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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 16, Issue 12 - Dec 1991
Volume 16, Issue 11 - Nov 1991
Volume 16, Issue 10 - Oct 1991
Volume 16, Issue 9 - Sep 1991
Volume 16, Issue 8 - Aug 1991
Volume 16, Issue 7 - Jul 1991
Volume 16, Issue 6 - Jun 1991
Volume 16, Issue 5 - May 1991
Volume 16, Issue 4 - Apr 1991
Volume 16, Issue 3 - Mar 1991
Volume 16, Issue 2 - Feb 1991
Volume 16, Issue 1 - Jan 1991
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Blue-Green Laesrs and Their Application to Undrewater Communication
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1211~1218
The under water communication which use blue green lasers reviewed. In the view point of absorption and scattering, the optical characteristics of sea water are described. In addition, state of blue green lasers for under water communication are summarized
A Design of ANC-ALE Model Using the JP Lattie Filter
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1219~1228
In the actual case, a model of noise canceller using adaptive filter has both a channel transfer function from noise source to main signal input and to noise canceller input. The previous models of noise canceller have been considered to be only one side channel transfer function. Therefore, it is proposed that a new model has two channel transfer functions and derives an optimal tranfer function of adaptive noise canceller. The adaptive filter is using the joint process lattice filter that has fast adaptive speed. The signal noise radio has been improved by a model of ANC-ALE and it is confirmed with computer simulation. Beside, a dc bias is very effective for noise cancelling, especially to the particular signal.
A Study on th Improvement of Image Detection in th Solid-subsurface Using th Acoustic Shear Wave
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1229~1235
On Factorizing the Discrete Cosine Transform Matrix
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1236~1248
A new fast algorithm for computing the discrete cosine transform(DCT) Is developed decomposing N-point DCT into an N /2-point DCT and two N /4 point transforms(transpose of an N /4-point DCT. TN/t'and)It has an important characteristic that in this method, the roundoff noise power for a fixed point arithmetic can be reduced significantly with respect to the wellknown fast algorithms of Lee and Chen. since most coefficients for multiplication are distributed at the nodes close to the output and far from the input in the signal flow graph In addition, it also shows three other versions of factorization of DCT matrix with the same number of operations but with the different distributions of multiplication coefficients.
A Fast and Adaptive Feature Extraction Method for Textured Image Segmentation
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1249~1265
In this paper, a fast and adaptive feature extraction algorithm for textured image segmentation is proposed. First, a conventional algorithm to extract the statistical texture features are described and we obtain the recursive equations from that conventional method and it is used for extraction of sevaral texture features. And also we propose the adaptive algorithm which extract the texture features. To evaluate the performance of proposed algorithm, we apply the proposed method to artificial texture images. From the results of computer simulation, the proposed method is superior to the conventional one
Loss Measurements of Installed Single-Mode Optical Fibers
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1266~1273
Attenuation losses and repeater spans of single-mode optical fibers installed in the long hual optical transmission line were measured and analyzed. The average loss including splicing points was appeared to be 0.55 0.05dB/km and 0.59 0.01dB/km at 1300nm and 1550nm, respectively, and showed lager value at 1550nm window, The cause of loss increase at 1550nm range from the OTDR measurement was due to the inappropriate treatment of extra length of fiber at the splicing points. And average repeater span of domestic long haul line was 24 7km and 90% of total sampled repeater spans was within 31 km
Statistical Convergence Properties of an Adaptive Normalized LMS Algorithm with Gaussian Signals
Sung Ho CHO ; Iickho SONG ; Kwang Ho PARK ;
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1274~1285
This paper presents a statistical convergence analysis of the normalized least mean square(NLMS)algorithm that employs a single-pole lowpass filter, In this algorithm the lowpass filter is used to adjust its output towards the estimated value of the input signal power recursively. The estimated input signal power so obtained at each time is then used to normalize the convergence parameter. Under the assumption that the primary and reference inputs to the adaptive filter are zero mean wide sense stationary, and Gaussian random processes, and further making use of the independence assumption. we derive expressions that characterize the mean and maen squared behavior of the filter coefficients as well as the mean squared estimation error. Conditions for the mean and mean squared convergence are explored. Comparisons are also made between the performance of the NLMS algorithm and that of the popular least mean square(LMS) algorithm Finally, experimental results that show very good agreement between the analytical and emprincal results are presented.
