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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 25, Issue 12B - Dec 2000
Volume 25, Issue 12A - Dec 2000
Volume 25, Issue 11B - Nov 2000
Volume 25, Issue 11A - Nov 2000
Volume 25, Issue 10B - Oct 2000
Volume 25, Issue 10A - Oct 2000
Volume 25, Issue 9B - Sep 2000
Volume 25, Issue 9A - Sep 2000
Volume 25, Issue 8B - Aug 2000
Volume 25, Issue 8A - Aug 2000
Volume 25, Issue 7B - Jul 2000
Volume 25, Issue 7A - Jul 2000
Volume 25, Issue 6B - Jun 2000
Volume 25, Issue 6A - Jun 2000
Volume 25, Issue 5B - May 2000
Volume 25, Issue 5A - May 2000
Volume 25, Issue 4B - Apr 2000
Volume 25, Issue 4A - Apr 2000
Volume 25, Issue 3B - Mar 2000
Volume 25, Issue 3A - Mar 2000
Volume 25, Issue 1B - Jan 2000
Volume 25, Issue 1A - Jan 2000
Volume 25, Issue 9 - 00 2000
Volume 25, Issue 8 - 00 2000
Volume 25, Issue 7 - 00 2000
Volume 25, Issue 5 - 00 2000
Volume 25, Issue 4 - 00 2000
Volume 25, Issue 2B - 00 2000
Volume 25, Issue 2A - 00 2000
Volume 25, Issue 1 - 00 2000
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Volume 25, Issue 10 - 00 2000
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An Implementation of a ATMARP Multiple Server on the LINUX
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 399~407
Recently, supporting ATM networks under LINUX operating systems environment has been actively studied. An ATMARP server in a conventional LINUX environment was designed under the ATMARP single-server to operate independently within a Local IP Subnet(LIS). In this paper, an ATMARP multi-server is introduced and implemented an ATMARP-server managing multiple LIS's on the LINUX-based IPOA. The ATMARP protocol processing functions and addition/deletion functions on management tables are required to implement the ATMARP multi-server. These functions can solve the problem of increasing the number of ATMARP servers in ATMARP single-server environment. The file transmission experiment with a connection configuration between LIS's shows that multiple LIS' con be managed by an ATMARP-server. As the results, the ATMARP multi-server scheme yields a smaller number of servers than that of the conventional ATMARP single-server scheme, and the network composition can be improved substantially.
Generalized Vector Channel Model for Communication Systems Using Antenna Arrays and Implementation of the Spatial Channel Simulator
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 408~422
In this paper, we propose a generalized vector channel model for wireless communication systems using antenna arrays. The proposed channel model reflects path loss. spatial-temporal variation of shadowing, multipath fading , Doppler effect, spatial distribution of local scatterers and delay spread due to remote dominant scatterers. In addition, we use a discrete ray model in which respective ray signal experiences independent shadowing, fading and Doppler shift, and impinges on antenna arrays at a distinct angle. Based on the proposed mode. we derive the relations on the spatial and temporal correlations of the received signals and implement a spatial channel simulator. By comparing the theoretical values with the simulated ones, we verify the effectiveness of the implemented simulator. The simulator is then used to generate an arbitrary channel impulse response and to analyze the channel characteristics under various environments.
A Method for the Performance Ehancement of PRMA Protocol for Mobile Voice/Data Integration
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 423~430
Future microcellular systems will require distributed network control. A packet-switched network is suitable for this requirement. The packet reservation multiple access(PRMA) is a Reservation-ALOHA like protocol for wireless terminals to transmit packet speech to a base station. It allows spatially distributed users in cellular systems to transmit packeted voice and data to a common base station using a shared channel. In the existing PRMA, the problem is that the voice packets may collide with the data packets due to simultaneous channel access. the problem may be a major performance degradation factor to a voice and data mixed system. We propose a new PRMA method that integrates voice and data traffic efficiently by resolving the collision problem between data and voice packets. The proposed PRMA method gives a performance improvement than the existing PRAMA method in terms of voice packet dropping probability and data delay characteristic. From analytic results, we can confirm that the proposed PRMA method show a performance improvement than the existing PRMA protocol.
Multimedia Synchronization Method for Presenting Event Objects
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 431~436
It is required for us to design multimedia synchronization model which present mixed media, tat contains not only continuous medial but also discontinuous media. And it is useful for us to develop multimedia application software. Proposed paper represents model tat expresses continuous media and discontinuous media. And continuous medial show the temporal relations between media objects then discontinuous media spatial relations. The model proposed in this paper is effective in applying the system to guarantee high quality of services and can process real time application form applying efficient multiple key media when events occur. We verified that the proposed model has improved media palyout rate compared with other previous synchronization models through simulation.
