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 18, Issue 12 - Dec 1993
Volume 18, Issue 11 - Nov 1993
Volume 18, Issue 10 - Oct 1993
Volume 18, Issue 9 - Sep 1993
Volume 18, Issue 8 - Aug 1993
Volume 18, Issue 7 - Jul 1993
Volume 18, Issue 6 - Jun 1993
Volume 18, Issue 5 - May 1993
Volume 18, Issue 4 - Apr 1993
Volume 18, Issue 3 - Mar 1993
Volume 18, Issue 2 - Feb 1993
Volume 18, Issue 1 - Jan 1993
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A Recognition of Handwritten English Characters Using Back Propagation Algorithm and Dictionary
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 157~168
In this paper, it is shown that neural networks trained with back propagation algorithm and dictionary can be applied to recognize handwritten English characters. To eliminate the useless data part and to minimize the variety of characters from the scanned image file, various preprocessings : that is, segmentation, centering, noise filtering, sealing and thinning are performed. After these, characteristic features are derived from thinned character pattern. The neural network is trained by using the extracted features for sample data, and all test data are classified into English alphabets according to their features through the neural network. Finally, the ways of reducing learning time and improving recognition rate, and the relationship between learning time and hidden layer nodes are considered. As a result of this study, after successful training, a high recognition rate has been obtained with this system for the trained patterns and about 93% for test patterns. Using dictionary, the recognition rate was about 97% for test pattern.
Modelling and Validation of AX.25 Protocol for Microsatellite Packet Communications
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 169~177
In this paper an experimental microsatellite packet radio protocol based on the terrestrial AX.25 amateur packet radio protocol is introduced and its protocol is modeled by the extended Petri Nets with timers and counters. Finally, this protocol is validated in terms of correctness, recovery, boundness, deadlock, etc by its reachability tree.
Optimal Range of the Step Size in LMS Adative Algorithm
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 178~183
This paper presents a new optimal range of the step size to converge LMS adaptive algorithm considering quantization error of equalizer coefficient and excess MSE. And the simulation of transversal equalizer shows the propriety of it.
The Design of Continuous-Time MOSFET-C Filter
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 184~191
Continuous-time integrated filters, implemented in MOS VLSI technology, have been receiving considerable attention. In this paper, a continuous-time fifth order elliptic low-pass MOSFET-C filter has been designed with a cutoff frequency 3,400Hz. First an active RC filter is designed using cascade method which each block can be tunable. And then the resistors of an active RC network are replaced by a linear resistor using NMOS depletion transistors operated in the triode region. This continuous-time MOSFET filter have simpler structure than switched-capacitor filter, so reduce the chip area. The designed MOSFET-C filter characteristics are simulated by PSPICE program.
On the Implementation of Model System for Speech Transmission Quality Evaluation of Digital Communication Network
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 192~201
According to technical advances of telecommunication, communication network has changed to digital transmission from analog transmission network. In the long run, current network will be altered into ISDN which makes end-to-end digital communication. This transition of communication network brings about an important questions for networking plan, administration, and speech quality in order to achieve the effective and advanced telecommunication. Speech quality criterions and degradation factors of digital communication system differ from those of existing analog system because of other characteristics like single echo. It is, therefore, necessary to design new criterions and specifications for digital communication network. This Paper describes the relation between speech communication and speech transmission quality and describes the implementation of model system for quality evaluation of digital speech communication network. In addition, some applications of model system implemented are proposed.
A Study on the Problems on ISDN Implementation Caused by the Conversion of Transmission System into Duropean Style in Korea
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 202~206
To secure the 64 kbps clear channel capability in the ISDN, it was decided to convert its North American digital transmission system into the European system especially in DS1 level. But their different companding law became an issue in the process of R&D in the existing time division digital switch such as TDX-1 to incorporate it into the ISDN. TDX-1 has been installed with North American
companding law and its ISDN capability is under development now. Thus, because of the
law/A law conversion for the interworking of two different transmission system, it is difficult to maintain the ISDN B channel transparency between TDX-1 and new European system with A companding law. Among some solutions for it, European frame format with
law companding is recommended. Those problems and solutions are presented in this paper.
