• Journal of Conservation Science
• /
• v.21
• /
• pp.49-58
• /
• 2007

Among the treatment results of test samples of the antique lacquer-ware, the treatment with PEG#3,350 40% solution displayed excellent effect with low shrinkage ratio; in weight gain the treatment with Sucrose 19%+Glycerin 1%(t-butanol 5% in water) solution showed consistent increase. However during the impregnation process of Sucrose, the weight of the testing samples decreased by dehydration because the inner part of the test samples and the treatment solution showed concentration gradient. Therefore, we concluded longer impregnation period should be necessary to prevent dehydration. Since both higher and lower molecular weight treatment chemicals could penetrate into the wood of the lacquer-ware, air drying and conditioning after impregnation treatment with high concentration chemicals would be possible, as well as vacuum freeze-drying.

• Journal of the Korean Vacuum Society
• /
• v.21 no.1
• /
• pp.41-47
• /
• 2012

Multi-walled carbon nanotubes (MWCNTs) incorporated polyacrylonitrile (PAN) and poly (methyl methacrylate) (PMMA) nanofibers were synthesized using electronspinning method. Effects of polymer concentration and applied voltage on the synthesis of PAN and PMMA nanofibers were systematically investigated. The structural characterization of PAN/MWCNTs and PMMA/MWCNTs composited nanofibers synthesized as a function of the MWCNTs concentration was performed by scanning electron microscopy and transmission electron microscopy. 5 wt% MWCNTs incorporated PAN and PMMA electrospun nanofiber exhibit best strength and stiffness.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.250.2-250.2
• /
• 2014

Currently, teeth whitening method which is applicable to dental surgery is that physician expertises give medical treatment to teeth directly dealed with a high concentration of hydrogen peroxide and carbamide peroxide. If hydrogen peroxide concentration is too high for treatment of maximized teeth whitening effect [1], it is harmful to the human body [2]. To the maximum effective and no harmful teeth whitening effect in a short period of time at home, we have observed the whitening effect using carbamide peroxide (15%) and a low-temperature atmospheric pressure plasma jet which is regulated by the Food and Drug Administration. The gas supplied conditions of the non-thermal atmospheric pressure plasma jet was with the humidified (0.6%) gas in nitrogen or air at gas flow rate of 1000 sccm. Also, the measurement of chemical species from the jet was carried out using the optical emission spectroscopy (OES), the evidence of increased reactive oxygen species compared to non-humidified plasma jet. We have found that the whitening effect of the plasma is very excellent through this experiment, when bovine teeth are treated in carbamide peroxide (15%) and water vapor (0.2 to 1%). The brightness of whitening teeth was increased up to 2 times longer in the CIE chromaticity coordinates. The colorimetric spectrometer (CM-3500d) can measure color degree of whitening effect.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1998.02a
• /
• pp.44-44
• /
• 1998

It was observed that the friction coefficient decreased with increasing Si concentration in the l ilms. Furthermore, the friction behavior became more s때ble even when very small amount of S Si of less than 0.5 at. % was incorporatA:회 By analyzing the composition of the debris f formed, we could show that the low and stabilized friction coefficient is in마nately relatA:었 w with the formation of the Si rich oxide debris. These result supports the mechanism that the h hydrated silica debris is the reason for low friction coefficient in humid environment. Second e evidence of the role of Si rich oxide debris could be found in the triOO-chemical reactions d during initial stage of triho-test. When the Si concen$\sigma$ation was less than 5 at.%, initial t transient period of high friction coefficient was commonly observed. Mter the transient period, m the friction coefficient becomes lower with increasing contact cycles. The initial $\sigma$ansient p peri여 becomes shorter and the starting and maximum friction coefficients in $\sigma$ansient 야,riod d decreased with increasing Si concentration. Composition of the debris on the wear scar s surface was analyzed by Auger spe따'Oscopy at v뼈ous stages in the initial transient period. W We observed that when the friction coefficient increased in earlier stage of the $\sigma$'ansient p period, iron and oxygen was observed in the debris. However, decrease in the 당iction c coefficient in the later stage of the transient period was associated with the formation of s silicon rich oxide debris. This result also supports the friction mechanism of Si-DLC films t that the formation of Si rich oxide debris results in low friction coefficient in ambient a atmosphere. atmosphere.

• Journal of the Korean Vacuum Society
• /
• v.14 no.3
• /
• pp.153-158
• /
• 2005

The effective mean free path model was adopted to examine the thickness effect on the thermoelectric properties of flash-evaporated n-type $Bi_2Te_{2.4}Se_{0.6}$ thin films. Annealing effects on the electron concentration and mobility were also studied, and their variations were analyzed in conjunction with antisite defects. Seebeck coefficient and electrical resistivity versus inverse thickness showed a linear relationship, and the mean free path was found to be $5120\AA$ Electron mobility was increased by annealing treatment and electron concentration was decreased considerably due to reduction of antisite defects, so that electrical conductivity was decreased and Seebeck coefficient was increased. When annealed at 473k for 1 hour, Seebeck coefficient and electrical conductivity were $-200\;\mu V/k\;and\;510\omega^{-1}cm^{-1}$, respectively. Therefore, the thermoelectric power factor was improved to be $20\times10^{-4}\;W/(mK^2)$.

