• Journal of Electrochemical Science and Technology
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• v.3 no.2
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• pp.68-71
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• 2012

The electrospinning technique is a revolutionary template-catalyst-free method that can generate 1D nanostructure with the tunability and the potential for the mass production. This approach received a great deal of attention due to its ability to give direct pathways for electrical current and has been utilized in various electronic applications. However, the delamination of inorganic electrospun film has prevented the intense utilization due to the thermal expansion/contraction during the calcination. In this study, we propose an electrical grounding method for transparent conducting oxide and electrospun nanowires to enhance the adhesion after the calcination. Then, we examined the potential of the technique on ZnO based dye-sensitized solar cells.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.313-318
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• 2007

Single-wall carbon nanotube field-effect transistors (SWCNT FETs) of top gate structure were fabricated in a conventional metal-oxide-semiconductor field effect transistor (MOSFET) with gate electrodes above the conduction channel separated from the channel by a thin $SiO_{2}$ layer. The carbon nanotubes (CNTs) directly grown using thin Fe film as catalyst by thermal chemical vapor deposition (CVD). These top gate devices exhibit good electrical characteristics, including steep subthreshold slope and high conductance at low gate voltages. Our experiments show that CNTFETs may be competitive with Si MOSFET for future nanoelectronic applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.252.1-252.1
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• 2013

Hexagonal boron nitride (h-BN) is a two dimensional material which has high band-gap, flatness and inert properties. This properties are used various applications such as dielectric for electronic device, protective coating and ultra violet emitter so on. 1) In this report, we were growing h-BN sheet directly on sapphire 2"wafer. Ammonia borane (H3BNH3) and nickel were deposited on sapphire wafer by evaporate method. We used nickel film as a sub catalyst to make h-BN sheet growth. 2) During annealing process, ammonia borane moved to sapphire surface through the nickel grain boundary. 3) Synthesized h-BN sheet was confirmed by raman spectroscopy (FWHM: ~30cm-1) and layered structure was defined by cross TEM (~10 layer). Also we controlled number of layer by using of different nickel and ammonia borane thickness. This nickel film supported h-BN growth method may propose fully and directly growing on sapphire. And using deposited ammonia borane and nickel films is scalable and controllable the thickness for h-BN layer number controlling.

• Current Photovoltaic Research
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• v.6 no.4
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• pp.91-93
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• 2018

Polythiophene-$TiO_2$ composite was synthesized with different molar ratios of thiophene and titaniumisopropoxide ($Ti(OPr)_4$) for flexible solar cell application as a flexible electrode or an active material. The $Ti(OPr)_4$ was stabilized by thiophene. The thiophene was polymerized by ferric chloride catalyst. The synthesized polythiophene exhibited strong UV-visible absorption in the range of the wavelength shorter than 500 nm. Field emission scanning electron microscope (FESEM) image of low concentration of $TiO_2$ film showed smooth surface. However, FESEM image of high concentration of $TiO_2$ film exhibited relatively rough surface. Polythiophene concentration dependent strong photoluminescence quenching of surfrhodamine-B was observed.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.512-518
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• 2019

To develop a membrane electrode assembly (MEA) with lower Pt loading and higher performance in proton exchange membrane fuel cells (PEMFCs), it is an important research issue to understand interfacial structure of Pt/C catalyst and ionomer and design the catalyst layer structure. In this study, we prepared short-side-chain Nafion-based ionomer dispersion using propylene glycol (PG) as a solvent instead of water which is commonly used as a solvent for commercially available ionomers. Cathode catalyst layers with different ionomer content from 20 to 35 wt% were prepared using the ionomer dispersion for the fabrication of four different MEAs, and their fuel cell performance was evaluated. As the ionomer content increased to 35 wt%, the performance of the prepared MEAs increased proportionally, unlike the commercially available water-based ionomer, which exhibited an optimum at about 25 wt%. Small size micelles and slow evaporation of PG in the ionomer dispersion were effective in proton transfer by inducing the formation of a uniformly structured catalyst layer, but the low oxygen permeability problem of the PG-based ionomer film should be resolved to improve the MEA performance.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.149-154
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• 1996

