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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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Volume 24, Issue 12B - Dec 1999
Volume 24, Issue 12A - Dec 1999
Volume 24, Issue 11A - Nov 1999
Volume 24, Issue 10B - Oct 1999
Volume 24, Issue 10A - Oct 1999
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Volume 24, Issue 9A - Sep 1999
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Volume 24, Issue 8A - Aug 1999
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Volume 24, Issue 7A - Jul 1999
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Volume 24, Issue 6A - Jun 1999
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Volume 24, Issue 5A - 00 1999
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Connectivity Evaluation for a Class of Fault-tolerant Shuffle Exchange Networks
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1807~1814
This paper considers connectivity-related reliability measures for a class of fault-tolerant shuffle exchange networks to characterize the degrading features over time in the presence of faulty switching elements. The mean number of connected input/output pairs, the mean number of survivable input are considered as connectivity measures. The measures for the unique-path shuffle exchange network(SEN) and its two fault-tolerant variants, extra-stage SEN(SEN+) and INDRA network are derived analytically, and then are compared with numerical experiments
A Estimation of Transmission Link Capacity using Statistical Multiplexing Model on Optical Access Networks
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1815~1823
This study investigates the problem of potential bottleneck on FTTC access networks. The link capacity for multiplexed stream using the 2-state MMPP source model is estimate on the assumption of a single VC per user. An analytic from between the cell loss rate and the effective bandwidth has been used to estimate an appropriate ling bandwidth varying the fraction of active users.
On Estimation of Redundancy Information Transmission based on Systematic Erasure code for Realtime Packet Transmission in Bursty Packet Loss Environments.
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1824~1831
In this paper, the data recovery performance of systematic erasure codes in burst loss environments is analyzed and the estimation method of redundant data according to loss characteristics is suggested. The burstness of packet loss is modeled by Gilbert model, and the performance of proposed packet loss recovery method in the case of using systematic erasure code is analyzed based on previous study on the loss recovery in the case of using erasure code. The required redundancy data fitting method for systematic erasure code in the condition of given loss property is suggested in the consideration of packet loss characteristics such as average packet loss rate and average loss length.
Design and Performance Analysis of BLSR/4 WDM/SHR in All-Optical Transport Network
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1832~1840
This paper proposed a network to implement all optical bidirectional BLSR/4 WDM/SHR allowing restoration in the event of a failure. The proposed network can provide a high degree of transparency using all-optical components with no electric implementation and effective failure restoration due to BLSR/4 WDM/SHR architecture. This paper also presented a genetic simulation model for the survivability analysis of the proposed BLSR/4 WDM/SHR under failure scenarios, the restoration performance of the proposed network is analyzed in terms of performance parameters such as propagation time, processing time, optical switch time.
Dilated Banyan Network Recirculation
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1841~1851
Banyan network has been widely employed as a basic building block for ATM switches. But the banyan network has very low routing capacity because of the internal blocking problem. Hence, a dilated banyan network has been used as one solution that can overcome the internal blocking problem. However, tremendous network capacity is wasted in the dilated network In this paper, we propose a dilated banyan network with deflection routing and recirculation mechanism to fully utilize the wasted capacity. The performance of the proposed switch is analysed under uniform traffic assumption. Numerical and simulation results show that the proposed switch yields a significant improvement of the maximum throughput as compared that of the pure dilated banyan network.
Performance Analysis of Voice over ATM using AAL2 based on Packet Delay Evaluation
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1852~1860
This paper studied performance of the AAL2 for variable rate real time services in ATM network with discrete-time simulation model. In this simulation, input parameters are packet fill delay for AAL2 PDU generation, guard time for ATM cell generation, burstness and number of channels. Though variation of the above mentioned parameters, we obtained end-to end delay variations and throughput, analyzed performance effect of the each parameter for voice packet service.
