• Journal of the Korea Society of Computer and Information
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• v.18 no.1
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• pp.63-71
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• 2013

In the Cluster-Based Routing Protocol (CBRP) a cluster header in each cluster should be elected. The cluster headers consume energy much more than other member nodes do because they manage and operate all of mobile nodes in their cluster. The traditional CBRP elects a cluster header without considering the remaining electric energy of each node. So, there exist problems that the cluster header has short average lifetime, and a new cluster header should be elected again frequently. In this paper, we propose the improved protocol which prolongs the lifetime of the cluster header, decreases the problem of re-electing the cluster header and enhances the stability of the path. In order to achieve this, when a cluster header is elected in a cluster, the remaining electric energies of all the nodes are compared with one another, and the node with the highest energy is elected as the cluster header. Also, the node with the second highest energy is elected as the second header. If the elected cluster header is unable to perform the role of the cluster header any more because the remaining energy level goes low, it sends a beacon message to neighbor member nodes, then the second header will serve as the cluster header.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.91-105
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• 2010

A wireless sensor network communication technique has been broadly studied with continuous advances in ubiquitous computing environment. Especially, because the resource of the sensor node is limited, it is important to reduce the communication energy by using an energy-efficient routing protocol. The existing cluster-based routing protocols have a problem that they cannot select a cluster head efficiently by randomly choosing a head. In addition, because the existing cluster-based routing protocols do not support the large scale of network, they cannot be used for various applications. To solve the above problems, we, in this paper, propose a new cluster-based routing protocol using representative paths. The proposed protocol constructs an efficient cluster with distributed cluster heads by creating representative paths based on hop count. In addition, a new routing protocol supports multi-hop routing for data communication between a cluster member node and a cluster head as well as between cluster heads. Finally, we show that our protocol outperforms LEACH and Multihop-LEACH in terms of reliability and scalability.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.3
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• pp.416-441
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• 2010

This paper attempts to develop a framework articulating a suite of indicators of cluster development, based upon existing work on the economic geography of clusters, cluster frameworks and indicators and cluster policies. Unlike other work the framework adopted here emphasizes adaptive and proactive roles played by agents, whether individual or collective, within the cluster when understanding it as a learning environment to capture an implication made from adopting the cluster perspective. Some possible indicators are operationalized and suggested even if they are not definitive and exhaustive. The conceptual framework and the specific indicators suggested can provide policy-makers and key stakeholders in clusters with a proper set of tools for measuring the level of cluster development, maneuvering a broader strategic planning exercise for successful cluster development.

• Journal of Korean Clinical Nursing Research
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• v.29 no.3
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• pp.337-347
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• 2023

Purpose: The objectives of this study were to categorize the conflict management types of preceptor nurses and determine the effects of these types on preceptors' role perception and core competencies. Methods: Data was collected from 192 preceptor nurses with at least two years experiences in general hospitals, from July 1 to July 31, 2022. Conflict management type, preceptor role perception, and core competency were investigated using structured instruments. The data was analyzed using K-means cluster analysis, Independent samples t-test, One-way ANOVA with Scheffé's test, and multiple regression analysis. Results: The conflict management types were categorized into four types; comprehensive type (cluster 1), integrating, obliging, compromising type (cluster 2), undifferentiated type (cluster 3) and obliging, avoiding type (cluster 4). The effect of conflict management types on preceptors' role recognition occurred in the following order of cluster 2 (integrating/obliging/compromising type), cluster 1 (comprehensive type), and cluster 4 (obliging/avoiding type). Next, cluster 1 (comprehensive type), cluster 2 (integrating/obliging/compromising type), and cluster 4 (obliging/avoiding type) were shown in the order of the impact on the core competencies of the preceptor. Conclusion: When preceptor nurses use a mixture of various attributes of conflict management evenly, they have been shown to demonstrate effective preceptor role recognition and core competencies. Therefore, it is proposed that future development of conflict management training programs for preceptor nurses should begin with identifying their conflict management type, followed by creating a program that addresses any deficiencies.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.4
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• pp.391-407
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• 2023

The state of Baden-Württemberg has one of the strongest regional economies in Germany and is known as one of the most innovative regions in both Germany and Europe. Clusters have played a central role in innovation strategies. The article analyzes the current cluster policy in Baden-Württemberg. The Baden-Württemberg cluster policy has systematically supported the development of clusters, cluster initiatives, and state-wide networks. It has also provided increasing support to regions in developing and implementing innovation and networking activities. The cluster policy has specifically focused on promoting collaborations across different industries and technologies, as well as implementing measures for internationalization. The goal of the Baden-Württemberg state cluster policy was to professionalize cluster management and improve its quality. The cluster policy in Baden-Württemberg has adopted a bottom-up approach and utilized various measures and instruments to promote dialogue. The cluster policy in Baden-Württemberg has established a dedicated cluster agency responsible for developing strategies and implementing individual measures.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.53.1-53.1
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• 2011

