• 대한한의학회지
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• 제29권2호
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• pp.60-70
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• 2008

Objectives: The aim of the present investigation was to determine whether the finger photoplethysmography (PPG) of the young will become analogous to those of the old when the PPG harmonic components in the young decrease. Methods: The PPG was measured in 46 old men (21 males and 25 females) over the age of 60 years and 10 young men (5 males and 5 females). We acquired the representative pulse waveform of old men by averaging the PPG waveforms measured in the old men. after the PPG harmonic components in the young men were diminished with notch filtering, we compared the representative pulse waveform of old men and those of the young men. Results: The PPG waveform of the young males became analogous to the representative pulse waveform of the old as the PPG harmonic components in the young were diminished with notch filtering. Especially after the second harmonic component in the young was diminished with notch filtering, increase of the Pearson's correlation coefficient was prominent. On the other hand, the Pearson's correlation coefficient between the PPG waveforms of the young females and that of the old deceased after the second harmonic component diminished in the young. Conclusions: Decrease of the second harmonic component may be a precondition of typical age-related change of the pulse waveform in the healthy male.

• 대한의용생체공학회:의공학회지
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• 제30권1호
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• pp.79-88
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• 2009

A harmonic quadrature demodulation method to extract the second harmonic component from focused ultrasound signals after a single transmit-receive event is proposed. In the proposed method, the focused ultrasound signal is converted into baseband inphase and quadrature components by multiplying with sine and cosine signals both having twice the center frequency of the transmitted signal and filtering the two modulated signals. The quadrature component is then passed through a Hilbert filter to be added to the inphase component, which leaves only the envelope of the second harmonic component. A novel phase estimation technique is employed in the proposed method to avoid the phase mismatch between the focused signal and the two modulating signals. The proposed method is verified through both theoretical analysis and computer simulations. It is shown that compared to the pulse inversion scheme the proposed method provides almost the same results for stationary targets and significantly improved harmonic to fundamental ratio for moving targets.

• 한국전자파학회논문지
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• 제23권5호
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• pp.624-631
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• 2012

본 논문은 Guanella의 1:1 transmission-line transformer와 harmonic filtering 방식을 이용한 13.56 MHz 고효율 전류 모드 D급(CMCD) 전력증폭기를 제안한다. 출력 정합 네트워크에 기존의 D급 전력증폭기의 부하 네트워크를 변형하여 harmonic filtering 방식을 포함시킴으로써 낮은 2차와 3차 고조파 특성을 얻었다. 제작된 CMCD 전력증폭기는 13.56 MHz의 CW 입력 신호를 사용하여 측정하였을 때, 13.4 dB의 전력 이득을 가지며, 44.4 dBm의 출력에서 84.6 %의 높은 PAE 특성을 나타내었다. 같은 출력에서 2차 3차 고조파는 각각 -50.3 dBc와 -46.4 dBc를 나타냈다.

• 대한한의진단학회지
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• 제11권2호
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• pp.1-12
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• 2007

Objectives: The aim of the present investigation was to determine whether the finger photoplethysmographic waveform of a healthy young man will become analogous to those of healthy old men when the photoplethysmographic harmonic components in the young man decrease. Methods and Results: The finger photoplethysgmoraphy was measured in 21 old men over the age of 60 years and a young men. We acquired the representative pulse waveform of old man by averaging the finger photoplethysmographic waveforms measured in the old men. after the photoplethysmographic harmonic components in the young man were diminished with notch filtering, we compared the representative pulse waveform of old man and the pulse waveforms of which the harmonic components decreased in the young man. The finger photoplethysmographic waveform of the young man became analogous to those of the old men as the photoplethysmographic harmonic components in the young man were diminished with notch filtering. Conclusions: Decrease of the second harmonic component may be a precondition of typical age-related change of the pulse waveform.

• 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.

