• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.109-112
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• 1995

This paper is a study on the detection of the significant point in ECG signal. ECG signal consists of two components; one is high frequency component to be detected and the other is low frequency component to be removed. AR model is appropriate for modelling and removing the low frequency component. AR model coefficients are updated by artificial neural network algorithm. We can remove the background noise(low frequency) by passing through the AR filter. The remaining signals which include high frequency noise are sent to the matched filter to pass only the signal which we want to extract. The template used in matched filter is updated adaptively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1234-1238
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• 2005

As the low power GPS signal is susceptible to interference, interference can seriously degrade the performance of GPS receiver. This paper designs a ANIEF(Adaptive Narrowband Interference Excision in Frequency domain) filter that removes narrow band interferences with low signal loss. This filter uses the pre-correlation technique and attempts to filter out the interference in the frequency domain. The interference excision performance of the designed filter is evaluated for various interferences using the ANIEF filter inserted GPS software receiver and the interference generator. Interferences considered in this paper are single-tone CWI(Continuous Wave Interference), multi-tones CWI, pulsed CWI, and swept CWI. The narrowband interference excision filter in frequency domain is very effective against various interferences and the strong interference with a simple structure. However, the signal power loss is unavoidable while transforming. In this paper, the hamming window and overlap technique are adopted to reduce the signal power loss. Finally, the interference excision performance and the reduced signal power loss of the ANIEF filter are shown.

• 전자공학회논문지
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• 제50권12호
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• pp.287-291
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• 2013

광섬유 격자소자(FBG)를 이용한 광섬유 수중 음향센서는 기존의 광섬유 센서가 지니고 있는 우수한 장점들을 지니고 있을 뿐만 아니라, PZT센서가 검출할 수 없는 저주파수(30Hz~300Hz)특성에서도 우수한 신호 감지효과를 지니고 있다. 실험에서 $1{\times}3$ 광 커플러 보다, 최근 개발된 hopper lenz WDM을 사용하여, 최대 19KHz까지 고감도 음파신호를 검출하고, 우수한 신호압축율과 초저주파수의 신호검출가능성을 보임에 따라, 정교한 신호해석과 군사용으로 사용될 수 있는 초저주파 신호 검출에 실용화를 기대 할 수 있으며, 센서 어레이(array)를 통하여 고감도 다중화로 발전될 수 있다.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.48-52
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• 2005

The research topic of super-RENS technology is shifting from the signal intensity (CNR; Carrier to Noise Ratio) to the signal uniformity (Jitter or bER). To achieve an uniform signal characteristics, it is important to reduce signal fluctuation in a super-RENS disc. In this study, we investigated the relation between signal fluctuation and low frequency noise (LFN), and analyzed LFN increase in recording and readout processes. It was found that signal fluctuation had a close relationship with the LFN. Also, it was found that the recorded mark shape such a bubble type and high readout power increased the LFN in recording and readout process of a super-RENS disc. So, using non-bubble type recording material and low super-resolution readout material, we markedly improved the LFN in a super-RENS disc.

• 한국음향학회지
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• 제9권3호
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• pp.48-55
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• 1990

2차 샘플링이 도플러 신호의 평균 주파수 측정에 미치는 영향에 대해서 분석을 하였다. 아나로그/디지탈 변환기(analogue-to-digital converter)의 샘플링 주파수를 낮추기 위해 수신 신호를 $4f_0$ 대신에 $4f_0$/5나 $4f_0$/9의 낮은 주파수로 샘플링에서 도플러 신호를 얻을 수 있다. ($f_0$는 송신 신호의 중심 주파수이다.) 일반적인 도플러 시스템에서처럼 수신 신호가 협 대역이면 낮은 샘플링 주파수로 인해 발생되는 평균 주파수의 측정에 대한 오차는 무시할 정도로 작다는 것을 컴퓨터 시뮬레이션과 실험을 통해 증명하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권11호
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• pp.512-515
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• 2003

