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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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Journal DOI :
The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 61, Issue 12 - Dec 2012
Volume 61, Issue 11 - Nov 2012
Volume 61, Issue 10 - Oct 2012
Volume 61, Issue 9 - Sep 2012
Volume 61, Issue 8 - Aug 2012
Volume 61, Issue 7 - Jul 2012
Volume 61, Issue 6 - Jun 2012
Volume 61, Issue 5 - May 2012
Volume 61, Issue 4 - Apr 2012
Volume 61, Issue 3 - Mar 2012
Volume 61, Issue 2 - Feb 2012
Volume 61, Issue 1 - Jan 2012
Selecting the target year
Short-Term Load Forecast for Near Consecutive Holidays Having The Mixed Load Profile Characteristics of Weekdays and Weekends
Park, Jeong-Do ; Song, Kyung-Bin ; Lim, Hyeong-Woo ; Park, Hae-Soo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1765~1773
DOI : 10.5370/KIEE.2012.61.12.1765
The accuracy of load forecast is very important from the viewpoint of economical power system operation. In general, the weekdays` load demand pattern has the continuous time series characteristics. Therefore, the conventional methods expose stable performance for weekdays. In case of special days or weekends, the load demand pattern has the discontinuous time series characteristics, so forecasting error is relatively high. Especially, weekdays near the thanksgiving day and lunar new year`s day have the mixed load profile characteristics of both weekdays and weekends. Therefore, it is difficult to forecast these days by using the existing algorithms. In this study, a new load forecasting method is proposed in order to enhance the accuracy of the forecast result considering the characteristics of weekdays and weekends. The proposed method was tested with these days during last decades, which shows that the suggested method considerably improves the accuracy of the load forecast results.
Benefit-Cost Analysis in Accordance with Replacement of Electrical Cooling System by Gas Cooling System using the California Standard Test
Park, Rae-Jun ; Song, Kyung-Bin ; Won, Jong-Ryul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1774~1781
DOI : 10.5370/KIEE.2012.61.12.1774
There are some efforts to improve the performance of electrical heat pump(EHP) and replace it with an alternative cooling equipment such as gas engine-driven heat pump(GHP), a gas cooling equipment, in order to solve the problem of summer electricity supply through reducing the summer electricity peak. This paper analyzes cost-benefit in accordance with replacement of electrical cooling system by gas cooling system using california standard test and sensitivity analysis of some scenarios.
A Study on a Methodology of Determining an Appropriate Load Power Factor Effectively by the Use of Reactive Power Sensitivity and Load Duration Curve
Lee, Byung Ha ; Hwang, Sung-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1782~1790
DOI : 10.5370/KIEE.2012.61.12.1782
In this paper, a methodology to use load duration curve and the reactive power factor sensitivity of generation cost is proposed for analyzing the effects of load power factor effectively. A great deal of cases of power systems are classified into several patterns according to the characteristics using load duration curve, and the overall effects of load power factor are assessed by integrating the analysis results of load power factor in all the patterns. The reactive power sensitivity of generation cost and the integrated costs such as generation cost, investment cost, voltage variation penalty cost and CO2 emission cost are used for determining an appropriate load power factor. A systematic procedure for effective analysis of load power factor is presented. It is shown through the application to the practical power system of KEPCO(Korea Electric Power Corporation)that the effects of load power factor can be analyzed effectively using load duration curve and reactive power factor sensitivity.
Rule-based Coordination Algorithms for Improving Energy Efficiency of PV-Battery Hybrid System
Yoo, Cheol-Hee ; Chung, Il-Yop ; Hong, Sung-Soo ; Jang, Byung-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1791~1800
DOI : 10.5370/KIEE.2012.61.12.1791
This paper presents effective design schemes for a photovoltaic (PV) and battery hybrid system that includes state-of-the-art technologies such as maximum power point tracking scheme for PV arrays, an effective charging/discharging circuit for batteries, and grid-interfacing power inverters. Compared to commonly-used PV systems, the proposed configuration has more flexibility and autonomy in controlling individual components of the PV-battery hybrid system. This paper also proposes an intelligent coordination scheme for the components of the PV-battery hybrid system to improve the efficiency of renewable energy resources and peak-load management. The proposed algorithm is based on a rule-based expert system that has excellent capability to optimize multi-objective functions. The proposed configuration and algorithms are investigated via switching-level simulation studies of the PV-battery hybrid system.
