• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.396-396
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• 2013

The resistive random access memory (ReRAM) has several advantages to apply next generation non-volatile memory device, because of fast switching time, long retentions, and large memory windows. The high mobility of monolayered graphene showed several possibilities for scale down and electrical property enhancement of memory device. In this study, the monolayered graphene grown by chemical vapor deposition was transferred to $SiO_2$ (100 nm)/Si substrate and glass by using PMMA coating method. For formation of metal-oxide nanoparticles, we used a chemical reaction between metal films and polyamic acid layer. The 50-nm thick BPDA-PDA polyamic acid layer was coated on the graphene layer. Through soft baking at $125^{\circ}C$ or 30 min, solvent in polyimide layer was removed. Then, 5-nm-thick indium layer was deposited by using thermal evaporator at room temperature. And then, the second polyimide layer was coated on the indium thin film. After remove solvent and open bottom graphene layer, the samples were annealed at $400^{\circ}C$ or 1 hr by using furnace in $N_2$ ambient. The average diameter and density of nanoparticle were depending on annealing temperature and times. During annealing process, the metal and oxygen ions combined to create $In_2O_3$ nanoparticle in the polyimide layer. The electrical properties of $In_2O_3$ nanoparticle ReRAM such as current-voltage curve, operation speed and retention discussed for applictions of transparent and flexible hybrid ReRAM device.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.199-206
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• 2003

The charcoal-encapsulated methyl silica microcapsules were prepared by a O/W microemulsion sol-gel method, and the adsorption properties on aquatic humic acid were investigated. The capsules prepared were spherical, $100{\sim}1000{\mu}m$ in size. The size distribution was controllable by adjusting the size of charcoal powder, charcoal/methyl silica ratio, and agitating speed in O/W sol-gel process. Adsorption efficiency of charcoal for aquatic humic acid was decreased after encapsulation by methyl silica shell. The decreased adsorption efficiency can be dependent on the decrease of the BET surface area and pore volume after encapsulation. Diffusion properties of humic acid through the capsule shell also played an important role on adsorption efficiency. Therefore, the reasonable target pollutants for the capsules can be VOC or odor molecules which can overcome diffusion barrier through shell of capsules in air condition. Functionalization methods for the charcoal-encapsulated $CH_3(SiO)_n$ microcapsules by incorporation of $TiO_3$ as a phtocatalytic function and by incorporation of inorganic pigment as a color function were also investigated. $TiO_2$ coating properties were controllable by adjusting pH, temperature, and the concentration of $TiOSO_4$. In XRD measurement, the crystal form of the coated $TiO_2$ was anatase. For the colorization of the capsules, inorganic pigments were more efficient than organic dyes, and various color was introduced to the capsules using inorganic pigments.

• Clean Technology
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• v.14 no.1
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• pp.35-39
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• 2008

In this study, we successfully fabricated a super-hydrophobic polymer layer on the surface of slide glass using the solubility difference of a polymer at two different solvents. After dissolving polystyrene (PS) resins in tetrahydrofuran (THF) as a good solvent and then adding ethanol(EtOH) as a poor solvent, we were able to fabricate super-hydrophobic surface. We also investigated the effect of EtOH addition, coating methods, solution mixing time and speed, and other alcohols on the surface hydrophobicity. The water contact angle (WCA) of the fabricated surface revealed $WCA>150^{\circ}$ and the microporous surface structure composed of microparticles with the size less than $5\;{\mu}m$.

