• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.208-208
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• 2010

Indium zinc tin oxide (IZTO) thin films were studied as a possible alternative to indium tin oxide (ITO) films for providing low-cost transparent conducting oxide (TCO) for thin film photovoltaic devices. IZTO films were deposited onto glass substrates at room temperature. A dc/rf magnetron co-sputtering system equipped with a ceramic target of the same composition was used to deposit TCO films. Earlier studies showed that the resistivity value of $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20) films could be lowered to approximately $6{\times}10^{-4}ohm{\cdot}cm$ without sacrificing optical transparency and still maintaining amorphous structure through the optimization of process variables. The growth rate was kept at about 8 nm/min while the oxygen-to-argon pressure ratio varied from 0% to 7.5%. As-deposited films were always amorphous and showed strong oxygen pressure dependence of electrical resistivity and electron concentration values. Influence of forming gas anneal (FGA) at medium temperatures was also studied and proven effective in improving electrical properties. In this study, the chemical composition of the targets and the films varied around the $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20). It was the main objective of this paper to investigate how off-stoichiometry affected TCO characteristics including electrical resistivity and optical transmission. In addition to the composition effect, we have also studied how film properties changed with processing variables. IZTO thin films have shown their potential as a possible alternative to ITO thin films, in such way that they could be adopted in some applications where currently ITO and IZO thin films are being used. Our experimental results are compared to those obtained for commercial ITO thin films from solar cell application view point.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.34-41
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• 2005

We report some recent results in the rewritable Blu-ray Disc with enhanced overwrite cyclability by using the growth dominant eutectic based Ge(Sb70Te30)+Sb recording layer, GeN interface layer and write strategy optimization. We have developed phase-change optical media with appropriate write strategy for 36(i.e., 1X)-72Mbps(i.e., 2X) dual speed Blu-ray Disc system and fur the future high speed optical data storage. For recording layer, eutectic-based Ge(Sb70Te30)+Sb material was used and Sb/Te ratio and Ge content were optimized to obtain proper erasability and archival stability of recorded amorphous marks. The recording layer is wrapped up in GeN interface layers to obtain overwrite cyclability and higher crystallization speed. In addition, we designed appropriate write strategy so called Time-Shifted Multipulse (TSMP) write strategy where starting position of multipulse parts are shined from reference clock. With this write strategy, the jitter characteristics of the disc was improved and we found that leading edge jitter was improved much more than trailing edge jitter in 1X-2X speed recording. Finally, we investigated the higher speed feasibility of 144Mbps(i.e., 4X) by adopting some elemental doping to the eutectic based Ag-In-Sb-Te recording layer and structural optimization of constitution layers in Blu-ray Disc. In the paper, we report the effect of Sn addition for the feasibility of higher speed recording. The addition of Sn shows increases of the crystallization speed of phase change recording layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.127-127
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• 2011

We investigate the transparent TFTs using a transparent ZnSnO3 (ZTO)/Ag/ZTO multilayer electrode as S/D electrodes with low resistivity of $3.24{\times}10^{-5}$ ohm-cm, and high transparency of 86.29% in ZTO based TFTs. The Transparent TFTs (TTFTs) are prepared on glass substrate coated 100 nm of ITO thin film. On atomic layer deposited $Al_2\;O_3$, 50 nm ZTO layer is deposited by RF magnetron sputtering through a shadow mask for channel layer using ZTO target with 1 : 1 molar ratio of ZnO : $SnO_2$. The power of 100W, the working pressure of 2mTorr, and the gas flow of Ar 20 sccm during the ZTO deposition. After channel layer deposition, a ZTO (35 nm)/Ag (12 nm)/ZTO(35 nm) multilayer is deposited by DC/RF magnetron sputtering to form transparent S/D electrodes which are patterned through the shadow mask. Devices are annealed in air at 300$^{\circ}C$ for 30 min following ZTO deposition. Using UV/Visible spectrometer, the optical transmittances of the TTFT using ZTO/Ag/ ZTO multilayer electrodes are compared with TFT using Mo electrode. The structural properties of ZTO based TTFT with ZTO/Ag/ZTO multilayer electrodes are analyzed by high resolution transmission electron microscopy (HREM) and X-ray photoelectron spectroscopy (XPS). The transfer and output characterization of ZTO TTFTs are examined by a customized probe station with HP4145B system in are.

• Textile Coloration and Finishing
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• v.28 no.3
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• pp.219-229
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• 2016

The purpose of this study was to investigate the dyeability of silk fabrics with sweet potato stem leaf extract. To obtain the optimal dyeing conditions it was examined at various dyeing conditions(temperature, pH, time and bath ratio). The dyeability and the depths of shade which were evaluated in terms of K/S and CIELAB color difference values of the dyed and mordanted fabrics were also investigated. After dyeing, various color fastness(wash fastness, dry cleaning fastness, light fastness, rub fastness, and perspiration fastness) was measured and reviewed for UV protective, deodorant and antimicrobial functionality. The optimun output, as a result, was shown at 100% of dye concentration, $90^{\circ}C$ of dyeing temperature and 80 minutes of dyeing time while in terms of dye uptake depending on the kind of mordants and mordanting, it was found that among four mordants of $Alk(SO_4)_2$, $CuSO_4$, $SnCl_2$, and $FeSO_4$, post-mordanting with $SnCl_2$ showed the best results. Color fastness to dry cleaning, washing and rubbing was found strong at grade 4-5 and the grade to perspiration was as good as 3 while to light fastness was good at 4 as well. In aspects of functional properties, it showed excellent results of 98.3% UV protection rate and 88% deodorization rate. Antibacterial activity was 99.9% against staphylococcus aureus and 73.3% against klebisella pneumoniae. In conclusion, we validated that the dyestuffs from the disused sweet potato stem leaf extract would be useful as a natural dye material using the optimized conditions and dyeability for silk dyeing.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.670-678
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• 1996

