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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 59, Issue 12 - Dec 2010
Volume 59, Issue 11 - Nov 2010
Volume 59, Issue 10 - Oct 2010
Volume 59, Issue 9 - Sep 2010
Volume 59, Issue 8 - Aug 2010
Volume 59, Issue 7 - Jul 2010
Volume 59, Issue 6 - Jun 2010
Volume 59, Issue 5 - May 2010
Volume 59, Issue 4 - Apr 2010
Volume 59, Issue 3 - Mar 2010
Volume 59, Issue 2 - Feb 2010
Volume 59, Issue 1 - Jan 2010
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Coordinated Control Modeling and Simulation among the Voltage Compensation Equipments Using Python
Lee, Sang-Deok ; Baek, Young-Sik ; Seo, Gyu-Seok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 1~8
The ultrafashionable machinery that require high quality electricity power has been daily come into being. Because domestic power system has been larger and more complicated in accordance with raising power demand by power market requirement. Because of these power market situations, The FACTS (Flexible AC Transmission System) which is power transmission system for the next generation to meet flexible supply the power and reliability has been applied. If they, compensators and FACTS, are used inter-efficiently in range that does not affect the stability and a badly influence the security, they might be increase in the voltage stability of system, supply reliability and also achieve the voltage control in a suddenly changed power system. Therefore we describe and suggest on this treatise that a plan for coordination control between UPFC, Shunt elements (Sh. Capacitors & Sh. Reactors) among compensators and also describe the method to keep or control the voltage of power system in allowable ranges. The method follows that, we used characteristics of each equipment, UPFC would be also settled to keep the identified voltage range in change of load bus, Shunt elements also would be settled to supply the reactive power shortage in out of operating range of UPFC to cope actively with change of the power system. As the result of simulation, it is possible to keep the load bus voltage in limited range in spite of broad load range condition. This helps greatly for the improvements of supply reliability and voltage stability.
Reliability Assessment of Railway Power System by using Tree Architecture
Cha, Jun-Min ; Ku, Bon-Hui ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 9~15
As catenary supply electric power directly to the railway system, it is very important to prevent an accident of a catenary for appropriate train operation. This paper proposed the assessment the outage data for "British Catenary Safety Analysis Report" and Korean data to compare the reliability of the railway system. The analyzed data were applied to Event Tree and Fault Tree algorithm to calculate the reliability indices of railway system. Event tree is created and gate results of fault tree analysis are used as the source of event tree probabilities. Fault tree represents the interaction of failures and basic events within a system. Event Tree and Fault Tree analysis result is helpful to assess the reliability to interpreted. The reliability indices can be used to determine the equipment to be replaced for the entire system reliability improvement.
Wind Generation Monitoring System based on International Standard IEC61400-25
Choi, Young-Jun ; Lee, Seung-Jae ; Choi, Myeon-Song ; Lee, Duck-Su ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 16~18
This paper presents monitoring system based on IEC61400-25 for 750kW-class DFIG wind power generation system. It consists of wind turbine PLC, Local and Remote I/O Server, human machine interface, and Web-server. Proposed System has been demonstrated in Daegi-ri, Kangwon-do, which aims to test IEC61400-25 communication capability of monitoring system and evaluate the performance of 750kW-class WTS.
The Advanced Protection Coordination Scheme using Phase Angle of Zero-Sequence Current in Ungrounded System
Choi, Young-Jun ; Lim, Hee-Taek ; Choi, Myeon-Song ; Lee, Seung-Jae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 19~25
Most faults are single-phase-to-ground fault in ungrounded system. The fault currents of single-phase-to-ground are much smaller than detection thresholds of measurement devices, so detecting single-phase-to-ground faults is difficult and important in ungrounded system. The protection coordination method using SGR(Selective Ground Relay) and OVGR(Overvoltage Ground Relay) is generally used in ungrounded system. But this method only detects fault line and it has the possibility of malfunction. This paper proposed to advanced protection coordination method in ungrounded system. The method just using zero-sequence current can detect fault line, fault phase, fault section at terminal device. The general protection method is used to back up protection. In the case study, the proposed method has been testified in demo system by Matlab/Simulink simulations.
