• Journal of KIISE:Computing Practices and Letters
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• v.7 no.2
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• pp.121-131
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• 2001

The failure of network and/or node on which server object is executed is a single point of system failure in the CORBA application. One of the possible ways to overcome such problem is to replicate server objects to several independent nodes. The replicated objects executing same tasks are called object group. In order to provide fault tolerance of server object, this paper proposes and implements new CORBA model that supports the object group based on active replication. The proposed model not only provides interoperability with existing CORBA application but also minimizes additional application interface required to support object group because it uses nop to exchange messages between client and server. And this paper extends IDL structure. Depending to application logic, it makes possible to prevent performance degradation caused by consistency maintenance. At present, this paper supports only active replication. But it can be easily extended to provide warm ancVor cold passive replication without modification of architecture required for active replication.

• The Journal of the Korea Contents Association
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• v.8 no.8
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• pp.37-46
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• 2008

Launch control system controls the sequence for launching missile in weapon systems. This system have to generate the engagement plan, input information and launch the missile in timeliness requirement. Such a system may fail to operate correctly either due to errors in hardware and software or due to violation of timing constraints. We presented fault-tolerant ethernet for embedded real-time system like launch control system. This approach is designed to handle network faults using dual commercial-off-the-shelf(COTS) network devices. To support fault-tolerant ethernet each node is composed dual channel ethernet and designed the communication middleware for network fault detect and recovery. Especially for time-critical system, the middleware is being developed to achieve that no point of network failure shall take down or cause loss of communication to network nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.74-85
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• 2009

We propose an Agent-based Fault Tolerant Object Group model based on the agent technology and FTOG model with replication mechanism for effective object management and fault recovery. We define the five kind of agents - internal processing agent, registration agent, state handling agent, user interface agent, and service agent - that extend the functions of the FTOG model. The roles of the agents in the proposed model are to reduce the remote interactions between distributed objects and provide more effective service execution. To verify the effectiveness of the proposed model, we implemented the Intelligent Home Network Simulator (IHNS) which virtually provides general home networking services. Through the simulations, it is validated that the proposed model decreases the interactions of the object components and supports the effective fault recovery, while providing more stable and reliable services.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.34-42
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• 2006

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires(steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive smoothing voter that can filter out most erroneous values and noise. In addition, several numerical simulation results are given where the predictive smoothing voter outperforms well-known average and median voters.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.89-95
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• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1463-1467
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• 2005

This paper proposes an analytical redundancy technique for fault diagnostics of the sensor in steer-by-wire system. We use incorporating vehicle dynamics modeling into the design of a diagnostic system for steer-by-wire system. The use of a model of vehicle dynamics improves the speed and accuracy of the diagnoses. The proposed fault diagnostics algorithm is based on parity-space methods to generate residuals. To reduce the effects of modeling uncertainty and dynamic transients, the residuals are subject to filtering. We construct diagnostic system consisting residual threshold for detection and isolator with using the directional residual vector.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.10-13
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• 2014

소나 시스템에서 정보처리기는 정보 융합, 시스템 내부 제어 및 외부 시스템 연동 등의 다양한 임무를 수행한다. 정보처리기에 고장이 발생할 경우, 소나 시스템의 운영에 치명적인 영향을 끼치게 되므로 소나 시스템의 생존성 및 신뢰성 향상을 위한 정보처리기의 이중화가 필요하다. 이에 본 논문에서는 소나 시스템을 위한 정보처리기의 이중화 방법을 제시한다. 제안하는 이중화 방법은 하드웨어 중복 및 동기식 이중화 방법을 사용하며 정보처리기 이중화 운용을 위한 master 설정 및 외부 연동 방법 등을 기술하였다.

• Convergence Security Journal
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• v.13 no.3
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• pp.17-23
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• 2013

Clustering is required to configure clustering interdependent structural technology. Clustering handles variable workloads or impede continuity of service to continue operating in the event of a failure. Long as high-availability clustering feature focuses on server operating systems. Active-standby state of two systems when the active server fails, all services are running on the standby server, it takes the service. This function switching or switchover is called failover. Long as high-availability clustering feature focuses on server operating systems. The cluster node that is running on multiple systems and services have to duplicate each other so you can keep track of. In the event of a node failure within a few seconds the second node, the node shall perform the duties broken. Structure for high-availability clustering efficiency should be measured. System performance of infrastructure systems performance, latency, response time, CPU load factor(CPU utilization), CPU processes on the system (system process) channels are represented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.201-209
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• 2009

In power plant operations, sensor values often exhibit erroneous values due to their failures or the intrusions of various noises. However, most of the power plant monitoring and fault diagnosis systems perform their tasks based on the assumptions that the collected sensor values are correct all the times. These assumptions, which are not valid, often lead to serious consequences such as power plant trips. In this paper, we propose a power plant sensor value validation technique that can utilize the relationships existing among the sensor values as the sensor redundancy. The proposed technique is applied to the flow meters installed along boiler feed water systems of a typical tubular type boiler thermal power plant and shows a good potential of future applications.

• The KIPS Transactions:PartD
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• v.9D no.4
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• pp.587-602
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• 2002

Replicated database system was emerged to resolve the problem of reduction of the availability and the reliability due to the communication failures and site errors generated at centralized database system. But if update transactions are many occurred, the update is equally executed for all replicated data. Therefore, there are many problems the same thing a message overhead generated by synchronization and the reduce of concurrency happened because of delaying the transaction. In this paper, I propose a new concurrency control algorithm for enhancing the degree of parallelism of the transaction in fully replicated database designed to improve the availability and the reliability. To improve the system performance in the replicated database should be performed the last operations in the submitted site of transactions and be independently executed update-only transactions composed of write-only transactions in all sites. I propose concurrency control method to maintain the consistency of the replicated database and reflect the result of update-only transactions in all sites. The superiority of the proposed method has been tested from the respondence and withdrawal rate. The results confirm the superiority of the proposed technique over classical correlation based method.