Discrimination Method of Internal and External Fault of Current Differential Relay using Instantaneous Value of Current in Case of Fault with One end CT Saturation
Lee, Myoung-Hee ; Choi, Hae-Sul ; Kim, Chul-Hwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1801~1806
DOI : 10.5370/KIEE.2012.61.12.1801
This paper presents a simple and practical method which enables to prevent malfunction of protection relay due to differential current caused by one end CT saturation in case of external fault. This method uses difference of magnitude(instantaneous value) between the both end current just before the occurrence of differential current without a separate method to CT staturation detection. One end CT saturation is simulated by current transformer model using type-96 component and the presented method is verified by using EMTP MODELS with respect to internal and external fault with one end CT staturation. The presented method distinguished rightly bewteen external and internal fault with one end CT saturation. This information can be used to prevent malfunction of current differential protection relay in case of external fault. And this method is not affected by sampling rate and has no calculation burden, so it will be applicable to differential current protection relay with ease.
The Inductance Computation of IPMSM using Current Vector Control Test
Cho, Gyu-Won ; Lee, Jung-Gyu ; Kim, Gyu-Tak ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1807~1812
DOI : 10.5370/KIEE.2012.61.12.1807
In this paper, the d, q-axis inductance of IPMSM(Interior Permanent Magnet Synchronous Motor) was calculated by the FEA(Finite Element Analysis). And the CVCT(Current Vector Control Test) was performed, and compared with FEA. Therefore the inductance experiment according to the variation of the current phase angle was performed. However, the error was generated in the fundamental wave detection of the voltage and current waveform. So, error has largely effect on the result of computation, it has to note specially. In addition, by using the calculated inductance, the torque calculation was performed and this result was compared through the dynamometer experiment.
Iron Loss Analysis of Electric Machine Considering Vector Magnetic Properties of Electrical Steel Sheet
Yoon, Heesung ; Koh, Chang Seop ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1813~1819
DOI : 10.5370/KIEE.2012.61.12.1813
This paper presents vector magnetic properties of an electrical steel sheet (ESS) employed for electric machine and iron loss analysis considering the vector magnetic properties of the ESS. The vector magnetic properties of the ESS are measured by using a two-dimensional single sheet tester and modeled by an E&S vector hysteresis model to be applied to finite element method. The finite element analysis considering the vector magnetic properties is applied to iron loss analysis of a three-phase induction motor model, and the influences of the vector magnetic properties on the iron loss distribution are verified by comparing with numerical results from a typical B-H curve model.
Cogging Torque Reduction in AFPM Generator Design for Small Wind Turbines
Chung, Dae-Won ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1820~1827
DOI : 10.5370/KIEE.2012.61.12.1820
This paper is to present a new method of cogging torque reduction for axial flux PM machines of multiple rotor surface mounted magnets. In order to start softly and to run a power generator even the case of weak wind power, reduction of cogging torque is one of the most important issues for a small wind turbine, Cogging torque is an inherent characteristic of PM machines and is caused by the geometry shape of the machine. Several methods have been already applied for reducing the cogging torque of conventional radial flux PM machines. Even though some of these techniques can be also applied to axial flux machines, manufacturing cost is especially higher due to the unique construction of the axial flux machine stator. Consequently, a simpler and low cost method is proposed to apply on axial flux PM machines. This new method is actually applied to a generator of 1.0kW, 16-poles axial flux surface magnet disc type machine with double-rotor-single-stator for small wind turbine. Design optimization of the adjacent magnet pole-arc which results in minimum cogging torque as well as assessment of the effect on the maximum available torque using 3D Finite Element Analysis (FEA) is investigated in this design. Although the design improvement is intended for small wind turbines, it is also applicable to larger wind turbines.
