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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Transactions of The Korean Institute of Electrical Engineers
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The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 58, Issue 12 - Dec 2009
Volume 58, Issue 11 - Nov 2009
Volume 58, Issue 10 - Oct 2009
Volume 58, Issue 9 - Sep 2009
Volume 58, Issue 8 - Aug 2009
Volume 58, Issue 7 - Jul 2009
Volume 58, Issue 6 - Jun 2009
Volume 58, Issue 5 - May 2009
Volume 58, Issue 4 - Apr 2009
Volume 58, Issue 3 - Mar 2009
Volume 58, Issue 2 - Feb 2009
Volume 58, Issue 1 - Jan 2009
Selecting the target year
A Thermal Unit Commitment Approach based on a Bounded Quantum Evolutionary Algorithm
Jang, Se-Hwan ; Jung, Yun-Won ; Kim, Wook ; Park, Jong-Bae ; Shin, Joong-Rin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1057~1064
This paper introduces a new approach based on a quantum-inspired evolutionary algorithm (QEA) to solve unit commitment (UC) problems. The UC problem is a complicated nonlinear and mixed-integer combinatorial optimization problem with heavy constraints. This paper proposes a bounded quantum evolutionary algorithm (BQEA) to effectively solve the UC problems. The proposed BQEA adopts both the bounded rotation gate, which is simplified and improved to prevent premature convergence and increase the global search ability, and the increasing rotation angle approach to improve the search performance of the conventional QEA. Furthermore, it includes heuristic-based constraint treatment techniques to deal with the minimum up/down time and spinning reserve constraints in the UC problems. Since the excessive spinning reserve can incur high operation costs, the unit de-commitment strategy is also introduced to improve the solution quality. To demonstrate the performance of the proposed BQEA, it is applied to the large-scale power systems of up to 100-unit with 24-hour demand.
The Modeling of OverCurrent Relay using Dynamic Link Library
Seong, No-Kyu ; Seo, Hun-Chul ; Yeo, Sang-Min ; Kim, Chul-Hwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1065~1070
This paper presents the new technique of modeling using Dynamic Link Library(DLL) in ElectroMagnetic Transients Program - Restructured Version(EMTP-RV) in which we have simplified the procedures of OverCurrent Relay(OCR) modeling. The DLL function is designed to allow EMTP-RV users to develop advanced program model modules and interface them directly and intimately with the EMTP-RV engine. The modeled OCR is verified by simulating the various fault cases in the distribution system. Also, the performance for the modeling of OCR using DLL is compared with that of the method using the control components of EMTP-RV and using EMTP/MODELS. The results show the validity of modeled OCR and the effectiveness of the method using DLL function.
Protection Measure of Transmission Jumper Line by Gap Winds
Koh, Bong-Eon ; Pyo, Gwang-Chan ; Park, Jae-Hyung ; Kang, Bum-Young ; Jung, Hyun-Jong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1071~1077
Because several winds cause the a fault of transmission supply, KEPCO trys to protect the the trouble and supply the power stably. Kepco find out the weak mountains by winds and strengthen the power equipment annually. Power quality is the competition power in the international world and satisfy the customer using th power Therefore this paper deals with the fault relation between winds and transmission line.
Fast Estimation of Low Frequency Parameter for Real-Time Analysis in Wide Area Systems
Kim, Eun-Ju ; Shim, Kwan-Shik ; Kim, Yong-Gu ; Kim, Eui-Sun ; Nam, Hae-Kon ; Lim, Young-Chul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1078~1086
This paper presents a Fourier based algorithm for estimating the parameters of the low frequency oscillating modes. The proposed methods estimates various parameters(frequency, damping factor, mode magnitude, phase) by fitting Fourier spectrum and phase with a damped exponential cosine function. Dominant frequency is selected by taking frequency corresponding to the peak spectrum, and damping factor is estimated using the left/right spectra of Fourier spectrum. In addition, mode magnitude is calculated by the normalized peak spectrum, and phase is estimated from spectrum phase. Also, we introduce an accuracy index in order to determine the accuracy of the estimated parameters, and the index is calculated using the deviations of the peak spectrum and the left/right spectra. The parameter estimation methods proposed in this paper include very simple arithmetical processes, so the algorithms are simple and the calculation speed is very fast. The proposed methods are applied to test functions with two dominant modes. The results show that the proposed methods are highly applicable to low frequency parameter estimation.
