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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 19, Issue 12 - Dec 1994
Volume 19, Issue 11 - Nov 1994
Volume 19, Issue 10 - Oct 1994
Volume 19, Issue 9 - Sep 1994
Volume 19, Issue 8 - Aug 1994
Volume 19, Issue 7 - Jul 1994
Volume 19, Issue 6 - Jun 1994
Volume 19, Issue 5 - May 1994
Volume 19, Issue 4 - Apr 1994
Volume 19, Issue 3 - Mar 1994
Volume 19, Issue 2 - Feb 1994
Volume 19, Issue 1 - Jan 1994
Selecting the target year
A Study on the Traffic Generator to Evaluate ATM Switch
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 391~400
Recently, the development of ATM switch, a backbone system of BISDN, is receiving worldwide study. Because the development of large communication equipments like a switching system need a lot of time and cost, the performance evaluation by menas of simulation is needed for the higher efficiency of development before actual implementation. So, a general and objective input environment is necessary for proper simulation. The main purpose of this paper is to offer a traffic generator which can provide such input environment as a file for computer simulation of ATM switch. To offer diverse input environment of ATM switch, we select parameters, and implement ATM traffic generator with software technology. Basides, a program to verify the propriety of ATM traffic generator in also proposed. It is expected that the proposed ATM traffic generator will offer diverse input environment for computer simulation to evaluate new ATM switching system, not influenced by any system structure.
On Designing Domino CMOS Circuits for High Testability
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 401~417
In this paper, a new testable design technique for domino CMOS circuits is proposed to detect stuck-at(s-at), stuck-open(s-op) and stuck-on(s-on) faults in the circuits by observing logic test reponses. The proposed technique adds one pMOS transistor per domino CMOS gate for s-op and s-on faults testing of nMOS transistors and one nMOS transistors and one nMOS transistor per domino gate or multilevel circuit to detect s-on faults in pMOS transistors of inverters in the circuit. The extra transistors enable the proposed testable circuit to operate like a pseudo static nMOS circuit while testing nMOS transistors in domino CMOS circuits. Therefore, the two=phase operation of a precharge phase and a evaluation phase is not needed to keep the domino CMOS circuit from malfunctionong due to circuit delays in the test mode, which reduces the testing time and the complexity of test generation. Most faults of th transistors in the proposed testable domino CMOS circuit can be detected by single test patterns. The use of single test patterns makes the testing of the proposed testable domino CMOS circuit free from path delays, timing skews, chage sharing and glitches. In the proposed design, the testing of the faults which, require test sequences also becomes free from test invalidation. The conventional automatic test pattern generators(ATPG) can be used for generating test patterns to detect faults in the circuits.
Algebraic Geometric Codes and Subfields of Hermitian Function Field
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 418~424
Like the Hermitian function field over GF(q), those subfields defined by y +y=x where s divides q+1 are also maximal, having the maximum number os places of degree one permissible by the Hasse-Weil bound. Geometric Goppa codes(or algebraic geometric codes) arising from these subfields of the Hermitian function field are studied in this paper. Their dimension and minimum distance are explicilty and completely presented for any m with m
A Study on Design Method of Tap-off with High Performance for CATV Transmitting Circuits
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 425~433
The conventional weakly-coupled tap-off for CATV and/or MATV transmitting circuits has been fabricated empirically and experimentally. So, the theoretical analysis or the design method of the conventional one has not been established, the characteristics of which were not good. To solve these problems, we have proposed a modified weakly-coupled freedom in design. This paper describes the design theories and analysis method of the theoretical frequency characteristics of a Modified Weakly-coupled Tap-off with high density of coupling intervals for CATV and/or MATV system. From the theoretical analysis it has been shown that the frequency characteristics of the tap-off proposed here are improved much in comparision with the conventional one. Furthermore, the practical measurements of frequency characteristics for the fabricated circuits show agreement with the theoretical results, and hence, the validity of proposed design and analysis methods has been confirmed.
Analysis of the Traffic Characteristics for MAP Network Management System
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 434~441
In this paper, performance of MAP management system traffic is analyzed, to realize the network management function in automated manufacturing network mini-MAP. The network management system, which controls and supervises the network resources in the communication network, is the function that is necessarily required in this network. Since the real time response must be required in the Mini-MAP network, the delay performance of the network needs to be analyzed. By means of both analytical method and simulation for cyclic queueing model, the delay time distributions due to the increasement of transmission data are obtained in the implemented management network where SLAM II package is used for simulation. In addition, the parameters of the management function affecting the transmission delay are considered so that these parameters can be used to implement network management system.
