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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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Impact of Four Wave Mixing on Manchester Coded ASK Multichannel Optical Communication System
Lee, Ho-Joon ; Leonid G. Kazovsky ;
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1607~1617
The performance of Manchester-coded ASK optical wavelength division multiplexing(WDM) systems is evaluated laking into account the shot noise and the four wave mixing(FWM) caused by fiber nonlinearities. The result is compared to conventional non-return-to-zero(NRZ) systems for ASK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power(limited by the FWM), to the minimum input power(limited by receiver sensitivity), is evaluated. For 1.55 rm 16 channel WDM systems, the dynamic range of ASK Manchester coded systems shows a 2.0 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.
Optimum Bit Allocation for Lossless Laplacian Pyramid Coding
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1618~1625
In the transmission of image using the lossless Laplacian pyramid coding, the image quality of the last hierachy is almost same regardless of the bit rate of each hierachy. However, at the higher hierachy with low resolution, it is varied according to bit rate of each hierachy. In this paper, optimum bit allocation to achieve better image at the higher hierachy and minimize the distortion at the last hierachy was proposed. More efficient progressive transmission was shown to be possible by experimental results of higher PSNR and better image quality at the hierachy with low resolution.
On the Design of a DCT Transmission Method using Channel Optimized Quantizer Combined with Error Correcting Codes
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1626~1634
In this paper we propose a coding scheme which combines source codes and error correcting codes in order to be robus to channel noise. One of the coding schemes that take into account both the source and the channel is the channel optimized quantizer (COQ) which simultaneously minimizes quantization noise and the noise due to channel errors. This paper deals with the problem of combining channel optimized quantizers with ECC to build an improved system. To be specific, we computed the performance of an n bit COQ and that of an n-1 bit COQ followed by an (n-1)/n punctured convolutional code. From this result whether or not the ECC are selected is determined by the number of allocated bits and the channel bit error rate. These results are applied to the image trans-mission method using DCT, and the system performances are evaluated.
A Statistical Analysis of Edge Enhancing Filters and Their Effects on Edge Detection
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1635~1644
In this paper, we examine the statistical characteristics of edge enhancing filters and their efficacy as preprocessing operator before edge detection. In particular, edge enhancing filters called the Comparison and Selection(CS), Hachimura-kuwahara(HK), and Selective Average(SA) filters are considered. These filters can reduce noise while producing step-type edges, thus seem to be effective for preprocessing noisy images prior to applying edge detecors. The ability of edge enhancing filters to suppress white Gaussian noise and the error probabilities occured during the edge detection following SA prefiltering are evaluated statistically through numerical analysis. The effect of prefiltering on edge detection is assessed by applying the edge enhancing fitters to a noise image degraded by additive white noise prior to applying the Sobel operator and the Laplacian of Gaussian( LoG ) operator, respectively. It is shown that the edge enhancing filters tend to produce ideal step-type edges while reducing the noise reasonably well, and the use of edge enhancing filters prior to edge detection can improve the performance of subsequent edge detector.
Temporal Filter for Image Data Compression
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1645~1654
Unlike a noise removal recursive temporal filter, this paper presents a temporal filter which improves visual quality and data compression efficiency. In general, for the temporal band-limitation, temporal aliasing should be considered. Since most of a video signal has temporally aliased components, it is desirable to consider them. From a signal processing point of view, it is impossible to realize the filtering not afeced by the aliasings. However, in this paper, efficient filtering with de-aliasing characteristics is proposed. Considering the location of a video signal, temporal filtering can be accomplished by the spatial filtering along the motion vector trajectory (Motion Adaptive Spatial Filter). This filtered result dose not include the aliasings. Besides the efficient band-limitation, temporal noise is also reduced. For the evaluation of the MASF, its realization and filtering characteristics will be discussed in ditail.
Comparison of Parallel CRC Verification Algorithms for ATM Cell Delineation
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1655~1662
In this paper we discuss three algorithms-Direct, Successive, and Recursive-on parallel CRC(Cyclic Redundancy Check) verification. The algorithms are derived by combining the byte-syndromes precomputed from the generator polynomial. These algorithms are compared in terms of the amount of hardware and the speed of operation. Since the algorithms can be generalized easily, we took the ATM cell delineation example for easier description. As an application of the algorithm Recursive, an ATM cell delineation module suitable for STM-1 transmission has been successfully realized through commercially available field programmable gate arrays.