• Journal of Power Electronics
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• 제17권5호
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• pp.1231-1243
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• 2017

Grid-interactive power converters are normally synchronized with the grid using phase-locked loops (PLLs). The performance of the PLLs is affected by the non-ideal conditions in the sensed grid voltage such as harmonics, frequency deviations and the dc offsets in single-phase systems. In this paper, a single-phase PLL is presented to mitigate the effects of these non-idealities. This PLL is based on the popular second order generalized integrator (SOGI) structure. The SOGI structure is modified to eliminate the effects of input dc offsets. The resulting SOGI structure has a high-pass filtering property. Hence, this PLL is termed as a high-pass generalized integrator based PLL (HGI-PLL). It has fixed parameters which reduces the implementation complexity and aids in the implementation in low-end digital controllers. The HGI-PLL is shown to have the lowest resource utilization among the SOGI based PLLs with dc cancelling capability. Systematic design methods are evolved leading to a design that limits the unit vector THD to within 1% for given non-ideal input conditions in terms of frequency deviation and harmonic distortion. The proposed designs achieve the fastest transient response. The performance of this PLL has been verified experimentally. The results agree with the theoretical prediction.

• Journal of electromagnetic engineering and science
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• 제9권1호
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• pp.25-31
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• 2009

This paper describes CMOS VCO circuit design procedures and techniques for multi-band/multi-standard RF transceivers. The proposed techniques enable a 4 GHz CMOS VCO to satisfy all requirements for Quad-band GSMIEDGE and WCDMA standards by achieving a good trade-off among important specifications, phase noise, power consumption, modulation performance, and chip area efficiency. To meet the very stringent GSM T/Rx phase noise and wide frequency range specifications, the VCO utilizes bond-wire inductors with high-quality factor, an 8-bit coarse tune capbank for low VCO gain(30$\sim$50 MHz/V) and an on-chip $2^{nd}$ harmonic noise filter. The proposed VCO is implemented in $0.13{\mu}m$ CMOS technology. The measured tuning range is about 34 %(3.17 to 4.49 GHz). The VCO exhibits a phase noise of -123 dBc/Hz at 400 kHz offset and -145 dBc/Hz at 3 MHz offset from a 900 MHz carrier after LO chain. The calculated figure of merit(FOM) is -183.5 dBc/Hz at 3 MHz offset. This fully integrated VCO occupies $0.45{\times}0.9\;mm^2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.127-128
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• 2006

The proposed differential LC cross-coupled VCO is implemented in InGap/GaAs HBT process for an adaptive Global Positioning system(GPS) application. Two filtering capacitors are used at the base of output buffer amplifiers at the both sides of the core m order to improve phase noise characteristics. The VCO produced a phase noise of -133 dBc/Hz at 3MHz offset frequency from the carrier frequency of 1.489GHz and the second harmonic suppression is significantly suppresed up to -49dBc/Hz in simulation result. The three pairs of BC diodes are integrated m the tank circuit to increase the VCO Tunning range.

• 한국전자파학회논문지
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• 제24권6호
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• pp.613-622
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• 2013

본 논문에서는 ISM 13.56 MHz 대역 무선 전력 전송을 위한 인덕티브 클램핑 class-E 전력증폭기를 설계 및 실험하여 특성을 분석하였다. 구현된 전력증폭기는 수신 안테나가 회전체에 붙는 경우와 같이 송수신 안테나 간의 정합 상태가 변화하는 시스템에서 부정합 상태에서 전력증폭기에 공급되는 전류를 줄여 트랜지스터를 손상시키지 않고 안정적으로 동작하도록 하는 인덕티브 클램핑 방식으로 설계되었으며, 정합 회로를 이용하여 기존의 class-E 전력증폭기보다 고조파 성분에 대한 Filtering 특성을 개선하였다. 구현된 전력증폭기의 입력 주파수는 13.56 MHz, 입력 전력 25 dBm, 동작 전압 DC 28 V에서 측정한 결과, 출력 전력은 43 dBm, 기본 주파수 성분과 2차 고조파 신호 간의 출력 전력 차이 55 dBc 이상, 소모 전류 830 mA으로 전력부가 효율(power added efficiency)은 85 %로 높게 측정됐다. 마지막으로, 수신 안테나를 회전체에 부착하고 구현된 전력증폭기로 송수신 안테나로 전력을 송출하는 실험을 진행하였으며, 송신 안테나의 부정합 상태에는 소모 전류가 420 mA까지 줄어들어 트랜지스터가 손상되지 않는 것을 확인하였다.