A Study on Improvement of Capacity Payment using Fuzzy Theory in CBP Market
Kim, Jong-Hyuk ; Kim, Bal-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1087~1092
This paper presents a method for improvement of capacity payment in CBP(cost based pool) market. Capacity payments have been used as common mechanisms in various pools for compensating generators recognized to serve a for reliability purpose. Ideal pricing for capacity reserves by definition achieves a balance between economic efficiency and investment incentives. That is, prices must be kept close to costs, but not so low as to discourage investment. However, the price set is not easy. This paper concludes with market design recommendations that apply fuzzy theory for improvement of capacity payment. Following this model, market participants decided on their own based on their forecast to the market demand and the payment for it.
Optimal Electricity and Heat Production Strategies of Fuel Cell Device in a Micro-grid Energy System
Lee, Joo-Won ; Park, Jong-Bae ; Kim, Su-Duk ; Kim, Chang-Seop ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1093~1099
Alternative energy sources such as renewable energy like solar power systems, wind power systems, or fuel cell power systems has been the rising issue in the electrical power system. This paper discusses an economic study analysis of fuel cells in the korean electricity market. It includes the basic concept of a fuel cell and the korean electricity market. It also describes the need of renewable energy and how the fuel cell is connected with the local grid. This paper shows the impact of production and recovering thermal energy of a grid-connected fuel cell power system. The profit maximization approach has been structured including electrical power trade with the local grid and heat trade within the micro-grid. The strategies are evaluated using a local load that uses electric and thermal power which has different patterns between summer and winter periods. The solution algorithm is not newly developed one, but is solved by an application called GAMS. Results indicate the need and usefulness of a fuel cell power system.
An Analysis of Power System Stability(PSS) Effect with 135MVA Hydro Generator
Ok, Yeon-Ho ; Lee, Eun-Woong ; Byun, Ill-Hwan ; Oh, Sueg-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1100~1104
As national power consumption every year increases, the power plant which is in the process of planning tries to establish high-capacity generator. The power system tends to become a large size. With the progress of electronic components, the control systems of the generator have been digitalized and rapid-response control system is possible. However, the minute frequency vibration of grid occurred with the effect of rapid-response control system. To solve these problem, PPS(Power System Stability) has been introduced since 2004, and it has being installed and applied to the thermal and nuclear power plant which are high-capacity, over 800MVA. However the minute frequency vibration is gradually changed to the bigger frequency vibration by fast-action control system, and this regional frequency fluctuation might be diffused wide area. Therefore, it is applied to the hydro generator which is small with fast-action governor system, and it is necessary to control the minute frequency vibration to prevent to diffuse. In this paper, the effect will be proved by establishing PSS on the Hydro-Generator which has both digital excitation and governor system for the first time in Korea.
A Elicitation of Polynomial Equation of Thrust Coefficient for Linear Synchronous Motor by Experimental Design Method
Jang, Ki-Bong ; Pyo, Se-Ho ; Kim, Gyu-Tak ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1105~1109
This paper deals with a polynomial thrust equation of a permanent magnet linear synchronous motor that is considered by a skew and overhang effects of permanent magnet. The skew length, the overhang length, the width and height of permanent magnet, the teeth length and air-gap length which effect to the flux density of air-gap are selected as variables of the polynomial thrust equation. Polynomial thrust equation is elicited by the 6 parameters. The results are satisfied that the values by polynomial thrust equation are compared ones by using 3-dimensional finite element analysis and experiment.
A Study on the Ballast Design of a Inductively Coupled Plasma Light Source based on Oscillation Theory
Kim, Cherl-Jin ; Yim, Youn-Chan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1110~1115
We studied on the design of electrical parameters for ICP(Inductively Coupled Plasma) light sources which can be effective to improve the electrical power efficiency of it. These parameters were derivated from Barkhausen theory about the oscillating condition of a ballaster. The relationships of
and f-n were calculated theoretically and then these relationships were compared with the measured results about
and power depending to a discharge length(l) of ICP light source. Finally, we can see that a specific range of induced current depending to a discharge length would be necessary to minimize the change of magnetization inductance and driving frequency at driving.
