• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.454-454
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• 2000

An active-C biquadratic filter structure is proposed which consists of only seven OTAs and two grounded capacitors. The proposed circuit can simultaneously realize lowpass, bandpass and highpass transfer functions without changing circuit topology. This technique provides many advantages which include low passive and active sensitivities and, moreover, its Q-factor is electronically tunable and separately from the tuning of the natural angular frequency ${\omega}_o$. PSPICE simulation results are obtained that confirm the theoretical analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.381-386
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• 2002

This paper presents a piezoelectric shunt methodology to reduce unwanted vibration of optical disk drive(O.D.D.). After briefly investigating a second-order mechanical vibration absorber model, the O.D.D. structure is incorporated with the piezoelectric shunt circuit. In order to evaluate feasibility of multi-mode passive damping of the structure, admittance measurement of piezoceramic is undertaken. The parameters are optimally tuned by admittance measurement results on the basis of the circuit model and displacement transmissibility is evaluated. To verify validity of admittance measurement result, experiment is performed and vibration reduction is achieved at two different modes.

• 한국수소및신에너지학회논문집
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• 제19권5호
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• pp.417-422
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• 2008

In this paper, a novel DC/DC low-voltage high-current converter circuit is proposed to improve the efficiency of power converter used in the grid-connected fuel-cell generator system. We proposed a novel high efficiency grid-connected power conditioning system for RPG fuel cell. On the result of that, the loss of system was decreased rapidly by driving stack within the condition of maximum efficiency. The peak currents of the current-type inductor and the transformer's coil are reduced by synchronizing switching frequency of Buck-type converter is increased twice as the Push-Pull converter's switching frequency. The novel structure of DC/DC converter is able to realize ZVS-ZCS in fuel-cell system is proposed. The proposed switching component of Push-Pull converter has the ZVS and ZCS function by using the circuit of new passive clamp.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.155-158
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• 2000

Circuit configurations for realizing of biquadratic current transfer functions using current conveyors (CCIIs) are presented. The circuits are composed of three multiple-output CCIIs and four passive elements (two resistors and two grounded capacitors), and when current controlled conveyors (CCIIs) in place of CCIIs are employed, the circuit can be realized using three multiple-output CCIIs and two grounded capacitors. Use of grounded capacitors is suitable for integrated implementation. The cutoff frequency of a realized filter with current gain K can be tuned independently of Q by the value of K.

• Carbon letters
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• 제13권1호
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• pp.17-22
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• 2012

Currently, graphene is a topic of very active research in fields from science to potential applications. For various radio-frequency (RF) circuit applications including low-noise amplifiers, the unique ambipolar nature of graphene field-effect transistors can be utilized for high-performance frequency multipliers, mixers and high-speed radiometers. Potential integration of graphene on Silicon substrates with complementary metal-oxide-semiconductor compatibility would also benefit future RF systems. The future success of the RF circuit applications depends on vertical and lateral scaling of graphene metal-oxide-semiconductor field-effect transistors to minimize parasitics and improve gate modulation efficiency in the channel. In this paper, we highlight recent progress in graphene materials, devices, and circuits for RF applications. For passive RF applications, we show its transparent electromagnetic shielding in Ku-band and transparent antenna, where its success depends on quality of materials. We also attempt to discuss future applications and challenges of graphene.

• 한국조명전기설비학회지:조명전기설비
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• 제13권2호
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• pp.149-149
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• 1999

This paper is to present a selected method of circuit parameters in the inverter part of the electronic dimming ballast for fluorescent lamps, that is adequate to use with the prevailing dimming controller IC. Through the experiment result using the prototype of the electronic dimming ballast produced by this method, its validity is verified from the electrical and light output characteristics on fluorescent lamps. Also, it is feasible to remote automatic and passive control fur dimming electronic ballast as using a microprocessor, and we easily recognize the lamp condition owing to make a program indicate abnormal behavior for fluorescent lamp at PC screen.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.125-130
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• 2002

This paper examines the application of high voltage static var compensator(SVC) with cascade multilevel inverter which employs H~bridge inverter(HBI). The SVC system is modeled using the d-q transform which calculates the instantaneous reactive power. This model is used to design a controller and analyze the SVC system. From the mathematical model of the system, the design procedures of the circuit parameters Land C are presented in this thesis. To meet the specific total harmonic distortion(THD) and ripple factor of the capacitor voltage, the circuit parameters Land C are designed. Simulated and experimental results are also presented and discussed to validate the proposed schemes.

• 전기학회논문지P
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• 제57권4호
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• pp.370-376
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• 2008

Power capacitors is widely used for power factor correction and component of passive filter in the user power systems. Recently, application of non-linear load is gradually increased. Non-linear load produces harmonic components of current. There are series resonance and parallel resonance when capacitors are applied in the user electrical application. If this harmonic component matches resonance, voltage and current is magnified and has severely an influences on capacitor. This paper purposes a new method for the magnitude of voltage and current by the frequency scan analysis without equivalent circuit for the actual circuit at the resonance condition.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.56-63
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• 2019

Typical negative group delay circuits (NGDC) are analyzed in terms of signal attenuation, group delay, and bandwidth using S-parameters. By inverting these formulations, we derive and present the design equations (for NGD circuit elements) for a desired specification of the two among the three parameters. The proposed design method is validated through simulation examples for narrow- and wide-band pulse inputs in the time and frequency domains. Moreover, an NGDC composed of lumped elements is fabricated at 1 GHz for measurement. As a function of frequency, the circuit-/EM-simulated and measured group delays are in good agreement. The provided simple NGDC design equations may be useful for many applications that require compensations of some signal delays.

• 전자공학회논문지B
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• 제33B권5호
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• pp.152-158
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• 1996

A novel resonant pulse control technique which generates high-quality sinusoidal output voltage from a resonant dc link inverter is presented for UPS applicatons. The proposed control technique limits resonant voltae overshoot without any passive or active clamp circuit, resulting in resonant pulses iwth uniform amplitude and high efficiency. The output voltage is controlled by the third order contorller iwth an inner loop of th efilter inductor current and the feedforward controller. Analysis and design of the proposed control technique are illustrated and verified on a 5kVA experimental unit.