ZnO and Al-doped ZnO thin films were prepared by sol-gel dip-coating method and electrical and optical properties of films were investigated. Using the zinc acetate dihydrate and acetylaceton(AcAc) as a chelating agent stable ZnO sol was synthesized with HCl catalyst. Adding aluminium chloride to the ZnO sol Al-doped ZnO sol could be also synthesized. As Al contents increase the crystallinity of ZnO thin film was retarded by increased compressive stress in the film resulted from the difference of ionic radius between Zn2+ and Al3+ The thickness of ZnO and Al-doped ZnO thin film was in the range of 2100~2350$\AA$. The resistivity of ZnO thin films was measured by Van der Pauw method. ZnO and Al-doped ZnO thin films with annealing temperature and Al content had the resistivity of 0.78~1.65$\Omega$cm and ZnO and Al-doped ZnO thin film post-annealed at 40$0^{\circ}C$ in vacuum(5$\times$10-5 torr) showed the resistivity of 2.28$\times$10-2$\Omega$cm. And the trans-mittance of ZnO and Al-doped ZnO thin film is in the range of 91-97% in visible range.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.4
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• pp.266-270
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• 2016

We present a useful and practical manufacturing technique that enables the structural conversion of delicate as-grown nanostructures to more beneficial and robust thin-film frameworks through controlled mechanical rolling. Functional nanostructures such as carbon nanotubes grown through chemical vapor deposition in a vertically aligned and very loosely packed manner, and thus difficult to manipulate for subsequent uses, can be prepared in an array of thin blades by patterning the growth catalyst layer. They can then be toppled as dominos through precisely controlled mechanical rolling. The nanostructures formulated to horizontally aligned thin films are much more favorable for device applications typically based on thin-film configuration. The proposed technique may broaden the functionality and applicability of as-grown nanostructures by converting them into thin-film frameworks that are easier to handle and more durable and favorable for fabricating thin-film devices for electronics, sensors, and other applications.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.1-6
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• 2013

A simple thermal oxidation of Cu thin films deposited on planar substrates established a growth of vertically aligned copper oxide (CuO) nanorods. DC sputter-deposited Cu thin films with various thicknesses were oxidized in environments of various oxygen partial pressures to control the kinetics of oxidation. This is a method to synthesize vertically aligned CuO nanorods in a relatively shorter time and at a lower cost than those of other methods such as the popular hydrothermal synthesis. Also, this is a method that does not require a catalyst to synthesize CuO nanorods. The grown CuO nanorods had diameters of ~100 nm and lengths of $1{\sim}25{\mu}m$. We examined the morphology of the synthesized CuO nanorods as a function of the thickness of the Cu films, the gas environment, the oxidation time, the oxidation temperature, the oxygen gas flow rate, etc. The parameters all influence the kinetics of the oxidation, and consequently, the volume expansion in the films. Patterned growth was also carried out to confirm the hypothesis of the CuO nanorod protrusion and growth mechanism. It was found that the compressive stress built up in the Cu film while oxygen molecules incorporated into the film drove CuO nanorods out of the film.

• The Korean Journal of Ceramics
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• v.5 no.2
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• pp.125-130
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• 1999

After $SnO_2$ fine powder by precipitation method, Ca as crystallization inhibitor and Pd as catalyst were added to $SnO_2$ raw material by various methods. Thick film device was fabricated on the alumina substrate by mixing ethylene glycol and such mixed powders. The sensing characteristics of the device for methane gas were investigated. The most excellent gas sensing property was shown by the thick film device fabricated by Method 3 in which Ca and Pd doped $SnO_2$ powder is prepared by mixing $SnO_2$ powder, 0.1 wt% Ca acetate and 1 wt% $PdCl_2$ in deionized water and by calcining the mixture, after $Sn(OH)_4$ is dried at $110^{\circ}C$ for 36h. The sensitivity of the sensor fabricated with $SnO_2$-0.1 wt%Ca acetate-1wt%$PdCl_2$ powder heat-treated at $700^{\circ}C$ for 1h was about 86% for 5,000 ppm methane in air at $350^{\circ}C$ of the operating temperature. Response time and recovery were also excellent.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.481-489
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• 2004

Poly(triazine bissulfide)s were synthesized from 6-dibutylamino-1,3,5-triazine-2,4-dithiol with bis(4-chloro-3-nitrophenyl)sulfone in the presence of the phase transfer catalyst, and from m-dibromide xylene and p-dibromide xylene with 6-dibutylamino-1,3,5-triazine-2,4-dithiol in the presence of cetyltrimethyl ammonium bromide at $70^{\circ}C$ for 24h. We could acquire the good results about solubility, thermal property, and molecular weight to make cast film. These results are important as base for the synthesis of functionalization polymer material being optical plastic material. The maximum algebra viscosity was 0.57~1.40dl/g at the temperature more than $50{\sim}60^{\circ}C$.