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Park M.,Kangnam University | Lee T.-S.,KISTI
Electronic Library | Year: 2016

Purpose ? This study aims at a longitudinal understanding of the user?system interactions from the context of science and technology at a query level. Design/methodology/approach ? The authors quantitatively analyzed log data sets culled from more than 24,820,416 queries submitted by users of a national scientific and technical information system, collected in 2008-2011. Findings ? In the fields of science and technology, the user search behaviors and patterns have remained stable. User queries are short and simple. In all, 80 per cent of the queries are made up of one-three terms. The length of query on a scholarly information system in the fields of science and technology is different from that of Web search. The former is longer than the latter. Search topics have shifted fast. "FUEL BATTERY", "NANO", "OLED", "CAR", "ROBOT" and "SMARTPHONE" were high-ranked queries from 2008 to 2011. It was found that the time to determine whether the users will stay on the site took about 10 seconds on average from the time of visit. If the users viewed the results of a list generated by the search query and took any action, such as detailed view, export or full-text download, most of them stayed more than 10 minutes on average. Originality/value ? Longitudinal user research using a query analysis helps to understand the information needs and behavioral patterns of users on information systems related to a specific field and those based on the Web. It also brings insights into the past, present and future events of a field. In other words, it plays a role as a mirror that reflects the flow of time. In the long run, it will be an historic asset. In the future, user studies using a query analysis need to be carried out from various (e.g. social, cultural or other academic disciplines) long-term perspectives on a continuous basis. © 2016 Emerald Group Publishing Limited. Source


Seo D.W.,KISTI | Lee J.Y.,Chonnam National University
Expert Systems with Applications | Year: 2013

Several studies have been carried out on augmented reality (AR)-based environments that deal with user interfaces for manipulating and interacting with virtual objects aimed at improving immersive feeling and natural interaction. Most of these studies have utilized AR paddles or AR cubes for interactions. However, these interactions overly constrain the users in their ability to directly manipulate AR objects and are limited in providing natural feeling in the user interface. This paper presents a novel approach to natural and intuitive interactions through a direct hand touchable interface in various AR-based user experiences. It combines markerless augmented reality with a depth camera to effectively detect multiple hand touches in an AR space. Furthermore, to simplify hand touch recognition, the point cloud generated by Kinect is analyzed and filtered out. The proposed approach can easily trigger AR interactions, and allows users to experience more intuitive and natural sensations and provides much control efficiency in diverse AR environments. Furthermore, it can easily solve the occlusion problem of the hand and arm region inherent in conventional AR approaches through the analysis of the extracted point cloud. We present the effectiveness and advantages of the proposed approach by demonstrating several implementation results such as interactive AR car design and touchable AR pamphlet. We also present an analysis of a usability study to compare the proposed approach with other well-known AR interactions. © 2012 Elsevier Ltd. All rights reserved. Source


Park S.B.,KISTI
Advances in Multimedia | Year: 2015

With the explosive growth of various multimedia contents, digital archives are used to store those contents accordingly. In contrast to the traditional storage systems in which data lifetime is measured in months or years, data lifetime in the archive is measured in decades. This longevity of contents causes new security issues that threat the archive systems. In this paper, we discuss these new security issues in perspective. And we suggest some security requirements for digital archives. © 2015 Sang Bae Park. Source


Hansen J.,KISTI | Lee B.-H.,Sogang University | Park C.,Sogang University | Yeom D.-H.,Sogang University | Yeom D.-H.,Kyoto University
Classical and Quantum Gravity | Year: 2013

In this paper, we investigate the dynamics inside and outside of black-branes in anti de Sitter space by numerical simulations using double-null formalism. We prepare a charged planar matter shell which, due to a negative cosmological constant, collapses and dynamically forms a black-brane with an apparent horizon, a singularity and a Cauchy horizon. The gravitational collapse cannot form a naked overcharged black-brane and hence weak cosmic censorship is safe. Although mass inflation occurs, the effect is much milder than in the case of charged black holes; hence, strong cosmic censorship seems not to be safe. We observed the scalar field dynamics outside the horizon. There should remain a non-trivial scalar field combination - 'charge cloud' - between the horizon and the boundary. This can give some meaning in terms of the AdS/CFT correspondence. © 2013 IOP Publishing Ltd. Source


Hansen J.,KISTI | Yeom D.-H.,National Taiwan University
Journal of Cosmology and Astroparticle Physics | Year: 2015

We investigate the relation between the existence of mass inflation and model parameters of string-inspired gravity models. In order to cover various models, we investigate a Brans-Dicke theory that is coupled to a U(1) gauge field. By tuning a model parameter that decides the coupling between the Brans-Dicke field and the electromagnetic field, we can make both of models such that the Brans-Dicke field is biased toward strong or weak coupling directions after gravitational collapses. We observe that as long as the Brans-Dicke field is biased toward any (strong or weak) directions, there is no Cauchy horizon and no mass inflation. Therefore, we conclude that to induce a Cauchy horizon and mass inflation inside a charged black hole, either there is no bias of the Brans-Dicke field as well as no Brans-Dicke hair outside the horizon or such a biased Brans-Dicke field should be well trapped and controlled by a potential. Source

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