• Journal of the Korean Vacuum Society
• /
• v.17 no.2
• /
• pp.156-159
• /
• 2008

The electrical characteristic of SiGe-on-SOI (SGOI) wafer with different Ge concentration were evaluated by pseudo-MOSFET. Epitaxial SiGe layers was grown directly on top of SOI with Ge concentrations of 16.2, 29.7, 34.3 and 56.5 at.%. As Ge concentration increased, leakage current increased and threshold voltage shifted from 3 V to 7 V in nMOSFET, from -7 V to -6 V in pMOSFET. The interface states between buried oxide and top of Si was significantly increased by the rapid thermal annealing (RTA) process, and so the electrical characteristic of SGOI wafer degraded. On the other hand, additional post RTA　annealing (PRA) showed that it was effective in decreasing the interface states generated by RTA processes and the electrical characteristic of SGOI wafer enhanced higher than initial state.

• Korean Journal of Food Science and Technology
• /
• v.23 no.2
• /
• pp.241-247
• /
• 1991

The objective of this experiment was to study the effect of dextrin on vacuum frying dried carrots. The concentrations of dextrin solution were 0%, 10%, 20%, 30% and the criteria for quality evaluation were sorption characteristics, rehydration power, color and crispness differences. The sorption characteristics were evaluated by Peleg's equation. Rehydration, color and crispness were determined by rehydration percentage, colorimetry and sensory evaluation, respectively. The dextrin pretreatment of carrot resulted in the reduction of adsorption rate and the equilibrium moisture content of dried carrot at various range of relative humidities, and the adsorption rate of samples pretreated with aqueous dextrin solution at different temperatures($4^{\circ}C,\;20^{\circ}C,\;30^{\circ}C$) were in the following decreasing order : control>10% dextrin>20% dextrin>30% dextrin. As the concentration of dextrin solution and ambient temperature increased, BET monomolecular layer moisture content decreased significantly. In addition, as the concentration of dextrin solution increased, the crispness intensity increased and the color of sample treated with 20% dextrin solution was similar to that of raw carrot.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.76-76
• /
• 2011

Polymer-fullerene based bulk heterojunction (BHJ) solar cells can be fabricated in large area using low-cost roll-to-roll manufacturing methods. However, because of the low mobility of the BHJ materials, there is competition between the sweep-out of the photogenerated carriers by the built-in potential and recombination within the thin BHJ film [12-15]. Useful film thicknesses are limited by recombination. Thus, there is a need to increase the absorption by the BHJ film without increasing film thickness. Metal nanoparticles exhibit localized surface plasmon resonances (LSPR) which couple strongly to the incident light. In addition, relatively large metallic nanoparticles can reflect and scatter the light and thereby increase the optical path length within the BHJ film. Thus, the addition of metal nanoparticles into BHJ films offers the possibility of enhanced absorption and correspondingly enhanced photo-generation of mobile carriers. In this work, we have demonstrated several positive effects of shape controlled Au and Ag nanoparticles in organic P3HT/PC70BM, PCDTBT/PC70BM, Si-PCPDTBT/PC70BM BHJ-based PV devices. The use of an optimized concentration of Au and Ag nanomaterials in the BHJ film increases Jsc, FF, and the IPCE. These improvements result from a combination of enhanced light absorption caused by the light scattering of the nanomaterials in an active layer. Some of the metals induce the plasmon light concentration at specific wavelength. Moreover, improved charge transport results in low series resistance.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.314-314
• /
• 2012

The dilute magnetic semiconductors (DMS) have been developed to multi-functional electro-magnetic devices. Specially, the Si based DMS formed by ion implantation have strong advantages to improve magnetic properties because of the controllable effects of carrier concentration on ferromagnetism. In this study, we investigated the deep level states of Fe- and Co-ions implanted Si wafer during rapid thermal annealing (RTA) process. The p-type Si (100) wafers with hole concentration of $1{\times}10^{16}cm^{-3}$ were uniformly implanted by Fe and Co ions at a dose of $1{\times}10^{16}cm^{-2}$ with an energy of 60 keV. After RTA process at temperature ranges of $500{\sim}900^{\circ}C$ for 5 min in nitrogen ambient, the Au electrodes with thickness of 100 nm were deposited to fabricate a Schottky contact by thermal evaporator. The surface morphology, the crystal structure, and the defect state for Fe- and Co- ion implanted p-type Si wafers were investigated by an atomic force microscopy, a x-ray diffraction, and a deep level transient spectroscopy, respectively. Finally, we will discuss the physical relationship between the electrical properties and the variation of defect states for Fe- and Co-ions implanted Si wafer after RTA.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.196-196
• /
• 2011

Molecular $N_2O$ has bee known to react over oxygen vacancy on a reduced rutile $TiO_2$(110)-1${\times}$1 surface to desorb as molecular $N_2$ leaving oxygen atom behind. In the present study, we investigated the reaction of $N_2O$ on rutile $TiO_2$(110) using temperature-programmed desorption (TPD). Our results indicate that $N_2O$ does not react over the oxygen vacancy under a typical UHV experimental condition. On a rutile $TiO_2$(110)-1${\times}$1 with a well-defined oxygen vacancy concentration of 5% ($2.6{\times}10^{13}/cm^2$), $N_2O$ desorption features show a monolayer peak maximum at 135 K followed by a small peak maximum at 170 K. When the oxygen vacancy is blocked with $H_2O$, the $N_2O$ peak at 170 K disappears completely, indicating that the peak is due to molecular $N_2O$ interacting with oxygen vacancy. The integrated amount of desorbed $N_2O$ plotted against the amount of adsorbed $N_2O$ however shows a straight line with no offset indicating no loss of $N_2O$ during our cycles of TPD measurements. In addition, our $N_2O$ uptake measurements at 70~100 K showed no $N_2$ (as a reaction product) desorption except contaminant $N_2$. Also, $H_2O$ TPD taken after $N_2O$ scattering up to 350 K indicates no change in the vacancy-related $H_2O$ desorption peak at 500 K showing no change in the oxygen vacancy concentration after the interaction with $N_2O$.