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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
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Compensation Algorithm for the Secondary Voltage of a Coupling Capacitor Voltage Transformer by Considering the Hysteresis Characteristics of the Core
Kang, Yong-Cheol ; Zheng, Tai-Ying ; Kang, Hae-Gweon ; Jang, Sung-Il ; Kim, Yong-Gyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1457~1462
This paper proposes a compensating algorithm for the secondary voltage of a coupling capacitor voltage transformer (CCVT) in the time domain by considering the hysteresis characteristics of the core. The proposed algorithm estimates the three error terms i.e. the voltage across the secondary winding parameters, the voltage across the primary winding parameters, and the voltage across the capacitor and the tuning reactor. These three terms are added to the measured secondary voltage to obtain the correct voltage. The algorithm reduces the errors of the CCVT significantly both in the steady state and during a fault. The performance of the algorithm is verified under the various fault conditions by varying the fault distance, the fault inception angle, and the fault impedance with the EMTP generated data. Test results clearly indicate that the algorithm can increase the accuracy of a CCVT significantly under the fault conditions as well as in the steady state. The algorithm helps improve the performance of a protection relay or a metering device.
Integrated Volt/Var Control Algorithm based on the Distributed Load Modeling of Distribution Network
Kim, Young-In ; Lim, Il-Hyung ; Choi, Myeon-Song ; Lee, Seung-Jae ; Lee, Sung-Woo ; Kwon, Sung-Chul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1463~1471
In this paper, a new algorithm of Integrated Volt/Var Control (IVVC) is proposed using Volt/Var control for the Distribution Automation System (DAS) based on the modeling of the distributed load and the distributed current. In the proposed, the load flow based on the modeling of the distributed load and the distributed current are estimated from constants of four terminals using the measurement of the current and power factor from a Feeder Remote Terminal Unit (FRTU). For Integrated Volt/Var Control (IVVC), the gradient method is applied to find optimal solution for tap and capacity control of OLTC (On-Load Tap Changers), SVR (Step Voltage Regulator), and SC (Shunt Condenser). What is more Volt/Var control method is proposed using moving the tie switch as well as IVVC algorithm using power utility control. In the case studies, the estimation and simulation network have been testified in Matlab Simulink.
The Comparison of Reliability for Change Single Loop Configuration in Radial Power Distribution System
Lee, Hee-Tae ; Kim, Jae-Chul ; Kim, Ju-Yong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1472~1478
The domestic power distribution system is operating in an open loop mode; however, it already has a loop structure. Power distribution systems must be changed for bi-directions power supply for smart networks due to a changing of paradigm in electric power industry. The simplest bi-directions distribution networks can make it closing of normally open switch. However, bi-directions power supply is very difficulty to be operated and there are many parts which it must study. This paper presented various models that are able to change a radial system for loop structures. Further, we compared the reliability index for each model by evaluating the amount of improvement reliability required in radial power distribution system. In addition, we calculated CIC(Customer Interruption Cost) for each model by comparing and analyzing.
Analysis on SFCL's Impedance for Protective Coordination in Large Transformer installed in Distribution Substation
Kim, Jin-Seok ; Kim, Myoung-Hoo ; You, Il-Kyoung ; Moon, Jong-Fil ; Lim, Sung-Hun ; Kim, Jae-Chul ; Ahn, Jae-Min ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1479~1484
The introduction of the large transformer due to the large power demand has increased the fault current in power distribution system. The increased fault current can exceed the cut-off ratings of the circuit breaker. As the methods to solve this problem, the superconducting fault current limiter(SFCL) has been notified. However, the limited fault current by SFCL affects the operational characteristics of the protective device such as overcurrent relay. Therefore, the selection of the proper impedance for the SFCL is required to keep overcurrent relay's protective coordination with the SFCL when a large transformer is introduced into the distribution system. In this paper, the SFCL's impedance for protective coordination was investigates in that a large transformer is introduced.