Analysis of EMI Between Overlapped Railway Signalling Systems and Its Countermeasure
Kho, Young-Hwan ; Yoon, Sun-Ho ; Choi, Kyu-Hyoung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1116~1122
ATS(Automatic Train Stop) system makes train stop when it runs over the speed limit and ensure the safe operation of train. Seoul Metro line 2 in Korea, which started its passenger service in 1982, has adopted ATS system for its signaling system. The ATS system has only a train stop function at the time of emergency, and Seoul Metro is planning to replaced them with ATC(Automatic Train Control)/ATO(Automatic Train Operation) system which can provide the dedicated speed control for headway reduction and automatic operation of train. Until all the ATS system is replaced with the new ATC system, both systems are to operate simultaneously at the same metro line. In this situation, ATS system sometimes reveals improper operation: train stops suddenly without any obstacles in front of it. These emergency stops cause interruption of passenger service, and abnormal abrasion of wheels and rail. This paper makes it clear that these interruptions are caused by EMI phenomena between ATS on-board device and ATC wayside device : Signal current flowing in AF track circuit of ATC is turn out to be a EMI source that prevent normal operation of the ATS on-board device. Although the two systems have different frequency-ranges (ATS system has frequency range between
[kHz] and ATC system has frequency range between
[kHz]), it turned out that EMI phenomena appears between the both systems. This is investigated by measuring the output signal from ATS on-board device passing over ATC wayside device. The FFT(Fast Fourier Transform) analysis of the signal reveals that AF track circuit signal is transmitted to the ATS on-board device and induce noise causing improper operation. The countermeasures to the EMI phenomena are examined in three ways; blocking EMI transmission, enforcement of EMS (Electromagnetic Susceptibility) of ATS on-board device, and blocking the EMI source. It is suggested that the practical solution be blocking EMI source temporarily, that is breaking AF track circuit signal when the trains with ATS on-board device pass over it. To this purpose, TODS(Train Occupation Detection System) is developed, and has made a success in preventing the EMI problem of Seoul Metro line 2.
Development of Simulator for Wind Power Generation
Seo, Young-Ger ; Lee, Ji-Eun ; Ko, Jong-Sun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1123~1129
The main goal of this paper is to simulate a Doubly-Fed Induction Generator (DFIG), which is similar to a real system. Wind velocity data is applied to a 2D Lookup table as a speed reference for a turbine model. A real electric machine's parameters are put in the simulator to get some results of the real system. The Matlab have been generally used to simulate DFIG, but it has some differences from the real system and is difficult to implement. A Simplorer simulator, however, simplifies DFIG simulation. The turbine is directly connected with the DFIG to be close to the real system. The machine's rotor is excited and controlled by the discrete carrier modulated matrix converter. It is possible to retrieve important information, like a generated power and wind quality etc., from the simulator without a huge wind turbine.
Development of PMSG Wind Power System Model using Wind Turbine Simulator and Matrix Converter
Yun, Dong-Jin ; Han, Byung-Moon ; Cha, Han-Ju ; Li, Yu-Long ; Choi, Nam-Sup ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1130~1137
This paper describes a scaled model development of PMSG wind power system using wind turbine simulator and matrix converter. The wind turbine simulator, which consists of an induction motor with vector drive, calculates the output torque of a specific wind turbine using simulation software and sends the torque signal to the vector drive after scaling down the calculated value. The operational feasibility of interconnected PMSG system with matrix converter was verified by computer simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was conformed by experimental works with a laboratory scaled-model of wind power system. The simulation and experimental results confirm that matrix converter can be effectively applied for the PMSG wind power system.
Operational Analysis of Energy Storage System to Improve Performance of Wind Power System with Induction Generator
Lee, Ji-Heon ; Shim, Myong-Bo ; Lee, Hye-Yeon ; Han, Byung-Moon ; Yang, Seung-Chul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1138~1145
This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The output power of a wind power system changes irregularly according to the variation of wind speed. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The operational feasibility of the proposed model was verified by simulations with PSCAD/EMTDC and the feasibility of hardware implementation was confirmed by experimental works with a scaled hardware model. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.
Chemical Mechanical Polishing Characteristics of CdTe Thin Films for Application to Large-area Thin Film Solar Cell
Yang, Jung-Tae ; Shin, Sang-Hun ; Lee, Woo-Sun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1146~1150
Cadmium telluride (CdTe) is one of the most attractive photovoltaic materials due to its low cost, high efficiency and stable performance in physical, optical and electronic properties. Few researches on the influences of uniform surface on the photovoltaic characteristics in large-area CdTe solar cell were not reported. As the preceding study of the effects of thickness-uniformity on the photovoltaic characteristics for the large-area CdTe thin film solar cell, chemical mechanical polishing (CMP) process was investigated for an enhancement of thickness-uniformity. Removal rate of CdTe thin film was 3160 nm/min of the maximum value at the 200
of down force (pressure) and 60 rpm of table speed (velocity). The removal rate of CdTe thin film was more affected by the down force than the table speed which is the two main factors directly influencing on the removal rate in CMP process. RMS roughness and peak-to-valley roughness of CdTe thin film after CMP process were improved to 96.68% and 85.55%, respectively. The optimum process condition was estimated by 100
of down force and 60 rpm of table speed with the consideration of good removal uniformity about 5.0% as well as excellent surface roughness for the large-area CdTe solar cell.
