• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.932-935
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• 2002

In this paper, we introduce new FTL(Flash Translation Layer) driver algorithm that tolerate the power off errors. FTL driver is the software that provide the block device interface to the upper layer software such as file systems or application programs that using the flash memory as a block device interfaced storage. Usually, the flash memory is used as the storage devices of the mobile system due to its low power consumption and small form factor. In mobile system, the state of the power supplement is not stable, because it using the small sized battery that has limited capacity. So, a sudden power off failure can be occurred when we read or write the data on the flash memory. During the write operation, power off failure may introduce the incomplete write operation. Incomplete write operation denotes the inconsistency of the data in flash memory. To provide the stable storage facility with flash memory in mobile system, FTL should provide the fault tolerance against the power off failure. SSR (Simple Sector Remapper) is a fault tolerant FTL driver that provides block device interface and also provides tolerance against power off errors.

• 한국통신학회논문지
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• 제29권10A호
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• pp.1113-1122
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• 2004

분산 컴퓨팅 기술 발달과 인터넷 이용의 확산에 따라 고속의 멀티미디어 서비스에 대한 사용자의 욕구가 날로 증가하고 있다. 이에 따라 영상, 음성 등이 포함된 대용량 정보매체를 다루는 서비스가 주로 이루어지고 있으며 망 사업자들은 이러한 대용량 정보매체의 고속 전송이 가능하도록 초고속 네트워킹 설비에 끊임없이 투자하고 있다. 이와 같은 빠른 속도의 서비스뿐만 아니라 이와 동시에 만족되어야 하는 서비스의 요건은 안정성이다. 시스템 고장으로 인하여 기반 시설이 마비될 수 있는 전자 정보 시스템은 매우 높은 가용성 및 신뢰성을 가져야 한다. 이러한 고가용성과 고신뢰성을 얻기 위하여 본 논문에서는 핫 스탠바이 스페어링 기법을 이용한 고장 감내 다중화 시스템을 제안하고 구현한다. 제안된 시스템은 일반적인 단일 모듈 시스템을 다중화 하여 고장이 발생하면 유연하게 대처하도록 하고 고장 검출 버스를 적용하여 비교를 통한 고장 검출 기능이 가능하도록 하였다. 또한 제안된 구조는 단일 모듈 시스템에 버스 변환 장치를 도입하여 보다 쉽게 고장 감내 다중화 시스템을 구현할 수 있도록 하였다. 그리고 본 논문에서 제안한 하드웨어 시스템의 성능 평가를 위하여 마코프 프로세스를 이용한 모델링을 적용하여 고가용성 및 고신뢰성을 검증하였다.

• 제어로봇시스템학회논문지
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• 제15권7호
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• pp.753-759
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• 2009

As many systems depend on electronics in an intelligent vehicle, concern for fault tolerance is growing rapidly. For example, a car with its braking controlled by electronics and no mechanical linkage from brake pedal to calipers of front tires(brake-by-wire system) should be fault tolerant because a failure can come without any warning and its effect is devastating. In general, fault tolerance is usually designed by placing redundant components that duplicate the functions of the original module. In this way a fault can be isolated, and safe operation is guaranteed by replacing the faulty module with its redundant and normal module within a predefined interval. In order to make in-vehicle network fault tolerant, this paper presents the concept and design methodology of an IEEE 1451 based dual CAN module. In addition, feasibility of the dual CAN network was evaluated by implementing the dual CAN module.

• Journal of Power Electronics
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• 제11권6호
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• pp.824-836
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• 2011

A new fault-tolerant control topology for open-loop motor-drive systems with Delta-connected stator windings is introduced in this paper. This new control topology enables the operation of a three-phase induction machine as a two-phase machine fed by a three-phase inverter upon a failure in one of the motor phases. This topology utilizes the "open-Delta" configuration to independently control the current in each of the two remaining healthy phases. This new control technique leads to the alleviation of any torque pulsations resulting from the consequences of the asymmetrical conditions associated with this class of faults.

• 대한기계학회논문집A
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• 제32권3호
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• pp.232-239
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• 2008

The position sensors used in a magnetic bearing system are desirable to provide some degree of fault-tolerance as the rotor position is necessary for the feedback control to overcome the open-loop instability. In this paper, we propose an inductive position sensor that can cope with a partial fault in the sensor. The sensor has multiple poles which can be combined to sense the in-plane motion of the rotor. When a high-frequency voltage signal drives each pole of the sensor, the resulting current in the sensor coil contains information regarding the rotor position. The signal processing circuit of the sensor extracts this position information. In this paper, we used the magnetic circuit model of the sensor that shows the analytical relationship between the sensor output and the rotor motion. The multi-polar structure of the sensor makes it possible to introduce redundancy which can be exploited for fault-tolerant operation. The proposed sensor is applied to a magnetically levitated turbo-molecular vacuum pump. Experimental results validate the fault-tolerance algorithm.