Design and implementation of a contiguous-band diplexer using asymmetrical coupled microstrip lines
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1663~1668
An X-band contiguous band diplexer is realized by using asymmetrical coupled microstrip lines. The design is based on the singly terminated low pass prototype filter and optimized by using SuperCompack. The designed channel 1 and channel 2 bandwidth is 22%, and 18% respectively, where the center frequency is 9,11 GHz. The measured results of the fabricated diplexer are in good agreement with the designed ones, but the measured insertion loss is slightly highier(0.5dB) than those of the designed value.
A analysis of Thin-Straight Monopole antenna on a conducting box Using the Wire-Grid Method
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1669~1676
In this paper, a thin-straight monopole antenna attached to a conducting box is analyzed using a moment method with the pocklington integral expression for the exact Green's function. A modeling of a conducting box is based on a Wire-Grid method for an efficient calculation procedure. A system of linear equation is obtained using the piecewise sinusoidal basis function. And a Junction basis function is enforcing to represent the physical current on the edge of the conducting box. Especially, the junction basis functions are overlapped for the current continuity preserving on the vertexes. Numerical results are obtained for the current distribution on the unified antenna/conducting box system, input impedance and radiation pattern. The results are compared with the known data.
A Study on Optimization of Speech Encryption Scheme using Hopping Filter in order to Solve the Synchronization Problem
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1677~1688
Two dimensional amplitude scrambling algorithm using the hopping filter, which improve the drawback of conventional speech encryption scheme, is powerful encryption scheme in analog sppech signal. In this paper, we proposed the variable delay weight algorithm using hopping filter in order to solve the synchronization problem of two dimensional amplitude scrambling. Futhermore, analyzing the distortion of received signal which is transmitted in the gaussian noise channel, we determined the optimal encryption algorithm and optimal SNR using the simulation.
) ShuffleNet: An Improved Virtual Topology for WDM Multi-Hop Broadband Switches
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1689~1700
WDM(Wavelength Division Multiplexing) based-on fixed wavelengths is a new means of utilizing the bandwidth of optical fibers. In this Paper, an improved virtual topology called "(a,
) ShuffleNet " is introdced for designing large-scale WDM switches. The proposed one is an architecture created by vertically stacking x planes of a (
) ShuffleNet in parallel via
r nodes called "bridge nodes" so that N-by-N(N=(x*
) switching is achieved based on the self-routing algorithm for each (
) ShuffleNet. With the topological parallelism, in contrast to the conventional virtual topologies, the diameter of 2
hops can be fixed and high utilization and performance are provided while N increases. Such a scalability characteristic allows to design a growable broadband switch. As for the delay, we show that the traffic locality, due to the topological feature. result in low delay characteristics.lay characteristics.
A Study on the RACMC Algorithm for the Efficient Management of ATM Network Resources
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1701~1713
This paper proposes a simple and highly effective RACMC(Real-time ATM Cell Monitoring and Control) algorithm and the resulting bandwidth gain effects art considered. RACMC algorithm performs usage parameter controls according to the monitoring informations of input data cells generated from the accepted connections and the controlling informations set by the M/P(Management Plane) for that connection. The results of monitoring and controlling actions for ATM data cells are transmitted to the M/P and the control parameters in lookup table are updated according to the condition of currently used bandwith. Therefore, the proposed algorithm can allocate network resource optimally and solve the several tantalizing problems that the existing cell control algorithm have, that is, the difficulty in controlling as monitoring very bursty traffics, unavoidable processing delay, and limited input buffer size when implemented. By the performance analysis using computer simulation, RACMC algorithm proves to be very effective especially in ATM network as implemented simply.
The Cubically Filtered Gradient Algorithm and Structure for Efficient Adaptive Filter Design
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1714~1725
This paper analyzes the properties of such algorithm that corresponds to the nonlinear adaptive algorithm with additional update terms, parameterized by the scalar factors a1, a2, a3 and Presents its structure. The analysis of convergence leads to eigenvalues of the transition matrix for the mean weight vector. Regions in which the algorithm becomes stable are demonstrated. The time constant is derived and the computational complexities of MLMS algorithms are compared with those of the conventional LMS, sign, LFG, and QFG algorithms. The properties of convergence in the mean square are analyzed and the expressions of the mean square recursion and the excess mean square error are derived. The necessary condition for the CFG algorithm to be stable is attained. In the computer simulation applied to the system identification the CFG algorithm has the more computation complexities but the faster convergence speed than LMS, LFG and QFG algorithms.