• Resources Recycling
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• v.19 no.1
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• pp.27-32
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• 2010

To improve electronic conductivity of cathodic active materials of lithium ion battery, carbonaceous materials is usually added. New mixing method of abrasive milling has been investigated in mixing of graphite and $LiCoO_2$ powders. It would be expected that uniform mixing of graphite reduces capacity fading of cathode of lithium battery. Abrasion milled $LiCoO_2$ composite showed the best electrochemical performance as a cathode material with 1 wt% of graphite content, 300 rpm of milling speed, and 10 min of milling time. The improvement of the electrochemical performances such as cycleability and charge/discharge capacity retention would be mainly attributed to increase of the electronic conductivity and/or prevention of the active materials by uniform dispersion and coating of graphite on $LiCoO_2$.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.35-40
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• 1993

A FET(field effect transistor) type lipid sensor was fabricated uy immobilizing lipase enzyme on the gate of pH-ISFET($SiO_{2}/Si_{3}N_{4}$). A water soluble polymer, polyvinyl alcohol(PVA) was modified with 1-methyl-4-(formyl-styryl) pyridinium methosulfate(SbQ) to give a photosensitive membrane(PVA-SbQ) in which lipase was immobilized. The optimum photolithographic conditions were ; spin coating speed $5,000{\sim}6,000$ rpm. UV exposure time $20{\sim}30$ seconds, developing time in water $30{\sim}40$ seconds, and vacuum drying time 45 min. at room temperature with the suspension containing PVA-SbQ aqueous solution(SbQ 1mol%, 10 wt %) $200{\mu}L$, bovine serum albumin (BSA) 7.5 mg, and lipase 10 mg. The lipid sensor showed good linear calibration curve in the range of $10{\sim}100$ mM triacetin as a lipid sample.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.274-281
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• 2018

Experimental studies of the hydrodynamic performance of the draft tube conical spout-fluid bed (DCSF) were conducted using pharmaceutical pellets. The experiments were carried out in a DCSF consisted of two sections: (a) a conical section with the cross section of $120mm{\times}250mm$ and the height of 270 mm, (b) a cylindrical section with the diameter of 250 mm and the height of 600 mm. The flow characteristics of solids were investigated with a high speed camera and a pezoresistive absolute pressure transducer simultaneously. These characteristics revealed different flow regimes in the DCSF: packed bed at low gas velocities, fluidized bed in draft tube at higher gas velocities until minimum spouting, and spouted bed. The stable spouting was identified by the presence of two dominant frequencies of the power spectrum density of pressure fluctuation signature: (i) the frequency band 6-9 Hz and (ii) the frequency band 12-15 Hz. The pressure drops across the draft tube as well as the annulus measured in order to better recognize the flow structure in the DCSF. It was observed that the pressure drop across the draft tube, the pressure drop across the annulus, and the minimum spouting velocity increase with the increase in the height of draft tube and distance of the entrainment zone, but with the decrease in the distributor hole pitch. Finally, this study provided novel insight into the hydrodynamic of DCSF, particularly minimum spouting and stable spouting in the DCSF which contains valuable information for process design and scale-up of spouted bed equipment.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.127-134
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• 2021

A hydrophobic emulsion consisting of PMHS and PVA was mixed into a cement mortar to observe changes in cement hydrate and microstructure, and to experimentally evaluate compressive strength and flexural strength. The hydrophobic emulsion was added with metakaolin and PVA fibers, and the stirring speed and sequence were adjusted to prepare a shell-concept hydrophobic emulsion. It was then mixed when mixing mortar to enhance filling of the internal pores and change of the hydrates. It was observed that the mortar mixed with a hydrophobic emulsion was filled with micropores and a coating film was formed on the surface of the hydrates by the emulsion. It was analyzed that the total pore area and porosity of the mortar mixed with the emulsion decreased from 30% to 60% compared to OPC, excluding the 50MK variable, which was extremely reduced and the median pore diameter decreased in some variables. It was also found that the compressive strength of the mortar mixed with emulsion 1% was increased up to 20%, but the strength of the mortar specimen mixed with 2% decreased to 50%.