Performance Evaluation of Label Switching in ATM networks.
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 437~445
More advanced and demanding applications, like videoconferencing, video on demand. distributed computing etc., have been devised thanks to the availability of enhanced network feature. Network technologies need to be enhanced to support these applications and to cope with the increasing number of users. Increasing the availability of network resources is just not enough to achieve this goal; scalable network architecture. increased packet forwarding capabilities, a wider range of services are all additional requirements. MOLS (multiprotocol label Switching) is one of the new networking techniques under standardization in the scientific community. In this paper, we analyze the performance of label switching in ATM networks. Simulation tests were performed. In this simulation, we set a simple network configuration and used internet traffic traces from NLANR as input traffic sources. The simulation results and analysis will be helpful in utilizing the functions of ATM switching and IP routing.
A Study on the line characteristics and coverage of FLC-C VDSL system.
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 446~455
In this paper, we analyzed the reach performance of the FLC-C VDSL system using 4-CAP modulation scheme. We measured the attenuation of VDSL lines and their noise characteristics, and calculated the channel capacity. And then, we evaluated the VDSL coverage fro each type of cables; CPEV 0.5mm, CPEV 0.65mm, UTP3 0.5mm, UTP5 0.5mm, FS 0.4mm, FS 0.5mm. In case that FLC-C VDSL modern transmits 25.92 Mbps data over a UTP5 0.5mm cable, the VDSL reach appears to be about 570mm.
A comparison of MAC protocols IEEE802.14 vs MCNS MAC for HFC Networks Depending on Traffic Types.
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 456~463
Bidirectional cable TV networks using HFC(Hybrid Fiber Coaxial) networks need MAC (Medium access control) protocols to have efficient access in upstream channels. In this paper, we have studied and evaluated several contention resolution algorithms and mapping of higher layer traffic described in IEEE 802.14 and MCNS (Multimedial Cable Network System) MAC protocols with respect to IP, ABR and CBR traffic types. IEEE 802.14 MAC protocol demonstrates better performance for transmitting ATM cells while the MCNS MAC protocols for the IP traffic.
An Efficient Method that Incorporate a Channel Reliability to the Log-MAP-based Turbo Decoding
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 464~471
The number of quantization bits of the input signals
need to be optimally determined through the trade-off between the H/W complexity and the BER performance in Turbo codes applications. Also, an effective means to incorporate a channel reliability
in the Log-MAP-based Turbo decoding is highly required. because it has a major effect on both the complexity and the performance. In this paper, a novel bit-shifting approach that substitutes for the multiplying is proposed so as to effectively incorporate.
in Turbo decoding. The optimal number of quantization bits of
is investigated through Monte-Carlo simulations assuming that bit-shifting approach is adopted. In addition. The effects of an incorrect estimation of noise variance on the performance of Turbo codes is investigated. There is a confined range in which the effects of an incorrect estimation can be ignored.
Performance improvement of multiuser detection using antenna array in CDMA base station
Nam, Jong-Gil ; Lee, Weon-Chul ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 472~486
This paper analysis the performance of joint receiving structure consisting of the decorrelating multiuser detection and beamfromenr-RAKE receive for DS-CDMA communication systems. In asynchronous transmission as the number of simultaneous users increase. the capacity of CDMA system becomes severly reduced due to the nonideal orthogonality between user-assigned PN sequences and improper power control. Accordingly, the CDMA receiving system becomes vulnerable to the multiple access interferences and the near-far problem under multipath fading channel environment. To withstand these undesired performance degradations, this paper proposes the new type of multiuser detection which has a form of the hybrid structure of concatenating beamformer-RAKE receiver and decorrelating multiuser detection. the beam former-RAKE receiver performs temporal and spatial diversity combining with alleviating fading effect and suppressing undesired interferences, and the multiuser detection plays a role of making the receiver robust to the near-far problem. Regarding the individual merit on the usage of either multiuser detection or beamformer-RAKE receiver, the hybrid one is expected to produce the enhanced performance in multipath fading CDMA channel. However major drawback of using decorrelating multiuser detection for practical deployment is arised from its computational complexity , which is exponentially increased as more number of users and transmitted symbols involve. To diminish the computational complexity, this paper exploits an efficient block Toeplitz inversion technique using matrix Levinson polynomial will be introduced. And this paper provided the mathematical analysis to show the efficiency of the proposed joint structure under the multipath propagation environment. And results of a series of exhaustive computer simulations are presented in order to demonstrate the overall performance of the proposed hybrid structure in multipath fading CDMA channel.
