• 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.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.23-28
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• 1993

Thin films of soft magnetic Fe-Hf-C alloys with nanoscale crystallites were investigated in this study. The films were fabricated by an RF diode magnetron sputtering apparatus and subsequently annealed in vacuum. The soft magnetic properties of the films were observed to differ depending on the different substrates such as Corning 7059, $CaTiO_3$ and $Al_2O_3-TiC$ with various underlayer(Cr, $SiO_2$) thickness. This results may be due to the interdiffusion between the substrate and the magnetic layer and/or between the underlayer and the magnetic layer, rather than the microstructural change such as grain size. The Fe-Hf-C films with high permeability up to 4000(at 1 MHz) and saturation magnetization up to 16 kG were obtained in the vicinity of phase boundary between the crystalline and amorphous state when the size of ${\alpha}-Fe$ grains is about 5 nm. And also the films were found to have thermal stability up to $600^{\circ}C$.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1352-1354
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• 1998

$LiNbO_3$ transistor showed relatively stable characteristic, low interface trap density, and large remanent polarization. This paper reports ferroelectric $LiNbO_3$ thin films grown directly on p-type Si(100) substrates by 13.56 MHz rf magnetron sputtering system for FRAM applications. To take advantage of low temperature requirement for growing films, we deposited $LiNbO_3$ films lower than $300 ^{\circ}C$. RTA(Rapid Thermal Anneal) treatment was performed for as-deposited films in an oxygen atmosphere at $600^{\circ}C$ for 60 sec. We learned from X-ray diffraction that the RTA annealed films were changed from amorphous to poly-crystalline $LiNbO_3$ which exhibited (012), (015), and (022) orientations. The I-V characteristics of $LiNbO_3$ films before and after anneal treatment showed that RTA improved the leakage current of films. The leakage current density of films decreased from $10^{-5}$ to $10^{-7} A/cm^2$ at room temperature measurement. Breakdown electric field of the films exhibited higher than 500 kV/cm. The C-V curves showed the clockwise hysteresis represents ferroelectric switching characteristics. From C-V curves, we calculated dielectric constant of thin film $LiNbO_3$ as 27.5 which is close to that of bulk value.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.185-190
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• 2015

In this study, we fabricated the indium gallium zinc oxide (IGZO), zinc oxide (ZnO), aluminum zinc oxide (AZO). oxide and silver are deposited by magnetron sputtering and thermal evaporator, respectively transparency and energy bandgap were changed by the thickness of silver layer. To fabricate metal oxide metal (OMO) structure, IGZO sputtered on a corning 1,737 glass substrate was used as bottom oxide material and then silver was evaporated on the IGZO layer, finally IGZO was sputtered on the silver layer we get the final OMO structure. The radio-frequency power of the target was fixed at 30 W. The chamber pressure was set to $6.0{\times}10^{-3}$ Torr, and the gas ratio of Ar was fixed at 25 sccm. The silver thickness are varied from 3 to 15 nm. The OMO thin films was analyzed using XRD. XRD shows broad peak which clearly indicates amorphous phase. ZnO, AZO, OMO show the peak [002] direction at $34^{\circ}$. This indicate that ZnO, AZO OMO structure show the crystalline peak. Average transmittance of visible region was over 75%, while that of infrared region was under 20%. Energy band gap of OMO layer was increased with increasing thickness of Ag layer. As a result total transmittance was decreased.

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.224-228
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• 1998

Phase transition kinetics of nonstoichiometric amorphous titanium oxide thin films deposited by reactive sputtering was investigated after cooling down with various rate followed by l0min.-3hrs. annealing at $500^{\circ}C$~$600^{\circ}C$ After short duration and fast cooling. Magneli was the only crystalline phase because the oxidation rates of $TiO_{2-x}$, could be relatively slower than that of crystallization. When the films were cooled slowly between $500^{\circ}C$~$300{\circ}C$, Magneli was transformed into an anatase and stabilized, but directly into a rutile under fast cooling. Because the rutile also prevailed after cooling from $600^{\circ}C$, it was concluded that the rutile phase could be formed directly from Magneli as well as converted from the anatase. Changes in volume and surface morphology were observed related to crystallization and oxidation processduring heat treatment.

• Design & Manufacturing
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• v.13 no.4
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• pp.57-62
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• 2019

In this study, we investigated the halo surface defection of various phenomenon occurred during the injection molding process which is caused by the thinning of the product thickness and the importance of the appearance. Surface analysis was performed to observe the difference between the surface where defects appeared and the surface which did not appear. Based on these results, we analyzed the phenomenon of halo surface defects was caused by unstable flow of resin generated in injection molding and velocity change of flow front. Furthermore, we will conduct a clear analysis of halo surface defects through observations through optical microscopy and subsequent observations with atomic force microscope. It has been analyzed that halo in PP is due to the rheological difference between the crystalline and amorphous regions while that in PC/ABS is due to shear separation of PC and ABS.