We analyze the halo and galaxy catalogs from the Millennium simulations at redshifts z=0, 0.5, 1 to determine the alignment profiles of cluster galaxies in terms of the matter density correlation coefficient and discuss a cosmological implication our result has for breaking parameter degeneracies. For each selected cluster, we measure the alignment between the major axes of the pseudo inertia tensors from all satellites within cluster's virial radius and from only those satellites within some smaller radius. Then we average the measured values over the similar-mass sample to determine the cluster galaxy alignment profile as a function of top-hat scale difference at each redshift. It is shown that the alignment profile of cluster galaxies is well approximated by a power-law of the nonlinear density correlation coefficient that is independent of the power spectrum normalization and bias factor. The alignment profile of cluster galaxies is found to have higher amplitude and lower power-law index when averaged over the larger-mass sample and to have rather weak redshift-dependence. This result is consistent with the picture that the satellite galaxies retain the memory of the external tidal fields right after merging and infalling into the clusters but they gradually lose the initial alignment tendency as the cluster's relaxation proceeds. Demonstrating that the nonlinear density correlation coefficient varies sensitively with the density parameter and neutrino mass fraction, we discuss a potential power of the cluster galaxy alignment profile as an independent probe of cosmology.

• Korean journal of food and cookery science
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• v.22 no.6 s.96
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• pp.783-791
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• 2006

The consciousness and eating habits of the housekeeper directly influence the stress level and health quality of the household occupants. In Korea, most housewives are in charge of dietary life. Accordingly, their attitudinal clusters toward dietary (eating) life were researched in relation to their stress and health. The research results showed that irregular eating habits cause stress. Therefore, it is necessary for housewives to have a regular eating habit. The results were as follows. The house wives' attitudes toward dietary life were categorized into 5 clusters: regular and speedy overeating, regular and frequent eating, regular and light eating, irregular and light eating, irregular and speedy overeating. The cluster of regular and frequent snacks was 24.3%. The cluster of irregular and speedy overeating caused the most stress. Especially the house wives' group belonging to the cluster of irregular and speedy overeating were under social and emotional stress, while the cluster of regular and light eating and the cluster of irregular and light eating were under concentration stress. The cluster of regular and frequent snacks and the cluster of irregular and light eating had negative effect on their health, while the cluster of regular and speedy overeating had negative effect on their family's health by their social stress.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.290-298
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• 2003

Internet-based computer systems have to provide both high-availability and high-performance. Cluster technology has been used to obtain availability and performance simultaneously Generally, high-availability cluster systems tolerate a failure of a cluster node and cost-effectively solve it. In this paper, we study availability and downtime cost of (n,k) cluster systems. By considering performance, we model state transition of (n,k) cluster systems and apply software rejuvenation technique to improve availability of the system. We find that software rejuvenation can be used to improve availability of (n,k) cluster systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4223-4249
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• 2015

A novel jamming detection technique to detect the presence of jamming in the downstream direction for cluster based wireless sensor networks is proposed in this paper. The proposed technique is deployed in base station and in cluster heads. The proposed technique is novel in two aspects: Firstly, whenever a cluster head receives a packet it verifies whether the source node is legitimate node or new node. Secondly if a source node is declared as new node in the first step, then this technique observes the behavior of the new node to find whether the new node is legitimate node or jammed node. In order to monitor the behavior of the existing node and new node, the second step uses two metrics namely packet delivery ratio (PDR) and received signal strength indicator (RSSI). The rationality of using PDR and RSSI is presented by performing statistical test. PDR and RSSI of every member in the cluster is measured and assessed by the cluster head. And finally the cluster head determines whether the members of the cluster are jammed or not. The CH can detect the presence of jamming in the cluster at member level. The base station can detect the presence of jamming in the wireless sensor network at CH level. The simulation result shows that the proposed technique performs extremely well and achieves jamming detection rate as high as 99.85%.

• Journal of Korea Multimedia Society
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• v.17 no.10
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• pp.1160-1170
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• 2014

Clustering methods are very useful in many fields such as data mining, classification, and object recognition. Both the supervised and unsupervised grouping approaches can classify a series of sample data with a predefined or automatically assigned cluster number. However, there is no constraint on the number of elements for each cluster. Numbers of cluster members for each cluster obtained from clustering schemes are usually random. Thus, some clusters possess a large number of elements whereas others only have a few members. In some areas such as logistics management, a fixed number of members are preferred for each cluster or logistic center. Consequently, it is necessary to design a clustering method that can automatically adjust the number of group elements. In this paper, a k-means based clustering method with a fixed number of cluster members is proposed. In the proposed method, first, the data samples are clustered using the k-means algorithm. Then, the number of group elements is adjusted by employing a greedy strategy. Experimental results demonstrate that the proposed clustering scheme can classify data samples efficiently for a fixed number of cluster members.