• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.103-107
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• 2015

The effective glass frit composition used to absorb laser energy and to seal commercial dye-sensitized solar cell panel substrates has been previously developed using $V_2O_5-TeO_2$-based glass with 10 wt% ${\beta}$-eucryptite as a CTE controlling filler. The optimum sealing conditions are provided using a 3 mm beam, a laser power of 40 watt, a scan speed of 300 mm/s, and 200 irradiation cycles. In this study, the feasibility of the developed glass frit is investigated in terms of the sealing strength and chemical durability against the commercial iodide/triiodide electrolyte solution and fluorine-doped tin oxide (FTO) electrode in order to increase the solar cell lifetime. The sealing strength of the laser-sealed $V_2O_5-TeO_2$-based glass frit is $20.5{\pm}1.7MPa$, which is higher than those of thermally sealed glass frit and other reported glass frit. Furthermore, the developed glass frit is chemically stable against electrolyte solutions. The glass frit constituents are not leached out from the glass after soaking in the electrolyte solution for up to three months. During the laser sealing, the glass frit does not react with the FTO electrode; thus, the resistivity of the FTO electrode beneath the laser-sealed area remains the same.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.378-384
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• 2003

Etching species in CF$_4$/Ar plasma and the behavior of etching rate of Bi$_4$-$_{x}$L$_{x}$rTi$_3$O$_2$ (BLT) films were investigated in inductively coupled plasma (ICP) reactor in terms of etch parameters. The etching rate as functions of CF$_4$ contents showed the maximum 803 $\AA$/min at 20% CF$_4$ addition in CF$_4$/Ar plasma. The increase of RF power and DC bias voltage caused to an increase of etch rate. The variation of relative volume densities for F and he atoms were measured with the optical emission spectroscopy (OES). The chemical states of BLT were investigated with using X-ray photoelectron spectroscopy (XPS). XPS narrow scan analysis shows that La-fluorides remained on the etched surface. The presence of maximum etch rate at CF$_4$(20%)/Ar(80%) may be explained by the concurrence of two etching mechanisms such as physical sputtering and chemical reaction. The roles of he ion bombardment include destruction of metal (Bi, La, Ti)-O bonds as well as assistant for chemical reaction of metals with fluorine atoms.oms.

• Journal of Korean society of Dental Hygiene
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• v.6 no.4
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• pp.375-385
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• 2006

The purpose of this study is to analyze the influence of attitude of mothers on the dental health and behavior of dental health management on children on the dental caries of their children, and the questionnaire survey was implemented and analyzed for 202 children in fifth and sixth grades of two elementary schools in Ulsan City along with their mothers with the following outcome. 1. 80 students from entire subject students(39.6%) are subjects of dental caries with the average DT index shown to be $1.78{\pm}1.04$ and tended to have higher in the upper level of grade. 2. In the attitude of dental health management for mother, 95 students(47.0%) visited the dental clinic within 6 months with the main purpose of treatment, rather than preventive work, for 141 students(69.8%), and hey have high level of interests on the teeth condition of their children but they rarely take a close look at the dental condition for their children. 3. The efforts of mothers on preventing the dental caries by mothers showed in the sequence of regular instructions for brushing, limiting the sugar intake, fluorine coating, sealant, regular examination and the like and DT rate will be decreased by these kinds(p<0.05). 4. The number of dental caries of children with the attitude of mother in dental health showed noticeable differences statistically with respect to the brushing method, use of dental sanitation goods, scaling, visit to dental office and others(p<0.05). With the above conclusion, the attitude and behavior of mothers on dental care influences greatly on the dental health of children. Therefore, in order to improve the dental health of children, it would be important to recognize the importance of attitude and behavior of dental health for mothers for positive dental care with the support in policies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.208-212
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• 2013

Dye-sensitized solar cells (DSCs) have taken much attention due to their low cost and easy fabrication method compare to silicon solar cells. But research on cost effective DSC is prerequisite for commercialization. Fluorine doped tin oxide (FTO) which have been commonly used for electrode substrate as electron collector occupied most percentage of manufacturing cost. Therefore we studied FTO-less DSC using sputtered Ti deposited glass as photoelectrode instead of FTO to reduce manufacturing cost. Ti films sputtered on the glass for different time, 5 to 20 minutes with decreasing sheet resistance as deposition time increases. A light source illuminated to counter electrode in order to overcome opaque Ti films. The efficiency of DSC (Ti20) made Ti sputtered glass for 20 min as photoelectrode was 5.87%. There are no significant difference with conventional cell despite lower manufacturing cost.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.511-511
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• 2007

