• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.352-355
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• 1995

In this paper, estimation error bounds of the optimal FIR (Finite Impulse Response) filter, which is proposed by Kwon et al.[1, 2], are presented in discrete-time systems with the model uncertainty. Performance bounds are here represented by the upper bounds on the difference of the estimation error covariances between the nominal and real values in case of the systems with the noise or model parameter uncertainty. The estimation error bounds of the discrete-time optimal FIR filter is compared with those of the Kalman filter via a numerical example applied to the simulation problem by Toda and Patel[3]. Simulation results show that the former has robuster performance than the latter.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.684-701
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• 2016

The Gaussian process model (GPM) is a flexible surrogate model that can be used for nonparametric regression for multivariate problems. A unique feature of the GPM is that a prediction variance is automatically provided with the regression function. In this paper, we estimate the safety margin of a nuclear power plant by performing regression on the output of best-estimate simulations of a large-break loss-of-coolant accident with sampling of safety system configuration, sequence timing, technical specifications, and thermal hydraulic parameter uncertainties. The key aspect of our approach is that the GPM regression is only performed on the dominant input variables, the safety injection flow rate and the delay time for AC powered pumps to start representing sequence timing uncertainty, providing a predictive model for the peak clad temperature during a reflood phase. Other uncertainties are interpreted as contributors to the measurement noise of the code output and are implicitly treated in the GPM in the noise variance term, providing local uncertainty bounds for the peak clad temperature. We discuss the applicability of the foregoing method to reduce the use of conservative assumptions in best estimate plus uncertainty (BEPU) and Level 1 probabilistic safety assessment (PSA) success criteria definitions while dealing with a large number of uncertainties.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.101-104
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• 2004

This paper addresses uncertainty issues encountered recently in measuring head vibration using the conventional 6-axis or 9-axis bite-bar Those conventional bite-bars are shown to present insufficient information to measure a complete 6 degree-of-freedom motion of head vibration. In order to overcome such limit, a theoretical measurement model that consists of four 3-axis linear accelerometers is suggested (Theoretical backgrounds presented in this paper shall have been addressed in the international congress of ICA 2004 in this April). It is shown to enable the direct measurement of three angular acceleration components and six angular velocity-dependent nonlinear terms. In audition to the three linear acceleration terms, those nine angular motion-dependent ones are found to make it possible to evaluate the general head vibration for a given position. To examine the feasibility of the proposed method, a newly designed 12-axis bite-bar was developed. Detailed experimental results obtained using the developed 12-axis bite-bar are illustrated in the presentation of this paper, which illustrates what amount of measurement accuracy provides. But, this paper provides more detailed experimental data and extended uncertainty factors.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.379-384
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• 2003

Noise is a problem in many electronic circuits and active control system. Arising from spuriously coupled noise from other circuits, it corrupts the signal of interest and introduces an uncertainty into information it contains. In this paper, re have researched noise characteristics of the inductive displacement sensor which has been designed. n first present basic concept and characteristics of magnetic field-coupled noise in the sensor output signal. Then, n are present relation noise and sensor performances. Finally, we concentrate low noise design of a sensor driver and a signal detection circuit.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1265-1267
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• 2006

현재 ISO 에서는 공구제조업체에서 해당 공구의 수전달 진동을 측정하여 제시하도록 하는 규격을 제정 중에 있으며, 이를 위해서는 공구에서 발생하는 진동과 영향을 평가하는 기술이 확보되어야 하며, 이 과정에서 측정 불확도 수준을 결정하는 것이 매우 중요하다고 하겠다. 본 연구에서는 동력 공구 작업시 작업자의 손으로 전달되는 진동을 측정하고 그 영향을 평가함에 있어서 발생할 수 있는 불확도를 분석하였다. 먼저, ISO 5349 규격을 적용함에 있어서 존재하는 불확도 인자들을 분류하고, 각 인자들이 어느 정도 수준의 불확도를 발생시키는지 시험을 통해서 확인하고 분석하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.685-688
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• 2004

