• 센서학회지
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• 제25권1호
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• pp.71-78
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• 2016

PPG signal measured by pulse oximeter can measure pulse and the oxygen saturation of arterial blood. But the PPG signal is distorted by finger movement or other movement in the body. To detect pulse from the PPG signal with motion artifact, we use band pass filter(BPF), Independent component analysis(ICA) and nonlinear autocorrelation(NAC). BPF is used to remove DC component and high frequency noise in the PPG signal with motion artifacts. ICA is used to separate pulse signal and motion artifact. However, pulse signal separated by ICA have no choice but to accompany signal distortion because pulse signal and motion artifact are not completely independent. So, we use nonlinear autocorrelation to emphasize the pure pulse signal from the distorted signal.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.255-258
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• 1996

This paper describes a DC voltage controller for the DC power supply which is constructed using the full-bridged MOS-FET DC-to-RF power inverter and rectifier. The full-bridged MOS-FET DC-to-RF inverter consisting of four MOSFET arrays and an output power transformer has a control function which is able to control the RF output power when the widths of the pulse voltages which are fed to four MOS-FET arrays of the fall-bridged inverter are changed using the pulse width control circuit. The power conversion efficiency of the full-bridged MOS-FET DC-to-RF power inverter was approximately 85 % when the duty cycles of the pulse voltages were changed from 30 % to 50 %. The RF output voltage from the full-bridged MOS-FET DC-to-RF inverter is fed to the rectifier circuit through the output transformer. The rectifier circuit consists of GaAs schottky diodes and filters, each of which is made of a coil and capacitors. The power conversion efficiency of the rectifier circuit was over 80 % when the duty cycles of the pulse voltages were changed from 30 % to 50 %. The output voltage of the rectifier circuit was changed from 34.7V to 37.6 V when the duty cycles of the pulse voltages were changed from 30 % to 50 %.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.255-259
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• 2015

We have proposed and experimentally verified a pulse-width modulation (PWM) generator which directly generated a PWM signal in the optical domain. Output waveforms were clear at the repetition rate of 16 MHz; the duty cycle (DC) was from 14.7% to 72.1%; and the DC-control resolution was about 4.399%/dB. The PWM generator' operation principle is based on the injection-locking property of a single-mode Fabry-$P{\acute{e}}rot$ laser diode (SMFP-LD). The SMFP-LD, which has a self-locked mode wavelength at ${\lambda}_{PWM}$, was used to detect the power of the injection-locking signal (optical analog input). If the analog input power is high, the SMFP-LD is locked to the wavelength of the input signal ${\lambda}_a$ and there is no output after an optical bandpass filter (OBF). If the analog input power is low, the SMFP-LD is unlocked and there is output signal at ${\lambda}_{PWM}$ after the OBF. Thus, the SMFP-LD plus the OBF provide digital output for an analog input. The DC of the output PWM signal can be controlled by tuning the power of the analog input.

• 조명전기설비학회논문지
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• 제17권1호
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• pp.94-102
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• 2003

본 논문은 고주파 전원에 사용되는 풀 브릿지 부하 병렬형 고주파 공진 인버터 회로를 연구대상으로 하고 출력제어기법으로는 펄스 주파수 변조(PFM, 펄스 폭 변조(PWM) 그리고 펄스 위상 변화(Phase-Shift)잎 경우를 비교 검토하였다. 회로의 해석은 정규화 파라메타를 도입하여 범용성 있게 기술하였고, 인버터 특성은 3가지 구동신호패턴에 의한 스위칭 주파수($\mu$), 펄스폭($\theta$d), Phase-Shift의 위상차각($\phi$)의 변화와 제 파라메타에 따라 특성 평가를 행하였다. 실험을 통해 이론해석의 타당성을 검증하였다. 향후, 3가지의 구동신호제어기법에 의한 특성들은 유도가열 응용, DC-DC 컨버터 등의 전원 시스템의 출력제어 시에 유용한 자료로 제공될 것으로 사료된다.

