• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1388-1390
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• 2013

Macroporous $SnO_2$ foam was successfully synthesized via a simple soft-chemical route by hybridization between alkylamine and tin(IV) oxide. According to X-ray diffraction (XRD) analysis, the as-prepared $SnO_2$ foam had a highly ordered lamella structure along the crystallographic c-axis, which transformed to a rutile phase after thermal treatment at $300^{\circ}C$. X-ray absorption spectroscopy (XAS) at the Sn K-edge revealed that $SnO_2$ particles in the hybrid material maintained their nanosized structure after hybridization with alkylamine. Scanning electron microscope (SEM) images clearly showed that the as-prepared $SnO_2$ foam had a macroporous structure. This synthetic route can be extended to the development of open frameworks with good electrochemical properties in battery applications.

• Journal of Powder Materials
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• v.11 no.3
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• pp.242-246
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• 2004

FePt nanoparticles for high-density magnetic recording media were synthesized by the simultaneous chemical reduction of Fe(acac) $_2$ and Pt(acac) $_2$ with 1,2-hexadecanediol as the reducing reagent. TEM images showed that the shape of as-synthesized FePt nanoparticle was spherical and average particle size was 3 nm. Also, SAD pattern showed that crystal structure was disordered FCC (face centered cubic). These FCC structured nanoparticles were transformed FCT (face centered tetragonal) structure by annealing at 55$0^{\circ}C$ for 30 min in Ar atmosphere. XRD analysis revealed that as-synthesized FePt nanoparticles were transformed from disordered FCC to ordered FCT. Finally, the coercivity of 2 kOe for FePt nanoparticles with FCT structure was obtained by VSM measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.49-53
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• 1996

Crystal structures of N $a_{x}$W $O_3$(0.5$\leq$x$\leq$1.0) were investigated. Transmission electron microscopy (TEM) studies indicate that there is an ordering of sodium ions when x=0.75. The direction of ordering is [110] and the wavelength of ordering is twice of the interplanar distance of (110) plane. It has been confirmed that a superlattice containing eight N $a_{0.75}$W $O_3$is the unit cell of ordered structure. In this unit cell, Na sites at (100) and ($\frac{1}{2}$$\frac{1}{2}$$\frac{1}{2}$) are vacant. The ordered phase was preserved after the annealing at $600^{\circ}C$ in the air. In reduced N $a_{x}$W $O_3$with x=0.5 and 1.0, extra phases were found to coexist with the partially ordered perovskite phase. After annealing at $600^{\circ}C$, theses phases were transformed into the phases found in calcined specimens.ens.s.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.901-904
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• 2010

Decylthiocyanate (DTC) self-assembled monolayers (SAMs) on Au(111) were prepared by solution and vapor phase deposition methods at $50^{\circ}C$ for 24 h. The formation and surface structure of DTC SAMs were examined using scanning tunneling microscopy (STM). STM imaging revealed that DTC SAMs formed in 1 mM ethanol solution at $50^{\circ}C$ were composed of small ordered domains with lateral dimensions of a few nanometers and disordered phases, whereas DTC SAMs formed in the vapor phase at $50^{\circ}C$ contained two ordered phases: a closely packed c($4{\times}2$) superlattice and a striped phase with an interstripe spacing of 2.6 - 2.8 nm. It was also found that the ordered domain and vacancy island formation for DTC SAMs on Au(111) differs significantly from that of decanethiol SAMs, suggesting that adsorption mechanism is different from each other. From this study, it was confirmed that DTC SAMs with a high degree of structural order can be obtained by vapor phase deposition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.1
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• pp.36-41
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• 2002

