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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 1, Issue 1 - Dec 1997
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A Monolithic Integration with A High Density Circular-Shape SOI Microsensor and CMOS Microcontroller IC
Mike, Myung-Ok ; Moon, Yang-Ho ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 1~10
It is well-known that rectangular bulk-Si sensors prepared by etch or epi etch-stop micromachining technology are already in practical use today, but the conventional bulk-Si sensor shows some drawbacks such as large chip size and limited applications as silicon sensor device is to be miniaturized. We consider a circular-shape SOI(Silicon-On-Insulator) micro-cavity technology to facilitate multiple sensors on very small chip, to make device easier to package than conventional sensor like pressure sensor and to provide very high over-pressure capability. This paper demonstrates the cross-functional results for stress analyses(targeting
deflection and 100MPa stress as maximum at various applicable pressure ranges), for finding permissible diaphragm dimension by output sensitivity, and piezoresistive sensor theory from two-type SOI structures where the double SOI structure shows the most feasible deflection and small stress at various ambient pressures. Those results can be compared with the ones of circular-shape bulk-Si based sensor
. The SOI micro-cavity formed the sensors is promising to integrate with calibration, gain stage and controller unit plus high current/high voltage CMOS drivers onto monolithic chip.
Influence of Parasitic Resistances and Transistor Asymmetries on Read Operation of High-Resistor SRAM Cells
Choi, Jin-Young ; Choi, Won-Sang ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 11~18
By utilizing the technique to monitor the DC cell node voltages through circuit simulation, degradation of the static read operating margin In high load-resistor SRAM cell was examined, which is caused by parasitic resistances and transistor asymmetries in this cell structure. By selectively adding the parasitic resistances to an ideal cell, the influence of each parasitic resistance on the operating margin was examined, and then the cases with parasitic resistances in pairs were also examined. By selectively changing the channel width of cell transistors to generate cell asymmetry, the influence of cell asymmetry on the operating margin was also examined. Analyses on the operating margins were performed by comparing the supply voltage values at which two cell node voltages merge to a single value and the differences of cell node voltages at VDD=5V in the simulated node voltage characteristics. By determining the parasitic resistances and the transistor asymmetries which give the most serious effect on the static read-operation of SRAM cell from this analysis based on circuit simulated, a criteria was provided, which can be referred in the design of new SRAM cell structures.
A Study on Design of Optimal Satellite-Tracking Antenna
Kim, Dong-Wan ; Jeong, Ho-Seong ; Hwang, Hyun-Joon ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 19~30
In this paper we design the optimal satellite-tracking antenna
control system using genetic algorithms. To do this, we give gain and dynamics parameters to the weighting functions and apply genetic algorithms with reference model to the optimal determination of weighting functions and design parameter
that are given by Glover-Doyle algorithm which can design
controller in the state space. These weighting functions and design parameter
are optimized simultaneously in the search domain guaranteeing the robust stability of closed-loop system. The effectiveness of this satellite-tracking antenna
control system is verified by computer simulation.
Design and Performance Analysis of a Parallel Optimal Branch-and-Bound Algorithm for MIN-based Multiprocessors
Yang, Myung-Kook ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 31~46
In this paper, a parallel Optimal Best-First search Branch-and-Bound(B&B) algorithm(pobs) is designed and evaluated for MIN-based multiprocessor systems. The proposed algorithm decomposes a problem into G subproblems, where each subproblem is processed on a group of P processors. Each processor group uses tile sub-Global Best-First search technique to find a local solution. The local solutions are broadcasted through the network to compute the global solution. This broadcast provides not only the comparison of G local solutions but also the load balancing among the processor groups. A performance analysis is then conducted to estimate the speed-up of the proposed parallel B&B algorithm. The analytical model is developed based on the probabilistic properties of the B&B algorithm. It considers both the computation time and communication overheads to evaluate the realistic performance of the algorithm under the parallel processing environment. In order to validate the proposed evaluation model, the simulation of the parallel B&B algorithm on a MIN-based system is carried out at the same time. The results from both analysis and simulation match closely. It is also shown that the proposed Optimal Best-First search B&B algorithm performs better than other reported schemes with its various advantageous features such as: less subproblem evaluations, prefer load balancing, and limited scope of remote communication.
Effects of Atmospheric Turbulence on the Optical Satcom Link between Stratospheric Sky Station and Earth Station
Jung, Jin-Ho ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 47~54
Today's communication needs the super high-speed data transmission system to send many data rapidly, correctly, and simultaneously because of the increase of internet use, the demand of multimedia service and so on. Before long, the super high data service will be offered us by a satellite called platform which will be located at stratosphere of 20[km]over earth. It is possible to build the optical wireless communication networks which have the high data-tarrying capacity because this system use a laser. But, there are many problems to overcome because it make use of the atmospheric space as transmission channel. In this paper, therefore, we study up on the relations of data rates, bit error rates, and turbulent effects of atmosphere to present the effects of atmosphere to present the effects of atmospheric turbulence on the optical satcom link.
