• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.575-582
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• 2000

The Electrical conduction and optical properties of Ta$_{2}$/O$_{5}$ thin films as the insulators in DRAM capacitors were studied. Liquid Ta/sib 2//O sub 5/ were prepared by a sol-gel processing and multiple layers were applied by spin-coating up to thickness of 800$\AA$. At annealing temperature of 300~$600^{\circ}C$ the electrical conduction and specific dielectric constant were discussed the behaivor of carrier were observed by the Thermally Stimulated Current (TSC) at the temperature range of 30~23$0^{\circ}C$. At annealing temperature of 300~$600^{\circ}C$ the samples were found to be amorphous below $600^{\circ}C$ and crystalline over it. The electrical strength was about 2.2 MV/cm at 40$0^{\circ}C$. In spite of noncrystallization over 50$0^{\circ}C$ the increasing of leakage current due to pinholes and increasing creak. The refractive index was obtained maximum (2.2) at 40$0^{\circ}C$. The dielectric constant was obtained maximum(18.6) at 40$0^{\circ}C$. TSC was observed one peak at the temperature range of 30~23$0^{\circ}C$ from sample at 40$0^{\circ}C$. In the case of collecting voltage the peak size is decreased in proportion to collecting voltage and then the peak may be thought carrier to be a ionic space charge.e.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.204.2-204.2
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• 2013

Wide band gap II-VI semiconductors have attracted the interest of many research groups during the past few years due to the possibility of their applications in light-emitting diodes and laser diodes. Among the II-VI semiconductors, ZnO is an important optoelectronic device material for use in the violet and blue regions because of its wide direct band gap (Eg ~3.37 eV) and large exciton binding energy (60 meV). F-doped ZnO (FZO) and undoped ZnO thin films were grown onto quartz substrate by the sol-gel spin-coating method. The doping level in the solution, designated by F/Zn atomic ratio of was varied from 0 to 5 in 1 steps. To investigate the effects of the structure and optical properties of FZO thin films were investigated using X-ray diffraction (XRD), UV-visible spectroscopy, and photoluminescence (PL). In the XRD, the residual stress, FWHM, bond length, and average grain size were changed with increasing the doping concentration. For the PL spectra, the high INBE/IDLE ratio of the FZO thin films doping concentration at 1 at.% than the other samples.

• Korean Journal of Materials Research
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• v.26 no.2
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• pp.73-78
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• 2016

$TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

• CELLMED
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• v.11 no.1
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• pp.6.1-6.7
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• 2021

In situ gelling devices, as they enter the body, are dosage forms in the shape of the sol but turn into gel types under physiological circumstances. Transition from sol to gel is contingent on one or a mixture of diverse stimuli, such as transition of pH control of temperature, irradiation by UV, by the occurrence of certain ions or molecules. Such characteristic features may be commonly employed in drug delivery systems for the production of bioactive molecules for continuous delivery vehicles. The technique of in situ gelling has been shown to be impactful in enhancing the potency of local or systemic drugs supplied by non-parenteral pathways, increasing their period of residence at the absorption site. Formulation efficacy is further improved with the use of mucoadhesive agents or the use of polymers with both in situ gelling properties and the ability to bind with the mucosa/mucus. The most popular and common approach in recent years has provided by the use of polymers with different in situ gelation mechanisms for synergistic action between polymers in the same formulation. In situ gelling medicine systems in recent decades have received considerable interest. Until administration, it is in a sol-zone and is able to form gels in response to various endogenous factors, for e.g elevated temperature, pH changes and ions. Such systems can be used in various ways for local or systemic supply of drugs and successfully also as vehicles for drug-induced nano- and micro-particles. In this review we will discuss about various aspects about use of these in situ gels as novel drug delivery systems.

• Genomics & Informatics
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• v.7 no.4
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• pp.187-194
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• 2009

Cytochrome P450 2E1 (CYP2E1) is a member of the cytochrome P450 superfamily, and it is a key enzyme responsible for the metabolic activation of many smallmolecular-weight compounds such as alcohol, which is classified as a human carcinogen. In this study, we identified 19 single nucleotide polymorphisms (SNPs) in CYP2E1 in Korean population. In these SNPs, we examined possible genetic association of CYP2E1 polymorphisms with HBV clearance and the risk of hepatocellular carcinoma (HCC). Five common polymorphic sites were selected, CYP2E1 polymorphisms at rs381-3867, rs3813870, rs2070673, rs2515641 and rs2480257, considering their allele frequencies, haplotype-tagging status and LDs for genotyping in larger-scale subjects (n=1,092). Statistical analysis demonstrated that CYP2E1 polymorphisms and haplotypes show no significant association with HBV clearance, HCC occurrence and onset age of HCC (p>0.05). Previous studies, however, have shown contradictory findings on associations of CYP2E1 polymorphisms with CYP2E1 activities and HCC risk. Comparing the contrasting results of previous researches suggest that CYP2E1 polymorphism is associated with CYP2E1 activity induced by ethanol, but is not directly associated with HCC risk. CYP2E1 variation/haploype information identified in this study will provide valuable information for future studies on CYP2E1.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1162-1164
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• 1995

