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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 60, Issue 12 - Dec 2011
Volume 60, Issue 11 - Nov 2011
Volume 60, Issue 10 - Oct 2011
Volume 60, Issue 9 - Sep 2011
Volume 60, Issue 8 - Aug 2011
Volume 60, Issue 7 - Jul 2011
Volume 60, Issue 6 - Jun 2011
Volume 60, Issue 5 - May 2011
Volume 60, Issue 4 - Apr 2011
Volume 60, Issue 3 - Mar 2011
Volume 60, Issue 2 - Feb 2011
Volume 60, Issue 1 - Jan 2011
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Control Algorithm of Hybrid System for Feeder Flow Mode Operation in Microgrid
Moon, Dae-Seong ; Seo, Jae-Jin ; Kim, Yun-Seong ; Won, Dong-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 1~7
DOI : 10.5370/KIEE.2011.60.1.001
Active power control scheme for distributed generation in microgrid consists of feeder flow control and unit power control. Feeder flow control is more useful than the unit power control for demand-side management, because microgrid can be treated as a dispatchable load at the point of common coupling(PCC). This paper presents detailed descriptions of the feeder flow control scheme for the hybrid system in microgrid. It is divided into three parts, namely, the setting of feeder flow reference range for stable hybrid system operation, feeder flow control algorithm depending on load change in microgrid and hysteresis control. Simulation results using the PSCAD/EMTDC are presented to validate the inverter control method for a feeder flow control mode. As a result, the feeder flow control algorithm for the hybrid system in microgrid is efficient for supplying continuously active power to customers without interruption.
Setting Method of a Percentage Current Differential Relay for Transformer Protection
Kim, Su-Hwan ; Kang, Sang-Hee ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 8~13
DOI : 10.5370/KIEE.2011.60.1.008
A percentage current differential relay is widely used for transformer protection. Because many percentage current differential relays recently use modified methods instead of conventional methods for deciding the operating characteristics of the large current region, in this paper, the operating region of a percentage current differential relay is analyzed in input-output current domain instead of operating-restraint current domain. An effective method to set the operating region when a CT is saturated is proposed with a series of investigations comparing a conventional method with the proposed modified method. The performance of the proposed method is evaluated for internal and external faults of a power transformer having the voltage rating of 345/154kV. EMTP-RV is used for the relaying data collection.
The Study of Transient Coupling between AC and DC lines on the Same Transmission Tower
Yoon, Jong-Su ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 14~19
DOI : 10.5370/KIEE.2011.60.1.014
The implemetation of the AC and DC lines on the same transmission tower is an economical and practical approaching that increase the power transmission capacity of an existing transmission corridor. But, In this case, Inductive and capacitive coupling between AC and DC lines on the same tower should be investigated in advance. According to the installation plan of
60MW bipole HVDC in Jeju island, KOREA that will be commissioned until 2011, DC lines will parallely operate with 154kV 2 AC lines in existed 154kV AC 4 lines transmission tower. This paper presents the transient analysis results about the interaction between 154kV AC and 80kV DC lines in the same transmission tower.
A Study on the Application of SFCL on 22.9 kV Bus Tie for Parallel Operation of Power Main Transformers in a Power Distribution System
On, Min-Gwi ; Kim, Myoung-Hoo ; Kim, Jin-Seok ; You, Il-Kyoung ; Lim, Sung-Hun ; Kim, Jae-Chul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 20~25
DOI : 10.5370/KIEE.2011.60.1.020
This paper analyzed the application of Superconducting Fault Current Limiter (SFCL) on 22.9 [kV] bus tie in a power distribution system. Commonly, the parallel operations of power main transformers offer a lot of merits. However, when a fault occurs in the parallel operation of power main transformer, the fault currents might exceed the interruption capacity of existing protective devices. To resolve this problem, thus, the SFCL has been studied as the fascinating device. In case that, Particularly, the SFCL could be installed to parallel operation of various power main transformers in power distribution system of the Korea Electric Power Corporation (KEPCO) on 22.9 [kV] bus tie, the effect of the resistance of SFCL could reduce the increased fault currents and meet the interruption capacity of existing protective devices by them. Therefore, we analyzed the effect of application and proposed the proper impedance of the R-type SFCL on 22.9 [kV] bus tie in a power distribution system using PSCAD/EMTDC.
