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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
Performance Improvement using Auxiliary Converter on HVDC System
Kim, Dong-Hee ; Lee, Hwa-Chun ; Park, Sung-Jun ; Nam, Hae-Kon ; Choi, Joon-Ho ; Kim, Kwang-Heon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 217~224
This paper presents a new AC/DC converter scheme for HVDC system to achieve a high power factor operation. The new AC/DC converter consists of two 12-pulse bridge converters in series: the primary and auxiliary converters. Ignition angles of the main and auxiliary converters are controlled independently to maintain the nominal DC voltage and control auxiliary voltage. The resulted DC voltage obtained by superimposing the above two phase modulated voltages can be controlled very rapidly over a wide range, and a high power factor operation is achieved. Performance improvements in power factor and harmonic distortion are validated by theoretic derivations and experiments with prototype HVDC system. With the proposed converters, investment for reactive power compensation and filter in HVDC system can be saved significantly.
Study of the Applicability of the Carson Line Model for the Series Reactance Calculation of the Power Feeding Lines with no Ground Return
Chung, Sang-Gi ; Kwon, Sam-Young ; Chang, Sang-Hoon ; Jang, Dong-Uk ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 225~231
In this paper, it is shown that Carson's equation can still be applied for the calculation of the series reactance of transmission lines with no ground return current as well as the one with ground return. It is proved in the following method. First two voltage drop equations for three-phase three wire transmission line are derived, one without considering ground return and the other using Carson's equation. The impedance matrix of the two equations are different from each other. But if we put the condition of zero ground current,
, those two equations becomes the identical equations. Therefore even a transmission line is not grounded, its line parameters can still be obtained using the Carson's equation. It has been confused whether or not Carson's equation can be used for an ungrounded system. It is because where ever Carson's equation is shown in the book, it also says that the system has ground return current paths as a premise. It is also verified with EMTP studies on the test circuit.
Analysis of Flicker Mitigation Effects using IEC Digital Flickermeter based on Matlab/Simulink Simulation
Jung, Jae-Ahn ; Cho, Soo-Hwan ; Kwon, Sae-Hyuk ; Jang, Gil-Soo ; Kang, Moon-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 232~238
Flicker, also known as voltage fluctuation, is a newest problem of power quality issues, because it is caused by nonlinear loads such as electrical arc furnace and large-scale induction motor, which are country-widely used as the heavy industries of a country develop. An international standard, International Electrotechnical Commission (IEC) 61000-4-15, was published in 1997 and revised in 2003. With increasing concerns about flicker, its mitigation methods have been also studied. General countermeasures for flicker are divided into three categories: a) enhancing the capacity of supplying system, b) Series elements including series reactor and series capacitor and c) power electronic devices including static VAR compensator (SVC) and static synchronous compensator (STATCOM). This paper introduces how to mitigate the voltage flicker at the point of common coupling (PCC) and presents how to simulate and compare the flicker alleviating effects by each mitigation method, using IEC flickermeter based on the Matlab/Simulink program.
A Study on the Estimation Methodology for the Stand-by Energy Savings of Televisions Using Learning Curves and Diffusion Models
Kim, Jung-Hoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 239~241
In this paper, an estimation methodology for stand-by energy savings of electric appliances is proposed and some case studies are carried out for televisions. The methodology is based on learning curves and diffusion models, which are able to explain the market characteristics such as market prices and the diffusion speed. Some models were developed to estimate power and energy savings for high-efficient appliances and these model have been used broadly. These models are also applied to this study and modified to estimate stand-by energy savings.
The Mechanical and Electrical behavior Changes of Overhead Conductor due to Forest Fire and Agents
Jang, Young-Ho ; Kim, Byung-Geol ; Kim, Shang-Shu ; Han, Se-Won ; Kim, Jin-Han ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 242~247
Forest Fire can cause a serious damage to overhead conductors. Therefore, the detailed investigation for the changes of mechanical and electrical properties of damaged conductors should be carried out to understand the effect of forest fires on conductors. This is very much important to maintain transmission line safely. Oxidation of overhead conductor was increased with temperature and time(maximum time : 30min). Conductivity of Al conductor was decreased by Agents. The detailed will be given in the text.