Novel Cylindrical Magnetic Levitation Stage for Rotation as well as Translation along Axles with High Precisions
Jeon, Jeong-Woo ; Caraiani, Mitica ; Lee, Chang-Lin ; Jeong, Yeon-Ho ; Kim, Jong-Moon ; Oh, Hyeon-Seok ; Kim, Sungshin ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1828~1835
DOI : 10.5370/KIEE.2012.61.12.1828
In this paper, a conceptual design and a detailed design of novel cylindrical magnetic levitation stage is introduced. This is came from planar-typed magnetic levitation stage. The proposed stage is composed of cylinder-typed permanent magnet array and semi-cylinder-typed 3 phase winding module. When a proper current is induced at winding module, a magnetic levitation force between the permanent magnet array and winding module is generated. The proposed stage can precisely move the cylinder to rotations and translations as well as levitations with the magnetic levitation force. This advantage is useful to make a nano patterning on the surface of cylindrical specimen by using electron beam lithography under vacuum. Two methods are used to calculate required magnetic levitation forces. The one is 2D FEM analysis, the other is mathematical modeling. This paper shown that results of two methods are similar. An assistant plate is introduced to reduce required currents of winding module for levitations in vacuum. The mathematical model of cylindrical magnetic levitation stage is used for dynamic simulation of magnetic levitations. A lead-lag compensator is used for control of the model. Simulation results shown that the detail designed model of the cylindrical magnetic levitation stage with the assistant plate can be controlled very well.
Inductance Calculation in a Switched Reluctance Motor using Permeance Method
Lee, Cheewoo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1836~1842
DOI : 10.5370/KIEE.2012.61.12.1836
Torque is proportional to the rate of change of inductance in a switched reluctance motor (SRM), and hence, phase inductance is an important parameter in determining the behavior of an SRM. Therefore, the accurate prediction of inductance with respect to rotor position makes a significant contribution to designing an SRM and its analytical approach is not straightforward due to nonlinear flux distribution. Although several different approaches using a finite element analysis (FEA) or curve-fitting tool have been employed to compute phase inductance [2-5], they are not suitable for a simple design procedure because the FEA necessitates a large amount of time in both modeling and solving with complexity for every motor design, and the curve-fitting requires the data of flux linkage from either an experimental test or an FEA simulation. In this paper, phase inductance is predicted by means of a permeance method, and the proposed approach is analytically verified in terms of the accuracy of estimated inductance compared to inductance obtained by FEA.
Study on High-Efficiency Driving of a Piezo Device Using Voltage Inversion Circuit
Park, Han-Bin ; Park, Jin-Ho ; Hong, Sun-Ki ; Kang, Taesam ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1843~1847
DOI : 10.5370/KIEE.2012.61.12.1843
Piezo devices have large power density and simple structure. They can generate larger force than the conventional actuators. It has also wide bandwidth with fast response in a compact size. Thus the piezo devices are expected to be used widely in the future for small actuators with fast response time and large actuating force. However, the piezo actuators need high voltage with high driving current due to their large capacitive property. In this paper, we propose a simple method to drive piezo devices using voltage inversion circuit with coil inductance. Experiments with real circuit demonstrates that the proposed scheme can improve the energy efficiency very much.
