• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2277-2280
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• 2008

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1405-1407
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• 2009

We prepared polystyrene-b-poly(2-vinyl pyridine) (PSb-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer have 57 kg/mol-b-57 kg/mol. The result of UV-visible absorption spectra supported that effect of poly(ethylene oxide) on the band gap tuning of PS-P2VP photonic gel like salt effect.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.187-192
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• 2006

The preparation and characterization of new polymer composite membranes containing polyphenylene oxide (PPO) thin films with hetropoly acid (HPA) are presented. PPO thin films with phosphotungstic acid (PWA) or phosphomolybdic acid (PMA) have been prepared by using the solvent mixture. The PWA and PPO can be blended using the solvent mixture, because PPO and PWA are not soluble in the same solvent. In this study, methanol was used as a solvent dissolving PWA and chloroform was used as a solvent dissolving PPO. PPO-PWA solutions were cast onto a glass plate with uniform thickness. The composite membranes were prepared by casting Nafion mixture on porous PPO-PWA films. The morphology and structure of these PPO-PWA films were observed with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The composite membranes were characterized by measuring their ion conductivity and methanol permeability. The performance was evaluated with composite membranes as electrolytes in fuel cell conditions. The methanol cross-over of composite membranes containing PPO-PWA barrier films in the DMFC reduced by 66％.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1659-1663
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• 2003

$Al_2O_3$ thin films were grown on H-terminated Si(001) substrates using dimethylaluminum isopropoxide [DMAl: $(CH_3)_2AlOCH(CH_3)_2$], as a new Al precursor, and water by atomic layer deposition (ALD). The selflimiting ALD process by alternate surface reactions of DMAI and $H_2O$ was confirmed from measured thicknesses of the aluminum oxide films as functions of the DMAI pulse time and the number of DMAI-$H_2O$ cycles. Under optimal reaction conditions, a growth rate of ~1.06 ${\AA}$ per ALD cycle was achieved at the substrate temperature of $150\;^{\circ}C$. From a mass spectrometric study of the DMAI-$D_2O$ ALD process, it was determined that the overall binary reaction for the deposition of $Al_2O_3\;[2\;(CH_3)_2AlOCH(CH_3)_2\;+\;3\;H_2O\;{\rightarrow}\;Al_2O_3\;+\;4\;CH_4\;+\;2\;HOCH(CH_3)_2]$can be separated into the following two half-reactions: where the asterisks designate the surface species. Growth of stoichiometric $Al_2O_3$ thin films with carbon incorporation less than 1.5 atomic % was confirmed by depth profiling Auger electron spectroscopy. Atomic force microscopy images show atomically flat and uniform surfaces. X-ray photoelectron spectroscopy and cross-sectional high resolution transmission electron microscopy of an $Al_2O_3$ film indicate that there is no distinguishable interfacial Si oxide layer except that a very thin layer of aluminum silicate may have been formed between the $Al_2O_3$ film and the Si substrate. C-V measurements of an $Al_2O_3$ film showed capacitance values comparable to previously reported values.

• Journal of Adhesion and Interface
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• v.19 no.3
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• pp.113-117
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• 2018

Boron carbide is lower in hardness than diamond or boron nitride but has a hardness of more than 30 GPa and is used for manufacturing tank armors and ammo shells due to its high hardness. It is also used as a neutron absorber due to its ability to absorb neutrons, which is increasing its use in nuclear power projects. Neutrons have no interaction with electrons and are known to pass through the material without interactions. Along with boron carbide, the atoms with high interaction with neutrons are hydrogen, and high hydrogen concentration polyesters and epoxy polymers including boron are used as materials for manufacturing products for nuclear power generation waste. In this paper, the surface of boron carbide is treated with iron oxide and tungsten to improve interaction between modified boron carbide and epoxy polymer. XRD and XPS were used to confirm that iron oxide and tungsten are well attached on the surface of boron carbide, respectively. The mechanical strength of the surface treated boron carbide was measured by a universal testing machine (UTM) and the dynamic characteristics of the cured product were observed by using a dynamic analyzer (DMA).

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3213-3218
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• 2014

A metal organic framework-supported Nickel nanoparticle (Ni-MOF-5) was successfully synthesized using a simple impregnation method. The obtained solid acid catalyst was characterized by Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption and thermogravimetric analysis (TGA). The catalyst was highly crystalline with good thermodynamic stability (up to $400^{\circ}C$) and high surface area ($699m^2g^{-1}$). The catalyst was studied for the oxidation of ethyl benzene, and the results were monitored via gas chromatography (GC) and found that the Ni-MOF-5 catalyst was highly effective for ethyl benzene oxidation. The conversion of ethyl benzene and the selectivity for acetophenone were 55.3% and 90.2%, respectively.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.783-784
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• 2011

• Korean Journal of Materials Research
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• v.24 no.12
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• pp.682-688
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• 2014

Physical and chemical changes in a polished wafer and in $2.5{\mu}m$ & $4{\mu}m$ epitaxially grown Si layer wafers (Epilayer wafer) after surface treatment were investigated. We characterized the influence of surface treatment on wafer properties such as surface roughness and the chemical composition and bonds. After each surface treatment, the physical change of the wafer surface was evaluated by atomic force microscopy to confirm the surface morphology and roughness. In addition, chemical changes in the wafer surface were studied by X-ray photoemission spectroscopy measurement. Changes in the chemical composition were confirmed before and after the surface treatment. By combined analysis of the physical and chemical changes, we found that diluted hydrofluoric acid treatment is more effective than buffered oxide etching for $SiO_2$ removal in both polished and Epi-Layer wafers; however, the etch rate and the surface roughness in the given treatment are different among the polished $2.5{\mu}m$ and $4{\mu}m$ Epi-layer wafers in spite of the identical bulk structural properties of these wafers. This study therefore suggests that independent surface treatment optimization is required for each wafer type, $2.5{\mu}m$ and $4{\mu}m$, due to the meaningful differences in the initial surface chemical and physical properties.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1565-1570
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• 2020

Photons with the energy of 60 keV are regularly used for some kinds of bone density examination devices, like the single photon absorptiometry (SPA). This article reports a flexible and lightweight rare earth/polymer composite for enhancing shielding efficiency against photon radiation with the energy of 60 keV. Lead oxide (PbO) and several rare earth element oxides (La₂O₃, Ce₂O₃, Nd₂O₃) were dispersed into natural rubber (NR) and the photon radiation shielding performance of the composites were assessed using monte carlo simulation method. For 60 keV photons, the shielding efficiency of rare earthbased composites were found to be much higher than that of the traditional lead-based composite, which has bad absorbing ability for photons with energies between 40 keV and 88 keV. In comparison with the lead oxide based composite, Nd₂O₃-NR composite with the same protection standard (the lead equivalent is 0.25 mmPb, 0.35 mmPb and 0.5 mmPb, respectively), can reduce the thickness by 35.29%, 37.5% and 38.24%, and reduce the weight by 38.91%, 40.99% and 41.69%, respectively. Thus, a flexible, lightweight and lead-free rare earth/NR composite could be designed, offering efficient photon radiation protection for the users of the single photon absorptiometry (SPA) with certain energy of 60 keV.