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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
Performance evaluation of new curvature estimation approaches
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 881~888
The existing method s for curvature estimation have a common problem in determining a unique smoothong factor. we previously proposed two approaches to overcome that problem: a constrained regularization approach and a mean field annealing approach. We consistently detected corners from the perprocessed smooth boundary obtained by either the constrained eglarization approach or the mean field annealing approach. Moreover, we defined corner sharpness to increase the robustness of both approaches. We evaluate the performance of those methods proposed in this paper. In addition, we show some matching results using a two-dimensional Hopfield neural network in the presence of occlusion as a demonstration of the power of our proposed methods.
LDesign and implementation of a content-based image retrieval system using the duplicated color histogram and spatial information
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 889~898
Most general content-based image retrieval techniques use color and texture as retrieval indices. Spatial information is not used to color histogram and color pair based on color retrieval techniques. This paper proposes the selection of a set of representative in the duplicated color histogram, the analysis of spatial information of the selected colors and the image retrieval process based on the duplicated color histogram and spatial information. Two color historgrams for background and object are used in order to decide on color selection in the duplicated color histogram. Spatial information is obtained using a maximum entropy discretization. A retrieval process applies to duplicated color histogram and spatial to retrieve input images and relevant images. As the result of experiment of the image retrieval, improved color his togram and spatial information method hs increased the retrieval effectiveness more the color histogram method and color pair method.
A theoretical study on the demodulation for coherent optical communication system using DPSK
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 899~906
It is known that the Differential Phase Shift Keying (DPSK) modulation scheme in the coherent optical communication system is suitable for design of long-distance transmission system because its receiver performance is 3-5dB better than ASK and FSK. In this paper, we descrive a fundamental understanding of the effects of laser phase noise on the performance of coherent lighwave communication systems. Formulas are derived for the bit error rate in homodyne and heterodyne DPSK. Based on detailed mathematical analysis and estimates, we explain the following finding. DPSK can operates at rates only 300 times greater than the laser linewidth.
Analytical formula for decoding of images encoded using fractal algorithm proposed by monro and dudbridge
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 907~914
The conventional decoding procedure for the images encoded using fractal contractive transformation algorithms is performed by applying the transformations iteratively for an arbirary initial image. In this paper, we showed that the atractor image can be obtained analytically when the image is encoded using the fractal algorithm proposed by Monro and Dudbridge, in which the corresponding domain block for a range block is fixed. Using the analytical formula, we can obtain the attractor image without iteration procedure. Computer simulation results for various test images show that we can increase the image decoding speed by more than five times when we use the analytical formula compared to the previous iteration methods. Also we confirmed that the real time decoding by software on PD is possible for the moving picture with QCIF formats.
An error concealment technique using directional interpolation in block-based image compression
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 915~927
In this paper, we propose an error concealment technique using directional interpolation in block-based image compression. In the proposed method the edge direction is determined by finding the maximum correlation coefficients of boundary pixels of blocks neighboring the errored block in spatial domain. Then the errored block is interpolated linearly or bilinearly along the determined edge direction. The proposed method can conceal the block error, the macro block error, and the slice error adaptively. Also, the parameters for the directional interpolation are represented by closed forms. When applied to compressed images, the proposed method shows superior subjective and objective quality to conventional error concealment methods.
Extraction of singular points of fingerprint image using multiresolution directional information
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 928~938
We propose an algorithm for extracting singular points of fingerprint image using directional information. First, we extract the candidates of singular points using Poincare index in two(lower and higher) resolutional directional images. Then we remove the false singular points using smoothing technique from lower resolutional directional image. And finally we select the singular points in higher resolution corresponding to those in lower resolution. The possible missing points in lower resolution are found by computing Poincare index algong the proposed small curve. And the reliable points are selected from analysis around them. We also propose a method for segmentation of fingerprint as preprocessing step to enhance the computational speed and the performance of system.
The fuzzy transmission rate control method for the fairness bandwidty allocation of ABR servce in ATM networks
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 939~948
In this paper, we propose the new rate-based transmission rates control algorithm that allocates the fair band-width for ABR service in ATM network. In the traditional ABR service, bandwidth is allocated with constant rate increment or decrement, but in the proposed algorithm, it is allocated fairly to the connected calls by the fuzzy inference of the available bandwidth. The fuzzy inference uses buffer state and the buffer variant rate as the input variables, and uses the total transmission rate as a output variable. This inference a bandwidth is fairly distributed over all ABR calls in service. By simmulation, we showed that the proposed method improved 0.17% in link effectiveness when RIF, RDF is 1/4, 38.6% when RIF, RDF 1/16, and 82.4% when RIF, RDF 1/32 than that of the traditional EFPCA.