This paper addresses the study on developing the angular vibration calibration system which requires the highly accurate measurement technique of the amplitude and period of an oscillating angular motion. Two developed models for the low and high frequency ranges are introduced and their main features are also compared. In addition to the angular vibration exciters, a new measurement method, referred to the 'equi-angle sampling method', is proposed and its theoretical backgrounds are introduced. The proposed method is shown to provide much less measurement uncertainty, compared the fringe counting method. Experimental results demonstrate what amount of angular vibration amplitude measurement uncertainty is improved by suing the proposed equi-angle sampling method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.834-838
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• 1992

Tracking performance depends on the quantity of the measurement data. In the Kalman-Bucy filter and other trackers, this dependence is well understood in terms of the measurement noise covariance matrix, which specifies the uncertainty in the value of measurement inputs. In this paper, we derived approximated error covariance matrix to evaluate the dependence of target detection probability and false alarm probability in the presence of uncertainty of measurement origin.

• 한국통신학회논문지
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• 제33권11A호
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• pp.1105-1116
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• 2008

Cognitive Radio(CR)는 실제로 사용하지 않는 주파수 대역을 스스로 찾아서 이용함으로써 스펙트럼 효율을 향상시킬 수 있는 기술이다. 현재 사용되지 않는 스펙트럼 대역과 우선사용자(primary user)에 의해 점유되는 대역들을 찾기 위한 스펙트럼 센싱(spectrum sensing)은 CR 시스템에서 중요한 기술의 하나라고 말할 수 있다. 지금가지 연구된 스펙트럼 센싱 방법 중 에너지 검출 방식은 계산의 복잡도가 낮고 비교적 쉽게 구현 할 수 있어서 일반적으로 널리 사용되는 방식이지만 몇 가지 문제점들을 가지고 있다. 특히 불확실한 잡음 전력이 존재하는 환경에서는 에너지 검출기의 성능이 감쇠되기 때문에 이를 해결하기 위해 슬라이딩 윈도우 기반 에너지 검출 기법을 제안하였다. 이 방식은 슬라이딩 윈도우를 이용하여 관심대역에서 신호와 잡음이 가진 에너지를 분리하고 잡음을 제외한 신호의 에너지를 계산해서 우선사용자 신호의 존재 여부를 판단한다. 컴퓨터 시뮬레이션 결과를 통해 제안하는 에너지 검출 기법이 기존의 에너지 검출 방식 보다 우수한 성능을 지닌 다는 것을 확인하였다.

• 전자공학회논문지
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• 제51권6호
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• pp.3-8
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• 2014

TV 대역에 나타날 수 있는 무선 마이크 신호를 검출하는 방안으로 전력 스펙트럼의 최대값을 시험 통계량으로 사용하는 방안이 최근 발표되었다. 이 방식은 시험 통계량을 임계값과 비교하여 우선 사용자의 유무를 판정하는데, 이때 임계값은 목표로 하는 오경보 확률뿐만 아니라 배경 잡음 전력 수준에 따라 달라진다. 따라서 잡음 전력에 대한 불확실성이 존재하는 경우 그로 인한 성능 저하가 발생할 수 있다. 이에 대한 해결책으로 본 논문은 전력 스펙트럼의 최대값과 최소값의 비율을 시험 통계량으로 사용하는 방식을 제안하고, 그 분석 결과를 제시하고자 한다.

• Structural Engineering and Mechanics
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• 제47권3호
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• pp.361-381
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• 2013

A Bayesian probabilistic method is proposed for online estimation of the process noise and measurement noise parameters for Kalman filter. Kalman filter is a well-known recursive algorithm for state estimation of dynamical systems. In this algorithm, it is required to prescribe the covariance matrices of the process noise and measurement noise. However, inappropriate choice of these covariance matrices substantially deteriorates the performance of the Kalman filter. In this paper, a probabilistic method is proposed for online estimation of the noise parameters which govern the noise covariance matrices. The proposed Bayesian method not only estimates the optimal noise parameters but also quantifies the associated estimation uncertainty in an online manner. By utilizing the estimated noise parameters, reliable state estimation can be accomplished. Moreover, the proposed method does not assume any stationarity condition of the process noise and/or measurement noise. By removing the stationarity constraint, the proposed method enhances the applicability of the state estimation algorithm for nonstationary circumstances generally encountered in practice. To illustrate the efficacy and efficiency of the proposed method, examples using a fifty-story building with different stationarity scenarios of the process noise and measurement noise are presented.