• Journal of Industrial Technology
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• v.27 no.A
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• pp.149-155
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• 2007

The counter emf(electromotive forces) of a permanent magnet multi-phase brushless motor is generally a non-sinusoidal wave or a non-ideal trapezoid. So, conventional modeling using a sinusoidal wave or an ideal trapezoid counter emf can result in errors. In order to reduce modeling errors for simulation and analysis the properties of a multi-phase brushless AC motor, this paper proposes a phase variable model that is a mixed modeling technique using both Finite Element Analysis(FEA) based circuits and motor voltage equations. The phase model parameters including the counter emf voltage waveform are obtained by using of FEA, and the mixed modeling technique based on circuits and equations is used to implement a simulation model for multi-phase brushless AC motors with any counter emf voltage waveforms. Adequacy of the proposed model is established from the simulation and experimental results for a seven-phase brushless motor.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.8
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• pp.122-130
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• 1995

To reduce the shock in shifting, the clutches and the brakes in automatic transmission have to be connected smoothly and disconnected rapidly. It is PCSV(Pressure Control Solenoid Valve) that paly this role of automatic transmission. In this paper, there were two steps in the analysis of the PCSV. The first step was modeling the elctromagnet by the permeance method. The second step was modeling the hydraulic circuit by the pressure differential equa- tion. In addition to this modeling, a experiment was performed and the commercial package program was used in order to justify modeling. The result of modeling coincide with the result of experiment and commercial package program. As a result, this modeling is usable in analysis of dynamic characteristics of the PCSV.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.6
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• pp.42-50
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• 2006

This paper addresses the optimized thermal modeling methodology for spacecraft board level thermal analysis. A direct thermal modeling of external and internal structure of active parts which have high power dissipation is newly proposed, based on conventional plate modeling for Printed Circuit Board(PCB). The parts thermal modeling results were compared with other generic methodologies and verified by thermal vacuum test. This parts thermal modeling was directly applied to thermal analysis of CS(Communication Subsystem) board of HAUSAT-2 small satellite. As a result, it was confirmed that the parts thermal modeling can complement other conventional modeling methodologies. A parts thermal modeling is very effective for thermal control design, since the existing thermal problems can be solved at the parts level in advance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.263-269
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• 2012

In order to present that the electromagnetic compatibility standards following the frequency goes up which is based automotive electronics, in this paper, a hybrid/electric vehicle battery which reflects the frequency of the equivalent circuit model is introduced. By using this circuit modeling, the impedance characteristics can be analysed and an analyze of battery one cell is finished. Using this model, each different from the discharging situation, the discharge characteristic curve could be led. Basic theoretical approaches and measuring results through MATLAB and experimental validation of the EIS measurement equipment was used.

• ETRI Journal
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• v.32 no.6
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• pp.969-971
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• 2010

Based on a de-embedding technique, a new method is proposed which is capable of evaluating chip impedance behavior over absorbed power in flip-chip bonded UHF radio frequency identification transponder ICs. For the de-embedding, four compact co-planar test fixtures, an equivalent circuit for the fixtures, and a parameter extraction procedure for the circuit are developed. The fixtures are designed such that the chip can absorb as much power as possible from a power source without radiating appreciable power. Experimental results show that the proposed modeling method is accurate and produces reliable chip impedance values related with absorbed power.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.121-127
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• 2004

Electric ballast is widely used to turn on the fluorescent. Electric ballast measure occurrence of harmonic through the actual measurement and it is simulated by modeling equivalent circuit for harmonic analysis. The purpose of this paper is to give an equivalent circuit modeling methodology for the harmonic currents generated by single-phase personal computer loads to evaluate a commercially available series resonant filter for the harmonic currents compensation based on the IEC std 61000-3-2 and IEEE 519 standards for limiting harmonic distortion.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.180-188
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• 2003

In the precision motion device, the frictional problem by mechanical friction causes serious effects on the system performance. Various researches have been executed to solve this problem, but classical fluid lubrication method has some disadvantages in precision motion under clean environment. Therefore, the magnetic bearing and contact-free systems have been focused on with its pollution-free characteristics. In this paper, we treat modeling and analysis of electromagnets not only for magnetic bearing but also fer contact-free electromagnetic actuators. Three types of electromagnet for various applications are modeled and analyzed by magnetic circuit theory and the validity is verified by experiments.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.4
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• pp.21-27
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• 2007

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. Therefore the prediction of impact energy in design process is very helpful to the most of breaker manufacturers. In this study, we carried on modeling and simulation of a hydraulic breaker to predict impact energy via commercial CAE software. The modeling and simulation of a hydraulic breaker was achieved with two parts. One is a hydraulic circuit analysis part via AMESim and the other is impact strain analysis part via ANSYS.

• ETRI Journal
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• v.34 no.4
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• pp.633-636
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• 2012

A dynamic analysis of an amorphous silicon (a-Si) thin film transistor liquid crystal display (TFT-LCD) pixel is presented using new a-Si TFT and liquid crystal (LC) capacitance models for a Simulation Program with Integrated Circuit Emphasis (SPICE) simulator. This dynamic analysis will be useful when predicting the performance of LCDs. The a-Si TFT model is developed to accurately estimate a-Si TFT characteristics of a bias-dependent gate to source and gate to drain capacitance. Moreover, the LC capacitance model is developed using a simplified diode circuit model. It is possible to accurately predict TFT-LCD characteristics such as flicker phenomena when implementing the proposed simulation model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.249-252
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• 1997

The resolution of analog sensor is determined by its sensitivity and amplitude of noise. This paper presents modeling of inductive gap sensor base on equivalent magnetic circuit and analysis of sensitivity. The model of inductive gap sensor is verified by the experimental results. Then we can simulate static characteristic of inductive gap sensor using this model. Computer simulation show that sensor's sensitivity and linearity are affected by magnetic flux's leakage and fringing, and that they are affected by shape of sensor probe.