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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
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Journal DOI :
The Korean Institute of Communications and Information Sciences
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Volume & Issues
Volume 11, Issue 6 - Dec 1986
Volume 11, Issue 5 - Oct 1986
Volume 11, Issue 4 - Aug 1986
Volume 11, Issue 3 - Jun 1986
Volume 11, Issue 2 - Apr 1986
Volume 11, Issue 1 - Feb 1986
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Ultra-High-Speed Semiconductor Devices for Data Communication Applications -Digital GaAs IC'S and HEMT'S-
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 153~163
GaAs, one of the III-V compounding semicondnctors, has been widely employed as base materials for the fabrication of the ultra-high-speed devices in the filelds of DBS, optical communications, MMIC'S and digital IC'S. There have been some reports on 4Kx4bit SRAM by D/E MESFET'S, 4K bit SRAM by HEMT'S, and receiver front ends for X-band by MMIC technologies, respectively. This paper reviews GaAs materials, wafer fabrication processes, device applications, and design aspects, and, finally, descusses the future of the ultra-high-spped-devices.
Design Philosopy for Workstation
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 164~171
In this paper the design philosphy for workstation is presented. In order to increase the productivity of input and output, the workstation needs to have a short response time and a powerful display function. And it would be preferable that the workstation should be designed to share the resources and to have a highly portable and user-friendly software structure.
Design of Programmable SC Filter
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 172~178
The recent interest in the design of filters is motivatied by the fact that such filter can be fully integrated using standard metal-oxide-semiconductor processing technology. This is due to replacing all the resistors in the active RC filter network by the switched capacitors. The voltage gain of a SC filter depends only on the rations of capacitance and these ratios can be obtained and maintained to high accuracy. Therefore, it is known that a switched capacitor is much better than a resistor in temperature and linearity characteristics. This paper proposed a programmable SC filter and proved the fact that
Q and G of this circuit can be controlled by digital signal. Experiments show that SC filter remains the low sensitivities but it can't avoid little influence of parasitic capacitance. As the transfer characteristic of the SC filter is varied with sampling frequency and resistor array, SC filtering technigue can be applied for digital processing, speech analysis and synthesis and so on.
Performance Analysis of a Statistical Packet Voice/Data Multiplexer
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 179~196
In this paper, the peformance of a statistical packet voice/data multiplexer is studied. In ths study we assume that in the packet voice/data multiplexer two separate finite queues are used for voice and data traffics, and that voice traffic gets priority over data. For the performance analysis we divide the output link of the multiplexer into a sequence of time slots. The voice signal is modeled as an (M+1) - state Markov process, M being the packet generation period in slots. As for the data traffic, it is modeled by a simple Poisson process. In our discrete time domain analysis, the queueing behavior of voice traffic is little affected by the data traffic since voice signal has priority over data. Therefore, we first analyze the queueing behavior of voice traffic, and then using the result, we study the queueing behavior of data traffic. For the packet voice multiplexer, both inpur state and voice buffer occupancy are formulated by a two-dimensional Markov chain. For the integrated voice/data multiplexer we use a three-dimensional Markov chain that represents the input voice state and the buffer occupancies of voice and data. With these models, the numerical results for the performance have been obtained by the Gauss-Seidel iteration method. The analytical results have been verified by computer simylation. From the results we have found that there exist tradeoffs among the number of voice users, output link capacity, voic queue size and overflow probability for the voice traffic, and also exist tradeoffs among traffic load, data queue size and oveflow probability for the data traffic. Also, there exists a tradeoff between the performance of voice and data traffics for given inpur traffics and link capacity. In addition, it has been found that the average queueing delay of data traffic is longer than the maximum buffer size, when the gain of time assignment speech interpolation(TASI) is more than two and the number of voice users is small.
A Study on Transform Coding of Image Signal using Microcomputer
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 197~203
The images which are scanned by CCTV are converted to digital signal and 6502 Microcomputer processes data by Transform coding. Thus data is reduced to
pixels and input by outer memory using same address with inner one for the fast process. Hadmard Transform, Weighted Hadamard Transform which is weighted in the center of matrix and Haar Transform are programmed by assembly language and every Transform is dome within one second.
A Study on the Frequency-Output Power Stabilization of Semicondutor Laser for Heterodyne Optical Communication Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 204~210
In this paper, a new method is suggested to stabilize the frequency of semiconductor laser diode for heterodyne optical communication systems. In order to stabilize the frequency of semiconductor laser, the method of the injection current controal has been widely used, in which the laser frequency is locked to a F-P interferometer. By adding another servoloop to stabilize the output power of semiconductor laser, we could stabilize the laser frequency and the output power simultaneously and the frequency stability is improved by a factor of fice times.
Experiment on the CW Interference Rejection in a Wide-band Communication System
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 211~216
This paper presents theoretical analysis and experimental results on an improved interference rejection circuit in the presence of continuous wave interference at center frequency, particularly in a wide-band communication systems. This circuit is based upon a phase locked loop for estimating the CW interference phase and the MSE technique to minimize the estimation error. Therefore, the introduced rejection circuit that minimized the estimated phase error outperforms the rejection circuit with phase estimation only. As a result of experiment, we confirm that this proposed rejection circuit gives a high degree of interference rejection performances when the input J/S is large.
Multi-Channel FIR Digital Filter Hardware Implementation using DQSM Algorithm
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 3, 1986, Pages 217~226
A method on the hardware implementation of the Multi-channel FIR digital filter using Digital Quarter Square Multiplication(DQSM) algorithm is proposed. This paper describes that ROM requirement can be reduced by using the double precision algorithm and the absolute value circuit, and also execution speed can be improved by reducing logic level steps of absolute value circuit. The frequency response of the four channel FIR digital filter implemented by the above method is quite agreeable with the frequency response simulated by Remez excahange algorithm.