• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1063-1079
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• 2010

Vehicle ad hoc networks (VANET) are one of the most important technologies to provide various ITS services. While VANET requires rapid and reliable transmission, packet transmission in VANET is unstable because of high mobility. Many routing protocols have been proposed and assessed to improve the efficiency of VANET. However, topology-based routing protocols generate heavy overhead and long delay, and position-based routing protocols have frequent packet loss due to inaccurate node position. In this paper, we propose a position-based routing repair algorithm to improve the efficiency of VANET. This algorithm is proposed based on the premise that AODV (-PGB) can be used effectively in VANET, if the discovery, maintenance and repair mechanism of AODV is optimized for the features of VANET. The main focus of this algorithm is that the relay node can determine whether its alternative node exits and judge whether the routing path is disconnected. If the relay node is about to swerve from the routing path in a multi-hop network, the node recognizes the possibility of path loss based on a defined critical domain. The node then transmits a handover packet to the next hop node, alternative nodes and previous node. The next node repairs the alternative path before path loss occurs to maintain connectivity and provide seamless service. We simulated protocols using both the ideal traffic model and the realistic traffic model to assess the proposed algorithm. The result shows that the protocols that include the proposed algorithm have fewer path losses, lower overhead, shorter delay and higher data throughput compared with other protocols in VANET.

• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.89-98
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• 1994

In this paper, a criteria for selecting an appropriate load redistribution algorithm is devised so that a fault-tolerance distributed system can operte at its optimal efficience. To present the guideline for selecting redistributing algorithms, simulation models of fault-tolerant system including redistribution algorithms are developed using SLAM II. The job arrival rate, service rate, failure and repair rate of nodes, and communication delay time due to load migration are used as parameters of simulation. The result of simulation shows that the job arrival rate and the failure rate of nodes are not deciding factors in affecting the relative efficiency of algorithms. Algorithm B shows relatively a consistent performance under various environments, although its performance is between those of other algorithms. If the communication delay time is longer than average job processing time, the performance of algorithm B is better than others. If the repair rate is relatively small or communication delay time is longer than service time, algorithm A leads to good performance. But in opposite environments, algorithm C is superior to other algorithms.

• Industrial Engineering and Management Systems
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• v.8 no.3
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• pp.194-200
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• 2009

This study provides a heuristic algorithm to solve the locating problem of repair service centers (RSCs). To enhance the customer service level with more satisfaction and quicker responsiveness, the locating problem of RSCs has become one of the important issues in reverse supply chain management. This problem is formulated as a zero-one mixed integer programming in which an exiting distributor will be considered to be an un-capacitated repair service center for the objective of cost-minimizing. Since logistical costs are highly interrelated with the multinational location of distributors and RSCs, the fixed cost for setting a repair service center, variable cost, transportation cost, and exchange rates are considered in this study. Recognizing the selection of un-capacitated RSCs' locations is a combinatorial optimization problem and is a zero-one mixed integer programming with NP-hard complexity, we provide a heuristic algorithm named as incremental cost matrix procedure (ICMP) to simplify the solving procedure. By using the concise and structural cost matrix, ICMP can efficiently screen the potential location with cost advantage and effectively decide which distributor should be a RSC. Results obtained from the numerical experiments conducted in small scale problem have shown the fact that ICMP is an effective and efficient heuristic algorithm for solving the RSCs locating problem. In the future, using the extended ICMP to solve problems with larger industrial scale or problems with congestion effects caused by the variation of customer demand and the restriction of the RSC capacity is worth a further investigation.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.59-66
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• 2009

This has been possible by integration techniques such as very large scale integration (VLSI) and wafer scale integration (WSI). Redundancy has been extensively used for manufacturing memory chips and to provide repair of these devices in the presence of faulty cells. If there are too many defects, the momory has to be rejected. But if there are a few defects, it will be more efficient and cost reducing for the company to use it by repairing. Therefore, laser-repair process is nedded for such a reason and redundancy analysis is needed to establish correct target of laser-repair process. The proposed CRA (Correlation Repair Algorithm) simulation, beyond the idea of the conventional redundancy analysis algorithm, aims at reducing the time spent in the process and strengthening cost competitiveness by performing redundancy analysis after simulating each case of defect.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.151-155
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• 2002

