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Chang S.K.,Battery R and D LG Chemical | Choi S.,Battery R and D LG Chemical | Ryu J.H.,Korea Polytechnic University
Advanced Energy Materials | Year: 2012

Application targets of lithium ion batteries (LIBs) are moving from smallsized mobile devices of information technology to large-scale electric vehicles (xEVs) and energy storage systems (ESSs). Environmental issues and abruptly increasing power demands are pushing high performance energy storage devices or systems onto markets. LIBs are one of the most potential candidates as the energy storage devices mainly due to their high energy densities with fairly good rate capabilities and a fairly long cycle life. As battery systems become larger in terms of stored energy as well as physical size, the safety concerns should be more seriously cared. Each application target has its own specification so that electrode materials should be chosen to meet requirements of the corresponding application. This report diagnoses the current market trends of LIBs as a primary topic, followed by giving an overview of anode and cathode material candidates of LIBs for xEVs and ESSs based on their electrochemical properties. ©2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Yang S.H.,KAIST | Ko E.H.,KAIST | Jung Y.H.,Korea Polytechnic University | Choi I.S.,KAIST
Angewandte Chemie - International Edition | Year: 2011

Tough shell: Living yeast cells can be simultaneously silica-encapsulated and thiol-functionalized by polycondensation of silicic acid and (3-mercaptopropyl)trimethoxysilane under mild conditions. Various functions such as fluorescent dyes (see picture; green: fluorescein, red: rhodamine), chemical moieties, or proteins, can be introduced to the artificial shell by using maleimide-based coupling reactions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Kim P.S.,Korea Polytechnic University
Engineering Letters | Year: 2013

In this paper, an alternative IEEE 802.21-assisted Proxy Mobile IPv6 (PMIPv6) mechanism is proposed for reducing handover latency and signaling cost in heterogeneous wireless networks. The proposed mechanism comes to support fast vertical handover for the mobile node (MN) irrespective of the presence or absence of Media Independent Handover (MIH) functionality as well as IP mobility functionality. That is, the MN does not need to be participated in any MIH related signaling for handover procedure, which can be consistent with the essential objective of the PMIPv6. The base station with MIH functionality performs handover on behalf of the MN. Therefore, the proposed mechanism can reduce burden and power consumption of MNs with limited resource and battery power. In addition, analytical evaluation, experiment and simulation show that the proposed mechanism can outperform the existing mechanism in terms of handover latency and total number of over-the-air signaling messages. Thus, the proposed mechanism can be expected to reduce the packet loss and the bandwidth consumption of wireless links during handover procedure comparing with the existing mechanism. Source

Ahmad N.,Wuhan University of Technology | Younus H.A.,Wuhan University of Technology | Younus H.A.,Fayoum University | Chughtai A.H.,Wuhan University of Technology | And 3 more authors.
Chemical Society Reviews | Year: 2015

New well-designed materials are highly demanded with the prospect of versatile properties, offering successful applications as alternates to conventional materials. Major new insights into metal-organic self-assembled structures assisting biochemical purposes have recently emerged. Metal-organic polyhedral cages are highlighted as new research materials to be used for therapeutic, sensing and imaging, purposes etc. This tutorial review covers achievements in the biochemical applications of these multinuclear complexes. Examples of their ability to aid the ionic transport, biomolecular sensing, imaging, and drug delivery are presented. © The Royal Society of Chemistry 2015. Source

Kim H.,Korea Polytechnic University
Engineering Failure Analysis | Year: 2011

A crack of the fourth stage blade in a low-pressure turbine of a 500. MW steam turbine is studied. From non-destructive inspection, the crack was found at the leading edge vane of the fourth stage blade. Material composition analysis, hardness measurement and microstructure analysis were performed to study the cause and process of the cracked blade. On further examination using the replication of the cracked surface for the blade vane, the crack was induced by corrosion pits. It is assumed that the causes of the corrosion pits are the induction of seawater from the condenser tube that has small leakage, and improper water treatment. It is shown that the corrosion pits acted as stress concentration site and facilitated crack initiation under cyclic loading experienced during normal operation of the blade. From the fracture surface of the blade, it is concluded that the crack is initiated from the corrosion pits at the leading edge of the blade vane, and propagated inside by fatigue due to the vibration of the blade. © 2010 Elsevier Ltd. Source

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