A Loop Configuration Algorithm Considering Constraints in Distribution System
Cho, Bo-Hyeon ; Cho, Sung-Min ; Park, Jin-Hyun ; Sin, Hee-Sang ; Kim, Jae-Chul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 26~31
DOI : 10.5370/KIEE.2011.60.1.026
In this paper, we focused on the loop distribution system to solve the international issues of energy depletion and global warming. The conventional method of reconfiguration of distribution system was moving open points of switches from an actual switch position to another, while an appropriate switch must be opened to preserve the radial structure and this procedure is continued til there is no further loss reduction. However, the loop distribution system is the best optimization method to minimize loss than the other methods which is preserving radial structure. So we analyzed 3 types of loop distribution system upgraded from radial distribution system by changing normally open switch to normally closed switch. The simple 3 types of model system for simulation were composed, and each types of loop system were simulated in accordance with varying parameters. As a result of simulations, the loss reduction was different for each types of loop distribution system and each loop types have constraints for composing loop distribution system. The algorithms propose the method how to construct loop distribution system regarding constraints. Type I that needs least requirements get least loss reduction and Type III that needs most requirements get maximum loss reduction. On the other hand, Type I was most feasible distribution system to be realized.
Economic Assessment of a Wind Farm Project Using Least Square Monte-Carlo (LSMC) Simulation
Kim, Jin-A ; Lee, Jong-Uk ; Lee, Jae-Hee ; Joo, Sung-Kwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 32~35
DOI : 10.5370/KIEE.2011.60.1.032
The economic value of a wind farm project is influenced by various risk factors such as wind power output and electricity market price. In particular, there is uncertainty in the economic evaluation of a wind farm project due to uncertain wind power outputs, which are fluctuated by weather factors such as wind speed, and volatile electricity market prices. This paper presents a systematic method to assess the economic value and payback period of a wind farm project using Least Square Monte-Carlo (LSMC) simulation. Numerical example is presented to validate the effectiveness of the proposed economic assessment method for a wind farm project.
Supervisory Protection System of Microgird Interconnected to Low Voltage Grids
Jyung, Tae-Young ; Baek, Young-Sik ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 36~42
DOI : 10.5370/KIEE.2011.60.1.036
This paper mainly proposes the protective coordination scheme of the microgrid system. The microgrid protection is identical to the conventional protection system separating the normal part and contingency part to reduce damage when the contingency occur at power cables, facilities. But they are different in the protection type. The conventional protection system only considers unidirectional current. However the microgrid protection should be considered not only unidirectional current but also backfeed current because various microsources and loads are installed in the microgrid system. In case the contingency occurs in microsource, when microgrid is interconnected to grid, the protection system should be configured to not separate microgrid from grid before the microsource is isolated to microgrid. And in case of fault occur in power system, the microsources should not isolated to microgrid before the static switch at PCC is tripped to separate from power system. Considering these characteristic of microgird, this paper proposes the protective coordination scheme of microgrid and implemented the on-line real time monitoring system. Especially in case the microgrid is connected to low voltage distribution system with 220/380V voltage level, the proposed protection method with power IT technology can solve the problems when the existing protective devices only applied to the microgrid system.
Improved Coordination Method for Back-up Protection Schemes Based on IEC 61850
Kim, Hyung-Kyu ; Kang, Sang-Hee ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 43~49
DOI : 10.5370/KIEE.2011.60.1.043
A distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, Zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome this problem clearly, this paper describes an improved backup protection coordination scheme using an IEC 61850-based distance relay for transformer backup protection. IEC 61850-based IED(Intelligent Electronic Device) and the network system based on the kernel 2.6 LINUX are realized to verify the proposed method. And laboratory tests to estimate the communication time show that the proposed coordination method is reliable enough for the improved backup protection scheme.
Performance Evaluation of Small-Scaled Wind Power Generator with Outer Permanent Magnet Rotor considering Electromagnetic Losses (2) - Electromagnetic Losses and Performance Analysis -
Ko, Kyoung-Jin ; Jang, Seok-Myeong ; Choi, Jang-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 50~62
DOI : 10.5370/KIEE.2011.60.1.050
In this paper, analytical techniques for performance characteristics analysis of wind power generator with outer permanent magnet rotor are proposed. Furthermore, the proposed analytical techniques are validated by performance experiments of the manufactured generator. In this part, characteristic equations of losses such as copper loss, core loss are derived. Using the derived loss characteristic equations, electrical parameters obtained in  and d-q axes method, constant load and constant speed characteristics of wind power generator are analyzed. And then, to analyze performance of wind power system according to wind speed, d-q analysis model considering wind turbine characteristics is proposed. Finally, the obtained performance characteristics results are validated in comparison with those by experiments.