Power Line Channel Model Considering Adjacent Nodes with Reduced Calculation Complexity due to Multipath Signal Propagation and Network Size Using Infinite Geometric Series and Matrices
Shin, Jae-Young ; Jeong, Ji-Chai ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 248~255
We proposed a power line channel model. We adopted advantages of other power line channel models to calculate channel responses correctly and simply. Infinite geometric series reduced the calculation complexity of the multipath signal propagation. Description Matrices were also adopted to handle the network topology easily. It represents complex power line network precisely and simply. Newly proposed model considered the effect of the adjacent nodes to channel responses, which have been not considered so far. Several simulations were executed to verify the effect of the adjacent nodes. As a result we found out that it affected channel responses but its effect was limited within certain degree.
An Approach to Assessment of the Value of Black Start Service
Lee, Jeong-Ho ; Oh, Tae-Kyoo ; Kang, Dong-Joo ; Ok, Ki-Youl ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 256~263
For the power system to keep in a stable operating state, sufficient ancillary services must be available to respond to credible contingency events and return the power system to a satisfactory operating state in the case of contingencies as well as blackout events within specified predefined limits. The logical and reasonable bases of valuing and pricing the ancillary services are required to reach the common ground among market participants. The total amount of black start service transactions is quite small compared to the total ancillary service transactions as well as energy market transactions. Black start services must be provided as one of the ancillary services in the deregulated electricity market. In order to procure and remunerate black start services, it is necessary to quantify the value of the black start sources within the power system. In this paper, an approach to assess the value of the black start service is presented based on the cost-of-service solution. Financial simulation of the influence on market participants for the proposed approach on the service is carried out. The cost of the black start service is allocated in accordance with the principle of "causer pays", and the cost is shared by the producers and consumers equally that created the requirement for the service. Under the present electricity market, the mechanism to recover the cost is not implemented, a new approach to the ancillary services to provide incentive for the service providers has to be studied in the near future.
A Study on the Selection of Slack Bus at Application of Marginal Loss-Factor in a Competitive Electricity Market
Kim, Sang-Hoon ; Lee, Kwang-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 264~269
Marginal Loss Factor(MLF) is represented as the sensitivity of transmission loss, which is computed from the change of the generation at slack bus by the change of the load at the arbitrary bus. The MLF dependent on the selection of slack bus is one of the key factors affecting nodal pricing, Genco's profits, social welfare(SW) and Nash Equilibrium in a competitive electricity market. This paper addresses the methodology of slack bus selection by using Cournot model of Cost Based Pool market. Numerical results from sample cases show that the slack bus of MLF of the highest average is beneficial from the view points of SW.
A Study on the Vibration and Efficiency Characteristics of PMLSM According to Permanent Magnet Arrangement
Lee, Dong-Yeup ; Lee, Seung-Hoon ; Jang, Ki-Bong ; Kim, Gyu-Tak ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 270~277
This paper deals with a vibration and efficiency characteristics of Permanent Magnet Linear Synchronous Motor according to the PM arrangement. The generated force such as the thrust, detent force, normal force and lateral force are compared with analysis values and experimental ones. Furthermore characteristics of vibration and efficiency are estimated by experiments.
Evaluation of Global Force and Interaction Body Force Density in Permanent Magnet Employing Virtual Air-gap Concept
Lee, Se-Hee ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 278~284
The global force and interaction body force density were evaluated in permanent magnets by using the virtual air-gap scheme incorporating the finite-element method. Until now, the virtual air-gap concept has been successfully applied to calculate a contact force and a body force density in soft magnetic materials. These force calculating methods have been called as generalized methods such as the generalized magnetic charge force density method, the generalized magnetizing current force density method, and the generalized Kelvin force density method. For permanent magnets, however, there have been few research works on a contact force and a force density field. Unlike the conventional force calculating methods resulting in surface force densities, the generalized methods are novel methods of evaluating body force density. These generalized methods yield the actual total force, but their distributions have an irregularity, which seems to be random distributions of body force density. Inside permanent magnets, however, a smooth pattern was obtained in the interaction body force density, which represents the interacting force field among magnetic materials. To evaluate the interaction body force density, the intrinsic force density should be withdrawn from the total force density. Several analysis models with permanent magnets were tested to verify the proposed methods evaluating the interaction body force density and the contact force, in which the permanent magnet contacts with a soft magnetic material.