• 정보처리학회논문지A
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• 제16A권4호
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• pp.235-244
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• 2009

대공방어용 임무지향 컴퓨터는 장시간의 대공방어 임무를 성공적으로 완수하기 위하여 고장감내 기능이 필수적으로 요구되며, 고장감내 기법으로는 지상 장비인 임무지향 컴퓨터에 적합한 저비용의 기법이 요구된다. 현재 기본형의 임무지향 컴퓨터에는 저비용의 ASR 고장 감내 기법이 적용되어 있으나, ASR 기법은 TMR 기법을 적용한 컴퓨터에 비해 낮은 임무 신뢰도를 제공한다. 그러므로 본 논문에서는 TMR 기법을 적용한 컴퓨터 보다 적은 수량의 프로세서 보드를 사용하여 우수한 신뢰도를 제공하는 확장형 ASR(EASR) 고장 감내 기법을 제안하였으며, 제안된 EASR 기법 을 적용한 임무지향 컴퓨터의 고장 감내 성능을 입증하였다. EASR 기법의 임무지향 컴퓨터는 고장 감내 성능과 저비용성 측면에서 대공방어 시스템의 컴퓨터에 적합하였다.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1241-1248
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• 2006

In high reliability systems for industrial network such as railway signal system, fieldbus protocols have been known to satisfy the real-time and fault tolerant requirements. But, the application of fieldbus has been limited due to the high cost of hardware and software, and the difficulty in interfacing with multi-vendor products. Therefore, as an alternative to fieldbus, the computer network technology, especially Ethernet(IEEE 802.3), is being adapted to the industrial network. In this paper, we propose a switched Ethernet based railway signal system because of its very promising prospect for industrial application due to the elimination of uncertainties in the network operation. In addition, we propose the redundancy architecture for the reliability of network components. More specifically, this paper presents an analytical performance evaluation of switched Ethernet for railway signal system, and shows experimental evaluation of redundancy architecture.

• Journal of Power Electronics
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• 제9권6호
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• pp.949-959
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• 2009

This paper presents a systematic investigation of the fault-mode behaviors of matrix converter systems. Knowledge about converter behaviors after fault occurrence is important from the standpoint of reliable system design, protection and fault-tolerant control. Converter behaviors have been, in detail, examined with both qualitative and quantitative approaches for key fault types, such as switch open-circuited faults and switch short-circuited faults. Investigating the fault-mode behaviors of matrix converters reveals that converter operation with switch short-circuited faults leads to overvoltage stresses as well as overcurrent stresses on other healthy switching components. On the other hand, switch open-circuited faults only result in overvoltage to other switching components. This study can be used to predict fault-mode converter behaviors and determine additional stresses on remaining power circuit components under fault-mode operations.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.371-374
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• 2004

Induction motors are a critical component of many industrial processes and are frequently integrated in commercially available equipment. Safety, reliability, efficiency, and performance are some of the major concerns of induction motor applications. Preventive maintenance of induction motors has been a topic great interest to industry because of their wide range application of industry. Since the use of mechanical sensors, such as vibration probes, strain gauges, and accelerometers is often impractical, the motor current signature analysis (MACA) techniques have gained murk popularity as diagnostic tool. Fault tolerant control (FTC) strives to make the system stable and retain acceptable performance under the system faults. All present FTC method can be classified into two groups. The first group is based on fault detection and diagnostics (FDD). The second group is independent of FDD and includes methods such as integrity control, reliable stabilization and simultaneous stabilization. This paper presents the fundamental FDD-based FTC methods, which are capable of on-line detection and diagnose of the induction motors. Therefore, our group has developed the embedded distributed fault tolerant and fault diagnosis system for industrial motor. This paper presents its architecture. These mechanisms are based on two 32-bit DSPs and each TMS320F2407 DSP module is checking stator current, voltage, temperatures, vibration and speed of the motor. The DSPs share information from each sensor or DSP through DPRAM with hardware implemented semaphore. And it communicates the motor status through field bus (CAN, RS485). From the designed system, we get primitive sensors data for the case of normal condition and two abnormal conditions of 3 phase induction motor control system is implemented. This paper is the first step to drive multi-motors with serial communication which can satisfy the real time operation using CAN protocol.

• 전력전자학회논문지
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• 제12권1호
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• pp.74-80
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• 2007

본 논문에서는 2상 여자 방식으로 구동하는 전압형 인버터 스위치에 발생한 개방 고장을 검출하는 기법을 제안한다. 제안된 기법은 인버터 각 상의 하단 스위치에 전압 센서를 사용하여 동작 모드에 따라 개방 고장을 판별한다. 이는 구현이 간단하고 빠른 고장 판별이 가능하며 부하의 영향을 거의 받지 않기 때문에, 시스템의 신뢰성을 향상시킨다. 또한 4-스위치 인버터 구동을 적용한 재구성을 통하여 고장 발생시에도 고장의 영향을 최소화 하면서 연속적인 운전을 가능하게 했다. 제안된 고장 검출 알고리즘의 타당성은 실험결과로 검증한다.