Design and Operating Characteristics of Cylindrical Linear Motor for Long Stroke Precision Stage
An, Geuk-Sub ; Kim, Houng-Joong ; Ahn, Jin-Woo ; Koseki, Takafumi ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 63~70
DOI : 10.5370/KIEE.2011.60.1.063
This paper presents the design and operating characteristics of the novel cylindrical linear motor which is designed for the long stroke XY stage. In the long stroke structure, the air gap is changed by the distortion and bending effects, and it makes additional position error in the XY stage. In order to consider the distortion and bending effects of the long stroke, the field part of the cylindrical linear motor is designed as an open structure, and the stroke is supported by the bridge guide which is positioned in the open field part. The mechanical bridge guide can reduce the bending effects of the stroke and can keep a constant air gap. The detailed design process of the proposed cylindrical linear motor is presented in this paper. The proposed motor is analyzed by the 3D FEM technology. The practical XY stage which uses the proposed motor is tested to verify the propose novel cylindrical linear motor. The FEM and experimental results show the effectiveness of the proposed motor.
A Variable Voltage Control Method of the High Voltage DC/DC Converter for a Hybrid or Battery Electric Vehicle
Kwon, Tae-Suk ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 71~77
DOI : 10.5370/KIEE.2011.60.1.071
An analysis, which is focused on electrical losses of an electrical propulsion system with High voltage DC/DC Converter (HDC) for a hybrid and an electric vehicle, is presented. From the analysis, it can be known that the electrical losses are closely related to the dc link voltage of the HDC, and there is an optimal dc link voltage which minimizes the losses. In this paper, the method to decide the optimal dc link voltage is proposed and the comparison on the losses by the control methods of the dc link voltage, during a driving cycle, is performed and the result is also presented.
A Single Phase Inverter Using the Central Arm
Lee, Ho ; Lee, Hwa-Choon ; Kim, Seung-Ryong ; Park, Sung-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 78~84
DOI : 10.5370/KIEE.2011.60.1.078
In this paper, the switching frequency and THD for the reduction instead of traditional single phase inverter using a new type of central arm of the single phase inverter is proposed. The proposed single phase inverter topology, the existing one to add a arm by two-way central switch 3-level output voltage can be raised and, central arm, especially one or two of the switches by using a switch to the diode current switching algorithm was simplified. During the dead time because of this, depending on the direction of the current level does not appear in any other existing level compared to the inverter output voltage level of the THD has the advantage that less can be. The simulation and experimental results verified the validity of the proposed topology.
A Study on the Contact Power by Coating Material of Spray in AT Feeding Method
Kim, Min-Seok ; Kim, Min-Kyu ; Park, Yong-Gul ; Lee, Jong-Woo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 85~92
DOI : 10.5370/KIEE.2011.60.1.085
Main characteristic in railroad is the guided movement of the wheel by the track through a metal-to-metal contact, conferring to the rail vehicle a single degree of freedom. There are defects such as head check, shelling, corrugation, squats etc in surface of the rail by interface between the wheel and rail. These defects bring about reducing the life-cycle of rails and track components and increasing noises. In case of bad conditions, it is possible to happen to full-scale accident such as derailment. Recently, the track capacity has been increased for increasing speed and operation efficiency. So, maintenance and indirect cost have been increased. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. Rails are used as the earth in electrical railroad systems. Currently traction return current is flowed through wheels of trains. In case of rails coated, problems are caused in the contact power between wheel and coating material of spray. In this paper, electric model is presented in the AT feeding method. In case of rails coated, electric model is presented. Also, standard resistance of the ceramic is demonstrated by contact power between wheel and coating material of spray.
