• Clean Technology
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• v.24 no.1
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• pp.50-54
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• 2018

In this work, N-methyl-2-pyrrolidone (NMP) was added into diethylenetriamine (DETA) aqueous solution for high $CO_2$ loading via phase splitting of absorbents during $CO_2$ absorption. Immiscible two phases were formed in the range of more than 30 wt% of NMP in 2 M DETA + NMP + water absorbents because of low solubility of DETA-carbamate in NMP solution. As the composition of NMP in the absorbents increased, the difference of $CO_2$ loading between each phase increased and the volume of bottom phase decreased. In $CO_2$ absorption in packed column by 2 M DETA + NMP + water absorbents, the absorption rate decreased in the range of more than 40 wt% of NMP. It is due to the increasing of mass transfer resistance in liquid film of absorbents at the high concentration of NMP. DETA + NMP + water absorbent is expected as the promising one for reducing the regeneration energy of absorbents according to volume reduction of $CO_2-rich$ phase.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.6
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• pp.699-713
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• 2003

Statement of problem. Titanium is the most important material for biomedical and dental implants because of their high corrosion resistance and good biocompatibility. These beneficial properties are due to a protective passive oxide film that spontaneously forms on the surface. Purpose. The purpose of this study was to evaluate the responses of osteoblast-like cells on different surface treatments on Ti discs. Material and Methods. Group 1 represented the machined surface with no treatment. Group 2 surfaces were sandblasted with $50{\mu}m\;Al_2O_3$ under $5kgf/cm^2$ of pressure. Groups 3 and 4 were sandblasted under the same conditions. The samples were treated on a titanium oxide surface with reactive sputter depositioning and thermal oxidation at $600^{\circ}C$ (Group 3) and $800^{\circ}C$ (Group 4) for one hour in an oxygen environment. The chemical composition and microtopography were analyzed by XRD, XPS, SEM and optical interferometer. The stability of $TiO_2$ layer was studied by petentiodynamic curve. To evaluate cell response, osteoblast extracted from femoral bone marrow of young adult rat were cultured for cell attachment, proliferation and morphology on each titanium discs. Results and Conclusion. The results were as follows : 1. Surface roughness values were, from the lowest to the highest, machined group, $800^{\circ}C$ thermal oxidation group, $600^{\circ}C$ thermal oxidation group and blasted group. The Ra value of blasted group was significantly higher than that of $800^{\circ}C$ thermal oxidation group (P=0.003), which was not different from that of $600^{\circ}C$ thermal oxidation group (P<0.05). 2. The degree of cell attachment was highest in the $600^{\circ}C$ thermal oxidation group after four and eight hours (P<0.05), but after 24 hours, there was no difference among the groups (P>0.05). 3. The level of cell proliferation showed no difference among the groups after one day, three days, and seven days (P>0.05). 4. The morphology and arrangement of the cells varied with surface roughness of the discs.

• Polymer(Korea)
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• v.36 no.4
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• pp.486-493
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• 2012

Photocurable sulfonated polyimide (SPI) polyelectrolyte containing chalcone group was prepared and fabricated on an alumina electrode pretreated with chalcone-containing silane-coupling agent. SPI films with bis(tetramethyl)ammonium 2,2'-benzidinedisulfonate ($Me_4N$-BDS)/4,4'-diaminochalcone (DAC)/pyromellitic dianhydride (PA)= 90/10/100 possessed very linear response(Y = -0.04528X+7.69446, $R^2=0.99675$) and showed resistance changing from 4.48 to $2.1k{\Omega}$ between 20 and 95 %RH. The response time for absorption and desorption measurements between 33 and 94 %RH% was about 79 s, which affirmed the high efficiency of crosslinked SPI film for rapid detection of humidity. A negative temperature coefficient showing $-0.49%RH/^{\circ}C$ was found and proper temperature compensation should be considered in future applications. Moreover, pretreatment of the substrates with chalcone-containing silane-coupling agent was performed to improve the water durability and the stability of the humidity sensors at a high humidity and a high temperature and long-term stability for 480 h. The crosslinked SPI films anchored to electrode substrate could be a promising material for the fabrication of efficient humidity sensors with superior characteristics compared to the commercially available sensors.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.215-220
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• 2001