Grid-tied Power Conditioning System for Battery Energy Storage Composed of 2-stage DC-DC converter
Park, Ah-Ryeon ; Kim, Do-Hyun ; Kim, Kyeong-Tae ; Han, Byung-Moon ; Lee, Jun-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1848~1856
DOI : 10.5370/KIEE.2012.61.12.1848
This paper proposes a new grid-tied power conditioning system for battery energy storage, which is composed of a 2-stage DC-DC converter and a PWM inverter. The 2-stage DC-DC converter is composed of an LLC resonant converter connected in cascade with a 2-quadrant hybrid-switching chopper. The LLC resonant converter operates in constant duty ratio, while the 2-quadrant hybrid-switching chopper operates in variable duty ratio for voltage regulation. The operation of proposed system was verified through theoretical analysis and computer simulations. Based on computer simulations, a hardware prototype was built and tested to confirm the technical feasibility of proposed system. The proposed system could have relatively higher efficiency and smaller size than the existing system.
Realization of Unified Protocol of Multi-functional Controller for Transfer of Vehicle Information on the Roads
Ahn, Seung-Yong ; Lim, Sung-Kyu ; Lee, Seung-Yo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1857~1863
DOI : 10.5370/KIEE.2012.61.12.1857
The VDS(Vehicle Detection System) collects and transfers information about traffic situations in real time, therefore it makes the traffic management effective. Recently, the VDSs have provided good stability and accuracy in regard to system reliability and functions but they also have showed problems such as raising costs and consuming times when a new system is installed and/or the environmental requirements for the system are set up. The reason of the problems is that up to now the collection of the data and information about the traffic situations has been achieved by the 1:1 information exchange between the traffic control surveillance center and the each traffic field, between equipments and centers, and among data processing equipments and also centers. The communication systems used in the VDS are generally composed of 1 : 1 connection of the lines because the communication protocols are different in the most of the cases mentioned above. Consequently, this makes the number of communication lines become larger and causes the cost for the whole traffic information systems to increase. In this paper, a development of a controller to unify the communication protocols for the VDS is peformed to solve the problems which were mentioned above. Specially, the controller developed in this paper was applied to a radar vehicle detector and tested to show its usefulness. In addition to that, the developed controller was also designed to include functions to transfer the information about weather conditions on the roads.
MPPT Control of Photovoltaic System using HBPI Controller
Ko, Jae Sub ; Chung, Dong-Hwa ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1864~1871
DOI : 10.5370/KIEE.2012.61.12.1864
This paper proposes the hybrid proportional integral(HBPI) controller for maximum power point tracking(MPPT) control of photovoltaic system. The output characteristics of the solar cell are a nonlinear and affected by a temperature, the solar radiation and influence of a shadow. The MPPT control is a very important technique in order to increase an output and efficiency of the photovoltaic system. The conventional constant voltage(CV), perturbation and observation(PO) and incremental conductance(IC) are the method which finding maximum power point(MPP) by the continued self-excitation vibration, and uses the fixed step size. If the fixed step size is a large, the tracking speed of maximum power point is faster, but the tracking accuracy in the steady state is decreased. On the contrary, when the fixed step size is a small, the tracking accuracy is increased and the tracking speed is slower. Therefore, in order to solve these problems, this paper proposes HBPI controller that is adjusted gain of conventional PI control using fuzzy control, and the maximum power point tracks using this controller. The validity of the controller proposed in this paper proves through the results of the comparisons.
The Calculation Method of the Breakdown Voltage for the Drain Region with the Cylindrical Structure in LDMOS
Lee, Un Gu ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1872~1876
DOI : 10.5370/KIEE.2012.61.12.1872
A calculation method of the breakdown voltage for the drain region with the cylindrical structure in LDMOS is proposed. The depletion region of the drain is divided into many smaller regions and the doping concentration of each split region is assumed to be uniformly distributed. The field and potential in each split region is calculated by the integration of the Poisson equation and the ionization integral method is used to compute the breakdown voltage. The breakdown voltage resulted from the proposed method shows the maximum relative error of 2.2% compared with the result of the 2-dimensional device simulation using BANDIS.
