• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1099-1105
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• 2006

In this paper, the equivalent circuit model of a Rosen-type multilayer piezoelectric transformer(MPT) has been proposed based on the Mason's equivalent circuit model and the principle of single layer piezoelectric plate. From the piezoelectric direct and converse effects, the symbolic expressions between the electric inputs and outputs of the MPT have been derived from the equivalent circuit model. A simplified equivalent circuit model of the MPT whose driving part has a single input form has been proposed. The symbolic expressions of the driving part have been derived from the simplified equivalent circuit model and the model was compared with the multi-input equivalent circuit model through the simulation. In the comparisons between the simulation results and the experimental data, output voltage is 630 Vp-p in case of 11-layered MPT and 670 Vp-p for 13-layered MPT over the experiment range. As the load resistance increases, output voltage increases and saturates over $300k{\Omega}$ and the resonant frequency changes from 102 kHz to 103 kHz. The simulation and the experimental results agree well over different load resistances and frequencies.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.11
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• pp.440-444
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• 1985

Voltage equations of a synchronous machine are derived from the electromagnetic field theory in order to develop a new equivalent circuit model considering core loss. The result from the new equivalent circuit model is superior to that of the conventional one in the analysis of machine performance and characteristics on optimal efficiency control of a synchronous motor.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.1
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• pp.34-38
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• 2005

The finite element method is very flexible for new shapes and provides flux distribution, magnetomotive force, eddy currents, and torques. However, it requires lengthy computational time in order to achieve desired accuracy. The magnetic equivalent circuit method takes less computation time than the finite element method. Therefore, the finite element method is mainly used to confirm the completed design. The magnetic equivalent circuit method is convenient for complicated analysis of the transient state of the induction motor. The magnetic equivalent circuit method is restricted to only one direction of magnetic flux. In this paper, the construction elements (that is, stator iron, rotor iron, yoke, air gap, etc.) of the squirrel cage induction motor were represented by a flux tube and the air gap magnetomotive force was calculated by the magnetic equivalent circuit method. Starting transient torque and phase current of the squirrel cage induction motor were verified by the theoretical calculation and the experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.109-112
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• 2013

It is well known that the maximum torque of a 3-phase induction motor does not vary as the resistance of rotor varies by proportional shifting. However, proportional shifting is derived using simplified equivalent circuit of induction motor. Therefore, there are some errors in the torque characteristics shown in the text book. This paper presents the torque characteristics using not simplified equivalent circuit but equivalent circuit. Errors produced by simplified equivalent circuit are presented.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.4
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• pp.159-164
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• 2003

In this paper, a three-dimensional finite element method and construction of equivalent-circuit for a linear ultrasonic motor are presented. The validity of three-dimensional finite element routine in this paper is experimentally confirmed by analyzing impedance of a piezoelectric transducer. Using this confirmed finite element routine, impedance and vibration mode of a linear ultrasonic motor are calculated. Elliptical motion of contact point between vibrator and rail of the linear ultrasonic motor is shown for determination of contact points. By using the finite element method and analytic equations, characteristics of the linear ultrasonic motor, such as thrust force, speed, losses, powers and efficiency, are calculated. The results are confirmed by experiment. Finally, equivalent circuit parameters of the linear ultrasonic motor are obtained using the three-dimensional finite element method and analytic equations.

• Journal of electromagnetic engineering and science
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• v.4 no.1
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• pp.30-36
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• 2004

We determined equivalent circuit parameters of a 1.5 cell S-band RF gun cavity from the resonant characteristics of its decoupled cavities(half cell and full cell) using the code SUPERFISH. Equivalent circuit parameters of the 1.5 cell RF gun cavity resonated in the 0-mode were obtained easily from the circuit parameters of each decoupled cavities. In order to obtain equivalent circuit parameters for the $\pi$ -mode cavity, we calculated the differences of the resonant frequencies and the equivalent resistances between the 0- and $\pi$ -modes with slight variations of the radius and thickness of the coupling iris. From those differences, we obtained R/Q value and equivalent resistance of the $\pi$ -mode, which are directly related to the equivalent circuit parameters of the coupled cavity. Using calculated R/Q value, we can express equivalent inductance, capacitance and resistances of the RF gun cavity resonated in the $\pi$ -mode, which can be useful for analyzing coupled cavities in a steady state.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.253-256
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• 1991

Tie constructed the equivalent circuit of the magnetotransistor by the representation of the operating principle as two independent current sources. The equivalent circuit has been analyzed quantatively and the calculated values agreed to the experimental ones. It has been found out that the structure of MT inflenuces on the relative sensitivity and the structure parameters can be extracted from the equivalent circuit.

• Journal of KSNVE
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• v.6 no.5
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• pp.645-652
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• 1996

In this paper an identification method is presented to obtain the equivalent electric circuit model of a wideband underwater acoustic piezoelectric vibrator. Unknown parameters involved in the equivalent circuit are indentified using the measured electrical admittances in air. The proposed method is applied to an example transducer. The validity of equivalent circuit model is demonstrated by the comparison between the experimental measurements and analytical calculations of TVR(transmitting voltage response) in water.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.595-600
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• 2023

In this paper, a modified equations of the T-equivalent circuit of the transmission line with the arbitrary electrical length is suggested. The suggested equations can be calculated without limitation of the equal branch-line. So, a modified T-equivalent circuit can be made with the arbitrary position of the open-stub. Also, the modified T-equivalent circuit can be applied in the arbitrary electrical length and impedance of the transmission line. For example, the λ/4 impedance transformer is converted with 4 divided T-equivalent circuit. The converted λ/4 impedance transformer has the size reduction ratio of 39.4%.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.153-156
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• 2001

This paper analyzes the 74LS381 ALU and designs its equivalent circuit. The 74LS381 ALU is arithmetic logic units(ALUs)/function generators that perform eight binary arithmetic/logic operations on two 4-bit words. However there are only little information to understand and design this circuit. Thus, we not only analyzed it but also designed an equivalent circuit to the 74LS381.