• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.928-935
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• 2018

In this paper, a compact fully printable bandpass filter is suggested for a low-frequency channel 3.2 GHz ~ 3.7 GHz in the Ultra-Wideband (UWB) communication system. It is featured with a small geometry of $0.5{\lambda}_g/15$ and a low insertion loss despite using FR4 as a cheap substrate of a high dielectric loss. This is made possible by generating zeroth-order-resonance (ZOR) from one cell comprising two series resonances obviously separated from one shunt resonance as a third-order bandpass filter. Especially, the series resonance elements are combined with spur-lines bent by 90 degrees, which makes the port-impedance matched well and eliminates spurious hikes in the stopband, while the overall size remains almost unchanged. The design is carried out by setting up the equivalent circuit and the circuit simulation is checked by the full-wave EM analysis. The structure is manufactured and measured to show that the circuit modeling and EM simulation results agree with the measured data.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.787-789
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• 2000

This paper describes the theory and practical design of Rogowski coil and active integrator. The coils and integrators have the ratings as follows. 1) current ratings between 20kArms and 200kArms 2) current duration 3 seconds 3) time constant of primary circuit looms 4) inner diameter of coil is suitable for mounting at the busbar $200mm{\times}200mm$. The actual results in the short-circuit tests and compare with other sensors, such that shunt. are given also.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.106-112
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• 2016

The high-voltage pulse generator consists of transformers of fundamental wave and harmonic waves, and shunt capacitors. The pulse has the fundamental wave and the harmonic waves that have been as a series circuit by the transformers to make high voltage pulse. This paper shows that pulse generator circuit is analyzed by using transformer equivalent circuits with the effect of load and simulated in time domain using Matlab program. The output voltage of pulse were obtained to 2.5kHz, 2.0kV. In high voltage circuit, capacitors are related to frequency band pass characteristics. Also, it is shown that the voltage of output pulse increases according to the growth of load.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.3
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• pp.115-123
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• 1985

A two phase chopper system with two separate groups of DC motors for regenerative braking is dealt with in this article. The main circuit consists of two sets of chopping parts, four diodes and two separate groups of DC motors. Although the proposed chopper circuit requires more circuit elements than the conventional two phase chopper system with combined output, it has the following advantages`(1). Ripple frequency of smoothing reactor current becomes twice as high as that of the conventional system, so the continuous current range and the ripple ratio are improved greatly. Therefore, the efficiency becomes even higher, the capacity of commutation equipment is reduced and the inductive interference become less.(2). Load current division becomes equalized. Therefore it is possible to drive not only series motors but also shunt, separately excited and compound motors.

• Transactions on Electrical and Electronic Materials
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• v.15 no.2
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• pp.103-111
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• 2014

This paper investigates the output powers of PV modules by predicting three unknown parameters: reverse saturation current, and series and shunt resistances. A theoretical model using the non-uniform physical parameters of solar cells, including the temperature coefficients, voltage, current, series and shunt resistances, is proposed to obtain the I-V characteristics of PV modules. The solar irradiation effect is included in the model to improve the accuracy of the output power. Analytical and Newton methods are implemented in MATLAB to calculate a module output. Experimental data of the non-uniform solar cells for both serial and parallel connections are used to extend the implementation of the model based on the I-V equation of the equivalent circuit of the cells and to extend the application of the model to m by n modules configuration. Moreover, the theoretical model incorporates, for the first time, the variations of series and shunt resistances, reverse saturation current and irradiation for easy implementation in real power generation. Finally, this model can be useful in predicting the degradation of a PV system because of evaluating the variations of series and shunt resistances, which are critical in the reliability analysis of PV power generation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.3-4
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• 2008

Photovoltaic module consists of serially connected solar cell which has low voltage characteristics. But, the other way, the whole current flow of PV module is restricted by lowest current of one solar cell. For the experiment, we make PV module composing the solar cells that have short circuit current difference of 0%, 1%, 3% and 5%. Using Light I-V and Dark I-V measurements, electrical characteristic parameters like Isc(short-circuit current), Voc(open-circuit voltage), Rs(series resistance), Rsh(shunt resistance) are analyzed. PV module of low current characteristics has electrical stress from other modules. And, such a module has a tendency of hot-spot suffering which leads degradation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.2
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• pp.236-242
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• 1986

The dependence of the current-voltage characteristics of hydrogenated amorphous silicon pin solar cells on the illumimination light intensity has been investigated. The open circuit voltage increases linearly with increasing the logarithm of light intensity up to AM 1, and nearly saturates above AM 1, indicating the open circuit voltage approaching the built-in potential of the pin solar cell above AM 1. The short circuit current density increase with light intensity in proportion to I**0.85 before and I**0.97 after light exposure. Since the series resistance devreses and shunt resistance increases with light intensily, the fill factor increases with light illumination. To increase the fill factor at high illumination in large area solar cells, t6he grid pattern on the ITO substrates should be made. Long light exposure on the solar cells gives rise to the increase of bulk resistance and defect states, resulting in the decrease of the fil factor and short circuit current density. The potential drop in the bulk of the a-Si:H pin solar cells at short circuit condition increases with decreasing temperature, and increases after long light exposure.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.558-560
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• 2004

Studies on the controlled switching method have been done to prevent the power system surges which cause the insulation deterioration and electro magnetic compatibility (EMC) problems during closing and opening of a circuit breaker. The controlled switching method controls the closing and tripping time in coincidence with the voltage or current to suppress switching surge. It is used to switch condenser bank, no load transformer, and shunt reactor. In this study, basic concept of the controlled switching is introduced, and also the test is performed to find parameters of the controlled switching in a 24kV vacuum circuit. And then, the control device hardware using TMS320C31 DSP has been designed and manufactured. It has been found that the application of IT technology to a circuit breaker is very effective to depress the switching surge.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.3
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• pp.171-178
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• 1987

A study of two phase chopper system with four separate groups of DC motors in powering. A novel two phase chopper system with four separate groups of DC motors which applies the principles of two phase chopper with two separate groups of DC motors is dealt with this article. The main circuit consists of eight sets of chopping parts, four diodes and four separate groups of DC motors. Four groups of DC motors are driven through the series and parallel connections to each other in accordance with the operating conditions of the choppers. Although the proposed chopper circuit requires more circuit elements than the conventional two phase chopper system with combined output or two phase chopper system with two separate groups of DC motors, it has the following advantages` (1). It is possible to drive twice as much motors as conventional system does, using esisting receiving-and equipments and motors. (2). It is possible to control load voltage continuously from 0 to source voltage by changing time-ratio from 0 to 1. (3). Load current division becomes equalized. Therefore it is possible to drive not only series motors but also shunt and separately exited motors. (4). When smoothing reactor L is small, harmonic components of the proposed circuit is not so large. Therefore, the value of L can be determined from viewpoints of allowable value of ripple-ratio and current unbalance factor.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.353-364
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• 1998

This paper presents a systematic approach to the modeling of power electronic circuits with systemlongrightarrowlevel simulation l languages. It is shown that a circuit model reduces to one of four basic types according to input/output conditions. The e elementary models for single series components and shunt components are derived which are integrated to develop a m model of given converter circuit. The constraints imposed on the model development-matching input/output conditions a and avoiding algebraic loop-are discussed in relation to the realization example of a buck converter circuit model. It is s shown that the constraints can always be fullfilled by introducing fictitious interface blocks, which is generalized to the c concept of model transformation.