Development of Methodology of New Effective Installed Reserve Rate considering Renewable Energy Generators
Park, Jeong-Je ; Choi, Jae-Seok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 26~32
This paper proposes a new effective installed reserve rate in order to evaluate reliability of power system considering renewable generators, which include uncertainty of resource supply. It is called EIRR(effective installed reserve rate) in this paper. It is developed with considering capacity credit based on ELCC by using LOLE reliability criterion. While the conventional installed reserve rate index yields over-evaluation reliability of renewable generators, the proposed EIRR describes actual effective installed reserve rate. However, it is not the probabilistic reliability index as like as LOLE or EENS but another deterministic effective reliability index. The proposed EIRR is able to evaluate the realistic contribution to the reliability level for power system considering wind turbine generators and solar cell generators with high uncertainty in resource supply. The case study in model system as like as Jeju power system size presents a possibility that the proposed EIRR can be used practically as a new deterministic reliability index for generation expansion planning or operational planning in future.
A Study on the Harmonic Current Characteristic and Emission Value Assess Method Considering the Linear Load
Park, Yong-Up ; Choi, Seung-Hoon ; Chang, Joon-Soo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 33~39
In order to operate the power system satisfactory for both system operators and customers, it is important to limit the harmonic currents to the allowable levels which injected into the system from the distorting installations. In this regard, the principles for the allocation of emission limits on individual customer were introduced in the technical report of IEC61000-3-6. According to these general principles, the emission limits are dependent on the agreed power of the customer, the power of the harmonic-generating equipment, and the system characteristics. The considerations in this report are very comprehensive and the process introduced is practical enough to implement as it is. However, there is a fact not appropriately dealing in the report that could be a very tickle but has a huge impact on determining the emission limit. This is the effect of non-harmonic load currents. More precisely, these are from the equipments which do not emit any harmonic or may emit harmonics but this specific order under the consideration by themselves if the source power is sinusoidal. The load currents originated from these equipments have an effect of active filter against the specific order of harmonic therefore, these should be dealt as a significant factoron the process of determining the emission limits for individual customer.
The Method of Calculating the Distribution Loss Factor using the Load Current Pattern
Choi, Seung-Hoon ; Kim, Joon-Eel ; Park, Yong-Up ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 40~45
In order to establish the electric distribution system economically and operate efficiently, it becomes important to calculate energy losses of the system more accurately. This importance is not only related for the engineering of utilities' power network but also for the consumers' electric system. The Distribution Loss Factor (DLF) is the fundamental element of calculating the energy losses occurred through the electric system including the electric lines and equipments. Up to now, the DLF is calculated by empirical formulas using the correlation between the DLF itself and Load Factor. However, these methods have some limitations to reflect the various characteristics of the system and the load. In this regard, the novel method proposed here is developed to yield more accurate result of DLF which actively interacting with the characteristics and load patterns of the system. The improvement of accuracy is very significant according to the results of verification presented at the end of this paper.
Economic Analysis of Jeju Island Power System Outage Using Event Study
Kim, Jin-A ; Lee, Jae-Hee ; Lee, Jong-Uk ; Joo, Sung-Kwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 46~50
Power system outages can lead to huge economic losses for various industries. Jeju island power system outage in 2006 also caused significant social and economic impacts in Korea. There have been numerous attempts to evaluate the economic costs of power system outages. Power system outages can also have financial impacts on electric power industry. This paper attempts to analyze the economic impacts of the 2006 Jeju island power system outage on the values of the firms in the power industry using event study. Empirical analysis results are presented to show the economic impacts of the 2006 Jeju island outage on the values of the firms in the power industry.
