• Title/Summary/Keyword: Hybrid functional

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Highly efficient white organic light-emitting diodes using hybrid-spacer or/and codoped blue emitting layers

  • Seo, Ji-Hoon;Kim, Gu-Young;Hyung, Gun-Woo;Lee, Kum-Hee;Kim, You-Hyun;Kim, Woo-Young;Yoon, Seung-Soo;Kim, Young-Kwan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1219-1221
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    • 2008
  • The Authors have demonstrated highly efficient white organic light-emitting diodes using hybrid-spacer which was inserted between each emitting layer or/and codoped blue emitting layers with the different functional material. The characteristics of WOLEDs showed the maximum external quantum efficiency of 13.8%, power efficiency of 33.66 lm/W, and Commission Internationale de I'Eclairage coordinates of (x=0.36, y=0.37), respectively.

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Fluorine-Induced Local Magnetic Moment in Graphene: A hybrid DFT study

  • Kim, Hyeon-Jung;Jo, Jun-Hyeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.127.1-127.1
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    • 2013
  • Recent experimental evidence that fluorinated graphene creates local magnetic moments around F adatoms has not been supported by semilocal density-functional theory (DFT) calculations where the adsorption of an F adatom induces no magnetic moment in graphene. Here, we show that such an incorrect prediction of the nonmagnetic ground state is due to the self-interaction error inherent in semilocal exchange-correlation functionals. The present hybrid DFT calculation for an F adatom on graphene predicts not only a spin-polarized ground state with a spin moment of ${\sim}1{\mu}_B$, but also a long-range spin polarization caused by the bipartite nature of the graphene lattice as well as the induced spin polarization of the graphene states. The results provide support for the experimental observations of local magnetic moments in fluorinated graphene.

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Fabrication of Pre-Exfoliated Clay Masterbatch via Exfoliation-Adsorption of Polystyrene Nanobeads

  • Khvan, Svetlana;Kim, Jun-Kyung;Lee, Sang-Soo
    • Macromolecular Research
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    • v.15 no.1
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    • pp.51-58
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    • 2007
  • The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.

Hybrid Representations for Enveloping Modeling in Gearing

  • Voznyuk, Roman
    • International Journal of CAD/CAM
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    • v.3 no.1_2
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    • pp.13-17
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    • 2003
  • Hybrid method of representing geometric entities as combination of boundary (B-rep) and functional (F-rep) representations is presented which can be used as a basis of solid modeling kernel. It contains whole functionality of classic B-rep kernel, and also supports enveloping (sweep of solid body). Principles and keysolutions are considered. Example of a real task that comes from gearing is provided.

Chromate-free Hybrid Coating for Corrosion Protection of Electrogalvanized Steel Sheets

  • Jo, Du-Hwan;Kwon, Moonjae;Kim, Jong-Sang
    • Corrosion Science and Technology
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    • v.11 no.1
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    • pp.15-19
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    • 2012
  • Both electrogalvanized and hot-dip galvanized steel sheets have been finally produced via organic-inorganic surface coating process on the zinc surface to enhance corrosion resistance and afford additional functional properties. Recently, POSCO has been developed a variety of chromate-free coated steels that are widely used in household, construction and automotive applications. New organic-inorganic hybrid coating solutions as chromate alternatives are comprised of surface modified silicate with silane coupling agent and inorganic corrosion inhibitors as an aqueous formulation. In this paper we have prepared new type of hybrid coatings and evaluated quality performances such as corrosion resistance, spot weldability, thermal tolerance, and paint adhesion property etc. The electrogalvanized steels with these coating solutions exhibit good anti-corrosion property compared to those of chromate coated steels. Detailed components composition of coating solutions and experimental results suggest that strong binding between organic-inorganic hybrid coating layer and zinc surface plays a key role in the advanced quality performances.

ACCELERATED HYBRID ALGORITHMS FOR NONEXPANSIVE MAPPINGS IN HILBERT SPACES

  • Baiya, Suparat;Ungchittrakool, Kasamsuk
    • Nonlinear Functional Analysis and Applications
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    • v.27 no.3
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    • pp.553-568
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    • 2022
  • In this paper, we introduce and study two different iterative hybrid projection algorithms for solving a fixed point problem of nonexpansive mappings. The first algorithm is generated by the combination of the inertial method and the hybrid projection method. On the other hand, the second algorithm is constructed by the convex combination of three updated vectors and the hybrid projection method. The strong convergence of the two proposed algorithms are proved under very mild assumptions on the scalar control. For illustrating the advantages of these two newly invented algorithms, we created some numerical results to compare various numerical performances of our algorithms with the algorithm proposed by Dong and Lu [11].

Electrical Properties of Organic/Inorganic Hybrid Composites for Insulation Materials

  • Kim, Sang-Cheol;Ok, Jeong-Bin;Aho, Myeong-Jin;Park, Do-Hyun;Lee, Gun-Joo
    • Transactions on Electrical and Electronic Materials
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    • v.3 no.1
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    • pp.9-13
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    • 2002
  • In this work, the surface of inorganic fillers were modified with some functional groups such as stearic acid, aliphatic long chain, vinylsilane and aminosilane to control the interaction between inorganic fillers and polymer matrix. Ethylene-vinyl acetate copolymers (EVA) with various amount of vinyl-acetate and copolyether-ester elastomer were used as polymer matrix. The addition of inorganic fillers increases flame retardancy, but results in steep drop of electrical and mechanical properties, which may be caused by the defects in the interface between organic/inorganic hybrid composites. The hybrid composites are found to show better mechanical properties and higher volume resistivities as inorganic fillers are well dispersed and have good adhesion with polymer matrix. Also, the most effective type of functional group coated on fillers depends on the chemical structure of polymer.