Comparative Analysis of Offset Voltage PWM and
PWM Method for 3 Phase Matrix Converter
Cha, Han-Ju ; Kim, Woo-Jung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 285~291
In this paper, comparative analysis of offset voltage PWM method and
PWM method for three-phase matrix converter is addressed by using a simple analytical and graphical method. Offset voltage PWM method calculates PWM patterns in terms of offset voltage and variable slope of carrier, and it simplifies matrix converter modulation algorithm significantly.
PWM method generates patterns by using two phases and maintaining a remaining phase to base phase, and it is implemented in the industrial products. The most important performance criterion of modulation method is a magnitude of current ripples and it is analytically modelled. The graphical illustration of theses complex multivariable functions make per-carrier cycle and per fundamental cycle behavior of two PWM methods understood. Two modulation methods are analysed with the analytical formulas and graphics, and the analysis shows offset voltage PWM method is superior to
PWM method with respect to input current ripples and output voltage ripples.
Study on the LED BLU Driving Circuit with a Local-dimming Structure
Park, Yu-Cheol ; Kim, Hee-Jun ; Chae, Gyun ; Baek, Ju-Won ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 292~300
This paper presents an LED BLU driving circuit with a local-dimming structure. The efficiency of the proposed LED driver has been improved by parallel driving 8 serial-connected LED arrays. It employed the soft-switching boost converter topology to reduce the switching power loss of the hard switching boost converter. Soft- and hard-switching converters have the same structure except that the free-wheeling diode in the hard-switching converter is replaced with the n-channel MOSFET in the soft-switching one. The proposed boost converter was compared with the hard switching converter. The soft-switching converter reveals superior ripple and efficiency. A smaller inductance can be used for the soft-switching converter contrasting to the hard-switching one. We also studied on an over-voltage protection circuit of the output of the driver at the no load condition. The protection circuit was applied to the proposed driver, and its operation was confirmed by experiment. Using a local-dimming technique, power consumption of LCD BLUs can be reduced as low as possible according to the brightness of its image.
Current Balance Controller for Parallel Boost Converter with Peak Current Mode Control
Park, Jong-Gyu ; Jang, Eun-Sung ; Kang, Sin-Chul ; Shin, Yong-Hwan ; Shin, Hwi-Beom ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 301~307
In the paralleled converter module with peak current mode control, current imbalance appears when the voltage controllers with integral control of converter module are not exactly identical. In this paper, the voltage controller is designed to equal the current command of each converter module using the current command bus. The current balance controller is also proposed to balance the average currents of converter modules with imbalaced inductance. It is designed to have good transient response. Proposed method is implemented with the paralleled 2-module and 4-module boost converters with imbalanced inductance. Experimental results verify the performance of current share during both steady and transient states of converter.
Field Reliability Analysis of S-Bond of AF Track Circuit for Automatic Train Control System
Choi, Kyu-Hyoung ; Rho, Young-Whan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 308~313
This paper presents a reliability analysis of S-bonds for AF track circuits, which detect train movement and transmit a speed control signal to the train. Field survey shows that S-bonds are exposed to very large vibrations transferred from rail, and suffer from frequent failures when they were installed on ballasted track. We collected the time-to-failure data of S-bonds from the maintenance field of Seoul metro line 2, and made a parametric approach to estimate the statistical distribution that fits the time-to-failure data. The analysis shows that S-bonds have time-to-failure characteristics described by Weibull distribution. The estimated shape parameter of Weibull distribution is 1.1, which means the distribution has constant failure rate characteristics like exponential distribution. The reliability function, hazard function, percentiles and mean lifetime are derived for maintenance support.