Performance Analysis of Common Spreading Code CDMA Packet Radio Systems with Multiple Capture Capability
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1286~1299
In this paper we present a multiple capture model for common spreading code CDMA packet radio systems with star topology. Basic equations for the collision free, header detection. and multiple capture probabilities are derived at the central receiver. Link performances. including the average number of packet captures, allowable number of simultaneous transmission, and system throughput are theoretically evaluated for a hybrid system. combining envelope header detection and differential data detection, Using the Block Oriented Systems Simulator(BOSS), simulations were carried out for the central receivers with envelope or differential geader detection, It is shown that for a threshold approx-imation to the probability of data packet success, the mulyiple capture model significantly improves system throughput.
A Study on the Blocking Probabilities of Single-buffered switching Networks with Time Slot Sequence Integrity of Multi-slot Calls
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1300~1312
In this paper we syudy the time slot sequence integrity(TSSI) of multi-slot calls in the single-buffered switching networks and analyze their traffic characteristics in terms of traffic mixture ratio, number of random searches for idle time slots, and their blocking probablities. This result can be utilized in the design of wideband switching networks in the single buffered systems, such as TDX IA/B swithcing systems, for accommodating multi slot calls.
A Study on the Implementation of CAM Generator Using Objected-Oriented Programming
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1313~1323
n this thesis CAM(content Addressable Memory) generator and graphic display tool for run-plot sequence in automatic generation of CAM are presented. We show that implementing the layout generation, graphic menu, mouse driver, and data structure by using the basic classes is clear and easy in modification than the conventional procedural language. For the implementation of generator which is independent of design rule or process, we use the parameterized cell so that basic cell can be changed according to user's inputs. and perform the layout by means of placement and routing using pitch mathching. Finally, the display of CIF which generated and constitution of graphic menu for total run-plot sequence are explained.
Phoneme Separation and Establishment of Time-Frequency Discriminative Pattern on Korean Syllables
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1324~1335
In this paper, a phoneme separation and an establishment of discriminative pattern of Korean phonemes are studied on experiment. The separation uses parameters such as pitch extraction, glottal peak pulse width of each pitch. speech duration. envelope and amplitude bias. The first pitch is extracted by deviations of glottal peak and width. energy and normalization on a bias on the top of vowel envelope. And then, it traces adjacent pitch to vowel in whole. On vewel, amethod to be reduced gliding pattern and the possible of vowel distinction to be used just second formant are proposed, and shrinking pitch waveform has nothing to do with pitch length is estimated. A pattern of envelope, spectrum, shrinking waveform, and a method of analysis by mutual relation among phonemes and manners of articulation on consonant are detected. As experimental results, 90% on vowel phoneme, 80% and 60% on initial and final consonant are discriminated.
A Study on the Implementation of PC Interface for Packet Terminal of ISDN
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1336~1347
In this paper, The PC interface for packet terminal of ISDN is designed and implemented in order to build packet communication networks which share computer resources and exchange informations between computer in the ISDN environment. The PC interface for packet terminal of ISDN constitutes S interface handler part which controls functions of ISDN layer1 and layer 2, constitutes packet handler part which controls services of X.25 protocol in the packet level.Where, The function of ISDN layer1 provides rules of electrical and mechanical characteristics, services for ISDN layer 2. The function of ISDN layer 2 provides function of LAPD procedure, services for X.25 The X.25 specifies interface between DCE and DTE for terminals operrating in the packet mode. The S interface handler part is orfanized by Am 79C30 ICs manufactured by Advanecd Micro Devices. ISDN packet handler part is organiged by AmZ8038 for FIFO for the purpose of D channel. The common signal procedure for D channel is controlled by Intel's 8086 microprocessor. The S interface handler part is based on ISDN layer1,2 is controlled by mail box in order to communicate between layers. The ISDN packet handler part is based on module in the X.25 lebel. The communication between S interface handler part and ISDN packet handler part is organized by interface controller.
