Suigen, South Korea
Suigen, South Korea

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Kim J.,Dankook University | Heo H.Y.,Dankook University | Heo H.Y.,Central Randnter | Jung T.H.,Dankook University | And 4 more authors.
Polymer (Korea) | Year: 2011

The physical properties of poly (ethylene 2,6-naphthalate) (PEN) copolymers were studied. PEN copolymers were synthesized successfully from the mixtures of ethylene glycol (EG), 1,3-propanediol (PD) and 1,4-butanediol (BD) with 2,6-dimethyl naphthalene dicarboxylate. The results indicated that PEN copolymers showed an amorphous state when the content of BD(PD) in applied EG/BD(EG/PD) mixtures was less than 40% during the polycondensation. As a result, the lowering of thermal properties, orientation, and mechanical properties was found, however, the dimensional stability was improved. This is a promising result to apply the synthesized PEN copolymers as flexibles substrates.

Suresh S.,Nanyang Technological University | Run C.,Korea University | Kim H.J.,Korea University | Robertazzi T.G.,State University of New York at Stony Brook | Kim Y.-I.,Central Randnter
IEEE Transactions on Aerospace and Electronic Systems | Year: 2012

Scheduling divisible loads with the nonlinear computational complexity is a challenging task as the recursive equations are nonlinear and it is difficult to find closed-form expression for processing time and load fractions. In this study we attempt to address a divisible load scheduling problem for computational loads having second-order computational complexity in a master-slave paradigm with nonblocking mode of communication. First, we develop algebraic means of determining the optimal size of load fractions assigned to the processors in the network using a mild assumption on communication-to- computation speed ratio. We use numerical simulation to verify the closeness of the proposed solution. Like in earlier works which consider processing loads with first-order computational complexity, we study the conditions for optimal sequence and arrangements using the closed-form expression for optimal processing time. Our finding reveals that the condition for optimal sequence and arrangements for second-order computational loads are the same as that of linear computational loads. This scheduling algorithm can be used for aerospace applications such as Hough transform for image processing and pattern recognition using hidden Markov model (HMM). © 2006 IEEE.

Cho C.,Samsung | Lee C.,EzVille Inc. | Ryoo J.,Central Randnter | Choo H.,Hongik University
IEEE Antennas and Wireless Propagation Letters | Year: 2011

In this letter, we propose a novel UHF planar near-field antenna for the application of RFID item-level tagging. The proposed antenna was designed to have a strong and uniform mbiH z-field over a broad antenna aperture to identify the various items with stable reading performance. To obtain a strong near H z-field, two coupled patches are employed along with a microstrip-line feed, resulting in average mbiH z of - 15 dBA/m on antenna aperture (30 × 30 × 10cm 3). We also measured the reading range, and it confirmed that the proposed antenna is suitable for a commercial RFID smart-shelf application. © 2006 IEEE.

Back C.-K.,Central Randnter | Kim T.-J.,University of Suwon | Choi N.-S.,Ulsan National Institute of Science and Technology
Journal of Materials Chemistry A | Year: 2014

A highly promising anode material with an amorphous SiOx nanostructure finely impregnated with carbon nanofibers is presented. The nanostructure material has a unique integral feature in that carbon nanofibers smaller than several nm in diameter are finely dispersed in amorphous SiO x media in an aligned manner. The synthetic route to fabricate the nanostructure is very simple and easy, using natural porous silicate, sepiolite, activated through the process of sintering and acid treatments on carbon source-loaded sepiolite nanocomposites. Upon the treatments, the nanocomposite material is changed in respect of its structure and chemical composition from crystalline Mg silicate to the carbon nanofiber-impregnated amorphous SiO x phase (CNF-SiOx nanostructure), and the electrochemical activity is greatly improved. The CNF-SiOx nanostructure exhibits excellent electrochemical performance with a reasonably high capacity of approximately 720 mA h g-1 for a current density of 70 mA g -1 (C/10 rate) and outstanding rate capability with a capacity retention of 96.8% for a current density of 700 mA g-1 and 87% at 1400 mA g-1 relative to that at 35 mA g-1, even at a high electrode loading level above 8 mg cm-2. The cycling performance is also very stable, with a capacity retention of 94.7% over 50 cycles at a rate of 350 mA g-1 and with a Coulombic efficiency above 99%. This journal is © the Partner Organisations 2014.

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