Amorphous Ti-Si-N films of approximately 200 and 650 thickness were reactively sputtered on Si wafers using a dc magnetron sputtering system at various $N_2$/Ar flow ratios. Their barrier properties between Cu (750 ) and Si were investigated by using sheet resistance measurements, XRD, SEM, RBS, and AES depth profiling focused on the effect of the nitrogen content in Ti-Si-N thin film on the Ti-Si-N barrier properties. As the nitrogen content increases, first the failure temperature tends to increase up to 46 % and then decrease. Barrier failure seems to occur by the diffusion of Cu into the Si substrate to form Cu$_3$Si, since no other X- ray diffraction intensity peak (for example, that for titanium silicide) than Cu and Cu$_3$Si Peaks appears up to 80$0^{\circ}C$. The optimal composition of Ti-Si-N in this study is $Ti_{29}$Si$_{25}$N$_{46}$. The failure temperatures of the $Ti_{29}$Si$_{25}$N$_{465}$ barrier layers 200 and 650 thick are 650 and $700^{\circ}C$, respectively.ely.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.145-151
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• 2016

In response to the cavitation caused by the partial vacuum caused by the fluid flow, a paint was developed by dispersing the lamella-shaped glass-flake in resin for anti-cavitation. This composite paint was developed by using the inorganic filler (lamella shaped glass-flake) and the NBR (Acrylonitrile-butadiene rubber) which was modified epoxy resin. Especially, the glass-flake was a thin film with a thickness of about 100~200 nm and length of about $20{\sim}30{\mu}m$, the aspect ratio was about 200 to 300 times that of the plate-shaped. So the paint for anti-cavitation have shown excellent performance in corrosion resistance. The results of evaluating anti-cavitation performance was below, tensile strength $4.8{\sim}6N/mm^2$ or more, rupture elongation 30% or higher, abrasive speed $10mm^2/h$ or less. In particular, it showed more than twice the superior performance compared to existing advanced foreign products in anti-cavitation performance evaluation.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.255-260
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• 2003

Silicon is known to accumulate in plants and results in greater resistance to diseases and insect pests. In this study, we investigated the effect of silicate fertilizer applied in soil on the development of powdery mildew of oriental melon. Oriental melon seedlings of four-leaf stage were transplanted and grown in a plastic film house. Silicate fertilizer was applied to maintain soil available $SiO_2$ level of 200 mg/kg one week before transplanting. Fungicide triflumizol was sprayed three times; one, two, and three weeks after transplanting. Sphaerotheca fuliginea was inoculated 2 weeks after transplanting. The number of infected leaf and the number of fungal colony in leaves were measured one, two, and three weeks after the inoculation. Three weeks after the fungal inoculation, in the treatment of fungicide triflumizol. infected leaf numbers and number of colony per leaf were reduced by 10 and 58%, respectively. In the silicate fertilizer treatment, infected leaf numbers and numbers of colony per infected leaf were suppressed only by 6 and 16%, respectively, and the efficacy was lower than that of the fungicide triflumizol. The combined treatment of silicate fertilizer and the fungicide suppressed powdery mildew more effectively, and infected leaf numbers and numbers of colony per leaf were reduced by 31 and 80%, respectively. These results indicate that although silicate fertilizer itself is not much effective in the suppression of powdery mildew, it can significantly enhance the efficacy of the fungicide.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.4
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• pp.1-7
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• 1999