An Algorithm for the Asynchronous PRT Vehicle Control System
Chung, Sang-Gi ; Jeong, Rag-Kyo ; Kim, Baek-Hyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 93~99
DOI : 10.5370/KIEE.2011.60.1.093
A PRT vehicle's control method is presented in this paper. In the asynchronous vehicle control system, vehicles follow their leading vehicles. Leading vehicles are defined differently among the different types of track. The main topic of this paper is to present a method to define the leading vehicle among different types of track and the calculation algorithm of the safety length the following vehicle must maintain. Simulation program is developed using the algorithm and the results of the test run are presented. An asynchronous PRT vehicle control algorithm was presented by Szillat in the paper "A low level PRT Microsimulation, Dissertation, University of Bristol, 2001". But it is different from the algorithm in this paper. In the algorithm proposed by Markus, vehicles in the merging track are controlled synchronously, and its safety distance between the leading and the following car is evaluated after the establishment of the complicated future time-location table instead of simple equations proposed in this paper.
Experimental Investigation on High Efficient Electrolytes of Electrochemical Photovoltaic Cells
Kim, Doo-Hwan ; Han, Chi-Hwan ; Sung, Youl-Moon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 100~104
DOI : 10.5370/KIEE.2011.60.1.100
In this work, an optimum condition of electrolytes preparation for photovoltaic cells application was investigated experimentally in terms of impedance and conversion efficiency of the cells. 3-methoxyppropionitrie and redox pairs with LiI and
were used as stable solvents for fabrication of electrolyte. Efficiency comparison of the prepared cells carried out for various additives and ionic liquids. From the results, there was an optimum concentration (about 0.3 M) of ionic liquids for efficient cell fabrication. For case of electrolyte using single DMAp additive, the maximum conversion efficiency of the cell was 6.4%(
: 14.4 mA/
, ff: 0.57). For case of electrolyte using both DMAp and CEMim additives, the maximum conversion efficiency of the cell was 7.2%(
: 16 mA/
, ff: 0.57). From the result of electrochemical impedance measurement, both Z1 and Z3 values of binary additives-based cell decreased compared to those of single additive-based. This is due to the decreased in internal and charge transfer resistivities of the cells.
A p-n Heterojunction Diode Constructed with A p-Si Nanowire and An n-ZnO Nanoparticle Thin-Film by Dielectrophoresis
Kim, Kwang-Eun ; Lee, Myeong-Won ; Yun, Jung-Gwon ; Kim, Sang-Sig ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 105~108
DOI : 10.5370/KIEE.2011.60.1.105
Newly-developed fabrication of a p-n heterojunction diode constructed with a p-Si nanowire (NW) and an n-ZnO nanoparticle (NP) thin-film by the dielectrophoresis (DEP) technique is demonstrated in this study. With the bias of 20 Vp-p at the input frequency of 1 MHz, the most efficient assembly of the n-ZnO NPs is shown for the fabrication of the p-n heterojunction diode with a p-Si NW. The p-n heterojunction diode fabricated in this study represents current rectifying characteristics with the turn on voltage of 1.1 V. The diode can be applied to the fabrication of optoelectrical devices such as photodetectors, light-emitting diodes (LEDs), or solar cells based on the high conductivity of the NW and the high surface to volume ratio of the NP thin film.
A Study on the Reduction of Conducted Noise Emission from an Interior LED Lighting Module with TRIAC Dimming Control
Seo, Jung-Nam ; Yu, Yong-Su ; Yeo, In-Seon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 109~113
DOI : 10.5370/KIEE.2011.60.1.109
This paper analyzes the noise sources of an LED lighting module with TRIAC dimming control and proposes an improved EMI filter design for the reduction of conducted noise emission. TRIAC dimming invokes problems of input oscillation and capacitor overvoltage at the lighting module. The proposed double LC filter reduces high noise level from the circuit. The experimental and simulation results show that this approach can make significant contributions to the reduction of conducted noise emission from an LED lighting module with TRIAC dimming control.
