• Membrane Journal
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• v.23 no.2
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• pp.151-158
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• 2013

The effect of layered double hydroxides (LDH) on the gas separation properties of ethylene vinyl acetate copolymer was investigated. Mg-Al LDH/EVA nanocomposite membranes were prepared from solution intercalation using organically modified LDH (DS-LDH). Dodecyl sulfate (DS)-LDH was obtained by the intercalation of DS anion in the interlayer. The nanocomposite structure has been elucidated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). XRD pattern clearly shows that the DS-LDH layers are disorderly well dispersed in the EVA matrix. The maximum tensile strength and elongation of the LDH/EVA nanocomposite membrane were found with the LDH content 3 wt%. The thermal properties of nanocompostie membrane were enhanced by the incorporation of LDH in EVA matrix. Gas permeation of LDH/EVA nanocomposite membranes with LDH contents of 1, 3, 5 wt% was studied for $O_2$ and $CO_2$ single gases. The presence of 3 wt% LDH decreased $O_2$ permeability by up to 53% compared to the EVA membrane. In spite of barrier property of nanocomposite membrane, however, the gas permeability for $CO_2$ was increased due to its strong affinity with the residual OH groups on the LDH.

• Membrane Journal
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• v.11 no.4
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• pp.143-151
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• 2001

We have fabricated mixed-ionic conducting membranes, L $a_{0.6}$S $r_{0.4}$ $Co_{0.2}$F $e_{0.8}$ $O_{3-}$$\delta$/ and L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ by the solid state method. Ceramic membranes consisted of perovskite-type structures and exhibited high relative density, >95%. Especially, dense L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ layer was coated on the L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membranes by using screen printing technique in order to improve oxygen ion flux. We measured oxygen ion flux on uncoated L $a_{0.6}$S $r_{0.4}$ $Co_{0.2}$F $e_{0.8}$ $O_{3-}$$\delta$/, uncoated L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/, and coated L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membranes. The L $a_{0.6}$S $r_{0.4}$ $Co_{0.2}$F $e_{0.8}$ $O_{3-}$$\delta$/ membranes showed the highest flux, 0.26 mL/min.$\textrm{cm}^2$ at 90$0^{\circ}C$, after steady state had been reached. The oxygen flux of coated L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membranes showed higher value, 0.19 mL/min.$\textrm{cm}^2$ at 95$0^{\circ}C$. This flux was as much as 2 or 3 times higher than those of uncoated L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membranes. 3-$\delta$/ membranes.X> 3-$\delta$/ membranes.membranes.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.143-151
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• 2020

Recently, research on self-healing concrete has been actively conducted, and various methods have been attempted for use in the maintenance of structures. However, contrary to the technical development of self-healing concrete, the method for evaluating the performance is insufficient. Although surface observation and permeability experiments are widely used to observe the healing of cracks, microscopic observation of surface may be insufficient to assess the overall performance. Also, permeation experiments should consider the losses caused by the dissolution of self-healed product and viscosity of water. Although a gas diffusion experiment have been proposed to overcome the shortcomings of these two test methods, verification has not been made on specimens with actual healing. Therefore, in this study, gas diffusion experiments were performed on the mortar specimens that had healed, and the adequacy of self-healing evaluation by the gas diffusion experiment was verified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.51-58
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• 2018

In this paper, the organic material Poly(methyl methacrylate) PMMA is used with inorganic $Al_2O_3$ to fabricate organic-inorganic multilayer barrier thin films. The organic thin films are developed using a roll-to-roll electrohydrodynamic atomization system, whereas the inorganic are grown using a roll-to-roll low-temperature atmospheric pressure atomic layer deposition system. For the first time, these two technologies are used together to develop organic-inorganic multilayer barrier thin films in atmospheric condition. The films are grown under optimized parameters and classified into three classes based on the layer structures, when the total thickness of the barrier is maintained at ~ 160 nm. All classes of barriers show good morphological, optical and chemical properties. The $Al_2O_3$ films with a low average arithmetic roughness of 1.58 nm conceal the non-uniformity and irregularities in PMMA thin films with a roughness of 5.20 nm. All classes of barriers show a notably good optical transmission of ~ 85 %. The hybrid organic-inorganic barriers show water vapor and oxygen permeation in the range of ${\sim}3.2{\times}10^{-2}g/m^2/day$ and $0.015cc/m^2/day$ at $23^{\circ}C$ and 100% relative humidity. It has been confirmed that it can be mass-produced and used as a low-cost barrier thin film in various printing electronic devices.