The Design and Performance Analysis of Fiber Optic Metropolitan Area Network
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1348~1356
The need for MAN(Metropolitan Area Network)has been increased by demands for high performance comuter communication. According to the definition of MAN by IEEE 802.6 MANs have diameter of about 50km, bandwidth of more than 1Mbps, and limited delay, Because optical fibers have unique characteristics that make them attractive for the implementation of MANs several fiber optic networks suitable for MAN application have been proposed. Those networks have drawbacks such as unlimited delay, many processing nodes and limited number of stations. Also IEEE 802.6 proposals and oters improved networks were proposed, but they have complicated access procedures and data buffering and difficulties in implementation. This paper descrives the design of Fiber Optic Metropolitan Area Network in Seoul(Seoul FOMAN) to overcome the drawback, Seoul FOMAN is hierarchical MAN and designed based on the topology of 43 end offices in Seoul. We propose MAN topology, proper access protocol and analyze the performance
Methods of generating Hopping Patterns Based on Permutation Frequency Hopping SSMA System
Choon Sik YIM ; Ryuji KOHNO ; Hideki IMAI ;
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1357~1365
This paper proposes the generation of several classes of frequency hopping patterns. which are derived by permutation, for an asynchronous frequency hopping spread spectrum multiple accecss system (FH/SSMA). The first class of hopping patterns is obtained by using a Latin square. The second class of hopping patterns is derived by generalizing the first class which is designed by using a permutation technique. The third class of hopping patterns is designed by using a rotational base of elements. We evaluate the hit property of the proposed classes of hopping patterns when these patterns are nutually shifted in an FH/SSMA system. Compared to the Reed Slolmon sequences generated by the conventional method, the sequence obtained by the permutation technique can reduce the number of hits among hopping frequencies in asynchronous time/frequency shift.
Error Rate Performance of DS/QPSK Signal in m-distribution Fading Environment
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1366~1381
The error rate equation of QPSK signal received through m-distribution fading channel in tone interference and Gaussian noise environments has been derived and evaluated numerically to be shown in figures. The derivation has been done for two cases. The one case is that only the signal is under the influence of fading and the another case is that signal and interference are under the influence of fading simultaneously. The evaluated results show that the error that performance when fading influences signal and interference simultaneously is worse than that when fading influence signal only. Also the results show that a late amount of improvement can be gained by direct sequence spread spectrum system and the amount of improvement becomes small as the influence of interference and fading becomes small.
A Study on the Arithmetic Coding for Applications to Fax Machines
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1382~1397
The QM-Coder based on the recommandation of the JBIG committee has been studied for applying it to G3 FAX. In the point of view of implementation. the QM-Coder is modified to have following properties : 1) initialized at each start of the new line for protecting the error propagation, 2) pixel context for error estimation, fill bit insertion to meet minimum scan line time of 10 msec. and it is found that the modified QM-Coder is useful for encoding half tone images for low end G3 FAX machine, For higher compression ration than QM-Coder in encoding of the image binarized by ordered orther thchniques, a rearranging process before applying the QM-Coder is used and the resultant compression ratic was increased 1.13∼1.31 times than that of the conventional QM-Coder.
Error-Rate Performance of the
/4 shift QPSK Modulation Under Frequency Selective Fading Environment in Digital Mobile/Portable Radio Communications
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1398~1416
A Study on the Flow Control with Retransmission Algorithm
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1417~1422
In this paper we develop an analytic model for end-to-end communication protocols and study the window mechanism for flow control in store-and-forward computer networks. We develop a flow control model in which the parameters of the system are not dynamically adjusted to the stochastic fluctuation of the system load. Simulation results are presented and it is shown that the throughput-delay performance of a network can be improved by proper selection of the design parameter, such as timeout, the number of retransmission, etc.
A Study on the Extension of TTCN using Object-Oriented Model
The Journal of Korean Institute of Communications and Information Sciences, volume 16, issue 12, 1991, Pages 1423~1434
This paper extends TTCN, a conformance test notation, using object oriented concepts including object, class and inheritance. In distributed system environments, since test systems that should test the implementations for application protocols whether they conform to the standard protocol include protocol test behaviours executed in parallel, the converntional TTCN can't describe whole thest suites explicitly. ISO is working the extension of TTCN including parallel notations, but concurrently if TTCN could be applied by the object model that regards a parallel test component as a object, we would gain the advantages of reliability and software reusability, and make TTCN a test language.