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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 22, Issue 12 - Dec 1997
Volume 22, Issue 11 - Nov 1997
Volume 22, Issue 10 - Oct 1997
Volume 22, Issue 9 - Sep 1997
Volume 22, Issue 8 - Aug 1997
Volume 22, Issue 7 - Jul 1997
Volume 22, Issue 6 - Jun 1997
Volume 22, Issue 5 - May 1997
Volume 22, Issue 4 - Apr 1997
Volume 22, Issue 3 - Mar 1997
Volume 22, Issue 2 - Feb 1997
Volume 22, Issue 1 - Jan 1997
Selecting the target year
A causal ordering algorithm using a new compression method
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1127~1136
A vector timestamp is used to satisfy message ordering in a group communications. In this paper, we propose a new vector timestamp compression method which is applicable to a single process group environment where one process belongs to only one precess group. An existing compression method compares the fields of the previously sent vector timestamp with thouse of the currently updated vector timestamp, then sends only the modified fields of the vector timestamp. Unlike the previous one, a proposed compression method performs individual compression for each process using the locally maintained vector timestamp information on other processes. Also, we logicallyproved the causal ordering algorithm using the new compression method and compared the performance of the proposed method with one of the previous compression method by computer simulation. Using the proposed compression method, the message overhead required for causal ordering can be reduced.
Design and performance analysis of fault tolerant multistage interconnection network with destination tag algorithm
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1137~1147
I propose a RZETA network consisted of switching elements(SEs) that have regular links and alternate links. A modified Zeta nework used for the RZETA network's regular links and a MIN used for its alternate links are generated using the graph theory. The RZETA network is driven from merging the formaer and latter MINs. A necessary and sufficient condition for modified Zeta network to be a nonblocking network is also presented. This condition is a ufficient condition for RZETA network with a faulty link or a faulty SE to be nonblocked. Performance of the RZETA network is analyzed by modification of the model of 2-dilated Banyan network and its performance is compared with existing redundant path networks, when packet arrival rate of each source is 1.
Performance analysis of a loss priority control scheme in an input and output queueing ATM switch
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1148~1159
In the broadband integrated service digital networks (B-ISDN), ATM switches hould be abld to accommodate diverse types of applications ith different traffic characteristics and quality ddo services (QOS). Thus, in order to increase the utilization of switches and satisfy the QOS's of each traffic type, some types of priority control schemes are needed in ATM switches. In this paper, a nonblocking input and output queueing ATm switch with capacity C is considered in which two classes of traffics with different loss probability constraints are admitted. 'Partial push-out' algorithm is suggested as a loss priority control schemes, and the performance of this algorithm is analyzed when this is adopted in input buffers of the switch. The quque length distribution of input buffers and loss probabilities of each traffic are obtained using a matrix-geometric solution method. Numerical analysis and simulation indicate that the utilization of the switch with partial push-out algorithm satisfying the QOS's of each traffic is much higher than that of the switch without control. Also, the required buffer size is reduced while satisfying the same QOS's.
A study on segmentation of vowels and consonants of noisy and distorted korean characters and their pecognition
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1160~1169
This paper presents an algorithm to separate vowels from consonants in Korean characters captured in noisy environment andto recognize them. The algorithm has been originally developed for recognition of the usage code (which is represented by a single Korean character) in the license plates of Korean vehicles. It, however, could be easily adopted to other applications with minor changes, in which character recognition is needed and the environment is noisy. The key ideas of the algorithm are to localize the vowels utilizing Hough transformation and to separate the vowels from consonants utilizing mathematical morphology. We observed that the presented algorithm effectively separates vowels even if the vowels and consonants are joined together after thresholding. We also observed that our algorithm outperforms some conventional algorithms especially when the input images are noisy. The details of the comparison study are presented in the paper.
Hierarchical transmission using morphology and vector quantization
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1170~1177
Morphology is a shape preseving filter. Several morphology filter can be made by the combination of morphological basic operation. If we use morphology filter in decimation process for a hierarchical encoder, there are some advantagesin reduction aliasing effects. In this paper, we propose a new hierarchical coder with morphological filtering and vector quantization. And then, firstly, we confirm that CO filtering is the best one among the 4 kinds of morphology filters to reduce aliasing effects in Laplacian pyramid transmission proposed by Burt. Secondly, the those two coders was compared. The results of our simulation show that our new coder surpasser the Laplacian pyramid especially in complex images.
An adaptive approximation of countours for a region-based image sequence coding
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1178~1184
Encoding of segment contours is a critical part of a region-based coding system especially at low bit rates where the contour information occupies a majority of the bit rate. When approximating contours with polygons, a fixed upper bound on the distortion is set for the approximation process. Instead of using this fixed bound, adaptive approximation bound for a lossy coding of contourts is proposed in this paper. A function representing the relative importance of the contour segmentis defined to take into account the spatial content of the image. By using this function, the contour can be approximated adaptively. This allows a more general approach than the methods with the fixed distortion measure. The effectiveness of the adaptive contour coding approach is verified through experiments.