Fabrication of Transparent Conductive Oxide-less Dye-Sensitized Solar Cells Consisting of Titanium Double Layer Electrodes
Shim, Choung-Hwan ; Kim, Yun-Gi ; Kim, Dong-Hyun ; Lee, Hae-June ; Lee, Ho-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 114~118
DOI : 10.5370/KIEE.2011.60.1.114
Dye-Sensitized Solar Cells(DSSCs) consist of a titanium dioxide(
) nano film of the photo electrode, dye molecules on the surface of the
film, an electrolyte layer and a counter electrode. But two transparent conductive oxide(TCO) substrates are estimated to be about 60[%] of the total cost of the DSSCs. Currently novel TCO-less structures have been investigated in order to reduce the cost. In this study, we suggested a TCO-less DSSCs which has titanium double layer electrodes. Titanium double layer electrodes are formed by electron-beam evaporation method. Analytical instruments such as electrochemical impedance spectroscopy, scanning electron microscope were used to evaluate the TCO-less DSSCs. As a result, the proposed structure decreases energy conversion efficiency and short-circuit current density compared with the conventional DSSCs structure with FTO glass, while internal series impedance of TCO-less DSSCs using titanium double layer electrodes decreases by 27[%]. Consequently, the fill factor is improved by 28[%] more than that of the conventional structure.
A Comparative Study on Discharge Characteristics of FHD and QFHD AC PDP
Choi, Yong-Suk ; Heo, Jun ; Kim, Dong-Hyun ; Lee, Hae-June ; Lee, Ho-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 119~123
DOI : 10.5370/KIEE.2011.60.1.119
We have investigated the luminous efficiency of various cell resolution and structure from 50" FHD to 50" QFHD Plasma Display. The suggested test panels have two different cell array types which are the delta and matrix cell array type. The results showed that, in the case of the suggested QFHDs, the firing and sustain voltage were increased and voltage margin was decreased. These results are caused by the reduced wall voltage and increased charged particle loss, at the side wall. The luminance of the suggested QFHDs was lower from 20% to 40% than that of the suggested FHDs and the power consumption was higher from 42% to 83% than that of the suggested FHDs. In conclusion, the maximum luminous efficiency of the suggested QFHD(D110) has reached about 38%, compared with suggested FHDs(
Design and Implementation on High Efficient EPMS(Energy-Power Management System) for USN Sensor Node Using Self-Charging Module
Kim, Hyun-Woong ; Park, Hee-Jeong ; Lim, Se-Mi ; Oh, Jong-Hwa ; Roh, Hyoung-Hwan ; Park, Jun-Seok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 124~130
DOI : 10.5370/KIEE.2011.60.1.124
In this paper, We design and implementation of Self-Charging Module for charging to battery which obtaining the environment inergy such as solar energy. The power chared battery through the charging module send to sensor node. And implementation of System Activation Module(SAM) based on ID system and Dynamic Power Management Module(DPM) with SPO(Self Power Off). This system consume power only communication between the sensor nodes. We verification this system by implementing the high efficiency poweer management system.
EM Analysis of High Voltage Connector for Hybrid/Electric Vehicle
Lee, June-Sang ; Kim, Jong-Min ; Nam, Ki-Hoon ; Bae, Hyeon-Ju ; Sung, Jin-Tae ; Nah, Wan-Soo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 131~137
DOI : 10.5370/KIEE.2011.60.1.131
This paper analyzes EM(Electromagnetic) characteristic in the high voltage connector for the hybrid electric vehicle. The connector bridges the electrical components and helps transferring electrical power and signal through it. The necessity of the high voltage and current connector development is emphasized because the hybrid electric vehicle recently uses the high voltage and current more than 500V and 80A. So far there has not been international EMC (Electromagnetic Compatibility) standards to limit the RE(Radiation Emission) from the connector for the hybrid electric vehicle. In this paper we analyzed EM characteristic of the 288V, 65A connector to check if the RE from the high voltage connector could be within the RE limit standard of vehicle. Three-dimensional modeling and simulation was conducted by using MWS(Microwave Studio) of the CST corporation, and the result was compared with the measured RE data, which showed good coincidence each other.
LMI-based Design of Output Feedback Integral Sliding Mode Controllers
Choi, Han-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 138~141
DOI : 10.5370/KIEE.2011.60.1.138
This paper presents an LMI-based method to design an output feedback integral sliding mode controller for a class of uncertain systems. Using LMIs we derive an existence condition of a sliding surface. And we give a switching feedback control law. Finally, we give a numerical design example in order to show the effectiveness of the proposed method.
