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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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Journal DOI :
The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 7, Issue 6 - Nov 2012
Volume 7, Issue 5 - Sep 2012
Volume 7, Issue 4 - Jul 2012
Volume 7, Issue 3 - May 2012
Volume 7, Issue 2 - Mar 2012
Volume 7, Issue 1 - Jan 2012
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Model of Information Exchange for Decentralized Congestion Management
Song, Sung-Hwan ; Jeong, Jae-Woo ; Yoon, Yong-Tae ; Moon, Seung-Il ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 141~150
DOI : 10.5370/JEET.2012.7.2.141
The present study examines an efficient congestion management system compatible with the evolving environment. The key is to build an information model shared and exchanged for marketbased solutions to alleviate congestion. Traditional methods for congestion management can be classified into two categories, i.e., the centralized scheme and the decentralized scheme, depending on the extent to which the independent system operator (ISO) is involved in market participants' (MPs) activities. Although the centralized scheme is more appropriate for providing reliable system operation and relieving congestion in near real-time, the decentralized scheme is preferred for supporting efficient market operation. The minimum set of information between the ISO and MPs for decentralized scheme is identified: i) congestion-based zone, ii) Power Transfer Distribution Factors, and iii) transmission congestion cost. The mathematical modeling of the proposed information is expressed, considering its process of making effective use of information. Numerical analysis is conducted to demonstrate both cost minimization from the MP perspective and the reliability enhancement from the ISO perspective based on the proposed information exchange scheme.
Zero-one Integer Programming Approach to Determine the Minimum Break Point Set in Multi-loop and Parallel Networks
Moirangthem, Joymala ; Dash, Subhransu Sekhar ; Ramaswami, Ramas ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 151~156
DOI : 10.5370/JEET.2012.7.2.151
The current study presents a zero-one integer programming approach to determine the minimum break point set for the coordination of directional relays. First, the network is reduced if there are any parallel lines or three-end nodes. Second, all the directed loops are enumerated to reduce the iteration. Finally, the problem is formulated as a set-covering problem, and the break point set is determined using the zero-one integer programming technique. Arbitrary starting relay locations and the arbitrary consideration of relay sequence to set and coordinate relays result in navigating the loops many times and futile attempts to achieve system-wide relay coordination. These algorithms are compared with the existing methods, and the results are presented. The problem is formulated as a setcovering problem solved by the zero-one integer programming approach using LINGO 12, an optimization modeling software.
Economic Considerations Underlying the Adoption of HVDC and HVAC for the Connection of an Offshore Wind Farm in Korea
Hur, Don ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 157~162
DOI : 10.5370/JEET.2012.7.2.157
Wind energy is created in mega-sized wind farms situated kilometers off shore. In fact, two possibilities are considered for the transmission system between the offshore wind farm and the onshore grid: high-voltage direct current and high-voltage alternating current. From this point of view, the current paper aims to compare both systems for a 2 GW wind farm situated 80 km from the Point of Common Coupling on an economic basis using a discounted cash flow analysis. A tool is developed in Microsoft Excel to allow for quick insight in the variation of input parameters.
Parameter Estimation Method of Low-Frequency Oscillating Signals Using Discrete Fourier Transforms
Choi, Joon-Ho ; Shim, Kwan-Shik ; Nam, Hae-Kon ; Lim, Young-Chul ; Nam, Soon-Ryul ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 163~170
DOI : 10.5370/JEET.2012.7.2.163
This paper presents a DFT (Discrete Fourier Transform) based estimation algorithm for the parameters of a low-frequency oscillating signal. The proposed method estimates the parameters, i.e., the frequency, the damping factor, the mode amplitude, and the phase, by fitting a discrete Fourier spectrum with an exponentially damped cosine function. Parameter estimation algorithms that consider the spectrum leakage of the discrete Fourier spectrum are introduced. The multi-domain mode test functions are tested in order to verify the accuracy and efficiency of the proposed method. The results show that the proposed algorithms are highly applicable to the practical computation of low-frequency parameter estimations based on DFTs.
