• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.125-132
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• 2002

PMSMS (permanent magnet synchronous motors) are widely used in industrial applications and home appliances because of their high torque to inertia ratio, superior power density, and high efficiency. For high performance control, accurate informations about the rotor position is essential. Sensorless algorithms have lately been studied extensively due to the high cost of position sensors and their low reliability in harsh environments. A novel position sensorless speed control for PMSMs uses indirect flux estimation and is presented in this paper. Rotor position and angular velocity are estimated by the proposed indirect flux estimation. Linkage flux and magnetic field flux are calculated by the voltage equations and the measured phase current without any integration. Instead of linkage flux calculation with integral operation, indirect flux and differential magnetic field are used for the estimation of rotor position. A proper rejection technique fur current noise effect in the calculation of differential linkage flux is introduced. The proposed indirect flux detecting method is free from the integral rounding error and linkage flux drift problem, because differential linkage flux can be calculated without any integral operation. Furthermore, electrical parameters of the PMSM can be measured by the proposed TCM (time compression method) for soft starting and precise estimation of rotor position. The position estimator uses accurate electrical parameters that are obtained from the proposed TCM at starting strategy. In the operating region, a proper compensation method fur temperature effect can compensate fir the estimation error from the variation of electrical parameters. The proposed novel position sensorless speed control scheme is verified by the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.204-206
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• 2002

For small capacity rectifier circuits such as these for consumer electronics and appliances. capacitor input type rectifier circuits are generally used Consequently. various harmonics generated within the power system become a serious Problem. Various studies of this effect have been presented previously. However. most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over -load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method. It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency. Hence, the harmonic characteristics can be significantly improved. where the lower order harmonics. such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and expermental implementations.

• 센서학회지
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• 제12권4호
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• pp.185-190
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• 2003

최근 적외선이나 초음파, 전자기파 등을 이용해 자연의 신호를 검출해 내는 센서들이 여러 가지 응용분야에서 널리 사용되고 있다. 더욱이 어떤 대상물이 가지고 있는 정보를 감지하는 고성능의 단일센서뿐만 아니라 이를 시스템적으로 개발하고 응용하는 것의 필요성도 높아져 왔다. 본 논문에서는 마이크로파를 이용한 레이더 센서 시스템을 설명하였고, 그 중 CW (Continuous Wave) 도플러 레이더를 이용한 마이크로파 센서 시스템의 동작 및 응용을 살펴보았다. 또한 이러한 시스템에 사용될 수 있는 고안정 주파수원으로 유전체 공진 발진기를 설계 제작하여 상용 시스템으로의 적용 가능성을 보였다. 제작된 유전체 공진 발진기는 12.67 GHz에서 동작하고, 출력전력이 +5.33 dBm 위상잡음은 100 kHz 옵셋주파수에서 -108.5 dBc/Hz를 얻었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1840-1842
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• 1998

Gyroscope is a very important core sensor, as a rotation sensor in inertial space, in inertial guidance and navigation system on aeronautics, plane, vessel and so on for civilian and millitary applications. Mechnical gyroscopes, adopting a principle of spinning a top, have been used in many application system. These mechnical gyroscopes need high power consumption, long warming time and complicated peripheral devices. But fiber-optic gyroscopes, based on the Sagnac effect, have novel advantages as small volume. simple scheme, low power consumption and high reliability. So we have developed a Intermediate grade All-fiber Optic Gyroscope, which has open-loop and minimum reciprocal configuration scheme. We have designed feedback circuits for stability of amplitude and phase using four lock-in amplifier(LIA) circuits and also used for noise limitation. This paper describes the scheme of optical part and electronic part and also test results of this all-fiber optic gyroscope. The performance have been achieved as long-term bias drift of $9.54^{\circ}/h$, random walk of $0.0317^{\circ}/\sqrt{h}$ and dynamic range of ${\pm}150\;deg/s$.

• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.229-235
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• 2012

This paper dealt with the fabrication of a partial discharge (PD) analyzer for insulation diagnosis of power facilities like transformers, cables and gas-insulated switchgears. An analytic algorithm for the phase (${\phi}$), the magnitude (q), and the pulse count (n) of PD pulse was designed and a time-frequency (TF) map algorithm was applied in the system to eliminate noises by analyzing the time and the frequency component of signals. All the algorithms were operated by a LabView graphical program. The detection circuit consists of a coupling capacitor, a detection impedance, and a low noise amplifier. A plane-plane and a point-plane electrode system were fabricated to simulate different types of insulation defects. In the experiment, we could easily understand the characteristics of PD pulses using the prototype PD analyzer.

