• 한국세라믹학회지
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• 제54권1호
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• pp.38-42
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• 2017

Vanadium nitride (VN) coatings were deposited using inductively coupled plasma (ICP) assisted sputtering at different ICP powers. Microstructural, crystallographic and mechanical characterizations were performed by FE-SEM, AFM, XRD and nanoindentation. The results show that ICP has significant effects on coating's microstructure, structural and mechanical properties of VN coatings. With an increase in ICP power, coating microstructure evolved from a porous columnar structure to a highly dense one. Single- phase cubic (FCC) VN coatings with different preferential orientations and residual stresses were obtained as a function of ICP power. Average crystal grain sizes of single phase cubic (FCC) VN coatings were decreased from 10.1 nm to 4.0 nm with an increase in ICP power. The maximum hardness of 28.2 GPa was obtained for the coatings deposited at ICP power of 200 W. The smoothest surface morphology with Ra roughness of 1.7 nm was obtained in the VN coating sputtered at ICP power of 200 W.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.806-808
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• 2006

In order to understand the origin of liquid crystal orientation on a surface of photoaligning polymer polyvinyl-fluoro-cinnamate (PVCN-F), we used FTIR, AFM, UV/Vis and XPS techniques as well as we studied the rejuvenation of the photoalignment after repeated UV exposure with mutually perpendicular polarization. We found that both photodimerization of cinnamoil moieties and their trans-cis isomerisation contribute to the light-induced anchoring on PVCN-F surface, and trans-cis isomerisation is responsible for the rejuvenation of the photoalignment.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.475-477
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• 2003

Orientation of E7 liquid crystals (LCs) confined to 200 nm-diameter cylindrical cavities of Anodisc membranes are investigated by FTIR dichroism techniques. The cavity walls of the confining pores are chemically modified with different aliphatic acids ($C_nH_{2n+1}COOH$, n=5, 6, 7, 9). From the FTIR spectra of aliphatic acid treated alumina Anodsic membranes, we found the salt formation between -COOH group of aliphatic acid and Anodisc membrane. From the FTIR spectra of LC filled Anodisc membranes, we found abrupt alignment direction change of LC molecules between n=6 and 7 for 2% aliphatic acid treated Anodisc membranes, from parallel to perpendicular direction to the cavity walls. But 4% aliphatic acid treated Anodisc membranes, alignment direction of LC molecules changed between n=5 and n=6, from parallel to perpendicular direction. The same trend was observed for $^2H-NMR$ measurements.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.1112-1117
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• 2003

Polarized Fourier transform infrared (IR) absorption is used to probe molecular conformation in a ferroelectric liquid crystal (FLC) during the reorientation induced by the external field. Spectra of planar aligned cells of FLC W314 are measured as functions of IR polarizer orientation and electric field applied to the FLC. The time evolution of the dichroism of the absorbance due to biphenyl core and alkyl tail molecular vibration modes, is observed. Static IR dichroism experiments show a W314 dichroism structure in which the principal axis of dielectric tensor from molecular core vibration are tilted further from the smectic layer normal than those of the tail. This structure indicates the effective binding site in which the molecules are confined in the Sm-C phase has, on average, "zig-zag" shape and this zig-zag binding site structure is rigidly maintained while the molecular axis rotates about the layer normal during field-induced switching.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.463-465
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• 2002

In order to increase perpendicular magnetic anisotropy of magnetic layer and prepare magnetic recording layer with a good quality by epitaxial growth between magnetic layer and, we prepared Co$\_$77/Cr$\_$20/Ta$_3$/Si doublelayer for perpendicular magnetic recording media which was promoted as next generation recording media on slide glass substrate. The thickness of magnetic layer and Underlayer were varied from 20 to 100 nm and 5 to 100 m, respectively. The surface morphology and crystal structure of the CoCrTa/Si film were examined with XRD and AFM. Prepared thin films showed improvement of dispersion angle of c-axis orientation Δ$\theta$$\_$50/ caused by inserting amorphous Si underlayer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권11호
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• pp.496-500
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to significantly impact terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (RIE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi-Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7% efficiency of mono-crystalline silicon solar cell and 10.2% multi-crystalline silicon solar cell.

• 전기학회논문지
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• 제58권8호
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• pp.1566-1571
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• 2009

The discharge electrodes in ac PDP are coated with dielectric layer, and transparent MgO thin films are deposited on the dielectric layer. The main role of the MgO thin films in ac PDP is to protect the dielectric layer from sputtering by ion bombardment in the glow-discharge plasma. An additional important role of the MgO thin film is the high secondary electron emission coefficient which leads the low firing voltage and low cost of the PDP. In this paper, we investigated the relations of the crystal orientation about deposition thickness, deposition rate, temperature of substrate, and distance between the MgO tablet and the substrate. Additionally, we investigated the discharge characteristics of the AC PDP using nano-powder MgO tablet

• 대한기계학회논문집A
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• 제20권5호
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• pp.1516-1523
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• 1996

The present study is concerned with the development of anisotropy and deformation texture in polycrystals. The individual grain in an aggregate is assumed to experience the viscoplastic dedformation with crystallographic slip that unsure uniquenessof the active slip systems and shearing rate onthese systems. Two different methods for updating the grain orientation are examined. Texture development for some deformation modes such as plane strain compression, uniaxial tension and simple shear are found. Changes in anisotropic flow potential due to texture development during large deformation are also given. Anisotropic behavior of polycrystals with defferent textures are examined.

• 한국기계가공학회지
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• 제12권5호
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• pp.30-35
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• 2013

In order to increase cell efficiency in crystalline silicon solar cell, reduction of light reflection is one of the essential problem. Until now silicon wafer was textured by wet etching process which has random patterns along crystal orientation. In this study, high aspect ratio patterns are manufactured by nano imprint process and reflectance could be minimized under 1%. After that, screen printed solar cell was fabricated on the textured wafer and I-V characteristics was measured by solar simulator. Consequently cell efficiency of solar cell fabricated using the wafer textured by nano imprint process increased 1.15% than reference solar cell textured by wet etching. Internal quantum efficiency was increased in the range of IR wave length but decreased in the UV wavelength. In spite of improved result, optimization between nano imprinted pattern and solar cell process should be followed.

• Advances in materials Research
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• 제1권4호
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• pp.349-359
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• 2012

To reveal localized plastic deformation zones in a tough pitch copper, the etching characteristics of a copper sample have been examined. The etching was carried out on a sample surface using an etchant consisting of 25 ml nitric acid solution and 75 ml water. To clarify the plastic deformation zone, the sample deformed plastically was heated to between $250^{\circ}C$ and $300^{\circ}C$ before the etching process. This is due to a change of the microstructure and crystal orientation in the plastic deformation zone producing recrystallized small grains. In this case, the plastically deformed zone is severely etched, whereas the undeformed zone is only slightly etched. Identification of the details of the deformation zone from the etching is further discussed.