Dielectric Heating using High Voltage Generation of Self LC Resonance of Transformer
Jeong, Jae-Hoon ; Kim, Hee-Je ; Kim, Soo-Won ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1877~1879
DOI : 10.5370/KIEE.2012.61.12.1877
Generally, stray capacitance is unnecessary element of designing circuit, because it can not be predicted by a designer. But we propose LC Resonant Circuit using stray capacitance of transformer. This method proposes miniaturization of circuit, because LC Resonant Circuit can be make simply to using stray capacitance instead of capacitor and size of transformer is reduced. Finally, we research aspect of dielectric heating by change of frequency and output voltage using developed converter.
Monte Carlo Simulation of Thermionic Low Pressure Discharge Plasma
Koh, Wook Hee ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1880~1885
DOI : 10.5370/KIEE.2012.61.12.1880
Nonlinear dynamical behaviors in thermionic low pressure discharge are investigated using a particle-in-cell(PIC) simulation. An electrostatic PIC code is developed to model the plasma discharge system including the kinetic effects. The elastic collision, excitation collision, ionization collision, and electron-ion recombination collision are considered in this code. The generated electrons and ions are traced to analyze physical characteristics of the plasma. The simulation results show that the nonlinear oscillation structures are observed for cold plasma in the system and the similar structures are observed for warm plasma with a shift in values of the bifurcation parameter. The detailed oscillation process can be subdivided into three distinct mode; anode-glow, temperature-limited, and double-layer modes.
Electro-thermal Feedback Effects on the Signal in a Pulse Voltage Biased μ-bolometer Focal Plane Array
Park, Seung-Man ; Han, Seungoh ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1886~1891
DOI : 10.5370/KIEE.2012.61.12.1886
In this paper, the analytical models for the electrothermal feedback of a
-bolometer focal plane array(FPA) are proposed and applied to the conceptually designed FPA to investigate the electrothermal feedback effect on bolometer FPA signal. The temperature and resistance change of the
-bolometer by the electrothermal feedback(ETF) model are increased upto 20 and 35.7 % of those of no feedback case, respectively, while those by the effective thermal conductance(ETC) model increased 8.5 and 15.1 %. The integration current and output voltage of a CTIA used as an column amplifier of FPA are also increased upto 41.6 and 32.4 % by the ETF model, while increased upto 17.2 and 13.5 % by the ETC model. The proposed models give more accurate temperature change, accordingly larger signal than no feedback considering case. Electrothermal feedback effect should be considered to design a high performance and high density
-bolometer FPA. The proposed models are very useful to investigate the transient thermal analysis, also considered to be useful to predict the responsivity and dynamic range of
The Susceptibility of Electronic Circuits inside the Cavity by HPEM(High Power Electromagnetics) Environment
Hwang, Sunl-Mook ; Kwon, Hae-Ok ; Huh, Chang-Su ; Choi, Jin-Soo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1892~1897
DOI : 10.5370/KIEE.2012.61.12.1892
Modern electronic circuits are of importance for the function of communication, traffic systems and security systems. An intentional threat to these systems could be of big casualties and economic disasters. This study has examined susceptibility of electronic circuits inside the cavity by HPEM(High Power Electromagnetics). The UWB measurements were done at an anechoic chamber using a RADAN voltage source, which can generate a transient impulse of about 200 kV. The HPEM wave penetrated inside the metal case appeared to the long damped ringwave of pulse length compared with the incident wave. In addition, the resonant frequency generated inside the metal case occurred primarily in the range of 1~3 GHz. The frequency band of 1~3 GHz was influenced on the electronic circuit, which was confirmed by an external antenna and an internal absorber. The electronic circuit was influenced by HPEM infiltrated into the cavity at the 86 kV/m out of the metal cases. Also in case of an absorber the susceptibility of an electronic circuit was smallest among other cases(aperture, antenna). It is considered that absorber has a function absorbing electromagnetic wave infiltrated into the cavity and simultaneously limiting resonance by varying a boundary condition inside the cavity. Based on the results, electronic equipment systems could be applied to protection that has suited system requirements.
