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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 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
Volume 25, Issue 12 - 00 2000
Volume 25, Issue 10 - 00 2000
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다중채널 선형등화기를 이용한 혼합 TDMA/CDMA 시스템의 성능 개선
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1273~1273
A Study on the Channel Assignment Scheme on Enhancing New Call Service in Wireless Network
임영훈 ; 배성수 ; 오용환 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1282~1282
In this papaer, we propose a Fractional Channel Reservation(FCS) scheme to satisfy a desired handoff dropping probability and to reduce the blocking probability of new calls using mobility characteristics and incoming handoff rate in mobile communication networks. When the ration of the handoff arrival rate is less then the ratio of the new call arrival rate, the proposed scheme is capable of determining the number of the guard channels which can guarantee the Quality of Service(QoS) in terms of the request handoff dropping probability and allocating dynamically the wireless channels the new calls according to the rest of the guard channels to reduce the new call blocking probability. Also we perform mathematical analysis and simulation to evaluate the performance of proposed scheme, and compare to conventional guard channel scheme in terms of dropping probability, blocking probability, and the utilization efficiency of wireless channels.
Performance Analysis of MAP Algorithm by Robust Equalization Techniques in Nongaussian Noise Channel
소성열 ; 이창범 ; 최상호 ; 김영권 ; 송홍종 ; 정부영 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1290~1290
Turbo Code decoder is an iterate decoding technology, which extracts extrinsic information from the bit to be decoded by calculating both forward and backward metrics, and uses the information to the next decoding step. Turbo Code shows excellent performance, approaching Shannon Limit at the view of BER, when the size of Interleaver is big and iterate decoding is run enough. But it has the problems which are increased complexity, and delay and difficulty of real-time processing due to Interleaver and iterate decoding. In this paper, it is analyzed that MAP(maximum a posteriori) algorithm which is used as one of Turbo Code decoding, and the factor which determines its performance. MAP algorithm proceeds iterate decoding by determining soft decision value through the environment and transition probability between all adjacent bits and received symbols. Therefore, to improve the performance of MAP algorithm, the trust between adjacent received symbols must be ensured. However, MAP algorithm itself, can not do any action for ensuring, so the conclusion is that it is needed more algorithm so to decrease iterate decoding. Consequently, MAP algorithm and Turbo Code performance are analyzed in the nongaussian channel applying Robust equalization technique in order to input more trusted information into MAP algorithm for the received symbols.
The Prediction Modelling of Traffic Flow with Time-Variable Non-Linear Characteristic in ATM Network
김윤석 ; 진용옥 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1299~1299
In B-ISDM, to realize ATM, the optimum control method of multi-media traffic must be proposed. Because there is not the traffic model of multi-media to make clear, the realization of optimum ATM congestion control is very difficult. In this paper, the traffic model is assumed to be slowly time-variable non-linear function, and for real-time prediction of it, new model which is composed with parallel triple neural networks is proposed. And the simulation to predict assumed ATM traffic is executed. From the result, it's capability is shown that the proposed neural network model can be used in ATM congestion control.
The Quality Loss of a X-Band Transmitter on the LEO Satellite
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1306~1306
The quality loss of a X-band transmitter has been derived by means of MC simulation. The transmitter as a payload of LEO(Low Earth Orbit) satellite is capable of the down transmission the image data of hundreds Mbps generated from the Electro-Optical Instrument in real time. The parameters such as data asymmetry, amplitude unbalance, phase unbalance, wave shaping and channel interference are included in the quality loss simulation. Assuming that normally distributed gaussian noise is simply added to the channel, the quality loss of 0.7 dB has been obtained through this simulation based on a 95% confidence interval. The obtained quality loss can be applied to the link budgets as an additional loss item.
