• Korean Journal of Crystallography
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• v.6 no.2
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• pp.80-87
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• 1995

The structure of Tetrapropionyloxycalix[4]arene(C40H40O8) has been studied by X-ray diffraction method. The crystal is monoclinic a=13.921(3), b=13.552(2), c=19.840(5)Å, β=110.38(2)°, Z=4 T=297K, Dc=1.23gcm-3, F(000)=1376, Systematic absences : hkl none, h0l : h+l=2n, 0k0: k=2n define space group P21/n. The structure was solved by direct method and refined by full-matrix least-squares methods to final R of 0.06 for 2514 observed reflections. The macrocycle exists in partial cone conformation. Three propionyl groups direct toward the exterior of the macrocycle cavity.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1209-1219
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• 2007

It is difficult to run 3D graphics based application on the embedded system with hardware constraints. Therefore, such a system must have a systematic infrastructure which can process various operations with respect to 3D graphics through any graphic acceleration module. In this paper, we present a method to implement 3D graphics acceleration device driver on Tiny X platform which provide an open source graphics windowing environment. The proposed method is to initialize the driver step by step so that the direct rendering infrastructure can use it properly. Moreover, we evaluated overall 3D graphics performance of an implemented driver through a simple but effective benchmark program.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.368-368
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• 2012

We report solution-processed, high-performance single-crystal organic nanowire transistors fabricated from a novel indolocarbazole (IC) derivative. The direct printing process was utilized to generate single-crystal organic nanowire arrays enabling the simultaneous synthesis, alignment and patterning of nanowires using molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. These new molecules are particularly suitable for p-channel organic field-effect transistors (OFETs) because of the high level of crystallinity usually found in IC derivatives. Selected area diffraction (SAED) and X-ray diffraction (XRD) experiments on these solution-processed nanowires showed high crystallinity. Transistors fabricated with these nanowires gave a hole mobility as high as 1.0 cm2V-1s-1 with nanowire arrays with the direct printing process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.943-946
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• 2007

In-plane piezoelectric charge constant of Electro-Active paper (EAPap) was investigated based on direct and converse piezoelectric effects. EAPap samples were made with cellulose film with very thin gold electrode coated on both sides of the film. To characterize direct piezoelectricity of EAPap, induced charge was measured when mechanical stress was applied to EAPap. In-plane piezoelectric charge constant was extracted from the relation between induced charge and applied in-plane normal stress. To investigate converse piezoelectricity, induced in-plane strain was measured when electric field was applied to EAPap. Piezoelectric charge constant was also extracted from the relation of induced in-plane strain and applied electric field. Piezoelectric charge constants obtained from direct and converse piezoelectricity are 31 pC/N and 178 x 10-12m/V for 45 degree sample, respectively. Measured piezoelectric charge constants of EAPap provide promising potential as a piezoelectric material.

• Journal of the Korean Ceramic Society
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• v.28 no.11
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• pp.843-850
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• 1991

There is a growing demend for absorptive electromagentic shielding materials for wide band frequency application. In this study, the absorber which consists of a rubber plus Ni-Zn ferrite which have been prepared by direct-wet method. A rubber ferrite composite for electromagnetic shielding, it is most importan facter the homogeneous ultra fine size and high dispersitive ferrite powder. Direct-wet method and solid-solid reaction method for preparing of ultra fine ferrite powder was used. It has been experimentally verified that the powder which prepared by direct-wet method was very fine and almost same size spherical powder, the composite ferrite have excellent electromagnetic wave absorption in X-band.

• Applied Microscopy
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• v.44 no.4
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• pp.133-137
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• 2014

We suggest a facile transmission electron microscopy (TEM) specimen preparation method for the direct (polymer-free) transfer of layer-area graphene from Cu substrates to a TEM grid. The standard (polymer-based) method and direct transfer method were by TEM, high-resolution TEM, and energy dispersive X-ray spectroscopy (EDS). The folds and crystalline particles were formed in a graphene specimen by the standard method, while the graphene specimen by the direct method with a new etchant solution exhibited clean and full coverage of the graphene surface, which reduced several wet chemical steps and accompanying mechanical stresses and avoided formation of the oxide metal.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.125-129
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• 2021

We investigated the electronic property and atomic structure for chalcopyrite (CH) Al_xGa_1-xAs semiconductor by using first-principles FPLMTO method. The CH-Al_xGa_1-xAs exhibits a p-type semiconductor with a direct band-gap. For low Al concentration unoccupied hole-carriers are induced, but for high Al concentration it is formed a localized bonding or anti-bonding state below Fermi level. The hybridization of Al(3s)-Ga(4s, or 4p) is larger than that of Al(3s)-As(4s, or 4p). And the Al film on As-terminated surface, Al/AsGa(001), is more energetically favorable one than that on Ga-terminated (001) surface. Consequently, the band-gap of CH-Al_xGa_1-xAs system increases exponentially with increasing Al concentration. The change of lattice parameter is shown two different configurations with increasing Al concentration. The calculated lattice parameters for CH-Al_xGa_1-xAs system are compared to the experimental ones of zinc-blend GaAs and AlAs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.35-38
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• 2002

In this paper, for digital x-ray conversion receptor development studied by hybrid technology of based on CdZnTe. For this study, First searched fabricate method of CdZnTe x-ray receptor. Second, search the phosphor material & fabricate method for scintillator layer. Fabricated sample is analyzed with physical & electric measurement. This result is showed good SNR ratio hybrid thechnology with direct method & indirect method. In this paper offer the method can reduce the dark-current in the hybrid X-ray detector.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.55.1-55.1
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• 2017

A number of recent studies have claimed that the double red clump observed in the Milky Way bulge is a consequence of an X-shaped structure. In particular, Ness & Lang (2016) report a direct detection of a faint X-shaped structure in the bulge from the residual map of the Wide-Field Infrared Survey Explorer (WISE) image. Here we show, however, that their result is seriously affected by a bulge model subtracted from the original image. When a boxy bulge model is subtracted, instead of a simple exponential bulge model as has been done by Ness & Lang, we find that most of the X-shaped structure in the residuals disappears. Furthermore, even if real, the stellar density in the claimed X-shaped structure appears to be too low to be observed as a strong double red clump at $l=0^{\circ}$

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.163.2-163.2
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• 2014

We report catalytic decomposition of few-layer graphene on an $Au/SiO_x/Si$ surface wherein oxygen is supplied by dissociation of the native $SiO_x$ layer at a relatively low temperature of $400^{\circ}C$. The detailed chemical evolution of the graphene covered $SiO_x/Si$ surface with and without gold during the catalytic process is investigated using a spatially resolved photoelectron emission method. The oxygen atoms from the native $SiO_x$ layer activate the gold-mediated catalytic decomposition of the entire graphene layer, resulting in the formation of direct contact between the Au and the Si substrate. The notably low contact resistivity found in this system suggests that the catalytic depletion of a $SiO_x$ layer could realize a new way to micromanufacture high-quality electrical contact.