Rubust Vector Control of an Induction Motor without Speed Sensor
Park, Tae-Sik ; Kim, Seong-Hwan ; Kim, Nam-Jeung ; Yoo, Ji-Yoon ; Park, Gwi-Tae ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 55~63
The purpose of this paper is to realize robust vector control of an induction motor without speed sensor. In order to do it, the speed of an induction motor is estimated using model reference adaptive system(MRAS) and two rotor flux observers which have robustness to the parameter variation are employed as the reference model and the adjustable model in MRAS speed estimator. The MRAS-based overall control scheme has been implemented on 2.2kW induction motor control system and it is verified that the proposed speed sensorless control scheme is more stable and robust than the conventional schemes.
Performance Improvement of an Induction Motor in Low Speed Region
Kim, Seong-Hwan ; Park, Tae-Sik ; Kim, Nam-Jeung ; Yoo, Ji-Yoon ; Park, Gwi-Tae ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 64~72
Since the average speed calculated with encoder pulses inevitably has time delay, the control performance as well as the system stability is deteriorated. especially at the low speed region. Additionally, the distorted inverter output voltage due to the dead time effects and the forward voltage drops of the VSI (Voltage Source Inverter) causes torque ripples and their effects are more severe at the low speed operation of an induction motor. In this paper, an accurate speed estimation method using Kalman Filter Algorithm is presented to improve the performance of an induction motor speed control with a low precision encoder at low speed legion. The dead time effects and the forward voltage drops of the VSI are feedforwardly compensated to produce an exact inverter output voltage.
Performance Analysis of CSMA/CD in Radio Environment with Capture Effect
Sa, Ju-Hee ; Hyun, In-Bok ; Kwak, Kyung-Sup ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 73~82
In this paper we analyzed, using Markov modeling, the performance of CSMA/CD over the wireless channel which is characterized by near-far effect, shadowing and Rayleigh fading. The analysis shows that throughput of CSMA/CD is degraded by channel error. However, if capture effect which arises from the randomness of power level of received signal due to the fading phenomena of electromagnetic waves is taken into consideration, the system performance is much improved and the system stability is also made better.
Out-of-Sequence Performance of Multi-Path ATM Switching Fabrics
Jung, Youn-Chan ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 83~92
Multipath ATM switch architectures have the potential to accommodate easily the design of high-speed and large capacity ATM switches which can handle a very large amount of switching throughputs. However, the multipath architecture inevitably encounters out-of-sequence problems. We propose a multipath switch model to analyze the out-of-sequence phenomenon. And we analyze the out-of-sequence performance dependency on the architecture parameters : the number of multipath, the trunk utilization, the switch size, and the number virtual channels/trunk. Indexing terms : ATM switch, Multipath archltecture, Out-of-sequence performance, Cell sequence integrity, Analytical model.
Segmentation of Color Image by Subtractive and Gravity Fuzzy C-means Clustering
Jin, Young-Goun ; Kim, Tae-Gyun ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 93~100
In general, fuzzy C-means clustering method was used on the segmentation of true color image. However, this method requires number of clusters as an input. In this study, we suggest new method that uses subtractive and gravity fuzzy C-means clustering. We get number of clusters and initial cluster centers by applying subtractive clustering on color image. After coarse segmentation of the image, we apply gravity fuzzy C-means for optimizing segmentation of the image. We show efficiency of the proposed algorithm by qualitative evaluation.
Performance Analysis of Caching Instructions on SVLIW Processor and VLIW Processor
Ji, Sung-Hyun ; Park, No-Kwang ; Kim, Suk-Il ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 101~110
SVLIW processor architectures can resolve resource collisions and data dependencies between the instructions while scheduling VLIW instructions at run-time. As a result, long NOP word instructions can be removed from the object code produced for the processor. Thus, the occurrence of cache misses on the SVLIW processor would be lesser than that on the same cache size VLIW processor. Less frequent cache misses on the SVLIW processor would incur less frequent memory access, and thus, the total execution cycles to complete an application would be shortened compared with cases on the VLIW processor. Such a feature eventually compromises effects of longer instruction pipeline stages than those of the VLIW processor. In this paper, we formulate and compare two execution cycle models of the two architectures. A simulation results show that the longer memory access cycles when cache miss occurs, the total execution cycles of SVLIW processor would be shorter than those of VLIW processor.