Economic Dispatch Algorithm as Combinatorial Optimization Problems
Min, Kyung-Il ; Lee, Su-Won ; Choi, In-Kyu ; Moon, Young-Hyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1485~1495
This paper presents a novel approach to economic dispatch (ED) with nonconvex fuel cost function as combinatorial optimization problems (COP) while most of the conventional researches have been developed as function optimization problems (FOP). One nonconvex fuel cost function can be divided into several convex fuel cost functions, and each convex function can be regarded as a generation type (G-type). In that case, ED with nonconvex fuel cost function can be considered as COP finding the best case among all feasible combinations of G-types. In this paper, a genetic algorithm is applied to solve the COP, and the
function method is used to calculate ED for the fitness function of GA. The
function method is reviewed briefly and the GA procedure for COP is explained in detail. This paper deals with two kinds of ED problems, namely ED with multiple fuel units (EDMF) and ED with prohibited operating zones (EDPOZ). The proposed method is tested for all the ED problems, and the test results show an improvement in solution cost compared to the results obtained from conventional algorithms.
A Study on the Model of Competitive Electricity Market Considering Emission Trading
Kim, Sang-Hoon ; Lee, Kwang-Ho ; Kim, Wook ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1496~1503
The United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty to stabilize greenhouse gas concentrations in the atmosphere. In order to fulfil the commitments of the countries in an economically efficient way, the UNFCCC adapted the emission trading scheme in the Kyoto Protocol. If the UNFCCC's scheme is enforced in the country, considerable changes in electric power industry are expected due to the imposed greenhouse gas emission reduction. This paper proposes a game theoretic model of the case when generation companies participate in both competitive electricity market and emission market simultaneously. The model is designed such that generation companies select strategically between power quantity and greenhouse gas reduction to maximize their profits in both markets. Demand function and Environmental Welfare of emission trading market is proposed in this model. From the simulation results using the proposed model the impact of the emission trading on generation companies seems very severe in case that the emission prices are significantly high.
The Optimal Operation of Distributed Generation Possessed by Community Energy System Considering Low-Carbon Paradigm
Kim, Sung-Yul ; Shim, Hun ; Bae, In-Su ; Kim, Jin-O ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1504~1511
By development of renewable energies and high-efficient facilities and deregulated electricity market, the operation cost of distributed generation(DG) becomes more competitive. The amount of distributed resource is considerably increasing in the distribution network consequently. Also, international environmental regulations of the leaking carbon become effective to keep pace with the global efforts for low-carbon paradigm. It contributes to spread out the business of DG. Therefore, the operator of DG is able to supply electric power to customers who are connected directly to DG as well as loads that are connected to entire network. In this situation, community energy system(CES) having DGs is recently a new participant in the energy market. DG's purchase price from the market is different from the DG's sales price to the market due to the transmission service charges and etc. Therefore, CES who owns DGs has to control the produced electric power per hourly period in order to maximize the profit. If there is no regulation for carbon emission(CE), the generators which get higher production than generation cost will hold a prominent position in a competitive price. However, considering the international environment regulation, CE newly will be an important element to decide the marginal cost of generators as well as the classified fuel unit cost and unit's efficiency. This paper will introduce the optimal operation of CES's DG connected to the distribution network considering CE. The purpose of optimization is to maximize the profit of CES and Particle Swarm Optimization (PSO) will be used to solve this problem. The optimal operation of DG represented in this paper is to be resource to CES and system operator for determining the decision making criteria.
A Study on the Optimal Method for Mal-function of Re-closer at the Distribution Feeders Interconnected with PV Systems
Kim, Chan-Hyeok ; Park, Hyeon-Seok ; Rho, Dea-Seok ; Shin, Chang-Hoon ; Yoon, Gi-Gab ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1512~1518
Recently, new dispersed power sources such as photovoltaics, wind power, fuel cell etc. are energetically interconnected and operated in the distribution systems, as one of the national projects for alternative energy. This paper deals with the optimal countermeasures for the mal-function of protective devices at primary feeder in distribution systems when new power sources like photovoltaic (PV) systems are interconnected, based on the symmetrical components of short circuit studies. When new power sources are considered to be interconnected to distribution systems, bi-directional power flow and interconnection transformer connection of new power sources may cause the operation problems of protective devices (mainly re-closer), since new power sources can change typical characteristics of distribution systems. Therefore, this paper shows an analysis skill of the mal-functional mechanism of protective relay and proposes the optimal solution for the mal-function problem using the symmetrical components of fault analysis. And, this paper also shows the effectiveness of proposed method by the simulation at the field distribution systems.