Abstract The stoichiometric and double-ordered perovskite $Sr_2FeMoO_6$ (SFMO) polycrystalline ceramics were fabricated by sintering at above $900^{\circ}C$ in $H_2$(5%)/Ar reductive ambient. SMO polycrystals showed good ferromagnetic properties andmagnetrotesistqnce ratios of about 15 % at 8K and 3 % at room temperature. Amorphous SFMO thin films were deposited on $LaA1O_3$ and $SrTiO_3$ single crystal substrates using rf sputtering method with the SFMO polycrystalline ceramic target. Double-ordered perovskite polycrystalline SFMO thin films were fabricated by solid state crystallization by annealing the deposited amorphous films at above $680^{\circ}C$ in $H_2$(5%)/Ar reductive ambient. SFMO thin films exhibited ferromagnetic behavior. Their magnetroresistance ratios, however, were only 0.3~0.5% at 8K and disappeared with increasing the measuring temperature. This was attributed to the absence of magnetic spin tunneling between grains due to the porous structure and non-stoichiometric composition of the deposited films.

• Journal of Korean Vacuum Science & Technology
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• v.2 no.2
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• pp.63-77
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• 1998

The oxidation of NiAl(110) was investigated in the temperature regime between 300K and 1300 K using LEED (low energy electron diffraction), TPD (temperature programmed desorption) and HREELS (high resolution electron energy loss spectroscopy). The adsorption of N2O and O2 up to reconstructions. Stepwise annealing of the oxygen-saturated sample from 600 K to 1300K in UHV (ultra-high vacuum,) results in firstly the onset of randomly oriented then finally fairly well-ordered. 5 ${\AA}$ Al2O3 film with quasi-hexagonal periodicity. Ordered thicker oxide films of 18-30 ${\AA}$ seem to be grown on this interfacial oxide layer by direct oxidation of sample at elevated temperature between 1150 and 1300 K because of the LEED pattern consisting of new broad hexagonal spots and the previous 5 ${\AA}$ spots. Although the periodicity of surface oxygen arrays shows no significant change from an hexagonal close-packing, the O-O distance changes from ∼3.0 ${\AA}$ film to ∼2.9 ${\AA}$ for thicker oxides. with the appearance of Auger parameter, for the 5${\AA}$ film can be described better as an interfacial oxide layer. The observation of three symmetric phonon peaks can be also a supporting evidence for this phase assignment since thicker oxide films on the Same Ni2Al3(110) show somewhat different phonon structure much closer to that of the ${\gamma}$-Al2O3. The adsorption/desorption of methanol further proves the preparation of less-defective and/or oxygen-terminated Al2O3 films showing ordered phase transitions with the change of oxide thickness between 5 ${\AA}$ to 30 ${\AA}$.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.579-584
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• 1998

In this work, we present a method to deal with the interval valued decision making systems. First, we propose a new type of equality measure based on the Ordered Weighted Averaging (OWA) operator. The proposed equality measure has a structure to render the extreme values of the measure by choosing a suitable weighting vector of the OWA operator. From this property, we derive a bidirectional fuzzy inference network which can be applied for the decisionmaking systems requiring the inverval valued decisions.

• Macromolecular Research
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• v.17 no.4
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• pp.280-283
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• 2009

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.11a
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• pp.309-314
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• 2006

The linear Consecutive-k-out-of-n:F system consists of n component ordered linearly and fail if and only if at least k consecutive components fail. We assume that the components are independent and identical exponentially distributed. This paper develops a model to calculate the expected cost per unit time of a linear consecutive-k-out-of-n:F system. The optimization problem we consider regards the choice of the system structure parameter k to minimized the expected cost per unit time.

• Journal of the Korean Data and Information Science Society
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• v.17 no.1
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• pp.187-193
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• 2006

This paper shows how to use continuation-ratio logits for the analysis of structured polytomous data. Here, response categories are considered to have a nested binary structure. Thus, conditionally nested binary random variables can be defined in each step. Two types of factors are considered as independent variables affecting response probabilities. For the purpose of analyzing categorical data with binary nested strutures a continuation-ratio mixed model is suggested. Estimation procedure for the unknown parameters in a suggested model is also discussed in detail by an example.