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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.

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.

Jeong D.-H.,KISTI | Kil S.-C.,KISTI | Nam S.W.,KISTI
Journal of Korean Institute of Metals and Materials | Year: 2014

Composite materials are artificially engineered materials composed of a matrix and filler with reinforcing agents embedded in the matrix to enhance various properties. These days, as the demand for lightweight and high performance composite materials is increasing, especially in the field of transportation, many efforts are focused on research activity in the area of carbon nanotube (CNT) composite materials. In this review paper, the first discovery of the CNT is considered and the various properties of CNTs, such as mechanical (stiffness, tensile strength, damping), electrical and thermal properties, are briefly explained. For the evaluation of the recent lightweight and high performance CNT composites research trends, papers published within the last 10 years are selected. The role of the strengthener CNTs (SWCNTs and MWCNTs) and several different polymers (epoxy resin, polypropylene and polystyrene) for the matrix materials are considered in the evaluation. It is found that many research activities for the modification of the CNT surface focus on the uniform distribution of the CNTs in the matrix. Research work for the improvement of the binding energy between CNTs and polymers is also emphasized to optimize the mechanical behaviors. Copyright © The Korean Institute of Metals and Materials.

Hansen J.,KISTI | Yeom D.-H.,Kyoto University | Yeom D.-H.,National Taiwan University
Journal of High Energy Physics | Year: 2014

We investigate gravitational collapses of charged black holes in string-inspired gravity models, including dilaton gravity and braneworld model, as well as f (R) gravity and the ghost limit. If we turn on gauge coupling, the causal structures and the responses of the Brans-Dicke field depend on the coupling between the charged matter and the Brans-Dicke field. For Type IIA inspired models, a Cauchy horizon exists, while there is no Cauchy horizon for Type I or Heterotic inspired models. For Type IIA inspired models, the no-hair theorem is satisfied asymptotically, while it is biased to the weak coupling limit for Type I or Heterotic inspired models. Apart from string theory, we find that in the ghost limit, a gravitational collapse can induce inflation by itself and create one-way traversable wormholes without the need of other special initial conditions. © The Authors.

Wu D.,Mount Sinai Medical Center | Wu D.,Chonbuk National University | Lee D.,Chonbuk National University | Sung Y.K.,KISTI | Sung Y.K.,Dongguk University
Respiratory Research | Year: 2011

There is mounting evidence that pulmonary arterial hypertension (PAH), asthma and chronic obstructive pulmonary disease (COPD) share important pathological features, including inflammation, smooth muscle contraction and remodeling. No existing drug provides the combined potential advantages of reducing vascular- and bronchial-constriction, and anti-inflammation. Vasoactive intestinal peptide (VIP) is widely expressed throughout the cardiopulmonary system and exerts a variety of biological actions, including potent vascular and airway dilatory actions, potent anti-inflammatory actions, improving blood circulation to the heart and lung, and modulation of airway secretions. VIP has emerged as a promising drug candidate for the treatment of cardiopulmonary disorders such as PAH, asthma, and COPD. Clinical application of VIP has been limited in the past for a number of reasons, including its short plasma half-life and difficulty in administration routes. The development of long-acting VIP analogues, in combination with appropriate drug delivery systems, may provide clinically useful agents for the treatment of PAH, asthma, and COPD. This article reviews the physiological significance of VIP in cardiopulmonary system and the therapeutic potential of VIP-based agents in the treatment of pulmonary diseases. © 2011 Wu et al; licensee BioMed Central Ltd.

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.

Ryu S.,KISTI | Ganis G.,CERN
Journal of Physics: Conference Series | Year: 2012

The PROOF benchmark suite is a new utility suite of PROOF to measure performance and scalability. The primary goal of the benchmark suite is to determine optimal configuration parameters for a set of machines to be used as PROOF cluster. The suite measures the performance of the cluster for a set of standard tasks as a function of the number of effective processes. Cluster administrators can use the suite to measure the performance of the cluster and find optimal configuration parameters. PROOF developers can also utilize the suite to help them measure, identify problems and improve their software. In this paper, the new tool is explained in detail and use cases are presented to illustrate the new tool.

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.

Jung Y.,KISTI | Kim J.,KISTI | So M.,KAIST | Kim H.,KISTI
Scientometrics | Year: 2015

In this study, we analysed the statistical association between e-journal use and research output at the institution level in South Korea by performing comparative and diachronic analyses, as well as the analysis by field. The datasets were compiled from four different sources: national reports on research output indicators in science fields, two statistics databases on higher education institutions open to the public, and e-journal usage statistics generated by 47 major publishers. Due to the different data sources utilized, a considerable number of missing values appeared in our datasets and various mapping issues required corrections prior to the analysis. Two techniques for handling missing data were applied and the impact of each technique was discussed. In order to compile the institutional data by field, journals were first mapped, and then the statistics were summarized according to subject field. We observed that e-journal use exhibited stronger correlations with the number of publications and the times cited, in contrast to the number of undergraduates, graduates, faculty members and the amount of research funds, and this was the case regardless of the NA handling method or author type. The difference between the maximum correlation for the amount of external research funding with two average indicators and that of the correlation for e-journal use were not significant. Statistically, the accountability of e-journal use for the average times cited per article and the average JIF was quite similar with external research funds. It was found that the number of e-journal articles used had a strong positive correlation (Pearson’s correlation coefficients of r > 0.9, p < 0.05) with the number of articles published in SCI(E) journals and the times cited regardless of the author type, NA handling method or time period. We also observed that the top-five institutions in South Korea, with respect to the number of publications in SCI(E) journals, were generally across a balanced range of academic activities, while producing significant research output and using published material. Finally, we confirmed that the association of e-journal use with the two quantitative research indicators is strongly positive, even for the analyses by field, with the exception of the Arts and Humanities. © 2015, Kluwer Academic Publishers.

News Article | November 17, 2015

The Dept. of Supercomputing Modeling and Simulation at the Korea Institute of Science and Technology Information (KISTI) runs a modeling and simulation program that offers Korean SMEs the opportunity to develop high-quality products using the supercomputers at KISTI. Through open calls, the project selects about 40 engineering projects of SMEs every year and provides technical assistance, access to the supercomputers, and the appropriate modeling and simulation software technology such as CFD, FEA, etcetera. From 2004 to date, the project has assisted about 420 SMEs. The project recently assisted the development of a slow juicer made by NUC by improving the juice extraction rate from 75 to 82.5 percent through numerical shape optimization of a screw by using the “Tachyon II” supercomputer and fluid/structural analysis. This helped sales dramatically increase from about $1.9 million in 2010 to $96 million 2014, and the company has hired 150 new employees through building the additional manufacturing lines.

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