• Journal of KIISE:Computing Practices and Letters
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• v.10 no.5
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• pp.385-393
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• 2004

Cluster systems have been widely used for solving problems in various application domains, and regarded as useful high performance computing resources. As the number of cluster system user is increasing, it is no less important to maintain stable operation than to improve cluster system performance. Although hardware preventive maintenance is important for keeping normal operation, the testing tool which can be used for general cluster systems during maintenance has received little attention. In this Paper, considering hardware Preventive maintenance, we suggest a testing tool for hardware of cluster system. The cluster system testing tool which is named CTS(Cluster system Test Suite) has two check routines; one for memory, and the other for NIC respectively. The CTS is designed to support the common features of general cluster systems and all the Jobs such as setting test conditions to querying the results can be done entirely within an integrated GUI environment. CTS is used as the testing tool for two kinds of cluster systems during maintenance, and the experimental results show that CTS reports useful information for cluster systems management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1801-1810
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• 2016

The OpenDaylight controller has been receiving significant attention as one of the enabling open source framework for SDN, and this paper analyzes the architecture and procedure of OpenDaylight based controller cluster. The OpenDaylight controller cluster uses shard based distributed datastore and Raft algorithm to maintain consistency among controllers inside a cluster. The performance evaluation analyzes the leader re-election time as well as latencies of CRUD and Routed RPC according to cluster size, shard role, and sharding strategy, and we discuss the optimal operation strategy for OpenDaylight controller cluster.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1064-1072
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• 2005

For the efficient operation of sensor networks, it is very important to design sensor networks for sensors to utilize their energies in very effective ways. Cluster-based routing schemes such as LEACH can achieve their energy efficiencies by delivering data between cluster heads and sensor nodes. In those cluster-based schemes, cluster reconfiguration algorithm is one of the most critical issues to achieve longer operation lifetime of sensor networks. In this paper, we propose a new energy efficient cluster reconfiguration algorithm. Proposed method does not require any location or energy information of sensors, and can configure clusters with fair cluster regions such that all the sensors in a sensor network can utilize their energies equally. The performances of the proposed scheme have been compared with LEACH and LEACH-C.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.3
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• pp.122-131
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• 1992

In this paper an approximate solution method for the large-scale Traveling Salesman Problem (TSP) is presented. The method starts with the subdivision of the problem domain into a number of cluster by considering their geometric characteristic. Each cluster has a limited number of nodes so as to get a local solution. They are linked go give the least pathe which covers the whole domain and become TSPs solution with start-and end-node. The approximate local solution in each cluster are obtained based on geometrical properties of the cluster, and combined to give an overall approximate solution for the larte-scale TSP.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.3
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• pp.169-175
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• 2010

Recently, to improve operating efficiency with the higher in-line rate in automated production lines, a lot of cases of grouping machines and material handling system together to form a cluster has shown frequently. This article addresses the job allocation and operation method of automated material handling for cluster-type production systems. First of all, the control problems of the automated material handling systems are classified into the control problem of inter-cluster material handling system and that of intra-cluster material handling system. Then, a distributed agent-based control scheme is proposed for the former, and an operational control procedure for the latter. Simulation experiment shows that the proposed method is efficient in reducing cycle times and improving utilization of material handling vehicles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.10
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• pp.728-737
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• 2019

In this study, the minimized on-board computer (OBC) module for integrated navigation is developed, which provides satellites' relative position information in formation flying and cluster operation situations. The scalability is considered to apply the user-selected wireless communication module and Global Positioning System (GPS) receiver for navigation, while considering to meet the structural design standard of nano-satellites. As a result of the product development and production, the processing speed of integrated navigation and real-time data synchronization is satisfied for cluster operation nano-satellites by using micro controller unit (MCU). From a heat/vacuum, vibration and radiation test, the OBC was confirmed to be operated in space environments. From these results, a mass production system of OBC was made which is a key part of development on satellite formation flying and cluster/constellation missions that the community demands are increasing.