Study on the Address Discharge Characteristics for the Improvement of the Mis-firing Problem in AC PDP
Jeon, Won-Jae ; Kim, Dong-Hun ; Lee, Seok-Hyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1151~1156
Unstable sustain discharges can occur at the bottom cells of the panel at high temperature. To solve this problem, the wall charge variation during an address period was investigated. A test panel of 7.5 inch XGA level was used and one green cell was measured. In order to realize operating condition equal to that of the bottom cells of 50 inch panel, the addressing stress pulses are applied. It seems that the resultant wall charge loss during address period increased with increase of stress time, temperature, pressure and Xe %. Wall charge loss increases with potential difference between scan electrode and address electrode, therefore wall charge loss can be minimized by the increase of scan voltage during address period.
Driving Method for Mis-discharge Improvement at Low Temperature in AC PDP
Kim, Gun-Su ; Lee, Seok-Hyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1157~1165
In AC-PDP, it is necessary to achieve high luminance efficiency, high luminance and high definition by adopting technologies such as high xenon concentration, MgO doping, and long gap. However, it is very difficult to apply above technologies because they make the driving voltage margin reduced. Especially, high Xe concentration technology for high efficacy makes not only the driving voltage margin reduced but also the stability of reset discharge decreased at low temperature. In this paper, we studied temperature and voltage dependent stability of reset discharge and present the experimental results of the discharge characteristics at low temperature. In addition, we suggested the mechanism of bright noise and black noise at low temperature. Finally, we proposed double reset waveform to improve the bright noise and descending scan time method to improve the black noise.
A Study on Design of Optimal Load Impedance for Broadband Characteristic Improvement of the Power Amplifier
Lee, Han-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1166~1173
In this paper, we studied on the power amplifier which has the output of the optimal to 100MHz-2GHz band. Optimal output power match was fabricated using the two types; one is the linear tapering and the other is the impedance transformer. In the case of output power match using linear tapering, output power was 35.35dBm at 2GHz and 31.41dBm at 100MHz. The other case of output match using impedance transformer, output power was 34.8dBm at 2GHz and 33.25dBm at 100MHz. Comparison of the results in the two cases, impedance transformer type present the improved results by l.84dB of output power.
Study of Transient Response in Non-uniform Plasma Layer with Optically-Controlled Microwave Pulses
Wang, Xue ; Choi, Yue-Soon ; Park, Jong-Goo ; Kim, Yong-K. ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1174~1179
In this paper we develop the characteristic of density on non-uniform plasma in different layer of the semiconductor with optically controlled microwave pulses. The transient response of the microwave pulses in different plasma layer has been evaluated by calculating the variation of the reflection function of dielectric microstrip lines. The lines has used under open-ended termination containing optically induced plasma region, which has illuminated a laser source. The characteristics impedances resulting from the presence of plasma are evaluated by the transmission line model. The analyzes the variation of transient response in a 0.01cm layer near the surface for frequency range from 1GHz to 128GHz. The diffusion length LD is larger than compared to the absorption depth
. The variation of characteristic response in plasma layer with microwave pulses which has in deferentially localized has been evaluated analytically.
New Portable System for Measuring the Spasticity of Injury in Central Nervous System
Song, Chul-Gyu ; Seo, Jeong-Hwan ; Han, Sang-Hyung ; Kim, Keo-Sik ; An, Yang-Su ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1180~1185
Spasticity is a velocity-dependent stretch reflex disorder of the body motor system developing after the injury of the central nervous system, in which certain muscles are continuously contracted involuntarily. Conventional methods such as the modified Ashworth scale, Spasm frequency scale, pendulum test and isokinetic dynamometer had some disadvantages: limitation in discriminating the increase of resistance, immovable and expensive device, not enough study parameters. Therefore, it is necessary to introduce clinically more useful instrument, which can produce objective data and are more convenient on spasticity measurement. Spasticity measuring methods were reviewed and a new measuring instrument was designed and introduced. The new measuring system is a portable spasticity-measurement system, which encompass various scopes of spasticity-related human signals such as electrophysiologic, kinematic and biomechanical data. Our device was designed in order to measure the joint angle, angular velocity, electromyographic signals and force. We suggest that this new system can diagnose the spasticity of the muscles, objectively.