Performance improvement of TCP over ATM using RM cell information
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 487~492
The ABR(available bit rate) service has been developed to support data application over ATM(asynchronous Transfer mode) networks, and TCP is the most widely used transport layer protocol in existing data networks. Thus, the performance improvement of TCP over ABR is an issue of cardinal importance. In this paper, we propose algorithm of the adjustment of congestion window size utilizing RM(resource Management) cell information. The motivation is to use more reliable information in ER(explicit rate) field within RM cell to determine TCP window size. Simulations are performance using the suggested algorithm is improved, as compared to TCP-reno.
New conter location algorithms for shared multicast trees
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 493~503
Multicast routing algorithms such PIM, CBT, BGMP use shared multicast routing trees and the location of the multicast tree has great impact on the packet delay. In this pater we propose three new center location algorithms and analyze their performance through simulation studies. these three algorithms consider as candidates for the center not only multicast group members but also a few non-members nodes. To select these non-member nodes, we first find all the shortest paths among every couple of members and consider either nodes which are most frequently visited during the process of finding shortest paths or nodes which lie at the center of a shortest path and are most frequently visited during the same process. There the proposed algorithms are able to find the better center than not only algorithms which consider only member nodes but also other algorithms which consider selected non-member nodes in addition ot member nodes. The proposed algorithms either incur too much overhead nor depend upon unicasting algorithms.
A Study on the operation and Maintenance system for optical subscriber loops using a broadband light source
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 504~509
This paper presents a noble operation and maintenance system for the optical subscriber loops and its feasibility through several experiments. In this system, a broadband CW (Continuous Wave) light source I used as monitoring of testing signals. and a FGF(Fiber Grating Filter) of which reflective wavelength is independent, is inserted somewhere in each subscriber loop for the reflection of monitoring of testing signals. The propose of the system is quick decision. whether the loop is just fault or not. rather than detailed information of loop state. At present, most of operation and maintenance system for the optical subscriber loops adopts OTDR(optical time domain reflectometer) for testing function. the OTDR is useful for detailed test, but not adequate for simple test because of long testing time . And it is difficult to test PON network by using general OTDR that has a single-wavelength light source. Compared to using OTDR, the proposed system can afford to shorten testing time and to test PON network. Moreover, we can cut down the system cost by simplifying circuits of the optical light sources. Our results show that the proposed system operates well according to the purpose mentioned above.
Interframe interpolation technique based on variable skip rate
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 510~518
A new video interpolation technique based on variable skip rate of video sequence is proposed in this paper. in the proposed technique. the determination whether a frame is skipped or not is done by the degree of motion complexity of the frame. If the motion complexity of a frame is low the frame is skipped. otherwise it is coded and transmitted. To determine the motion complexity of a frame a new technique using MEF (moving edge in frame),the set of pixels considered as moving edges in a frame. is introduced. In the course of decoding and interpolating of receiver., the motion field is segmented. For the purpose of dividing vector field morphological filtering is applied. Morphological filtering also used to smooth the boundaries between the changed and unchanged region. In the simulation results, the proposed technique shows higher quality and lower fluctuation of picture quality than the conventional techniques on conditioning of the same bit rate.
Fractal Coding scheme using reference Images
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 519~528
This pater presents a new fractal coding scheme to find more optimal transformation using the reference images which I determined by some criteria. After finding the transformations to minimize the distance between the original image and the reference images. we choose one of them which has the best performance. Conventional fractal coding schemes based on the collage theorem obtain the transformation to minimize the distance between an original image and its collage image because of heavy computation. In other words, it is because the optimal transformation and be obtained after the attractors of all the possible transformations are generated and then compared with an original image. As such a procedure is practically difficult to implement. the collage coding schemes using the theorem have widely used, We introduce the new scheme to overcome the complexity problem for the optimal transformation and be obtained, our scheme is evaluated. as compared with the optimal one, In general cases that the optimal one is unavailable. our scheme is also evaluated, as compared with the conventional schemes.
A Semantic-based rate control method for motion video coding
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 529~540
This is paper presents the semantic based rate-control method which is based on very low bit rate video coding standards H.263 plus, applied on very low bit rate applications. Previous rate control methods control the generated bit rates by setting the optimum quantization parameters per macro block unit on frame. But, in this paper, we added the pre-processing algorithm, semantic region recognition and assignment of priority algorithm, to obtain the subjective quality enhancement. This work aims to improve the subjective quality of skin color region or face by using unimportant background region's bit resources.