Analysis of a user detection scheme in nakagami interferenence
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 949~955
Detection of the existence of a desired user is considered in this paper. We assume that the signal to noise ratio is high enough for us to ignore the effects of noise compared with those of the interference by other users. The inter-user interference and user signals are modeled by the Nakagami model. An observation model for this situation is proposed, the locally optimum test statistic is derived under the model, and the asymptotic performance of the locally optimum detector is compared with of the envelope detector. We show that the locally optimum detector performs better than the conventional envelope detector.
Implementation of real-time free-space optical interconnection using spatial light modulator
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 956~966
Dynamic free-space optical interconnection system is experimented by a holographic crossbar with single-state switching architecture. For dynamic operation, electrically addressed liquid-crystal spatial light modulator and diffraction gratings are used in place of passive holograms of matrix-matrix crossbar. Diffraction gratings are consisted of regular cells which have different phase delays. This pixelated phase grating array displayed on SLM(Spatial Light modulator) deflects an input beam toward a wanted direction or splits an input beam into many beams and then steers them to desired positions. Through the experimental results, free-space optical interconnection is dynamically perfomed using a computer, SLM and phase diffraction gratings.
The K-band push-push type miniaturized haripin resonator oscillator
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 967~973
In this paper, the designed and fabrication of a K-band push-push oscillator using miniaturized hairpin resonator have been presented. One experimenal oscillator has been designed and fabricated for K-band point-to-point operation. the miniaturized harpin resonator has been analyzed theoretically and simulated by MPIE(Mixed Potential Integral Equation) method. With this results, the analysis of hairpin resonator which coupled microstrip line has been carried out with transmission-mode using this results. an optimized output matching network for the suppression of the fundamental and the 3rd order harmonic was acquired by using a nonlinear analysis method. The fabricated oscillator shows the output power of -2.28dBm, the fundamental frequency suppression of -19dBc, the 3rd order harmonic suppressionof -24dBc and 0.33 percent effiiency at 22.8GHz. The experimental outputs are in good agreement with the theoretical and simulated results.
A study on the design technologies for the 1-state 23GHz LNAs
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 974~980
The 23GHz 1-state LNA was designed by using MPIE numerical analysis and conventional design EEsof softwares. The circuit was designed using conventional tools but analyzed and modified by using numerical MPIE tools. he matching sections was designed with parallel coupled filter-type, which gives impedance matching and DC blocking and has small discontinuities. THe FET chip is directly attached to the graound metal. The designed LNA gives 5.8dB gain and 2.5dB noise figure withoug considering the loss and impedance shift of connectors that degenerate the gain and noise figure considerably. this results gives very promising characteristics for our design process and matching schemes and fabrication technologies.
A study on the active phased array antennas with slotline coupling
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 981~989
In this paper, the 5-element active phased array antennas coupled through slotline between elements are designed and fabricated. A recent studies on the active phased array antennas using the transmission line coupling which can be designed to provide strong coupling and the appropriate coupling phase. But this sturucture has limitation of expanding in two dimensions for planar active phased array antennas and distortion of the radiation pattern caused by coupling network. Thus our work proposes the slotline coupling structure asthe broadband coupling network for the active phased array antenna. In experiment, 5-elements active phased array antenas have steering range from -30.deg. to 20.deg. off broadside as the free-running frequencies of end elements are controlled. The overall results show that the proposed slotline coupling structure is suited for the coupling network in the actie phased array antenna system. And the proposed coupling structire solves the expansion problem and eliminates the distortion of the radiation pattern caused by the spurious radiation of the transmission line coupling network. Thus thiscan be expanded to two dimensional coupling network for the planar active phased array antenna system.
Implementation and performance assessment of high-rate digital subscriber lind(HDSL) interface function under ATM
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 990~1006
This paper describes an interface function and its performance assessment for high-bit-rate digital subscriber line (HDSL) under ATM. The interface of HDSL function of ATM system was achieved by HDSL subscriber physical layer board assembly(HSPA) which was modeled as design standard for ATM. We have presented a new worst case of subscriber line conditions from existing results of investigations on impairments such as crosstalk, impulse noise, longitudinal, power line noise and others. We have measured the maximum service loop length available by HDSL, and found that HSPA, at a 2.048Mbps data transmission, is possible within a carrier serving area(CSA) under the worst case loop noise conditions at an error rate or 10
on a two coordinated unshielded twisted pairs in the presense of impairments. We conclude tht, in terms of a performance-per-lin simulator, the HSPA is an excellent candidate for HDSL implementation under ATM.
