• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1235-1240
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• 2008

In this paper, we presented an active RFID system in 2.45GHz range including LNA, Mixer and gain block. And in this work, a link budget model for RFID applications are proposed. We describe the detailed design and implementation of our system. Our components in RFID system has features such as low Noise Figure, reliable energy budget, and standard compliance with ISO 18000-4. Our receiver is effective for development and evaluation of prototype applications because of the flexibility of the design hardware. So, our platform will be suitable for versatile item management applications.

• Journal of Power Electronics
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• v.8 no.4
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• pp.317-324
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• 2008

This paper proposes a Multiband Shunt Hybrid Active Filter (SHAF) with sensorless control. A plant is modeled in the discrete- time domain and a controller is designed using the Pole shifting law in the polynomial domain. This control approach is very useful for filtering the load harmonics with reduced sensor counts where a low cost solution like SHAF is required. Multiple Synchronous Reference Frames (MSRF) and low pass filters are used to measure the $5^{th}$ and $7^{th}$ harmonic components separately from the load and filter currents. Individual current controllers are designed for the $5^{th}$ and $7^{th}$ harmonic currents. Control is realized in the stationary, three-phase (abc) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models, as well as experimentally on a full-scale distribution system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.2
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• pp.76-82
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• 2006

This paper investigates the magnetic field behavior and its iron losses in the stator core using electrical steels. The analysis model is a brushless motor with the permanent magnet. The elliptical rotating and alternating flux distributions with non-sinusoidal waveform are obtained by Finite Element Method and then their harmonic components are extracted. Based on these results, the local iron losses in the stator core caused by the harmonic flux are calculated. And then this paper explains the relation between flux waveform and iron loss produced in each part of the stator core. Furthermore, the iron loss at no load condition is measured and compared with the analysis results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.81-85
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• 2006

The motion of a system composed of a plate, constant springs and varying dampers is considered when the system is subject to harmonic force. Letting the frequencies of harmonic force and damper variation ${\Large f}_1\;and\;{\Large f}_2$, respectively, the displacement at the center of the plate has the strongest component at frequency ${\Large f}_1$. The angular displacement of the plate has strong components at ${\Large f}_1-{\Large f}_2$, and the natural frequency of the rotational mode of the system. If these two frequencies coincide, the plate oscillates with almost single frequency and a large amplitude. These results can be applied to development of a moment shatter with low frequencies.

• Journal of Magnetics
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• v.18 no.2
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• pp.212-215
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• 2013

This paper deals with torque harmonic characteristics and its reduction design of induction motors for electric vehicle (EV) propulsion. For calculating the stator harmonic flux of squirrel-cage induction motor, the numerical methods have been employed on the structural configuration design of stator and rotor teeth. In particular, torque ripples including spatial harmonics are obtained by Finite Element Method (FEM), and their individual harmonic components are identified with Fast Fourier Transform (FFT). In this paper, design modification on the teeth surface gives rise to the significant reduction of torque ripples including spatial torque harmonics, which have been obtained with FEM.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2178-2180
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• 1998

Recently, for increasing consumed power and informational society, confidence of power supply is demanded. Beside, owing to most of these loads are nonlonear, utility line is polluted by these components, therefore, it is demanded compensation of harmonic current. In times past, special order of harmonic current is only compensated by passive filter, but active power filter can compensate whole harmonic current. Therefore, this paper propose uninterruptable power supply(UPS) with performance of active power filter.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.6
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• pp.465-472
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• 2016

A nonlinear load causes harmonic distortion and hampers the performance of other loads or distributed generation (DG) sources connected to the point of common coupling (PCC). This study proposes a new control strategy to reduce harmonic components, such as fifth and seventh harmonics, at the PCC under nonlinear loads in islanded microgrids, which comprise more than two DG sources. The proposed control scheme enables the DG source to share the power commanded by the control center as well as to compensate for the voltage harmonics at the PCC. The reference current is estimated from the voltage harmonics and injecting power; thus, the control scheme is implemented without any additional hardware devices. The simulation and experimental results are presented to verify the effectiveness of the proposed control method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1093-1102
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• 1994

PWM converters employing GTO's are proposed to be used for the currently planned Korean High-Speed Train system. In this paper, operating methods and harmonic spectrums are investigated for the PWM modulated voltage controlled GTO AC/DC converter used in the High-Speed Train System. It is shown that harmonic components can be controlled by varying carrier frequency in PWM modulation schemes. Then the input power-factor control scheme is suggested and analyzed. It is found that the power-factor can be varied by controlling the converter input voltage and phase angles between the input supply voltage and the converter input voltage. Finally, simulation programs are developed and converter systems are implemented.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.671-679
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• 2004

This paper presents the on-line current controller tuning method of grid-connected inverter using PSO(particle swarm optimization) technique for minimizing the harmonic current. Synchronous frame PI current regulator is commonly used in most distributed generation. However, due to the source voltage distortion, specially in weak AC power system, current may contain large harmonic components, which increase THD(total harmonic distortion) and deteriorates power quality. Therefore, some tuning method is necessary to improve response of current controller. This paper used the PSO technique to tune the current regulator and through simulation and experiments, usefulness of the tuning method has been verified. Especially in simulating the tuning process, ASM(average switching model) of inverter is used to shorten execution time.

• Journal of Power Electronics
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• v.16 no.1
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• pp.48-56
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• 2016

This paper proposes a method for detecting irreversible demagnetization using the harmonic analysis of back electromotive force (BEMF) in interior permanent magnet-type brushless DC motors. First, demagnetization patterns, such as equality, inequality, and weighted demagnetizations, are defined and classified by considering the possibility of demagnetization resulting from motor operating characteristics. Second, an available diagnostic model for the harmonic analysis of BEMFs is defined according to pole-slot coefficients because the characteristics of BEMFs under demagnetization conditions are affected by the combination of poles and slots. Third, BEMFs and their harmonic components under normal and demagnetization conditions are analyzed through simulation and experiment to verify the proposed demagnetization detection technique.