Performance Analysis of ISDN AO/DI Scheme with Multiople ON-OFF sources
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1861~1866
ISDN provides mB+1D channel to users. An AO/D1 scheme means D-channel can be used for a permanent low speed connection. When user needs more bandwidth for high speed transfer, the AO/D1 scheme automatically provide greater capacity in the shape of ISDN B-channels. In this paper, we analyze the performance of the AO/D1 scheme with multiple ON-OFF sources in ISDN. We consider multiple ON-OFF sources connected through mB+1D ISDN link. Without the AO/D1 scheme, the required bandwidth will be the sum of peak bandwidth of all sources. With the implementation of the AO/D1 scheme, the required bandwidth is reduced to what is really needed.
Laxity Decomposition Method for Scheduling Real-time Periodic Messages
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1867~1875
This paper presents a very unique and analytic method for scheduling messages routed through a non-blocking switch. The laxities of schedulable messages are decomposed and the laxity table is rearranged so that the packets to be scheduled in the next time instance are placed in the diagonal of the traffic matrix. And the modified MLF-SDR algorithm is performed on the table. We present some examples and simulation results which show that the success rate is very high, even when the size of which is large.
Characterization of Transmission Properties of Two Common Interior Walls at UHF Bands
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1876~1884
The next generation of wireless LAN AND PBX systems will make use of the unlicensecd band at 2.5 GHz. Deployment of these systems inside buildings requires and understanding of propagation characteristics within buildings. Because the wavelength is small compared to building dimensions, ray methods can be used to predict propagation, but they require knowledge of the transmission and reflection properties of walls. This paper reports on transmission measurements made at walls made of gypsum board on metal studs, and at concrete block walls using directive antennas. The measurements are found to give good agreement with theoretical results that account for the periodic nature of the wall structure.
Solution of higher order mode cutoff frequencies in TEM cells by Galerkin method
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1885~1894
The higher mode cutoff frequencies in Crawford TEM cells computed by the Galerkin method(GM) describe in this paper. The authors also report the half mode boundaries to solve not only the cut-off frequencies of symmetric TEM cells and those of asymmetric TEM cells. It is shown that the measured resonant frequencies of the present symmetric TEM cells and a designed asymmetric TEM cell are agreed with the calculated results.
Method of Momnets Solution for the Characteristics of a Disk-Loaded Cylindrical Dipole Antenna
Cho, Won-Seo ; Park, Kyu-Don ; Hwang, Ho-Jung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1895~1901
The characteristics of a disk-loaded cylindrical dipole (DLCD) antenna that determine its performance are analyzed by using the method of moments. The current integral equation that is considered with extended boundary condition is derived. Numerical results for the input impedance and radiation pattern of the antenna are presented. The antenna factor with the antenna gain is computed to check the possibility of using this antenna as the broadband antenna for the special case in such as electromagnetic compatibility testing. The comparisons of the computed results with measured data are made. These results will allow this antenna to be used with confidence in various applications.
A Content-Based Image Retrieval Technique Using the Shape and Color Features of Objects
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1902~1911
In this paper we present a content-based image retrieval algorithm using the visual feature vectors which describe the spatial characteristics of objects. The proposed technique uses the Gaussian mixture model(GMM) to represent multi-colored objects and the expectation maximization(EM) algorithm is employed to estimate the maximum likelihood(ML) parameters of the model. After image segmentation is performed based on GMM, the shape and color features are extracted from each object using Fourier descriptors and color histograms, respectively. Image retrieval consists of two steps: first, the shape-based query is carried out to find the candidate images whose objects have the similar shapes with the query image and second, the color-based query is followed. The experimental results show that the proposed algorithm is effective in image retrieving by using the spatial and visual features of segmented objects.
Motion-Compensated Layered Video Coding for Dynamic Adaptation
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1912~1920
In this paper, we propose a layered video coding scheme which can generate multi-layered bitstream for heterogeneous environments. A new motion prediction structure with temporal hierarchy of frames is developed to afford temporal resolution scalability and the wavelet decomposition is adopted to offer spatial acalability. The proposed scheme can have a higher compression ratio than replenishment schemes by using motion estimation and compensation which can further reduce the temporal redundancy, and it effectively works with dynamic adaption or errors using dispersive intra-subband update (DISU). Moreover, data rate scalability can be attained by employing embeded zerotree wavelet (EZW) technique which can produce embeded bitstream. Therefore, the proposed scheme is expected to be effectively used in heterogeneous environments such as the Internet, ATM, and mobile networks where interoperability are required.