• Journal of information and communication convergence engineering
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• v.22 no.1
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• pp.1-6
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• 2024

Energy efficiency in wireless sensor networks (WSNs) is a critical issue because batteries are used for operation and communication. In terms of scalability, energy efficiency, data integration, and resilience, WSN-cluster-based routing algorithms often outperform routing algorithms without clustering. Low-energy adaptive clustering hierarchy (LEACH) is a cluster-based routing protocol with a high transmission efficiency to the base station. In this paper, we propose an energy consumption model for LEACH and compare it with the existing LEACH, advanced LEACH (ALEACH), and power-efficient gathering in sensor information systems (PEGASIS) algorithms in terms of network lifetime. The energy consumption model comprises energy-sensitive cluster formation and a cluster head selection technique. The setup and steady-state phases of the proposed model are discussed based on the cluster head selection. The simulation results demonstrated that a low-energy-consumption network was introduced, modeled, and validated for LEACH.

• The Journal of Information Systems
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• v.17 no.3
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• pp.135-152
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• 2008

Basically within a special regional area, a regional cluster seems to be based on core competencies of individual intra-cluster companies and collaboration among them. Information infrastructure has been emphasized as on one of competitive factors of a regional cluster, and it can be organized using collaboration system architecture integrated with each company's internal systems for efficient supply chain operation. As one of technical methods to prepare the system infrastructure supporting the collaboration of companies in a regional cluster, the Web Services can be effectively used. In this paper, a collaborative information system infrastructure for a regional cluster is suggested within the scope of supply chain management. And the efficiency of the proposed alternative is appraised with the features of a regional cluster.

• Communications of Mathematical Education
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• v.36 no.1
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• pp.89-105
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• 2022

In this research, in order to obtain teaching/learning implications for effective use of questions when teaching number and operation area, the types of questions presented in chapters of number and operation area of 2015 revised elementary math textbooks and the function of questions were compared and analyzed by grade cluster. As a result of this research, the types of questions presented in chapters of number and operation area showed a high percentage of occurrences in the order of reasoning questions, factual questions, and open questions not calling for reasoning in common by grade cluster. And reasoning questions were predominant in all grade clusters. In addition, in all grade clasters, the proportion of questions acting as a function to help guess, invention, and solving problems and questions acting as a function to help mathematical reasoning were relatively high. As such, it can be inferred that the types and functions of the questions presented in chapters of number and operation area are related to the characteristics of the learning content by grade cluster. This research will be able to contribute to the preparation of advanced teaching/learning plans by providing reference materials in the questions when teaching number and operation area.

• Korean Journal of Childcare and Education
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• v.13 no.3
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• pp.39-54
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• 2017

Objective: The purpose of this study was to examine natural groupings of the sub-factors of mother's reaction to children's negative emotions. The natural groupings were as follows; the emotion-coaching-reaction, the emotion-minimizing-reaction and oversensitive reaction. In addition, this paper also investigated individual differences in children's emotion regulation by clusters of sub-factors of mother's reaction to children's negative emotions. Methods: The subjects of this study consisted of 318 children. The data were analyzed using cluster analysis and one-way ANOVA. Results: The results suggested four proper clusters, according to the characteristics of mother's reaction to children's negative emotions. Cluster 1 was categorized as 'child centered-emotion coaching', cluster 2 was categorized as 'oversensitive-emotion coaching comorbid', cluster 3 was categorized as 'acception-emotion minimizing confused' and cluster 4 was categorized as 'emotion minimizing-unsupporting.' Additionally, the differences between Emotion regulations in each cluster showed distinct points of interest. In terms of the maladaptive emotion regulation, cluster 3 showed the highest level followed by cluster 4. And cluster 1 and 2 showed the lowest level. Conclusion/Implications: The results of this study helped to find a deeper understanding of the operation of specific clusters of mother's reaction to children's negative emotion and children's emotion regulation.