Performance Analysis Turbo Codes for LEO Satellite Communication Channel
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1313~1313
Performance analysis of noncoherent satellite DS-CDMA system with orthogonal signals
안준기 ; 조용훈 ; 김환철 ; 홍인기 ; 황금찬 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1322~1322
In this paper, we compare the performances of noncoherent DS-CDMA system where orthogonal code is used for identifying the user to reduce multiple access interference or for M-ary orthogonal signaling to improve the performance of demodulation. The effects of M-ary orthogonal signaling on the noncoherent demodulation is investigated and compared with one of coherent demodulation. The analysis results show that M-ary orthogonal signaling gives better performance than quasi-synchronous orthogonal scheme for a moderate number of users when the processing gain is 128 over AWGN channel. In addition, when the number of user is 41, M=64 orthogonal signaling has a similar performance to the quasi-synchronous orthogonal scheme at the BER of 10-2 when the time misalignment between channels is within 1/2 chip and M=256 orthogonal signaling always outperforms the quasi-synchronous orthogonal scheme. Start after striking space key 2 times.
Design of a High Speed Asymmetric Baseband MODEN ASIC Chip for CATV Network
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1332~1332
Realtime/Non-realtime Multimedia Traffic Transmission in cdma 2000
이종찬 ; 이기성 ; 이근왕 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1340~1340
The international mobile telecommunication-2000(IMT-2000) system can support not only the non-realtime multimedia traffic such as data, image but also the realtime multimedia traffic such as voice, video. In the paper, we propose multicode allocation and handoff schemes for efficient transmission of realtime and non-realtime data in cdma2000. In those schemes, the bandwidth of target cell is reserved based on moving direction of mobiles to support QoS of realtime multimedia data, and the reserved bandwidths is used by the non-realtime mobiles of the target cell unitl the mobiles want to perform handoff. Our framework is able to guarantee QoS continuity of realtime multimedia data and carries the maximum number of subscriber. System performance is evaluated and compared with conventional scheme considering transmission delay, channel utilization and blocking probability by computer simulation.
Traffic analysis of the CDMA base station with repeaters using time delay devices
조욱 ; 진용옥 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1348~1348
The paper contributes to a traffic analysis for the CDMA cellular base station with repeater which are operated in a cell site. Usually the repeaters' traffic of the CDMA cellular system hardly could be separated from that of the base station, because the links of the repeaters are divided from RF circuits of the base station. The paper introduces a traffic measuring method that separates the traffic of repeaters from that of the base station using time delay device. To get general results, we use a single BTS(Base station Transceiver Subsystem) with three repeater as well as a single BTS with a single repeater. Then we proved that the traffic of the repeaters could separate from that of the base station clearly.
A New CDMA Uplink Channel Structure and DBCE Detection Scheme Using Staggered Burst Pilot
나종래 ; 이창수 ; 강양기 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1359~1359
A new coherent detection scheme with data based channel estimation(DBCE) for CDMA/BP (staggered burst pilot in parallel) channel structure is proposed. Because the pilot burst initiates DBCE operation periodically, it is shown to be remarkably stable to Gaussian noise and Doppler shift with proper parameter settings. In our own system parameter settings, there is negligible loss (0.068 dB) in
by the introduction of the burst pilot. When compared with an ideal coherent detection, the required
on Doppler shift corresponding to the speed of 160Km/H is degraded less than 2.0 dB. The burst pilot can be implemented without complexity even though some extra correlators are needed for DBCE. This improvement is superior to the previously coherent CDMA detectors with external or internal pilot.
Codesing of IS-95 based CDMA Searcher
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1368~1368
Analysis of ISUP signalling Delay in Common Channel Signaling System
박철근 ; 정태욱 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1377~1377
As all delays resulting from the signaling network directly affect the response time of network management activity, all control informations have to be transported most efficiently. It is very important to know the performance of the signaling system not only because of smooth network operation but also because of efficient engineering of signaling networks. In this paper, we analyzed mean queueing delay of signaling link for ISUP signaling messages in common channel signaling system by using
/D/1 batch arrival queueing system. This is because we modeled arrival process of the signaling messages as batch arrival process considering that many kinds of signaling messages are generated at short intervals when a call requests a connection. Analysis was carried out considering different call processing scenario based on ITU-T specification. We also described the numerical results from the different types of queueing models.