Memory의 공정기간은 2∼3개월 정도, 공정은 수백가지에 이를 정도로 많기에 defect은 존재할 수밖에 없다. 많은 defect이 있다면 어쩔 수 없겠지만 적은 defect이 발생한 경우에는 해당 die를 reject시키는 것보다는 repair해서 사용하는 것이 memory생산 업체 입장에서는 보다 효율적이고 원가 절감 차원에서 필수적이다. 이와 같은 이유로 laser repair라는 공정이 필요하고 laser repair공정의 정확한 target을 설정하기 위해 redundancy analysis가 필요하게 되었다. 지금까지 redundancy analysis는 장비 개발 업체에서 제공하는 경우가 대부분 이었고 각 장비 제조 업체별로 redundancy analysis algorithm을 개발하여 제공하여왔기에 동일한 defect 유형에 분석하는 redundancy analysis time이 각 장비 업체 별로 다른 경우가 대부분이었다. 이에 본 연구에서는 기존의 redundancy analysis algorithm의 개념에서 벗어나 defect 유형별로 simulation한 후 redundancy analysis를 진행함으로써 redundancy analysis에 소요되는 시간을 절약함으로써 원가 경쟁력 강화를 하고 correlation 개념을 업무에 적용하는데 목적이 있다

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.521-523
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• 1997

In this paper, We carried out investigation of monitoring algorithm development for electric car inspection and repair. For transmitting a data, reliable RS-422 is adopted. The LabWindows/CVI development tool of National Instruments Co. is used for the formation of monitoring screen. The experimental set-up is composed of a PC to PC system. It is applicable to electric car imspection and repair.

• ETRI Journal
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• v.32 no.4
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• pp.638-641
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• 2010

With the growth of memory capacity and density, memory testing and repair with the goal of yield improvement have become more important. Therefore, the development of high efficiency redundancy analysis algorithms is essential to improve yield rate. In this letter, we propose an improved built-in redundancy analysis (BIRA) algorithm with a minimized binary search tree made by simple calculations. The tree is constructed until finding a solution from the most probable branch. This greatly reduces the search spaces for a solution. The proposed BIRA algorithm results in 100% repair efficiency and fast redundancy analysis.

• ETRI Journal
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• v.34 no.3
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• pp.478-481
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• 2012

Testing memory and repairing faults have become increasingly important for improving yield. Redundancy analysis (RA) algorithms have been developed to repair memory faults. However, many RA algorithms have low analysis speeds and occupy memory space within automatic test equipment. A fast RA algorithm using simple calculations is proposed in this letter to minimize both the test and repair time. This analysis uses the grouped addresses in the faulty bitmap. Since the fault groups are independent of each other, the time needed to find solutions can be greatly reduced using these fault groups. Also, the proposed algorithm does not need to store searching trees, thereby minimizing the required memory space. Our experiments show that the proposed RA algorithm is very efficient in terms of speed and memory requirements.

• The Transactions of the Korea Information Processing Society
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• v.4 no.6
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• pp.1615-1624
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• 1997

In this paper, we propose and analyze various repair methods for a disk subsystem using mirroring. We also study the effects of the repair process that is invoked on disk faults on the mean response time of user disk requests. Finally, we analyze the effects of two different access patterns (uniform and non-uniform) on the repair process and performance. According to the results, average response times for non-uniform access pattern compared with uniform access pattern become shorter as the system load increases. Our simulation results show that the proposed repair algorithm with a short delay gives a better performance than the previous algorithms.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.8
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• pp.1-10
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• 1994

In this paper load redistribution algorithm to allow fault-tolerance by redistributing the workload of n failure nodes to the remaining good nodes in distributed systems are investigated. To evaluate the efficiency of the algorithms a simulation model of algorithms is developed using SLAM II simulation language. The job arrival rate service rate failure and repair rate of nodes and communication delay time due to load migraion are used as parameters. The result of the simulation shows that the job arrival rate failure and repair rate of nodes do not affected on the relative efficiency of algorithms. If the communication delay time is greater than average job processing time algorithm B is better. Otherwise algorithm C is superior to the others.