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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
Volume 25, Issue 12 - 00 2000
Volume 25, Issue 10 - 00 2000
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A Study On Performance fo Fiber Optic CDMA System for Parallel Transmission of Two Dimensional Data
이태훈 ; 박영재 ; 박진배 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 1~1
Generally, one-dimensional fiber optie code-division multiple-acess(CDMA) system is encoded and decoded using optical orthogonal codes(OOC's), whereas two-dimensional fiber optic CDMA system uses optical orthogonal signature pattern codes(OOSPC's) for parallel data link process. The OOSPC's should have good autocorrelation and corss-correlation properties. However, if timing information or synchronization of OOSPC's can be obtained by other means, the property of autocorrelation may not be restricted and we can increase the number of pattern codes. In this paper we introduce the fiber optic CDMA system for parallel transmission of two-dimensional data and investigate methods of generation of two-dimensional pattern codes. The probability density function of interference noise is calculated in interfering OOSPC's of other users and the corresponding bit error rate is derived. We compare each OOSPC's by plotting bit error rate versus threshold values and the number of simulataneous users, from the result, we propose the optimal OOSPC's conditions for the parallel transmission of two-dimensional data.
Analysis and assessment of the gain of optically pumped surface-normal optical amplifiers
김운하 ; 정기태 ; 조용환 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 8~8
This paper analyzes and accesses the gain of optically pumped surface-normal MQW optical amplifiers. The proposed amplifiers have the advantage of polarization independence, high coupling efficiency to and from optical fibers, and flexibility of operating wavelength. We analyzed the gain characteristics of 100 - 200-period MQWs and verified the dependence of a strained lattice and selective doping. Theoretical analysis of such MQWs shows a single-pass gain of 3 dB with broad operation bandwidth. A single-pass gain of 2.6 dB is obtained experimentally in a InGaAs/InGaAlAs MQW amplifier, which is compared with calculations. The use of Fabry-Perot interferometer (FRI) structure in an optical amplifier is a useful way to increase the gain above 2 to 3 dB is a prerequisite to achieve both a high gain and moderate operation bandwidth in FBI-structured optical amplifiers. We have designed an FPI-structured surface-normal optical amplifier both with a high gain of broad operation bandwidth of 4.6mm, when a single-pass gain is 3 dB.
An Optimization Model and Heuristic Algorithms for Multi-Ring Design in Fiber-Optic Networks
이인행 ; 이영옥 ; 정순기 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 15~15
The important considerations in the design of fiber-optic networks are reliability and survivability preparing against a failure. The SDH(Synchronous Digital Hierarchy), the international standard of optical transmission, offers several network reconfiguration methods that enable network to be automatically restored from failure. One of the methods is the SHR(Self Healing Ring), which is a ring topology system. Most network providers have constructed their backbone networks with SHR architecture since it can provide survivability economically. The network architecture has eventually evolved into a multi-ring network comprised of interconnected rings. This paper addresses multi-ring network design problems. It is assumed that each ring is a Bi-directional SHR(BSHR) with demand splitting. One of the design problems is to minimize ring-construction cost. This problem can be formulated with MIP(mixed integer programming) model. However, it is difficult to solve the model within reasonable computing time on a large scale network because the model is NP-complete. Furthermore, in practice we should consider the problem of routing demands on rings to minimize total cost. This routing problem involves multiplex bundling at the intermediate nodes. A family of heuristic algorithms is presented for this problem. These algorithms include gateway selection and routing of inter-ring demands as well as land balancing on single rings. The developed heuristic algorithms are applied to some network provider's regional and long-distance transmission networks. We show an example of ring design process and compare it with another ring topology desing. Finally, we analysis the effect of bundling.
Design of a new family of multi wavelength two-dimensional codes for optical code division multiple access networks
유경식 ; 박남규 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 31~31
It has been known that the optical code division multiple access (OCDMA) is a prominent future technology to support many simultaneous users and to increase transmission capacit of optical fiber. In this paper, we proposed the new construction of 2 dimensional code, which can be used as a codeword in temporal/wavelength OCDMA networks. New code family is obtained by extending the concept of Hamming correlation. All optical encoder and decoder for newly proposed code were also developed. In considering bit error ratio, we verified that new coding scheme outperforms conventional coding scheme by simulation. This system is applicable to asynchronous fast local area network, which needs a high security level and a flexible network configuration.