Performance Comparison of Blocking Artifact Reduction Using a Block Boundary Region Classification
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1921~1936
In this paper, we analyze the blocking artifact in block transform-coded images and propose a classification algorithm which classifies each horizontal and vertical block boundary into four regions of EQ, BA, EE, and AE according to the characteristics of the blocking artifact. We also compare the performance of several blocking artifact reduction methods which can reduce blocking artifact in block transform-coded images well. As the blocking artifact reduction methods, the LOT, Kim's wavelet transform-based method, Yang's POCS, Paek's POCS, and Jang's CM have been selected. Experimental results show that each horizontal and vertical block boundary classified by using the proposed classification algorithm yields different characteristics of discontinuities due to the blocking artifact according to the classified region. It is also shown that the blocking artifact reduction methods using wavelet transform yield better performance over the other methods.
Simplification of 3D Polygonal Mesh Using Non-Uniform Subdivision Vertex Clustering
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1937~1945
In paper, we propose a 3D polygonal mesh simplification technique based on vertex clustering. The proposed method differentiates the size of each cluster according to the local property of a 3D object. We determine the size of clusters by considering the normal vector of triangles and the vertex distribution. The subdivisions of cluster are represented by octree. In this paper, we use the Harsdorff distance between the original mesh and the simplified one as a meaningful error value. Because proposed method adaptively determine the size of cluster according to the local property of the mesh, it has smaller error as compared with the previous methods and represent the small regions on detail. Also it can generate a multiresolution model and selectively refine the local regions.
Edge Preserving Image Compression with Weighted Centroid Neural Network
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1946~1952
A new image compression method to preserve edge characteristics in reconstructed images using an unsupervised learning neural is proposed in this paper. By the unsupervised competitive learning which generalizes previously proposed Centroid Neural Network(CNN) algorithm with the geometric characteristics of edge area and statistical characteristics of image data, more codevectors are allocated in the edge areas to provide the more accurate edges in reconstructed image. Experimental results show that the proposed method gives improved edge in reconstructed images when compared with SOM, Modified SOM and M/R-CNN.
Analysis and parameter extraction of motion blurred image
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1953~1962
While acquiring the image, the shaking of the image capturing equipment or the object seriously damages the image quality. This phenomenon, which degrades the clarity and the resolution of the image is called motion blur. In this paper, a newly defined function is introduced for finding the degree and the length of the motion blur. The domain of this function defined as Peak-trace domain. In The Peak-trace domain, the noise dominant region for calculating the noise variance and the signal dominant region for extracting the degree and the length of the motion blur are defined and analyzed. Using the information of the Peak-trace in the signal dominant region, we can find the direction of the motion regardless of the noise corruption. Weighted least mean square method helps extracting the Peak-trace more precisely. After getting the direction of the motion blur, we can find the length of the motion blur based on one dimensional Cepstrum. In the experiment, we could efficiently restore the degraded image using the information obtained by the proposed algorithm.
Performance Improvement Using the Adaptive Selection of H.263+ Negotiable Option Modes
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1963~1970
Researches in draft recommendation H.263 have been made in ITU-T LBC group to broaden its range of useful application and to improve its compression performance. The form of added and revised draft text of H.263 is informally known as “H.263+”. In this paper, we analyzed the characteristics of H.263+ negotiable option modes for four image classes. Based on the analysis results, we proposed the adaptive selection scheme of H.263+ option modes by using a scene change detector for a mixed image class. In case of using the proposed scheme, we obtained the 1.6dB improvement in PSNR compared to the basic mode of H.263, and the 0.4~1.0 dB improvement in PSNR compared to the fixed usage scheme of H.263+ negotiable option modes. In respect to used bits per frame, fewer bits are produced than the basic mode H.263 and the foxed usage scheme of H.263+ option modes.