A Study on the Design of Survivable Communication Networks
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1726~1734
This paper propose a survivable communication network design process using node degree that augments the usual traffic flow and cost analyses with previously ignored topological survivability and computing time considerations. At first, decide a initial topology, and then measure a throughput of network. If the throughput is smaller than the required traffic, add edge to the optimum place by using minimum node degree and link distance. Otherwise, drop useless edge by using maximum node degree, link distance and link utilization. This process is repeated until throughput equals to the required traffics. This Process designs a survivable communication network with the minimized cost and computing time and usual traffic flow. The design proceses that minimized computing time are freely select initial topology and easily design a large network. And these results of algorithm are compared with the Kris and Pramod's in order to analyses the perfmance of the designed network.
A NEW FAMILY OF FREQUENCY HOPPING PATTERNS WITH GOOD HAMMING AUTOCORRELATION AND CROSSCORRELATION
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1735~1741
New family of frequency hopping patterns with long period and good Hamming autocorrelation and Hamming crosscorrelation properties which can be used for frequency hopped multiple access communication systems is introduced. Period of frequency hopping patterns is qk-1, the alphabet size of frequency hopping patterns is q, and the size of family of frequency hopping patterns is q, where k is arbitrary integer and q is power of prime number. The maximum value of out-of-Phase Hamming autocorrelation function of any frequency hopping pattern and Hamming crosscorrelation function of any two frequency hopping patterns in the family is qk-1, which corresponds to optima1 Hamming correlation properties. And the average number of hits per q*q square in one frequency hopping pattern and its time shifted version or two frequency hopping patterns in the frequency hopped multiple access communication systems is less than 1.
Design and Implementation of A VXIbus Device for FFT Analysis
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1754~1766
The application of VXIbus system, an Industry standard, is rapidly spreading with its ability to offer the easiness of integration from GPIB and the fast data transmission from VMEbus system. Compared with VXIbus Register Based Device, VXIbus Message Based Device has a drawback In the aspect of speed. But it is possible to utilize high level ASCII commands to control a Message Based Device, therefore system integration is much easier with Message Based Device than with Register Based Device. And, the FFT analyzer is an instrument for signal analysis which can be inexpensively implemented to be fast and have high resolution. Its wide ability of analysis presents numerous application. So, it is necessary to apply VXIbus system to FFT analyzer. In this paper, the implementation of FFT analyzer is performed using a DSP module and by implementing all A/D conversion circuit and a control module which performs VXIbus interface. The device can be controlled by Slot0 Commender which supports VXIbus Shared Memory Protocol through VXIbus.
Impedance and Mutual Coupling Characteristics of a Probe-Fed Stacked Circular Microstrip Two-Element Array Antenna
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1767~1773
In this paper, the coupling characteristics as well as the self and the mutual Impedance of a two-element probe-fed stacked circular microstrip array antennas are presented. A full wave analysis for the structure is performed In the spectral domain using the vector Hankel transform(VHT). Also, we presented measured results for the impedance, the coupling characteristics of the antenna and the variation of the coupling with the distance between the two elements. Finally, the calculated and measured results are shown to agree well wlth each other through comparisons.
Design and Fabrication of the Broadband Microstrip Array Antenna with a Conical Radiation Pattern and the Circular Plarization
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1774~1784
This paper presents the design, fabrication and measured results of the broadband microstrip array with a conical radiation pattern and the circular array composed of six square microstrip antenna elements. Each element antenna has the stacked structure with a parasitic element to achieve a broadband characteristic and a branch line quadrature hybrid is attached to it for the circular polarization. The design procedures and measured results of the scheme for obtaining the conical radiation pattern which is useful for the mobile communication via the satellite. Finally, the performance of the fabricated antenna is measured and compared with the theory.
A Study on the Simplex and Distributed Multiplex type System for the Radar Data Processing
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 11, 1993, Pages 1785~1796
Thanks to the data processing facilities of modern digital computers, the performances of radar has been promoted greatly as one of the main components of command and control systems along with the computer communications. In this study, radar data integrating and processing systems were designed for the data processing of various information from many kinds of radar in a single data processing system. The performance of the data integrating system was analyzed by applying queueing theory. A radar data integrating network was designed for synchronous relational operations among the information processing systems and the transmission characteristics were also analysed by specific models for each system. The designed data integrating systems can be divided into a simplex type and a distributed multiplex type.