• Title/Summary/Keyword: 확률분포모델

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Model based Fault Detection and Diagnosis of Induction Motors using Probability Density Estimation (확률분포추정기법을 이용한 유도전동기의 모델기반 고장진단 알고리즘 개발)

  • Kim, Kwang-Su;Lee, Young-Jin;Song, Xian-Hui;Lee, Kwon-Soon
    • Proceedings of the KIEE Conference
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    • 2008.04b
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    • pp.171-173
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    • 2008
  • This paper presents stochastic methodology based fault diction and diagnosis algorithm for induction motor systems. First, we construct probability distribution model from healthy motors and then probability distribution for faulty motors is recursively calculated by means of the proposed probability estimation. We measure motor current with hall sensors as system state. The estimated probability is compared to the model to generate a residue signal which is utilized for fault detection and diagnosis, that is, where a fault is occurred. We carry out real-time induction motor experiment to evaluate efficiency and reliability of the proposed approach.

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Speech analysis using the Robust Time-Weighted Kalman filtering (시간가중치의 로버스트 칼만필터를 이용한 음성분석)

  • 최홍섭;안수길
    • The Journal of the Acoustical Society of Korea
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    • v.11 no.1E
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    • pp.73-78
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    • 1992
  • 시벼형 신호인 음성 신호의 분석에 칼만필터를 이용하였다. 일반적인 음성 분석은 프레임단위의 처리방법인 선형 예측 부호화 기법을 주로 이용하지만 음성의 시변 특성을 파악하는데에는 적절하지 못 하다. 따라서 순차적인 추정기법으로 많이 이용되는 칼만 필터를 음성 분석에 적용하였다. 또한 음성과 같은 시변신호에서는 과거 신호의 잡음의 분산값에 적당한 가중치를 부가하므로써 과거의 신호에 의해 서 현재의 추정값에 미치는 영향을 줄였으며 이를 음성의 천이 구간에서의 파라메타 추정에 사용하였 다. 그리고 음성신호 모델에서 생기는 모델링 오차는 일반적으로 백색 가우시안 잡음으로 가정하고 있 으나 이는 자음과 같은 무성음에서 특징 파라메타 푸정에는 오차가 적지만 모음등의 유성음에서는 음성 발생시의 여기신호인 펄스열에 의해서 많은 모델링 오차를 생기게 한다. 따라서 모델링 오차신호는 Non-Gaussian 확률분포로 가정한 후 로버스트 칼만 필터를 사용하여 합성으멩 대해 특징 파라메터를 추출하였다.

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Teleoperation of an Internet-Based Mobile Robot with Network Latency (데이터 전송 지연을 고려한 인터넷 기반 이동 로봇의 원격 운용)

  • 신직수;류은태;강근택;주문갑;이원창
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2004.10a
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    • pp.52-55
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    • 2004
  • 오늘날 필드버스(fieldbus), 인터넷 그리고 무선통신 등을 이용한 원격 제어 기술이 급격히 발달하고 있다. 그러나 이러한 원거리 네트워크 기반 제어는 데이터를 전송함에 있어서 지연이 불가피하며, 또한 이 지연이 일정하지 않은 문제점을 지니고 있다. 이러한 네트워크 지연은 시스템의 안정성이나 정확도에 영향을 미친다. 잘 논문에서는 네트워크상의 데이터 전송 지연을 고려한 이동 로봇의 원격 운용을 위해 TSK(Takagi-Sugeno-Kang) 퍼지 시스템을 이용하여 전송 지연의 확률 분포 함수와 네트워크 모델을 구하고 이를 전송 지연 예측 알고리듬에 적용하였다. 그리고 컴퓨터 시뮬레이션으로부터 제안된 알고리듬의 실효성을 검증하고, 기존의 예측 알고리듬과의 비교분석을 통하여 그 성능을 평가하였다.

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A Statistical Study of CMP Process in Various Scales (CMP 프로세스의 통계적인 다규모 모델링 연구)

  • 석종원
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.12
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    • pp.2110-2117
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    • 2003
  • A physics-based material removal model in various scales is described and a feature scale simulation for a chemical mechanical polishing (CMP) process is performed in this work. Three different scales are considered in this model, i.e., abrasive particle scale, asperity scale and wafer scale. The abrasive particle and the asperity scales are combined together and then homogenized to result in force balance conditions to be satisfied in the wafer scale using an extended Greenwood-Williamson and Whitehouse-Archard statistical model that takes into consideration the joint distribution of asperity heights and asperity tip radii. The final computation is made to evaluate the material removal rate in wafer scale and a computer simulation is performed for detailed surface profile variations on a representative feature. The results show the dependence of the material removal rate on the joint distribution, applied external pressure, relative velocity, and other operating conditions and design parameters.

An Performance Analysis of Queueing for Data Traffic Considering the Burstiness and Delay Characteristics in 3G Mobile Comm. Systems (3G 이동통신시스템에서 데이터 트래픽의 버스트성과 지연특성을 고려한 큐잉성능 분석)

  • 김창호;이명훈;이종규;최영민;임석구
    • Proceedings of the IEEK Conference
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    • 2003.07a
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    • pp.469-472
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    • 2003
  • 음성 중심의 기존 2G CDMA/PCS의 성능 및 용량을 분석하기 위한 트래픽 모델링에서는 시간당 평균 호 발생률, 발생 간격의 분포, 호 유지시간(Holding Time), 그리고 최번시(Busy Hour)를 결정하는 것이 주요 과제였으며, 이를 이용한 트래픽 엔지니어링은 음성호의 Blocking 확률과 지연시간을 최소화 하기위한 충분한 호 자원 확보에 중심을 두었던 것이 사실이다. 그러나 CDMA2000 1X 및 1xEV-DO/DV와 같은 3G 고속 데이터 이동통신 시스템에서의 패킷 데이터 트래픽의 특성은 자기 유사성(Self-similarity)이라는 성질을 가진다는 것은 잘 알려진 사실이다. 이와같은 고속 데이터 이동통신 시스템에서 요구되는 효율적인 망의 설계 및 디멘져닝을 위해서는 무엇보다도 데이터 트래픽의 주요 특성인 버스트함과 자기유사성이 반영된 모델 분석이 요구된다. 이러한 관점에서 본 논문에서는 데이터 트래픽의 자기유사성 및 큐잉 지연을 고려한 유효대역폭 산출식을 유도하여 시뮬레이션 결과와 비교 분석하였다.