• 한국정보통신학회논문지
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• 제4권3호
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• pp.575-583
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• 2000

펄스 옥시메터는 수술실, 회복실, 집중 치료실 등에서 사용되는 산소포화도($SpO_2$)를 측정하는 방법 중 광흡수도를 이용하여 비관혈적인 방법으로 산소포화도륵 측정하는 장비이다. 펄스 옥시메터는 동맥혈의 광흡수도를 측정함으로써 혈액의 산소포화도를 나타낼 수 있다. 산소포화도를 측정하는 기존의 방법은 잡음을 제거하는 필터링 기술과 복잡한 처리 알고리즘, 그리고 많은 연산 수행 시간을 필요로 한다. 본 연구에서는 신호 검출 단계에서 적색광과 적외선광 각각의 AC 성분과 DC 성분을 분리하여 처리함으로써, 연산 알고리즘을 단순화 할 수 있었다. 그리고 시스템을 구현한 결과 기존의 방법(로그연산법, 미분법) 보다 속도향상과 0.3% 이상의 성능개선을 보였다.

• Journal of Biosystems Engineering
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• 제25권5호
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• pp.351-358
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• 2000

This study was conducted to develop a speed control system of a DC motor which drove a barley seeder mounted on a combine harvester. Barley seeder mounted on a combine has been known to reduce labor and cost of barley cultivation. However, development of the seeder has been unsuccessful because the combine, a dedicated rice and barley harvester has not enough space and proper power take-off for barley seeder. To develop a barley seeder, small powered motor speed controller was required. A proximity sensor for detecting working speed of the combine and a programmable one board microprocessor was used to develope a control system. Motor parameters and motor constant, relationship between seeding rate, motor speed, groove volumes of a tested roller, torque were measured. The proximity sensor sent a frequency signal to the microprocessor. In laboratory experiments, the excitation voltage of the motor was shown not to be proportional to the size of pulse width (duty ratio). A table transforming frequency signal, that represented for working speed to proper pulse width was developed from seeding rate experiments. However, seeding rate at low frequency signal was not proportional to the working speed. Seeding rate control proportional to the frequency signal was achieved by shifting of the frequency signal.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.117-120
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• 2000

Pulse oximetry is a well established non-invasive optical technique for monitoring the SpO$_2$ during anaesthesia, recovery and intensive care. Pulse oximeters determine the oxygen saturation level of blood by measuring the light absorption of arterial blood. The sensors consists of red and infrared light sources and photodetectors. In the measurement of the hemoglobin oxygen saturation, conventional method has required the technique of filtering of remove the noise, and of complex signal processing algorithm. So much time have required to signal processing. In this research, we separate AC signal and DC signal in the stage of signal detection. We filter the noise from each signal and convert A/D. We obtain the SpO$_2$ using the DSP algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.313-315
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• 2009

In this thesis, A methodology of system implement for PID controller, PWM logic, HSC logic, Host Communication and external DAC interface are implemented into single FPGA chip is proposed. The implemented system is used to control the speed of DC servo motor. A DATA block transfers set point value(SV) and P, I, D gain parameters to the corresponding Blocks respectively by the Host Communication to Computer. A HSC block generates process value(PV) by a pulse and $90^{\circ}$ shifted pulse from the encoder A PID block makes error(E) signal from the set value and process value and output manufacture value(MV) through the PID controller. In PWM block using the MV from the PID block, drives H-bridge controlling the Motor. Also DAC interface controls the DAC to graph the digital signal such as SV, PV, E, MV in FPGA onto the Oscilloscope.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.43-46
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• 2007

In this paper, a novel new pulse power generator based on IGBT stacks is proposed for pulse power application. Proposed scheme consists of series connected 9 power stages to generate maximum 60kV output pulse and one series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 850VDC pulse. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is important for series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used. Proposed scheme has lots of advantages such as long lifecyle, compact size, flat topped pulse forming, small weight, protection for arc, high efficiency and flexibility to generate various kinds of pulse output.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.917-918
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• 2006

In this paper, a novel new pulse power generatorbased on IGBT stacks is proposed for pulse power application. Proposed scheme consists of series connected 9power stages to generate maximum 60kV output pulse and one series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 850VDC pulse. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is importantfor series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used.