The Design Of Improved Information Security System based on SSL(Secure Socket Layer) For Providing Secure Communication Services
유성진 ; 김성열 ; 정일용 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1387~1387
The SSL(Secure Socket Layer) protocol is one of the mechanism widely used in the recent network system. The improved information security mechanism based on the SSL is designed in this paper. There are important four information security services. The first is the authentication service using the Certificate offered from the SSL(Secure Socket Layer), the second is the message confidentiality service using the DES encryption algorithm, the third is the message integrity service using Hash function, and the fourth is Non-repudiation service. Therefore, information could be transferred securely under the infromation security mechanism including Non-repudiation service especially designed in this paper.
An Adaptive Distributed Wavelength Routing Algorithm in WDM Networks
이쌍수 ; 정한유 ; 서승우 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1395~1395
In this paper, we propose a heuristic wavelength routing algorithm for IP datagrams in WDM(Wavelength-Division Multiplexing) networks which operates in a distributed manner, while most previous works have focused centralized algorithms. We first present an efficient construction method for a loose virtual topology with a connectivity property, which reserves a few wavelength to cope with dynamic traffic demands properly. This connectivity property assures that data from any source node could reach any destination node by hopping one or multiple lightpaths. We then develop a high-speed distributed wavelength routing algorithm adaptive to dynamic traffic demands by using such a loose virtual topology and derive the general bounds on average utilization in the distributed wavelength routing algorithms. Finally, we show that the performance of the proposed algorithm is better than that of the FSP(Fixed Shortest-Path) wavelength routing algorithm through simulation using the NSFNET and a dynamic hot-spot traffic model, and that the algorithm is a good candidate in distributed WDM networks in terms of the blocking performance, the control traffic overhead, and the computation complexity.
Distributed Wavelength Assignment Algorithm in WDM Networks
이쌍수 ; 이창형 ; 서승우 ; 장문종 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1405~1405
In this paper, we propose an efficient dynamic wavelength assignment algorithm in distributed WDM (Wavelength-Division Multiplexing) networks without wavelength conversion. The algorithm tries to assign a locally-most-used wavelength distributedly on a fixed routing path. We first formulate our algorithm by using the concept of a sample space which consists of optical filbers connected to nodes on a routing path of a lightpath to be assigned a wavelength. In particular, we analyze the blocking performance mathematically as compared with that of the most-used (MU) wavelength assignment algorithm previously proposed for WDM networks under centralized control. We also obtain numerical results by simulation on the blocking performance of other centralized/distributed wavelength assignment algorithms as well as our algorithm using the M/M/c/c dynamic traffic model. Consequently, we show that analytical results match simulation results and that our algorithm is efficient in distributed WDM networks in terms of blocking performance, control traffic overhead and computation complexity.
A Study on Efficient Transmission Rate Control of ABR Traffic in ATM
정명수 ; 김남희 ; 김변곤 ; 전병실 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1413~1413
In this paper, we analyze previous flow control algorithm for serving ABR traffic, and then propose the algorithm which calculate fair transmission rate and control efficiently ABR traffic using VS/VD switch which has an effect on WAN environment with long delay. For getting the transmission rate, the proposed algorithm use FMMRA as ER scheme which calculate exactly the fair share. And. in large delay state, we can obtain fair cell sharing by calculating transmission rates which obtained by transmitted queue length information of VD to VS for serve and drain cell in queue Through the computer simulation, we evaluate the performance of proposed algorithm. According to the results, the proposed algorithm shows good performance.
Analysis of S-CDMA Technique for Cable Modem Upstream Channel
김기윤 ; 이형근 ; 김판수 ; 조병학 ; 최형진 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1422~1422
S(Synchronous)-CDMA is a new modem technology applicable to the upstream channel for high speed multimedia using CATV networks. In this paper we analyze the transmitting and receiving process of S-CDMA scheme based on Terayon patent and derive bit error probability of S-CDMA and TDMA scheme in the ε-mixture impulse noise model which appropriately reflects impulse noise characteristics of upstream channel by using various parameters. This analysis results are a good match with the simulation results. We also compare Eb/No gain performance of S-CDMA with TDMA in 16, 32, 64 QAM.