Robust Stability for Discrete-time Polytopic Uncertain Delay Systems with Quantization/overflow Nonlinearities
Kim, Jong-Hae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1898~1902
DOI : 10.5370/KIEE.2012.61.12.1898
In this paper, we consider the delay-dependent robust stability condition for polytopic uncertain systems with interval time-varying delay using various combinations of quantization and overflow nonlinearities. A robust stability condition for uncertain systems with time-varying delay and quantization/overflow nonlinearities is proposed by LMI(linear matrix inequality) and Lyapunov technique. It is shown that the proposed method is less conservative compared to the recent results by numerical examples.
Data Based Lower-Order Controller Design: Moment Matching Approach
Kim, Young Chol ; Jin, Lihua ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1903~1910
DOI : 10.5370/KIEE.2012.61.12.1903
This paper presents a data based low-order controller design algorithm for a linear time-invariant process with a time delay. The algorithm is composed by combining an identification step based on open loop pulse test with a low-order controller design step to obtain the entire set of controllers achieving multiple performance specifications. The initial information necessary for this algorithm are merely the width and amplitude of a rectangular pulse, a controller of four types (PI, PD, PID, first-order), and design objectives. Various parametric approaches that have been developed are merged in the controller design algorithm. The resulting controller set satisfying the design objectives are displayed on the 2D and 3D graphics and thus it is very easy for us to pick a controller inside the admissible set because we can check the corresponding closed-loop performances visually.
Optimal Path Planning in Redundant Sealing Robots
Sung, Young Whee ; Chu, Baeksuk ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1911~1919
DOI : 10.5370/KIEE.2012.61.12.1911
In this paper, we focus on a robotic sealing process in which three robots are used. Each robot can be considered as a 7 axis redundant robot of which the first joint is prismatic and the last 6 joints are revolute. In the factory floor, robot path planning is not a simple problem and is not automated. They need experienced operators who can operate robots by teaching and playing back fashion. However, the robotic sealing process is well organized so the relative positions and orientations of the objects in the floor and robot paths are all pre-determined. Therefore by adopting robotic theory, we can optimally plan robot pathes without using teaching. In this paper, we analyze the sealing robot by using redundant manipulator theory and propose three different methods for path planning. For sealing paths outside of a car body, we propose two methods. The first one is resolving redundancy by using pseudo-inverse of Jacobian and the second one is by using weighted pseudo-inverse of Jacobian. The former is optimal in the sense of energy and the latter is optimal in the sense of manipulability. For sealing paths inside of a car body, we must consider collision avoidance so we propose a performance index for that purpose and a method for optimizing that performance index. We show by simulation that the proposed method can avoid collision with faithfully following the given end effector path.
Speech Enhancement Based on IMCRA Incorporating noise classification algorithm
Song, Ji-Hyun ; Park, Gyu-Seok ; An, Hong-Sub ; Lee, Sang-Min ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1920~1925
DOI : 10.5370/KIEE.2012.61.12.1920
In this paper, we propose a novel method to improve the performance of the improved minima controlled recursive averaging (IMCRA) in non-stationary noisy environment. The conventional IMCRA algorithm efficiently estimate the noise power by averaging past spectral power values based on a smoothing parameter that is adjusted by the signal presence probability in frequency subbands. Since the minimum of smoothing parameter is defined as 0.85, it is difficult to obtain the robust estimates of the noise power in non-stationary noisy environments that is rapidly changed the spectral characteristics such as babble noise. For this reason, we proposed the modified IMCRA, which adaptively estimate and updata the noise power according to the noise type classified by the Gaussian mixture model (GMM). The performances of the proposed method are evaluated by perceptual evaluation of speech quality (PESQ) and composite measure under various environments and better results compared with the conventional method are obtained.