A Novel Passive Converter for Improving Drive Characteristics of a Single Phase SRM
Lee, Dong-Hee ; Liang, Jianing ; Ahn, Jin-Woo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1519~1525
This paper presents a novel passive converter for single phase SRM. The proposed passive converter has additional passive power circuit which is consisted by three diodes and one capacitor in the front-end of conventional asymmetric converter to supply a high negative bias during demagnetization. The high negative bias can reduce the demagnetization time and negative torque from tail current in single phase SRM. So, It can extend positive torque region by the extended turn-off position. In this paper, the structure and operating modes of a novel passive converter are introduced with mathematical model. The proposed single phase SRM using passive converter is verified by the computer simulation and experimental results.
A Study on Development of Steering Sensor for Electronic Power Steering
Kim, Byeong-Woo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1526~1531
In this paper, for the first time a new type of narrow-range angle sensor based on inductive effect is introduced and studied. A prototype steering angle sensor is also designed and fabricated to compare the characteristics of the four methods from the viewpoints of sensitivity, linearity and resolution, angle range of the sensor output. This sensor is designed to be sensitive to very small resolution in angle with detected range is scaled down to about 12bit. An intensive investigation has been carried out to study the behaviors of the sensor and optimize its performance by signal compensation. These behaviors are discussed and explained using an analytical and experimental testings. Moreover, Application possibility of the sensor are proposed and a demo device based on the sensor is presented.
Development of RCD Auxiliary Trip Device by using High Precision Current Sensor
Kwak, Dong-Kurl ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1532~1537
Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.
Design of the Protection circuit for Electric ballast with
resonance type Half-bridge Inverter
Choe, Hyeon-Hui ; Park, Chong-Yun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1538~1543
The electric ballast for ceramic metal halide lamp needs a protection circuit to prevent from over voltage and over current in the case that the lamp or the electric ballast are in faults. In this paper, cost-effective and high performance protection circuit is proposed for the electric ballast. The proposed protection circuit is adapted to the electric ballast with
resonance type half bridge inverter. The experimental results demonstrate that the proposed circuit can protect effectively under open and short fault conditions.
Implementation of Voltage Sag/Swell Compensator using Direct Power Conversion
Lee, Sang-Hoey ; Cha, Han-Ju ; Han, Byung-Moon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1544~1550
In this paper, a new single phase voltage sag/swell compensator using direct power conversion is proposed. A new compensator consists of input/output filter, series transformer and direct ac-ac converter, which is a single-phase back-to-back PWM converter without dc-link capacitors. Advantages of the proposed compensator include: simple power circuit by eliminating dc link electrolytic capacitors and thereby, improved reliability and increased life time of the entire compensator; simple PWM strategy or compensating voltage sag/swell at the same time and reduced switching losses in the ac-ac converter. Further, the proposed scheme is able to adopt simple switch commutation method without requiring complex four-step commutation method that is commonly employed in the direct power conversion. Simulation and experimental results are shown to demonstrate the advantages of the new compensator and PWM strategy. A 220V, 3kVA single-phase compensator based on the digital signal processor controller is built and tested.
Study on Power Conditioning System for Fuel Cell Power Generation with 2-Stage DC-DC Converter and Inverter
Ju, Young-Ah ; Oh, Eun-Tae ; Han, Byung-Moon ; Lee, Jun-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1551~1558
This paper proposes a new power conditioning system for the fuel cell power generation, which consists of a LLC resonant DC-DC converter and 3-phase inverter. The LLC resonant converter boosts the fuel cell voltage of 26-48V up to 400V, using the hard-switching boost converter and the high-frequency ZVS half-bridge converter. The operation of proposed power conditioning system was verified through simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was verified through experimental works with a laboratory prototype, which was built with 1.2kW PEM fuel-cell stack, 1kW LLC resonant converter, and 3kW PWM inverter. The proposed system can be utilized to commercialize a real interconnection system for the fuel-cell power generation.
