Recently, a lot of interest is increased in sensor network which gathers various data through many sensor nodes deployed in wired and wireless network environment. However, because of the limitation in memory, computation, and energy of the sensor nodes, security problem is very important issue. In sensor network, not only the security problem, but also computing power should be seriously considered.In this paper, considering these characteristics, we make the sensor network consist of normal sensor nodes and clusterheaders with enough space and computing power, and propose a group key rekeying scheme adopting PCGR(Predistribution and local Collaborationbased Group Rekeying) for secure group communication. In our proposal, we enhance the security by minimizing the risk to safety of the entire network through verifying the new key value from clusterheader by sensor nodes. That is, to update the group keys, clusterheaders confirm sensor nodes through verifying the information from sensor nodes and send the new group keys back to authentic member nodes.The group keys sent back by the clusterheaders are verified again by sensor nodes. Through this mutual authentication, we can check if clusterheaders are compromised or not. Qualnet simulation result shows that our scheme not only guarantees secure group key rekeying but also decreasesstorage and communication overhead.

In this paper, we compared the user experience according to utilize parallax scrolling technique in web site. For this purpose, we divided subjects into two groups. The subjects of Group1 were given to use web site interface with Parallax scrolling and the Group2 were given to use web site interface with non Parallax scrolling. Then, All Subjects answered the questionnaire of user experience. User experience were evaluated by four entries as Novelty, Esthetics, Usage of Satisfaction, Cheerfulness. Consequently. As a result, the web site interface with Parallax scrolling showed significantly higher score of Novelty, Esthetics, Cheerfulness than the web site interface with non-Parallax scrolling. In this study. we proved that using the parallax scrolling technique in web site interface improves the overall user experience, and suggested to apply as a way to advance the attention and persistency on creating a web site.

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The corporate image is one of the key elements improving competitiveness of the business, and is conveyed to the public through a design management strategy and its activities with design identity. Therefore, it is important to enhance the corporate image through systematic design management. Recently, in the field of communication services, as a technical gap between corporations has been narrowed, and the importance of design has been magnified, more and more corporations have adopted the design management. It is, however, not easy to build and convey the corporate image to the public systematically, because not only do the corporations run a communication service, the corporations face various business areas and targets. In this study, we analyzed the relationship between the intended image of the corporate and users' visual experiences based on the surveys on the case of KT, which pioneered design management and has made outstanding design results. According to the result, KT's strategic image concepts have positive effects on users' visual experience in each subarea of its design identity. In conclusion, it is necessary to narrow the gap between users' experiences and images that a corporate intends to convey through continuous research on users' experiences and improvement in a design management system.