A study on the implementation of scalable image capture processor using DRAM
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1185~1194
It is necessary to control the frame memory to capture, edit and display images. This paper presents the free-scale image capture processor size of which is user-defined, compared to the conventional image capture processor size of which is fixed 1/2, 1/4 and full size. User-defined scale data is fed into this system, which generates the gating pulses and gates the inputted image data. This system also controls the 4M DRAM instead of frame meamory. And stored gated image data are displayed on the TV monitor. We designed the scalable image capture parts and DRAM controller with ACTEL FPGAs, simulated the circuits with Viewlogic and fusing ACTEL A1020B chips. We confirmed the whole operation with beadboard which composed of "Philips TV Chipset" and designed FPGA chips.PGA chips.
Spatio-temporal video segmentation using a joint similarity measure
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1195~1209
This paper presents a new morphological spatio-temporal segmentation algorithm. The algorithm incorporates luminance and motion information simultaneously, and uses morphological tools such as morphological filtersand watershed algorithm. The procedure toward complete segmentation consists of three steps:joint marker extraction, boundary decision, and motion-based region fusion. First, the joint marker extraction identifies the presence of homogeneours regions in both motion and luminance, where a simple joint marker extraction technique is proposed. Second, the spatio-temporal boundaries are decided by the watershed algorithm. For this purposek, a new joint similarity measure is proposed. Finally, an elimination ofredundant regions is done using motion-based region function. By incorporating spatial and temporal information simultaneously, we can obtain visually meaningful segmentation results. Simulation results demonstratesthe efficiency of the proposed method.
A development of DS/CDMA MODEM architecture and its implementation
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1210~1230
In this paper, we suggest an architecture of DS/CDMA tranceiver composed of one pilot channel used as reference and multiple traffic channels. The pilot channel-an unmodulated PN code-is used as the reference signal for synchronization of PN code and data demondulation. The coherent demodulation architecture is also exploited for the reverse link as well as for the forward link. Here are the characteristics of the suggested DS/CDMA system. First, we suggest an interlaced quadrature spreading(IQS) method. In this method, the PN coe for I-phase 1st channel is used for Q-phase 2nd channels and the PN code for Q-phase 1st channel is used for I-phase 2nd channel, and so on-which is quite different from the eisting spreading schemes of DS/CDMA systems, such as IS-95 digital CDMA cellular or W-CDMA for PCS. By doing IQS spreading, we can drastically reduce the zero crossing rate of the RF signals. Second, we introduce an adaptive threshold setting for the synchronization of PN code, an initial acquistion method that uses a single PN code generator and reduces the acquistion time by a half compared the existing ones, and exploit the state machines to reduce the reacquistion time Third, various kinds of functions, such as automatic frequency control(AFC), automatic level control(ALC), bit-error-rate(BER) estimator, and spectral shaping for reducing the adjacent channel interference, are introduced to improve the system performance. Fourth, we designed and implemented the DS/CDMA MODEM to be used for variable transmission rate applications-from 16Kbps to 1.024Mbps. We developed and confirmed the DS/CDMA MODEM architecture through mathematical analysis and various kind of simulations. The ASIC design was done using VHDL coding and synthesis. To cope with several different kinds of applications, we developed transmitter and receiver ASICs separately. While a single transmitter or receiver ASC contains three channels (one for the pilot and the others for the traffic channels), by combining several transmitter ASICs, we can expand the number of channels up to 64. The ASICs are now under use for implementing a line-of-sight (LOS) radio equipment.
CPSN (complex Pi-sigma network) equalizer for the compensation of nonlinearities in satellite communication channels
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1231~1243
Digital satellite communication channels have nonlinearities with memory due to saturation characteristics of traveling wave tube amplifier in the satellite and transmitter/receiver linear filters. In this paper, we propose a network structure and a learning algorithm for complex pi-sigma network (CPSK) and exploit CPSN in the problem of equalization of nonlinear satellite channels. The proposed CPSN is a complex-valued extension of real-valued pi-sigma network that is a higher-order feedforward network with fast learning while greatly reducing network complexity by utilizing efficient form of polynomials for many input variables. The performance of the proposed CPSN is demonstrated by computer simulations on the equalization of complex-valued QPSK input symbols distorted by a nonlinear channel modeled as a Volterra series and additive noise. The results indicate that the CPSN shows good equalization performance, fast convergence, and less computations as compared to conventional higher-order models such as Volterra filters.