Degradation Behavior and Resistivity Changes After Thermal Aging of Matte Tin-Plated Copper Sheet for Current Collector in Fuel Cell
Kim, Ju-Han ; Kim, Jae-Hun ; Koo, Kyung-Wan ; Keum, Young-Bum ; Jeong, Kwi-Seong ; Ko, Haeng-Jin ; Han, Sang-Ok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1559~1565
Resistivity changes and intermetallic growth after thermal aging of Matter tin-plated copper sheet for current collector in fuel cell were investigated to survey the diffusion of Cu into Sn in interface and surface. The results show that the intermetallic growth and resistivity depended on thermal aging temperature and dwell time. In Sn plate on a Cu substrate, Cu6Sn5(
) and Cu3Sn(
) intermetallics layer were formed at plate/substrate interface. Cu6Sn5(
) intermetallics layer gradually changed Cu3Sn(
). Moreover Cu get through Sn layer and it was diffused in the surface at
. On the other hand, only Cu3Sn(
) intermetallics layer were formed at plate/substrate interface at
. Consequently, the intermetallics formation, thermal condition and oxidation of surface, causes increase in the resistivity of Tin-plated copper sheet.
Effect of MgO Deposition Condition on the Discharge Characteristic of AC-PDP
Jeong, Joo-Young ; Cho, Sung-Yong ; Lee, Don-Kyu ; Lee, Hae-June ; Lee, Ho-Jun ; Park, Chung-Hoo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1566~1571
The discharge electrodes in ac PDP are coated with dielectric layer, and transparent MgO thin films are deposited on the dielectric layer. The main role of the MgO thin films in ac PDP is to protect the dielectric layer from sputtering by ion bombardment in the glow-discharge plasma. An additional important role of the MgO thin film is the high secondary electron emission coefficient which leads the low firing voltage and low cost of the PDP. In this paper, we investigated the relations of the crystal orientation about deposition thickness, deposition rate, temperature of substrate, and distance between the MgO tablet and the substrate. Additionally, we investigated the discharge characteristics of the AC PDP using nano-powder MgO tablet
The Design of Ultra-broadband Power Amplifier using a Negative Feedback
Lee, Han-Young ; Kim, Dae-Jung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1572~1579
In this dissertation ultra-broadband power amplifier(UPA) was designed and fabricated using negative feedback technique. UPA was made of pre-amplifier, drive amplifier and power amplifier. Negative feedback technique was used to achieve ultra-broadband performance. Designed power amplifier has 30dB gain and 2W output power. The load-pull data of power amplifier for optimal power matching was extracted from the measured S-parameter. Fabricated PCB material, permittivity is 4.6 and thickness is 0.8mm, is FR4 and UPA was fabricated 3 modules for comparison of the simulated and measured results. Size of the fabricated pre-amplifier and drive amplifier module is 40mm'50mm'16mm. And from the experimental results, gain of the pre-amplifier module is 9.87dB at 2GHz and flatness is 0.63dB. Experimental result of the drive amplifier module is 10.97dB at 2GHz and flatness of that is 0.26dB. Test result of the power amplifier module is 10.71dB at 2GHz and flatness is 0.72dB. Total size of the power amplifier is 45mm'134mm'16mm. According to the test results, gain of the UPA is 28.98dB at 2GHz and flatness is 1.68dB. Output power was 32.098dBm at 2GHz, 32.154dBm at 1GHz and 31.273dBm at 100MHz.
Design of Monolithically Integrated Vertical Cavity Laser with Depleted Optical Thyristor for Optically Programmable Gate Array
Choi, Woon-Kyung ; Kim, Do-Gyun ; Choi, Young-Wan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1580~1584
We have theoretically analyzed the monolithic integration of vertical cavity lasers with depleted optical thyristor (VCL-DOT) structure and experimentally demonstrated optical logic gates such as AND-gate, OR-gate, and INVERTER implemented by VCL-DOT for an optical programmable gate array. The optical AND and OR gates have been realized by changing a input bias of the single VCL-DOTs and all kinds of optical logic functions are also implemented by adjusting an intensity of the reference input beams into the differential VCL-DOTs. To achieve the high sensitivity, high slope efficiency and low threshold current, a small active region of lasing part and a wide detecting area are simultaneously designed by using a selective oxidation process. The fabricated devices clearly show nonlinear s-shaped current-voltage characteristics and lasing characteristics of a low threshold current with 0.65 mA and output spectrum at 854 nm.