Nonlinear Observer Design for PEM Fuel Cell Systems
Kim, Eung-Seok ; Kim, Cheol-Jin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 314~321
In this paper, the robust nonlinear observer will be developed for PEM fuel cell system. Nonlinear model of PEM fuel cell system is introduced to study the design problems of observer. Sliding mode observer is designed to estimate the cathode and anode pressures of PEMFC system. And a nonlinear state observer is also designed to estimate the other states such as supply manifold pressure, Oxygen pressure, Hydrogen pressure, return manifold pressure, etc. The validity of the proposed observer will be verified by using Lyapunov's stability analysis method.
Synthesis of Nanoporous
Materials Using Sol-gel Combustion Method and Its Photovoltaic Characteristics
Heo, Jong-Hyun ; Sung, Youl-Moon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 322~326
In this work, nanoporous
powder was fabricated using Ketjen black, and applied in photovoltaic device based on the Dye-sensitized Solar Cells (DSCs).
powder was fabricated using Ti-isopropoxide and 2-propanol by sol-gel combustion method. For added
variable of Ketjen black, characteristic of porosity, size of particle and crystallite of obtained
nano powder was investigated. The photovoltaic efficiency of the prepared DSCs was measured using
film which prepared on each different heat treatment temperature(
) with paste of
powder. The porosity and size in particle of
powder made with Ketjen black Ig was influenced significantly effect to DSCs characteristic. Heat treatment at
makes the better photovoltaic efficiency which around 6.11%(
, ff=0.63). The sol-gel combustion method was useful to DSCs fabrication.
Synthesis of Nanoprous
Materials for Dye-sensitized Solar Cells Application Using Sol-gel Combustion Method
Han, Chi-Hwan ; Sung, Youl-Moon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 327~331
powder was fabricated using Acetylene black, applied photo voltaic device based on the Dye-sensitized Solar Cells (DSCs) was investigated experimentally.
-powder was fabricated using Ti-isopropoxide and 2-propanol by sol-gel combustion method. For cases of variable Acetylene black, characteristic of porosity, size of particle and crystallite of obtained
nano-powder was investigated. The photovoltaic efficiency of the prepared DSCs was measured using
film which prepared on each different heat treatment temperature(
) with paste of
powder. The porosity and size of particle of
powder made with Acetylene black 0.4g was influenced significantly effect to DSCs characteristic. Heat treatment at
makes the better photovoltaic efficiency which 5.02%(
, ff=0.58). The sol-gel combustion method was useful to DSCs fabrication.
Characteristics of Magnetic Resistance on the YBCO
Lee, Sang-Heon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 332~334
The magnetic properties in YBCO superconducting materials were studied. In the measurement of I-V properties, it was cleared that the mechanism of magnetic properties could not be explained by using conventional flux theory. By changing the density of external magnetic flux, changes in current voltage characteristics in which a superconducting material were also measured. The results showed that the magnetic flux is generated by a vortex current which circulates around the vortex with a sense of rotation opposite to that of the diamagnetic screening surface current. When the external magnetic field was applied to the superconducting magnetometer, some regions of the magnetometer will be destroyed, especially the weak link regions and the defect regions.
A Technique for Removing Adjacent Induction Noise Mixed with Partial Discharge Signals of High Voltage Rotating Machines
Youn, Young-Woo ; Yi, Sang-Hwa ; Hwang, Don-Ha ; Choo, Young-Bae ; Kang, Dong-Sik ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 335~341
Analysis of the partial discharge signal, a technique to diagnose the stator winding insulation is a key function for the diagnosis of high voltage rotating machines and requires high precision. To satisfy this requirement, various denoising techniques such as filtering and differential methods were proposed. However, these techniques can not eliminate a adjacent induction noise that decreases reliability of the diagnosis. A simple novel denoising algorithm, therefore, is proposed for removing the adjacent induction noise in this paper. The algorithm shows good performance in the real partial discharge signals measured by 13kV class capacitive couplers installed at hydro-generator in Dae-cheong Dam.