Acquisition of Direct-Sequence Cellular Communication System for Code Division Mutlipie Access
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 207~217
In this paper, knowing a priori probability of phase offset between transmitted codes and reference codes in the receiver, we construct the state diagram of acquisition process of the direct sequence spread-spectrum communication system using the expanding window search. The scannings are performed from the cell with higher probability code epoch synchronization to that with lower one. We expand window size from initial value by r times of its previous size in each search, construct the corresponding the state diagrams, and derive average synchronization time using the Markov process and Mason's gain formula. Average synchronization times versus number of search n and detection probability
Implementation of Power Line Modem Using a Direct Sequence Spread Spectrum Technique
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 218~230
A power line modem(PLM) which transfers data safely through power lines in houses or small offices is considered. When a power line is used for communications, transmitted signals could be affected by the channel characteristics such as frequency-selective fading, interference, and time-varying attenuation. In order to overcome these impairments, a direct sequence(DS) technique which is well known as an effective instrument against a variety of interferences and hostile channel properties is employed. Using a DS technique, however, requires more circuits such as PN code generator circuits, code modification circuits, and complicated synchronization circuits, and it also results in substantial acquisition delay. In this paper, some of these circuits are implemented via software programmed in the system controller, and the complicated synchronization circuits are replaced by simple circuits utilizing a 60 Hz power signal for synchronization. The synchronization ciruits used in this paper virtually eliminate the substantial acquisition delay, and is also designed to free influence of 60 Hz zero crossing jitters which reside in a power signal. As a result, a PLM using a DS technique is realized in the form of wall-socket plug, and the PLM hardware would be very much simplified.
A Study on Reasoning and Learning of Fuzzy Rules Using Neural Networks
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 231~238
A rules of fuzzy control is to represent an expert‘s and engineer‘s ambiguous control knowledge of system with some lingustic rules. This rule is very difficult to represent perfectly because expert‘s knowledge is not precise and the rule is not perfect. We propose the fuzzy reasoning and learning to upgrade precision of imperfect rules successively after system running. In the proposed method, the precision of the backward part of a fuzzy rule is improved by back propagation learning method. Also, the method reasons the compatibility degree of the forward part of fuzzy rule by associative memory method. This method this is successfully applied to design auto-parking fuzzy controller in which expert‘s technology and knowledge are required in the limited area.
Design and Implementation of Preprocessor for Educational Hangul C Programming Language
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 239~249
In this paper, we present a design and implementation of Hangul C Programming language corresponding to Turbo C. The instruction of Hangul C were selected to be easily understood by elementary middle, high school students, and DOS commands and error message were translated into the Hangul.
A Study on the Voice/Data Integrated PRMA Protocol With the Minimum Reservation Slot Assured
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 250~260
Packet Reservation Multiple Access(PRMA) protocol provides a very efficient mechanism for many number of voice and data terminals with bursty traffic characteristics to share efficiently a common transmission channel. This protocol, however, cannot operate in high load conditions. That is, there occurs a instability problem, since the reservation channel is allowed to shrink to zero. In this paper, a more stable PRMA protocol which can avoid such problems and integrates voice and data traffic efficiently is proposed. Also, the performance of the proposed protocol is analyzed by a computer simulation. According to the simulation results, it can be shown that the proposed protocol provides a more efficient mechanism for voice/data integration and ensures a more stable operation than conventional PRMA protocol in high load conditions.
A Study on the Composite Code Sequence for CDMA Communication systems
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 261~269
Segmentation of the Korean speech signals into phonetic units using the super resolution pitch determination
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 270~278
This paper is presented the phonetic segmentation alg9rithm of the Korean speech signals which is finded the exact pitch using the super resoluton pitch determination and is compared corss-correlation to threshold each pitch period. The features of the proposed algorithm are infinite resolution and high reliability, and also can separate transient or silent segment. The algorithm is instrumental to speech processing applications which require vector quantization and speech recognition. The presented algorithm is implemented by 386-MATLAB on PC 386/DX and is verified the exact pitch period and the phonetic segmentation of speech signals.
A Study on the Dynamic Priority Scheduling for Multiple Class Traffic in ATM Network
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 279~287
In this paper, double laxity threshold MLT(Minimum Laxity Threshold) algorithm and double queue threshold QLT(Queue Length Threshold) algorithm are proposed as DPS(Dynamic Priority Scheduling) techniques for advanced processing of multiple class traffics. Also, the performance of the proposed algorithms is analyzed by a computer simulation. According to the simulation results, it can be shown that the proposed double laxity threshold ML T algorithm advances the processing performance versus ML T algorithm for 2 or more classes delay sensitive traffics, and that double queue length threshold QL T algorithm provides more efficient performance than QL T for 2 or more classes of non real time traffics.
Design of Pipeline Bus and the Performance Evaluation in Multiprocessor System
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 2, 1993, Pages 288~299
This paper proposes the new bus protocol in the tightly coupled multiprocessor system. The bus protocol uses the pipelined data transfer and block transfer scheme to increase the bus bandwidth, The bus also has the independent transfer lines for the address and data respectively, and it can transfer the data up to maximum 264 Mbytes /sec. This paper also models the multiprocessor system where each processor boards have the private cache. Simulation evaluates the bus and system performance according to hit ratio of the reference data in cache memory, In the case of using this bus, the bus is evaluated not to be saturated when up to 10 processor boards are connected to the bus. As for up to 4 memory interleavng, the performance increases linearly.