Low-emissivity (low-e) coatings with visible transparency have attracted increased interest m reducing heat radiation loss through window panes from ecological and sustainable aspects. $TiO_2$-silver transparent thin films for low-e have good properties for UV and IR blocking as well as photocatalyst compared to that with commercial UV blocking films such as fluorine doped oxide (FTO), antimony doped tin oxide (ATO), etc. In this study, transparent $TiO_2$-silver thin films were prepared by successive ink-jet printing of commercial nano silver and $TiO_2$ sol. The $TiO_2$ sol, as ink for ink-jet printing, were synthesized by hydrothermal process in the autoclave externally pressurized with $N_2$ gas of 200 bar at $120^{\circ}C$ for 10 hrs. The synthesized $TiO_2$ sols were all formed with brookite phase and their particle size was several to 30 nm. At first nano sized silver sol was coated on glass substrate, after that $TiO_2$ sol was coated by ink-jet printing. With increasing coating thickness of $TiO_2$-silver multilayer by repeated ink-jet coating, the absorbance of UV region (under 400nm) and IR region (over 700nm) also increase reasonably, compared to that with commercial UV blocking films.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.2
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• pp.137-144
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• 2015

Hypoxia is an important adverse prognostic factor for tumor progression and is a major cause of failure of radiation therapy. In case of short-term hypoxia, the metabolism can recover to normal, but if hypoxia persists, it causes irreversible cell damage and finally leads to death. So a hypoxia marker would be very useful in oncology. In particular, 2-nitroimidazole can be reduced to form a reactive chemical species, which can bind irreversibly to cell components in the absence of sufficient oxygen, thus, the development of radiolabeled nitroimidazole derivatives for the imaging of hypoxia remains an active field of research to improve cancer therapy result. 2-nitroimidazole based hypoxia marker, [$^{18}F$]FMISO holds promise for the evaluation of tumor hypoxia by Positron emission tomography (PET), at both global and local levels. In the present study, [$^{18}F$]FMISO was synthesized using an automatic synthesis module with high radiochemical purity (>99%) in 60 min. Immunohistochemical analysis using pimonidazole confirmed the presence of hypoxia in xenografted CT-26 tumor tissue. A biodistribution study in CT-26 xenografted mice showed that the increased tumor-to-muscle ratio and tumor-to-blood ratios from 10 to 120 min post-injection. In the PET study, [$^{18}F$]FMISO also showed increased tumor-to-muscle ratios from 10 to 120 min post-injection. In conclusion, this study demonstrates the feasibility and utility of [$^{18}F$]FMISO for imaging hypoxiain mouse colon cancer model using small animal PET.

• Korean Journal of Materials Research
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• v.25 no.3
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• pp.125-131
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• 2015

Fluorine-doped $SnO_2$ (FTO) thin film/Ag nanowire (NW) double layers were fabricated by means of spin coating and ultrasonic spray pyrolysis. To investigate the optimum thickness of the FTO thin films when used as protection layer for Ag NWs, the deposition time of the ultrasonic spray pyrolysis process was varied at 0, 1, 3, 5, or 10 min. The structural, chemical, morphological, electrical, and optical properties of the double layers were examined using X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, the Hall effect measurement system, and UV-Vis spectrophotometry. Although pure Ag NWs formed isolated droplet-shaped Ag particles at an annealing temperature of $300^{\circ}C$, Ag NWs covered by FTO thin films maintained their high-aspect-ratio morphology. As the deposition time of the FTO thin films increased, the electrical and optical properties of the double layers degraded gradually. Therefore, the double layer fabricated with FTO thin films deposited for 1 min exhibited superb sheet resistance (${\sim}14.9{\Omega}/{\Box}$), high optical transmittance (~88.6 %), the best FOM (${\sim}19.9{\times}10^{-3}{\Omega}^{-1}$), and excellent thermal stability at an annealing temperature of $300^{\circ}C$ owing to the good morphology maintenance of the Ag NWs covered by FTO thin films.