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Lifetime Prediction of Existing Highway Bridges Using System Reliability Approach (실제 교량의 시스템 신뢰성해석에 기초한 수명예측)

  • Yang, Seung Ie
    • Journal of Korean Society of Steel Construction
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    • v.14 no.2
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    • pp.365-373
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    • 2002
  • In this paper, the system reliability concept was presented to predict the lifespan of bridges. Lifetime distribution functions (survivor functions) were used to model real bridges to predict their remaining life. Using the system reliability concept and lifetime distribution functions (survivor functions), a program called LIFETIME was developed. The survivor functions give the reliability of component at time t. The program was applied to an existing Colorado state highway bridge to predict the failure probability of the time-dependent system. The bridge was modeled as a system, with failure probability computed using time-dependent deteriorating models.

A Stochastic Analysis in Fatigue Strength of Degraded Steam Turbine Blade Steel (열화된 증기 터빈블레이드의 피로강도에 대한 확률론적 해석)

  • Kim, Chul-Su;Jung, Hwa-Young;Kim, Jung-Kyu
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.262-267
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    • 2001
  • In this study, the Reliability of degraded steam turbine blade was evaluated using the limited fatigue data. The statistical estimation of limited fatigue data implies that some unknown uncertainties which may be involved in fatigue reliability analysis. Therefore, an appropriate distribution in the fatigue strength was determined by the characteristic distribution - linear correlation coefficient, fatigue physics, error parameter. 3-parameter Weibull distribution is the most appropriate distribution to assume for infinite region. The load applied on the blade is mainly tensile. The maximum Von-Mises stress is 219.4 MPa at the steady state service condition. The failure probability($F_p$) derived from the strength-stress interference model using Monte carlo simulation under variable service condition is 0.25% at the 99.99% confidence level.

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Reliability Analysis in Fatigue Strength of Connecting Rod (커넥팅 로드의 피로강도에 대한 신뢰성 해석)

  • Kim, Cheol-Su;Lee, Jun-Hyeong;Kim, Jeong-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.10
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    • pp.1651-1658
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    • 2001
  • It is necessary to evaluate fatigue strength and reliability of the connecting rod which is core part in automotive engine to assure the high level of durability of automobile. For this purpose, the loading conditions in automotive engine is obtained by the dynamic analysis. Based on these results, the critical section was identified by the finite element analysis. The fatigue strength under constant amplitude was evaluated and the mean of the fatigue limit at R = -2.27 derived from the staircase method was 311.2MPa. And the failure probability( F$\sub$p/ ) derived from the strength-stress interference model is 0.0003% at the 99.99% confidence level and the mean factor of safety was 4.2.

A Nonsymmetric Model of Directional Probability Variation [DPV] for Tanks (전차동체의 피탄각 결정을 위한 비대칭 방향확률분포 모델)

  • 김의환;장원범;이대일
    • Journal of the military operations research society of Korea
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    • v.25 no.1
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    • pp.55-74
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    • 1999
  • In this study, a nonsymmetric model of directional probability variation (dpv), which is fundamental and conforms well to various moving situations of attacking tanks, is obtained based on the Whittaker's theory. It is shown that it produces the same expression of the probability density function as the Whittaker's under the special moving condition of an attacking tank. Using the derived dpvs, the probability densities for the various cases of some examples are calculated numerically to verify the derived formulas, and compared with other existing symmetrical distributions widely used to grasp characteristics of them. As a result, it is noted that the plots of the probability density function for various cases selected exhibit very different and useful behavioral features. Applying the results with respect to the every tank in the computer simulation of engagement between two tank forces, it is expected that more reasonable shot distributions can be given comparing with other existing symmetrical ones. The derived dpvs may be utilized to decide shot distribution of other weapon systems through small modification.

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Information Theoretic Approach to Middle Korean [ß] (정보이론 기반 중세국어 'ㅸ'의 음운론적 대립에 대한 연구)

  • Park, Sunwoo
    • Korean Linguistics
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    • v.79
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    • pp.63-89
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    • 2018
  • This study explores contrastive relation among voiced bilabial fricative [${\ss}$], voiceless bilabial stop [p] and glide [w] in Middle Korean consonant system based on Probabilistic Model. Preceding researches about voiced bilabial fricative [${\ss}$] proposed two influential arguments. One is voiced bilabial fricative [${\ss}$] was an independent phoneme, the other is it was not an independent phoneme but an allophone of voiceless bilabial stop [p] in Middle Korean. This study applies Probabilistic Phonological Relationship Model (PPRM) for solving the problem of dichotomy about contrastive and allophonic relations. The analysis result of the contrastive entropy by PPRM suggests that voiced bilabial fricative [${\ss}$] was just an allophone of voiceless bilabial stop [p] or glide [w] in Middle Korean. Comparing the entropies between [p] and other consonants with the entropies between [${\ss}$] and other consonants, a continuum defined in terms of entropy reveals that [${\ss}$] in Middle Korean was more allophonic than phonemic.