We developed Fabrication process of embedded passive components in MCM-D substrate. The proposed MCM-D substrate is based on Cu/photosensitive BCB multilayer. The substrate used is Si wafer and Ti/cu metallization is used to form the interconnect layer. Interconnect layers are formed with 1000$\AA$ Ti/3000$\AA$ Cu by sputtering method and 3$\mu\textrm{m}$ Cu by electrical plating method. In order to form the vias in photosensitive BCB layer, the process of BCB and plasma etch using $C_2F_6$ gas were evaluated. The MCM-D substrate is composed of 5 dielectric layers and 4 interconnect layers. Embedded resistors are made with NiCr and implemented on the $2^{nd}$ dielectric layer. The sheet resistance of NiCr is controlled to be about 21 $\Omega$/sq at the thickness of 600$\AA$. The multi-turn sprial inductors are designed in coplanar fashion on the $4^{th}$ interconnect layer with an underpass from the center to outside using the lower $3^{rd}$ interconnect layer. Capacitors are designed and realized between $1^{st}$ interconnect layer and $2^{nd}$ interconnect layer. An important issue in capacitor is the accurate determination of the dielectric thickness. We use the 900$\AA$ thickness of PECVD silicon nitride film as dielectric. Capacitance per unit area is about 88nF/$\textrm {cm}^2$at the thickness of 900$\AA$. The advantage of this integration process is the compatibility with the conventional semiconductor process due to low temperature PECVD silicon nitride process and thermal evaporation NiCr process.

• Polymer(Korea)
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• v.33 no.1
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• pp.79-83
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• 2009

Thin electric insulation layers were coated on aluminum plates and aluminum condenser cases by plasma polymerization of HMDSO+$O_2$. Electric resistances of the films were higher than 1.0 M$\Omega$ if they are thicker than 0.5 ${\mu}m$ independently of the type of films but their surface morphologies and adhesion strengths were dependent on the process conditions. Deposition rate and adhesion strength of the films were dependent on $O_2$/HMDSO flow ratio and discharge power. The best result was obtained at $O_2$/HMDSO flow ratio of 4 and discharge power of 60 W. Adhesion strength could also be highly improved if aluminum was pre-treated in boiling water for 30 min through the formation of Al-O-Si bonding between the film and the aluminum surface. The coated films showed excellent chemical and thermal resistances.

• Polymer(Korea)
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• v.34 no.4
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• pp.313-320
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• 2010

New cinnamate group-containing copolymers for a self-curable, humidity-sensitive polyelectrolyte and polymeric anchoring agents were prepared by copolymerization of [2-[(methacryloyloxy) ethyl]dimethyl]propyl ammonium bromide(MEPAB), methyl methacrylate(MMA), 3-(trimethoxysilyl) propyl methacrylate(TMSPM) and 2-(cinnamoyloxy)ethyl methacrylate(CEMA). Photocrosslinkable copolymer composed of MEPAB/MMA/TMSPM/CEMA＝70/20/0/10 were used for humidity-sensitive membrane, and those of 50/0/20/30 and 0/0/50/50 were used for polymeric anchoring agents. 3- (Triethoxysilyl)propyl cinnamate(TESPC) was also used as a surface-pretreating agent for the comparison of capability of attachment of polyelectrolyte to the electrode surface with polymeric photocurable silanecoupling agents. Pretreatment of the electrode substrate with anchoring agents was performed to form a cinnamate thin film on the electrode through covalent bonds. When the sensors were irradiated with UV light, the anchoring of a polyelectrolyte into the substrate was carried out via the [2$\pi$+2$\pi$] cycloaddition. The resulting sensors using polymeric anchoring agents and TESPC showed water durability with increase of resistance by 60~85%, which is corresponding to the reduction of 2.25~3.15%RH, after soaking in water for 24 h. They showed good hysteresis (-0.2%RH), response time (90 sec) and long-term stability at high temperature and humidity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.201-206
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• 2019

This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide ($Ga_2O_3$) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating ${\beta}-Ga_2O_3$ (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of $10{\times}15mm^2$. Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length ($L_g$) of $2{\mu}m$ and a gate-drain spacing ($L_{gd}$) of $5{\mu}m$. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for $V_{gs}<-6V$, and the three-terminal off-state breakdown voltage was over 482 V in a $L_{gd}=5{\mu}m$ device measured in Fluorinert ambient at $V_{gs}=-10V$. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately $5.3{\times}10^5$. These device characteristics indicate the promising potential of $Ga_2O_3$-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.