• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.365-366
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• 2010

본 논문에서는 양방향성 Z-소스 DC-DC 컨버터 2대를 이용한 단상 Z-소스 부스트 인버터를 설계하고 분석하였다. 두 대의 컨버터를 이용한 인버터 시스템은 종전의 PWM 인버터 시스템과 달리 두 컨버터에서 출력되는 두 교류 출력을 이용한 것으로 전체 시스템의 교류 출력전압에 포함된 고조파가 낮다. 또한, 컨버터 내부를 구성하는 L-C로 인해 추가적인 출력필터 설계가 불필요 하다는 장점이 있다. 본 연구에서는 종전의 부스트 컨버터 또는 벅-부스트 컨버터 방식이 아닌 두 대의 Z-소스 DC-DC 컨버터를 입력 DC전원과 출력 부하를 공통으로 하는 단상 인버터 시스템을 구성하고, 교류 출력파형 및 제어방법과 동작특성을 분석하였다.

• 대한의용생체공학회:의공학회지
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• 제6권1호
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• pp.5-12
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• 1985

In this paper Kalman filtering technique is applied to ultrasound signal to improve resolution capability, Ivhlch is in use of diagnostic imaging systems. The main advantage of Kalman filter algorithm for the analysis of reflected ultrasound signal is its recursive structure which can be easily adapted to tlme varing system. Because soft-tissues, such as liver, act as distributed acoustic low-pass filters which continually change the propagating pulse. tIne can put to practical use above advantage to find a suitable signal generallng model. In state-space description of the system, the 6th order system produces tl)e 1)esc spectral approximation to the source pulse As a result of spectrum analysis, 6th order estimator for two closely spaced ((p.5 mm) reflectors enhances resolution by 4dB-lOdB. By using this result, the possibility to detect even minute tumor is demonstrated.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1341-1346
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• 2004

Basic design for single-phase active power filter, which aims at railway applications provided with PWM-controlled converters, is comprehensively studided and its performance is presented in this paper, Active power filters are used to compensate railway signaling and public telecommunication interference due to the high-order harmonic currents generated in railway traction locomotives. A type of hybrid digital filter which is composed of low pass filter and high pass filter is proposed so that the desired harmonic reference current with accurate magnitude and phase shift can be extracted from catenary line current. A design criteria to determine input inductor L and output capacitor C is also described, considering voltage, current. PWM pattern, and switching frequency of the main converters, Finally, computer simulation and DSP-based experiments resulted from laboratory test are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.490-493
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• 2005

In order to reduce the harmonics in invertor output of the DVR system, typically LC filter is employed. In designing the LC filter, it is required to consider the gild impedance and the characteristic of the harmonics. In this paper, problems in the conventional way of designing the LC filter is analyzed and new LC fitter design technique is proposed. In the proposed technique, parameters of the LC filter are calculated considering grid impedance, THD, DC link voltage and phase lag. The validity and feasibility of the proposed method is verified through the simulations experiments. The DVR system with the proposed LC filter is being built and tested.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.28-29
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• 2013

DC-DC Buck Converter는 입력 전압보다 출력전압이 낮은 컨버터이며 강압형 컨버터라고도 한다. 입력과 출력이 같은 접지를 공유하는 회로에 쓰이며, 스위칭 소자를 이용하여 듀티비에 따라 출력전압을 제어할 수 있고, 출력단의 LC 필터를 통해 평활(평균)하여 직류전압을 얻을 수 있다. DC-DC Buck Converter는 제어가 간단하고 설계가 쉬워 주로 회로의 파워부에 많이 쓰이고 있으며, 본 논문에서는 DC-DC Buck Converter의 기본형과 2Stage DC-DC Buck Converter 그리고 기본형의 GND단에 L을 추가한 DC-DC Buck Converter의 응답특성을 비교 및 분석을 함으로써 이론적 해석과 시뮬레이션을 통한 특성을 비교 하고자 한다.

• 전기학회논문지P
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• 제50권3호
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• pp.101-108
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• 2001

Frequency is an important operating parameter of a power system. Electric power systems sustain transient frequency swings whenever the balance between generation and load does not no longer hold. To cope with this constraints, it requires an accurate and high speedy frequency deviation estimation technique and suitable adjustment to obtain the Power system energy balance. This paper describes a digital signal processing technique for measuring the operating frequency of a power system. The fundamental frequency component of 3-phase signal is first extracted by using an algorithm based on FIR filter. The rate change of the phase angle is used for estimation. To confirm the validity of the proposed algorithm, the simulation studies carried out on a typical 154KV double T/L system by using EMTP software. Some test results are presented in the paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3145-3147
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• 2000

A passive RFID system consists of reader and tag. Reader is required the filter to modulate the data from backscattering signal which is transmitted by tag. The filter in the reader consists of envelope detector, amplifier, filter, and pulse shaping circuit, In this paper, design and analysis of filter in the RFID system which is operated at l3.56MHz carrier and 70KHz backscattering signal frequency is presented and is confirmed by simulation using Pspice.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.149-151
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• 2005

This paper deals with the novel control algorithm of single-phase hybrid active power filter for the compensation of harmonic current components in nonlinear R-L load with passive active power filters. To construct two-axes coordinate, an imaginary second phase was made by giving time delay to line current. In this proposed method, the new signal, which was the delayed through the filtering by the phase-delay property of low-pass filter, is used as the secondary phase. Because two phases have different phase, instantaneous calculation of harmonic current is possible. In this paper, a reference voltage is created by multiplying gain of filter by compensation current using the rotating reference frames that synchronizes with source-frequency, not applying to instantaneous reactive power theory which has been used with the existing fixed reference frames. This paper shows the experimental results, which provide a high accuracy and extremely fast response of single-phase hybrid active Bower filter under the operation with the proposed control method.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권8호
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• pp.377-386
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• 2005

This paper presents the control algorithm of single-phase hybrid active power filter for the compensation of harmonic current components in nonlinear R-L load with passive active Power filters. To construct two phase system, an imaginary second phase was made. In this proposed method, the new signal which is the delayed through the filtering by the phase-delay property of low-pass filter is used as the secondary phase. Because two-phases have the different phase, the instantaneous calculation of harmonic current is possible. In this paper, a reference voltage is created by multiplying the coefficient k by the compensation current using the rotating reference frame synchronized with the source-frequency, not applying to instantaneous reactive power theory which has been used with the existing fixed reference frames In order to verify the validities of the proposed control methods, experiments are carried out with the prototypes of single-phase hybrid active power filter.

• 정보통신설비학회논문지
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• 제4권1호
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• pp.31-36
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• 2005

In this paper, a planar type bandpass filter in multilayered PCB is presented. The multilayered PCB structure has some advantages on fabricating microwave devices such as the size reduction and ability of tight coupling by folding or embedding. The proposed BPF has two transmission zeros at the both sides of the center frequency by using independent electric and magnetic coupling structure. The designed BPF with four layer teflon PCBs of dielectric constant 2.94 has dimensions of 24x20x1.524 in mm, center frequency of 2.47GHz and bandwidth of about l00MHz. A good agrement is achieved between the measured result and the simulated one. The influences of air gaps between the layers are also analyzed and presented.