The System Design and Demonstration for Autonomous Microgrid Operation
Jyung, Tae-Young ; Jeong, Ki-Seok ; Baek, Young-Sik ; Kim, Heung-Geun ; Seo, Gyu-Seok ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 171~177
DOI : 10.5370/JEET.2012.7.2.171
The autonomous microgrid is a system that is autonomously operated depending on the grid and internal load condition, without the operator's intervention. In this study, a control algorithm for the microsource and an operation algorithm for the microgrid are proposed to realize the autonomous microgrid system. In addition, a microgrid operation system based on the operation algorithm is proposed. The electromagnetic transient program is used by the proposed microsource control algorithm for simulation, and the validity of the algorithm is verified. The proposed operation system is verified based on a case study using a simulator and test devices.
Quench Protection System for the KSTAR Toroidal Field Superconducting Coil
Lee, Dong-Keun ; Choi, Jae-Hoon ; Jin, Jong-Kook ; Hahn, Sang-Hee ; Kim, Yaung-Soo ; Ahn, Hyun-Sik ; Jang, Gye-Yong ; Yun, Min-Seong ; Seong, Dae-Kyoung ; Shin, Hyun-Seok ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 178~183
DOI : 10.5370/JEET.2012.7.2.178
The design of the integrated quench protection (QP) system for the high current superconducting magnet (SCM) has been fabricated and tested for the toroidal field (TF) coil system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The QP system is capable of protecting the TF SCM, which consists of 16 identical coils serially connected with a stored energy of 495 MJ at the design operation level at 35.2 kA per turn. Given that the power supply for the TF coils can only ramp up and maintain the coil current, the design of the QP system includes two features. The first is a basic fast discharge function to protect the TF SCM by a dump resistor circuit with a 7 s time constant in case of coil quench event. The second is a slow discharge function with a time constant of 360 s for a daily TF discharge or for a stop demand from the tokamak control system. The QP system has been successfully tested up to 40 kA with a short circuit and up to 34 kA with TF SCM in the second campaign of KSTAR. This paper describes the characteristics of the TF QP systems and test results of the plasma experiment of KSTAR in 2009.
Unbalanced Magnetic Forces in Rotational Unsymmetrical Transverse Flux Machine
Baserrah, Salwa ; Rixen, Keno ; Orlik, Bernd ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 184~192
DOI : 10.5370/JEET.2012.7.2.184
The torque and unbalanced magnetic forces in permanent magnet machines are resultants of the tangential, axial and normal magnetic forces, respectively. Those are in general influenced by pole-teeth-winding configuration. A study of the torque and unbalanced magnetic forces of a small flux concentrating permanent magnet transverse flux machine (FCPM-TFM) in segmented compact structure is presented in this paper. By using FLUX3D software from Cedrat, Maxwell stress tensor has been solved. Finite element (FE-) magneto static study followed by transient analysis has been conducted to investigate the influence of unsymmetrical winding pattern, in respect to the rotor, on the performance of the FCPM-TFM. Calculating the magnetic field components in the air gap has required an introduction of a 2D grid in the middle of the air gap, whereby good estimations of the forces are obtained. In this machine, the axial magnetic forces reveal relatively higher amplitudes compared to the normal forces. Practical results of a prototype motor are demonstrated through the analysis.
Comparative Study on the Optimization Methods for a Motor Drive of Artificial Hearts
Pohlmann, Andre ; LeBmann, Marc ; Hameyer, Kay ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 193~199
DOI : 10.5370/JEET.2012.7.2.193
Worldwide cardiovascular diseases are the major cause of death. Aside from heart transplants, which are limited due to the availability of human donor hearts, artificial hearts are the only therapy available for terminal heart diseases. For various reasons, a total implantable artificial heart is desirable. But the limited space in the human thorax sets rigorous restrictions on the weight and dimensions of the device. Nevertheless, the appropriate functionality of the artificial heart must be ensured and blood damage must be prevented. These requirements set further restrictions to the drive of this device. In the this paper, two optimization methods, namely, the manual parameter variation and Differential Evolution algorithm, are presented and applied to match the specifications of an artificial heart.