Fast Correction of Nonuniform Illumination on Bi-level Images using Block Based Intensity Normalization
Joung, Ji-Hye ; Kim, Jeong-Tae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1926~1931
DOI : 10.5370/KIEE.2012.61.12.1926
We investigated a novel fast non-uniform illumination correction method for bi-level images. The proposed method divides a bi-level image into sub-images and roughly estimates block-wise illumination by low pass filtered maximum values of sub-images. After that, we apply bilinear interpolation using the block-wise illumination to estimate non-uniform illumination, and compensate for the effect of non-uniform illumination using the estimated illumination. Since the proposed method is not based on computation intensive iterative optimization, the proposed method can be used effectively for applications that require fast correction of non-uniform illumination. In simulations, the proposed method showed more than 20 times faster speed than existing entropy minimization method. Moreover, in simulations and experiments, the restored images by the proposed method were more close to true images than images restored by conventional method.
Development and Verification of a Hand-held Typed Monitoring System for Cardiac Output Measurement using Electrical Impedance Technique
Seo, Kwang-Seok ; Sim, Myeong-Heon ; Kim, Min-Yong ; Yoon, Chan-Sol ; Chung, Joo-Hong ; Park, Sung-Bin ; Yoon, Hyung-Ro ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1932~1938
DOI : 10.5370/KIEE.2012.61.12.1932
The impedance cardiogram has been proposed as a non-invasive, continuous, operator independent, and cost-effective method for cardiac output monitoring. However, it can not be completely considered as non-restrictive method because of attached spot and band type electrodes. Therefore, we developed a improved convenient hand-held typed measurement system for cardiac output by electrical impedance technique. 80 subjects from Yonsei University and the surrounding areas, participated. All subjects measured stroke volume and cardiac output through Physioflow and developed system. To verify the developed system, statistical methods such as correlation, Wilcoxon signed ranks test, and the Bland-Altman analysis were used. The proposed system showed significant correlation in both male and female stroke volume(r
Detection of Explosive RDX using Parallel Plate Waveguide THz-TDS
Yoo, Byung Hwa ; Chung, Dong Chul ; Kang, Seung Beom ; Kwak, Min Hwan ; Kang, Gwang-Yong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1939~1943
DOI : 10.5370/KIEE.2012.61.12.1939
In this paper we presented the detection of the explosive material RDX using a parallel plate waveguide (PPWG) THz time domain spectroscopy (TDS). Normally the explosive materials have been characterized through identification of vibrational fingerprint spectra. Until now, most of all THz spectroscopic measurements have been made using pellet samples where disorder effects contribute to line broadening such that individual resonances merge into relatively broad absorption features. In order to avoid such disadvantages we used the technique of PPWG THz-TDS to achieve sensitive characterization of explosive material RDX. The PPWG THz-TDS used in this work well established ultrafast optoelectronic techniques to generate and detect sub-picosecond THz pulses. The explosive material was analyzed as powder layers in
gap of metal PPWG. The thin later mass was estimated to be about
. Finally, we showed spectra of explosives from 0.2 to 2.4 THz measured using PPWG THz-TDS.
Optimal Design of Matrix-type SFCLs According to Turn Number of Reactors
Chung, Dong Chul ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1944~1947
DOI : 10.5370/KIEE.2012.61.12.1944
In this work, we investigated quench characteristics of matrix-type superconducting fault current limiters (MFCLs) according to the turn number of reactors. The reactors used in MFCLs apply magnetic field to superconducting elements within reactors when fault currents surge into MFCL systems. It makes the fast and simultaneous quenches between superconducting elements. Also reactors decrease the fault power burden of superconducting elements by bypassing the partial fault currents to itself, when quench occurs. These structure proposed in this work can be expected to achieve much more current limiting capacity even though it uses less superconductors compared with other type SFCLs. Three reactors were made by Bakelite. These reactors with the turn number of 190, 380 and 570, had the length of 270 mm and diameter of 80 mm. We reported experimental results, including fault currents, fault voltages and resistance in superconducting elements according to the turn number of reactors. We confirmed that experimental results will be useful in next future plan for the real power grid.
