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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Electrical Engineering and Technology
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The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 6, Issue 6 - Nov 2011
Volume 6, Issue 5 - Sep 2011
Volume 6, Issue 4 - Jul 2011
Volume 6, Issue 3 - May 2011
Volume 6, Issue 2 - Mar 2011
Volume 6, Issue 1 - Jan 2011
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Type-2 Fuzzy Logic Optimum PV/inverter Sizing Ratio for Grid-connected PV Systems: Application to Selected Algerian Locations
Makhloufi, S. ; Abdessemed, R. ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 731~741
DOI : 10.5370/JEET.2011.6.6.731
Conventional methodologies (empirical, analytical, numerical, hybrid, etc.) for sizing photovoltaic (PV) systems cannot be used when the relevant meteorological data are not available. To overcome this situation, modern methods based on artificial intelligence techniques have been developed for sizing the PV systems. In the present study, the optimum PV/inverter sizing ratio for grid-connected PV systems with orientation due south and inclination angles of
in selected Algerian locations was determined in terms of total system output using type-2 fuzzy logic. Because measured data for the locations chosen were not available, a year of synthetic hourly meteorological data for each location generated by the PVSYST software was used in the simulation.
A Novel Algorithm for Fault Type Fast Diagnosis in Overhead Transmission Lines Using Hidden Markov Models
Jannati, M. ; Jazebi, S. ; Vahidi, B. ; Hosseinian, S.H. ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 742~749
DOI : 10.5370/JEET.2011.6.6.742
Power transmission lines are one of the most important components of electric power system. Failures in the operation of power transmission lines can result in serious power system problems. Hence, fault diagnosis (transient or permanent) in power transmission lines is very important to ensure the reliable operation of the power system. A hidden Markov model (HMM), a powerful pattern recognizer, classifies events in a probabilistic manner based on fault signal waveform and characteristics. This paper presents application of HMM to classify faults in overhead power transmission lines. The algorithm uses voltage samples of one-fourth cycle from the inception of the fault. The simulation performed in EMTPWorks and MATLAB environments validates the fast response of the classifier, which provides fast and accurate protection scheme for power transmission lines.
Controller Optimization for Bidirectional Power Flow in Medium-Voltage DC Power Systems
Chung, Il-Yop ; Liu, Wenxin ; Cartes, David A. ; Cho, Soo-Hwan ; Kang, Hyun-Koo ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 750~759
DOI : 10.5370/JEET.2011.6.6.750
This paper focuses on the control of bidirectional power flow in the electric shipboard power systems, especially in the Medium-Voltage Direct Current (MVDC) shipboard power system. Bidirectional power control between the main MVDC bus and the local zones can improve the energy efficiency and control flexibility of electric ship systems. However, since the MVDC system contains various nonlinear loads such as pulsed power load and radar in various subsystems, the voltage of the MVDC and the local zones varies significantly. This voltage variation affects the control performance of the bidirectional DC-DC converters as exogenous disturbances. To improve the control performance regardless of uncertainties and disturbances, this paper proposes a novel controller design method of the bidirectional DC-DC converters using
control theory and intelligent optimization algorithm. The performance of the proposed method is verified via large-scale real-time digital simulation of a notional shipboard MVDC power system.
A Metamodeling Approach for Leader Progression Model-based Shielding Failure Rate Calculation of Transmission Lines Using Artificial Neural Networks
Tavakoli, Mohammad Reza Bank ; Vahidi, Behrooz ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 760~768
DOI : 10.5370/JEET.2011.6.6.760
The performance of transmission lines and its shielding design during a lightning phenomenon are quite essential in the maintenance of a reliable power supply to consumers. The leader progression model, as an advanced approach, has been recently developed to calculate the shielding failure rate (SFR) of transmission lines using geometrical data and physical behavior of upward and downward lightning leaders. However, such method is quite time consuming. In the present paper, an effective method that utilizes artificial neural networks (ANNs) to create a metamodel for calculating the SFR of a transmission line based on shielding angle and height is introduced. The results of investigations on a real case study reveal that, through proper selection of an ANN structure and good training, the ANN prediction is very close to the result of the detailed simulation, whereas the Processing time is by far lower than that of the detailed model.
