• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.357-360
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• 2000

In this paper, we want to implement a noise canceller by using FIR filter on DSP(Digital Signal Processor). The FIR filter was designed by Blackman window together with desired band width and center frequency. We adopt Motorola DSP56002 and Crystal CS4215 (A/D and D/A converter) for our purpose. we generate input sinusoidal signals and noises by differential equations and pseudo random sequences on DSP also. The input signal including sinusoidal and noise passes through the FIR filter. The FIR filer output is a sinusoidal signal with noise reduced.

• 한국공작기계학회논문집
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• 제14권2호
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• pp.96-103
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• 2005

The early detection of the bearing defects in rotating machinery is very important since the critical failure of bearing causes a machinery shutdown. However it is not easy to detect the vibration signal caused by the initial defects of bearing because of the high level of random noise. A signal processing technique, called the adaptive line enhancer(ALE) as one of adaptive filter, is used in this study. This technique is to eliminate random noise with little a prior knowledge of the noise and signal characteristics. Also we propose the optimal methods fir selecting the three main ALE parameters such as correlation length filter order and adaptation constant. Vibration signals f3r three abnormal bearings, including inner and outer raceways and ball defects, were acquired by Anderon(angular derivative of radius on) meter. The experimental results showed that ALE is very useful f3r detecting the bearing defective signals masked by random noise.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.951-960
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• 2016

Tower insulators in electric power transmission network play a crucial role in preserving the reliability of the system. Electrical utilities frequently face the problem of flashover of insulators due to pollution deposition on their surface. Several research works based on leakage current (LC) measurement has been already carried out in developing diagnostic techniques for these insulators. Since the LC signal is highly intermittent in nature, estimation of pollution severity based on LC signal measurement over a short period of time will not produce accurate results. Reports on the measurement and analysis of LC signals over a long period of time is scanty. This paper attempts to use Random Forest (RF) classifier, which produces accurate results on large data bases, to analyze the pollution severity of high voltage tower insulators. Leakage current characteristics over a long period of time were measured in the laboratory on porcelain insulator. Pollution experiments were conducted at 11 kV AC voltage. Time domain analysis and wavelet transform technique were used to extract both basic features and histogram features of the LC signal. RF model was trained and tested with a variety of LC signals measured over a lengthy period of time and it is noticed that the proposed RF model based pollution severity classifier is efficient and will be helpful to electrical utilities for real time implementation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.228-232
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• 2004

This paper is to identify the position of random disturbance on flexible dynamic system, and the position of the piezo ceramic actuator 0 minimize tip response. Correlation of the output signals from each parts on flexible system is used to identify the position of random disturbance. Except the correlation with an output signal from the position of random disturbance, other correlations have time delay. This is a base idea to identify the position on this study.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제9권1호
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• pp.9-16
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• 2005

The random signals defined as sums of the single frequency sinusoidal signals with random amplitudes and random phases or equivalently sums of functions obtained by adding a Sine and a Cosine function with random amplitudes, are used in the double randomization method for the Monte Carlo solution of the turbulent systems. We show that these random signals can be used for studying the properties of the Johnson noise by proving that constant multiples of these signals with uniformly distributed frequencies in a fixed frequency band satisfy the properties of the Gaussian white noise.

• 전력전자학회논문지
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• 제10권5호
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• pp.501-507
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• 2005

본 연구에서는 유도 전동기의 파워 스펙트럼 확산을 위한 LF2407 DSP기반 하이브리드 랜덤 PWM(HRPWM)을 제안하였다. 제안된 방법은 Lead-Lag 랜덤 비트를 갖는 PRBS (Pseudo-Random Binary Sequence)와 논리적으로 비교를 하기 위한 랜덤 삼각파 캐리어로 구성된다. 또한 DSP에 의하여 랜덤 수 및 PRBS 그리고 3상 기준 정현파를 실시간으로 발생하며, DSP외부의 주파수 변조기 MAX038에 의하여 랜덤 주파수의 캐리어를 발생한다. 본 연구의 타당성 검증을 위하여 제안된 기법을 3상 가변속 구동장치에 적용하였으며, 종전의 방법과 전압 및 전류 그리고 전동기 소음의 파워 스펙트럼을 비교 검토하였다.

• Journal of information and communication convergence engineering
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• 제16권1호
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• pp.6-11
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• 2018

It is important to find the random estimation points in wireless sensor network. A link quality indicator (LQI) is part of a network management service that is suitable for a ZigBee network and can be used for localization. The current quality of the received signal is referred as LQI. It is a technique to demodulate the received signal by accumulating the magnitude of the error between ideal constellations and the received signal. This proposed model accepts any number of random estimation point in the network and calculated its nearest anchor centroid node pair. Coordinates of the LQI sphere are calculated from the pair and are added iteratively to the initially estimated point. With the help of the LQI and weighted centroid localization, the proposed system finds the position of target node more accurately than the existing system by solving the problems related to higher error in terms of the distance and the deployment of nodes.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.606-609
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• 2003

MOSFET의 1/f 잡음은 개별 Random Telegraph Signal (RTS)의 중첩에 의해 생성되는 것으로 알려져 있다. 본 연구에서는 CMOS 링 발진기 노드 중 하나에 RTS 전류원을 병렬로 연결하여 1/f 잡음에 의한 jitter를 분석하였다. 링 발진기의 숫자, 전원 전압, 그리고 RTS 진폭에 따른 litter rate 변화를 시뮬레이션을 통하여 분석하였다.

• Structural Engineering and Mechanics
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• 제40권6호
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• pp.745-762
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• 2011

Damage detection methodologies based on the direct examination of the nonlinear-nonstationary characteristics of the structure dynamic response may play an important role in online structural health monitoring applications. Different signal processing based damage detection methodologies have been proposed based on the uncovering of spikes in the high frequency component of the structural response obtained via Discrete Wavelet transforms, Hilbert-Huang transforms or high pass filtering. The performance of these approaches in systems subjected to different types of excitation is evaluated in this paper. It is found that in the case of random excitations, like earthquake accelerations, the effectiveness of such methodologies is limited. An alternative damage detection approach using the Continuous Wavelet Transform (CWT) is also evaluated to overcome this limitation. Using the CWT has the advantage that the central frequencies at which it operates can be defined by the user while the frequency bands of the detail functions obtained via DWT are predetermined by the sampling period of the signal.

• 방송공학회논문지
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• 제6권1호
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• pp.13-20
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• 2001

본 논문에서는 켑스트럼 영역에서의 오디오 워터마킹 방법을 제안한다. 광대역 채널에 협대역 신호를 숨기는 대역확산(spread spectrum) 통신과 유사한 방법을 이용하여 워터마크 신호를 오디오 신호의 켑스트럼 성분에 삽입한다. 의사잡음 시퀸스 (pseudo-random sequence)를 이용하여 오디오 신호에 삽입할 워터마크 신호를 발생시킨다 켑스트럼 계수들의 분포와 인간 청각 시스템(Human Auditory System, HAS)의 주파수 마스킹 특성을 고려하여 결정한 가중치를 곱해서 얻은 워터마크 신호는 사람 의 귀로 감지할 수 없을 정도의 크기를 갖는다. 본 논문의 실험 결과에서 보인 것처럼. 오디오 신호의 사용 권한이 없는 사용자들 은 삽입된 워터마크 신호를 검출하기가 통계적으로 거의 불가능하며, 다중 워터마크, MPEG 오디오 부호화. 부가잡음과 같은 다양한 공격에도 소유자에 의해서는 워터마크 신호의 검출이 가능하다.