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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of IKEEE
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Institude of Korean Electrical and Electronics Engineers
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Volume & Issues
Volume 4, Issue 2 - Dec 2000
Volume 4, Issue 1 - Jul 2000
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A study on the Mechanism of the Voltage Occurence in YBaCuO Superconductor
Lee, Sang-Heon ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 1~1
Magnetic characteristics observed in YBaCuO superconductor were studied. In the measurement of differential conductance, it was cleared that the mechanism of magnetic memory effect couldn't be explained by using conventional flux flow model. By changing the density of external magnetic flux, changes in inductance of a coil in which a superconducting bar inserted were also measured. The results showed that the filament model was valid to explain the mechanism of the occurrence of a voltage in superconducting sample. It was concluded that the electromagnetic characteristics arose from the interaction between the trapped magnetic flux and weak link of the filament formed in the superconducting bulk.
Performance Analysis of DS/CDMA Slotted ALOHA with Tree Algorithm
Ding, Zhe-Gen ; Park, Hyun-Suk ; Kwak, Kyung-Sup ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 12~12
Tree algorithm is a simple collision resolution technique that maintains stability without any complex estimation procedures and gains better throughput. In this paper, we propose a new system that CDMA ALOHA combines with tree algorithm for improving stability of system in reverse link channel. The stability of system is clarified with theoretical analysis when arrival rate
is smaller than
and the normalized theoretical stable throughput is obtained with dividing
by processing gain. Moreover, the performance of proposed system is investigated by comparing with the performance of system using retransmission algorithm.
Efficient Blocking Threshold Mechanism for CDMA Cellular Systems
Lee, Tae-Keun ; Park, Hyun-Suk ; Kwak, Kyung-Sup ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 19~19
In a CDMA cellular network, bursty user mobility causes negative effects on link availability, as well as on cellular network capacity. In the dynamic cell management, it is common to decrease the traffic of the target cell by reducing the cell coverage when the traffic of the target ceil increases. However, it is useless to use the dynamic cell management when the traffic of adjacent cells increases. In order to maximize the capacity of the cellular network, the blocking threshold has to he selected so that optimum balancing of the blocking probability, dropping probability, and link availability is achieved. In this paper, we used a mechanism which adjusts the cell coverage when its traffic increases. Furthermore, we propose a self-stabilize technique by adjusting a threshold of the cell blocking probability since it is not possible to decrease the traffic by hand-off if the inter-cell traffic increase. We show that the proposed method can decrease the dropping probability and increase the link availability.
A study on Cu Diffusion Properties of Cu/TiN/Si Films Treated by Rapid Thermal Annealing
Lee, Sang-Heon ; Kim, Young-Min ; Cho, Nam-In ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 27~27
Cu is an attractive material for interconnects in Si ULSI devices applications. TiN was deposited on (100) Si wafer using a reactive sputtering technique. Cu films were grown on TiN/Si substrates by Cu-CVD(chemical vapor deposition). In this study, Rapid Thermal Annealing(RTA) was carried out on Cu/TiN/Si films. The thermal stability indispensable for a barrier against Cu was on investigated using sheet resistance measurement. Surface roughness of the film was reformed from RTA carried out at
. Surface resistivity was found to be
. From these observations, it was confirmed that the TiN layer acted effectively as a brooking barrier for the diffusion of Cu atoms. It has been concluded that Cu atoms move through TiN layer and react with Si atoms from the substrate forming Cu-Siliside at the TiN/Si interface. The structure change of TiN layer accompanying with Cu diffusion has degraded the electric properties of the film.
Short-term load forecasting using the Kohonen neural network and wavelet transform
Yu, In-Keun ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 35~35
A novel composite model for short-time load forecasting of power systems using the Kohonen neural network and wavelet transform is proposed in this paper. The Kohonen neural network, which is used for the classifying of the daily loads by the SOFM, is adopted so that the forecasting accuracy is improved. Daubechies D2, D4 and D10 wavelet transforms are applied in order to decompose the weather(temperature) sensitive hourly loads that were classified into 4 patterns using the Kohonen neural network in advance. The wavelet coefficients associated with certain frequency and time localization are adjusted using the conventional multiple regression method and the components are reconstructed to predict the final loads through the five-scale synthesis technique. The outcome of the study clearly indicates that the proposed composite model of the Kohonen neural network and wavelet transform approach can be used as an attractive and effective means for short-term load forecasting.
A New Approach to Lane Detection on Highways
Jiang, Gang-Yi ; Choi, Tae-Young ; Hong, Suk-Kyo ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 44~44
In this paper, a new lane detection method, based on image processing and computer vision, is proposed for a driver assistant system. A new description on lane markings in the image plane is presented and used to detect lanes, and some properties are discussed. Efficient preprocessing techniques are proposed to increase the information of lane. Multi-frame lane detection and analysis are adopted so that the lane state detection is more reliable. The lane parameters are estimated and dynamically updated over time. The obtained parameters are used for lateral control. Experimental results show that the proposed method performs lane detection well.