Voltage Quality Improvement with Neural Network-Based Interline Dynamic Voltage Restorer
Aali, Seyedreza ; Nazarpour, Daryoush ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 769~775
DOI : 10.5370/JEET.2011.6.6.769
Custom power devices such as dynamic voltage restorer (DVR) and DSTATCOM are used to improve the power quality in distribution systems. These devices require real power to compensate the deep voltage sag during sufficient time. An interline DVR (IDVR) consists of several DVRs in different feeders. In this paper, a neural network is proposed to control the IDVR performance to achieve optimal mitigation of voltage sags, swell, and unbalance, as well as improvement of dynamic performance. Three multilayer perceptron neural networks are used to identify and regulate the dynamics of the voltage on sensitive load. A backpropagation algorithm trains this type of network. The proposed controller provides optimal mitigation of voltage dynamic. Simulation is carried out by MATLAB/Simulink, demonstrating that the proposed controller has fast response with lower total harmonic distortion.
Wide-area Frequency-based Tripped Generator Locating Method for Interconnected Power Systems
Kook, Kyung-Soo ; Liu, Yilu ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 776~785
DOI : 10.5370/JEET.2011.6.6.776
Since the Internet-based real-time Global Positioning System(GPS) synchronized widearea power system frequency monitoring network (FNET) was proposed in 2001, it has been monitoring the power system frequency in interconnected United States power systems and numerous interesting behaviors have been observed, including frequency excursion propagation. We address the consistency of a frequency excursion detection order of frequency disturbance recorders in FNET in relation to the same generation trip, as well as the ability to recreate by power systems dynamic simulation. We also propose a new method, as an application of FNET measurement, to locate a tripped generator using power systems dynamic simulation and wide-area frequency measurement. The simulation database of all the possible trips of generators in the interconnected power systems is created using the off-line power systems dynamic simulation. When FNET detects a sudden drop in the monitoring frequency, which is most likely due to a generation trip in power systems, the proposed algorithm locates a tripped generator by finding the best matching case of the measured frequency excursion in the simulation database in terms of the frequency drop detection order and the time of monitoring points.
Optimal Capacitor Placement Considering Voltage-stability Margin with Hybrid Particle Swarm Optimization
Kim, Tae-Gyun ; Lee, Byong-Jun ; Song, Hwa-Chang ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 786~792
DOI : 10.5370/JEET.2011.6.6.786
The present paper presents an optimal capacitor placement (OCP) algorithm for voltagestability enhancement. The OCP issue is represented using a mixed-integer problem and a highly nonlinear problem. The hybrid particle swarm optimization (HPSO) algorithm is proposed to solve the OCP problem. The HPSO algorithm combines the optimal power flow (OPF) with the primal-dual interior-point method (PDIPM) and ordinary PSO. It takes advantage of the global search ability of PSO and the very fast simulation running time of the OPF algorithm with PDIPM. In addition, OPF gives intelligence to PSO through the information provided by the dual variable of the OPF. Numerical results illustrate that the HPSO algorithm can improve the accuracy and reduce the simulation running time. Test results evaluated with the three-bus, New England 39-bus, and Korea Electric Power Corporation systems show the applicability of the proposed algorithm.
Phase Current Magnitude Variation Method to Reduce End-Effect Force of PM Linear Synchronous Motor
Kim, Min-Jae ; Lim, Jae-Won ; Yim, Woo-Gyong ; Jung, Hyun-Kyo ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 793~798
DOI : 10.5370/JEET.2011.6.6.793
Numerous methods are available for reducing the end-effect force of linear machines. Majority of these methods focus on redesigning the poles or slots. However, these methods require additional manufacturing cost and decrease the power density. The current paper introduces another approach to reduce the end-effect force. The new approach is a method of tuning the input phase current magnitudes individually. According to the proposed method, reduction of the end-effect force could be achieved without redesigning the poles/slots or attaching auxiliary poles/slots. The proposed method is especially applicable when the target motor is very expensive or will be used for a special mission, such as hauling army vehicles equipped with three single-phase inverters. The validity of the suggested method was exemplified by the finite element method with three-phase permanent-magnet linear synchronous motor.