Telecommunication network surivability evaluation model
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1007~1017
The existing survivability measure is defined as the only ratio of survival traffic volume on the given traffic demand. In this paper we suggest a new network survivability evaluation model. Sinceit depends on the importance of traffic, we can evaluatethe affect of telecommunication disaster. With the suggested evaluation model we formulate optimization models for restoration paths and traffic assinment on them. The optimization models are represented as mixed integer programming problems, which are difficult to find exact solutions. We develop heuristic algorithms according to the optimization models and apply them to an example network with 10 nodes and 17 links.
A study on interoperability mechanism of ABR/ABT capability in ATM public networks
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1018~1025
In this paper, we propose the interworking and emulation methods for the interoperability of ABR/ABT capability and algo propose the BCR Re-negotition with State-Dependent (BRSD) mechanism based on the common buffer with two thresholds and the EBCN method when public network hs the ABT capability. As BRSD mechansism has one common buffer for all ABR connectiona and BCR re-negotiation request according to the threshold, it can reduce the queue length and the frequency of ABT BCR re-negotiation. Using EBCN method, BRSD mechanism can prevent the continuous increasing of queue length in the emulation method with the CI bit setting of the ABR performance of the BRSD mechanism in the view poits of the masimum queue length, bandwidth utilization and ABT-BCR re-negotialtion frequency trough the simulation.
A study on the phoneme recognition using radial basis function network
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1026~1035
In this paper, we studied for phoneme recognition using GPFN and PNN as a kind of RBFN. The structure of RBFN is similar to a feedforward networks but different from choosing of activation function, reference vector and learnign algorithm in a hidden layer. Expecially sigmoid function in PNN is replaced by one category included exponential function. And total calculation performance is high, because PNN performs pattern classification with out learning. In phonemerecognition experiment with 5 vowel and 12 consant, recognition rates of GPFN and PNN as a kind of RBFN reflected statistic characteristic of speech are higher than ones of MLP in case of using test data and quantizied data by VQ and LVQ.
Fast exponentiation with modifed montgonmery modular multiplication
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1036~1044
We modify the montgomery modeular multikplication to extract the common parts in common-multiplicand multi-plications. Since the modified method computes the common parts in two modular multiplications once rather than twice, it can speed up the exponentiations and reduce the amount of storage tables in m-ary or windowexponentiation. It can be also applied to an exponentiation mehod by folding the exponent in half. This method is well-suited to the memory limited environments such as IC card due to its speed and requirement of small memory.
Design and implementation of the synchronization circuit for OFDM system without synchronization preambles
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1045~1057
In this paper, we propose an algorithm of block synchronization that uses data withoug synchronization preambles. Block synchronization systems is implemented using the DSP chip employing the proposed algorithm. The data spread of the DFT blocks is proportional to the offset of DFT block and this information is used to achieve the block synchronization in the receiver. The initial bleock synchronization and the clock synchronization between transmitter and receiver are achieved using the early-late removal of the guard interval. The hardware implmentation is carried out using the DSP chip TM320C30 to verify the proposed block synchronization algorithm with the data rate 1200bps. The DSP chip calculates the spread of the 128 complex FFT in the receiver with the system clock 30MHz. It is believed that the proposed synchronization algorithm can be used in the design of OFDM block synchronization with the high processing DSP chip.
On the chain condition for preparata codes over
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1058~1063
Though the Preparata code of length 8 over
satisfies the chain condition, the Preparata code of length 16 or 32 over
does not satisfy the chain condition. In this paper we show that the Preparata code of length
does not satisfy the chain condition for m=4, 5, 6 and 8 by investigating relations between weight hierarchy and chain condition.
Every-other-row-connecting bilayered shufflenet for WDM multihop lighwave networks
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1064~1074
In this paper we propose an every-other-row-connecting bilayered ShuffkeNet for optical WDM(wavelength division multiplexing) multihop networks. We calculate the diameter and the average number of hops of the proposed every-other-row-connecting bilayered ShuffleNet. Using the result, we also calcuate throughputs and delays of the proposed topology, which show higher efficiencies compared to the conventional ShuffleNet, the bilayered ShuffleNet and asymmetric bilayered ShuffleNet.