This paper is to investigate how partial discharge pulse signal can flow in 6.6㎸ motor stator windings. Pulse propagation is experimentally analyzed in stator windings using a variety of frequency-domain techniques. The experiments were performed on two stator windings in the laboratory. Spectrum analyzer(9KHz to 3㎓) with tracking generator(100kHz to 3㎓) was used. Sweep time of the tracking generator was looms. The frequency spectrum of the response signal was detected by active FET probe(1㎓). The active FET probe has a flat amplitude response up to 1㎓ without high frequency attenuation. The stator winding acts as a low-pass filter below 600KHz, the high-frequency components being highly declined. The resonance peaks show about 1.1MHz and 2MHz in low frequency of No. 1 and No. 2 stator windings, respectively. This low-frequency range indicates that attenuation is low. The peaks of partial discharge magnitude show about 900MHz, 1.6MHz in No. 1 stator winding and about 800KHz, 1.4MHz in No. 2 stator winding.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.825-829
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• 2005

This paper presents an approach for designing a fuzzy logic-based adaptive SVC damping In controller for damping low frequency power oscillations. Power systems are often subject to low Frequency electro-mechanical oscillations resulting from electrical disturbances. Generally, power system stabilizers are designed to provide damping against this kind of oscillations. Another means to achieve damping is to design supplementary damping controllers that are equipped with SVC. Various approaches are available for designing such controllers, many of which are based on the concepts of damping torque and others which treat the damping controller design as a generic control problem and apply various control theories on it. In our proposed approach, linear optimal controllers are designed and then a fuzzy logic tuning mechanism is constructed to generate a single control signal. The controller uses the system operating condition and a fuzzy logic signal tuner to blend the control signals generated by two linear controllers, which are designed using an optimal control method. First, we design damping controllers for the two extreme conditions; the control action for intermediate conditions is determined by the fuzzy logic tuner. The more the operating condition belongs to one of the two fuzzy sets, the stronger the contribution of the control signal from that set in the output signal. Simulation studies done on a one-machine infinite-bus and a four-machine two-area test system, show that the proposed fuzzy adaptive damping SVC controller effectively enhances the damping of low frequency oscillations.

• 센서학회지
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• 제22권1호
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• pp.84-88
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• 2013

In this paper, the low price signal generator with capability of frequency high-resolution and variable sync pulse has implemented. It fulfils well the requirements for SS-OCT of the frequency resolution less than 1Hz, frequency stability of ${\leq}{\pm}0.5Hz$/10 min and variable sync pulse output timing. Through its performance test applied to wavelength swept laser, 120 nm sweeping range and 10 mW average optical power were obtained. This shows that the realized sine-wave generator can replace the commercial high cost and high performance signal generators employed by current SS-OCT systems.

• 한국안전학회지
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• 제6권2호
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• pp.21-30
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• 1991

In this paper, we study effect of waveness at the optical surface roughness measurement. In generally, waveness components cause errors in calculation of the roughness value of metal surface. We study about surface roughness signals In the frequency domain for separate two signal component of real roughness and waveness by digital signal processing methods. Thereafter, determine low and high Component of frequency spectrum. By this separating frequency value we design liner low and high pass filter which cutoff frequency is 1 Hz. After this process, converted each filtered spectrum by inverse discrete fourier transformation to time domain waveness and real roughness signals We calculate surface roughness value from filtered roughness signals. For evaluate this method, we use five specimens roughness signal which obtained from optical surface roughness measuring system in 3mm/s moving speed with 0.1 mm laser beam spot size As a result, we obtain more linerized roughness value than that of unfiltered roughness signals.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권6호
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• pp.768-776
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• 2014

Using a simplified high-frequency small-signal equivalent circuit model for BSIM3 MOSFET, the fully differential two-stage folded-cascode CMOS operational amplifier is analyzed to obtain its small-signal voltage transfer function. As a result, the expressions for dc gain, five zero frequencies, five pole frequencies, unity-gain frequency, and phase margin are derived for op amp design using design equations. Then the analysis result is verified through the comparison with Spice simulations of both a high speed op amp and a low power op amp designed for the $0.13{\mu}m$ CMOS process.