• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.341-345
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• 1998

This paper presents performance and loss analysis of Auxiliary Resonant Commutation Snubber-linked (ARCS) three phase voltage source soft switching inverter which is operated under a condition of Zero Voltage Switching (ZVS). The system performances of this ARCS soft switching inverter which is controlled on optimal type I digital servo scheme are illustrated and evaluated on the basis of experimental results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.6
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• pp.43-51
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• 1983

A small-scale packet switching system is designed in compliance with the CCITT Recommen-dation X.25 Each switching node is controlled by a single microcomputer for all functions including terminal access control, packet-level control and link control. Basic protocol functions are successfdly implemented for the three basic hierarchical Igvels, and their results are discussed in detail.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.39-45
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• 2012

In this paper the digital control scheme of interleaved PFC for 3-phase modular UPS is presented. The interleaved PFC is composed of two identical PFC connected in parallel and each PFC is controlled by the interleaved switching signals which have the same switching frequency and the $180^{\circ}$ phase difference. As a consequence of the interleaving operation, the Interleaved PFC exhibits both lower current ripple at the input side and lower voltage ripple at the outside. Therefore, the switching and conduction losses as well as EMI levels can be significantly decreased. Simulation and experimental results verify the usefulness of the interleaved PFC.

• Journal of the Korean Ceramic Society
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• v.35 no.1
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• pp.11-16
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• 1998

$VO_2$ thin films have been prepared on borosilicate glass substrate using alkoxide method to characterize the effects of fabricating factors on thermochromic performance. The gel films formed by spin coating were converted to $V_2O_5$ phase during oxidizing heat-tratment and the $VO_2$ phase were formed by reducing heat-treatement. The thermochromic switching properties of $VO_2$ thin films are strongly affected by the crystal phase and microstructure and those could be controlled by reducing heat-treatment conditions. The ther-mochromic switching characteristics of $VO_2$ thin films synthesized were measured at IR (2.5$\mu\textrm{m}$) as the transition temperature of $63^{\circ}C$ the transition width of $3.6^{\circ}C$and the maximum and minimum transmittance of 84% and 14% respectively.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.103-106
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• 2001

In this paper, a soft switching half-bridge converter using secondary switches for output control and conduction loss reduction is proposed. The conventional half-bridge converter must be fixed on duty cycle for soft switching. The proposed converter was consisted of two added switches in series of the secondary rectifier diodes. The main switches with constant duty cycle are operated ZVS. The secondary switches are operated ZV-ZCS. Especially, the primary switches were fixed duty cycle for maximum voltage conversion ratio. Output of converter is controlled by duty cycle or phase-shifted time of secondary switches. The conduction loss of the proposed converter can be reduced by the secondary switches. The operation characteristic, analysis, simulation and experimental results of the proposed converter are presented.

• Journal of Information Display
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• v.5 no.2
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• pp.39-42
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• 2004

A novel fast-switching LCD with dual-domain bend (DDB) mode is described. DDB alignment is achieved using antiparallel-rubbed cell filled with chiral-doped LC. Initial alignment is mono-domain 180-degree twist. Tilt direction is controlled by oblique electric field to be counter direction in each domain. Twist-to-DDB deformation occurs continuously so that DDB mode does not require high-voltage initialization which is inevitable in Optically Compen sated Bend (OCB) mode. DDB gives wide and symmetric viewing angle in contrast to mono-domain bend formed from 180-degree twist showing strong asymmetry.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2005-2007
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• 2001

A controller design problem for a discrete-time Takagi-Sugeno (TS) fuzzy systems is discussed. The switching-type controller is employed in this study. A switching-type fuzzy-model-based controller is constructed based on the spirit of "devide and conquer". The design condition of this controller is formulated in terms of linear matrix inequalities (LMIs), which guarantees the global stability of the controlled TS fuzzy systems. An example is included for ensuring the effecienct of the proposed control method.

• Journal of Power Electronics
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• v.13 no.6
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• pp.1016-1023
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• 2013

Predictive current control offers the potential for achieving more precise current control with a minimum of distortion and harmonic noise. However, the predictive method is difficult to implement and has a greater computational burden. This paper introduces a theoretical analysis and experimental verification for an improved predictive current control technique applied to single phase grid connected voltage source inverters (VSI). The proposed technique has simple calculations. An ATmega1280 microcontroller board is used to implement the proposed technique for a simpler and cheaper control system. To enhance the current performance and to obtain a minimum of current THD, an improved tri-level PWM switching strategy is proposed. The proposed switching strategy uses six operation modes instead of four as in the traditional strategy. Simulation results are presented to demonstrate the system performance with the improved switching strategy and its effect on current performance. The presented experimental results verify that the proposed technique can be implemented using fixed point 8-bit microcontroller to obtain excellent results.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.2
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• pp.243-250
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• 2005

A new technique for improving the efficiency of single-Phase high-frequency switch-mode boost rectifiers is proposed. This rectifier includes an additional boost converter that parallels the main high-frequency switching device. The additional converter. which is controlled at lower frequencies. bypasses most of the current in the main switch and the high frequency switching loss is greatly reduced accordingly. The rectifier works cooperatively in high efficiency and as if it were a conventional rectifier with one switching device. The proposed scheme is verified by computer simulation using software PSIM.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.294-302
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• 2019

A capacitor common connected LLC resonant converter with auxiliary switches for a wide output voltage control range is presented in this paper. The proposed converter can be controlled in two ways to achieve a wide output voltage control range of Vo-3Vo. The first control method is performed through pulse width modulation of the auxiliary switches and primary switching devices. The second control method is conducted through frequency modulation of the primary switching devices configured to operate in full-bridge switching modes, when the auxiliary switches are turned off. The feasibility of the proposed converter is verified by the experimental results of a 5 kW prototype.