• 경영과학
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• 제12권1호
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• pp.19-34
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• 1995

The objective of this paper is to present a framework for an expert system for fault diagnosis in an FMS (Flexible Manufacturing Systyem). First, a system is analyzed structurally and functionally, giving the relationships between the system's components. These relationships, represented by strata, are are then stored in a deep knowledge base (DKB). Next, the specific knowledge, represented by echelons, about the symptoms and their probable causes for each component is stored in a shallow knowledge base (SKB) in the form of rule. When the fault diagnosis process begins, it starts to search the DKB and then the SKB, which is called hybrid reasoning in artificial intelligence.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 춘계학술대회
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• pp.207-215
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• 2000

This study deals with the application of knowledge-engineering and a methodology for the assessment & measurement of reliability, availability, maintainability, and safety of industrial systems using fault-tree representation. A fuzzy methodology for fault-tree evaluation seems to be an alternative solution to overcome the drawbacks of the conventional approach(insufficient information concerning the relative frequences of hazard events). To improve the quality of results, the membership functions must be approximated based on heuristic considerations. The purpose of this Is to describe the knowlwdge engineering approach, directed to integrate the various sources of knowledge involved in a FTA.

• 대한안전경영과학회지
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• 제2권2호
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• pp.1-10
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• 2000

This study deals with the application of knowledge engineering and a methodology for the assessment and measurement of reliability, availability, maintainability, and safety of industrial systems using fault-tree representation. A fuzzy methodology for fault-tree evaluation seems to be an alternative solution to overcome the drawbacks of the conventional approach (insufficient information concerning the relative frequence of hazard events). To improve the quality of results, the membership functions must be approximated based on heuristic considerations. The purpose of this study is to describe the knowledge engineering approach, directed to integrate the various sources of knowledge involved in a FTA.

• 한국통신학회논문지
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• 제32권1B호
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• pp.22-30
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• 2007

본 논문에서는 분산 객체 관리의 편의성을 제공하고, 고장 발생시에도 안정된 서비스를 가능케 하는 고장포용 객체그룹(Fault-Tolerant Object Group, FTOG) 프레임워크를 제안한다. FTOG 프레임워크는 서비스 우선순위와 체크포인트 방법을 이용하여 두 가지의 고장 회복 방안을 제공하며 퍼지 기반의 부하 추론 과정을 통한 부하 분산을 수행하여 서비스 실행에서의 효율성을 높인다. 또한 가상의 홈네트워크 환경을 구성하고 FTOG 프레임워크를 적용하여 시뮬레이션을 통해 분산되어 있는 객체들의 관리 및 부하 분산 등 본 모델의 안정성 및 신뢰성을 검증하였다.

• Smart Structures and Systems
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• 제13권3호
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• pp.453-471
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• 2014

The fault diagnosis of rolling element bearings has drawn considerable research attention in recent years because these fundamental elements frequently suffer failures that could result in unexpected machine breakdowns. Artificial intelligence algorithms such as artificial neural networks (ANNs) and support vector machines (SVMs) have been widely investigated to identify various faults. However, as the useful life of a bearing deteriorates, identifying early bearing faults and evaluating their sizes of development are necessary for timely maintenance actions to prevent accidents. This study proposes a new two-layer structure consisting of support vector regression machines (SVRMs) to recognize bearing fault patterns and track the fault sizes. The statistical parameters used to track the fault evolutions are first extracted to condense original vibration signals into a few compact features. The extracted features are then used to train the proposed two-layer SVRMs structure. Once these parameters of the proposed two-layer SVRMs structure are determined, the features extracted from other vibration signals can be used to predict the unknown bearing health conditions. The effectiveness of the proposed method is validated by experimental datasets collected from a test rig. The results demonstrate that the proposed method is highly accurate in differentiating between fault patterns and determining their fault severities. Further, comparisons are performed to show that the proposed method is better than some existing methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.300-302
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• 2006

