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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
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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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Performance Analysis of an Integrated Voice/Data Packet Communication Network with Window Flow Control
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 227~236
In this paper, an integrated voice/data packet network with window flow control is modeled by a colsed multichain queueing system, and its performance is analyzed by the mean value analysis method. Particularly, for the analysis of a packet network having various kinds of messages with different priority classes, we introduce an approach based on the mean value analysis and the concept of effective capacity. By the mathematical analysis and computer simulation, we obtain the following network statistics in the steady state: Mean buffer occupancy at each node, utilization of link throughput of a virtual channel, and mean delay time of each message. Our iterative analysis method can predict the link data status in most cases within about 10 percent of accurady, and the statistics of voice messages and external data within 5 percent as compared to simulation results.
The Characteristics of Current Distribution on a Spiral Scatterer
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 241~250
Current distributions are the basis of analyzing and designing the antenna. In this paper, a method of deriving the current distribution of a spiral shaped thin wire scattere is proposed when plane wave is incident on it. The calculated results are also shown for severla spiral sizes and incidence angles selected. For numerical calculation, the method of point matching is used with a cubic B-spline function as a basis function.
A Study on Image Data Compression by using Hadamard Transform
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 251~258
There is much redundancy in image data such as TV signals and many techniques to redice it have been studied. In this paper, Hadamard transform is studied through computer simulation and experimental model. Each element of hadamard matrix is either +1 or -1, and the row vectors are orthogonal to another. Its hardware implementation is the simplest of the usual orthogonal transforms because addition and sulbraction are necessary to calculate transformed signals, while not only addition but multiplication are necessary in digital Fourier transform, etc. Linclon data (64
64) are simulated using 8th-order and 16th-order Hadamard transform, and 8th-order is implemented to hardware. Theoretical calculation and experimental result of 8th-order show that 2.0 bits/sample are required for good quality.
A Study on the Design of Microwave Solid-State Oscillators
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 259~267
The small-signal S-parameters of GaAs MESFET are measured in terms of frequencies and bias conditions. The resonating network and the load matching network of the fixed-frequency microwave oscillator analyzed by two-port network analysis are designed by the optimum method of CAD. The 6GHz oscillator circuit is built and tested on the microstrip substrates. Finally, it is verified that the experimenta results conformed to the optimum data by CAD.
A Study on the Multiplexing of ISDN D-channel using Statistical Multiplexer
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 268~279
Recently, the improtance of the ISDN has been emphasized for the new services in the future information society. In this paper, new application of statistical multiplexer which can be used for CCITT D-channel multiplexing is suggested. The basic architecture of statistical multiplexer which can interleave eleven 16Kbps D-channels into one 64Kbps B-channel is also proposed. The necessary buffer size was estimated by computer simulation considering data traffic intensity, signal arrival length distribution and buffer overflow probability. Based on this buffer size, the basic architecture of the statistical multiplexer has been survetyed and hardware design principles are also studied.
Fast Mask Operators for the edge Detection in Vision System
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 280~286
A newmethod of fast mask operators for edge detection is proposed, which is based on the matrix factorization. The output of each component in the multi-directional mask operator is obtained adding every image pixels in the mask area weighting by corresponding mask element. Therefore, it is same as the result of matrix-vector multiplication like one dimensional transform, i, e, , trasnform of an image vector surrounded by mask with a transform matrix consisted of all the elements of eack mask row by row. In this paper, for the Sobel and Prewitt operators, we find the transform matrices, add up the number of operations factoring these matrices and compare the performances of the proposed method and the standard method. As a result, the number of operations with the proposed method, for Sobel and prewitt operators, without any extra storage element, are reduced by 42.85% and 50% of the standard operations, respectively and in case of an image having 100x100 pixels, the proposed Sobel operator with 301 extra storage locations can be computed by 35.93% of the standard method.
A Study on the Robustness of a 16Kbps SBC over the Rayleigh fading Channel Error
The Journal of Korean Institute of Communications and Information Sciences, volume 11, issue 4, 1986, Pages 287~295
In this paper, a SBC(sub-band-coding) is proposed to code a speech signal for a digital mobile radio and a robustness of speech quality of the SBC over the Rayleigh fading channel is investigated via a computer simulation. First the Rayleigh fading channel and 16-ary DPSK receiver models are presentes and verified its validitties by comparing with theoretical values. Three different measures: SNR, LPC distance measure and subjective listening test, were used to evaluate the effects due to the Rayleigh fading channel errors. From the results of computer simulation at BER=
, it was found that the speech remained quite intelligible at BER=
and the link is still usuable even at BER=5
Thus it was concluded that the SBC can be applicable to the digital mobile radio on the Rayleigh fading channel error in the range of
without emplowing any error correction codes.