• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.11a
• /
• pp.467-474
• /
• 1999

In this paper, Fault tolerant digital governor, using duplex I/O module and triplex CPU module and also 2 out of 3 voting algorithm and adding self diagnostic ability, is designed to realize ceaseless controlling and to improve the reliability of control system. The processor module of the system(SIDG-3000) is developed based on MC68EC040 32 Bit of Motorola, which guaranteed high quality of the module ,and SRAM for data also SRAM for command are separated. The process module also includes inter process communication function and power back up function (SRAM for back-up). System reliability is estimated by using the model of Markov process. The reliability of triplex system in mission time can be improved about 1.8 times in reliability 86%. 2.8 times in 95 %, 6 times in 99 % compared with a single control system. Designed digital governor system is applied after modelling of the steam turbine generator system of Buk-Cheju Thermal Power Plant. Simulation is carried out to prove the effectiveness of the designed digital governor system

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.3
• /
• pp.397-404
• /
• 2011

In this research, wish to suggest method to embody system that can accommodate defect of PLC and find actual propriety. Defect permission control system minimizes production damage because enables repair and checking without discontinuance and improve believability about whole system. Propose duplexing of system to embody this fault tolerant system. Therefore, composed control system that can permit defect or breakdown duplexings of various module proposing this system, and confirms to simulation and actuality kiln of defect permission control system through an application experiment, and compares for mean time between defect by estimate and defect special quality and system configuration of failure(failure) to improve believability of PLC control system together. In proposed system expression method and system mode and relation with operation mode, error discovery mode and switching tube of duplexing mode, and PLC's central processing unit of node study algorithm about master-standby conversion driving and continuous operation of 2 channels method that have 2 that is not one and deduced continuous operation method and result about defect permission in this algorithm and applies this result to actuality kiln control system and confirms continuous operation about PLC defect permission.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.12C
• /
• pp.1123-1130
• /
• 2009

The advances in networking technology and importance of multimedia communication require real time transaction. In many applications, high reliable real-time communications are required more frequently. In this paper, we propose a reliable communication in cube-based multi -computer using the safety vector. Each node in a cube-based n dimensional multi-computer is associated with a safety vector of n bits, which is an approximated measure of the number and distribution of faults in the neighborhood. We propose an algorithm that can establish detour paths using the safety vector. The established detour paths are disjoint with the primary real-time channel. Therefore, our algorithm is more efficient than earlier proposed algorithms.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.05a
• /
• pp.23-26
• /
• 2004

Recently, most of countries in the world are investing huge amount of capital for the infrastructure of logistics and trying to gain dominating position in logistics. To play the role of important hub in logistics, an efficient, flexible, and fault-tolerant transportation process should be developed. Minimization of transportation cost and timely deliveries in the unpredictable environment are a few of the important issues in logistics. This study suggests a way of transporting goods to destinations at the minimal cost and with the minimal delay by optimally allocating transporting resources. Various attributes in transportation such as due date, priority etc. are also considered. Appropriate transporting resources for each work item is selected by calculating the weighted sum of the cost factor and the delay factor assuming that initial sequences of work items are given. A policy to reallocate transporting resources is also suggested when work items or transporting resources are added or deleted because of accidents or disturbances. This policy provides adaptability to the allocation methodology which enables the system to cope with changing environment by controlling various attributes in transportation. Genetic algorithm is used for this approach.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.5
• /
• pp.913-919
• /
• 2011

In this paper, we present a new efficient event detection algorithm for sensor networks with faults. We focus on multi-attributed events, which are sets of data points that correspond to interesting or unusual patterns in the underlying phenomenon that the network monitors. Conventional algorithms cannot detect some events because they treat only their own sensor readings which can be affected easily by environmental or physical problem. Our approach exploits spatio-temporal correlation of sensor readings. Sensor nodes exchange a fault-tolerant code encoded their own readings with neighbors, organize virtual sensor readings which have spatio-temporal correlation, and determine a result for multi-attributed events from them. In the result, our proposed algorithm provides improvement of detecting multi-attributed events and reduces the number of false-negatives due to negative environmental effects.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.2
• /
• pp.242-250
• /
• 1996

Communications on hypercube nodes are done by explicit message routing. So efficient message routing is very important for the performance of hypercube multicomputers. However, hypercube nodes can be faulty due to hardware and/o r software problems, which is called an injured hypercube. A reliable hypercube system should tolerate the problems. One of the methods to enhance reliability on injured hypercube is to use fault-tolerant message routing algorithms. In this paper, we propose a message routing algorithm with possible shortest distance using disjoint paths. To analyze the performance, the algorithm is simulated and evaluated.