A Complex Noise Suppression Algorithm for On-line Partial Discharge Diagnosis Systems
Yi, Sang-Hwa ; Youn, Young-Woo ; Choo, Young-Bae ; Kang, Dong-Sik ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 342~348
This paper introduces a novel denoising algorithm for the partial-discharge(PD) signals from power apparatuses. The developed algorithm includes three kinds of specific denoising sub-algorithms. The first sub-algorithm uses the fuzzy logic which classifies the noise types in the magnitude versus phase PD pattern. This sub-algorithm is especially effective in the rejection of the noise with high and constant magnitude. The second one is the method simply removing the pulses in the phase sections below the threshold count in the count versus phase pattern. This method is effective in removing the occasional high level noise pulses. The last denoising sub-algorithm uses the grouping characteristics of PD pulses in the 3D plot of the magnitude versus phase versus cycle. This special technique can remove the periodical noise pulses with varying magnitudes, which are very difficult to be removed by other denoising methods. Each of the sub-algorithm has different characteristic and shows different quality of the noise rejection. On that account, a parameter which numerically expresses the noise possessing degree of signal, is defined and evaluated. Using the parameter and above three sub-algorithms, an adaptive complex noise rejection algorithm for the on-line PD diagnosis system is developed. Proposed algorithm shows good performances in the various real PD signals measured from the power apparatuses in the Korean plants.
Analysis of EMF Mitigation Characteristic for Transmission Tower Using Compact Insulation Arm
Song, Hong-Jun ; Lee, Won-Kyo ; Lee, Sang-Yun ; Choi, In-Hyeok ; Lee, Dong-Il ; Byeon, Ki-Sik ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 349~355
As electrical power demand is gradually increasing, the construction of power transmission facility is unavoidable. However difficulties which resulted from increasing of complaints and NYMBY make power transmission tower to be more environmentally friendly. As an alternative proposal, a new method which is changing conventional iron arm for insulation arm which is made of FRP(Fiber Glass Reinforced Plastics) is in progress. In this paper, we discussed environmentally friendly characteristic of domestic 154 kV testing transmission tower whose insulation arms have same mechanical and excellent electrical properties compare to conventional heavy iron arm.
Healthy Assessment of Generator Stator Cores using EL-CID (ELectromagnetic Core Imperfection Detector)
Kim, Byeong-Rae ; Kim, Hee-Dong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 356~362
The ELectromagnetic Core Imperfection Detector (EL-CID) test was performed on a small generator in the laboratory and a gas turbine generator in the field to assess the fault condition of generator stator core. Artificial defects with six different sizes were introduced in the small generator. The scan results on six defects show a very large increase in the magnitude of fault current compared to that obtained with a healthy core. After the stator core heats up, a thermal imaging camera was used to detect hot spot on the inner surface of the core for comparison. Several faults were found during inspection of the gas turbine generator with the EL-CID. It has been shown that the existence of a fault can be determined by monitoring the magnitude of fault current.
A Design of Low Noise RF Front-End by Improvement Q-factor of On-Chip Spiral Inductor
Ko, Jae-Hyeong ; Jung, Hyo-Bin ; Choi, Jin-Kyu ; Kim, Hyeong-Seok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 363~368
In the paper, we confirmed improvement Noise figure of the entire RF front-end using spiral inductor with PGS(Patterned Ground Shield) and current bleeding techniques. LNA design is to achieve simultaneous noise and input matching. Spiral inductor in input circuit of LNA inserted PGS for betterment of Q-factor. we modeling inductor using EM simulator, so compared with inductor of TSMC 0.18um. We designed and simulation the optimum structure of PGS using Taguchi's method. We confirmed enhancement of noise figure at LNA after substituted for inductor with PGS. Mixer designed using current bleeding techniques for reduced noise. We designed LNA using inductor with PGS and Mixer using current bleeding techniques, so confirmed improvement of noise figure.
