• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.925-928
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• 1999

A multi-channel gas leakage monitoring system was designed and fabricated by using CPLD(complex Programmable Logic .Device) for monitoring and controlling the leakage of natural gas from supplying-pipes under the ground. Fabricated SnO$_2$thick film gas sensor elements were attached on safeguard steel plate of natural gas supplying pipes, and the local monitoring system in this study received the signal from the gas sensors. The monitoring system was implemented by using CPLD chip to reduce the development time and implement simple one chip system. The time division multi-channel system received the input signal from individual gas sensor at one of divided times by multiplexor and signal processed sequentially. The system reduced the size of peripheral circuit resulted in implementation of creditable simple system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.191-192
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• 2008

We give new definition of the effective-leakage and the signal to effective-leakage plus noise ratio (SELNR) to consider receiver combining motivated by the leakage. We propose a method to find jointly beamforming vector and combining vector for the two linear receivers (maximal ratio combining (MRC) receiver and minimum mean square error (MMSE) receiver) based on the SELNR.

• 한국통신학회논문지
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• 제41권8호
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• pp.859-867
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• 2016

GPS(Global Positioning System)는 미국에서 군사목적으로 이용하기 위해 개발된 위치측정 시스템으로, 현재는 우리나라를 포함한 각 국에서 군용뿐만 아니라 민간에도 유용하게 쓰이고 있다. 하지만 GPS는 위성으로부터 지면에 도달하는 신호의 세기가 매우 약해서 전파방해신호(Jamming Signal)에 약하다는 단점을 가진다. 본 논문에서는 수신된 GPS 신호에 협대역의 전파방해 신호가 존재한다고 가정하고, 새로운 협대역 전파방해신호 제거 알고리즘을 제안한다. 우선, GPS 수신기에서 수신한 신호를 FFT를 이용하여 주파수 성분으로 표현하며, FFT로 인하여 발생하는 Spectral Leakage의 영향을 줄이기 위하여 Blackman-Harris window를 적용한다. Blackman-Harris window의 주파수 응답을 형태를 이용하여, 가장 큰 파워를 가지는 주파수 성분을 찾고 그 주변으로 일정한 개수의 성분을 제거하는 알고리즘을 제안하였다. 주로 쓰일만한 128~512포인트의 FFT를 사용할 시에 고정적으로 최대값 주변의 42개의 성분을 제거하는 것이 가장 최적임을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1677-1688
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• 2020

In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.

• Journal of Mechanical Science and Technology
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• 제15권2호
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• pp.232-238
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• 2001

Fast Fourier Transformation is employed to convert the head variation of a pipeline in the time domain to the amplitude of the frequency domain. Applying method of characteristics to a pipeline provides a significant frequency range for a surge introduced from the valve modulation. Inverse Fast Fourier Transformation and a Finite Impulse Response Filter can be used to remove any possible noise existing from the significant frequency range of an unsteady condition. A filtered signal shows higher potential for the inverse calculation of leakage detection than the noise-added signal does. The respective performances of Inverse Fast Fourier Transformation and a Finite Impulse Response Filter are compared in terms of leakage detection capability. Characteristics of the frequency range for multiple leakages were investigated to validate the effectiveness of the noise control method in the frequency domain.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.1189-1194
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• 2002

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent micrphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidally have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional r]n analyzer will show distorted value. In this paper the expression of the Fourier transformed data of a harmonic signal is formulated when there is leakage error. The method to elimate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• 한국산학기술학회논문지
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• 제6권5호
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• pp.373-377
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• 2005

본 논문에서는 반도체 제조장비의 챔버 내부 가스누출을 방지하기위한 보완모듈을 제시하였다. MFC(mass flow controller) 다음단의 최종밸브와 챔버 사이의 가스관에 압력센서를 부착시켜, 압력센서의 신호와 최종밸브의 동작신호를 디지털 회로를 이용하여 실시간으로 감지하고 가스누출을 방지하도록 하였다. LED 모듈을 이용하여 공정중에 발생하는 2차 소성물로 인한 가스의 흐름과 관련된 시스템 고장을 표시한다. 본 연구에서 개발한 모듈을 이용하면 챔버 내에서의 가스누출로 인한 장비의 손상과 안전사고 등을 예방하는 효과가 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1156-1161
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• 2001

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent microphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidally have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional FFT analyzer will show distorted value. In this paper, the expression of the Fourier transformed date of a harmonic signal with a single frequency is formated when there is leakage error. The method to elimate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• Journal of Magnetics
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• 제18권3호
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• pp.357-360
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• 2013

A modified SQI method using magnetic leakage flux (MFL) signal for underground gas pipelines' defect detection and characterization is presented in this paper. Raw signals gathered using MFL signals include many unexpected noises and high frequency signals, uneven background signals, signals caused by real defects, etc. The MFL signals of defect free pipelines primarily consist of two kinds of signals, uneven low frequency signals and uncertain high frequency noises. Leakage flux signals caused by defects are added to the case of pipelines having defects. Even though the SQI (Self Quotient Image) is a useful tool to gradually remove the varying backgrounds as well as to characterize the defects, it uses the division and floating point operations. A modified SQI having low computational complexity without time-consuming division operations is presented in this paper. By using defects carved in real pipelines in the pipeline simulation facility (PSF) and real MFL data, the performance of the proposed method is compared with that of the original SQI.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.945-964
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• 2014

In this paper, we investigate the performance of Signal to Leakage and Noise Radio (SLNR) based user scheduling in uplink of multi-cell with large-scale antenna system. Large antenna array is desired to improve the performance in future system by providing better beamforming capability. However, some studies have found that the signal channel is 'hardened' (becomes invariant) when the antenna number goes extremely large, which implies that the signal channel aware user scheduling may have no gain at all. With the mathematic tool of order statistics, we analyzed the signal and interference terms of SLNR in a homogeneous multicell network. The derived distribution function of signal and interference shows that the leakage channel's variance is much more influential than the signal channel's variance in large-scale antenna regime. So even though the signal channel is hardened, the SLNR-based scheduling can achieve remarkable multiuser diversity (MUD) gain due to the fluctuation of the uplink leakage channel. By providing the final SINR distribution, we verify that the SLNR-based scheduling can leverage MUD in a better way than the signal channel based scheduling. The Monte Carlo simulations show that the throughput gain of SLNR-based scheduling over signal channel based scheduling is significant.