Performance Analysis of the Linear Induction Motor for the Deep-Underground High-Speed GTX
Park, Chan-Bae ; Lee, Hyung-Woo ; Lee, Ju ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 200~206
DOI : 10.5370/JEET.2012.7.2.200
In order to develop a deep-underground great train express (GTX) in South Korea, the specifications decision and development of a traction control system (including an inverter and a traction motor), which considers a variety of route conditions, must be advanced. In this study, we examined the running resistance properties of a high-speed traction system based on a variety of tunnel types and vehicle organization methods. Then, we studied the power requirements necessary for the traction motor to maintain balanced speed in the high-speed traction system. From this, we determined the design criteria for the development of a high-speed traction system for use in the deep-underground GTX. Finally, we designed a linear induction motor (LIM) for a propulsion system, and we used the finite element method (FEM) to analyze its performance as it travelled through deep-underground tunnels.
Preparation and Characteristics of Li
Anode Material for Hybrid Supercapacitor
Lee, Byung-Gwan ; Yoon, Jung-Rag ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 207~211
DOI : 10.5370/JEET.2012.7.2.207
was successfully synthesized by a solid-phase method at 800, 850, and
according to the
cubic spinel phase structure. To achieve higher EDLC energy density with the
, the negative electrode of the hybrid supercapacitor was studied in this work. The electrochemical performances of the hybrid supercapacitor and EDLC were characterized by constant current discharge curves, c-rate, and cycle performance testing. The capacitance (1st cycle) of the hybrid supercapacitor and EDLC was 209 and 109 F, respectively, which is higher than EDLC. The capacitance of the hybrid supercapacitor decreases from 209 F to 101 F after 20 cycles when discharged at several specific current densities ranging from 1 to 10 A. In contrast, capacitance of the EDLC hardly decreases after 20 cycles. Results show that hybrid supercapacitor benefits from the high rate capability of supercapacitor and high capacity of the battery. Findings also prove that the hybrid supercapacitor is an energy storage device where the supercapacitor and the Li ion secondary battery coexist in one cell system.
Optimization Shape of Variable-Capacitance Micromotor Using Seeker Optimization Algorithm
Ketabi, Abbas ; Navardi, Mohammad Javad ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 212~220
DOI : 10.5370/JEET.2012.7.2.212
In the current paper, the optimization shape of a polysilicon variable-capacitance micromotor (VCM) was determined using the seeker optimization algorithm (SOA). The optimum goal of the algorithm was to find the maximum torque value and minimum ripple torque by varying the geometrical parameters. The optimization process was performed using a combination of SOA and the finite-element method (FEM). The fitness value was calculated via FEM analysis using COMSOL3.4, and SOA was realized by MATLAB7.4. The proposed method was applied to a VCM with eight and six poles at the stator and rotor, respectively. For comparison, this optimization was also performed using the genetic algorithm. The results show that the optimized micromotor using SOA had a higher torque value and lower torque ripple, indicating the validity of this methodology for VCM design.
Design of Current-Type Readout Integrated Circuit for 160 × 120 Pixel Array Applications
Jung, Eun-Sik ; Bae, Young-Seok ; Sung, Man-Young ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 221~224
DOI : 10.5370/JEET.2012.7.2.221
We propose a Readout Integrated Circuit (ROIC), which applies a fixed current bias sensing method to the input stage in order to simplify the circuit structure and the infrared sensor characteristic control. For the sample-and-hold stage to display and control a signal detected by the infrared sensor using a two-dimensional (2D) focal plane array, a differential delta sampling (DDS) circuit is proposed, which effectively removes the FPN. In addition, the output characteristic is improved to have wider bandwidth and higher gain by applying a two-stage variable gain amplifier (VGA). The output characteristic of the proposed device was 23.91 mV/
, and the linearity error rate was less than 0.22%. After checking the performance of the ROIC using HSPICE simulation, the chip was manufactured and measured using the SMIC 0.35 um standard CMOS process to confirm that the simulation results from the actual design are in good agreement with the measurement results.
