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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 Study on the Stability and Design of Compensator for Bounded Control Input Signal
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1413~1421
It is possible to weaken the undesirable effect of a bounded control input signal to the plant and done by setting up an additional correction loop which compensates for the suppresed portion of the control input signal. The design and analysys of stability of state controller is used by the Kalman-Szego-Lemma and as the result of this method is made possible to take advantage of the control input to the plant even for small error signals.
Speaker-Independent Korean Digit Recognition Using HCNN with Weighted Distance Measure
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1422~1432
Nonlinear mapping function of the HCNN( Hidden Control Neural Network ) can change over time to model the temporal variability of a speech signal by combining the nonlinear prediction of conventional neural networks with the segmentation capability of HMM. We have two things in this paper. first, we showed that the performance of the HCNN is better than that of HMM. Second, the HCNN with its prediction error measure given by weighted distance is proposed to use suitable distance measure for the HCNN, and then we showed that the superiority of the proposed system for speaker-independent speech recognition tasks. Weighted distance considers the differences between the variances of each component of the feature vector extraced from the speech data. Speaker-independent Korean digit recognition experiment showed that the recognition rate of 95%was obtained for the HCNN with Euclidean distance. This result is 1.28% higher than HMM, and shows that the HCNN which models the dynamical system is superior to HMM which is based on the statistical restrictions. And we obtained 97.35% for the HCNN with weighted distance, which is 2.35% better than the HCNN with Euclidean distance. The reason why the HCNN with weighted distance shows better performance is as follows : it reduces the variations of the recognition error rate over different speakers by increasing the recognition rate for the speakers who have many misclassified utterances. So we can conclude that the HCNN with weighted distance is more suit-able for speaker-independent speech recognition tasks.
Design of DCT/IDCT Core Processor using Module Generator Technique
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1433~1443
DCT(Discrete Cosine Transform) / IDCT(Inverse DCT) is widely used in various image compression and decompression systems as well as in DSP(Digital Signal Processing) applications. Since DCT/ IDCT is one of the most complicated part of the compression system, the performance of the system can be greatly enchanced by improving the speed of DCT/IDCT operation. In this thesis, we designed a DCT/IDCT core processor using module generator technique. By utilizing the partial sum and DA(Distributed Arithmetic) techniques, the DCT/ IDCT core processor is designed within small area. It is also designed to perform the IDCT(Inverse DCT) operation with little additional circuitry. The pipeline structure of the core processor enables the high performance, and the high accuracy of the DCT/IDCT operation is obtained by having fewer rounding stages. The proposed design is independent of design rules, and the number of the input bits and the accuracy of the internal calculation coa be easily adjusted due to the module generator technique. The accuracy of the processor satisfies the specifications in CCITT recommendation H, 261.
An Automatic Engagement Robot System Using Combined Acoustic and Visual Sensors
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1444~1453
Multiple Scattering of the Electromagnetic Wave by Randomly Distributed and Closely Located Cylindrical Scatterers
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1454~1460
The scattering pattern, due to an E-Polarized wave incident on M circular parallel dielectric cylinders, is computed. The multiply-scattered fields between the cylinders are considered. Modeling of infinite cylindrical scatterer of arbitrary cross sections by a number of circular cylinders is executed. By enforcing the boundary conditions on the surface of each cylinder, an infinite set of equations is obtained. The first order of scattering results from the excitation of each cylinder by only the incident wave. The second order results from the excitation of each cylinder by the first order of scattering from the remaining cylinders, and so no to an infinite order of scattering. Although the resulting equation is of infinite size, proper truncation yields very accurate numerical results.
An Analysis of the Wave Properties in an Inhomogeneous Anisotropic Medium using Variational Reaction Theory
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1461~1468
In this paper the propagation problem of waves obliquely incident upon an anisotropic medium with arbitrary permittivity tensors is analyzed through a partial variational finite element method. First, a variational equation is derived from the new approach based on the induction theorem, reactions, and reciprocity. Next, by using the finite element method, the propagation problems are solved from the obtained functional. Also included are numerical results for the problem of waves incident upon a magnetoplasma slab.