A Method for Calculating the Characteristic Impedance of Substrate Integrated Artificial Dielectric Transmission Lines
Lim, Jong-Sik ; Koo, Ja-Kyung ; Han, Sang-Min ; Jeong, Yong-Chae ; Ahn, Dal ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1585~1591
This paper describes a new method for extracting characteristic impedance of transmission line using Substrate Integrated Artificial Dielectric (SIAD). The new procedure to calculate the characteristic impedance of SIAD transmission line is described with the proper equations and basic transmission line theory. The characteristic impedance is determined as an almost fixed value in the proposed method, while it fluctuates according to frequency in the previous method. As the result, the effective dielectric constant of SIAD transmission line is calculated as a fixed value rather than fluctuating one. In order to show the validity of the proposed method, SIAD microstrip lines are simulated and measured, and characteristic impedances and effective dielectric constant are calculated and compared to the previous method.
LMI-based Design of Reduced Order Output Feedback Sliding Mode Controllers
Choi, Han-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1592~1594
This paper presents an LMI-based method to design a reduced order output feedback sliding mode controller for a class of uncertain systems. Using LMIs we derive an existence condition of a reduced order sliding mode control law. And we give explicit formulas of the gain matrices. Finally, we give a numerical design example, together with a design algorithm.
Optical Disc System Controller Design Based on a Disturbance Detector
Choi, Byung-Ho ; Choi, Ga-Hyung ; Yoon, Tae-Sung ; Park, Jin-Bae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1595~1604
An Optical disk driver is used in many electronic products besides the computers. In particular, the demands are recently increased as an optical disk player/recorder in the mobile products such as camcorder, portable player or in the home theater appliances, etc. However, the more the mobility is emphasized, the more the optical disk player is exposed to the disturbance inputs. For reducing the possibility of malfunction of the optical disk, we propose a nonlinear controller using the disturbance detecting algorithm based on the Kalman filter. Actual experiments were executed to verify the performance of the proposed method. The proposed method controls the tracking error signal within
Increasing the SLAM performance by integrating the grid-topology based hybrid map and the adaptive control method
Kim, Soo-Hyun ; Yang, Tae-Kyu ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1605~1614
The technique of simultaneous localization and mapping is the most important research topic in mobile robotics. In the process of building a map in its available memory, the robot memorizes environmental information on the plane of grid or topology. Several approaches about this technique have been presented so far, but most of them use mapping technique as either grid-based map or topology-based map. In this paper we propose a frame of solving the SLAM problem of linking map covering, map building, localizing, path finding and obstacle avoiding in an automatic way. Some algorithms integrating grid and topology map are considered and this make the SLAM performance faster and more stable. The proposed scheme uses an occupancy grid map in representing the environment and then formulate topological information in path finding by A
algorithm. The mapping process is shown and the shortest path is decided on grid based map. Then topological information such as direction, distance is calculated on simulator program then transmitted to robot hardware devices. The localization process and the dynamic obstacle avoidance can be accomplished by topological information on grid map. While mapping and moving, pose of the robot is adjusted for correct localization by implementing additional pixel based image layer and tracking some features. A laser range finer and electronic compass systems are implemented on the mobile robot and DC geared motor wheels are individually controlled by the adaptive PD control method. Simulations and experimental results show its performance and efficiency of the proposed scheme are increased.