Tracking of SFH/MFSK Signal in HF Channel
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 442~450
In this paper, the tracking of SFH/MFSK signals by using a paeallel correlator and a bank of BPF which is implemented by DFT recursively is studied. During symbol period, M-ary signal`s spectrum is analyzed by the step of n multiple of sampling period. The bank of BPF output which is stored for hop duration input to the parallel correlator. The time difference of the receiver and the transmitter is corrected by using sampling position and correlation time at which the largest output of correlator is generated. Syncronization signal detection rate and distribution of the largest output of correlator are evaluated by computer simulation in HF channel evironments for the performance analysis of proposed tracking method.
Public Data Network Services with an ISDN for a Developing Country
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 451~461
For developing countries which are in infant state of data communication services or don`t have their own Packet Switched Public Data Network(PSPDN), we present the strategy to construct the public data communication network, which guarantees the easy diffusion of data communication services, agrees with trends of telecommunication technology, and maximizes the outcomes to investments. With analyzing the characteristics of telecommunication infrastructures and demands of data communication services in a developing country, we show that the introduction of ISDN is the best solution for constructing a public data network. We also suggest aggressive approach to realize the packet switching functions into ISDN switching system and the networking scenario consisting of three graceful steps, based on the evolution of network architectures. Finally we show that the TDX-10 ISDN switching system, which is designed especially for developing countries, is helpful to commence the data communication era.
The Design and Implementation of an Enhanced Hypermedia System integrated with Object-Oriented Database Technology
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 462~478
Conventional hypermedia systems provide a simple data model based on nodes and link, and give us the limited capability in information retrieval such as browsing and navigating following the links. In this paper, we design and implement a hypermedia system (AHEAD) with enhanced data modeling and querying capability, which are strongly supported in object-oriented database technology. The AHEAD makes it possible to model the accurate data semantics and relationships in application domain, to represent useful information related to nodes and links, and to define the structure and manipulation operations of multimedia data. It also support the various querying capabilities by using modeling information.
Cell Priority Control with 2-Level Thresholds in ATM Switch Network
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 479~491
In this paper, we proposed cell priority control with 2-level thresholds, which was considered cell loss and cell delay requirement, in ATM switch with output buffer. Priority control mechanism presented in this paper improved cell loss rate for cell loss censitive cell and cell delay for delay censitive cell. In this mechanism cell loss rate and mean cell delay of cell priority control mechanism were obtained theoretically. The results show that cell loss rate and mean cell delay improvement become better by adjusting two thresholds according to QOS characteristics.
A Study of Traffics and Priority Assignments with Markov Process in ATM Networks
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 492~504
In ATM network was two QOS bearer services for flexible bandwidth assignment, various priority assignment buffer access mechanisms have been sugested. In this paper, a performance model with 3 state discrete time Markov proess in explicit priority assignment is suggested and cell loss probability is analytically derived. Also flexible space priority control mechanism with partial buffer sharing is studied and verified by simulation with OPNET.
KOREASAT On-Orbit Normal Mode Attitude Control System
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 505~514
Koreasat spacecraft requires accurate and reliable attitude control to provide beam pointing for tenyear long communication and direction broadcasting services. This paper describes the detailed design and performance of an on-orbit normal mode attitude control subsystem for the spacecraft. Koreasat used a momentum wheel which has nominal momentum 475in-1b sec(547.6cm-kg sec) aligned with the pitch axis to control pitch attitude and provide gyroscopic stiffness in roll/yaw plane and used a 300 atm magnetic torquer to control the roll and yaw attitudes. An Earth Sensor Assembly (ESA) is used to provide pitch and roll information for the on-board micropocessor. The roll/yaw control used bang-off-bang control and while pitch axis control used proportional and integral control law. Control system errors during the operational normal mode are 0.03 deg, 0.1 deg and 0.01 deg in roll, yaw and pitch axes, respectively. Current attitude control system provides adequate control performances to capture initial attitude errors and spacecraft nutation.
A Study on the Radiation Characteristics of the Conical Corrugated Feed Horn using the Gaussian Beam Mode
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 515~522
The radiation characteristics of the conical corrugated feed horn are analyzed by the Gaussian beam mode theory. the electric field over the aperture can be expanded in terms of a set of Gaussian-Laguerre modes. It is proved that these modes are the solutions of the wave epuations for the paraxial approximation. A method, using the sum of the mode expansion coefficients instead of calculation only the fundamental mode, is presented in order to reduce the radiation pattern error. For illustrative examples, the radiation patterns of the corrugated horn antenna operting over C, Ku, and mm-wave band are calculated. Our results agree well with the results obtained by the vector potential method over each band, and also agree well with the measured value at 6.175GHz.
