• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.721-725
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• 2012

In this paper, a novel analysis on the nonlinear response of a power amplifier (PA) with the intermodulation distortion (IMD) asymmetry is proposed based on the mutislice behavioral model. The coefficients of the odd-order and even-order polynomial of that model are represented with the PA practical circuit parameters such as intercept points, gain and amplitudes of excitation inputs. We also develop the analytic expressions to distinguish baseband frequency effect from second harmonic effect on the IMD asymmetry. We also validate the derived analytic expressions through measurements.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1195-1202
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• 2010

When modelling lots of induction motors to design and configure an engine room simulator, the 2 parameters equivalent circuit has many practical benefits as it reduces working hours considerably without requiring complicated technical data from makers except the ratings of motors. The basic properties such as torque and load current are shown well matched with real cases by this method, but almost the only drawback of 2 parameters circuit is that it reveals inherently higher power factor in the whole operation range due to disregarding the exciting current of the induction motor to maximize the simplification. This paper suggests a modelling module as a practical tool to compensate the power factor by inserting a virtual compensation current into the load current from 2 parameters equivalent circuit, and the simulated results show satisfactory outputs and the improved power factor indication by performance curves when compared to the cases of 2 parameters-equivalent circuit.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1242-1244
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• 1999

AVR parameter tuning for voltage control of power system generators has generally been done with the open-circuit model of the synchronous generator. When the generator is connected on-line and operating at rated load conditions, the AVR operates in an entirely different environment from the open-circuit conditions. This paper describes a new method for AVR parameter tuning using optimization technique with on-line linearized system model. As this method considers not only the on-line models but also the off-line open-circuit models, AVR parameters tuned by this method can give the sufficiently stable performance at the open-circuit commissioning phase and give the desired performance at the operating conditions. Also this method estimates the optimum parameters for desired performance indices that are chosen for satisfying requirements in some practical applications, the performance of the AVR can satisfy the various requirements.

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.4
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• pp.7-16
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• 1971

A negative resistance element in the form of current control can be obtained by using a pair transistor circuit. This negative resistance element can be used in the generation of square pulse, and also in the realization of pulse width modulation circuit by superposing signal current on its bias current. The each bias current of pair circuit increases alternatively according to the polarity of the input signal. In order to satisfy this condition, a modified full wave rectification circuit has been adopted for supplying the input signal. Theoritical analysis of pulse times and design guidances for practical modulation circuit parameters are presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.389-393
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• 2003

This paper presents circuit modeling and characterization of silicon-based on-chip integrated inductors in Giga Hertz range for wireless communication products. We compare several different designs of on-chip inductors for self-resonant frequency and quality factor. The measurement data could be used as a design guide for manufacturing practical spiral inductors for wireless applications. We provide the equivalent inductor circuit parameters from the actual measurement data.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.887-893
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• 2010

Modelling methods of 3 phase induction motors dependant on a lot of parameters give much drawbacks and difficulties when making engine room simulators due to computation burden and the time required for acquiring detailed technical data corresponding to actual induction motors. This paper suggests a practical method by a equivalent circuit with minimized parameters and some formulas to configure induction motors which requires only data on the name plates of motors, while it revealed satisfactory modelling performances on the resultant curves which are plotted for the torque, load current and power consume according to slip variation.

• Journal of Power Electronics
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• v.2 no.4
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• pp.288-296
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• 2002

In this paper, a high frequency transformer - assisted auxiliary active resonant commutated snubber (HFTA-ARCS) for voltage source soft switching pulse width modulated power conversion circuits is presented. A three phase voltage source type soft switching inverter incorporating HFTA-ARCS circuits in its three bridge legs can reduce current rating of auxiliary active power switches and has sensorless simplified control scheme which any specified boost current management is not required for soft switching. Its operation principle and digital control scheme are described and a practical design method of circuit parameters on this HFTA-ARCS circuit is also introduced on the basis of computer simulation. Moreover, this space voltage vector modulated soft switching inverter system with DSP-based digital control scheme Is discussed and its effectiveness is proved on the basis of performance evaluations. The operating performances of this inverter system are also compared with those of conventional three-phase hard switching inverter under practical conditions of specified parameters.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.733-740
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• 2013

The high-velocity electromagnetic forming (EMF) process is based on the Lorentz force and the energy of the magnetic field. The advantages of EMF include improved formability, wrinkle reduction, and non-contact forming. In this study, numerical simulations were conducted to determine the practical parameters for the EMF process. A 2-D axis-symmetric electromagnetic model was used, based on a spiral-type forming coil. In the numerical simulation, an RLC circuit was coupled to the spiral coil to measure various design parameters, such as the system input current and the electromagnetic force. The simulation results show that even though the input peak current levels were at the same level in each case, the forming condition varied due to differences in the frequency of the input current. Thus, the electromagnetic forming force was affected by the input current frequency, which in turn, determined the magnitude of the current density and the magnetic flux density.

• Smart Structures and Systems
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• v.14 no.2
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• pp.247-266
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• 2014

Conventional cantilevered piezoelectric energy harvesters (PEHs) are usually fabricated with continuous electrode configuration (CEC), which suffers from the electrical cancellation at higher vibration modes. Though previous research pointed out that the segmented electrode configuration (SEC) can address this issue, a comprehensive evaluation of the PEH with SEC has yet been reported. With the consideration of delivering power to a common load, the AC outputs from all segmented electrode pairs should be rectified to DC outputs separately. In such case, theoretical formulation for power estimation becomes challenging. This paper proposes a method based on equivalent circuit model (ECM) and circuit simulation to evaluate the performance of the PEH with SEC. First, the parameters of the multi-mode ECM are identified from theoretical analysis. The ECM is then established in SPICE software and validated by the theoretical model and finite element method (FEM) with resistive loads. Subsequently, the optimal performances with SEC and CEC are compared considering the practical DC interface circuit. A comprehensive evaluation of the advantageous performance with SEC is provided for the first time. The results demonstrate the feasibility of using SEC as a simple and effective means to improve the performance of a cantilevered PEH at a higher mode.