Analysis of waveguide iris using FEM-BIM its application to waveguide filter design
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1244~1250
An arbitrary shaped iris in rectangular waveguideis investigated using FEM-CDMA with triangularprism elements in this paper. The volume of irisis subdivided into a relatively small number of triangular prism elements and FEM is used to formulate the field distribution. On the other hand, the fields in the waveguide region are represented by BIM derived from the waveguide Green's function and boundary conditions. The proposed method is verified through the design and experiment for the circular iris filter using WR-90 waveguide.
2-state 5-pole bandpass filter consisted of dual and tripe-mode cavity resonator
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1251~1258
Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T
-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T
-modes, and by two orthogonal T
-modes and one T
-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.
A geometric analysis of range measurement error
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1259~1265
We investigate depth measurement error of a range finder based on triangulation method. Geometric analysis resulted in intuitive understanding of the error sensitivity. We show that the depth error is propostional to the distance between the object andthe camera. The measurement value has the highest accuracy when the line connecting the focal point of the camera and the object is perpendicular to the line joining the object and the light source of herange finder. Also we analyze the error using a perturbation method and verify that the results are identical through an experiment.
Design and performance evaluation of the software RAID file system in the NOW environment
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1266~1272
Due to the price and performanceof uniprocessor workstations and off-the shelf networking, network of workstations(NOW) ae now a cost-effective parallel processing platform tht is competitive with supercomputers. Meanwhile, current network fiile system protocols rely heavily on a central server to coordinate file activity among client workstations. This central server can become a bottleneck that limits scalibility for environments with large numbers of clients. In this paper, we propsoe a highly reliable and effective software RAID file system on the network of workstation environment. We present results form a trace-driven simulation study that shows that the designed software RAID file system is more effective in the aspect of elapsed time when compared with client/server file systems.
Hall's Sextic Residue 시퀀스 및 기타 시퀀스의 Trace 함수에 의한 표현
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1273~1278
Pseudonoise sequences of period 2
-1 with idel autocorrelation have been researched such as m-sequences, GMW sequences, Legendre sequences, and extended sequences. The m-sequences, the GMW sequences, the Legendre sequences, and the extended sequences are best described in terms of the trace function by previous works. Besides, there are Hall's sextic residue sequences and miscellaneous sequences with ideal autocorrelation, whose general constructions are not known so far. However, are are no explicit descripton of the Hall's sextic residue sequences and the miscellaneous sequences in terms of the trace function. In this paper, the Hall's sextic residue sequences and the miscellaneous sequences of period 2
-1 are expressed as a sum of trace functions. The miscellaneous sequences with ideal autocorrelation, which are newly found by computer search, are also expressed as a sum of trace functions.
Fast fractal coding based on LMSE analysis and subblock feature
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1279~1288
In this paper, we propose a fast fractal coding method based on LMSE analysis and subblock feature. In the proposed method, scaling paarameter is calculated and whether search for each domain block should be done or not is determined based on the LMSE analysis of fractal approximation, and isometry parameter is chosen based on subblock feature. To investigate the efficiency of the proposed method, we compared it with Jacquin's method on image quality and encoding time. Experimental results show the proposed method yields nearly the same performance as that of Jacquin method in PSNR, and its encoding time is reduced by about 1/7 times.
A study on the characteristics of DP-PLL in a SDH-based network
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1289~1301
In a SDH network, one of the most important issues is the realization of network synchronization. In this paper, we presented the relationship between parameters and control algorithm of DP-PLL for design in a SDH based time, SSM processing time, PJE counter and reference switching time, and analyzed phase transients for one node and mutiple nodes through our simulation results with a standard specification. We suggested suitable design method of SDH-DP-PLL.
Dynamic code allocation using voice activeity detection in DS-CDMA cellular system
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1302~1310
In this paper, we propose a dynamic code allocation strategy using voice activity detection and evaluate the performance of a dynamic code allocation strategy using voice activeity detection in DS-CDMA system. Proposed method allocates code to mobile terminal according to the residual capacity computed by SIR in the base station. In hot spot traffic loading cell, we find that the performance of proposed method is better than that of a fixed code assignment strategy using voice activity detection. Also, we find that the proposed method provide much improvement in blocking probability against the dynamic code assignment strategy withoug voice activity detection.
Performance monitoring and fault node identification method for real-time ATM network management system
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1311~1322
Performance management of ATM network is urgently required because a different quality of service should be guaranteed on each connection. A lot of performance measurement data increase the burden on agent systems and on managment stations. In this paper, an effective OAM-based performance monitoring and faulty node identification technique is proposed. A proposed VP Selection Algorithm reduces management-related traffic and when the indication of hard or soft failure state is detected, failed node is identified by Fault Identification Rule.
