• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.179.3-179
• /
• 2001

This paper describes the dual system technology of PC based control system at steel plant. Because PC is developed to be used in wide area such as Office Automation, Personal, It is cheaper and more portable than the present process control system, but is less stable and less reliable. In this research, We gathered the fault example of a general process control system and steel process control system, analyzed the cause of fault and decided the target fault that took over in our proposed system. The proposed PC based system is the dual system that has a shared RAID system connected by SCSI bus between two systems. In order to assist system reliability, we proposed watchdog manager to monitor ...

• 한국기계가공학회지
• /
• 제11권4호
• /
• pp.154-159
• /
• 2012

Condition monitoring(CM) is a method based on Non-destructive test(NDT). Therefore, recently many kind of NDT were applied for CM. Acoustic emission(AE) is widely used for the early detection of faults in rotating machinery in these days also. Because its sensitivity is higher than normal accelerometers and it can detect low energy vibration signals. A machine tool consist of many parts such as the bearings, gears, process tools, shaft, hydro-system, and so on. Condition of Every part is connected with product quality finally. To increase the quality of products, condition monitoring of the components of machine tool is done completely. Therefore, in this paper, acoustic emission method is used to detect a machine fault seeded in a gearbox. The AE signals is saved, and power spectrums and feature values, peak value, mean value, RMS, skewness, kurtosis and shape factor, were determined through Matlab.

• 한국자동차공학회논문집
• /
• 제11권2호
• /
• pp.89-95
• /
• 2003

We consider a problem of application of analytical redundancy to engine synchronization process of spark ignition engines, which is critical to timing for every ECU process including ignition and injection. The engine synchronization process we consider here is performed using the pulse signal obtained by the revolution of crankshaft trigger wheel (CTW) coupled to crank shaft. We propose a discrete-time linear model for the signal, for which we construct FDI (Fault Detection & Isolation) system consisting residual generator and threshold based on linear observer.

• International Journal of Reliability and Applications
• /
• 제8권1호
• /
• pp.53-66
• /
• 2007

This paper proposes a new non-homogeneous Poisson process software reliability growth model based on the coverage information. The new model incorporates the coverage information in the fault detection process by assuming that only the faults in the covered constructs are detectable. Since the coverage growth behavior depends on the testing strategy, the fault detection process is first modeled for the general testing strategy and then realized for the uniform testing. Finally the model for the uniform testing is empirically evaluated by applying it to real data sets.

• Journal of Electrical Engineering and Technology
• /
• 제7권5호
• /
• pp.797-806
• /
• 2012

Fault detection and isolation (FDI) algorithms provide fault monitoring methods in GPS measurement to isolate abnormal signals from the GPS satellites or the acquired signal in receiver. In order to monitor the occurred faults, FDI generates test statistics and decides the case that is beyond a designed threshold as a fault. For such problem of fault detection and isolation, this paper presents and evaluates position domain integrity monitoring methods by formulating various pseudorange prediction methods and investigating the resulting test statistics. In particular, precise measurements like carrier phase and Doppler rate are employed under the assumption of fault free carrier signal. The presented position domain algorithm contains the following process; first a common pseudorange prediction formula is defined with the proposed variations in pseudorange differential update. Next, a threshold computation is proposed with the test statistics distribution considering the elevation angle. Then, by examining the test statistics, fault detection and isolation is done for each satellite channel. To verify the performance, simulations using the presented fault detection methods are done for an ideal and real fault case, respectively.

• 정보처리학회논문지C
• /
• 제9C권4호
• /
• pp.497-504
• /
• 2002

본 논문에서는 시스템의 네트워크 구성 장애를 관리하기 위한 관리 모델과 에이전트들 간의 협력을 통한 장애의 진단 및 복구 알고리즘을 제시하고 있다. 관리 모델에는 장애의 검출, 진단, 복구의 세 단계로 이루어지며 각각은 RBR(Rule-Based Reasoning)에 기반으로 하여 규칙기반 지식 데이터베이스에 있는 규칙을 이용하여 네트워크의 구성 장애를 진단하고 복구한다. 또한 관리 도메인 상의 네트워크에 분포하고 있는 여러 에이전트들 간의 협력을 통하여 시스템 단독으로는 해결할 수 없는 복잡한 문제를 해결하거나 네트워크의 상황까지 고려하여 진단하고 복구함으로써 효율적인 시스템의 네트워크 구성 관리 알고리즘을 제시하고 있다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제11권1호
• /
• pp.1-5
• /
• 2011

To enter next process control, numerous approaches, including run-to-run (R2R) process control and fault detection and classification (FDC) have been suggested in semiconductor manufacturing industry as a facilitation of advanced process control. This paper introduces a novel type of optical plasma process monitoring system, called plasma eyes chromatic system (PECSTM) and presents its potential for the purpose of fault detection. Qualitatively comparison of optically acquired signal levels vs. process parameter modifications are successfully demonstrated, and we expect that PECSTM signal can be a useful indication of onset of process change in real-time for advanced process control (APC).