Cell-interleaved VC merging scheme for multipoint-to-multipoint communication in ATM network
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1431~1431
Automatic Protection Switching Schemesfor Network Survivability in ATM-PON Networks
김영구 ; 박순홍 ; 이동춘 ; 조용환 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1441~1441
There are two of protection switching : a) automatic switching and b) forced switching. The switching mechanism is generally realised by OAM functions, therefore, the required OAM information fields should be reserved in the PLOAM cells. This paper proposes an unidirectional and a bidirectional protection switching method and potential advantages. The unidirectional protection switching method can be faster than the bidirectional method because the unidirectional method does not require an APS protocol for protection switching. The bidirectional protection switching method uses APS K1 byte and K2 byte, which is included in octets of a PST message through downstream of upstream PLOAM cells, for protection switching. As making comparisons between the unidirectional and the bidirectional protection switching method, this paper proposes an effective constructing method for ATM-PON network.
A unifying solution method for logical topology design on wavelength routed optical networks
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1452~1452
Design of Symmertrical Slot-Coupled Back-to-Back Microstrip Array Antenna
김태현 ; 전계석 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1511~1511
A new slot-coupled back-to-back microstrip array antenna is proposed for using in the IMT-2000 base station or repeater antenna. This antenna is composed of symmetrical SSAIP(Strip, Slot, Air, Inverted Patch). It has bidirectional radiation pattern in horizontal plane and 22.5° main beam squint in vertical plane. The analysis is based on the cavity model and the design is achieved using Ensemble. Experimental results for the radiation pattern and the return loss have shown that the direction of the main beam is about 21° and the impedance bandwidth is approximately 22.9% . Thus the proposed antenna is able to operate over both uplink and downlink frequencies in IMT-2000.
Optimum Design of High Speed Transmission SMF Link Using DCF
김용범 ; 이용원 ; 이명문 ; 유진태 ; 이상록 ; 주무정 ; 박진우 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1518~1518
This paper proposes an optical transmission link design method based on an optimum compensation scheme using dispersion compensating fiber (DCF) so that high-speed long-distance optical transmission would be possible over the conventional standard single mode fiber (SMF) link. The proposed design method provides the maximized transmission distances according to the signal speeds where the amplifier spacing and repeater spacing are optimized wit respect to self-phase modulation(SPM) due to fiber nonlinearity and amplified spontaneous emission (ASE) noises caused by optical amplifies. It is also shown that there exists an optimum input signal power range balancing the effects of ASE noise and SPM for the given amplifier spacing and repeater spacing.
Analysis of a transmission line on Si-based lossy structure using Finite-Difference Time-Domain(FDTD) method
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1527~1527
Basically, a general characterization procedure based on the extraction of the characteristics impedance and propagation constant for analyzing a single MIS(Metal-Insulator-Semiconductor) transmission line is used. In this paper an analysis for a new substrate shielding MIS structure consisting of grounded cross-bars at the interface between Si and SiO2 layer using the Finite-Difference Time-Domain (FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics a shielding structure consisting of grounded cross bar lines over time-domain signal has been examined. The extracted distributed frequency-dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor have been examined as functions of cross-bar spacing and frequency. It is shown that the quality factor of the transmission line can be improved without significant change in the characteristic impedance and effectve dielectric constant.
Chracteristics of Wavelength Shift in Fiber Ring Laser Tuned by Polarization Control
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1534~1534
Performance Analysis of Optical SCM Link System for CDMA RF Signal Transmission
유진태 ; 최영우 ; 김용범 ; 이명문 ; 이용원 ; 박진우 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1542~1542
Fiber optic link systems based on SCM scheme are widely used as efficient and economic RF signal links between base station and a central station in mobile communication networks. However, its performance can be seriously limited depending on the operational conditions of not only the optical transmission system but also the wireless link in various environments. In this paper, we propose an analytic model for performance analyses of the SCM fiber optic link for CDMA RF signal transmission in various link environments. We present optimal operational conditions taking account of the nonlinear effects of the optical transmission system, and the multiple access interference produced at the wireless link. It has been shown through the BER analyses in this paper that the selection of optical modulation index of the SCM fiber optic links can be found optimally to minimize the fiber optic link noises and intermodulation distortion due to LD.