Adaptive Image Coding Technique using HVS in Biorthogonal Wavelet Transform Domain
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1469~1482
A new image coding technique has been proposed based on the wavelet transform. To achieve lower ceding rates and good qualities in reconstructed images, some of wavelet coefficients were removed by thresholding and quantized in accordance with the sensitivity of the human visual system(HVS). For each block of subimages in wavelet transform domain, block thresholding scheme has been used to remove the unimportant wavelet coefficients according to the frequency characteristic and statistical property of wavelet coefficients. The location information of quantized blocks and removed blocks were encoded using run-length coder which is effective for the exponential distribution. Quantized coefficients were encoded using variable length coder which matches well to their distribution. Simulation results show that the reconstructed images maintain high quality with the low bit rate, below 1.0 bits per pel.
A Welfare Economics Approach of Frequency Assignment
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1483~1494
Most studies analyse the frequecny polities intuitively based on the assumptin that there is no question in the frequency regulation by the government. But this paper started from the concept of frequency as economic goods. This paper conclude that frequency regulation by the government is needed to redistribute the economic surplus causing excessive demand. There are five methods in the frequency assignment-comparative healing, auction, lottery, Joint consortium and pioneer preference. The five methods are studied form the view of welfare economics and the respective political Implications are proposed in this paper.
Design of A Reed-Solomon Code Decoder for Compact Disc Player using Microprogramming Method
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1495~1507
In this paper, an implementation of RS (Reed-Solomon) code decoder for CDP (Compact Disc Player) using microprogramming method is presented. In this decoding strategy, the equations composed of Newton's identities are used for computing the coefficients of the error locator polynomial and for checking the number of erasures in C2(outer code). Also, in C2 decoding the values of erasures are computed from syndromes and the results of C1(inner code) decoding. We pulled up the error correctability by correcting 4 erasures or less. The decoder contains an arithmetic logic unit over GF(28) for error correcting and a decoding controller with programming ROM, and also microinstructions. Microinstructions are used for an implementation of a decoding algorithm for RS code. As a result, it can be easily modified for upgrade or other applications by changing the programming ROM only. The decoder is implemented by the Logic Level Modeling of Verilog HDL. In the decoder, each microinstruction has 14 bits( = 1 word), and the size of the programming ROM is 360 words. The number of the maximum clock-cycle for decoding both C1 and C2 is 424.
Modeling and Evaluation of Wireless Communication System using CSMA inthe Distributed Packet Radio Network
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1508~1517
In this paper, we propose the modeling of a wireless communication system using CSMA protocol, present analytical evalution and simulation as a function of arrival rate and mean END-to-END delay in the distributed packet radio network. Asynchronous 1-persistent CSMA protocol is used in wireless communication system with half duplex. We assume that all terminals are to be in the close range of each other, suitably located in the local area. The traffic presented to a common channel is assumed to be poisson distribution. Analytical model is based on a M/D/1 with breakdown. In conclusion for wireless network model proposed in this paper is suitable for packet arrival rate of 2 packet/sec with mean packet delay time less than 2 times the packet transmission time.
A Design of a Data Predistorter for the Compensation of Nonlinearities in High Power Amplifiers for Satellite Communication
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1518~1526
It has been known that the amplifiers for high power signal in satellite communication channels suffer from nonlinear distortions, which reduce the performance of the communication channel significantly. In order to compensate the nonlinear distortion, a new data predistortion method with the LMS algorithm is proposed in this paper, Whereas the previous approach handles this problem by assigning corresponding predistorter to each symbol for the case of 16-QAM, the proposed approach uses the same memory for the symbols, which have identical amplitudes, and predistors the input of high-power amplifiers by the amplitude and phase differences, resulting in better adaptive data predistorter with small number of digital memory (3 predistorters) and fast convergence rate. Superiority of the proposed approach in the paper is demonstrated by comparing it with the previous approach.
Microcode-based Output Pulse Generation for Remote Controller Application
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1527~1536
A new transmitter circuit for remote controllers is designed to provide flexibility and expandibility in function. The circuit employs a microcode approach to accept various code format, length and pulse widths through programming, and the precessing logics is eliminated to reduce its size. The circuit was Implemented using FPGA(Field Programmable Gate Array) and it was found to operate successfully).