Multiple Model Adaptive Estimation of the SOC of Li-ion battery for HEV/EV
Jung, Hae-Bong ; Kim, Young-Chol ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 142~149
DOI : 10.5370/KIEE.2011.60.1.142
This paper presents a new state of charge(SOC) estimation of large capacity of Li-ion battery (LIB) based on the multiple model adaptive estimation(MMAE) method. We first introduce an equivalent circuit model of LIB. The relationship between the terminal voltage and the open circuit voltage(OCV) is nonlinear and may vary depending on the changes of temperature and C-rate. In this paper, such behaviors are described as a set of multiple linear time invariant impedance models. Each model is identified at a temperature and a C-rate. These model set must be obtained a priori for a given LIB. It is shown that most of impedances can be modeled by first-order and second-order transfer functions. For the real time estimation, we transform the continuous time models into difference equations. Subsequently, we construct the model banks in the manner that each bank consists of four adjacent models. When an operating point of cell temperature and current is given, the corresponding model bank is directly determined so that it is included in the interval generated by four operating points of the model bank. The MMAE of SOC at an arbitrary operating point (T
[A]) is performed by calculating a linear combination of voltage drops, which are obtained by four models of the selected model bank. The demonstration of the proposed method is shown through simulations using DUALFOIL.
Stabilized Adaptive Fuzzy LMS Algorithms for Active Noise Control
Ahn, Dong-Jun ; Baek, Kwang-Hyun ; Nam, Hyun-Do ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 150~155
DOI : 10.5370/KIEE.2011.60.1.150
In an active noise control systems, an IIR filter may cause a problem in stability beacause of its poles. For IIR filter, its poles goes sometimes out of a unit circle in a z-plane in the transition state, where the adaptive algorithm converges to the optimum value, which causes the system to diverge. Fuzzy LMS algorithm has a better convergence property than conventional LMS algorithms, but is not applicable to IIR filter because of the reasons. Stabilized adaptive algorithm could be improves stability by moving the pole of IIR filer toward the origin forcibly in the transient state, and by introducing forgetting factor to maintain the optimum convergence when it reaches to the steady state. In this paper, We proposed stabilized adaptive fuzzy LMS algorithms with IIR filter structures, for single channel active noise control with ill conditioned signal case. Computer simulations were performed to show the effectiveness of a proposed algorithm.
Design and Implementation of Hardware for various vision applications
Yang, Keun-Tak ; Lee, Bong-Kyu ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 156~160
DOI : 10.5370/KIEE.2011.60.1.156
This paper describes the design and implementation of a System-on-a-Chip (SoC) for pattern recognition to use in embedded applications. The target Soc consists of LEON2 core, AMBA/APB bus-systems and custom-designed accelerators for Gaussian Pyramid construction, lighting compensation and histogram equalization. A new FPGA-based prototyping platform is implemented and used for design and verification of the target SoC. To ensure that the implemented SoC satisfies the required performances, a pattern recognition application is performed.
Development of Vision based Autonomous Obstacle Avoidance System for a Humanoid Robot
Kang, Tae-Koo ; Kim, Dong-Won ; Park, Gwi-Tae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 161~166
DOI : 10.5370/KIEE.2011.60.1.161
This paper addresses the vision based autonomous walking control system. To handle the obstacles which exist beyond the field of view(FOV), we used the 3d panoramic depth image. Moreover, to decide the avoidance direction and walking motion of a humanoid robot for the obstacle avoidance by itself, we proposed the vision based path planning using 3d panoramic depth image. In the vision based path planning, the path and walking motion are decided under environment condition such as the size of obstacle and available avoidance space. The vision based path planning is applied to a humanoid robot, URIA. The results from these evaluations show that the proposed method can be effectively applied to decide the avoidance direction and the walking motion of a practical humanoid robot.
Mapping Tool for Semantic Interoperability of Clinical Terms
Lee, In-Keun ; Hong, Sung-Jung ; Cho, Hune ; Kim, Hwa-Sun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 167~173
DOI : 10.5370/KIEE.2011.60.1.167
Most of the terminologies used in medical domain is not intended to be applied directly in clinical setting but is developed to integrate the terms by defining the reference terminology or concept relations between the terms. Therefore, it is needed to develop the subsets of the terminology which classify categories properly for the purpose of use and extract and organize terms with high utility based on the classified categories in order to utilize the clinical terms conveniently as well as efficiently. Moreover, it is also necessary to develop and upgrade the terminology constantly to meet user's new demand by changing or correcting the system. This study has developed a mapping tool that allows accurate expression and interpretation of clinical terms used for medical records in electronic medical records system and can furthermore secure semantic interoperability among the terms used in the medical information model and generate common terms as well. The system is designed to execute both 1:1 and N:M mapping between the concepts of terms at a time and search for and compare various terms at a time, too. Also, in order to enhance work consistency and work reliability between the task performers, it allows work in parallel and the observation of work processes. Since it is developed with Java, it adds new terms in the form of plug-in to be used. It also reinforce database access security with Remote Method Invocation (RMI). This research still has tasks to be done such as complementing and refining and also establishing management procedures for registered data. However, it will be effectively used to reduce the time and expenses to generate terms in each of the medical institutions and improve the quality of medicine by providing consistent concepts and representative terms for the terminologies used for medical records and inducing proper selection of the terms according to their meaning.