Off-level sampling Method for Bias stabilization of an Electro-Optic Mach-Zehnder Modulator
양충열 ; 홍현하 ; 김해근 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 42~42
A new method for stabilizing the bias of an Electro-Optic Mach-Zehnder modulator has been developed to maximize the switching extinction ratio in burst mode packet traffic. By sampling and minimizing the off-level output power of the modulator, a high extinction optical gate switch in obtain regardless of the variation of the packet traffic density.
Design and performance of asymmetric TEM cell for calibrating field probes
윤재훈 ; 이혁재 ; 황호정 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 48~48
The design techniques of an asymmetric TEM (ATEM) cell for calibrating E/H field probes are presented in this paper. The authors describe the techniques to obtain not only the arbitrary frequency window between first resonant frequency and second resonant frequency, but also the test space with ±2dB field uniformity. We could design an ATEM cell that the measured data, electric field distribution inside the cell, impedance matching and resonant frequencies, agree with the calculated results.
Limit of Node Expandability Considering ASE Noise and Protection Architecture in WDM SHR
박영일 ; 채창준 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 56~56
The maximum number of nodes in WDM self healing ring network is limited by several factors including network architecture and ASE noise due to EDFAs at each optical ADM node. In this paper, the maximum node numbers for several protection architectures and bit rates limited by ASE are calculated and compared with the number limited by wavelength numbers. Appropriate design rules can be deduced from these results.
Suppression of mutual interference among vehicular radars by ON-OFF control of pulses
최병철 ; 김용철 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 62~62
Intelligent vehicles are equipped with radar sensors for collision avoidance. We present a method of suppressing mutual interference among pulse-type radars, where all the radars are standardized. We developed a method of separating the true self-reflection from the false one by controlling the pulse emission of a radar in an orthogonal On, OFF pattern. Interference signal identified in OFF-intervals recorded to indicate the positions of the expected ghosts in ON-intervals. PFA and PM are derived for a radar system with I-Q demodulation scheme, where Gaussian noise alone is Rayleigh-distributed and Gaussian noise plus reflected radar pulse are Rician-distributed. The value of the threshold adaptively updated in order to prevent the deterioration of Pm. In the experimental result, PFA decreases by an order of 10,000, when compared with the conventional M of N majority voting method.
Design of a Three Dimensional Audio System for Multicast Conferencing
김영오 ; 고대식 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 71~71
On multimedia teleconferencing system existing a number of participants, face of the participants can be perceived by visual image. However, differentiation of each participant's voice and spaciousness sense are very hard since voice of all participants is processed with one dimensional data. In this paper, we implemented three dimensional audio rendering system using the HRTF(Head Related Transfer Function) and distance sense reproduction method and determined the optimal location of the participants for teleconferencing system. In the results of the listening test using elevation and azimuth angle, we showed that directional perception of the azimuth angles were better than that of the elevation ang les. Specially, we showed that participant location using the HRTFs of the azimuth angle 10°, 90°, 270° and 350° was efficient in teleconferencing system existing four participants. We also proposed that distance cue was used for enhancement of the reality and location of many participants more than five.
Efficient Rate Control by Lagrange Multiplier Using Adaptive Mode Selection in Video Coding
류철 ; 김승필 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 77~77
This paper presents an approach for rate control by adaptively selecting macroblock modes in video coding.The problem of rate control has been investigated by many authors where quantizer level is adjusted based on the buffer fullness.The proposed approach is different from the previous ones  in that it finds the optimal decision curve rather than finding a set of the modes. Proposed algorithm extends the coding decision options for rate control to motion/no-motion compensation as well as inter/intra decisions. Instead of having a fixed motion/no-motion compensation or inter/intra decision curve, one can utilize an adaptive decision curve based on the characteristics of input frames so that the PSNR at a given bit rate is maximized. Therefore, the proposed approach provides better rate control than simple quantizer feedback approach in terms of visual quality. The curve is obtained by utilizing simulated annealing optimization technique. The algorithm is implemented and simulations are compared with other approaches within H.261 video codec.
An Adaptive Active Noise Cancelling Model Using Wavelet Transform and M-channel Subband QMF Filter Banks
허영대 ; 권기룡 ; 문광석 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 89~89
This paper presents an active noise cancelling model using wavelet transform and subband filter panks based on adaptive filter. The analysis filter banks decompose input and error signals into QMF filtered of Towpass and highpass bands. Each filter bank uses wavelet filter with dyadic tree structure. The dooomposed input and error signals are iterated by adaptive filter coefficients of each subband using filtered-X LMS algorithm. The synthesis filter banks make output signal of wideband with perfect reconstruction to prepare adaptive filter output signals of each subband. The analysis and synthesis filter banks use conjugate quadrature filters for perfect reconstruction. Also, The delayed LMS algorithm model for on-line identification of error path transfer characteristics is used gain and acoustic time delay factors. The proposed adaptive active noise cancelling model is suggested by system retaining the computational and convergence speed advantage using wavelet subband filter banks.