The characterization of catalysts for the selective catalytic reduction(SCR) was investigated to remove NOx discharge from radioactive waste incinerator. The catalyst was prepared by impregnating $V_2O_5$, $MoO_3$, and $SnO_2$ on honeycomb shaped $TiO_2$. The effects of the type of catalysts, reaction temperature, feed composition, and mole ratio of $NH_3/NO$ on the reaction characteristics were evaluated in a laboratory scale reactor. The 10% $V_2O_5/TiO_2$ catalyst showed the highest NO to $N_2$ conversion of 94.4% at $350^{\circ}C$ and the temperature range for higher conversion was broadened by adding thermally stable promoters, $MoO_3$.

• Korean Journal of Materials Research
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• v.19 no.4
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• pp.192-197
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• 2009

Carbon nanotubes (CNT) were used as a catalyst support where catalytically active Pd and Pt metal particles decorated the outside of the external CNT walls. In this study, Pd and Pt nanoparticles supported on $HNO_3$-treated CNT were prepared by microwave-assisted heating of the polyol process using $PdCl_2$ and $H_2PtCl_6{\codt}6H_2O$ precursors, respectively, and were then characterized by SEM, TEM, and Raman. Raman spectroscopy showed that the acid treated CNT had a higher intensity ratio of $I_D/I_G$ compared to that of non-treated CNT, indicating the formation of defects or functional groups on CNT after chemical oxidation. Microwave irradiation for total two minutes resulted in the formation of Pd and Pt nanoparticles on the acid treated CNT. The sizes of Pd and Pt nanoparticles were found to be less than 10 nm and 3 nm, respectively. Furthermore, the $SnO_2$ films doped with CNT decorated by Pd and Pt nanoparticles were prepared, and then the $NO_2$ gas response of these sensor films was evaluated under $1{\sim}5\;ppm$ $NO_2$ concentration at $200^{\circ}C$. It was found that the sensing property of the $SnO_2$ film sensor on $NO_2$ gas was greatly improved by the addition of CNT-supported Pd and Pt nanoparticles.

• Journal of Conservation Science
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• v.34 no.1
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• pp.59-67
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• 2018

This study investigated manufacturing technique and provenance of the Gilt-bronze Seated Bhaisajyaguru (Medicine Buddha) Statue of Janggoksa Temple. The statue had the following : Cu(68.8%)-Sn(10.4%)-Pb(17.1%), it is similar to other medium or large Buddha statue. As results of comparison lead isotope ratio of sample with the provenance data were plotted in zone 3 of the South Korean galena map. According to this result of Bronze Buddha could be made into galena of the located in same area the temple. The results of this study were compared with the Bronze Bodhisattva statue of Goseongsa Temple. The manufacturing techniques were different based on the characteristics of Buddha statues and thus could be made into galena of the located in same area the temple.

• Tribology and Lubricants
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• v.31 no.6
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• pp.251-257
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• 2015

Heavy oil production is receiving significant attention because of increased demands for thermal power generation systems of the diesel engine and boilers. However, asphaltene, which is a heavy oil components (6-8 wt%), reduces the heat efficiency of the fuels owing to its agglomerated sludge of asphaltene during the burning process. Therefore, for hassle-free operation, we should develop asphaltene dispersants to suppress the formation of the sludge. We prepare variable salt-type polymeric dispersants using poly(isobutenyl succinic anhydride) and poly(amine) through both condensation esterification and acid-base neutralization reactions, which we subsequently evaluate for dispersing performance, using Turbiscan measurement. Total acid number (TAN) and total base number (TBN) of 75Lec-25SynDis.2 composed of lecithin and the prepared polymeric salt having the ratio of 3 : 1 are 18.9 and 33.7 mg KOH/g, respectively, which are comparable to those of the commercial dispersants (15.8 and 26.5 mg KOH/g). We determine the initial turbidity observed for 15 min of the polymeric dispersant was determined with transmittance (%), which can be calculated to separability number (SN). The SN value of 75Lec-25SynDis.2 is close to zero, which is superior to that of commercial dispersants and lecithin (0.015 and 0.017).

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.4-11
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• 2016

This study compares eight bronze spoons in the Goryeo Dynasty and analyzes their components and lead isotopes in order to confirm the relationship between their production sites and excavation sites. Most of the excavated spoons have elliptical heads, and their handles are categorized into two types. Bronze spoons are made of binary Cu-Sn alloys, but Pb is not added. The same artifacts can have different trace elements depending on location, and the spoons had high Ag content. According to an analysis of their lead isotopic ratio, they were made with raw materials produced in Zone 3 of the South Korean galena map. If the data of the trace elements in the raw ores of the bronze is accumulated, it can be used to indicate the provenance of the artifacts.

• Journal of Mechanical Science and Technology
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• v.20 no.4
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• pp.513-521
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• 2006

The performances of porous bearings under different operating conditions were experimentally investigated in this study. Material groups studied are 90%Cu + 10%Sn bronze and 1%C + % balance Fe iron-based self-lubricating P/M bearings at constant (85%) density. In the experiments, the variation of the coefficient of friction and wear ratio of those two different group materials for different sliding speeds, loads, and temperatures were investigated. As a result, the variation of the friction coefficient-temperature for both constant load, and constant sliding speed, friction coefficient-average bearing pressure, PV-wear loss and temperature-wear loss curves were plotted and compared with each other for two materials, separately. The test results showed that Cu-based bearings have better friction and wear properties than Fe-based bearings.