A Video Traffic Model based on the Shifting-Level Process (Part I : Modeling and the Effects of SRD and LRD on Queueing Behavior)
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1971~1978
In this paper, we study the effects of long-range dependence (LRD) in VBR video traffic on queueing system. This paper consists of Part I and II. In Part I, we present a (LRD) video traffic model based on the shifting-level (SL) process. We observe that the ACF of an empirical video trace is accurately captured by the shifting-level process with compound correlation (SLCC): an exponential function in short range and a hyperbolic function in long range. We present an accurate parameter matching algorithm for video traffic. In the Part II, we offer the queueing analysis of SL/D/1/K called ‘quantization reduction method’. Comparing the queueing performances of the DAR(1) model and the SLCC with that of a real video trace, we identify the effects of SRD and LRD in VBR video traffic on queueing performance. Simulation results show that Markoivian models can estimate network performances fairly accurately under a moderate traffic load and buffer condition, whereas LRD may have a significant effect on queueing behavior under a heavy traffic load and large buffer condition.
A Video Traffic Model based on the Shifting-Level Process (Part II : An Efficient Analysis Method for SL/D/1/K Queueing System)
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1979~1985
In this paper, we offer an analysis method for SL/D/1/K queueing system, where the shifting-level (SL) process proposed in the part I of this study. Since an exact analysis of SL/D/1/K queueing system is very difficult, we propose an approximation method, where the queze sizes at input state transition epochs is quantized and thus the name 'quantization reduction method'. We provide the upper and lower bounds of the approximation for the system size distribution also, In addition, since the continuos version of well-known DAR(1) model is a kind of SL process with exponential correlation term only, the proposed method can be directly applied to the analysis of DAR(1)/D/1/K queueing system as well.
A Hierarchical Semantic Video Object Tracking Algorithm Using Watershed Algorithm
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1986~1994
In this paper, a semi-automatic approach is adopted to extract a semantic object from real-world video sequences human-aided segmentation for the first frame and automatic tracking for the remaining frames. The proposed algorithm has a hierarchical structure using watershed algorithm. Each hierarchy consists of 3 basic steps: First, seeds are extracted from the simplified current frame. Second, region growing bv a modified watershed algorithm is performed to get over-segmented regions. Finally, the segmented regions are classified into 3 categories, i.e., inside, outside or uncertain regions according to region probability values, which are acquired by the probability map calculated from an estimated motion-vector field. Then, for the remaining uncertain regions, the above 3 steps are repeated at lower hierarchies with less simplified frames until every region is classified into a certain region. The proposed algorithm provides prospective results in studio-quality sequences such as 'Claire', 'Miss America', 'Akiyo', and 'Mother and daughter'.
A Study on Blind Adaptive Interference Suppression for DS-CDMA systems
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 1995~2003
Since the cross-correlation function which is due to communication channel distortion or interference is not orthogonal, near far problem and multi-user interference are generated in the DS-CDMA system. Those problems degrade performance of the system so that the efficient algorithm to suppress the interference in the DS-CDMA system is required. In this paper, a blind adaptive interference suppressor using constant modulus algorithm is proposed. Simulation results present that the gain of SIR for the blind adaptive receiver is about 7[dB] at steady state over Gaussian channel in forward channel. The gain of noise to interference ration is about 4[dB] over Rayleigh fading channel, is about 11[dB] over multipath channels. Thus the proposed receiver has higher performance than a conventional receiver in the DS-CDMA system.
A Study on Blind Multiuser Detection using the Constant Modulus Algorithm for DS-CDMA Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 10B, 1999, Pages 2004~2010
This paper presents the blind multiuser detector using the constant modulus algorithm(CMA) to solve the near-far problem in DS-CDMA systems. The convergence property of the detector is compared with the conventional MOE(minimum output energy) detector by means of SIR(signal-to-interference ratio). The MOE detector needs both the spreading code of the users and the timing information, while proposed methods needs only information about the spreading code of users Simulation results show that the CMA-based detector is superior to the conventional blind MOE multiuser detector. For this, the BER performance was tested using different values of SNR and near-far ratio. The SIR is also investigated for different number of users in AWGN and Rayleigh fading channels. We have observed that the proposed blind multiuser detector performs better than conventional MOE multiuser detector.