Angular Dependency of Magnetization Losses in Continuously Transposed Coated Conductors for Large Current Applications
Han, B.W. ; Kim, W.S. ; Lee, J.K. ; Lee, S.Y. ; Park, S.H. ; Kim, Y.I. ; Choi, K. ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 51~56
AC loss is main issue for power applications using YBCO coated conductor. The striated YBCO CC(Coated Conductor) has been proposed by several researchers to decrease a magnetization loss. A continuously transposed coated conductor (CTCC), suggested by our research group before, could be very useful for lower magnetization loss of large current power applications. In this paper, an AC loss reduction effect by the stack, striation and transposition of YBCO CCs under a time varying external magnetic field. To estimate the reduction effects for perpendicular magnetization loss, several CTCC samples were prepared and tested. Also, we measured angular dependency of magnetization losses of various CTCC samples.
Rotor Pole Design and Characteristics Analysis of the Bearingless Switched Reluctance Motor Considering Fringing Flux
Lee, Chan-Kyo ; Oh, Ju-Hwan ; Shin, Kwang-Chul ; Kwon, Byung-Il ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 57~64
In this paper, a novel Bearingless Switched Reluctance Motor(BLSRM) with the shoe rotor pole in order to minimize the torque ripple and the suspension force ripple at an overlap position is proposed. For reduction the torque ripple and the suspension force ripple at an overlap position, the fringing flux is used for the main flux. This configuration of the rotor pole results in more average torque with high suspension force. In addition, this paper is compared the transient characteristics using the inductance look-up table. The torque, radial force and flux density are analyzed by finite element method.
A Study on the Characteristics of Supercapacitor for High Voltage System
Kim, Byeong-Woo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 65~69
Supercapacitors as novel energy storage devices between conventional capacitors and batteries, with more specific capacitance and energy densities than conventional capacitors and more power densities than batteries are to be used in many fields. And, social demand on fuel economy and reducing pollution needs equipment of new function such as energy storage system with good power performance, high cyclability and good energy efficiency. Supercapacitor is regarded as one of good alternatives for meeting the requirement of market with excellent power performance and high cyclability. This paper deals with the fundamental characteristics of supercapacitor unit and charge and discharge behavior of supercapacitor module for developing 42V hybrid energy storage system with lead acid battery and supercapacitor in order to adopt to 42V power net for vehicle.
A New Velocity Measurement Method using Linear Type Hall-effect Sensor for Electro-mechanical Fin Actuator
Gu, Jeong-Hoi ; Song, Chi-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 70~75
The objective of this paper is to propose a new velocity measurement method for an electro-mechanical fin actuator. The model of the electro-mechanical fin actuator includes uncertainties such as unknown disturbances and parameter variations in flight condition. So, an electro-mechanical fin actuator system needs robust control algorithm which requires not only position information but also velocity information. Usually, analog tachometers have been used for velocity feedback in an electro-mechanical fin actuator. However, using these types of sensors have problems such as the cost, space, and malfunction. These problems lead to propose a new velocity measurement method using linear type Hall-effect sensor. In order to verify the proposed method, several experiments are performed using Model Following Sliding Mode Controller(MFSMC). It is shown that the MFSMC with a new velocity measurement method using linear type Hall-effect sensor can satisfy the requirements without using of velocity sensor.
Development of Integrated Simulator for AC Traction Power Supply System
Kim, Joo-Rak ; Kim, Jung-Hoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 76~81
This paper describes the development of integrated simulator with GUI(Graphic User Interface) for traction power supply system. This simulator consists of a lot of calculation modules such as TPS, train time schedule, line constant, and power supply system analysis. Each module has input and output structure respectively. The algorithms of all modules have confirmed the validity to comparison with field test that is performed on both high speed railway line and conventional line.
Development of a Measurement System for Contact Force Analysis of Trolley Line
Kim, In-Chol ; Choi, Kyu-Hyoung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 82~87
A measurement system of contact force between overhead contact line and pantograph of train is developed which measures the contact force by using four sets of full-bridge strain gauges instead of load cells and accelerometers. The sensors are installed on the pan head of pantograph and the measured data from the sensors are transmitted to a server system in the train by way of wireless Lan. This configuration of the measuring system makes it easy to install on the trains without any alteration of train system. The measurement system is applied to KTX on the Kyungbu high speed line, and the measured contact force data shows good agreement with those measured by load cell and accelerometers. The waveform of the contact force between overhead contact line and pantograph contains essential information about their conditions. The proposed measurement system can probe any defects on overhead contact lines with train running at high speed, which will be a powerful solution for the maintenance of long-distance overhead contact lines.
