• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.138-147
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• 2017

As the functions and structure of the system are complicated and elaborated, various types of structures are emerging to increase reliability in order to cope with a system requiring higher reliability. Among these, standby systems with standby components for each major component are mainly used in aircraft or power plants requiring high reliability. In this study, we consider a standby system with a multi-functional standby component in which one standby component simultaneously performs the functions of several major components. The structure of a parallel system with multifunctional standby components can also be seen in real aircraft hydraulic pump systems and is very efficient in terms of weight, space, and cost as compared to a basic standby system. All components of the system have complete operation, complete failure, only two states, and the system has multiple states depending on the state of the component. At this time, the multi-functional standby component is assumed to be in a non-operating standby state (Cold Standby) when the main component fails. In addition, the failure rate of each part follows the Weibull distribution which can be expressed as increasing type, constant type, and decreasing type according to the shape parameter. If the Weibull distribution is used, it can be applied to various environments in a realistic manner compared to the exponential distribution that can be reflected only when the failure rate is constant. In this paper, Markov chain analysis method is applied to evaluate the reliability of multi-functional multi-state standby system. In order to verify the validity of the reliability, a graph was generated by applying arbitrary shape parameters and scale parameter values through Excel. In order to analyze the effect of multi-functional multi-state standby system using Weibull distribution, we compared the reliability based on the most basic parallel system and the standby system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1717-1722
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• 2016

Availability, one of the important metrics used to assess the performance of network system, is defined as the probability that a system is operational at a given point in time under a given set of environmental conditions. To improve the availability of the network service, the redundancy models and the rejuvenation schemes are the effective schemes to be typically used. In this paper, we analyse the effect of 2N redundancy model and/or rejuvenation scheme on the availability of network service. The 2N redundancy model consists of one active and one standby component and the performance of time-based rejuvenation scheme mainly depends on its rejuvenation period. We design stochastic reward net model for the 2N redundancy model with time-based rejuvenation scheme and analyse the service availability of the model using stochastic Petri net package. We provide some numerical examples of the service availability, which shows that the system with rejuvenation has higher availability than the system without rejuvenation.

• International Journal of Reliability and Applications
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• v.3 no.3
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• pp.147-154
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• 2002

In this paper, we consider the warm standby redundant system(WSRS) which is consisted of an active unit, a standby unit and a switchover device. In addition, the switchover processing is controlled by a control module. The effect of failure of the control module is taken into account to develop our reliability model for the redundant structure. For the performance evaluation of a redundant system with the function of switchover processing which is assumed to cause the increase of the failure rate of the system, some reliability indices, such as availability, average availability, reliability and steady state availability, are considered.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.267-270
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• 2000

In this paper, we consider the simple redundant structures with the function of hardware based active/standby control. The system includes two switch modules. The switch module is connected to a data bus, but only the active switch module has control of the data bus. The standby unit takes over the function of the active unit when the active unit failure or mode command are asserted. And this paper illustrate the high-speed router system and the overall redundant system architecture. The proposed redundant architecture for 80G Router system is verified and implemented with experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1291-1298
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• 2004

In development of monitoring and control systems, one of the most important points is to consider a redundancy so that the system can be operated normally although hardware faults are partly occurred. The purpose of this paper is to introduce a monitoring and control system with a redundancy function for I/O servers and communication networks. I/O servers composed with an active server and a standby server. Each server also has 3 communication ports, 2 ports of them were connected to field units and the other 1 port was connected to the other server. Field units have to be constructed to 2 communication ports connected I/O servers through communication lines. Also, server communication module was implemented for analyzing and handling fault elements. and was submodularized for linking easily with a monitoring and control module. An experiment with 2 servers and 2 field units was constructed to demonstrate its effectiveness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2634-2639
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• 2014

The idea of redundancy is used in order to improve the availability of networks and systems and there are various methods for implementing redundancy. To perform the availability analysis various stochastic models have been used. In this paper, 2N redundancy with one active service unit and one standby service unit is considered. To evaluate the expected availability, we model 2N redundancy using Stochastic Reward Nets. This model can be solved using the SPNP package.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2782-2786
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• 2011

In this paper a protocol design for bus network communication between onboard signalling system and MMI(Man Machine Interface) will be presented and illustrated. Recently, many onboard signailling systems adopt hot standby for safety reasons. Hot standby is a method of redundancy in which the primary and secondary systems run simultaneously. It is convenient to use bus network(bus topology) in a hot standby system for communication between onboard signalling system and MMI. Because bus network is the simplest way to connect multiple clients such as onboard signalling system, MMI and etc. However, there are many problems when two clients want to transmit at the same time on the same bus. A effective protocol is necessary to solve that problems. We will describes protocol design which is useful when onboard signalling systems and MMIs are connected via RS485(Bus Network).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.47-52
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• 2000

Redundant programmable logic controllers are used in practice with the aim of achieving a higher degree of availability or fault tolerance. Redundancy system is fault tolerant programmable logic controller for machine and plant. It is event synchronized master-standby system with a 2 channel(1-out-of-2) structure. A data link connects line the master to the standby controller.Fault tolerant systems should always be used when it is necessary to keep the probability of a total control system failure to a minimum. The objective of using high availability programmable logic controller is a reduction of losses of fault tolerant system are quickly compensated by the avoidance of loss of production.

• Journal of the Korea Convergence Society
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• v.11 no.8
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• pp.47-53
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• 2020

In the case of a failure due to equipment deterioration in the public address system or a worker's mistake during construction, broadcasting becomes impossible. In this situation, we have designed a more advanced management broadcast system that can broadcast. The broadcasting service is operated using main broadcasting device, and local broadcasting device operates separately only in the local area. If the main broadcasting device becomes inoperable, the procedure for transferring the control activates the device with the local broadcasting devices based on data backed up by the main controller. This paper proposes an improved method of the conventional emergency broadcasting device duplication method. The existing method could not use the standby equipment in the normal state, but in the proposed method, the standby equipment can be used as local broadcasting equipment in usually. This method enables stable system operation while minimizing resource waste due to redundant configuration of expensive devices.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1426-1437
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• 2016

In different industrial and mission oriented applications, redundant or standby semiconductor systems can be implemented to improve the reliability of power electronics equipment. The proper structure for implementation can be one of the redundant or standby structures for series or parallel switches. This selection is determined according to the type and failure rate of the fault. In this paper, the reliability and the mean time to failure (MTTF) for each of the series and parallel configurations in two redundant and standby structures of semiconductor switches have been studied based on different failure rates. The Markov model is used for reliability and MTTF equation acquisitions. According to the different values for the reliability of the series and parallel structures during SC and OC faults, a comprehensive comparison between each of the series and parallel structures for different failure rates will be made. According to the type of fault and the structure of the switches, the reliability of the switches in the redundant structure is higher than that in the other structures. Furthermore, the performance of the proposed series and parallel structures of switches during SC and OC faults, results in an improvement in the reliability of the boost dc/dc converter. These studies aid in choosing a configuration to improve the reliability of power electronics equipment depending on the specifications of the implemented devices.