• Journal of Korean Neurosurgical Society
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• v.39 no.3
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• pp.176-182
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• 2006

Objective : This study concernes the usefulness of $^{11}C-methyl-L-and$ D-methionine[Met]-positron emission tomography[PET] for glioma grading and detection of recurrence in gliomas, compared with fluorine-18, 2-fluoro-deoxyglucose[FDG]-PET. Methods : Eighty patients underwent Met-PET study for evaluation of glioma : 37 astrocytomas [WHO grade II, 3; III, 8; IV, 26]. 27 oligodendrogliomas [WHO grade II, 16; III, 11]. and 12 suspicious recurrent gliomas. All images were taken within 2 weeks before operation. For suspicious recurrent cases on magnetic resonance images, both FDG-PET and Met-PET were performed. Results : In astrocytoma, Mean maximum standard uptake value[SUV] of region of interest[ROI] was not different between WHO grades [p=0.108]. but ROI/normal contralateral tissue SUV [T/N] ratio was statistically different between WHO grades [p=0.002]. T/N ratio was more closely related to visual scale than maximum SUV of ROI [p<0.001 and p=0.107 respectively]. In oligodendroglioma, there was no statistical difference between WHO grades in view of maximum SUV and T/N ratio. For recurrent gliomas, sensitivity of FDG-PET and Met-PET was 25% and 100%, while specificity of FDG-PET and Met-PET were 100% and 80%, respectively. Conclusion : Met-PET might be an appropriate tool for tumor grading in astrocytoma and be more sensitive for detection of recurrence in gliomas than FDG-PET.

• Journal of the Korean institute of surface engineering
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• v.40 no.4
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• pp.190-196
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• 2007

Dye sensitized solar cells(DSSC) are the most promising future energy resource due to their high energy efficiency, low production cost, and simple manufacturing process. But one problem in DSSC is short life time compared to silicon solar cells. This problem occurred from photocatalytic degradation of dye material by nanometer sized $TiO_2$ particles. To prevent dye degradation as well as to increase its life time, the transparent coating film is needed for UV blocking. In this study, we synthesized nanometer sized $TiO_2$ particles in sols by increasing its internal pressure up to 200 bar in autoclave at $120^{\circ}C$ for 10 hrs. The synthesized $TiO_2$ sols were all formed with brookite phase and their particle size was several nm to 30 nm. Synthesized $TiO_2$ sols were coated on the backside of fluorine doped tin oxide(FTO) glass by ink jet printing method. With increasing coating thickness by repeated ink jet coating, the absorbance of UV region (under 400 nm) also increases reasonably. Decomposition test of titania powders dispersed in 0.1 mM amaranth solution covered with $TiO_2$ coating glass shows more stable dye properties under UV irradiation, compared to that with as-received FTO glass.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.4 no.2
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• pp.57-64
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• 2018

${\omega}-[^{18}F]$-Fluorohexadecanoic acid (FHA) has been used for imaging of fatty acid metabolism of myocardium. To increase retention of radiolabeled fatty acid by blocking ${\beta}$-oxidation, methyl branched analogues have been used. In this experiment, we tried to synthesize 18F-labeled ${\alpha}-$, ${\beta}-$ and ${\omega}-FHA$ for imaging of the myocardial fatty acid metabolism. We synthesized ${\alpha}-$, ${\beta}-$ and ${\omega}$-mesylated methyl hexadecanoates and labeled with $^{18}F$ by reacting with $[^{18}F]$TBAF in acetonitrile at $80^{\circ}C$ for 10 min. Methyl ester group was removed by 1 M NaOH at $80^{\circ}C$ for 5 min. The yields of ${\alpha}-[^{18}F]$ and ${\omega}-[^{18}F]FHA$ were 25.5 and 45.5%, respectively [EOS]. However, ${\beta}-[^{18}F]FHA$ was not labeled at all due to a fast elimination reaction. The biodistribution study in ICR-mice showed that ${\omega}-[^{18}F]FHA$ has higher myocardial uptake and lower liver uptake than ${\alpha}-[^{18}F]FHA$. The electron-withdrawing effect of fluorine at ${\alpha}-$ position is believed to be the major factor affecting the biodistribution.