Performance Analysis and improvement of Extension-interpolation (EI)/2D-DCT for Coding irregular Shaped object
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 541~548
In the MPEG-4 standardization phase, many methods for coding the irregular shaped VOP (video object Plane) have been researched. Texture coding is one of interesting research items in the MPEG-4. There are the Low pass extrapolation (LPE) padding, the shape adaptive DCT (SA-DCT), and the Extension-Interpolation (EI)/2D-DCT proposed in  as texture coding methods. the EI/2D-DCT is the method extending and interpolating luminance values from and Arbitrarily Shaped (AS) image segment into an 8 x 8 block and transforming the extended and interpolated luminance values by the 8x8 DCT. although the EI/2D-DCT and the SA-DCT work well in coding the As image segments. they are degraded since they use one-dimensional (1-D) methods such as the 1D-EI and the 1D-DCT in the two-dimensional (2-D) space. in this paper, we analyze the performance of the EI/2D-DCTand propose a new non-symmetric sig-sag scanning method, which non-symmetrically scans the quantized coefficients in the DCT domain to improve the EI/2D-DCT.
Stereo object Tracking System using Block Matching Algorithm and optical JTC
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 549~556
In this paper, we propose a new adaptive stereo object tracking system that can be used when the back ground image is complex and the cameras are not fixed . In this method, we used the Block Matching Algorithm to separate the tracking object form the background image and then the optical JTC system is used to obtain the convergence-controlling and pa/tilt-controlling values fro the left and right cameras. the experimental results are found to track the object robustly & adaptively for the object tracking in various background images, and the possibility of real-time implementation of the proposed system by using the optical JTC is also suggested.
Robust pattern watermarking using wavelet transform and multi-weights
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 557~564
This paper presents a watermarking algorithm for embedding visually recognizable pattern (Mark, Logo, Symbol, stamping or signature) into the image. first, the color image(RGB model)is transformed in YCbCr model and then the Y component is transformed into 3-level wavelet transform. Next, the values are assembled with pattern watermark. PN(pseudo noise) code at spread spectrum communication method and mutilevel watermark weights. This values are inserted into discrete wavelet domain. In our scheme, new calculating method is designed to calculate wavelet transform with integer value in considering the quantization error. and we used the color conversion with fixed-point arithmetic to be easy to make the hardware hereafter. Also, we made the new solution using mutilevel threshold to robust to common signal distortions and malicious attack, and to enhance quality of image in considering the human visual system. the experimental results showed that the proposed watermarking algorithm was superior to other similar water marking algorithm. We showed what it was robust to common signal processing and geometric transform such as brightness. contrast, filtering. scaling. JPEG lossy compression and geometric deformation.
A study on the spoken digit recognition performance of the Two-Stage recurrent neural network
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 565~569
We compose the two-stage recurrent neural network that returns both signals of a hidden and an output layer to the hidden layer. It is tested on the basis of syllables for Korean spoken digit from /gong/to /gu. For these experiments, we adjust the neuron number of the hidden layer, the predictive order of input data and self-recurrent coefficient of the decision state layer. By the experimental results, the recognition rate of this neural network is between 91% and 97.5% in the speaker-dependent case and between 80.75% and 92% in the speaker-independent case. In the speaker-dependent case, this network shows an equivalent recognition performance to Jordan and Elman network but in the speaker-independent case, it does improved performance.
Design of LQ-servo PI controller considering Weight
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 570~576
This paper proposed LQ-Servo PI controller by considering LQ-Servo structure as PI controller with a partial state feedback and concerns about the development of the flexible design algorithm by introducing weights to the design parameters of the previous LQ-Servo design method. the propose algorithm improves the matchings of the maximum and minimum singular values at high and low frequencies of the design loop transfer function as well as its loop shaping for performance.
Adaptive Line Echo Cancellation combined with the Different Bit-rate Speech Coders.
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 577~583
An efficient echo cancellation method, which controls the echo caused from the PSTN, is proposed. In our situation, the PSTN is connected to the mobile subscriber and the base-station which use different bit-rate CVSD(continuously variable slope delta modulation) coders and echo canceller is installed at the location of the base-station. By using the symmetry of the coder pairs. the proposed method shortens the echo pate length and reduces the nonlinear distortion inherent in the coders. And it is implemented in the decoded signal region, so fitted to the general-purpose DSP implementation. We also proposed a echo cancellation method using the combined bit-stream so as to implement without the multipliers onto the VLSI. It has an improved echo cancellation performance by reducing the high frequency noises in the coders. And it has an reduced complexity by reducing the excitation rate of the bit-stream.
Efficient ROM Size Reduction for Distributed Arithmetic
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 3B, 2000, Pages 584~591
In distributed arithmetic-based architecture for an inner product between two length-N vectors, the size of the ROM increases exponentially with N. Moreover, the ROMs are generally the bottleneck of speed, especially when their size is large. In this paper, a ROM size reduction technique for DA( distributed arithmetic ) is proposed. The proposed method is based on modified OBC( offset binary coding) and control circuit reduction technique. by simulations, it is shown that the use of the proposed technique can result in reduction in the number of gates up to 50%