• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.10
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• pp.470-476
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• 2005

In this paper PU control scheme is presented. The proposed scheme has following features. The one is oft-starting method which is used for preventing to flow large current in motor phase winding when motor starts. The ther is the selection of the level of the over current. The first feature is implemented by increasing the PWM duty lowly, the second feature is implemented by limiting the magnitude of the phase current level by which the over heat f motor by copper losses and magnetic saturation decreases. By the analysis using FEM considering load condition, the peed of mode transition from PW to single pulse control is selected and confirmed by simulation that there is no ver current occurs during the mode transition. For the verification of proposed scheme, the simulation using MATLAB Simulink with considering non-linearity of inductance profile from FEM analysis is performed and the experiment with SRM drive system which has the DSP controller and single Phase SRM are peformed.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.868-870
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• 2001

Salient pole rotor type single phase SRM(switched reluctance motor) can be use axial direction magnetic flux and radial direction magnetic flux at the same time. Then, it has higher energy density per unit volume and can be lessened the shaft length of motor or exciting magnetic force. Additionally, it's durability is good because it is simple structure and driving device. Prototype of Salient pole rotor type single phase SRM was fabricated by using parameters of three phase SRM and 3D FEM analysis. Also, driving device was fabricated for prototype. Speed and torque characteristic was confirmed through the experiments, and flux linkage, which is important parameter of SRM for generating torque, was measured. The induction emf was calculated by using ideal inductance graph and current graph. Calculated emf and measured emf was compared for confirming loss of prototype in this paper.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.641-643
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• 2005

It is usual to operate the long transmission line with transposition of each phase in order to avoid voltage unbalance due to unbalanced capacitances at each phase of the line end. This paper described the Ferranti voltage rise of line end, charging current and secondary arc current according to the transposition of line or not. The positive and negative sequence current was derived by the phase current, and then the unbalanced rate was calculated. Then, we obtained the reclosing dead time of the single phase reclosing scheme for 500 kV single circuit horizontal arrangement transmission line system.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.169-173
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• 2005

In this paper, a comparative study of modified phase-angle, extinction-angle, and pulse width modulation control techniques for the purpose of power factor improvement of single-phase AC-AC voltage regulators have been illustrated as applied to a single-phase ac voltage converter by an example of the widely used single-phase induction motor as a dynamic load. Observations on power factor, displacement factor and total harmonic distortion factor are described and discussed on the basis of the simulated and measured results of this work.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.409-414
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• 2010

This paper describes the surface form measurement of a spherical smooth surface by using single shot off-axis Fizeau interferometry. The demodulated phase map is obtained and unwrapped to remove the $2\pi$ ambiguity. The unwrapped phase map is converted to height and the 3D surface height of the surface object is reconstructed. The results extracted from the single shot off-axis geometry are compared with the results extracted from four-frame phase shifting in-line interferometry, and the results are in excellent agreement.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.264-271
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• 2014

Virtual synchronous generator (VSG) in single-phase to interface distributed renewable energy resources is investigated in this paper. Mathematical models and numerical analysis are utilized to illustrate the features of the VSG. Enhanced control strategy is presented to ensure the performance of the VSG. Besides, a second order generalized integer (SOGI) is employed to calculate the instantaneous output power of the VSG in virtual ${\alpha}{\beta}$ frame. By the means of a phase-locked loop based scheme, the VSG can seamlessly transform between islanded and grid-tied modes, which can meet the requirements of micro-grid. At last, the validation and the proposed approach are verified by the simulated results using PSCAD/EMTDC.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.284-286
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• 1995

The most common for starting a single phase induction motor is to install a starting condenser and a centrifugal switch in series with the auxiliary winding. Though this method is simple, life of single phase induction motor is short because of malfunction of a starting condenser and a centrifugal switch and efficiency improvement has limitation. In this paper, the starting characteristics of SPIM is improved by voltage and phase control strategy of auxiliary winding in removing a starting condenser and a centrifugal switch. Finally, the excellent starting performance of SPIM is shown through simulation and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.317-320
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• 1999

In this study, the piezoelectric ceramics PZT powder was synthesized by Wet-Dry combination method. And the flexible 1-3-0 type composites were fabricated with piezoceramic PZT and Eccogel polymer matrix embedded 3rd phase. Dielectric constant of 1-3-0 type composites was lower than that of single phase PZT ceramics. Thickness mode coupling factor k/sub t/ which was comparable with single phase PZT ceramics and mechanical quality factor Qm were about 0.65 and 6, respectively. These composites are considered as a good candidates for broad-band type transducer applications. The acoustic impedance of 1-3-0 type composites was lower than that of single phase PZT ceramics. Therefore, these composites would be better used for hydrophone applications.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.2
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• pp.22-27
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• 2001

Salient pole rotor type single phase switched reluctance motor is of simple and rigid structure, short shaft and simple driving circuit. Especially, the output power per unit volume of salient pole rotor structure is comparatively high because the magnetic fluxes of axial and radial direction are simultaneously used. Therefore, this motor will be used at small space and difficult maintenance situations. In this paper, the selecting method of proper pole arc, stator, and rotor dimension of salient pole rotor type single phase SRM is proposed.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.356-359
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• 2001

In this paper, the new control algorithm is proposed that compensates instantaneously the active and reactive components of the input currents by the synchronous d,q axis conversion of a single-phase current in controlling the single-phase AC/DC parallel converters for a high speed train. The leakage inductance of a transformer was used as a boost inductance and the ripple of a transformer's primary current was reduced considerably by the parallel operation of the two converters with a proper switching phase-shift. The stable and fast control response characteristic is certificated by a simulation.