Development of the UPC-A Barcode Recognition Algorithm for Smartphone Applications
Lee, Sang-Joon ; Lee, Sang-Yong ; Lee, Young-Bum ; Lee, Myoung-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 174~183
DOI : 10.5370/KIEE.2011.60.1.174
This paper is about a bar code decoding algorithm developed for smart phone applications. The algorithm consists of bar code data extraction procedure, bar code signal estimation procedure, and bar code decoding procedure. To detect the peak bar code module, a DSTW had been applied because of its outstanding performance in ECG peak detection. In order to minimize errors due to non-uniform light effect, the proposed algorithm was acted as a baseline wandering filter based on module peaks detection. The algorithm had been tested to evaluate the performance under the conditions of blurring, non-uniformed light and white noises. The algorithm had shown excellent performance in reconstruction of bar code decoding, compared to other conventional methods. In order to show the possibility of applying the algorithm to a smart phone, a real UPC-A type 150 bar code pictures obtained from a smart phone camera was applied to the algorithm, achieving the correct recognition rate of 97.33%.
Identification Methodology of FCM-based Fuzzy Model Using Particle Swarm Optimization
Oh, Sung-Kwun ; Kim, Wook-Dong ; Park, Ho-Sung ; Son, Myung-Hee ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 184~192
DOI : 10.5370/KIEE.2011.60.1.184
In this study, we introduce a identification methodology for FCM-based fuzzy model. The two underlying design mechanisms of such networks involve Fuzzy C-Means (FCM) clustering method and Particle Swarm Optimization(PSO). The proposed algorithm is based on FCM clustering method for efficient processing of data and the optimization of model was carried out using PSO. The premise part of fuzzy rules does not construct as any fixed membership functions such as triangular, gaussian, ellipsoidal because we build up the premise part of fuzzy rules using FCM. As a result, the proposed model can lead to the compact architecture of network. In this study, as the consequence part of fuzzy rules, we are able to use four types of polynomials such as simplified, linear, quadratic, modified quadratic. In addition, a Weighted Least Square Estimation to estimate the coefficients of polynomials, which are the consequent parts of fuzzy model, can decouple each fuzzy rule from the other fuzzy rules. Therefore, a local learning capability and an interpretability of the proposed fuzzy model are improved. Also, the parameters of the proposed fuzzy model such as a fuzzification coefficient of FCM clustering, the number of clusters of FCM clustering, and the polynomial type of the consequent part of fuzzy rules are adjusted using PSO. The proposed model is illustrated with the use of Automobile Miles per Gallon(MPG) and Boston housing called Machine Learning dataset. A comparative analysis reveals that the proposed FCM-based fuzzy model exhibits higher accuracy and superb predictive capability in comparison to some previous models available in the literature.
Optimizing Checkpoint Intervals for Real-Time Multi-Tasks with Arbitrary Periods
Kwak, Seong-Woo ; Yang, Jung-Min ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 193~200
DOI : 10.5370/KIEE.2011.60.1.193
This paper presents an optimal checkpoint strategy for fault-tolerance in real-time systems. In our environment, multiple real-time tasks with arbitrary periods are scheduled in the system by Rate Monotonic (RM) algorithm, and checkpoints are inserted at a constant interval in each task while the width of interval is different with respect to the task. We propose a method to determine the optimal checkpoint interval for each task so that the probability of completing all the tasks is maximized. Whenever a fault occurs to a checkpoint interval of a task, the execution time of the task would be prolonged by rollback and re-execution of checkpoints. Our scheme includes the schedulability test to examine whether a task can be completed with an extended execution time. A numerical experiment is conducted to demonstrate the applicability of the proposed scheme.