DCM Analysis of Interleaved Boost Converter for Fuel Cell Applications
Kim, Dong-Hee ; Choe, Gyu-Yeong ; Kim, Jong-Soo ; Lee, Byoung-Kuk ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 88~95
In this paper, the variation of phase current and input current ripple of interleaved boost converter at DCM for fuel cell applications are theoretically analyzed. Also, based on the detailed analysis, numerical formula of input current ripple expressed in rising and falling slope magnitude, D, and
is proposed. In order to verify proposed formulas, simulation and experimental results are compared with theoretical data and validity of proposed theory is established.
Connection Algorithm Proposal of Real Time Digital Simulator with Miniaturized HTS SMES
Kim, A-Rong ; Kim, Gyeong-Hun ; Kim, Kwang-Min ; Park, Min-Won ; Yu, In-Keun ; Sim, Ki-Deok ; Kim, Seok-Ho ; Seong, Ki-Chul ; Park, Young-Il ; Kim, Jin-Geun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 96~101
Superconducting Magnetic Energy Storage (SMES) system is one of the key technologies to overcome the voltage sag, swell, interruption and frequency fluctuation by fast response speed of current charge and discharge. In order to evaluate the characteristics of over mega joule class grid connected High Temperature Superconducting (HTS) SMES system, the authors proposed an algorithm by which the SMES coil could be connected to the Real Time Digital Simulator (RTDS). Using the proposed algorithm, users can perform the simulation of voltage sag and frequency stabilization with a real SMES coil in real time and easily change the capacity of SMES system as much as they need. To demonstrate the algorithm, real charge and discharge circuit and active load were manufactured and experimented. The results show that the current from real system was well amplified and applied to the current source of simulation circuit in real time.
Analyses of the Output Characteristics and the Change of Internal Impedance of Dye-sensitized Solar Cell According to the Adsorption Time
Kim, Hee-Je ; Lee, Jeong-Gee ; Seo, Hyun-Woong ; Son, Min-Kyu ; Shin, In-Young ; An, Tae-Pung ; Kim, Jin-Kyoung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 102~107
Dye-sensitized solar cell (DSC) has been expected to be an alternative to the conventional silicon solar cell due to simple manufacturing process and low fabrication casts. In order to improve productivity of DSC, we attempted to optimize the required time of the adsorption process. According to the change in the adsorption time from 1 to 24h, We analyzed the output characteristics and the change of internal impedance. As a result, The outputs of DSC were continuously increased until 12h of the adsorption time and remained the same after that. Also, We reconfirmed this result that 12h was optimum adsorption by the analysis of the electrochemical impedance spectroscope because the internal impedance was similar to the output.
Process Optimization Approached by Design of Experiment Method for Ga-doped ZnO Thin Films
Lee, Deuk-Hee ; Kim, Sang-Sig ; Lee, Sang-Yeol ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 108~112
Design of experiment (DOE) method is employed for a systematic and highly efficient optimization of Ga-doped ZnO thin films synthesized by pulsed laser deposition (PLD) process. We sequentially adopted fractional-factorial design (FD) and central composite design (CCD) of the DOE methods. In fractional-FD stage, significant factors to make conductive electrode are found to target-substrate (T-S) distance and oxygen partial pressure. Moreover, correlation among the process factors is elucidated using surface profile modeling. Electrical properties of the GZO films grown on a glass substrate had been optimized to find that the lowest electrical resistivity of about
which was acquired with the T-S distance and the oxygen pressure of 4 cm and 7 mTorr, respectively. During the DOE-fueled optimization process, the transparency of the GZO films is ensured higher than 85 %.
The characteristics of ZnO Thin film on PES substrate by pulsed laser deposition
Choi, Young-Jin ; Lee, Cheon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 113~115
In this study, ZnO films have been grown on PES(polyethersu]fone) substrate by PLD(pulsed laser deposition) and characterized as a change of laser density and substrate temperature. Growing conditions were changed with substrate temperatures ranging from 50 to
and laser densities ranging from
. Optical and structural properties were measured by XRD, SEM, AFM, PL measurement.