A Study on the transducer development and multi-point signal and its directivity detection of FBG(Fiber Bragg Grating) hydrophone
김경복 ; 곽계달 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1551~1551
In the using of FBG developed in home land we design and manufactured three types of FBG sound transducers the first in Korea. On FBG transducers manufactured we made an demonstrated on respective frequency response peculiarties in the water and analyzed the special characters. As the experimental result on frequency response peculiarities we made t possible underwater acoustic detection on C type to maximum 18kHz, And for the purpose of realization on multi-point signal detection on wide scope in the water in the using of WDM(Wavelength Division Multiplexing) method and passive band-pass filter system established arrays system and succeeded in multi-point underwater acoustic signal detection to the frequency 1.3KHz out of the two B type FBG transducers. Additionally it would be possible directivitydetection for the objects of its source as the intensity of detection signal varies with the sound source's direction and angle. From now on we prepared a new moment on the practical used study on FBG hydrophone.
A Tone Detector USing Cascaded Nonlinear Energy Trackers
황성수 ; 이용환 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1563~1563
Teager-Kaiser algorithm that can track the energy of tone signals with simple nonlinear operations, has been applied to detection of tone signals closely spaced in frequency. The performance of the previous detector depends upon the performance of internal filters. An improved scheme is proposed in this paper by employing the nonlinear energy trackers in cascade. The proposed detector is analytically designed and verified by computer simulation. It shows that the new detection scheme improves the detection performance while reducing the implementation complexity.
Performance analysis of multi-carrier CDMA system using an orthogonal pair of quadrature filter banks
이재철 ; 최재호 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1570~1570
A quadrature pair of filter banks that are composed of a pair of cosine and sine modulated filter banks is applied to MC-CDMA data transmultiplexing in the view point of mitigating inter-channel interferences. Exploiting superior capabilities of wavelet properties in composing the filter banks,the proposed scheme is capable of compromising inter-channel interference problems better than the conventional DFT-based MC-CDMA due to superior subchannelization effects. To verify the behavior of our proposed MC-CDMA system based on the quadrature filter banks, the reverse-link bit error rates with respect to signal-to-noise ratio under Rayleigh fading and additive white Gaussian noise channel environments are computed. The results show an improved system performance over the conventional MC-CDMA in the view point of minimizing interference effects.
Noise Figure Analysis of IMT-2000 Receiver system Based on CDMA
이철희 ; 박종안 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1579~1579
This paper presents the properties of the RF part in the receiving system based in IMT-2000 terminal technology. It mainly discuss the RF parameter performance of the receiving system for mobile telecommunication comparable to IS-98A and J-STD-018 specifications of commercially available CDMA and PCS, and is to anticipate the processing gain of the IMT-2000 receiving system, processing gain according to data processing rate, and terminal noise figure according to processing gain, relationship between noise figures according to Eb/Nt, Ioc. It is performed by such analysis method as CDMA and PCS receiving systems. Transmission bandwidth is n×1.25 MHz(n=1, 3, 6, 9, 12) which is recommended by Qualcomm and NTT, the leading company in cdma 2000. Data transmission rate of IMT-2000 is classified into three cases as in moving vehicle environment of 144Kbps, outdoor pedestrian environment of 384Kbps, and indoor office environment of 2Mbps
Image restoration by Adaptive Regularization Considering the Edge Direction
김태선 ; 이태홍 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1588~1588
To restore image degraded by out-of-focus blur and additivie noise a regularized iterative restoration is used. In concentional method, regularization is usually applied to all over the image without considering the local characteristics of image. As a result, ringing artifacts appear in edge regions and the noise amplification is introduced in flat regions. To solve this problem we propose an adaptive regularization iterative restoration using directional regularization operator considering edges in four directions and the regularization operator with on direction for flat regions. We verified that the proposed method show better results in the suppression of the noise amplification in flat regions, and introduced less ringing artifacts in edge regions. As a result it showed visually better image and improved better ISNR further than the conventional methods.
