• Title/Summary/Keyword: U.J.S.

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A Study on the Gas Sensing Properties of $SnO_2$ Gas Sensors Fabricated by Sol-Gel Method (졸-겔법으로 제작된 $SnO_2$ 가스센서의 가스 감응 특성에 관한 연구)

  • Jang, K.U.;Kim, M.H.;Lee, W.J.;Kim, T.W.;Lee, H.S.;Chung, D.H.;Ahn, J.H.;Lee, J.U.;Kim, S.K.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.591-592
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    • 2005

  • PTC Thermistors specimens were fabricated by added $MnO_2$ as donors, and $Nb_2O_5$ as acceptors and sintered $1250^{\circ}C$/2hrs. Average grain size decreased with increased in added $MnO_2$, and increased with added in $Nb_2O_5$. But, appeared liquid phase as $Bi_2O_3$ and $TiO_2$, affect to grain growth. XRD result, peak strength waslowed then crystallization not well, but, secondary phase were not showed all specimens. All specimens resistance were so high, about $40M\Omega$ over, couldn't measured to those resistance and doesn't appear PTCR effect.

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ON STABILITY PROBLEMS WITH SHADOWING PROPERTY AND ITS APPLICATION

  • Chu, Hahng-Yun;Han, Gil-Jun;Kang, Dong-Seung
    • Bulletin of the Korean Mathematical Society
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    • v.48 no.4
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    • pp.673-688
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    • 2011

  • Let $n{\geq}2$ be an even integer. We investigate that if an odd mapping f : X ${\rightarrow}$ Y satisfies the following equation $2_{n-2}C_{\frac{n}{2}-1}rf\(\sum\limits^n_{j=1}{\frac{x_j}{r}}\)\;+\;{\sum\limits_{i_k{\in}\{0,1\} \atop {{\sum}^n_{k=1}\;i_k={\frac{n}{2}}}}\;rf\(\sum\limits^n_{i=1}(-1)^{i_k}{\frac{x_i}{r}}\)=2_{n-2}C_{{\frac{n}{2}}-1}\sum\limits^n_{i=1}f(x_i),$ then f : X ${\rightarrow}$ Y is additive, where $r{\in}R$. We also prove the stability in normed group by using shadowing property and the Hyers-Ulam stability of the functional equation in Banach spaces and in Banach modules over unital C-algebras. As an application, we show that every almost linear bijection h : A ${\rightarrow}$ B of unital $C^*$-algebras A and B is a $C^*$-algebra isomorphism when $h(\frac{2^s}{r^s}uy)=h(\frac{2^s}{r^s}u)h(y)$ for all unitaries u ${\in}$ A, all y ${\in}$ A, and s = 0, 1, 2,....

  • https://doi.org/10.4134/BKMS.2011.48.4.673 인용 PDF KSCI

Development of the OSGi-based USB Terminal System for U-learning (U-learning을 위한 OSGi에 기반한 USB 단말기 시스템 개발)

  • Kim, Hee-Sun;Kim, Jee-Hong;Lee, Chang-Goo
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.12
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    • pp.1252-1256
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    • 2007

  • U-learning (ubiquitous learning) systems, which deliver learning materials anytime and anywhere, allow learners to watch live lectures on PDAs, tablet PCs and notebook computers via broadband and wireless Internet. These systems have various problems; first, terminal devices are expensive, and it is difficult to maintain their efficiencies. Secondly, Internet does not guarantee quality of service (QoS), and in general it does not provide real-time services. Finally, the security of these systems is weaker in a local network than in an external network. The USB-based terminal system based on the OSGi service platform was designed as a ubiquitous system, in order to solve those problems. The USB terminals, used in this system, are inexpensive, and it is easy to maintain their performances. Also, this system solves the problems of security in a local network and provides guaranteed QoS. To accomplish this, the number of USB terminals connected to the system has to be limited according to the formula proposed in our paper. This system uses the OSGi specification as a middleware. It supports the discovery mechanism of the USB terminals, maintenance and administration of the system. Finally, this paper shows a driver's license testing system as an example u-learning application1.

  • https://doi.org/10.5302/J.ICROS.2007.13.12.1252 인용 PDF KSCI