• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권1호
• /
• pp.1-9
• /
• 2000

In this paper, a design method of fault-tolerance is presented for the nuclear digital control systems composed of software and hardware. As a quantitative design method measure of fault-tolerance, we used Reliability, Availability and Safety. To implement the proposed fault-tolerance, a prototype system has been devised for the digital control systems and a quantitative method of 'Markovian Model' is applied. The results provide the appropriate degree of redundancy and diversity, and fail-safe.

• 한국자동차공학회논문집
• /
• 제14권5호
• /
• pp.1-8
• /
• 2006

The Steer-By-Wire(SBW) system replaces complex mechanical linkages of the current steering system with electric motors, sensors, and electronic control units. However, the SBW system should guarantee its safety and reliability before commercialization, and therefore, a reliable and robust fault-tolerant technology has to be implemented. This paper proposes a fault-tolerant control algorithm for the SBW system. Based on careful analysis on propagation effects of sensor faults, a reliable fault-tolerant control strategy has been developed. The fault-tolerant controller consists of a fault detection part that monitors and detects faults in the steering wheel and road wheel sensors, and a reconfiguration part that switches to normal sensor signal based on fault detection information. It has been demonstrated by simulation that the proposed algorithm detects sensor faults accurately and enables reliable steering control under various dynamic fault situations.

• 한국철도학회논문집
• /
• 제10권5호
• /
• pp.527-532
• /
• 2007

본 논문은 철도신호에서 사용되는 이중계제어장치의 전원공급방식에 대하여 상수고장률을 기반으로 하는 평균고장률에 의한 설계와 신뢰도함수에 의한 설계방안을 제안한다. 일반적으로 시스템 운명이전에 신뢰도 요구사항 만족을 위한 시스템의 신뢰도 예측은 RBD모델을 사용하였다. 하지만 이중계제어장치와 같이 여분을 갖는 시스템의 신뢰도를 RBD와 같은 조합모델에 의해 정확한 신뢰도를 모델링하기에 부적합하다. 따라서 본 논문에서는 다중계구조 제어기의 설계과정에서 단순조합모델에 의한 설계방식 선정보다는 결함발생에 대한 여분구조의 모델링을 통한 설계방식 선정이 보다 정확한 신뢰도를 갖는 시스템구축을 가능하게 하며, 운영중에 발생되는 유지보수비용 및 고장으로 인한 손실비용의 효율화를 위해 필요함을 입증한다.

• 한국정보처리학회논문지
• /
• 제1권2호
• /
• pp.172-183
• /
• 1994

멀티 데이타베이스 시스템에서 가장 중요한 사항은 지역 자치성의 보장과 전역적 일관성을 유지하는 것이다. 전역적 일관성은 전역 동시성 제어 알고리즘과 회복 알고 리즘에 의해 유지될 수 있다. 본 논문은 지역 자치성을 보장하면서 전역적 직렬성을 만족하는 전역 동시성 제어 알고리즘과 지역 자치성을 보장하면서 각종 고장으로부터 멀티 데이타베이스를 회복할 수 있는 전역 회복 알고리즘을 제안한다. 제안된 전역 동시성 제어 알고리즘은 상향식 방법으로 3단계 트랜잭션 처리 모델에 기반을 두고, 지역 트랜잭션들로 인하여 부트랜잭션들 사이에 간접 충돌이 발생할 때 서버에서 가상 연산을 사용하여 지역 데이타베이스 시스템에서 수행되는 부트랜잭션들의 수행 순서와 직렬화 순서가 동일하게 유지할 수 있도록 함으로써 간접 충돌 문제를 해결할 수 있다. 저 전역 모듈에서는 충돌 관계가 있는 전역 트랜잭션들에 대해서만 전역적 직렬성을 검사 함으로써 전역적 직렬성 검사를 더욱 효율적으로 할 수 있다.

• 전기학회논문지
• /
• 제56권9호
• /
• pp.1589-1595
• /
• 2007

This paper suggests the advanced reliability assessment tool for railway signaling Hot-Standby sparing system. Existing reliability assessment for Hot-Standby sparing system controller is done by using single module mean failure rate based on approximated Hot standby sparing system function. Although approximated Hot standby sparing system function can be applied to various Hot standby sparing system, however, it is not able to reflect the exact system structure. In this paper, we suggest the advanced reliability function by identifying changeover-related failure factors and common failure mode which is not considered in existing approximated Hot standby sparing system reliability function via developing Hot standby sparing system model for railway signaling and applying FMECA to this model. Also. we compare reliability assessment results for model system to reliability assessment for existing system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
• /
• pp.2687-2689
• /
• 2005

In this paper, a novel algorithm for adaptive majority voting using additional information is described. The novel algorithm increases the reliability of adaptive majority's history. The novel algorithm assists adaptive majority voter to select the result of the most reliable module. The performance of the proposed voter is evaluated through a series of fault injection simulations. The results are compared with those of adaptive majority voter. The empirical results show that the proposed voter has higher safety and availability levels than the adaptive majority voter

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 D
• /
• pp.2376-2378
• /
• 2002

Redundant Programmable Logic Controllers are used in practice with the aim of achieving higher degree of availability or fault tolerance. In the paper a proposed Multiplex-PC is controled for fault tolerance design. In order to select a Different-Vender by a Supervisor computer, a Multiplex-PC is designed by TCP/IP internet protocol[1]. Because TCP/IP internet protocol can not connect to CPU. We use TCP/IP internet protocol to join CPU. We have to use TCP congestion control to select Different-Vender [4]. The reliability of the fault tolerant is measured with MTBF(Mean Time Between Failures)[3].

• 대한전기학회논문지:시스템및제어부문D
• /
• 제50권1호
• /
• pp.8-13
• /
• 2001

LMS algorithm has been used for plant identifier and noise cancellation. This algorithm has been researched for performance enhancement of filtering. The design and development of a reliable system has been becoming a key issue in industry field because the reliability of a system is considered as an important factor to perform the system's function successfully. And the computing with reliability and fault tolerance is a important factor in the case of aviation, system communication, and nuclear plant. This paper presents design of reliable adaptive filter with fault tolerance. Generally, redundancy is used for reliability. In this case it needs computing or circuit for voting mechanism, or fault detection. Therefore it has simple computing, and practicality for application. And in this paper, reliability of adaptive filter is analyzed. The effectiveness of the proposed adaptive filter is demonstrated to the case studies of plant identifier and noise cancellation by using DSP.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 D
• /
• pp.2197-2199
• /
• 2003

Most of distributed PLC system is secured reliability of the system by fully duplicated controller. But it costs too much. In this paper, we proposed fault tolerant control using minimum spare controllers. First, the system is modeled using Galois field. Next, we designed additional spare controllers using the parity code of two dimensions. Finally, the algorithm for producing estimated output in remote I/O when the fault occurs was suggested. This method will be applied to an automatic system in order to increase reliability and improve cost performance.

• 전력전자학회논문지
• /
• 제24권2호
• /
• pp.120-126
• /
• 2019

This study proposes a neutral voltage balance control scheme for stable fault-tolerant operation of an active neutral point clamped (ANPC) inverter using carrier-based pulse width modulation. The proposed scheme maintains the neutral voltage balance by reconfiguring the switching combination and modulating the reference output voltage in order to solve the degradation of the output characteristic in the fault tolerant operation due to the fault of the power semiconductor switch constituting the ANPC inverter. The feasibility of the proposed control scheme is confirmed by HIL experiment using RT-BOX.