Design and Characterization of 3 dB Branch Type Directional Couplers using High-Tc Superconductors
Chung, Dong-Chul ; Choi, Myoung-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 116~119
In this work, we presented the characterization of 3 dB branch type directional couplers by using High-Tc superconducting thin films. To do this, we deposited YBCO superconducting thin films on MgO substrates by using rf-magnetron sputtering techniques. The designed center frequency was 408 MHz and the designed passband was 20 MHz. Also we designed 3 dB Power difference and
of phase difference between port 3 and port 4. The even and odd mode analysis were used to characterize our directional couplers and em Sonnet (full wave analysis program) was utilized to the optimum design. We reported experimental results, including a center frequency, passband, half power characteristics and phase differences. We confirmed that experimental results were in good agreements with characterization by using full wave analysis program.
Fabrication of Superconducting Thick Film by Spray Pyrolysis Method
Lee, Sang-Heon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 120~122
In this paper the effect of constituent content on superconductivity and phase in BiPbSrCaCuO system was reported. The zero resistance temperature reaches as high as 100k when dophant Sb was decreased dramatically with increasing Sb content in BiPbSrCaCuO system while the corresponding phase was changed fundamentally.
Optoelectronic Characteristics of Transparent Cu
O Films Spin-coated on Glass Substrates
Kwak, Ki-Yeol ; Cho, Kyoung-Ah ; Kim, Sang-Sig ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 123~126
nanoparticles-based films are fabricated by spin-coating on glass substrates and their optoelectronic characteristics are investigated in this study. The
films are nearly all-transparent as high as 98% in a wavelength range from 400 nm to 900 nm and three exciton peaks associated with the sublevels in the conduction band are observed at the wavelengths shorter than 400 nm in the absorption spectrum. Under the illumination of the 325 nm wavelength light, the photocurrent efficiency of the
at a voltage of 2.5 V in air.
Electrical Property and Application of Au Electrodes Passivated with DDT Molecules
Choi, Min-Su ; Lee, Dong-Jin ; Kim, Tae-Gun ; Hwang, Sung-Woo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 127~129
We report the passivation characteristics of dodecanethiol (DDT) molecules on gold electrodes of field effect transistor bio-sensors. The leakage current between the electrolyte and the electrode can be as small as 3pA when 7 mM of DDT passivation is performed. The DDT layer is also shown to resist the attack of acid up to 120 mins.
Improved Contact Characteristics in a Single Tin-Oxide Nanowire Device by a Selective Reactive Ion Etching (RIE) Process
Lee, Jun-Min ; Kim, Dae-Il ; Ha, Jeong-Sook ; Kim, Gyu-Tae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 130~133
Although many structures based on
nanowires have been demonstrated, there is a limitation towards practical application due to the unwanted contact potential between the metal electrode and the
nanowire. This is mostly due to the presence of the native oxide layer that acts as an insulator between the metal contact and the nanowire. In this study the contact properties between Ti/Au contacts and a single
nanowire was compared to the electrical properties of a contact without the oxide layer. RIE(Reactive Ion Etching) is used to selectively remove the oxide layer from the contact area. The
nanowires were synthesized by chemical vapor deposition (CVD) and dispersed on a
substrate. The Ti/Au (20nm/100nm) electrodes were formed bye-beam lithography, e-beam evaporation and a lift-off process.
A Design of an LED Sensor Luminaire for Visual Function Improvement
Seo, Jung-Nam ; Yu, Yong-Su ; Yeo, In-Seon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 134~137
An LED sensor luminaire for visual function improvement necessitates the control algorithm for light level adjustment and the appropriate lens design. The control algorithm adapts to surround lighting condition, and thus has the advantages of energy saving and glare reduction. The multi-cell lens design improves color temperature uniformity and spatial light distribution of the luminaire. Experimental and simulated results show that this approach contributes noticeably to energy saving and color temperature uniformity of the LED sensor luminaire.