• Membrane and Water Treatment
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• v.7 no.5
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• pp.417-431
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• 2016

Poly(vinylidene fluoride) (PVDF) powder was treated with aqueous sodium hydroxide to obtain partially defluorinated fluoropolymers with expected properties such as improving hydrophilicity and fouling resistance. Raman spectrum and FT-IR results confirmed the existence of conjugated carbon double bonds after alkaline treatment. As the concentration increased, the degree of defluorination increased. The morphology and structure of membranes were examined. The permeation performance was investigated. The results showed that membrane's hydrophilicity increased with increase of the percentage of alkaline treated PVDF powder. Moreover, in terms of the water contact angle, it decreased from $92^{\circ}$ to a minimum of $68^{\circ}$; while water up take increased from 128 to 138%. Fluxof pure water and the cleaning efficiency increased with the increase of alkaline treated PVDF powder. The fouling potential also decreased with the increase of the percentage of alkaline treated PVDF powder. The reason that makes blending PVDF show different characteristics because of partial defluorination, which led the formation of conjugated C = C bonds and the inclusion of oxygen functionalities. The polyene structure followed by hydroxide attack to yield hydroxyl and carbonyl groups. Therefore, the hydrophilicity of blending membrane was improved. The SEM and porosity measurements showed that no obvious variations of the pore dimensions and structures for blend membranes were observed. Mechanical tests suggest that the high content of the alkaline treated PVDF result in membranes with less tolerance of tensile stress and higher brittleness. TGA results exhibited that the blend of alkaline treated PVDF did not change membrane thermal stability.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.305-308
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• 2006

Advanced mobile communication devices require a bright, high information content display in a small, light-weight, low power consumption package. For portable applications flexible (or conformable) and rugged displays will be the future. In this paper we outline our progress towards developing such a low power consumption active-matrix flexible OLED $(FOLED^{TM})$ display. We demonstrate full color 100 ppi QVGA active matrix OLED displays on flexible stainless steel substrates. Our work in this area is focused on integrating three critical enabling technologies. The first technology component is based on UDC's high efficiency long-lived phosphorescent OLED $(PHOLED^{TM})$ device technology, which has now been commercially demonstrated as meeting the low power consumption performance requirements for mobile display applications. Secondly, is the development of flexible active-matrix backplanes, and for this our team are employing PARC's Excimer Laser Annealed (ELA) poly-Si TFTs formed on metal foil substrates as this approach represents an attractive alternative to fabricating poly-Si TFTs on plastic for the realization of first generation flexible active matrix OLED displays. Unlike most plastics, metal foil substrates can withstand a large thermal load and do not require a moisture and oxygen permeation barrier. Thirdly, the key to reliable operation is to ensure that the organic materials are fully encapsulated in a package designed for repetitive flexing, and in this device we employ a multilayer thin film Barix encapsulation technology in collaboration with Vitex systems. Drive electronics and mechanical packaging are provided by L3 Displays.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.95-95
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• 2014