The verification of Luminous flux of Reference illuminant for New light source by the calculated correction factor
Hwang, Myung-Keun ; Shin, Sang-Wuk ; Yi, Chin-Woo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 369~372
When measuring the luminous flux of a light source at the integrating sphere photometer, it can know the luminous flux to compare the standard lamp with the specimen lamp at the same location. But in case of PLS(plasma lighting system, microwave discharged lamp), that two lamps are cannot be the same location. If the reference illuminant and specimen lamp are cannot measure identical location, we should measure the variation of the luminous flux. For the outcome we can turn out a correction factor to revise and reflect it. But the better way is calibrate the specimen lamp locate the identical location of reference illuminant measured. In this thesis, we've test to find the correction factor for consider that change the measuring location. And it turns out the correction factor. From this, it presents the result to make a select for the reference illuminant which is against the illuminant type for newly produce.
Optimal Trajectory Generation for Walking Up a Staircase of a Biped Robot Using Genetic Algorithm
Kim, Eun-Su ; Kim, Man-Seak ; Kim, Jong-Wook ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 373~381
In this paper, a humanoid robot is simulated and implemented to walk up a staircase using the blending polynomial and genetic algorithm. Using recently developed kinematics for a biped robot, four schemes for walking up a staircase are newly proposed and simulated separately. For the two schemes of landing a swaying leg on the upper stair, the joint trajectories of seven motors are particularly optimized to generate an energy-minimal motion with the guarantee of walking stability. The proposed scheme of walking upstair is validated by an experiment with a small humanoid robot.
Development of Modular DEAS (mDEAS) and its Application to Optimal Trajectory Generation of Biped Walking
Kim, Eun-Su ; Kim, Jo-Hwan ; Kim, Jong-Wook ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 382~390
This paper newly proposes a modular type dynamic encoding algorithm for searches (DEAS) which partitions the whole parameters into several modules and carries out exhaustive DEAS for each module. uDEAS is used to measure parameter sensitivities to the cost function, and the variables whose sensitivities are similar are grouped to make a module. The proposed optimization method is applied to optimal trajectory generation for biped walking of a humanoid. and the optimization result is compared with those of the former versions of DEAS.
Design of Optimized Fuzzy Cascade Controller Based on HFCGA for Ball & Beam System
Jang, Han-Jong ; Oh, Sung-Kwun ; Kim, Hyun-Ki ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 391~398
In this study, we introduce the design methodology of an optimized fuzzy cascade controller with the aid of hierarchical fair competition-based genetic algorithm(HFCGA) for ball & beam system. The ball & beam system consists of servo motor, beam and ball, and remains mutually connected in line in itself. The ball & beam system determines the position of ball through the control of a servo motor. The displacement change the position of ball leads to the change of the angle of the beam which determines the position angle of a servo motor. Consequently the displacement change of the position of the moving ball and its ensuing change of the angle of the beam results in the change of the position angle of a servo motor. We introduce the fuzzy cascade controller scheme which consists of the outer(1st) controller and the inner(2nd) controller as two cascaded fuzzy controllers, and auto-tune the control parameters(scaling factors) of each fuzzy controller using HFCGA. The inner controller controls the position of lever arm which corresponds to the position angle of a servo motor and the outer controller decides the set-point value of the inner controller. HFCGA is a kind of parallel genetic algorithms(PGAs), and helps alleviate the premature convergence being generated in conventional genetic algorithms (GAs). For a detailed comparative analysis from the viewpoint of the performance results and the design methodology, the proposed method for the ball & beam system which is realized by the fuzzy cascade controller based on HFCGA, is presented in comparison with the conventional PD cascade controller based on serial genetic algorithms.