A Simulator for Potential Distribution Analysis
Kil, Gyung-Suk ; Gil, Hyong-Jun ; Park, Dae-Won ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 225~229
DOI : 10.5370/JEET.2012.7.2.225
This paper proposes a reduced-scale simulator that can replace numerical analytic methods for the estimation of potential distribution caused by ground faults in various grounding systems. The simulator consists of a hemispherical electrolytic tank, a three-dimensional potential probe, a grounding electrode, and a data acquisition module. The potential distribution is measured using a potentiometer with a position-tracing function when a test current flows to the grounding electrode. Using the simulator, we could clearly analyze the potential distribution for a reduced- scale model by one-eightieth of the buried depth and length of the grounding rod and grounding grid. Once both the shape of the grounding electrode and the fault current are known, the actual potential distribution can be estimated.
Analysis of Leak and Water Absorption Test Results for Water-Cooled Generator Stator Windings
Kim, Hee-Soo ; Bae, Yong-Chae ; Lee, Wook-Ryun ; Lee, Doo-Young ; Kim, Hee-Dong ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 230~235
DOI : 10.5370/JEET.2012.7.2.230
Cases of insulation breakdown damage of water-cooled generator stator windings occur frequently due to coolant leakage and water absorption worldwide. Such serious accidents may cause not only enormous economic loss but also very serious grid accidents in terms of stable supply of electric power. More than 50 % of domestic generators have been operated for more than 15 years, and leak and water absorption problem of windings are often found during the planned preventive maintenance period. Since 2005, leak and water absorption tests have been performed for total watercooled stator windings after fully drying the inside of the windings. The results are then comprehensively analyzed. The result of the test performed by GE, a foreign manufacturer, for 141 generators showed failures in 80 of them (failure rate: 57 %), whereas in the tests carried out in Korean domestic power plants, only 14 out of 50 generators showed failures (failure rate: 28 %).
Impact of Interface Charges on the Transient Characteristics of 4H-SiC DMOSFETs
Kang, Min-Seok ; Bahng, Wook ; Kim, Nam-Kyun ; Ha, Jae-Geun ; Koh, Jung-Hyuk ; Koo, Sang-Mo ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 236~239
DOI : 10.5370/JEET.2012.7.2.236
In this paper, we study the transient characteristics of 4H-SiC DMOSFETs with different interface charges to improve the turn-on rising time. A physics-based two-dimensional mixed device and circuit simulator was used to understand the relationship between the switching characteristics and the physical device structures. As the
/SiC interface charge increases, the current density is reduced and the switching time is increased, which is due primarily to the lowered channel mobility. The result of the switching performance is shown as a function of the gate-to-source capacitance and the channel resistance. The results show that the switching performance of the 4H-SiC DMOSFET is sensitive to the channel resistance that is affected by the interface charge variations, which suggests that it is essential to reduce the interface charge densities in order to improve the switching speed in 4H-SiC DMOSFETs.
An Intelligent Multi-multivariable Dynamic Matrix Control Scheme for a 160 MW Drum-type Boiler-Turbine System
Mazinan, A.H. ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 240~245
DOI : 10.5370/JEET.2012.7.2.240
A 160 MW drum-type boiler-turbine system is developed in the present research through a multi-multivariable dynamic matrix control (DMC) scheme and a multi-multivariable model approach. A novel intelligence-based decision mechanism (IBDM) is realized to support both model approach and control scheme. In such case, the responsibility of the proposed IBDM is to identify the best multivariable model of the system and the corresponding multivariable DMC scheme to cope with the system at each instant of time in an appropriate manner.