Development of Miniaturized Textile Electrode for Measuring Heart Electric Activity
Lee, Young-Jae ; Lee, Jeong-Whan ; Yang, Heui-Kyung ; Lee, Joo-Hyeon ; Kang, Da-Hye ; Cho, Hyun-Seung ; Ahn, Ihn-Seok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1186~1193
Wearable ECG monitoring is regarded as one of the most essential part in the ubiquitous healthcare environment and subsequently day-life monitoring of a heart condition has been pursued especially for the elder people. However, there are many problems to accomplish this task such as; i) implementation of long-term monitoring device, ii) development of non-irritating electrode on skin and iii) stable signal acquisition. With these aims, we have focused on implementing a non-irritating electrode with an endurable monitoring device for day-life. To accomplish our tasks, we basically developed four different types of textile electrodes that are adapted by both shape and the composed material; flat or convex shape and Ag-conductive paste material or not. It turns out to be that a convex shape and Ag-paste textile electrode has the best performance in terms of both signal-to-noise ratio (SNR) and Impedance/Phase characteristics. Furthermore, ECG amplifier (35
35 mm) has developed to resolve the ECG signal and transfer the signal to desktop computing device or portable one by RF serial communication.
A Study on Performance Enhancement of Period Detection in Pulse Wave
Lee, Hyun-Min ; Kim, Dong-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1194~1199
Heart rate may be a very important parameter in human health. To extract heart rate, the electrocardiogram(ECG) is commonly used. But the ECG acquisition procedure is very complex. On the other hand, the acquisition of pulse wave or photoplethysmogram(PPG) is very easy. However, the peak of PPG is not so sharp as ECG. This study tries to enhance the performance of peak detection in PPG signal. The method uses the average slopes around the main peak. The crossing point of the increasing and the decreasing slopes is selected as the peak point of heart rate period. The proposed method showed smoothed heart rate graph and reduced irregularity in heart rate values.
A New Method of Plaque Scoring and Database Implementation
Shin, Seung-Won ; Kim, Kyeong-Seop ; Lee, Sun-Ju ; Kim, Dong-In ; Kim, Kee-Deog ; Park, Won-Se ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1200~1206
In this study, a new method of dental plaque scoring is proposed by adopting new criteria to divide the tooth surface with utilizing the geometrical features of a tooth color image. For the possible clinical usage of our new plaque scoring system, GUI(Graphic User Interface) system is also implemented to estimate the numerical plaque index for a specific tooth by designing the supplementary database management module that handles dental plaque scores.
Image Segmentation of Teeth Region by Color Image Analysis
Lee, Seong-Taek ; Kim, Kyeong-Seop ; Yoon, Tae-Ho ; Kim, Kee-Deog ; Park, Won-Se ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1207~1214
In this study, we propose a novel color-image segmentation algorithm to discern the teeth region utilizing RG intensity and its relevant RGB histogram features with resolving the variations of its maximum intensity in terms of peaks and valleys. Tooth candidates in a CCD image are first extracted by applying RGB color multi-threshold levels and consequently the successive morphological image operations and a Sobel-mask edge processing are performed to resolve the teeth region and its contour.
Synchronization of Chaotic Secure Communication Systems with Interval Time-varying Delays
Kwon, Oh-Min ; Park, Ju-Hyun ; Lee, Sang-Moon ; Park, Myeong-Jin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1215~1222
In this paper, a method of designing a controller which ensures the synchronization between the transmission and the reception ends of chaotic secure communication systems with interval time-varying delays is proposed. To increase communication security, the transmitted message is encrypted with the techniques of N-shift cipher and public key. And to reduce the conservatism of the stabilization criterion for error dynamic system obtained from the transmitter and receiver, a new Lyapunov-functional and bounding technique are proposed. Through a numerical example, the effectiveness of the proposed method is shown in the chaotic secure communication system.