Comparison of Three Modeling Methods for Identifying Unknown Magnetization of Ferromagnetic Thin Plate
Choi, Nak-Sun ; Kim, Dong-Wook ; Yang, Chang-Seob ; Chung, Hyun-Ju ; Kim, Hong-Joon ; Kim, Dong-Hun ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 799~805
DOI : 10.5370/JEET.2011.6.6.799
This study presents three different magnetization models for identifying unknown magnetization of the ferromagnetic thin plate of a ship. First, the forward problem should be solved to accurately predict outboard magnetic fields due to the magnetization distribution estimated at a certain time. To achieve this, three different modeling methods for representing remanent magnetization (i.e., magnetic charge method, magnetic dipole array method, and magnetic moment method) were utilized. Material sensitivity formulas containing the first-order gradient information of an objective function were then adopted for an efficient search of an optimum magnetization distribution on the hull. The validity of the proposed methods was tested with a scale model ship, and field signals predicted from the three different models were thoroughly investigated with reference to the experimental data.
A Study on Swarm Robot-Based Invader-Enclosing Technique on Multiple Distributed Object Environments
Ko, Kwang-Eun ; Park, Seung-Min ; Park, Jun-Heong ; Sim, Kwee-Bo ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 806~816
DOI : 10.5370/JEET.2011.6.6.806
Interest about social security has recently increased in favor of safety for infrastructure. In addition, advances in computer vision and pattern recognition research are leading to video-based surveillance systems with improved scene analysis capabilities. However, such video surveillance systems, which are controlled by human operators, cannot actively cope with dynamic and anomalous events, such as having an invader in the corporate, commercial, or public sectors. For this reason, intelligent surveillance systems are increasingly needed to provide active social security services. In this study, we propose a core technique for intelligent surveillance system that is based on swarm robot technology. We present techniques for invader enclosing using swarm robots based on multiple distributed object environment. The proposed methods are composed of three main stages: location estimation of the object, specified object tracking, and decision of the cooperative behavior of the swarm robots. By using particle filter, object tracking and location estimation procedures are performed and a specified enclosing point for the swarm robots is located on the interactive positions in their coordinate system. Furthermore, the cooperative behaviors of the swarm robots are determined via the result of path navigation based on the combination of potential field and wall-following methods. The results of each stage are combined into the swarm robot-based invader-enclosing technique on multiple distributed object environments. Finally, several simulation results are provided to further discuss and verify the accuracy and effectiveness of the proposed techniques.
Design of UHF CMOS Front-ends for Near-field Communications
Hamedi-Hagh, Sotoudeh ; Tabesh, Maryam ; Oh, Soo-Seok ; Park, Noh-Joon ; Park, Dae-Hee ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 817~823
DOI : 10.5370/JEET.2011.6.6.817
This paper introduces an efficient voltage multiplier circuit for improved voltage gain and power efficiency of radio frequency identification (RFID) tags. The multiplier is fully integratable and takes advantage of both passive and active circuits to reduce the required input power while yielding the desired DC voltage. A six-stage voltage multiplier and an ultralow power voltage regulator are designed in a 0.13
complementary metal-oxide semiconductor process for 2.45 GHz RFID applications. The minimum required input power for a 1.2 V supply voltage in the case of a 50
antenna is -20.45 dBm. The efficiency is 15.95% for a 1
load. The regulator consumes 129 nW DC power and maintains the reference voltage in a 1.1% range with
varying from 0.8 to 2 V. The power supply noise rejection of the regulator is 42 dB near a 2.45 GHz frequency and performs better than -32 dB from 100 Hz to 10 GHz frequencies.
Transmission Line Analysis of Accumulation Layer in IEGT
Moon, Jin-Woo ; Chung, Sang-Koo ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 824~828
DOI : 10.5370/JEET.2011.6.6.824
Transmission line analysis of the surface a cumulation layer in injection-enhanced gate transistor (IEGT) is presented for the first time, based on per-unit-length resistance and conductance of the surface layer beneath the gate of IEGT. Lateral electric field on the accumulation layer surface, as well as the electron current injected into the accumulation layer, is governed by the well-known wave equation, and decreases as an exponential function of the lateral distance from the cathode. Unit-length resistance and conductance of the layer are expressed in terms of the device parameters and the applied gate voltage. Results obtained from the experiments are consistent with the numerical simulations.