The Design of Polynomial RBF Neural Network by Means of Fuzzy Inference System and Its Optimization
Baek, Jin-Yeol ; Park, Byaung-Jun ; Oh, Sung-Kwun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 399~406
In this study, Polynomial Radial Basis Function Neural Network(pRBFNN) based on Fuzzy Inference System is designed and its parameters such as learning rate, momentum coefficient, and distributed weight (width of RBF) are optimized by means of Particle Swarm Optimization. The proposed model can be expressed as three functional module that consists of condition part, conclusion part, and inference part in the viewpoint of fuzzy rule formed in 'If-then'. In the condition part of pRBFNN as a fuzzy rule, input space is partitioned by defining kernel functions (RBFs). Here, the structure of kernel functions, namely, RBF is generated from HCM clustering algorithm. We use Gaussian type and Inverse multiquadratic type as a RBF. Besides these types of RBF, Conic RBF is also proposed and used as a kernel function. Also, in order to reflect the characteristic of dataset when partitioning input space, we consider the width of RBF defined by standard deviation of dataset. In the conclusion part, the connection weights of pRBFNN are represented as a polynomial which is the extended structure of the general RBF neural network with constant as a connection weights. Finally, the output of model is decided by the fuzzy inference of the inference part of pRBFNN. In order to evaluate the proposed model, nonlinear function with 2 inputs, waster water dataset and gas furnace time series dataset are used and the results of pRBFNN are compared with some previous models. Approximation as well as generalization abilities are discussed with these results.
Study on the Transmission Delay of Two Priority Classes in One Node in the Foundation Fieldbus
Lee, Yong-Hee ; Hong, Seung-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 407~414
The foundation fieldbus(FF) is one of the fieldbuses most widely used for process control and automation, In order for system designer to optimize medium management, it is imperative to predict transmission delay time of data. In a former research, mathematical modeling to analyze transmission delay of FF token-passing system has been developed based on the assumption that a device node has only one priority data(1Q model), From 1Q model, all of the device nodes, which are connected on the FF system, are defined priority level in advance, and as system operates, data are generated based on given priority level. However, in practice, some non-periodic data can have different priority levels from one device. Therefore, new mathematical model is necessary for the case where different priority levels of data are created under one device node(2Q model). In this research, the mathematical model for 2Q model is developed using the equivalent queue model. Furthermore, the characteristics of transmission delay of 2Q model which is presented in this paper were compared with 1Q model. The validity of the analytical model was verified by using a simulation experiment.
Comparisons of Error Characteristics between TOA and TDOA Positioning in Dense Multipath Environment
Park, Ji-Won ; Park, Ji-Hee ; Song, Seung-Hun ; Sung, Tae-Kyung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 415~421
TOA(time-of-arrival) and TDOA(time-difference-of-arrival) positioning techniques are commonly used in many radio-navigation systems. From the literature, it is known that the position estimate and error covariance matrix of TDOA obtained by GN(Gauss-Newton) method is exactly the same as that of TOA when the error source of the range measurement is only an IID white Gaussian noise. In case of geo-location and indoor positioning, however, multi-path or NLOS(non-line-of-sight) error is frequently appeared in range measurements. Though its occurrence is random, the multipath acts like a bias for a stationary user if it occurs. This paper presents the comparisons of error characteristics between TOA and TDOA positioning in presence of multi-path or NLOS error. It is analytically shown that the position estimate of TDOA is exactly the same as that of TOA even when bias errors are included in range measurements with different magnitudes. By computer simulation, position estimation error and error distribution are analyzed in presence of range bias errors.
Study on the Development of Meridian Impedance Measurement System
Lee, Woo-Cheol ; Yin, Chang-Shik ; Min, Kyoung-Kee ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 2, 2009, Pages 422~429
Meridian which used as the basic theory of acupuncture treatment, is an important functional connection system of acupuncture point in oriental medicine. Yangdorak and EAV have lack of precision because of using 2-electrode method, occurring high non-uniformed current density and electrode contact status on electrode placement spot. Therefore we implemented a meridian impedance measurement system for measuring meridian impedance using 4-electrode method. In order to confirm the precision of developed system, we made an constant current characteristic experiment using standard resistor. As a results of clinical study with 18 subjects, the meridian impedance showed that reproductivity and repeatability of HT7 acupuncture point are
standard deviation) and
, respectively. And reproductivity and repeatability of PC7 are
respectively. The proposed system was stable and reliable. Therefore this study proved AC impedance method to valid in measuring meridian impedance, and also verified precision and repeatability of the proposed meridian impedance measurement system. The proposed system will serve as more effective method of measuring meridian phenomena as a bioelectric signal in clinical practice.