Middleware offers function that user application program can transmit data independently of network device. Connection management about network connection of module is important for normal service of module base personal robot. Unpredictable network disconnection is influenced to whole robot performance in module base personal robot. For this, Middleware must be offer two important function. The first is function of error detection and reporting about abnormal network disconnection. Therefore, middleware need method for network error detection and module management to consider special quality that each network device has. The second is the function recovering that makes the regular service possible. When the module closed from connection reconnects, as this service reports connection state of the corresponding module, the personal robot resumes the existing service. In this paper proposed method of network connection management for to support fault tolerant about network error of network module based personal robot.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.620-623
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• 2008

홈 네트워크 제어 서비스 환경에서는 외부요인에 의한 장애, 네트워크 장애, 장치의 장애 등에 의해 장애가 발생할 수 있다. 더욱이 사용자는 시스템 결함 관리와 같은 복잡한 시스템 관리를 직접하는 것을 원하지 않는다. 따라서 홈 네트워크를 구성하는 홈 기기에 대해 장애가 발생할 경우 자동으로 복구하는 시스템을 필요로 한다. 이를 위해 본 논문에서는 홈 네트워크 제어 시스템 상의 홈 기기들의 제어 로그의 설계와 관리, 장애 발생시점의 홈 기기의 서비스 내용을 분석하여 홈 기기의 서비스 연속성을 보장하기 위한 방법을 제시하고 구현한다.

• 대한안전경영과학회지
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• 제22권1호
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• pp.15-21
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• 2020

Industrial Motors diagnostic equipment is highly dependent on the automation system, so if there are defects in the automation equipment, it can only rely on the operator's intuitive judgment.To help with intuitive judgment, Park's Vactor Approach(PVA) represents the current signal as a pattern of circles, so it can tell if a fault occurs when the circle is distorted. However, the failure to judge the degree of distortion of the circle pattern is the basis of the fault, so it will face difficulties. In this paper, in order to compare the faults of PVA, the period of d-axis current of PVA pulsation was mastered, so that two phase differences occurred in the same signal source. Through experiments, it is confirmed that this is a 90 degree cross formation of PVA, which is convenient for judging from the vision that there is no fault, thus helping the operator to make intuitive judgment.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2134-2143
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• 2018

This work introduces a fault diagnosis method for transformer based on self-powered radio frequency identification (RFID) sensor tag and improved Hilbert-Huang transform (HHT). Consisted by RFID tag chip, power management circuit, MCU and accelerometer, the developed RFID sensor tag is used to acquire and wirelessly transmit the vibration signal. A customized power management including solar panel, low dropout (LDO) voltage regulator, supercapacitor and corresponding charging circuit is presented to guarantee constant DC power for the sensor tag. An improved band restricted empirical mode decomposition (BREMD) which is optimized by quantum-behaved particle swarm optimization (QPSO) algorithm is proposed to deal with the raw vibration signal. Compared with traditional methods, this improved BREMD method shows great superiority in reducing mode aliasing. Then, a promising fault diagnosis approach on the basis of Hilbert marginal spectrum variations is brought up. The measured results show that the presented power management circuit can generate 2.5V DC voltage for the rest of the sensor tag. The developed sensor tag can achieve a reliable communication distance of 17.8m in the test environment. Furthermore, the measurement results indicate the promising performance of fault diagnosis for transformer.

• 대한전기학회논문지:전력기술부문A
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• 제54권2호
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• pp.73-78
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• 2005

The management of technological systems will become increasingly complex. Safe and reliable software operation is a significant requirement for many types of system. So, with software fault tolerance, we want to prevent failures by tolerating faults whose occurrences are known when errors are detected. This paper presents a fault location algorithm for single-phase-to-ground faults on the teed circuit of a parallel transmission line using software fault tolerance technique. To find the fault location of transmission line, we have to solve the 3rd order transmission line equation. A significant improvement in the identification of the fault location was accomplished using the N-Version Programming (NVP) design paradigm. The delivered new algorithm has been tested with the simulation data obtained from the versatile EMTP simulator.