The design and performance evaluation of a high-speed cell concentrator/distributor with a bypassing capability for interprocessor communication in ATM switching systems
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1323~1333
In this paper, we propose an efficient architecture for a high-speed cell concentrator/distributor(HCCD) in an ATM(Asynchronous Transfer Mode) switch and by analyzeing the simulation results evaluate the performance of the proposed architecuture. The proposed HCCD distributes cells from a switch link to local processors, or concentrates cells from local processor s to a switch link. This design is to guarntee a high throughput for the IPC (inter-processor communication) link in a distributed ATM switching system. The HCCD is designed in a moudlar architecture to provide the extensibility and the flexibility. The main characteristics of the HCCD are 1) Adaption of a local CPU in HCCD for improving flexibility of the system, 2) A cell-baced statistical multiplexing function for efficient multiplexing, 3) A cell distribution function based on VPI(Virtual Path Identifier), 4) A bypassing capability for IPC between processor attached to the same HCCD, 5) A multicasting capability for point-to-multipoint communication, 6) A VPI table updating function for the efficient management of links, 7) A self-testing function for detecting system fault.
A multimedia synchronization mechanism using receiver buffer-level
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1334~1342
The future data communications are expected to support the various andcomplex services withmultimedia. So thispaper has focused on the multimedia synchronization problem which has important position in multimedia presentation. Firstly, this paper consider the suitable layer for multimedia synchronization in the communication structure as transport layer or upper ones, in which we propose synchronization mechanism using fixed length buffer with bufer-lever or upper ones, in which we propose synchronization mechanism using fixed length bufer with buffer-level. The proposed mechansim also supports intra-and inter-media synchronization among media. Through simulation, we prove our analysis of the fixed-length buffersize that theproposed mechanism can provide. Also we show comparisons between our mechanism and other scheme.
A study on the design of a VODB using different kinds of protocol
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1343~1355
Full motion video data is the most effective data type that transmits information in multimedia enviornment. VOD service is system that uses network to transmit full motion video data interactively. Therefore VOD service system must satisfy the following requirements. First, it should transmit high quality full motion video. Second, it should be able to control a large quantity of full motion video. Third, a user should be able to retrieve the full motion vide effectively. However the existing VOD service system is established based n file system that not only does it have disadvantages in managment such as transaction control but also it is not suitable for distributed multimedia environment. The goal of this research is to build a VOD service system that provides high-quality full motion video assuming information retrieval. In order to mainly search video data's bibliographical information and to manage related information, VOD service system and DBMS system are to be closely related. Also, to transmit high quality full motion video data, we use MTP
(Media Transfer Protocol) developed by StarLight. MTP
guarantees high bandwidth that is necessary to tansmit high quality full motion video data effectively. In other hand TCP/IP which is used for information search does not guarentee high bandwidth as that in MTP
. Therfore VOD service system that seraches information managed by DBMS and transmits requried full motion video data should control different kinds of protocol simultaneously. This paper describes the configuration of VODB system that has solved these problems, implementation and efficiency of data applied system.stem.
Modelling and implementation scheme of a multi directory for multiple applications
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1356~1364
This paper presents a modelling and implementation scheme of a multi directory which provides location and supplementary information of multiple applications in distributed environments. An extrended directory schema and extended DIT(Directory Information Tree) model is proposed for the multi directory. For implementation scheme, an implementation example adapted for the DFR(Document Filing and Retrieval) is shown. In addition, a configuration model for interworking between the DFR and the multi directory, an association mechanisms between two application's operations are also described. In a distributed environment, the interworking between the DFR and a multi directory implemented by using QUIPU 8.0 of ISODE(ISO Development Environment) directory system is tested. Based on the result of this paper, an extended model ofthe directory system is proposed for providing search operation of various application' objects.
Implementation technique of execution time predictable real-time mechanism control language
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1365~1376
In this paper, we designed real time mechanism control language and proposed execution time analysis technique. It was impossible to handle real-time mechanism control programs like programmable controller, numerical controller, distributed control system and robot controller with general purpose programming languages and operating systems because they have to process electric signals generated by thousands of sensors at the same at the same time and in real time. So we made it possible to predict plausibility of time constraint constructs of tiem constraint construct of a real time application program at compilation time by adding time constraint constructs and mechanism synchronization structure to conditional statement and iteration statement of a programming language and developing execution time analysis technique.
Implementation of fast forward function in video on demand service system
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 6, 1997, Pages 1377~1384
We propose a new scheme to provide the fast forward and reverse(FF/R) functions to users in Video On Demand Service System. The proposed scheme is to use only I and P pictures obtained by sampling MPEG2 bit-steam. New frame raes for FF/R play are specified with parameters of MPEG2 syntrx. Bits of I and P pictures are reduced in three steps: Variable length decoding(VLD), Inverse quantization and Requantization. The proposed scheme is ecnomical in the sense that it can provide FF/R function without any additional requirement on the bandwidth and on the storage media in video server.