New Approach to Impulse Noise Removal with Detail Preserving
Yu, Mei ; Kim, Yong-Deak ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 58~58
In this paper, detail-preserving fillers (DPFs) based on effective noise detections are proposed to remove random impulse noise in color image. Schemes of impulse noise detectors are given and their performances are analyzed and evaluated. DPFs based on effective noise detections are applied to clean noise and at the same time preserve edges and details in color image. In the experiments, all noisy images are generated by using Paint Shop Pro-5.0 software, which can produce color random impulse noise with variable height rather than salt-pepper noise. Experimental results show that the proposed adaptive filters perform better in removing noise as well as preserving edges and details.
The EFRA Algorithm for Congestion Avoidance using Connection Control Mechanism in ATM Networks
Kim, Dae-Il ; Lim, Hun-Ju ; Park, In-Kap ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 67~67
The main issues of explicit rate control algorithm for ABR (Available Bit Rate) service in ATM networks are the fair rate allocation, O(1) computational complexity, fast and excellent transient response. In this paper, we propose a new EFRA(Early Fair Rate Allocation) algorithm for ATM switches supporting ABR service. This new algorithm inherits above three main features of ERICA+(Explicit Rate Indication for Congestion Avoidance) algorithm, and improves the performance decay of an existing algorithms at the transient state. The EFRA algorithm uses connection control mechanism to prevent potential congestion, and achieves faster convergence time to the steady state. Thus, the peak queue lengths at the switches can further be reduced without any degradation in throughout, and the cell loss ratio is reduced. By using computer simulation, we compared EFRA with ERICA+, and demonstrated the effectiveness of new algorithm.
Fuzzy Control System Using Genetic Algorithm and Fusion Method
Na, Young-Nam ; Lee, Yun-Bae ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 77~77
A fuzzy controller has advantages over the existing linear controllers in some respects. However, it need membership functions and the control rules depend on heuristic knowledge of expertises. Hence it is possible that a desired performance of a fuzzy controller can not be guaranteed or easily degraded under some circumstances such as a change of plant parameter which expellers do not considered. Therefore, in this paper we tried to increase the controller's efficiency by adjusting the control rules and the parameters of the membership functions by using a genetic algorithm. We also proposed the Self-Organizing Fuzzy Controller which uses the Fusion Method in order to minimize the number of control rules and to construct the intuitive controller. For validation of the proposed algorithm, we design the Autonomous Guided Vehicle Controller, then apply to variant condition. As consequence, the proposed fuzzy controller had the minimized control rules. It's control efficiency was better than the existing fuzzy controllers due to the self-organization of parameters.
Spectral Domain Analysis of Uniaxial Superstrate-Loaded Rectangular Microstrip Patch on a Uniaxial Substrates
Yun, Joong-Han ; Chang, Seung-Ho ; Kwak, Kyung-Sup ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 91~91
The resonance characteristic of a uniaxial material superstrate-loaded microstrip structure on a uniaxial substrate is investigated. Dyadic Green's function is derived for selected uniaxial material and integral equations of electric fields are formulated. The electric field integral equations are discretized into the matrix form by applying Galerkin's moment method. The sinusoidal functions are selected as basis functions, which can give fast numerical convergence because they resemble in the actual standing wave on the patch. To verify the validity of numerical result, we compare our results with existing one and get a good agreement between them. From the numerical results, the resonant frequency and bandwidth of the uniaxial superstrate-loaded rectangular patch antennas are discussed.
Study on the Mechanism of Inter-gates Microwave Coupling and the Amplification Effect in Dual-gate FET's
Yang, Ki-Dug ; Kim, Sang-Tae ; Lee, Sang-Ho ; Ra, Keuk-Hwan ; Shin, Chull-Chae ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 98~98
The amplification effect in 2-cavity klystron is attributed to the electron bunching phenomenon obtained by the space modulation. In this paper a method which exhibits the same effect in a semiconductor with planar structure is proposed. The microwave coupling mechanism which exists between the channel of semiconductor and two gates of a dual-gate FET is analyzed, which has not been yet considered in the dual-gate FET circuit analysis. On the base of this analysis a new power amplification conception that a gain can be obtained at much higher frequency with a dual-gate FET haying low operation frequency is proposed. Microwave amplification phenomenon by the interactions between the space-wave and gates is theoretically inferred, and a qualitative analysis is carried out. Theoretical computation results are obtained by the numerical analysis using the least squares boundary residual method, a kind of variational method, and the eigenvalue problem analysis method. The validation and accuracy of the proposed concept and the method of analysis are confirmed by comparing the numerical results with the experimental results.