The Characteristic Impedance and the Electric Field Uniformity of a GTEM Cell
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 523~532
A knowledge of the accurate characteristic impedance of a GTEM cell is very useful to design it. This paper discusses the characteristic impedance of a GTEM cell applicable to both susceptibility and emission measurements, considering opening angle of it. The over-RGM for analysis is described : this numerical method is operated with respect to the spherical coordinate system. Some results are compared with others and the validity of this analysis is estabished. The characteristic impedances of a GTEM cell with the variation of geometrical constructions on cross section are presented ; the effect of the opening angle on the characteristic impedance is show. Finally, the electirc field uniformities on a cross section of a GTEM cell are considered for various opening angles.
A Study on the Detection of Hazardous Weather Conditions by a Doppler Weather Radar
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 533~542
In a Doppler weather radar, high resolution windspeed profile measurements are needed to provide reliable detection of a hazardous weather condition. For this purpose, the pulse-pair method is generally considered to be the most efficient estimator. However, this estimator has some bias errors due to asymmetric spectra and may yield meaningless results in the case of a multimodal return spectrum in this paper, bias errors were analyzed and an improved method was suggested to reduece these errors. For the case of a multimodal or seriously skewed spectrum, the modes of spectrum may provide more reliable information than the statistical mean. Therefore, the idea of a relatively simple mode estimator is also developed.
Design of Dynamic Time Warp Element for Speech Recognition
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 543~552
Dynamic Time Warp(DTW) needs for iterative calculations and the design of PE cell suitable for the operations is very important. Accordingly, this paper aims at real time recognition design enables large dictionary hardware realization using DTW algorithm. The DTW PE cell separated into three large blocks. "MIN" is the one block for counting accumulated minimum distance. "ADD" block calculates these minimum distances, and "ABS" seeks for the absolute values to the total sum of local distances. Circuit design and verification about the three block have been accomplished, and performed layout '||'&'||' DRC(design rule check) using 1.2 m CMOS N-Well rule base.CMOS N-Well rule base.
Analysis of a Coupled Microstrip-Slot Line in the Spectral Domain
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 553~559
A coupled microstrip-slot line is analyzed using a full wave method in the specral domain. The characteristics of the coupled microstrip-slot line are obtained based on the Galerkin`s method. The characteristics of even mode by microstrip line and odd mode by slot line are calculated respectively. Especially the singularity of basis function is enforced to be considered with respect of modes. Numerical results are compared with available data and shown good agreement.
A Design of RAKE Receiver for Cellular CDMA Communications
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 560~572
This paper describes a design of RAKE receiver for the cellular CDMA mobile communication system on the multipath fading channel. To measure impulse response on the multipath fading environment. partial correlation properties of short PN code that transmitted at a cell site through the pilot channel was used. We used 12 despread paths for compensating about 10 s multipath spread and proposed the compensation algorithm. For processing of digital converted input signal, we proposed full digitalized logics and its validity was verified by computer and timing simulation.
A Design of Dual-Polarized Microstrip Antenna Using the Active Devices
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 573~581
A microstrip antenna having a dual polarization and a smaller size than feed horn polarizer of F.R.R.S(Faraday Rotation Rotary Switch) is designed, in which GaAs MESFET switches are inserted for selective reception of RHCP or LHCP. For an accurate analysis of the resonance frequency, input impedance and radiation pattern of the circularly polarized microstrip antenna, finite difference time domain (FDTD) method is used. When the GaAs MESFET switch in the feeder is ON-stats, the truncated patch antenna has a gain of about 16.6dB including amplifier gain, while the switch is OFF-state, this has a isolation level of -24dB.
Performance of 2-Carrier DS system and its MODEM designed for Power Line Transmission
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 582~590
This paper introduce a highly verstile and simple data transmission system designed for commercial power distribution lines. The system operates on the DSSS principle but utilizes two independent carrier frequencies each represents polarity of DS MODEM outiputs. At the receiving terminal, outputs of two envelope detectors are directly applied to separate DS correlators before the two components are compared. The recovered signals which represents data and line noise are then compared at comparator. With the noise power greatly rudused at the correlator, the error rate of the data observed at comparator desplays great improvement comparing to the conventional FSK-DS system in which the detector output are compared before the correlator stage. Despite its simplest structure, the prototype MODEM transmitts 2400 bps with the error rate 10 , about 10dB improved compared to conventional FSK system.
Effect of Stripe Width on Threshold in Single Quantum Well Laser Diodes
The Journal of Korean Institute of Communications and Information Sciences, volume 19, issue 3, 1994, Pages 591~596
Threshold dependence on stripe width in gain-guided single quantum well lasers has been examined by complex domain effective index method. It is found, in narrow stripe regime, that the lateral optical confinement estimated by newly introduced parameters decreases very rapidly as the transverse optical confinement factor decreases. Thus, in a single quantum well laser with a usually very small, the optical confinement may become very poor depending on stripe width not only in the transverse but also in the lateral direction, further enhancing the gain saturation and often leading to an anomalously high threshold current. The understanding of rather anomalous threshold dependence on stripe width will be very important in optimization of quantum well laser diode structure.