Power Frequency Magnetic Field Reduction Method for Residents in the Vicinity of Overhead Transmission Lines Using Passive Loop
Lee, Byeong-Yoon ; Myung, Sung-Ho ; Cho, Yeun-Gyu ; Lee, Dong-Il ; Lim, Yun-Seog ; Lee, Sang-Yun ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 829~835
DOI : 10.5370/JEET.2011.6.6.829
A power frequency magnetic field reduction method using passive loop is presented. This method can be used to reduce magnetic fields generated within the restricted area near transmission lines by alternating current overhead transmission lines. A reduction algorithm is described and related equations for magnetic field reduction are explained. The proposed power frequency magnetic field reduction method is applied to a scaled-down transmission line model. The lateral distribution of reduction ratio between magnetic fields before and after passive loop installation is calculated to evaluate magnetic field reduction effects. Calculated results show that the passive loop can be used to cost-effectively reduce power frequency magnetic fields in the vicinity of transmission lines generated by overhead transmission lines, compared with other reduction methods, such as active loop, increase in transmission line height, and power transmission using underground cables.
Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films as Gate Dielectric for Organic Thin Film Transistor
Ao, Wei ; Lim, Jae-Sung ; Shin, Paik-Kyun ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 836~841
DOI : 10.5370/JEET.2011.6.6.836
Plasma polymerized methyl methacrylate (ppMMA) thin films were deposited by plasma polymerization technique with different plasma powers and subsequently thermally treated at temperatures of 60 to
. To find a better ppMMA preparation technique for application to organic thin film transistor (OTFT) as dielectric layer, the chemical composition, surface morphology, and electrical properties of ppMMA were investigated. The effect of ppMMA thin-film preparation conditions on the resulting thin film properties were discussed, specifically O-H site content in the pMMA, dielectric constant, leakage current density, and hysteresis.
A New CW CO
Laser with Precise Output and Minimal Fluctuation by Adopting a High-frequency LCC Resonant Converter
Lee, Dong-Gil ; Park, Seong-Wook ; Yang, Yong-Su ; Kim, Hee-Je ; Xu, Guo-Cheng ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 842~848
DOI : 10.5370/JEET.2011.6.6.842
The current study proposes the design of a hybrid series-parallel resonant converter (SPRC) and a three-stage Cockcroft-Walton voltage multiplier for precisely adjusting the power generated by a continuous wave (CW)
laser. The design of a hybrid SPRC, called LCC resonant converter, is described, and the fundamental approximation of a high-voltage and high-frequency (HVHF) transformer with a resonant tank is discussed. The results of the current study show that the voltage drop and ripple of a three-stage Cockcroft-Walton voltage multiplier depend on frequency. The power generated by a CW
laser can be precisely adjusted by a variable-frequency controller using a DSP (TMS320F2812) microprocessor. The proposed LCC converter could be used to obtain a maximum laser output power of 23 W. Moreover, it could precisely adjust the laser output power within 4.3 to 23 W at an operating frequency range of 187.5 to 370 kHz. The maximum efficiency of the
laser system is approximately 16.5%, and the minimum ripple of output voltage is about 1.62%.
Study on the Mitigation of the Resonance due to the Power-Bus Structure using Periodic Metal-Strip Loaded Sheets
Kahng, Sung-Tek ; Kim, Hyeong-Seok ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 849~852
DOI : 10.5370/JEET.2011.6.6.849
This paper investigates a method to tackle the resonance problems of the rectangular power-bus structure(PBS) using thin sheets loaded with periodic metal strips. The equivalent surface impedance of the proposed loading is calculated and involved in the expression of the impedance that accounts for in the PBS, in order to improve the resonance behavior of the original structure. The effects of the strips and the immediate surroundings are illustrated by a number of numerical experiments. Also the restrictions of the technique are addressed.