Prototype-based Classifier with Feature Selection and Its Design with Particle Swarm Optimization: Analysis and Comparative Studies
Park, Byoung-Jun ; Oh, Sung-Kwun ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 245~254
DOI : 10.5370/JEET.2012.7.2.245
In this study, we introduce a prototype-based classifier with feature selection that dwells upon the usage of a biologically inspired optimization technique of Particle Swarm Optimization (PSO). The design comprises two main phases. In the first phase, PSO selects P % of patterns to be treated as prototypes of c classes. During the second phase, the PSO is instrumental in the formation of a core set of features that constitute a collection of the most meaningful and highly discriminative coordinates of the original feature space. The proposed scheme of feature selection is developed in the wrapper mode with the performance evaluated with the aid of the nearest prototype classifier. The study offers a complete algorithmic framework and demonstrates the effectiveness (quality of solution) and efficiency (computing cost) of the approach when applied to a collection of selected data sets. We also include a comparative study which involves the usage of genetic algorithms (GAs). Numerical experiments show that a suitable selection of prototypes and a substantial reduction of the feature space could be accomplished and the classifier formed in this manner becomes characterized by low classification error. In addition, the advantage of the PSO is quantified in detail by running a number of experiments using Machine Learning datasets.
SIMM Method Based on Acceleration Extraction for Nonlinear Maneuvering Target Tracking
Son, Hyun-Seung ; Park, Jin-Bae ; Joo, Young-Hoon ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 255~263
DOI : 10.5370/JEET.2012.7.2.255
This paper presents the smart interacting multiple model (SIMM) using the concept of predicted point and maximum noise level. Maximum noise level means the largest value of the mere noises. We utilize the positional difference between measured point and predicted point as acceleration. Comparing this acceleration with the maximum noise level, we extract the acceleration to recognize the characteristics of the target. To estimate the acceleration, we propose an optional algorithm utilizing the proposed method and the Kalman filter (KF) selectively. Also, for increasing the effect of estimation, the weight given at each sub-filter of the interacting multiple model (IMM) structure is varying according to the rate of noise scale. All the procedures of the proposed algorithm can be implemented by an on-line system. Finally, an example is provided to show the effectiveness of the proposed algorithm.
Medical Image Compression Using Quincunx Wavelets and SPIHT Coding
Beladgham, Mohammed ; Bessaid, Abdelhafid ; Taleb-Ahmed, Abdelmalik ; Boucli Hacene, Ismail ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 264~272
DOI : 10.5370/JEET.2012.7.2.264
In the field of medical diagnostics, interested parties have resorted increasingly to medical imaging. It is well established that the accuracy and completeness of diagnosis are initially connected with the image quality, but the quality of the image is itself dependent on a number of factors including primarily the processing that an image must undergo to enhance its quality. This paper introduces an algorithm for medical image compression based on the quincunx wavelets coupled with SPIHT coding algorithm, of which we applied the lattice structure to improve the wavelet transform shortcomings. In order to enhance the compression by our algorithm, we have compared the results obtained with those of other methods containing wavelet transforms. For this reason, we evaluated two parameters known for their calculation speed. The first parameter is the PSNR; the second is MSSIM (structural similarity) to measure the quality of compressed image. The results are very satisfactory regarding compression ratio, and the computation time and quality of the compressed image compared to those of traditional methods.
Power Regulation of Variable Speed Wind Turbines using Pitch Control based on Disturbance Observer
Joo, Young-Jun ; Back, Ju-Hoon ;
Journal of Electrical Engineering and Technology, volume 7, issue 2, 2012, Pages 273~280
DOI : 10.5370/JEET.2012.7.2.273
Most variable speed wind turbines have pitch control mechanisms and one of their objectives is to protect turbines when the wind speed is too high. By adjusting pitch angles of wind turbine, the inlet power and the torque developed by the turbine are regulated. In this paper, the difference between the real wind speed and its rated value is regarded as a disturbance, and a component called disturbance observer (DOB) is added to the pre-designed control loop. The additional DOB based controller estimates the disturbance and generates a compensating signal to suppress the effect of disturbance on the system. As a result, the stability and the performance of the closed loop system guaranteed by an outer-loop controller (designed for a nominal system without taking into account of disturbances) are approximately recovered in the steady state. Simulation results are presented to verify the performance of the proposed control scheme.