• Journal of Korean Institute of Industrial Engineers
• /
• v.35 no.1
• /
• pp.87-91
• /
• 2009

In the server disconnection problem, a network with m servers and their users is given and an attacker is to destroy a set of edges to maximize his net gain defined as the total disconnected utilities of the users minus the total edge-destruction cost. The problem is known to be NP-hard. In this paper, we study the server disconnection problem restricted to a ring network. We present an efficient combinatorial algorithm that generates an optimal solution in polynomial time.

• Management Science and Financial Engineering
• /
• v.11 no.1
• /
• pp.49-61
• /
• 2005

We consider the graph disconnection problem, which is to find a set of edges such that the total cost of destroying the edges is no more than a given budget and the weight of nodes disconnected from a designated source by destroying the edges is maximized. The problem is known to be NP-hard. We present an integer programming formulation for the problem and develop an algorithm that includes a preprocessing procedure for reducing the problem size, a heuristic for providing a lower bound, and a cutting plane algorithm for obtaining an upper bound. Computational results for evaluating the performance of the proposed algorithm are also presented.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.29 no.1
• /
• pp.113-125
• /
• 2004

The network disconnection problem ms to find a set of edges such that the total cost of removing the edges is no more than a given budget and the weight of nodes disconnected from a designated source by removing edges is maximized. Martel et at. have shown that the problem with unit capacity and unit demand Is NP-hard and Myung and kim present an integer programming formulation and develop an algorithm that Includes a preprocessing procedure and lower and upper bounding strateagies. in this paper, we present new findings on the properties of the optimal solution and an alternative integer programming formulation, based on which new lower and upper bounding strategies are developed. Computational results for evaluating the performance of the proposed algorithm are also presented.

• Journal of the Korea Convergence Society
• /
• v.8 no.8
• /
• pp.77-82
• /
• 2017

In the splay manufacturing process, conveyor systems are widely used for conveying panels. In this conveyor, a large number of grounding lines are used in order to prevent a product failure due to static electricity. In many cases, the grounding line is disconnected due to the rotation of the transporting roller or curling, leading to product failure. In order to solve such a problem, there is a growing need for a system capable of detecting disconnection of a ground wire in real time. Therefore, in this paper, we propose a disconnection monitoring system of ESD (Electro-Static Discharge) ground wire caused by friction between the conveyor drive part and the panel. The proposed system is a monitoring system that can detect disconnection and disconnection of ground wire using ATmega 2560 and Wheatstone Bridge circuit. It can detect disconnection of ground wire immediately and can take measures to reduce the defect rate due to static electricity. The system proposed in this paper is expected to be applicable to the production and test equipments of all industries where the ground wire is used.

• Journal of Digital Contents Society
• /
• v.9 no.4
• /
• pp.533-541
• /
• 2008

In distributed mobile systems, the congestion control and disconnection problems are current major issues. This paper proposes a grouping-based fuzzy reference streaming method to improve the performance of systems supporting distributed mobile transactions. The proposed method resolves transaction requests issued by mobile clients using the GS interface. In the paper disconnection problems are resolved efficiently using transaction read and update for improved streaming service. Experimental results show that the proposed method outperforms the other existing methods significantly.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.28 no.4
• /
• pp.131-143
• /
• 2003

In this paper, we present a survey about the various graph partition problems including the clustering problem, the k-cut problem, the multiterminal cut problem, the multicut problem, the sparsest cut problem, the network attack problem, the network disconnection problem. We compare those problems focusing on the problem characteristics such as the objective function and the conditions that the partitioned clusters should satisfy. We also introduce the mathematical programming formulations, and the solution approaches developed for the problems.

• Journal of Families and Better Life
• /
• v.29 no.4
• /
• pp.175-186
• /
• 2011

The purpose of this study was to explore the differences in interactive peer play according to the type of problem behavior. The subjects were 112(67 boys, 45 girls) S-year-old children at 25 daycare centers in Seoul, Gyeonggi, and Gyeongsang areas. Instruments included the Preschool Behavior Questionnaire(PBQ; Behar & Stringfield, 1974) and the Penn Interactive Peer Play Scale(PIPPS) in both the teacher version(Choi & Shin, 2008) and the parent version(Fantuzzo, Mendez, & Tighe, 1998). The data were analyzed with descriptive statistics, cluster analysis, t-test, and one-way ANOVA using the SPSS 18.0 software program. The results showed that the clusters of problem behaviors on the PBQ could be grouped into four categories; 'hostility-aggressiveness', 'hyperactivity- distractibility', 'anxiety-fear', and 'combined'. In addition, group differences among the problem behaviors were significantly found in 'play disruption' and 'play disconnection' but not in 'play interaction' of the PIPPS on teachers' and parents' ratings. Specifically, group differences were not found in the parental reports, while significant group differences were noted in the 'play disconnection on PIPPS component of the teachers' reports.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.10
• /
• pp.1448-1453
• /
• 2015

In this paper, we propose an alternative method of communication to improve the reliability of in-vehicle networks by jointly using wireless communication networks. Wired Communication networks have been used in vehicles for the monitoring and the control of vehicle motion, however, the disconnection of wires or hardware fault of networks may cause a critical problem in vehicles. If the network manager detects a disconnection or faults in wired in-vehicle network like the Controller Area Network(CAN), it can redirect the communication path from the wired to the wireless communication like the Zigbee network. To show the validity and the effectiveness of the proposed in-vehicle network architecture, we implement the Electronic Stability Control(ESC) system as ECU-In-the-Loop Simulation(EILS) and verify that the control performance can be kept well even if some hardware faults like disconnection of wires occur.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.05a
• /
• pp.1034-1035
• /
• 2006

본 논문에서는 기존의 노드 단절 문제와 관련이 있는 k-서버 단절 문제를 정의하고, 계산 복잡도 및 근사해성에 대해 규명하였다. k-서버 단절 문제는 비근사성(inapproximaton)을 갖으며, 우리는 k가 고정됐을 때 0.5-근사해법을 갖는다는 것을 보였다.

• Journal of Korea Multimedia Society
• /
• v.20 no.9
• /
• pp.1527-1540
• /
• 2017

Recently, due to the rapid development of the internet, the production and demand of high capacity contents are rapidly increasing. In order to accommodate the changing trend of internet usage, researches on CCN, the future internet architecture, are actively being conducted. Mobility support is an important challenge in CCN real-time services, given that today's internet environment is changing to mobile and real-time services are increasing. In CCN real-time services, the mobility problem can be largely divided into consumer mobility, provider mobility, and intermediate-node mobility. Among them, when the intermediate-node moves in the CCN real-time services, the service disconnection occurs and the QoS degradation is caused. In this paper. we propose Intermediate-Node Mobility Support(INMS) to support the intermediate-node mobility in CCN real-time services. Experimental results show that the proposed scheme shows better performance than CCN in terms of service disconnection time and packet loss.