A Study on the Construction of Multiple-Valued Logic Functions by Edge-Valued Decision Diagram
Han, Sung-Il ; Choi, Jai-Sock ; Park, Chun-Myoung ; Kim, Heung-Soo ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 111~119
This paper presented a method of extracting algorithm for Edge Multiple-Valued Decision Diagrams(EMVDD), a new data structure, from Binary Decision Diagram(BDD) which is resently used in constructing the digital logic systems based on the graph theory. And we discussed the function minimization method of the n-variables multiple-valued functions. The proposed method has the visible, schematical and regular properties.
Analysis of Data Rate on Optical Communication Links between Geo-Satellite and Earth Station
Han, Jong-Seok ; Jung, Jin-Ho ; Kim, Yung-Kwon ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 120~137
Han's model, which is able to analyze optical communication between earth station and geo-satellite as a function of atmospheric conditions and elevation angles. is presented. In Han's model, atmospheric conditions are roughly classified into six basic types; clear sky, cloud, haze, fog, rain and snow. Data rate satisfying for the BER below
is analyzed by Han's model in case of up-link and down-link, respectively. Data rate is more limited by up-link than by down-link because the pointing loss caused by atmosphere on the up-link is greater than the spatial coherence degradation caused by atmosphere on the down-link.
A study of the performance improvement of atmospheric optical communication for realization of optical satellite communication and optical radio LAN
Kim, Yung-Kwon ; Jung, Jin-Ho ; Kim, Jae-Pyung ; Kim, In-Ho ; Hong, Kwon-Eui ; Han, Jong-Seok ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 138~155
Wireless optical communication is able to obtain high antenna gain as well as utilize to transmit the high-speed information with large capacity than the RF communication. However, the propagation path (atmosphere) is considered as an attenuator occured turbulence, absorption and scattering. These undesired phenomena diminish the amount of light that is collected at the receiver. To evaluate the effect of the atmospheric turbulance and scattering, this paper perform the ground-to-ground wireless optical LAN experiment by using the (2,1,6) convolutional coder and Viterbi decoder, and analyze numerically the earth-station antenna diameter due to the propagation path condition and upstream/downstream link.
The Effects of Turbulent Atmosphere on Terrestrial Optical ASK Communication Systems
Hong, Kwon-Eui ; Kim, June-Hwan ; Jung, Jin-Ho ; Kim, Yung-Kwon ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 156~163
Since the wireless optical communications system transmits informations through the atmosphere, it is subject to many effects of the constituent materials of atmosphere. The turbulence effect always exists in both clear and cloudy days. It causes a beam wandering, breathing, and scintillation. These disadvantageous phenomena degrade the performance of an optical communications system. In this paper, I designed a refractive index measuring system and subcarrier ASK optical communications system. Through this system I measured refractive index in May and in August. From these measurements, the minimum value of the refractive index in these period was about
at night time and the maximum value was about
at day time. The refractive index structure parameter. BER(bit error rate), and the burst length were measured simultaneously in these measurements. the theoretically predicted BER and the measured values showed a good agreement.
The Design and Implementation of CE-OQPSK using NLF for Wideband PCS
Bang, Sung-Il ; Jang, Hong-Ju ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 164~175
In this paper, the CE-OQPSK that has constant envelope was designed for applying PSK to the nonlinear amplifier so as to improve power efficiency. For this realization. ROM and D/A converter that have relative low power consumption were used. As a result of comparing the PSD (Power spectrum density) of CE-OQPSK with that of conventional OQPSK through simulation for estimating the performance. In case of correlation factor
= 0.707. the improvement of bandwidth efficiency of 5% and 20% is achieved in the main lobe and the sidelobe, respectively. And, in case additional bandwidth-limiting-filter is added, it can be shown that the PSD of CE-OQPSK meet the FCC wireless LAN spectrum specification.
The Behavior of TCP over ATM with limited bandwidth
Lee, Jin-Woo ; Park, Ki-Tae ; Kim, Jin-Tae ; Kim, Hyung-Lae ; Park, In-Kap ;
Journal of IKEEE, volume 1, issue 1, 1997, Pages 176~184
The Asynchronous Transfer Mode(ATM) networks are being adopted as backbones over various parts of Internet. Also, TCP is one of the most widespread transport protocols, nowdays. It can be used with ATM. But, TCP shows poor end-to-end performance on ATM networks. Effective throughput of TCP over ATM can be quite low when cells are dropped at the congested ATM switch. The low throughput is due to wasted bandwidth as congested link transmits cells from corrupted packets. This paper examines the behavior of TCP over ATM with limited bandwidth in a broadband environment. As multiple VBR sources occupies most of the available bandwidth, there has been a starvation effect, so TCP sources couldn't get the chance of transmitting data. Also, throughput is proportional to the amount of buffer.