Design of Self-Oscillating Mixer with HEMT Nonlinear Characteristics.
Kim, Sang-Tae ; Rhee, Young-Chul ; Shin, Chul-Jae ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 119~119
In this paper, we have developed a Ka-band(26.5GHz) self oscillation mixer employing the second harmonic frequency generated with the nonlinear characteristics of HEMT. The designed Self-Oscillating Mixer is composed of the high stabilized series feedback dielectric resonant oscillator which operating frequency is the second harmomic signal as a self-oscillation signal and HEMT-gate mixer, Based upon the analyzing the nonlinear equivalent elements of HEMT, the Ka-band Self-Oscillating Mixer was biased at the pinch-off point and optimized the series feedback electric length of oscillator to maximize of second harmonic signal. and we gained the IF output signal with the double designed
stub to prevent a spurious oscillation and bandpass filter at output terminal. The designed Ka-band self-oscillating mixer applying LMDS downcoverter shows that the phase noise is -100dBc/Hz at the offset frequency of 100KHz and the average conversion gain turned to be 9dB within the IF frequencies ranging between 1.0GHz and 1.8GHz.
Design of a Totally Self-Checking CMOS Circuit
Kim, Jeong-Beom ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 128~128
Totally self-checking (TSC) circuit is a class of circuits which are used to detect faults concurrently with normal operation. This paper introduces a new method for designing self-checking static CMOS circuit. The designed circuit based on the proposed method can detect breaks and transistor stuck-on faults. The resulting circuit produces a valid code (00 or 11) on its output in the fault-free. Otherwise, this circuit produces all invalid code (01 or 10) on their outputs in the presence of such faults. The validity and effectiveness are verified through the HSPICE simulation.
New Designs for XOR and XNOR Circuits on the Transistor Level
Lee, Yong-Sup ; Kwak, Chol-Ho ; Kim, Jeong-Beom ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 134~134
In this paper, two new designs for XOR and XNOR circuits are proposed. The first circuit implements the XOR and XNOR functions with three transistors using depletion type MOSFET. The other one improves the performance of the first circuit but two more transistors are utilized. These XOR and XNOR circuits do not use additional control signal as complementary input. Computer simulations using HSPICE show that the proposed circuits have short propagation delay time and more driving capability.
Design of Programmable High Frequency Gm-C Universal Filter
Shin, Gun-Soon ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 142~142
This paper presents a 2nd-order programmable high frequency Gm-C universal filler which is operated with single power supply +5V, integrated in a
CMOS double-poly double-metal N-well process. The filter provides 4 selectable types lowpass, bandpass, highpass and bandstop filter, and composed of gain amplifier, gain controller. 2nd-order Gm-C universal filters,
controller, Q controller, mode selector, input/output buffer, voltage reference. Also the filter is programmed the voltage gain,
, Q by users for analog filter with cut off frequency, from several hundred KHz to several decade MHz. The designed total chip area is
, maximum power dissipation is 110mW, and maximum THD is -74.03dB in lowpass filter mode when input signal is 1MHz, 1Vp-p.
Design of Subharmonics Pumped Mixer Using Anti-Parallel Diode Pair
Jeung, Seung-Il ; Yoo, Jae-Moon ; Lee, Jong-Arc ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 157~157
In this paper, subharmonic mixer using anti-parallel diode pair is studied. Conventional mixers mix LO signal with RF signal, and obtain IF signal from the difference between LO and RF. Subharmonic mixers (SHP mixers) using APDP mix RF signal with the second harmonic of LO signal. Thus LO frequency composed with the conventional receiver is reduced by 1/2. The fabricated mixer showed 6.5 dB conversion loss, and 1 dB compression point was -8 dBm. At IF port, isolation of LO input vs. output and RF input vs. output are 76 dB, 30 dB respectively. At RF port isolation of LO input vs. output is 45dB, at LO port isolation is above 30 dB.
Development of In-process Tolerance Measurement System for Lathe Process -Roundness Measurement Algorithm of a Lathe Working Piece-
Heo, Ung ; Seo, Dong-Seon ; Choe, U-Yeong ; Kim, Hui-Nam ;
Journal of IKEEE, volume 4, issue 1, 2000, Pages 163~163
In this paper, we study a roundness measurement method for real-time monitoring the size of a working piece under lathe process. The roundness of a working piece can be evaluated by the difference between e theoretical and measured centers. Since the measured value contains all kinds of noises, we need a measurement algorithm which is robust against the noises. Here, we suggest three of the algorithms to determine the center and evaluate the performance of each algorithm under various noises. Under various noise the second method shows the most robust characteristics against the noises.