Wavelet-based Digital Watermarking with Chaotic Sequences
김유신 ; 김민철 ; 원치선 ; 이재진 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 99~99
In this paper, as a digital watermark, we propose to use a chaotic sequence instead of the conventional Gaussian sequence. It is relatively easy to generate the chaotic sequence and is very sensitive to the change of initial value. The chaotic sequence adopted in this paper is a modified version of logistic map to give the sequence distribution of Chebyshev map. In the experiments, we applied the Gaussian sequence and chaotic sequence to wavelet coefficients of image to compare the similarity distribution. The results show that, as in the DCT-based watermarking system, the chaotic sequence is robust for various signal processing attacks. Moreover, the similarity variance is smaller than the Gaussian sequence for iterative experiments. It also shows a better performance for compression errors than the Gaussian sequence.
Design method for optical transversal filter with an optical amplifier
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 105~105
To realize a desired characteristics of an optical transversal filters, The number of optical amplifiers as same as the lentgh of a given transfer function is needed. In this paper, we consider an optical transversal filter that uses only one fiber amplifier, which can realize a constant(=α) times of a given transfer function with α as large as possible in order to make use of optical signal energy. We also present some applications using this optical fiber filter.
IR Signal Analysis and Band Selection for Two-color Seeker
오정수 ; 서동선 ; 최종수 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 112~112
A two-color infrared (IR) seeker employs two detection-bands for efficient target tracking under countermeasures and background noises. This paper describes a study on the detection-band selections for the two-color seeker. To select the detection-bands, we analysis infrared radiation characteristics of a target, a flare, and background noises and then other characteristics closely related with the received power, such as the atmospheric transmission, acquisition range, background noise effect, and signal-to-noises. The analysis shows that the pertinent bands of two-color IR seeker are 3㎛~5㎛ for target detection and 1.5㎛~1.7㎛ for counter countermeasures. The results of our study will play a significant role in the further study of two-color seekers.
Mutispectral Image Compression Using Classified Interband Prediction and Vector Quantization in Wavelet domain
반성원 ; 권성근 ; 이종원 ; 박경남 ; 김영춘 ; 장종국 ; 이건일 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 120~120
In this paper, we propose multispectral image compression using classified interband prediction and vector quantization in wavelet domain. This method classifies each region considering reflection characteristics of each band in image data. In wavelet domain, we perform the classified intraband VQ to remove intraband redundancy for a reference band image that has the lowest spatial variance and the best correlation with other band. And in wavelet domain, we perform the classified interband prediction to remove interband redundancy for the remaining bands. Then error wavelet coefficients between original image and predicted image are intraband vector quantized to reduce prediction error. Experiments on remotely sensed satellite image show that coding efficiency of the proposed method is better than that of the conventional method.
A Fast Block Matching Algorithm Using Mean Absolute Error of Neighbor Search Point and Search Region Reduction
정원식 ; 이법기 ; 한찬호 ; 권성근 ; 장종국 ; 이건일 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 128~128
In this paper, we propose a fast block matching algorithm using the mean absolute error (MAE) of neighbor search point and search region reduction. The proposed algorithm is composed of two stages. At the first stage, the search region is divided into nonoverlapped 3×3 areas and MAE of the center point of each area is calculated. The minimum MAE value of all the calculated MAE's is determined as reference MAE. At the second stage, because the possibility that final motion vector exist near the position of reference MAE is very high, we use smaller search region than first stage. And, using the MAE of center point of each area, the lower bound of rest search point of each area is calculated and block matching process is performed only at the search points that the lower bound is smaller than reference MAE. By doing so, we can significantly reduce the computational complexity while keep the increasement of motion estimation error small.
The Image Restoration using Dual Adaptive Regularization Operators
김승묵 ; 전우상 ; 이태흥 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 141~141
In the restoration of degraded noisy motion blurred image, we have trade-off problem between smoothing the noise and restoration of the edge region. While the noise is smoothed, the edge or details will be corrupted. On the other hand, restoring the edge will amplify the noise. To solve this problem we propose an adaptive algorithm which uses I-H regularization operator for flat region and Laplacian regularization operator for edge region. Through the experiments, we verify that the proposed method shows better results in the suppression of the noise amplification in flat region, introducing less ringing artifacts in edge region and better ISNR than those of the conventional ones.