The Design of Optimized Type-2 Fuzzy Neural Networks and Its Application
Kim, Gil-Sung ; Ahn, Ihn-Seok ; Oh, Sung-Kwun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1615~1623
In order to develop reliable on-site partial discharge (PD) pattern recognition algorithm, we introduce Type-2 Fuzzy Neural Networks (T2FNNs) optimized by means of Particle Swarm Optimization(PSO). T2FNNs exploit Type-2 fuzzy sets which have a characteristic of robustness in the diverse area of intelligence systems. Considering the on-site situation where it is not easy to obtain voltage phases to be used for PRPDA (Phase Resolved Partial Discharge Analysis), the PD data sets measured in the laboratory were artificially changed into data sets with shifted voltage phases and added noise in order to test the proposed algorithm. Also, the results obtained by the proposed algorithm were compared with that of conventional Neural Networks(NNs) as well as the existing Radial Basis Function Neural Networks (RBFNNs). The T2FNNs proposed in this study were appeared to have better performance when compared to conventional NNs and RBFNNs.
Design of Optimized Interval Type-2 Fuzzy Controller and Its Application
Jang, Han-Jong ; Oh, Sung-Kwun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1624~1632
In this study, we introduce the design methodology of an optimized Interval Type-2 fuzzy controller. The fixed MF design of type-1 based FLC leads to the difficulty of rule-based control design for representing the linguistically uncertain expression. In the Type-2 FLC as the expanded type of Type-1 FLC, we can effectively improve the control characteristic by using the footprint of uncertainty(FOU) of membership function. Type-2 FLC has a robust characteristic in the unknown system with unspecific noise when compared with Type-1 FLC. Through computer simulation as well as practical experiment, we compare their performance by applying both the optimized Type-1 and Type-2 fuzzy cascade controllers to ball and beam system. To evaluate each controller performance, we consider controller characteristic parameters such as maximum overshoot, delay time, rise time, settling time and steady-state error.
Sidelobe Suppression Technique in OFDM Systems for Spectrum Sharing
Hwang, Hu-Mor ; Ahmed, Saleem ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1633~1637
We propose a new technique for sidelobe suppression in orthogonal frequency division multiplexing (OFDM) systems. Sidelobe suppression is an essential technique to design OFDM based overlay system. The proposed technique is based on the combination of the multiple choice sequence (MCS) with the conventional windowing of OFDM signal in time domain. The MCS is choosing the one sequence which has lowest power in sidelobes from the produced set of sequences. The main advantage of proposed technique is that it fully utilizes the available bandwidth to transmit data. Simulation results show that by combining MCS with conventional windowing technique, the sidelobes in OFDM system can be significantly reduced
Noise Reduction Technique by Three-Points Ensemble Averaging in Uroflowmetry
Choi, Seong-Su ; Lee, In-Kwang ; Lee, Sang-Bong ; Park, Jun-Oh ; Lee, Su-Ok ; Cha, Eun-Jong ; Kim, Kyung-Ah ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1638~1643
Uroflowmetry is a convenient clinical test to screen the benign prostatic hyperplasia(BPH) common in the aged men. A load cell is located beneath the urine container to measure the weight of urine. However, it is sensitive to the impact applied on the bottom of the container by the urine stream, which could be a noise source lowering the reliability of the system. With this aim, our study proposed a noise reduction technique by computing ensemble average of the weighted signals that were acquired from three-load cells forming a regular triangle beneath the urine container. Simulated urination experiment was performed with three different collection methods, all of which demonstrated significant noise reduction by ensemble averaging. Furthermore, the best results can be obtained without any special urine collection devices. Thus, our novel method can be usefully applied to uroflowmetry for enhancing measurement in terms of accuracy and reliability.
A Transconductance Driven-Right-Leg Circuit with Improved Guarding Circuit
Hwang, In-Duk ;
The Transactions of The Korean Institute of Electrical Engineers, volume 58, issue 8, 2009, Pages 1644~1650
An improved guarding circuit is applied to a transconductance driven-right-leg circuit to decrease common-mode current at measurement electrodes due to power-line interference. After showing conventional guarding circuit is instable due to gain-peaking when used with a transconductance DRL circuit, the effect of the proposed guarding circuit modified to suppress the gain-peaking by inserting a series resistor between shields and a shield driver was analyzed. It is shown that, besides stability, the proposed guarding circuit provides two other advantages: 1) The gain of the shield driver can be set to be unit nominally. 2) The loop gain of the transconductance DRL loop can be increased due to pole-zero canceling. The proposed circuit was implemented and the advantages were confirmed.