Design of Radial Basis Function with the Aid of Fuzzy KNN and Conditional FCM
Roh, Seok-Beon ; Oh, Sung-Kwun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1223~1229
The performance of Radial Basis Function Neural Networks depends on setting up the Radial Basis Functions over the input space which are the important design procedure of Radial Basis Function Neural Networks. The existing method to initialize the location of the radial basis functions over the input space is to use the conditional fuzzy C-means clustering. However, the researchers which are interested in the conditional fuzzy C-means clustering cannot get as good modeling performance as they expect because the conditional fuzzy C-means clustering cannot project the information which is extracted over the output space into the input space. To compensate the above mentioned drawback of the conditional fuzzy C-means clustering, we apply a fuzzy K-nearest neighbors approach to project the auxiliary information defined over the output space into the input space without lose of the information.
The Design of Granular-based Radial Basis Function Neural Network by Context-based Clustering
Park, Ho-Sung ; Oh, Sung-Kwun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1230~1237
In this paper, we develop a design methodology of Granular-based Radial Basis Function Neural Networks(GRBFNN) by context-based clustering. In contrast with the plethora of existing approaches, here we promote a development strategy in which a topology of the network is predominantly based upon a collection of information granules formed on a basis of available experimental data. The output space is granulated making use of the K-Means clustering while the input space is clustered with the aid of a so-called context-based fuzzy clustering. The number of information granules produced for each context is adjusted so that we satisfy a certain reconstructability criterion that helps us minimize an error between the original data and the ones resulting from their reconstruction involving prototypes of the clusters and the corresponding membership values. In contrast to "standard" Radial Basis Function neural networks, the output neuron of the network exhibits a certain functional nature as its connections are realized as local linear whose location is determined by the values of the context and the prototypes in the input space. The other parameters of these local functions are subject to further parametric optimization. Numeric examples involve some low dimensional synthetic data and selected data coming from the Machine Learning repository.
Node Selection Algorithm for Cooperative Transmission in the Wireless Sensor Networks
Gao, Xiang ; Park, Hyung-Kun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1238~1240
In the wireless sensor network, cooperative transmission is an effective technique to combat multi-path fading and reduce transmitted power. Relay selection and power allocation are important technical issues to determine the performance of cooperative transmission. In this paper, we proposed a new multi-relay selection and power allocation algorithm to increase network lifetime. The proposed relay selection scheme minimizes the transmitted power and increase the network lifetime by considering residual power as well as channel conditions. Simulation results show that proposed algorithm obtains much longer network lifetime than the conventional algorithm.
Efficient Signal Reordering Unit Implementation for FFT
Yang, Seung-Won ; Lee, Jang-Yeol ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1241~1245
As FFT(Fast Fourier Transform) processor is used in OFDM(Orthogonal Frequency Division Multiplesing) system. According to increase requirement about mobility and broadband, Research about low power and low area FFT processor is needed. So research concern in reduction of memory size and complex multiplier is in progress. Increasing points of FFT increase memory area of FFT processor. Specially, SRU(Signal Reordering Unit) has the most memory in FFT processor. In this paper, we propose a reduced method of memory size of SRU in FFT processor. SRU of 64, 1024 point FFT processor performed implementation by VerilogHDL coding and it verified by simulation. We select the APEX20KE family EP20k1000EPC672-3 device of Altera Corps. SRU implementation is performed by synthesis of Quartus Tool. The bits of data size decide by 24bits that is 12bits from real, imaginary number respectively. It is shown that, the proposed SRU of 64point and 1024point achieve more than 28%, 24% area reduction respectively.
Reproducibility analysis of surface EMG spike variables during isometric voluntary contraction of the biceps brachii muscle
Lee, Jin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 6, 2009, Pages 1246~1254
The reproducibility of initial value and change over time of surface EMG spike variables(MSA, MSF, MSS, MSD) was investigated in the biceps brachii muscle of 11 healthy subjects. Surface EMG signals were recorded during sustained isometric voluntary contractions for 30 seconds at three contraction levels, 20%, 50%, and 80%MVC, respectively. Each contraction was repeated three times in each of three different days for a total of nine contractions and 99 contractions per %MVC level across the eleven subjects. A total of 297 EMG signals across the different trials, days, subjects, and %MVC levels was saved for the subsequent analysis. The degree of reproducibility was investigated using the intraclass correlation coefficient(ICC) and the standard error of the mean(SEM) based upon the analysis of variance(ANOVA), Results for intercept showed higher reproducibility of the spike variables with about 60%-98% ICC than the variable(ARV, MNF) which had been analyzed before in other researches. And results for slope showed poor reproducibility of the spike variables with about 30%-70% ICC and they were comparable with the variables of other researches.