A Micro Passive Gas Pressure Regulator using Pressure Balance Mechanism
Lee, Ki-Jung ; Yang, Sang-Sik ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 138~143
This paper presents the analysis, the fabrication and the test results of a micro passive gas pressure regulator to keep the outlet pressure costant even for a widely-varying inlet pressure. This device is to regulate the outlet pressure according to the applied reference pressure based on the pressure balancing mechanism of the structure including a membrane and a valve. This regulator consists of four layers; a bulk-micromachined silicon substrate, a sandblasted glass substrate, a PDMS valve seat layer and a glass valve layer. The device size is
. The device was fabricated by micromachining. The characteristic of the device was analyzed and tested. The characteristic of the fabricated pressure regulator is similar to that obtained from the analysis. The pressure regulator of this paper is feasible for portable systems and miniature drug delivery systems.
A Characteristic Study on the Dye-Sensitized Solar Cell by the Shadow Effect
Kim, Hee-Je ; Lee, Jeong-Gee ; Lee, Kyung-Jun ; Prabakar, Prabakar ; Sin, Dong-Seoul ; Chae, Won-Yong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 144~151
The shadowing effects lead to the serious power losses of the PV module. The shadowing effects are caused by several factors such as leafs, dust, antenna and clouds. The dye-sensitized solar cells are more economical than the conventional silicon solar cell that's why the dye-sensitized solar cells are recently focused on. We carried out research on the efficiency of the dye-sensitized solar cell depending on the level of shadow changing the formula of the circuit. The research on the efficiency of the large dye-sensitized solar cell depending on the level of shadow focused on commercialization was carried out. As the results, it is known that the series and parallel connection method is the best choice for the least losses of PV module assemblies. It is especially known that one more series connection is the best choice for the least losses about shadowing effects and current losses in the series and parallel connection.
The Minimization of Generator Output Variations by Impulse Chamber Pressure Control during Turbine Valve Test
Choi, In-Kyu ; Kim, Jong-An ; Park, Doo-Yong ; Woo, Joo-Hee ; Shin, Jae-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 152~159
This paper describes the actual application of a feedback control loop as a means for minimizing turbine impulse chamber pressure variation during the turbine steam valve tests at a 1,000 MW nuclear power plant. The chamber pressure control loop was implemented in the new digital control system which was installed as a replacement for the old analog type control system. There has been about 40MW of the generator output change during the steam valve tests, especially the high pressure governing valve tests, because the old control system had not the impulse chamber pressure control so the operators had to compensate steam flow drop manually. The process of each valve test consists of a closing process and an reopening process and the operators can make sure that the valves are in their sound conditions by checking the valves movement. The control algorithm described in this paper contributed to keep the change in megawatt only to 6MW during the steam valve tests. Thereby, the disturbance to reactor control was reduced, and the overall plant control system's stability was greatly improved as well.
Enhancement of the Speed Response of PMSM Sensorless Control Using A New Adaptive Sliding Mode Observer
Kim, Hong-Ryel ; Son, Ju-Beom ; Lee, Jang-Myung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 160~167
This paper proposes an adaptive sliding mode observer (SMO), which adds the estimation function of the stator resistance to a new sliding mode observer for the robust sensorless control of permanent magnet synchronous motor (PMSM) with variable parameters. To reduce the chattering problem commonly found in the conventional sliding mode observer where the low-pass filter and additional position compensation of the rotor are used, the sigmoid function is used for the control of a switching function in this research. With the estimation of the stator resistance, the proposed observer can improve the control performance by reducing the estimation error of the motor's speed. Note that the stator resistance is varying with the ambient temperature and becomes an error source for the sensorless control of PMSM. The new sliding mode observer has better efficiency than the conventional adaptive sliding mode observer by reducing the time consuming integral calculations. The stability of the proposed adaptive sliding mode observer is verified by the Lyapunov function in determining the observer gains, and the effectiveness of the observer is demonstrated by simulations and experiments.