• Journal of Environmental Science International
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• v.32 no.6
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• pp.403-417
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• 2023

In this study, we investigated the characteristics of Volatile Organic Compounds(VOCs) emission from painting and printing facilities in the Pyeongdong industrial complex in Gwangju. In addition, the objective was to understand the distribution characteristics of VOCs in the ambient air in industrial complexes affected by painting and printing facilities. The painting facility mainly emitted toluene, acetone, butyl acetate, 4-methyl-2-pentanone, ethyl acetate, 1-butanol, methyl ethyl ketone, m,p-xylene, o-xylene, 4-ethyltoluene, ethylbenzene, 3-ethyltoluene, and 1,2,4-trimethylbenzene. The main emission components in printing facilities were methyl ketone, ethyl acetate, acetone, 2-propanol, toluene, heptane, and butyl acetate. Ethyl acetate, toluene, 2-butanone, acetone, butyl acetate, 2-propanol, xylenes, and 4-methyl-2-pentanone were detected in the ambient air of the Pyeongdong industrial complex, consistent with the VOCs emitted by painting and printing facilities. The average concentration of seasonal TVOCs followed an order of winter > fall > spring > summer, whereas the concentrations of daytime and nighttime TVOCs were generally higher at night than those during the day, and the wind speed was greater during the day than it was at night. Based on a factor analysis of VOCs in the ambient air of Pyeongdong industrial complex, it is considered that organic solvents used in coating, printing, and electronics manufacturing facilities, as well as diesel vehicle emissions played a major role.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.255-262
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• 2011

This paper has relatively high technical standard and experimental skill. The fabrication of TCO film with high transparency, low resistance and low chromaticity require exact control of several competing factors. This paper has resolved these problems reasonably well, thus recommended for publication. Indium tin oxide(ITO) thin films were by D.C. magnetron roll-to-roll sputter system utilizing ITO and $SiO_2$ targets of ITO and $SiO_2$. In this experiment, the effect of D.C. power, winding speed, and oxygen flow rate on electrical and optical properties of ITO thin films were investigated from the view point of sheet resistance, transmittance, and chromaticity($b^*$). The deposition of $SiO_2$ was performed with RF power of 400W, Ar gas of 50 sccm and the deposition of ITO, DC power of 600W, Ar gas of 50 sccm, $O^2$ gas of 0.2 sccm, and winding speed of 0.56m/min. High quality ITO thin films without $SiO_2$ layer had chromaticity of 2.87, sheet resistivity of 400 ohm/square, and transmittance of 88% and $SiO_2$-doped ITO Thin film with chromaticity of 2.01, sheet resistivity of 709 ohm/square, and transmittance of more than 90% were obtained. As a result, $SiO_2$ was coated on PET before deposition of ITO, their chromaticity($b^*$) and transmittance were better than previous results of ITO films. These results show that coating of $SiO_2$ induced arising chromaticity($b^*$) and transmittance. If the thickness of $SiO_2$ is controlled, sheet resistance value of ITO film will be expected to be better for touch screen. A four point probe and spectrophotometer are used to investigate the properties of ITO thin films.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.877-882
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• 2014

The reduction of CO2 emission has been discussed in the Marine Environment Protection committee in the International Maritime Organization as the biggest causes of GHG for the purpose of indexing CO2 amounts released into the atmosphere from ships. Accordingly, various methods including the change in the hull design to improve energy efficiency, the coating development to reduce friction resistances, the additives development for improving thermal efficiency in an engine, the low-speed operation to reduce fuel consumptions, and etc. have been applied. The main engine of a ship is an electronic engine for improving the efficiency of the whole load area. However, marine generator engines still use mechanical drive engines in intake, exhaust, and fuel injection valve drive cams. In addition, most of marine generator engines in ships apply a part-load operation of less then 80% due to an overload protection system. Therefore, marine auxiliary diesel engine set at 100% load is necessary to readjust in order to efficient operation because of part-load operation. The objective of this study is to report the results of the part-load fuel consumption improvement by injection timing readjust to identifying the operational characteristics of a marine generator engine currently operated in a ship.