• 센서학회지
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• 제16권6호
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• pp.475-483
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• 2007

This paper proposes a readout integrated circuit (ROIC) for $32{\times}32$ infrared focal plane array (IRFPA) detector, which consist of reference resistor, detector resistor, reset switch, integrated capacitor and operational amplifier. Proposed ROIC is designed using $0.35{\;}{\mu}m$ 2P-4M (double poly four metal) n-well CMOS process parameters. Low noise folded cascode operational amplifier which is a key element in the ROIC showed 12.8 MHz unity-gain bandwidth and open-gain 89 dB, phase margin $67^{\circ}$, SNR 82 dB. From proposed circuit, we gained output voltage variation ${\Delta}17{\};mV/^{\circ}C$ when the detector resistor varied according to the temperature.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권1호
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• pp.49-55
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• 2002

This paper presents high performance MEMS passives using fully CMOS compatible, monolithically integrable 3-D RF MEMS processes for RF and microwave applications. The 3-D RF MEMS technology has been developed and investigated as a viable technological option, which can break the limit of the conventional IC technology. We have demonstrated the versatility of the technology by fabricating various 3-D thick-metal microstructures for RF and microwave applications, such as spiral/solenoid inductors, transformers, and transmission lines, with a vertical dimension of up to $100{\;}\mu\textrm{m}$. To the best of our knowledge, we report that we are the first to construct a fully integrated VCO with MEMS inductors, which has achieved a low phase noise of -124 dBc/Hz at 300 kHz offset from a center frequency of 1 GHz.

• 전자공학회논문지S
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• 제35S권5호
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• pp.48-58
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• 1998

In this paper, we proposed a new algorithm using characteristics of th ereconstructed phase trajectory by topological mapping developed for a real-tiem detection of the QRS complexes of ECG signals. Using fill-factor algorithm and mutual information algorithm which are in genral used to find out the chaotic characteristics of sampled signals, we inferred the proper mapping parameter, time delay, in ECG signals and investigated QRS detection rates with varying time delay in QRS complex detection. And we compared experimental time dealy with the theoretical one. As a result, it shows that the experimental time dealy which is proper in topological mapping from ECG signals is 20ms and theoretical time delays of fill-factor algorithm and mutual information algorithm are 20.+-.0.76ms and 28.+-.3.51ms, respectively. From these results, we could easily infer that the fill-factor algorithm in topological mapping from one-dimensional sampled ECG signals to two-dimensional vectors, is a useful algorithm for the detemination of the proper ECG signals to two-dimensional vectors, is a useful algorithm for the detemination of the proper time delay. Also with the proposed algorithm which is very simple and robust to low-frequency noise as like baseline wandering, we could detect QRS complex in real-time by simplifying preprocessing stages. For the evaluation, we implemented the proposed algorithm in C-language and applied the MIT/BIH arrhythmia database of 48 patients. The proposed algorithm provides a good performance, a 99.58% detection rate.

• 한국통신학회논문지
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• 제25권9A호
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• pp.1306-1312
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• 2000

저궤도 관측위성에 탑재된 전자광학 카메라(Electro Optical Instrument)에서 생성되는 지상 표적의 영상데이터 (수 백 Mbps)를 실시간 지상 수신소로 전송하는 X-밴드 송신기에 대한 quality loss를 MC 방식의 시뮬레이션으로 산출하였다. 본 quality loss 시뮬레이션에는 QPSK 변조기의 데이터 비대칭(data asymmetry), I Q 채널간의 신호 크기 및 위상편차 불균형(unbalance), 채널결합기(OMUX)의 채널필터에 의한 변조파형 정형화 및 채널간섭 등의 변수가 포함되었다. 무선 구간의 잡음채널을 가산성 가우시안 백색잡음으로 가정할 때, 신뢰도 95 %를 기준한 시뮬레이션에서 X-밴드 송신기의 quality loss 0.7 dB를 구했으며, 이 quality loss는 데이터 링크의 링크버짓(link budget)에서 부가적인 손실항으로 반영되었다.

• 한국전자파학회논문지
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• 제16권4호
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• pp.345-350
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• 2005

본 논문에서는 저가형 구조에 이용 가능한 X-band 대역의 push-push형 VCO를 제안하였다. 제작된 push-push형 발진기는 부가적인 바렉터 다이오드를 사용하지 않고, 컬렉터 바이어스를 가변하여 X-band에서 넓은 주파수 가변을 얻었다. 측정 결과 컬렉터 바이어스 전압을 $4\~9V$ 가변하였을 때 $10.9\cal{GHz}\~11.8\cal{GHz}$의 $900\cal{MHz}$의 주파수 가변, $-30\;\cal{dBc}$ 이하의 우수한 $f_0$ 억압 특성, $-115\;\cal{dBc/Hz}\;@\;1\;\cal{MHz}$의 위상 잡음 특성을 가졌다.