Periodic Disturbance Cancellation by using Dual-Input Describing Function (DIDF) Method
Choe, Yeon-Wook ; Lee, Hyung-Ki ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 168~175
The issue of rejecting periodic disturbances arises in various applications dealing with rotating machinery. A new method using DIDF (Dual-Input Describing Function) is presented for the rejection of periodic disturbances with uncertain frequency. This can be added to an existing feedback control system without altering the closed-loop system stability. The objective is to design a nonlinear compensator to secure specified oscillation amplitude and frequency which are the same as disturbances. We suggest two procedures to determine coefficients for DIDF's synthesis. The structure of the proposed DIDF is so simple that we can easily synthesize. A number of computer simulations were carried out to demonstrate the salient feature of the proposed DIDF compared to the conventional ones(that is, adaptive algorithms).
Practical Design Issues in a Linear Feedback Control System with a Notch Filter
Jin, Lihua ; Kim, Young-Chol ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 176~183
This paper presents some practical design issues that should be carefully considered when a notch filter is included in a linear feedback controller. A notch filter is generally used to compensate the effects of resonant modes that may result in poor performance. It is very common that the practical engineers prefer to add such a notch filter after having previously designed a feedback controller without the filter. It is known that the resulting performance by this approach is not seriously different from when a feedback controller is designed for a plant previously compensated by a notch filter. However, we will point out that there are some cases where both approaches have different performances. In order to show this, a low-order controller design using the partial model matching method has been applied to a linear time invariant (L Tn model. The results suggest that there is a tendency to achieve much better time responses in terms of reducing the overshoot and shortening the settling time, and in the frequency domain characteristics such as the sensitivity function and the stability margins when the design of a feedback controller after including a notch filter is carried out.
Design of Fuzzy Prediction System based on Dual Tuning using Enhanced Genetic Algorithms
Bang, Young-Keun ; Lee, Chul-Heui ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 184~191
Many researchers have been considering genetic algorithms to system optimization problems. Especially, real-coded genetic algorithms are very effective techniques because they are simpler in coding procedures than binary-coded genetic algorithms and can reduce extra works that increase the length of chromosome for wide search space. Thus, this paper presents a fuzzy system design technique to improve the performance of the fuzzy system. The proposed system consists of two procedures. The primary tuning procedure coarsely tunes fuzzy sets of the system using the k-means clustering algorithm of which the structure is very simple, and then the secondary tuning procedure finely tunes the fuzzy sets using enhanced real-coded genetic algorithms based on the primary procedure. In addition, this paper constructs multiple fuzzy systems using a data preprocessing procedure which is contrived for reflecting various characteristics of nonlinear data. Finally, the proposed fuzzy system is applied to the field of time series prediction and the effectiveness of the proposed techniques are verified by simulations of typical time series examples.
System Design of High-Definition Media Transceiver based on Power Line Communication and Its Performance Analysis
Kim, Ji-Hyoung ; Kim, Kwan-Woong ; Kim, Yong-K. ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 192~196
Due to a development of a modem technology as Power Line Communication(PLC) over 200 Mbps, the high-speed multi-media data trasmission could be currently possible. The strength of the PLC has no more additional wiring work. PLC has also possible to high quality data transmission with currently electrical cable. It has a various strong point campare with existing wire and wireless communication technologies. In This paper we develop a high quality media transmitter-receiver based on merging the HomePlug AV, which is 200 Mbps class PLC technology and HDMI Interface technology. The video function was used for the VEDEO TEST GENERATOR in order to a property valuation. Smart Live 6 software were used for the assessment of audio property. As the result of measurement of the HD class images by capturing from the receiver of the PLC, the quality of images couldn't be confirm any deterioration, which has compared with original reflections. In case of audio part as the result of confirmation of the Phase, Magnitude, it has been confirmed that over 90% of nomal transmition and receiving of acoustic signal. It can be possible to have HD class Media service through the PLC.