Identification of Fuzzy Inference Systems Using a Multi-objective Space Search Algorithm and Information Granulation
Huang, Wei ; Oh, Sung-Kwun ; Ding, Lixin ; Kim, Hyun-Ki ; Joo, Su-Chong ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 853~866
DOI : 10.5370/JEET.2011.6.6.853
We propose a multi-objective space search algorithm (MSSA) and introduce the identification of fuzzy inference systems based on the MSSA and information granulation (IG). The MSSA is a multi-objective optimization algorithm whose search method is associated with the analysis of the solution space. The multi-objective mechanism of MSSA is realized using a non-dominated sorting-based multi-objective strategy. In the identification of the fuzzy inference system, the MSSA is exploited to carry out parametric optimization of the fuzzy model and to achieve its structural optimization. The granulation of information is attained using the C-Means clustering algorithm. The overall optimization of fuzzy inference systems comes in the form of two identification mechanisms: structure identification (such as the number of input variables to be used, a specific subset of input variables, the number of membership functions, and the polynomial type) and parameter identification (viz. the apexes of membership function). The structure identification is developed by the MSSA and C-Means, whereas the parameter identification is realized via the MSSA and least squares method. The evaluation of the performance of the proposed model was conducted using three representative numerical examples such as gas furnace, NOx emission process data, and Mackey-Glass time series. The proposed model was also compared with the quality of some "conventional" fuzzy models encountered in the literature.
Reducing the Search Space for Pathfinding in Navigation Meshes by Using Visibility Tests
Kim, Hyun-Gil ; Yu, Kyeon-Ah ; Kim, Jun-Tae ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 867~873
DOI : 10.5370/JEET.2011.6.6.867
A navigation mesh (NavMesh) is a suitable tool for the representation of a three-dimensional game world. A NavMesh consists of convex polygons covering free space, so the path can be found reliably without detecting collision with obstacles. The main disadvantage of a NavMesh is the huge state space. When the
algorithm is applied to polygonal meshes for detailed terrain representation, the pathfinding can be inefficient due to the many states to be searched. In this paper, we propose a method to reduce the number of states searched by using visibility tests to achieve fast searching even on a detailed terrain with a large number of polygons. Our algorithm finds the visible vertices of the obstacles from the critical states and uses the heuristic function of
, defined as the distance to the goal through such visible vertices. The results show that the number of searched states can be substantially reduced compared to the
search with a straight-line distance heuristic.
Decoupling Controller Design for H
Park, Tae-Dong ; Choi, Goon-Ho ; Cho, Yong-Seok ; Park, Ki-Heon ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 874~882
DOI : 10.5370/JEET.2011.6.6.874
The decoupling design for the one-degree-of-freedom controller system is treated within the
framework. In the present study, we demonstrate that the
performance problem in the decoupling design is reduced into interpolation problems on scalar functions. To guarantee the properness of decoupling controllers and the overall transfer matrix, the relative degree conditions on the interpolating scalar functions are derived. To find the interpolating functions with relative degree constraints, Nevanlinna-Pick algorithm with starting function constraint is utilized in the present study. An illustrative example is given to provide details regarding the solution.
Adaptive Parameter Estimation Method for Wireless Localization Using RSSI Measurements
Cho, Hyun-Hun ; Lee, Rak-Hee ; Park, Joon-Goo ;
Journal of Electrical Engineering and Technology, volume 6, issue 6, 2011, Pages 883~887
DOI : 10.5370/JEET.2011.6.6.883
Location-based service (LBS) is becoming an important part of the information technology (IT) business. Localization is a core technology for LBS because LBS is based on the position of each device or user. In case of outdoor, GPS - which is used to determine the position of a moving user - is the dominant technology. As satellite signal cannot reach indoor, GPS cannot be used in indoor environment. Therefore, research and study about indoor localization technology, which has the same accuracy as an outdoor GPS, is needed for "seamless LBS". For indoor localization, we consider the IEEE802.11 WLAN environment. Generally, received signal strength indicator (RSSI) is used to obtain a specific position of the user under the WLAN environment. RSSI has a characteristic that is decreased over distance. To use RSSI at indoor localization, a mathematical model of RSSI, which reflects its characteristic, is used. However, this RSSI of the mathematical model is different from a real RSSI, which, in reality, has a sensitive parameter that is much affected by the propagation environment. This difference causes the occurrence of localization error. Thus, it is necessary to set a proper RSSI model in order to obtain an accurate localization result. We propose a method in which the parameters of the propagation environment are determined using only RSSI measurements obtained during localization.