• 한국정보처리학회논문지
• /
• 제7권8호
• /
• pp.2497-2504
• /
• 2000

이 논문에서는 웹 서버 장애 항목을 정의하고, 장애를 진단하기 위한 규칙 및 복구 방법을 INBANCA기법을 이용하여 제안하였다. 장애 항목으로 프로세스 장애, 서버 과부하, 인터페이스 장애, 구성 및 성능 장애를 정의하였으며, 각 장애 항목을 진단하기 위한 지식을 활성 네트워크기법을 적용하여 표현하고, 이를 시스템 레벨 장애 진단 생성규칙과 서비스 레벨에 진단 생성규칙으로 정형화하였다. 또한 사례기반의 웹 서버 장애 복구를 위한 복구 규칙 정의 및 사례 라이브러리 구축을 통하여 환경 변수에 적응적인 복구 메커니즘을 제안하였다. 그리고 제안한 장애 진단규칙 및 복구 메커니즘의 타당성을 증명하기 위한 장애 환경 구성 및 각 장애 환경에 대한 생성규칙 적용과 복구과정을 실험을 통하여 제시하였다. 이 논문에서는 기하 급수적으로 증가하는 웹 서버의 장애 관리를 위한 메커니즘을 제안함으로써 웹 서버 관리를 위한 관리자의 노력을 최소화하고, 지능적인 장애 관리를 위한 방법론을 제시하고자 한다.

• 한국정밀공학회지
• /
• 제17권12호
• /
• pp.107-114
• /
• 2000

Rollers and rolls in the continuous process systems are noes of key components that determine the quality of web products. The condition of rollers and rolls(ex. eccentricity wear) should be consistently monitored in order to maintain the process conditions (ex. tension, edge position) within a required specification. In this paper, a new diagnosis technique is suggested to detect the defect of rollers/rolls (ex. eccentricity, wear) based on frequency domain analysis of web tension signal. The kernel of this technique is to use the spectrum amplitude of tension signal which allows to identify the fault rollers/rolls and to also diagnose the degree of fault in corresponding rollers and rolls. The experimental results proved that the suggested diagnosis technique can be successfully used to identify the defect rollers and rolls as well as to diagnose the degree of the defect of those rollers. The suggested technique can be applied to monitor and diagnose the shape of rollers and rolls in various multi-span web transport systems.

• Smart Structures and Systems
• /
• 제14권3호
• /
• pp.377-395
• /
• 2014

Vibration-based fault detection and condition monitoring of rotating machinery, using statistical process control (SPC) combined with statistical pattern recognition methodology, has been widely investigated by many researchers. In particular, the discrete wavelet transform (DWT) is considered as a powerful tool for feature extraction in detecting fault on rotating machinery. Although DWT significantly reduces the dimensionality of the data, the number of retained wavelet features can still be significantly large. Then, the use of standard multivariate SPC techniques is not advised, because the sample covariance matrix is likely to be singular, so that the common multivariate statistics cannot be calculated. Even though many feature-based SPC methods have been introduced to tackle this deficiency, most methods require a parametric distributional assumption that restricts their feasibility to specific problems of process control, and thus limit their application. This study proposes a nonparametric multivariate control chart method, based on multiscale wavelet scalogram (MWS) features, that overcomes the limitation posed by the parametric assumption in existing SPC methods. The presented approach takes advantage of multi-resolution analysis using DWT, and obtains MWS features with significantly low dimensionality. We calculate Hotelling's $T^2$-type monitoring statistic using MWS, which has enough damage-discrimination ability. A bootstrap approach is used to determine the upper control limit of the monitoring statistic, without any distributional assumption. Numerical simulations demonstrate the performance of the proposed control charting method, under various damage-level scenarios for a bearing system.