A channel assignment scheme for reducing call blocking rate in DS-CDMA cellular systems
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1075~1082
In this paper, we propose a channel assignment scheme for reducing call blocking rate in a base station(BS) of DS-CDMA cellular systems. The proposed scheme can e applied to the case where the capacity of reverse radio link is enough, but not are the available traffic channels performing the digital modulation and demodulation functions between a mobile station and the base station. The proposed scheme takes advantage of the feature of soft handoff in which a mobile station keeps its communication link even if one of the two communication links is released. The scheme estimates the mean and variance of the received power level measured at the base station before assigning a traffic channel for a new call request. The BS makes decision based on the estimated balues whether the new call request will be accepted or not. If it is decided that the capacity of reverse radio link is enough, but all traffic channels are not available, then the BS increases the soft handoff parameter T_DROP to release the traffic channels of mobile stations loactedin soft handoff area. The BS assigns the released traffic channel to anew call or a handoff call. The performance of the proposed channel assignment scheme is evaluated by computer simulation. The results show that the call blocking rate for new calls and handoff calls is reduced.
The channel coding algorithm for the ATM cell QoS improvement in statellite B-ISDN/ATM network
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1083~1096
To implement satellite B-ISDN/ATM network, it needs to gurantee reliable transport via satelite in the poor BER environment. So, it requires to use channel coding (FEC:Forward Error Correction) schemes for improvement of BER performance, but these coding effects evoke burst errors and degradation of the QoS. Therefore we have to investigate new algorithm that compensates these weaknesses. We consider convolutional coding and concatenated coding among FEC schemes as FEC for satellite transmission and choose different compensational algorithm by the error characteristics of the using type of FEC. In using concatenated coding, this paper proposes the satellite system structure for interconnection to the terrestrial network and proposes the channel coding algorithm for improvement of transmission performances. We execute performance evaluation of the proposed algorithm by computer simulation. In detail, we propose 4 types of application ATM cell to the block coding(Reed-Solomon) and propose the new 55 byte ATM cell that enforces the error correction capability of cell header by the BCH coding. Then we propose the outer interleaverand the cell unit interleaver that evoke maximum coding effect of BCH code.
CQ importance sampling technique for the rician fading channel
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1097~1106
Most works on importance sampling (IS) as an efficient evaluation technique havd been done in an additibe white gaussian noise channel (Awgn). In this paper we propose a CQ(conventional importance sampling and quasi-translantion) IS technique for the mobile radio channel modeled as Rician fading, and analyze the IS estimator's variance to determine optimum IS parameters and the minimum number of run times. Reference showed that CIS technique has a poor performance for systems with meories, but it is shown that the CIS technique can be improved by combining with quasi-translation technique even for systems with memories. Here the CQ IS technique modifies the variance of additive noise and also performs quasi-translation for the fading distribution. We determine the optimum IS parameters of the proposed CQ IS estimator and whow that the simulation gains are about 10
for the mobile communication systems with memories in case of the expected BERs 10
An error concealment method using projections onto the overcomplete basis
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1107~1115
In this paper, we propose an error concealment method to recovre damaged block-based image coding schemes. Channel errors during transmission of image data such as bit errors or cell loss result in damaged image blocks in the reconstructed images. To recover damaged blocks is to estimate them using the correctly received or undamaged neighborhood information. In the proposed method, an overcomplete basis for a large block containing a damaged block at its center is introduced and damaged blocks are recovered by sequentially projecting the known neighborhood information onto the overcomplete basis function. Computer simulations show that the proposed algorithm outperforms the conventional method in subjectie recovery qualities as well as objective ones.
A study on improvement of leaky bucket UPC algorithm in ATM networks
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 5, 1997, Pages 1116~1125
In this paper, the modified UPC(Usage Parameter Control) algorithm is proposed. The proposed UPC algorithm is based on Leakey Bucket algorithm and adds the characteristics of the jumping window algorithm for monitoring the average bit rate. The proposed algorithm let a cell, which is tagged by Leaky Bucket algorithm, pass through the network, if the network does not violate the average bit rate. The measuring method of window mechanism like jumping window. This paper supposes On/Off traffic source model of rthe performance evaluation and analysis of the proposed algorithm. Therefore, as simulation results, the proposed algorithm acquires more reduced results of the cell loss rate and bucket size than the Leaky Bucket algorithm.