• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.05a
• /
• pp.241-244
• /
• 2012

In mobile ad-hoc networks, it should be the most important issue to reduce the power consumption of communications, because the resource of a node is limited in these networks. In existing cluster-based routing protocols, cluster headers participate in almost all communication processes. Therefore the lifetime of the cluster header is shortened and it does not have the effective route. In the proposed cluster-based routing protocol, the cluster header transmits a control packet which gives the route information to member nodes. This makes that the cluster header decreases the number of participating in communications, and that node members do not have to communicate trough the cluster header. This results in extending the lifetime of the cluster header, and having the effective route, data transmission rate and improved stability of routes.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.5
• /
• pp.195-202
• /
• 2008

In this paper, To improve the effectiveness of security enforcement, the first contribution in this work is that we present a clustered heterogeneous WSN(Wareless Sensor Network) architecture, composed of not only resource constrained sensor nodes, but also a number of more powerful high-end devices acting as cluster heads. Compared to sensor nodes, a high-end cluster head has higher computation capability, larger storage, longer power supply, and longer radio transmission range, and it thus does not suffer from the resource scarceness problem as much as a sensor node does. A distinct feature of our heterogeneous architecture is that cluster heads are equipped with TC(trusted computing) technology, and in particular a TCG(Trusted Computing Group) compliant TPM (Trusted Platform Module) is embedded into each cluster head. According the TCG specifications, TPM is a tamper-resistant, self-contained secure coprocessor, capable of performing cryptographic functions. A TPM attached to a host establishes a trusted computing platform that provides sealed storage, and measures and reports the integrity state of the platform.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.7
• /
• pp.2649-2666
• /
• 2015

In the dynamic cloud computing environment, to ensure, under the terms of service-level agreements, the maximum efficiency of resource utilization, it is necessary to investigate the online dynamic management of virtual machine resources and their operational application systems/components. In this study, the feasibility and properties of the division of virtual machine resources on the cloud platform, using the virtual machine cluster as the management unit, are investigated. First, the definitions of virtual machine clusters are compared, and our own definitions are presented. Then, the feasibility of division using the virtual machine cluster as the management unit is described, and the isomorphism and reconfigurability of the clusters are proven. Lastly, from the perspectives of clustering and cluster segmentation, the dynamics of virtual machines are described and experimentally compared. This study aims to provide novel methods and approaches to the optimization management of virtual machine resources and the optimization configuration of the parameters of virtual machine resources and their application systems/components in large-scale cloud computing environments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37A no.9
• /
• pp.772-779
• /
• 2012

In the current MANET, DOS or DDOS attacks are increasing, but as MANET has limited bandwidth, computational resources and battery power, the existing traceback mechanisms can not be applied to it. Therefore, in case of traceback techniques being applied to MANET, the resource of each node must be used efficiently. However, in the traceback techniques applied to an existing ad hoc network, as a cluster head which represents all nodes in the cluster area manages the traceback, the overhead of the cluster head shortens each node's life. In addition, in case of multi-hop clustering, as one Cluster head manages more node than one, its problem is getting even worse. This paper proposes TNA(Traceback against Network Attacks) based on multihop clustering using the depth of tree structure in order to reduce the overhead of distributed information management.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.6
• /
• pp.1565-1585
• /
• 2012

The characteristics of ad hoc networks, such as the absence of infrastructure, a dynamic topology, a shared wireless medium and a resource-constrained environment pose various security challenges. Most previous studies focused on the detection of misbehavior after it had occurred. However, in this paper we propose a new way of thinking to evade the occurrence of misbehavior. In our scheme, we firstly present a clustering algorithm that employs a powerful analytic hierarchy process methodology to elect a clusterhead for each cluster. The clusterhead in each cluster is then allowed to assign the backoff values to its members, i.e., originators, rather than permitting the originators to choose the backoff values by themselves. Through this media access control layer misbehavior detection mechanism, the misuse of the backoff in the media access control layer in the 802.11 distributed coordination function can be detected.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.4
• /
• pp.1692-1711
• /
• 2016

Energy is a scarce resource in wireless sensor networks (WSNs). A variety of clustering protocols for WSNs, such as the zone-based stable election protocol-enhanced (ZSEP-E), have been developed for energy optimization. The ZSEP-E is a heterogeneous zone-based clustering protocol that focuses on unbalanced energy consumption with parallel formation of clusters in zones and election of cluster heads (CHs). Most ZSEP-E research has assumed probabilistic election of CHs in the zones by considering the maximum residual energy of nodes. However, studies of the diverse CH election parameters are lacking. We investigated the performance of the ZSEP-E in such scenarios using a fuzzy logic approach based on three descriptors, i.e., energy, density, and the distance from the node to the base station. We proposed an efficient ZSEP-E scheme to adapt and elect CHs in zones using fuzzy variables and evaluated its performance for different energy levels in the zones.