In this paper, $TiO_2$-xmol%$V_2O_5$, x=0.0, 1.0, 2.0, 3.0 specimens are fabricated by Sol-Gel method. For the improvement of humidity sensitive characteristics for specimens, their microstructures are analysed and the optimum processing condition is established. Grain size increases with substitution rate of $V^{5+}$, on $Ti^{4+}$ site. Their humidity sensitive characteristics is good at 1mol% of $V_2O_5$ rate and heat-treated at $700^{\circ}C$. The capacitance of specimens decreases with frequency.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.102-105
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• 2012

The structural, electrical, and optical properties of layer-by-layer ZnO nanoparticles deposited using sol-gel spin coating technique were studied and now presented. Thicknesses of the thin films were varied by increasing the number of deposited layers. As part of our characterization process, XRD and FE-SEM were used to characterize the structural properties, current-voltage measurements for the electrical properties, and UV-Vis spectra and photoluminescence spectra for the optical properties of the ZnO thin films. ZnO thin films with thicknesses ranging from 14.2 nm to 62.7 nm were used in this work. Film with thickness of 42.7 nm gave the lowest resistivity among all, $1.39{\times}10^{-2}{\Omega}{\cdot}cm$. Photoluminescence spectra showed two peaks which were in the UV emission centered at 380 nm, and visible emission centered at 590 nm. Optical transmittance spectra of the samples indicated that all films were transparent (>88%) in the visible-NIR range. The optical band gap energy was estimated to be 3.21~3.26 eV, with band gap increased with the thin film thickness.

• Electrical & Electronic Materials
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• v.11 no.10
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• pp.46-52
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• 1998

In this study, polarization switching characteristics of Pb(ZrxTil-x)O3 (PZT) thin films were investigated. Switching times(ts) were found to be decreased as the Zr mol% was increased. But, the switching peak currents(Imax) showed the largest value at 50 mol% Zr. As a result of this experiment, ts was found to be depended on the remanent polarization and coercive field and also Imax strongly depended on the dielectric constant of PZT thin films. In order to investigate the partial switching kinetics of PZT thin films, short and relatively small voltage pulses were applied to the MFM(metalferroelectric metal) PZT capacitors and polarization switching curves were measured with a variation of the total width of the applied pulses. Also, the switching curves were measured at different applied voltages(4, 8, 10, 12 and 14 volts). As the applied voltages increased, ts and Imax were found to be decreased and increased, respectively. In case of fatigued specimen which we applied $\pm$10 volts square pulse for 1010 cycles, ts and Imax were found to be shorter and smaller than those of virgin specimens. This is due to the decrease of the remanent polarization and the increase of the coercive field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.339-342
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• 1998

Ferroelectric L $a_2$ $Ti_2$ $O_{7}$(LTO) thin films were prepared by chemical solution deposition processes. Acetylacetone was used as chelating agent and nitric acid was added in the stock solution to control hydrolysis and condensation reaction rate. The LTO thin films were spin-coated on Pt/Ti/ $SiO_2$/(100)Si and Pt/Zr $O_2$/ $SiO_2$/(100)Si substrates. After multiple coating, dried thin films were heat-treated for decomposition of residual organics and crystallization. The role of acetylacetone in Ti iso-propoxide stabilization by possibly substituting $O^{i}$Pr ligand was studied by H-NMR. B site-rich impurity phase, i.e. L $a_4$ $Ti_{9}$ $O_{24}$, was found after annealing, where its appearance was dependent on process temperature indicating the possible reaction with substrate. Dielectric and other relevant electrical properties were measured and the results were compared between modified sol-gel and MOD processes.s.s.

• Electrical & Electronic Materials
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• v.9 no.8
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• pp.836-850
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• 1996

In this study, we have analyzed structural analysis and measured ferroelectric characteristics of PZT thin films prepared by sol gel process with different sintering conditions and different Zr/Ti mot%. When the Zr mot% of PZT thin film was increased, it was found that the remanent. polarization and coercive field were decreased and increased, respectively. Also, the maxium dielectric constant of PZT(50/50) thin film was 786.8. We got double hysteresis(anti-fcrroelectric) curve from PbZrO$_{3}$ thin film. As heating rate goes up, pyrochlore phase of PZT thin film was decreased and dielectric and ferroelectric characteristics were improved. As a result of variation of sintering temperature and time 500.deg. C-800.deg. C and 5 sec.-8 hours, respectively, we got optimal sintering temperature and time. The optimium sintering temperature and time of conventional furnace method and rapid thermal processing method were 650.deg. C-700.deg. C for 30-60 minutes and 700.deg. C/20 seconds-2 minutes, respectively.