Modal Analysis and Testing for a Middle Spacer Grid of a Nuclear Fuel Rod
Ryu, Bong-Jo ; Koo, Kyung-Wan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1948~1952
DOI : 10.5370/KIEE.2012.61.12.1948
The paper presents modal testing and analysis in order to obtain the dynamic characteristics of a middle spacer grids of a nuclear fuel rod. A spacer grid is one of the important structural elements supporting nuclear fuel rods. Such a fuel rod can be oscillated by its thermal expansion, neutron irradiation and etc. due to cooling water flow under the operation of a nuclear power plant. When the fuel rod vibrates, fretting wear due to repeated friction motion between the fuel rods and spacer grids can be occurred, and so the fuel rod is damaged. In this paper, through modal analysis and testing, natural frequencies and modes of a middle spacer grid were calculated, and the following conclusions were obtained. Firstly the numerical first-seven natural frequencies for spacer grids of a fuel rod having complicated structures have a small difference within 3.8% with experimental natural frequencies, and so the suitability of simulation results was verified. Secondly, experimental mode shapes for a middle spacer grid of a nuclear fuel rod were verified by obtaining lower non-diagonal terms through MAC(Modal Assurance Criteria), and were confirmed by the simulation modes.
Development of Prevention Apparatus for Short-Circuit Faults Using the Line Voltage Drop of Neutral Wire
Kwak, Dong-Kurl ; Kim, Jin-Hwan ; Lee, Bong-Seob ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1953~1958
DOI : 10.5370/KIEE.2012.61.12.1953
The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The occurrence factor of the fire is electric arc or spark accompanied with such electric faults, specially short circuit faults. Earth Leakage Circuit Breaker (ELB) and Molded_case Circuit Breaker (MCCB), that is, Residual Current Protective Devices (RCDs) used on low voltage distribution lines cut off earth leakage and overload, but the RCD can not cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied in low voltage distribution panel are prescribed to rated breaking time about 30ms(KS C 4613), the RCDs can`t perceive to the periodic electric arc or spark of more short wavelength level. To improve such problem, this paper proposes a prevention apparatus using the line voltage drop of neutral wire and some semiconductor switching devices. Some experimental tests of the proposed apparatus confirm the validity of the analytical results.
Modeling of Converter-based Single-phase Load for Analysis of AC Substation System of Electric Railway
Son, Ho-Ik ; Yoo, Hyeong-Jun ; Kim, Hak-Man ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1959~1963
DOI : 10.5370/KIEE.2012.61.12.1959
Since electric railway load is variable largely due to starting and braking characteristics as well as various operation patterns, load modeling is not easy but complicated. For this reason, a simple technique for modeling of electric railway load of is required to analyze the AC substation system of electric railway. In this paper, a modeling technique of converter-based electric railway load is proposed and is tested using nonlinear loads on Matlab/Simulink.
An Evaluation of Selective Grounding Fault Protective Relaying Technique Performance on the Ungrounded DC Traction Power Supply System
Jung, Hosung ; Kim, Joouk ; Shin, Seongkuen ; Kim, Hyungchul ; An, Taepung ; Yun, Junseok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 61, issue 12, 2012, Pages 1964~1969
DOI : 10.5370/KIEE.2012.61.12.1964
This paper presents to verify the selective grounding fault protective relaying technique for the ungrounded DC traction power supply system. This system selectively blocks fault section when grounding fault occurred. In order to perform this verification, field test facilities have been installed on Oesam substation and Worldcup-Stadium substation, and field test process has been suggested. Also, selective grounding fault protective relaying components and rail voltage reduction device have been tested with the various trial examinations. In order to compare and evaluate performance of the selective grounding fault protective relaying function, field test system was modeled and the system fault simulation results were compared and evaluated with the field test result. Performance of selective grounding fault protective relaying function was evaluated with the above-mentioned process, and the fact that the system recognizes fault section irrespective of insulation between rail and ground and fault resistance from grounding fault.