An Image coding Scheme Using The Correlation of VQ Indices In Wavelet Domain
황재호 ; 홍충선 ; 이대영 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1596~1596
In this paper, an image coding scheme using the correlation of neighboring VQ indices in wavelet domain is proposed. The codewords in each sub-codebook are reordered in ascending order according to their energy in order to increas the dependency of the indices. And the relative adresses of the reordered indices are transmitted to a receiver instead of to absolute addresses. LBG algorithm is used for obtaining a multiresolution codebook and PNN using k-d tress used for generating its initial values. Our experimental results show that the proposed coding scheme outperforms JPEG and an ordinary wavelet-VQ method at low-bit rates in terms of PSNR.
An Improved Three-Step Search Algorithm for Block Motion Estimation
홍원기 ; 오태명 ; 고성제 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1604~1604
The three-step search (TSS) algorithm for block motion estimation has been widely used in real-time video coding due to the simplicity of the algorithm significant reduction of computationl cost and good performance. In this paper an improved three-step search (ITS) algorithm is proposed to improve the performance of the TSS algorithm. Simulation results show that in terms of motion compensation errors the proposed ITSS outperforms some popular fast search algorithms while it has the lower computational complexity.
Design of Cryptographic Coprocessor for SEED Algorithm
최병윤 ; 서정욱 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1609~1609
In this paper a design of cryptographic coprocessor which implements SEED algorithm is described. To satisfy trade-off between area and speed, the coprocessor has structure in which 1 round operation is divided into three subrounds and then subround is executed for one clock. To improve clock frequency online precomputation scheme for round key is used. To apply the coprocessor to various applications, four operating modes such as ECB, CBC, CFB, and OFB are supported. Also to eliminate performance degradation due to data input and data output time between host computer and coprocesor, background input/output method is used. The cryptographic coprocessor is designed using 0.25㎛ CMOS technology and consists of about 29,300 gates. Its peak performance is about 237 Mbps encryption or decryption rate under 100 Mhz clock frequncy and ECB mode.
A Comparative Analysis of Service Charge and Discount Scheme of ISDN Operators
김문수 ; 지경용 ; 강국창 ; 허홍석 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1618~1618
ISDN, the beginning of broadband and multimedia service, is a digital network that provides integrated end-to-end digital telecommunication services for transmissions of different kinds of information, from voice and facsimiles to data and images. In Japan, Britain and U. S there has been shown the demand of ISDN is considerable and ISDN technology is becoming quite stable. Furthermore,their ISDN service experience helps them to set up and carry out the marketing strategies for Internet access services such as ADSL, Cable Modem and WLL, etc. This paper examines and compares services, charge and discount scheme of ISDN across 14 telecommunication carriers. It can be utilize as a reference for diffusing ISDN as well as developing Internet access services and marketing strategies.
A Semi-MMIC Hair-pin Resonator Oscillator for K-Band Application
이현태 ; 이종철 ; 김종헌 ; 김남영 ; 김복기 ; 홍의석 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 9, 2000, Pages 1635~1635
In this paper, a 18 GHz oscillator is designed with the push-push method an fabricated by semi-MMIC process, in which the second harmonic is the main output signal with the suppressed fundamental mode. In semi-MMIC process, passive components with microstrip transmission line are implemented using MMIC process on semi-insulating GaAs substrate. Then, chip types of P-HEMT, resistors, and capacitors are connected through Au wire-bonding. Also, the ground plane is inserted around the circuit and connected each other with the back-side of substrate through Au wire-bonding instead of via-hole. The semi-MMIC push-push oscillator shows the output powder of -10.5 dBm, the fundamental frequency suppression of -17.3 dBc/Hz, and the phase noise of -97.9 dBc/Hz at the offset frequency of 100 kHz.