ELS: An Efficient Localization Scheme based on GPS for Ubiquitous Sensor Network
Yun, Jae-Keun ; Ko, Du-Hyun ; Kim, Bum-Jin ; Ahn, Sun-Shin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 197~203
The problem of location awareness in wireless sensor networks where nodes use GPS (Global Positioning System), remains challenging problem, when considering the required large energy consumption during the localization phase. In this paper we designed hardware for GPS based localization and propose a framework, called ELS, to consume low cost energy. In the ELS framework, sensor nodes are equipped with GPS. Because GPS spends large energy for position awareness, conventional localization algorithms cannot use GPS-device. We try to find a solution for efficient energy expenditure of GPS. Finally, we derive optimal transmission power of GPS data and a scheme of localization through experiment and simulation.
Research of Short Preamble MAC Protocol for Energy Efficient in Wireless Sensor Network
Na, Kyeng-Heum ; Lee, Sang-Bin ; Ko, Doo-Hyun ; An, Sun-Shin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 204~209
Idle listening is very critical source of energy dissipation in wireless sensor networks. To reduce idle listening, we propose preamble sampling MAC that is named EESP-MAC. The main idea of EESP-MAC is to add control information into the short preamble frame. So the stream of short preambles is used not only for preamble sampling but also for avoiding overhearing, decreasing control packet overhead and reducing the listening of the redundant message, caused by message-flooding.
Individual Tooth Image Segmentation by Watershed Algorithm
Lee, Seong-Taek ; Kim, Kyeong-Seop ; Yoon, Tae-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 210~216
In this study, we propose a novel method to segment an individual tooth region in a true color image. The difference of the intensity in RGB is initially extracted and subsequent morphological reconstruction is applied to minimize the spurious segmentation regions. Multiple seeds in the tooth regions are chosen by searching regional minima and a Sobel-mask edge operations is performed to apply MCWA(Marker-Controlled Watershed Algorithm). As the results of applying MCWA transform for our proposed tooth segmentation algorithm, the individual tooth region can be resolved in a CCD tooth color image.
Clinical Effectiveness of New Portable System for Measuring Spasticity of the Stroke Patients
Kim, Keo-Sik ; Seo, Jeong-Hwan ; Song, Chul-Gyu ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 217~219
Spasticity is a motor disorder characterized by a velocity dependent increase in muscle tone with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflex. The aim of this study is to develop a portable system for quantifying the grade of spasticity which could calculate the biomechanical as well as neurophysiologic parameters, and for determining the relationship between the Tonic Stretch Reflex Threshold (TSRT) and Modified Ashworth Scale (MAS). Eleven patients with stroke participated in the study (6 males and 5 females, the average age of
years). As a results, the mean and standard deviation values of the TSRT were
in the MAS 1, MAS 1+ and MAS 2 groups, respectively. Also, there was a negative correlation between the TSRT and MAS (rho=-0.72, p<0.05). This demonstrated that the TSRT could be made clinically available for the more objective and reliable evaluation of the spasticity, instead of using the conventional clinical scales and an isokinetic dynamometer.
Correct Posture Guidance System using 3-axis Acceleration Sensor for Scoliosis Patient
An, Yang-Soo ; Kim, Keo-Sik ; Seo, Jeong-Hwan ; Song, Chul-Gyu ;
The Transactions of The Korean Institute of Electrical Engineers, volume 59, issue 1, 2010, Pages 220~224
In this study, we designed a device for consecutively observing position, utilizing 3-axises acceleration sensor. This method offer to check his or her wrong position and developed could to help derived a position appliance. And, we developed a Cobb's angle value in three dimensional using 3-axises acceleration sensor. A proposed device with integrated accelerometers, which can detect postural changes in terms of curvature variation of the spine in the sagittal and coronal planes, has been developed with intention to facilitate posture training. The proposed device was evaluated with 3 normal subjects daily activities. We evaluated the performance of our designed device as calculating the correlation coefficients and mean errors between the angle measured by an electro-goniometer and that estimated by a gravity accelerometer and verified the accuracy and sensitivity. The results showed that the angle obtained from the proposed device revealed a linear characteristic at the range of
(correlation coefficient 0.99, error range
). We demonstrated that our device could detect the changes of the motion in upper trunk accurately. Also, our device showed good potential for treatment of the patients with scoliosis and prevention of the unbalance position during a daily life.