• International Journal of Internet, Broadcasting and Communication
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• v.7 no.1
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• pp.75-92
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• 2015

This paper presents the application of the bond valence method to estimate the valence charge distribution in several perovskite systems: $La_{{\tilde{1}}x}Pb_xMnO_3$ (x=0.1-0.5), $La_{0.6}Sr_{0.{\tilde{4}}x}Ti_xMnO_3$ (x=0.0-0.25) and $La_{{\tilde{1}}x}Sr_xCoO_3$ (x=0.1-0.5); the reviewing of their crystal structures is also incorporated. The results showed the failure of the elastic bonding mechanism in all studied systems and revealed the general deficit of the valence charge in their unit cells. This valence deficit was not associated with the structural defects and was not equally localized in all coordination spheres. As the content of substitution increased, the charge deficit declined systematically from balanced level, signifying the transfer of valence charge from the ${\tilde{B}}O_6$ to ${\tilde{A}}O_{12}$ spheres. This transfer depended on the valence deviation of spheres and the average reached near 2 electron per unit cell. The possible impact of the limitted accuracy of the available structural data on the bond valence results has also been considered.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.1
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• pp.203-213
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• 2014

In Korea, a cooperation charge on conservation of ecosystem is imposed to prevent indiscriminate development. The total amount of this charge is determined by multiplying the size of the destroyed area by a value per unit area and the area index within 5 billion won. Since 2001, the charge per unit area has been determined to be $250won/m^2$. In this study, we estimated the unit value of ecosystem services per year using benefit transfer method, with a focus on forest resources. According to our results, forest resources have a value of about $3,500won/m^2$ per year. When the non-use value is subtracted, that figure becomes approximately $1,300won/m^2$. If this value incorporates the unit value of the cooperation charge on conservation of ecosystem, it will increase. To comply with the original intent of the cooperation charge on conservation of ecosystem, the fund must be used to improve ecosystem services, including the restoration of a destroyed area or the purchase of new land.

• Journal of Adhesion and Interface
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• v.21 no.4
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• pp.129-134
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• 2020

Understanding charge trapping at the interface between conjugated semiconductor and polymer dielectric basically gives insight into the development of long-term stable organic field-effect transistors (OFET). Here, the charge transport properties of OFETs using polymer dielectric with various molecular weights (MWs) have been investigated. The conjugated semiconductor, pentacene exhibited morphology and crystallinity, insensitive to MWs of polymethyl methacrylate (PMMA) dielectric. Consequently, transfer curves and field-effect mobilities of as-prepared devices are independent of MWs. Under bias stress in humid environment, however, the drain current decay as well as transfer curve shift are found to increase as the MW of PMMA decreases (MW effect). The charge trapping induced by MW effect is irreversible, that is, the localized charges are difficult to be delocalized. The MW effect is caused by the variation in the density of polymer chain ends in the PMMA: the free volumes at the PMMA chain ends act as charge trap sites, corresponding to drain current decay depending on MWs of PMMA.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.453-459
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• 2013

In phtosynthetic light harvesting complexes, the electronic transition energies of chlorophylls are influenced by the Coulombic interaction with nearby molecules. Variation of the interactions caused by structural inhomogeneity in biological environment results in a distribution of disordered electronic transition energies of chlorophylls. In order to provide a practical guide to predict qualitative tendency of such distribution, we model four porphyrin derivatives including chlorophyll a molecule interacting with an external positive charge and calculate their transition energies using the time dependent density functional method. It is found that ${\pi}-{\pi}^*$ transition energies of the molecules are generally blue-shifted by the charge because this stabilizes occupied molecular orbitals to a greater extent than unoccupied ones. Furthermore, new transitions in the visible region emerge as a result of the red-shift in energy of an unoccupied Mg orbital and it is suggested that light-induced electron transfer may occur from the tetrapyrrole ring to the central magnesium when the molecules are interacting with a positive charge.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.15-15
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• 1997

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.274-274
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• 2007

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.32-32
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• 1996

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.907-909
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• 2004

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.11-11
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• 1995

• Bulletin of the Korean Chemical Society
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• v.16 no.1
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• pp.69-71
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• 1995