Design of Fault Position Detectable Pattern Generator for Built-In Self Test
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1537~1545
In this paper, we design a pattern generator and a fault position detector to implement the proposed fault test algorithms which are Column Weight Sensitive Fault (CWSF) test algorithm and bit line decoder fault test algorithm for performing the Built-In Self Test(BIST) in RAM. A pattern generator consists of an address generator and a data generator. An address generator is divided into a row address generator for effective address and a column address generator for sequential and parallel addresses. A fault position detector is designed to determine whether full occurred or not and to find the position of the fault. We verify the implemented circuits by the simulation.
Adaptive Block Truncation Coding Based on Gradient Information
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1546~1552
We proposed an adaptive block truncation coding(BTC) using gradient and a new initial value. We used gradient of sobel operator as a new category classification coefficient to reduce Jagged appearance at edge part. We defined a new initial value to reduce large quantization error in the 4-level quantizer block including edge part. By computer simulations, we showed that the proposed method less computation load, reduced jagged appearance at edge part, also improved PSNR more than the conventional adaptive BTC.
Reconfiguration Problems in VLSI and WSI Cellular Arrays
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1553~1571
A significant amount of research has focused on the development of highly parallel architectures to obtain far more computational power than conventional computer systems. These architectures usually comprise of a large number of processors communicating through an interconnection network. The VLSI (Very Large Scale Integration) and WSI (Wafer Scale Integration) cellular arrays form one important class of those parallel architectures, and consist of a large number of simple processing cells, all on a single chip or wafer, each interconnected only to its neighbors. This paper studies three fundamental issues in these arrays : fault-tolerant reconfiguration. functional reconfiguration, and their integration. The paper examines conventional techniques, and gives an in-depth discussion about fault-tolerant reconfiguration and functional reconfiguration, presenting testing control strategy, configuration control strategy, steps required f4r each reconfiguration, and other relevant topics. The issue of integrating fault tolerant reconfiguration and functional reconfiguration has been addressed only recently. To tackle that problem, the paper identifies the relation between fault tolerant reconfiguration and functional reconfiguration, and discusses appropriate testing and configuration control strategy for integrated reconfiguration on VLSI and WSI cellular arrays.
A Nondeterminism Removal Algorithm for Efficient Testing of Communication Protocols
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1572~1581
DFSM(Deterministic Finite State Machine) is used because it easily represents the control flow of a protocol in the protocol specification. Real protocols contain problem of nondeterminisms that have more than one enabled transition in the same state by same input. But DFSM does not process nondeterminism. So, in this paper, we first specify a protocol with NFSM (Nonderministic FSM) that may show the characteristics of nondeterminism, and propose an algorithm which converts NFSM to DFSM.
Detection of Lines and Ellipses using Hough Transform
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1582~1589
This paper presents a method of detecting lines and ellipses from the image by using Hough transform(HT) known as a robust line detection method against noise. Lines are first detected by conventional HT. Then points of the lines are eliminated to reduce the calculation cost and to ease detection of ellipses. For ellipse defection, parameters of the ellipse are calculated by Least Square Method using particular points that contain geometric properties of the ellipse, instead of accumlating Hough array. Circles are detected in the same way as ellipse detection.
DC-DC Converter for Integrated Voltage Control Method
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1590~1597
Power conversion system generally requires bidirectional converter. A storage energy of reactor is suppressed by regeneration of surplus electic energy in converter to power source. When an electric isolation in the power conversion system is required. the most suitable position for the isolation is the DC-Link part. A transformer in the DC part is minimized because of high repetition frequency. This paper proposes that power conversion system becomes bidirectional DC-DC converter with electric isolation by intergrated voltage control method. It is intergrated voltage control that makes system construciton simple, has control errow little quantity ans gets output response Quick. And the power-switches which should be operated is selected automatically without a detection of the current-direction.
Performance Degradation for a Data timing error and a Receiver filtering effect on Digital mobile system
The Journal of Korean Institute of Communications and Information Sciences, volume 18, issue 10, 1993, Pages 1598~1605
In this paper, the performance degradation caused by the band pass filter and the data sampling timing error which are generally considered ideal for the simplicity was analyzed. The well known intersymbol interference theory can be applicable to calculate only the upper bound of a system performance. Therefore to obtain the average error probability, a method average intersymbol interference was proposed. This method can be applicable to obtain average error probablity with a computer simulation and with a measured value in test lab. easily.