• The Journal of Economics, Marketing and Management
• /
• v.6 no.4
• /
• pp.17-27
• /
• 2018

Purpose - As Korea is reaching a post-aged society, the number of chronic illness is increasing, and the demand for rehabilitation medical device is growing. Although there is high potential for the growth in rehabilitation industry, because most of the related companies in Korea are relatively small, lacking capital or R&D resource, it is difficult for them to create an innovative product, and currently most of the high-tech equipments are imported. Therefore a medical device cluster, where business, research, medical institutes and universities may work cooperatively to enhance research development and solve issues is necessary for future development. Research design, data, methodology - In this method we have done a literature review of the rehabilitation industry and industrial cluster. Based on the studies, we have conducted an exploratory factor analysis by studying examples of foreign and domestic medical clusters and drawing success factors in forming a medical cluster. Next based on the studies we have conducted a survey to domestic medical device companies to find their difficulties and needs to form a successful medical device cluster. Results - This paper provides both theoretic review on success factors of forming a medical device cluster and practical analysis using case study and survey. Conclusion - The significance of this paper is that based on the literature review, we have compared actual examples of domestic/foreign medical clusters and drawn difference and coincidence between literature and actual cluster success factor. We were also able to conduct a survey on actual medical device companies and through the results we were able to search difficulties and necessities of medical device companies.

• Journal of Korean Society of Rural Planning
• /
• v.12 no.1 s.30
• /
• pp.37-48
• /
• 2006

The objectives of this study were to develop an evaluation method of regional vulnerability to agricultural drought and to classify the vulnerability patterns. In order to test the method, 24 city or county areas of Gyeonggi-do were chose. First, statistic data and digital maps referred for agricultural drought were defined, and the input data of 31 items were set up from 5 categories: land use factor, water resource factor, climate factor, topographic and soil factor, and agricultural production foundation factor. Second, for simplification of the factors, principal component analysis was carried out, and eventually 4 principal components which explain about 80.8% of total variance were extracted. Each of the principal components was explained into the vulnerability components of scale factor, geographical factor, weather factor and agricultural production foundation factor. Next, DVIP (Drought Vulnerability Index for Paddy), was calculated using factor scores from principal components. Last, by means of statistical cluster analysis on the DVIP, the study area was classified as 5 patterns from A to E. The cluster A corresponds to the area where the agricultural industry is insignificant and the agricultural foundation is little equipped, and the cluster B includes typical agricultural areas where the cultivation areas are large but irrigation facilities are still insufficient. As for the cluster C, the corresponding areas are vulnerable to the climate change, and the D cluster applies to the area with extensive forests and high elevation farmlands. The last cluster I indicates the areas where the farmlands are small but most of them are irrigated as much.

• Journal of Environmental Science International
• /
• v.18 no.8
• /
• pp.899-910
• /
• 2009

We classified wind sectors according to the wind features in South Korea. In order to get the information of wind speed and wind direction, we used and improved on the atmospheric numerical model. We made use of detailed topographical data such as terrain height data of an interval of 3 seconds and landuse data produced at ministry of environment, Republic of Korea. The result of simulated wind field was improved. We carried out the cluster analysis to classify the wind sectors using the K-means clustering. South Korea was classified as 8 wind sectors to the annual wind field.

• Environmental and Resource Economics Review
• /
• v.17 no.4
• /
• pp.691-717
• /
• 2008

The Kyoto Mechanisms allows a supplementary means for compliance, CDM(Clean Development Mechanism) and JI(Joint Implementation) projects. The investment in CDM projects is increasing rapidly as the first implementation period began in 2008. This paper seeks to determine factors affecting the price of primary CER using UNFCCC CDM Project Development Document(PDD) data. This study employs the Cluster analysis and the GLS(Generalized Least Squares) method.