• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2733-2735
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• 2002

본 논문에서는 원자력 발전소용 이더넷 기반 링형 실시간 제어 통신망인 ERCNet(Ethernet-based Real-Time Control Network)에서 고신뢰성을 유지하기 위한 결함 허용 방법들을 제시한다. 임의의 노드의 프로그램 동작에 이상(fault)이 발생하였을 경우, 와치독(Watchdog) 타이머로 탐지하여 링을 자동 복구하고, 그 노드가 다시 회복될 경우의 노드 추가 메커니즘을 제안한다. 이 메커니즘은 한 노드가 전체 네트워크에서 제외되거나 추가될지라도 네트워크가 운용성(operability)을 유지할 수 있도록 한다. 두 번째로, 한 채널 또는 양 채널 에러 발생시 이 에러를 대처하기 위한 채널 이중화 방식과 시스템 이중화 방식에 대해 제안한다. 마지막으로 통신망의 임의의 위치에서 이상이 발생했을 경우 그 발생 위치를 파악할 수 있는 메커니즘을 제안한다.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.6
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• pp.689-694
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• 2014

An SPLC (Safety Programmable Logic Controller) must be designed to meet the highest safety standards, IEEE 1E, and should guarantee a level of fault-tolerance and high-reliability that ensures complete error-free operation. In order to satisfy these criteria, I/O modules, communication modules, processor modules and bus modules of the SPLC have been configured in triple or dual modular redundancy. The redundant modules receive the same data to determine the final data by the voting logic. Currently, the processor of each rx module performs the voting by deciding on the final data. It is the intent of this paper to prove the improvement on the current system, and develop a voting system for multiple data on a system bus level. The new system bus protocol is implemented based on a TCN-MVB that is a deterministic network consisting of a master-slave structure. The test result shows that the suggested system is better than the present system in view of its high utilization and improved performance of data exchange and voting.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.315-321
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• 2014

This paper presents an integrated chassis control system with fail safety using optimum yaw moment distribution for a vehicle with steer-by-wire and brake-by-wire devices. The proposed system has two-level structure: upper- and lower-level controllers. In the upper-level controller, the control yaw moment is computed with sliding mode control theory. In the lower-level controller, the control yaw moment is distributed into the tire forces of active front steering(AFS) and electronic stability control(ESC) with the weighted pseudo-inverse based control allocation(WPCA) method. By setting the variable weights in WPCA, it is possible to take the sensor/actuator failure into account. In this framework, it is necessary to optimize the variables weights in order to enhance the yaw moment distribution. For this purpose, simulation-based tuning is proposed. To show the effectiveness of the proposed method, simulations are conducted on a vehicle simulation package, CarSim.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.389-396
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• 2005

In this paper, we design AVTMRWFSV(All Voting Triple Modular Redundancy With Fail-Safe Voter) System with a fail-safe output voter architecture and analyze RAMS(Reliability, Availability, Maintainability, Safety) as system failure rate. This system is compared with AVTMR system for RAMS(Reliability, Availability, Maintainability, Safety) with Markov modeling, and we can see that the system safety of AVTMRWFSV is more profitable than that of AVTMR. The dependability of AVTMRWFSV system is higher than that of AVTMR. Especially, safety is very profitable. So, this kind of system can be applied to embedded communication system and life critical systems - railway, airplane, ship, nuclear control system and so on.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1333-1341
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• 2010

The goal of this research is to enhance the maintenance and monitoring system of ship environment using sensor network. It is important to know the location information of sensor nodes to control the sensors and to obtain the sensor data from sensor network inside the ship. In this paper, we address the grouping and routing mechanism according to the relative distance of sensor nodes, based on LEACH and PEGASIS. We also consider the fault tolerant mechanism using the location information of sensor nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1162-1169
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• 2012

One of the important operational requirements for mission critical Ethernet networked system is having the fault tolerant capability. Such capability can be obtained by equipping multiport Network Interface Card (NIC) in each node in the system. Conventional NIC uses two or more Media Access Controls (MACs) and a co-processor for the MAC switching whenever an active port fails. Since firmware is needed for the co-processor, longer fail-over switching and degraded throughput can be generally expected. Furthermore the system upgrading requiring the firmware revision in each tactical node demands high cost. In this paper we propose a novel single MAC based NIC that does not use a co-processor, but just use general discrete building blocks such as MAC chip and switching chip, which results in better performances than conventional method. Experimental results validate our scheme.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.1-10
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• 1999

A mobile computing environment is one that support user's mobility through the wireless communication technology. Users access the database and get results what they want by running mobile transactions. To run the mobile transaction correctly and to maintain the consistency I database, we need a concurrency control method to schedule transactions, a caching method to manage the cache, and a recovery method to construct a fault tolerant system. A mobile computing system is based on the existing distributed system, but we can't use recovery methods of the existing distributed system directly because of the user's mobility and the features of wireless media. So this paper presents a recovery mechanism to construct a fault tolerant mobile computing systems. Especially. we develop and analyze a recovery algorithm for server failure among types of failure which can arise in mobile computing environments.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.245-247
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• 1992

We utilize as a processor TMS320C25 (Texas Instrument) in making a driver for a 4 pole PM synchronous servo motor. TMS320C25 has a 32bit ALU and a 16 bit hardware multiplier, and the maximum instruction execution rate is 10MIPS at 40MHz. We adopted a space vector modulation PWM method. An interesting point of this work is that PWM wave is generated by utilizing timer interrupts. Hence, in the rest of time the processor can take care of the other routine such as Park's coordinate transformation and the computation required in the feedback loops. Thus, it mates the hardware circuit very simple. Due to the decrease in the number of components, the motor drive system becomes more fault-tolerant and cost-optimized. Also, more flexibility is gained in changing the control parameters.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.264-269
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• 2002

A Dual-Path Ethernet Module(DPEM) is developed to improve Local Area Network (LAN)'s performance, High Availability(H/A) and security. Since a DPEM simply locates at the front end of any network device as a transparent add-on, it does not require sophisticated server reconfiguration. Our evaluation results show that the developed scheme is more efficient than conventional LAN structures in various aspects.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.212-213
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• 2019

High power and energy applications of battery require a large number of batteries to be connected in series, parallel or mixed configurations. The reliability or these batteries is improved by making them tolerant to faults i.e. by bypassing the fault cells and adding new cells to compensate the voltage and current requirement. The addition or removal or cells may cause the current stress on other healthy cells. The estimation and control or this current stress is one or the technique proposed by other researchers. This study intends to identify a suitable scalable configuration which can either avoid or reduce the efforts on the estimation and control of stress current. In addition, this paper will explore the issues associated with hot-swap.