• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.64-66
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• 2002

Recently. switched reluctance motor is noticed because it is simple in structure and mechanically strong. SRM has great competitive power, and the study is developed about improving the characteristics of SRM. The current density of winding becomes larger in designing SRM that has the characteristics of the low voltage and high current. Hence the current density of SRM of a vehicle is high. And in order that we drive SRM in variable speed and protect the switching device. the current of SRM is limited by chopping. So it is impossible to obtain object value of output characteristics by limited current. In this paper, the author design the shape of SRM from Miller's output equation, and verify the design of SRM by using FEM. The waveform of chopping current is predicted by simulation and concur with experimental result. And the torque is improved by applying overlap current.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.9
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• pp.787-796
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• 2013

In this paper, the visible light communication (VLC) techniques based on the carrier modulation are considered in order to realize the VLC application service that has the functions of the high speed optical sensing and the wide range reception from VLC transmitter. The VLC hardware circuits based on the 32.768 kHz low frequency carrier and 4 MHz high frequency carrier are designed and implemented respectively, and the signal waveform generated from the implemented circuits are observed. In addition, various performance experiments are done with the prototypes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.57-68
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• 2014

This paper propose a development of squirrel-cage induction motor(IM) for 5-phase 1.5kW, 220V, 60Hz in order to study a polyphase ac machinery that keep hold of advantages more than traditional three-phase a IM, such as reducing a amplitude of torque pulsation, decreasing electric noises, and increasing the reliability. Designed methods of the motor use a development tools with Maxwell 2D and Simplorer program. There are designed drawing of manufactured frames of the IM. amplitude and waveform of the generated electromotive force, FFT analysis of harmonics within output voltages and current, and reviewing a experiment results are shown by variable output. We are presenting a design and manufacture methods for the 5-phase squirrel-cage IM.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.2
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• pp.79-84
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• 2015

Voltage sags are considered the dominant disturbances affecting power quality. Dynamic voltage restorers(DVRs) are mainly used to protect sensitive loads from the electrical network voltage disturbances such as sags or swells and could be used to reduce harmonic distortion of ac voltages. The typical DVR topology essentially contains a PWM inverter with LC Filter, an injection transformer connected between the ac voltage line and the sensitive load, and a DC energy storage device. For injecting series voltage, the PWM inverter is used and the passive filter consist of inductor(L) and capacitor(C) for harmonics elimination of the inverter. However there are voltage pulsation responses by the characteristic of the LC passive filter that eliminate the harmonics of the PWM output waveform of the inverter. Therefore, this paper presented design and feedback performance of LC filter used in the DVRs. The voltage control by LC filter should be connected in the line side since this feedback method allows a relatively faster dynamic response, enabling the elimination of voltage notches or spikes in the beginning and in the end of sags and strong load voltage THD reduction. Illustrative examples are also included.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.34-40
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• 1999

In order to establish the design technique of the robust current controller in d.c series wound motor driver system, this paper proposes a method of the compensated Bang-Bang current control using d.c series wound motor driver system under the improperly variable load to get minimum time for the torque control. The compensated Bang-Bang current controller structure is simpler than that of PID plus Bang-Bang controller. This paper shows that a general 16 bits microprocessor is efficiently used to implement such an algorithm. The calculation time of software is extremely small when compared with that of conventional PID plus Bang-Bang controller. Both nonlinear operating characteristics of digital switching elements and describing function methods are used for the analysis and synthesis. Real-time implementation of the compensated Bang-Bang current controller is achieved. The concept of design strategy of the control and the PWM waveform generation algorithms are presented in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.3795-3801
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• 2011

The mathematical simulation of voltage and current waveform of the discharge lamp is useful for the analysis and design of ballasting circuits. This paper proposes a mathematical model which has lamp power and negative voltage drop in discharge lamp. Simulation applying the proposed model has been done, and the results are compared with the experimental results. Furthermore, in the paper, the ballast components(core, transformer) was designed such that high intensity discharge could be optimized for the automotive, by applying a method simulation based design.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.498-506
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• 2019

In this paper, we propose a PRF design method to improve the performance of the ESA radar, by excluding the interference from an improper PRF. Like the conventional method, the proposed method also considers the interference between the transmitted signal and the nadir signal, but additionally analyzes the relationship between the interference and the signal beamwidth. The simulation results show that the proposed method quantitatively and qualitatively excluded interference from the PRF and additionally dealt with the beamwidth broadening effect of an ESA radar.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1074-1086
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• 2019

This paper presents the design and implementation of an improved cascaded multilevel inverter topology with asymmetric DC sources. This experimental inverter topology is a stand-alone system with simulations and experiments performed using resistance loads. The topology uses four asymmetric binary DC sources that are independent from each other and one H-bridge. The topology was simulated using PSIM software before an actual prototype circuit was tested. The proposed topology was shown to be very efficient. It was able to generate a smooth output waveform up to 31 levels with only eight switches. The obtained simulation and experimental results are almost identical. In a 1,200W ($48.3{\Omega}$) resistive load application, the THDv and efficiency of the topology were found to be 1.7% and 97%, respectively. In inductive load applications, the THDv values were 1.1% and 1.3% for an inductive load ($R=54{\Omega}$ dan L=146mH) and a 36W fluorescent lamp load with a capacitor connected at the dc bus.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.3
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• pp.229-234
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• 2021

In this paper, a study was conducted on the power amplifier control required to design an eLoran transmitter system using a low-height antenna. The eLoran transmitter developed during the eLoran technology development project conducted in Korea used a small 35 m antenna due to the difficulty of securing a site for antenna installation. This antenna height is very low compared to the height of 750 m which is required for eLoran 100 kHz signal transmission without any radiation loss. In the case of using such a small antenna, not only the radiation efficiency of the transmission is lowered, but also the power module control must be performed more precisely in order to transmit the eLoran standard signal. The equivalent RLC circuit of the transmitter system was implemented and transient analysis was conducted to derive the input required voltage for satisfying the output requirement. The voltage waveform was also generated by the RLC circuit analysis to generate the eLoran signal. Furthermore, we suggest power width modulation method to control eLoran power amplifier module more sophisticatedly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.255-260
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• 2023

In order to spread LED lighting, LED lighting technology directly driven by alternating current (AC) commercial power has recently been introduced. Since current does not flow at a voltage lower than the threshold voltage of the LED, a non-conductive section occurs in the current waveform, and the higher the threshold voltage of the LED, the more discontinuous current waveforms are generated. In this paper, multi-LED modules are connected in series so that the threshold voltage can be adjusted according to the number of LED modules. A small number of LED modules are driven at a low instantaneous rectified voltage, and a large number of LED modules are driven at a high instantaneous rectified voltage to lengthen the overall lighting time of AC-LED lighting, thereby minimizing the luminance deviation of AC-LED lighting. In addition, the load current flowing through the LED module is adjusted to be the same as the design current even at the maximum rectified voltage higher than the design voltage, so that the light brightness of the LED module is kept constant. Therefore, even if the rectified voltage applied to the LED module changes, the AC-LED lighting in which the light brightness is constant and the luminance deviation is minimal has been realized.