The Improvement in Signal Integrity of FT-ICR MS
Kim, Seung-Yong ; Kim, Seok-Yoon ; Kim, Hyun Sik ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 201~204
DOI : 10.5370/KIEE.2011.60.1.201
For efficient noise reduction in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrum, a new algorithm was proposed. The suggested algorithm reduces white and electrical noise, and it improves signal-to-noise ratio. This algorithm has been optimized to reduce the noise more efficiently using the traces of signal level. The algorithm has been efficiently combined with derivative window to improve the resolution as well S/N. Time domain data was corrected for DC voltage interference.
window was applied in time domain data to improved the resolution. However,
window can improve the signal resolution, it will also increase the noise level in frequency domain. Therefore, newly developed noise reduction algorithm will be applied to make a balance between resolving power and S/N ratio for magnitude mode. The trace algorithm can determine the current data point with several data points (mean, past data, calculated past data). In the current calculations, we assumed data points with S/N ratio more than 3 were considered as signal data points. After the windowing and noise reduction, both resolution and signal-to-noise ratio were improved. This algorithm is applicable more efficiently to frequency dependent noise and large size data.
A Study on the Postprocessing of Channel Estimates in LTE System
Yoo, Kyung-Yul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 205~213
DOI : 10.5370/KIEE.2011.60.1.205
The Long Term Evolution (LTE) system is designed to provide a high quality data service for fast moving mobile users. It is based on the Orthogonal Frequency Division Multiplexing (OFDM) and relies its channel estimation on the training samples which are systematically built within the transmitting data. Either a preamble or a lattice type is used for the distribution of training samples and the latter suits better for the multipath fading channel environment whose channel frequency response (CFR) fluctuates rapidly with time. In the lattice-type structure, the estimation of the CFR makes use of the least squares estimate (LSE) for each pilot samples, followed by an interpolation both in time-and in frequency-domain to fill up the channel estimates for subcarriers corresponding to data samples. All interpolation schemes should rely on the pilot estimates only, and thus, their performances are bounded by the quality of pilot estimates. However, the additive noise give rise to high fluctuation on the pilot estimates, especially in a communication environment with low signal-to-noise ratio. These high fluctuations could be monitored in the alternating high values of the first forward differences (FFD) between pilot estimates. In this paper, we analyzed statistically those FFD values and propose a postprocessing algorithm to suppress high fluctuations in the noisy pilot estimates. The proposed method is based on a localized adaptive moving-average filtering. The performance of the proposed technique is verified on a multipath environment suggested on a 3GPP LTE specification. It is shown that the mean-squared error (MSE) between the actual CFR and pilot estimates could be reduced up to 68% from the noisy pilot estimates.
Thermal Performance Assessment of Wet Ondol and Electric Ondol System
Han, Byung-Jo ; Koo, Kyung-Wan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 214~220
DOI : 10.5370/KIEE.2011.60.1.214
This paper studies about the assessment of thermal performance between wet ondol system and electric ondol system. Electrical ondol systems shows faster warm-up time, higher floor surface temperature distribution and lower power consumption than wet ondol system. However, if we provide heat regularly wet ondol system which has more heat capacity shows greater thermal storage than electric ondol system. Therefore, we could conclude that wet ondol system which keeps temperature regularly by the thermal storage show better energy-efficiency in case of using the central heating and district heating system. However, Electrical ondol system shows better efficiency in case of using the space during short time or individual heating systems which needs to heat quickly. The Experiment says that electric ondol system has more benefits on timing to reach the set temperature and energy-efficiency than wet ondol system.
A Development of Transfer Robot for Container Loading/unloading Horizontally
Lee, Young-Jin ; Han, Dong-Seop ; Cho, Hyeun-Cheol ; Han, Geun-Jo ; Koo, Kyung-Wan ; Lee, Kwon-Soon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 60, issue 1, 2011, Pages 221~229
DOI : 10.5370/KIEE.2011.60.1.221
Recently, intermodal transportation systems are significantly considered as enhanced technique or future railroad logistics. These are aimed for particularly reducing complicated job process in the railroad based transportation and relevant logistic cost in economic viewpoint. In this paper we suggest a horizontal transfer system using hydro-motor and hydro-cylinder for intermodal transportation system. This system can assist to transfer the containers horizontally for train logistics automations.