Progressive Region of Interest Coding Using the Embedded Coding Technique
최호중 ; 강의성 ; 다나카 도시히사 ; 고성제 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 148~148
In image coding applications such as web browsing and image database searching, it is very useful to quickly view a small portion of the image with higher quality. Region of interest (ROI) coding technique provides the capability to reconstruct the ROI in advance of decompressing the rest of the image, with a smaller number of transmitted bits compared to the case where the entire image is treated with the same priority. In this paper, a progressive ROI coding method using the embedded coder is presented, and an efficient transmission method for the ROI information. Experimental results show that the proposed progressive ROI coding technique can be effectively used for image coding applications such as web browsing and image database searching system.
Rate-Distortion Based Image Segmentation Using Recursive Merging and Texture Approximation
정춘식 ; 임채환 ; 김남철 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 156~156
A rate-distortion based segmentation using recursive merging is presented, which considers texture as a homogeneity by adopting the procedure of a generalized texture approximation. The texture in a region is approximated by SA-DCT and a set of two uniform quantizers with fixed step sizes, one for DC and another for AC. Using the approximated texture, we calculated the rate-distortion based cost. The segmentation using recursive merging is performed by using the rate-distortion based cost. Experimental results for 256×256 Lena show that the region-based coding using the proposed segmentation yields the PSNR improvements of 0.8~1.0 dB and 1.2~1.5 dB over that using the rate-distortion based segmentation with DC approximation only and JPEG, respectively.
Fast Block Motion Estimation Using the Characteristics of the Motion in Search Region
최정현 ; 박대규 ; 정태연 ; 이경환 ; 이법기 ; 김덕규 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 167~167
The three-step search(TSS) algorithm, a simple and gradual motion estimation algorithm, has been widely used in some low bit-rate video compression. We propose a new fast block motion estimation algorithm using the characteristics of motion in search region. Most of motion vectors exist in the center region of search area, so the motion in that region is examind more closely than TSS in this paper. Also in a search step, motion vector is estimated in the local area which is not overlapped with the search area in previous step, considering the all possible direction of motion. Therefore, we get the better motion estimation and reduce computational time in compared with the conventional methods.
Fabrication of an IrDA transceiver module for wireless infrared communication system OPR1002
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 175~175
A hybrid-type wireless infrared data communication module was fabricated by using the light emitting and absorption diodes with the one-chip of integrated digital circuits. The light emitting diode with the peak spectrum of 850nm was made from compound semiconductor material of AlGaAs and shows high speed signal transmission with the delay time of 60nsec for the light direction angle of 30°. The Si PIN photodiode shows the good absorption rate for the range of wavelenght of 450~1050 nm and convex-type epoxy lens was utilized for the spectrum filtering on the visible-range spectru below 750 nm. The data transmission speed is 115.2 kbps and the fabricated module satisfies on the IrDA 1.0 SIR standard requirements.
Design of a CMOS PLL with a Current Pumping Algorithm for Clock Syncronization
성혁준 ; 윤광섭 ; 강진구 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 183~183
In this paper, the dual looped CMOS PLL with 3-250MHz input locking range at a single +3.3V is designed. This paper proposed a new PLL architecture with a current pumping algorithm to improve voltage-to-frequency linearity of VCO(Voltage Controlled Oscillator). The designed VCO operates at a wide frequency range of 75.8MHz-1GHz with a high linearity. Also, PFD(Phase Frequency Detector) circuit preventing voltage fluctuation of the charge pump with loop filter circuit under the locked condition is designed. The simulation results of the PLL using 0.6μm N-well single poly triple metal CMOS technology illustrate a locking time of 3.5μs, a power dissipation of 93mW at 1GHz operating frequency with 125MHz of input frequency, Measured results show that the phase noise of VCO with V-Ⅰ converter is -100.3dBc/Hz at a 100kHz offset frequency.
A Study on Memory Control Algorithm of a Compact Color QUAD System
손종형 ; 정정화 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 193~193
10Gbps Time-Division Multiplexer using SiGe HBT
이상흥 ; 강진영 ; 송민규 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 1, 2000, Pages 201~201
In the transmitter of optical communication systems, a time-division multiplexer combines several parallel data streams into a single data stream with a high bit rate. In this paper, we design a 4:1 (4-channels) time-division multiplexer using SiGe HBT with emitter size of 2x8um². The operation speed is 10Gbps, the rise and fall times of 20-80% are 34ps and 34ps, respectively and the dissipation of power is 1.50W.