An OLED(Organic Light-Emitting Diode) device based on the emissive electroluminescent layer a film of organic materials. OLED is used for many electronic devices such as TV, mobile phones, handheld games consoles. ULVAC's mass production systems are indispensable to the manufacturing of OLED device. ULVAC is a manufacturer and worldwide supplier of equipment and vacuum systems for the OLED, LCD, Semiconductor, Electronics, Optical device and related high technology industries. The SMD Series are single-substrate sputtering systems for deposition of films such as metal films and TCO (Transparent Conductive Oxide) films. ULVAC has delivered a large number of these systems not only Organic Evaporating systems but also LTPS CVD systems. The most important technology of thin-film encapsulation (TFE) is preventing moisture($H_2O$) and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass substrate, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This report provides a review of promising thin-film barrier technologies as well as the WVTR(Water Vapor Transmission Rate) properties. Multilayer thin-film deposition technology of organic and inorganic layer is very effective method for increasing barrier performance of OLED device. Gases and water in the organic evaporating system is having a strong influence as impurities to OLED device. CRYO pump is one of the very useful vacuum components to reduce above impurities. There for CRYO pump is faster than conventional TMP exhaust velocity of gases and water. So, we suggest new method to make a good vacuum condition which is CRYO Trap addition on OLED evaporator. Alignment accuracy is one of the key technologies to perform high resolution OLED device. In order to reduce vibration characteristic of CRYO pump, ULVAC has developed low vibration CRYO pumps to achieve high resolution alignment performance between Metal mask and substrate. This report also includes ULVAC's approach for these issues.

• Herbal Formula Science
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• v.17 no.2
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• pp.163-174
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• 2009

Reactive oxygen species(ROS) can induce hepatotoxicity and trigger apoptosis in the liver. In this study, we investigated the sulfated polysaccharide A-1 from Opuntia ficus-indica against alcoholic oxidative stress in human liver Hep G2 cell. An antioxidant substance A-1 obtained from the enzymatic extract of Opuntia ficus-indica fruit was purified by DEAE-cellulose ion exchange and sephadex G-100 gel permeation chromatography. The purification yield and molecular weight were 14.3% and 1.8 KDa, respectively. The A-1 predominately contained arabinose, galactose, rhamnose and also sulfate group. The structure of A-1 was investigated by periodate oxidation, FT-IR spectroscopy, $^1H$-NMR spectroscopy. The A-1 mainly composed of alternating unit of ${\rightarrow}4$)-$\alpha$-L- Rapp-2-$SO_3^-$-$\alpha$-L-Galp-($1{\rightarrow}$ and branched linkage of $\beta$-D-Arbp- ($5{\rightarrow}$. The antioxidative activity was measured using the SOD, CAT activity and GSH assay, respectively. The expression of Nrf2 protein was analyzed by western blotting. The viable cell count analyzed by autofluorescence. Oxidative stress induced by ethanol(1 M) were dramatically reduced by A-1 treatment. A-1 also prevented cell death induced by oxidative stress. It also increased expression Nrf2 protein level. We concluded that sulfated polysaccharide A-1 from Opuntia ficus-indica effectively protect Hep G2 liver cell from alcoholic oxidative stress.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.554-558
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• 2017

In order to achieve a hydrophobic surface of silica, we reacted silica nanoparticles with hexamethyldisilazane (HMDS) under various reaction conditions. Modification of the surface of silica with organic materials was confirmed by the thermogravity and elemental analysis. The modified silica displayed nearly the same morphology as to the pristine silica. The reaction of 20 g of HMDS with 1 g of silica in decalin at $200^{\circ}C$ for 6 hours was found to be the optimum reaction condition in terms of the dispersity in toluene and the surface roughness of composite films. Oxygen permeation studies of the composite film demonstrated that the modified silica enhanced a gas barrier performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.56-57
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• 2006

In this paper, the inorganic multi-layer thin film encapsulation was newly adopted to protect the organic layer from moisture and oxygen. Using the electron beam, Sputter, inorganic multi-layer thin-film encapsulation was deposited onto the Ethylene Terephthalate(PET) and their interface properties between inorganic and organic layer were investigated. In this investigation, the SiON SiO2 and parylene layer showed the most suitable properties. Under these conditions, the WVTR for PET can be reduced from a level of $0.57\;g/m^2/day$ (bare subtrate) to 1*10-5 g/$m^2$/day after application of a SiON and SiO2 layer. These results indicates that the PET/SiO2/SiON/Parylene barrier coatings have high potential for flexible organic light-emitting diode(OLED) applications.