• Journal of Information Processing Systems
• /
• v.10 no.1
• /
• pp.36-54
• /
• 2014

Resource sharing is a major advantage of distributed computing. However, a distributed computing system may have some physical or virtual resource that may be accessible by a single process at a time. The mutual exclusion issue is to ensure that no more than one process at a time is allowed to access some shared resource. The article proposes a token-based mutual exclusion algorithm for the clustered mobile ad hoc networks (MANETs). The mechanism that is adapted to handle token passing at the inter-cluster level is different from that at the intra-cluster level. It makes our algorithm message efficient and thus suitable for MANETs. In the interest of efficiency, we implemented a centralized token passing scheme at the intra-cluster level. The centralized schemes are inherently failure prone. Thus, we have presented an intra-cluster token passing scheme that is able to tolerate a failure. In order to enhance reliability, we applied a distributed token circulation scheme at the inter-cluster level. More importantly, the message complexity of the proposed algorithm is independent of N, which is the total number of nodes in the system. Also, under a heavy load, it turns out to be inversely proportional to n, which is the (average) number of nodes per each cluster. We substantiated our claim with the correctness proof, complexity analysis, and simulation results. In the end, we present a simple approach to make our protocol fault tolerant.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.1
• /
• pp.128-136
• /
• 2008

In this paper, we propose a new cache structure for effective error correction of soft error. We added check bit and SEEB(soft error evaluation block) to evaluate the status of cache line. The SEEB stores result of parity check into the two-bit shit register and set the check bit to '1' when parity check fails twice in the same cache line. In this case the line where parity check fails twice is treated as a vulnerable to soft error. When the data is filled into the cache, the new replacement algorithm is suggested that it can only use the valid block determined by SEEB. This structure prohibits the vulnerable line from being used and contributes to efficient use of cache by the reuse of line where parity check fails only once can be reused. We tried to minimize the side effect of the proposed cache and the experimental results, using SPEC2000 benchmark, showed 3% degradation in hit rate, 15% timing overhead because of parity logic and 2.7% area overhead. But it can be considered as trivial for SEEB because almost tolerant design inevitably adopt this parity method even if there are some overhead. And if only parity logic is used then it can have $5%{\sim}10%$ advantage than ECC logic. By using this proposed cache, the system will be protected from the threat of soft error in cache and the hit rate can be maintained to the level without soft error in the cache.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.415-416
• /
• 2011

본 논문은 계통연계형 전력변환 장치의 폐루프 제어에 이용되는 전류센서의 고장진단 및 허용운전 기법을 제안한다. 전류 센서에 고장이 발생하면, 정확한 출력전력제어가 불가능해져 품질이 저하될 뿐만 아니라 이에 대한 허용운전이 이루어지지 않으면 전체시스템의 운전을 중지해야 한다. 따라서 실시간 고장진단 및 허용운전 기법이 필요하다. 제안한 기법은 측정된 값과 추정 값의 비교를 통해 고장진단을 하고, 고장발생시 정상 센서에서 측정된 전류 값을 이용하여 허용운전을 한다. 10kW급 3병렬 전력 변환 시스템을 모의한 시뮬레이션을 통해 제안한 기법의 성능을 검증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.10
• /
• pp.5197-5218
• /
• 2019

Large-scale retrieval algorithm is problem for visual analyses applications, along its research track. In this paper, we propose a high-efficiency region division-based image retrieve approaches, which fuse low-level local color histogram feature and texture feature. A novel image region division is proposed to roughly mimic the location distribution of image color and deal with the color histogram failing to describe spatial information. Furthermore, for optimizing our region division retrieval method, an image descriptor combining local color histogram and Gabor texture features with reduced feature dimensions are developed. Moreover, we propose an extended Canberra distance method for images similarity measure to increase the fault-tolerant ability of the whole large-scale image retrieval. Extensive experimental results on several benchmark image retrieval databases validate the superiority of the proposed approaches over many recently proposed color-histogram-based and texture-feature-based algorithms.