• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.4
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• pp.153-157
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• 2010

In this paper, a dual band LNA (Low Noise Amplifier) with a LC-tank matching circuit is designed for 912MHz and 2.45GHz RFID reader. The operating frequency is decided by the LC-tank resonance. The simulated results demonstrate that S21 parameter is 11.683dB and 5.748dB at 912MHz and 2.45GHz, respectively, and the S11 are -10.796dB and -21.261dB, the S22 are -7.131dB and -14.877dB at the same frequencies. The measured NF (Noise Figure) is 0.471 and 1.726 at 912MHz and 2.45GHz, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.892-897
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• 2007

This paper presents the output filter design and the output characteristic analysis by cut-off frequency set up of the LCR filter on NPC multi-level inverter with trap-filter. The single-phase NPC three-level inverter operates at low switching frequency. The proposed LC trap filter is comprised of a conventional LCR output filter, by using LC trap filter the need for high damping resistor and low LC cut-off frequency is eliminated. Also. low damping resistor is increased the output filter system. The multilevel inverter system used NPC type inverter in proper system for high power application and controller is used DSP(TMS320C31). The effectiveness of proposed system confirmed the validity through SPICE simulation and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.153-156
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• 2004

We have studied electro-optic characteristics of transflective liquid crystal display (LCD) using in-plane switching mode. Unlike previous transflective LCD using a dual gap structure and multi driving circuit, this transflective LCD has a single gap structure and a single driving circuit. In the voltage on state, the electric field is applied horizontally to the LC directors, and then homogeneously aligned LC directors at initial state is rotated to with the electric field. But the twist angle of the LC directors in reflective area is lower than transmissive area. As a result, it is possible to design the transflective LCD with a single gap and a single driving circuit. The transflective display associated with this LC cell exhibits a wide viewing angle in both reflective and transmissive areas.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1538-1543
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• 2009

The electric ballast for ceramic metal halide lamp needs a protection circuit to prevent from over voltage and over current in the case that the lamp or the electric ballast are in faults. In this paper, cost-effective and high performance protection circuit is proposed for the electric ballast. The proposed protection circuit is adapted to the electric ballast with $LC_SC_P$ resonance type half bridge inverter. The experimental results demonstrate that the proposed circuit can protect effectively under open and short fault conditions.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1502-1503
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• 2007

In this paper, inductive coupled LC balun has been desi gned and simulated for embedding into an organic packaging substrate. Inductive coupling method was applied to obtain wide band characteristics, and high dielectric film was utilized to reduce a size of the balun. The proposed balun has a novel scheme which consists of three embedded LC resonators with inductive coupling. This proposed balun has relatively small inductance and capacitance values which can be easily embedded into the organic packaging substrate. Furthermore, it has a good phase imbalance characteristic. The simulated results of proposed balun are an insertion loss of 1.2 dB, a return loss of 10 dB, a phase imbalance of 1 degree at frequency bandwidth of 750 MHz ranged from 1.8 GHz to 2.55 GHz, respectively. This balun has an area of $2mm{\tims}3.5mm{\times}0.66mm$ (height).

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.5-6
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• 2016

This paper introduces a high efficiency bidirectional resonant converter using an additional LC auxiliary circuit for dcdistribution applications. The LC auxiliary circuit operates as a variable inductor and the additional LC circuit helps to increase the effective magnetizing inductance, thereby reducing the turn-off and primary circulating current. A 5 kW bidirectional converter for dc-distribution system is implemented to verify the validity of the proposed method. The experimental results show the high efficiency characteristics of the proposed converter over the wide range of load in both direction of power flow. The maximum efficiency of the proposed system was 98.1 % at 3 kW.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.155-166
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• 2016

It is important to configure capacitance(C) of the capacitor and the induction coefficient(L) of the work coil on the resonant circuit design stage in order to induce heating on the object by a precise and constant frequency components in the electromagnetic induction heating equipment. Work coil conducts a direct induction heating according to heating point and area of the object which has a fixed heat factor so that work coil is designed to has fixed value. On the other hands, Capacitor should be designed to be changed in order to be the higher the utilization of the entire equipment. It is extracted the samples by variation of single electrode capacity from the selection stage of raw materials for capacity to the stage of process design for output of the high frequency LC resonance of 700kHz on 1000 VAC maximum voltage and current to $200I_{MAX}$. It is suggested fundamental experiment results in order to prove relation for the optimal design of HF-LC resonance conduction-cooled capacitor based on the response of frequency characteristics and results of output parameters according to variation of the capacitance size.

• Polymer(Korea)
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• v.28 no.4
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• pp.298-304
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• 2004

We fabricated a polymer dispersed liquid crystal (PDLC) cell using LC with negative dielectric anisotropy and UV curable monomer exhibiting transparent state initially (called normally transparent (NT)) and studied the electro-optic characteristics. The NT PDLC cell made with the ratio of LC : monomer = 70/30 wt%, curing temperature of 20 $^{\circ}C$ and strong UV intensity of 198 ㎽/$\textrm{cm}^2$ had high contrast ratio and showed good electro-optic characteristics. In this condition, LC is aligned vertically on the substrate due to the vertical alignment layer and the polymer made with the UV exposure does not influence the alignment of the LC much. Therefore, the transmittance at the zero voltage is very high and the scattering state of the cell is good after applying the voltage because LC with negative dielectric anisotropy tries to align perpendicular to the field. And also, the NT PDLC cell showed better viewing angle characteristics than that in the normally scattering (NS) PDLC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.840-845
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• 2013

In this paper, the broadband frequency double down-converter based on LC filter technologies has been designed and implemented, and its performances are introduced. The Designed frequency double down-converter is consisted with a low-noise amplifier, mixer, IF amplifier, LC filter, DC-block capacitor and RF-bypass capacitor. Especially, instead of active devices of a typical converter, the suggested converter designed using passive devices to provide both low-power consumption and low-cost model. As results of the measurement, the implemented frequency double down-converter realizes the broadband performance with the bandwidth of 100MHz (13~113MHz) at the center frequency of 63MHz, and its gain is approximately 40dB.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.27-34
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• 2004

In this paper, we designed the electronic ballast for the 400[W] hight pressure sodium lamp using the half-bridge inverter Inductance and capacitance in the proposed equivalent LC series resonant circuit are calculated theoretically. We performed the simulation of the LC series half-bridge inverter circuit using the IsSPICE and the electronic ballast for the high pressure sodium lamp were implemented for verifing the simulation results. In the experimental results, the specification of the implemented electronic ballast are almost same with the simulated one. The experimental results show the good performance as PF 99.3[%], $A_{THD}$ 10.01[%], lamp efficiency 119[lm/W] at the output 400[W].].