• Journal of the Korean Wood Science and Technology
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• v.35 no.3
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• pp.45-52
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• 2007

The anatomical characteristics of Quercus variabilis woods carbonized at 310 to $350^{\circ}C$ were examined with an optical and scanning electron microscopy, and an X-ray diffraction analysis. Dimensional change and weight loss were also investigated. Volume of wood samples decreased with increasing the carbonization temperature, and checks were developed along with radial direction. Vessel diameter in tangential direction showed higher shrinkage than that in radial direction. Weight loss of samples increased with increasing carbonization temperature. Especially, the weight loss rapidly increased at the temperature ranging from 330 to $340^{\circ}C$. SEM study presented that the cell walls of samples carbonized at below $320^{\circ}C$ showed the layering structure. However, it was revealed that the layering structure was disappeared at $330^{\circ}C$ and over and showed an amorphous-like structure without cell wall layering. Interestingly, the existence of cellulose crystalline substance at $340^{\circ}C$ was confirmed by X-ray diffraction analysis and it was not detected at $350^{\circ}C$. Consequently, it is considered that the critical temperature for carbonization of wood was around $350^{\circ}C$.

• Journal of Pharmaceutical Investigation
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• v.41 no.3
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• pp.125-142
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• 2011

Solid dispersion, defined as the dispersion of one or more active ingredient in a carrier or matrix at solid state, is an efficient strategy for improving dissolution of poorly water-soluble drugs for enhancement of their bioavailability. Compared to other conventional formulations such as tablets or capsules, solid dispersion which can be prepared by various methods has many advantages. However, despite numerous studies which have been carried out, limitations for commercializing these products remain to be solved. For example, during the manufacturing process or storage, amorphous form of solid dispersion can be converted into crystalline form. That is, the dissolution rate of solid dispersion would continuously decrease during storage, resulting in a product of no value. To resolve these problems, studies have been conducted on the effects of excipients. In fact, modification of the solid dispersions to overcome these disadvantages has progressed from the first generation to the recent third generation products. In this review, an overview on solid dispersions in general will be given with emphasis on the various manufacturing processes which include the use of polymers and on the stabilization strategies which include methods to prevent crystallization.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.10
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• pp.894-898
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• 2016

Solution plasma is a unique method which provides a direct discharge in solutions. It is one of the promising techniques for various applications including the synthesis of metallic/non-metallic nanomaterials, decomposition of organic compounds, and the removal of microorganism. In the context of nanomaterial syntheses, solution plasma has been utilized to produce carbon nanoparticles and metallic-carbon nanoparticle systems. The main purpose of this study was to synthesize nickel nanoparticles embedded in a matrix of carbon particles by solution plasma in one-step using waste vegetable oil as the carbon source. The experimental setup was done by simply connecting a bipolar pulsed power generator to nickel electrodes, which were submerged in the waste vegetable oil. Black powders of the nickel nanoparticles-embedded carbon (NiNPs/Carbon) particles were successfully obtained after discharging for 90 min. The morphology of the synthesized NiNPs/Carbon was investigated by a scanning electron microscope, which revealed a good dispersion of NiNPs in the carbon-particle matrix. The X-ray diffraction of NiNPs/Carbon clearly showed the co-existence of crystalline Ni nanostructures and amorphous carbon. The crystallite size of NiNPs (through the Ni (111) diffraction plane), as calculated by the Scherrer equation was found to be 64 nm. In addition, the catalytic activity of NiNPs/Carbon was evaluated by cyclic voltammetry in an acid solution. It was found that NiNPs/Carbon did not show a significant catalytic activity in the acid solution. Although this work might not be helpful in enhancing the activity of the fuel cell catalysts, it is expected to find application in other processes such as the CO conversion (by oxidation) and cyclization of organic compounds.

• Archives of Pharmacal Research
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• v.29 no.11
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• pp.1055-1060
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• 2006

The objective of this study was to formulate itraconazole semisolid dosage forms and characterize their physicochemical properties. Itraconazole and excipients such as polysorbate 80, fatty acids, fatty alcohols, oils and organic acids were melted at $160^{\circ}C$. The fused solution was then cooled immediately at $-10^{\circ}C$ to make wax-like semisolid preparations. Their physicochemical attributes were first characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectrometry. The solubility of itraconazole in semisolid preparations and their dispersability in the simulated gastric fluid were also determined. Our semisolid preparations did not show any distinct endothermic peak of a crystalline form of itraconazole around $160-163^{\circ}C$. This suggested that it was changed into amorphous one, when it was formulated into semisolid preparations. In addition, the distinctive functional peaks and chemical shifts of itraconazole were well retained after processing into semisolid preparations. It could be inferred from the data that itraconazole was stable during incorporation into semisolid preparations by the hot melt technique. In particular, itraconazole semisolid preparations composed of polysorbate 80, fatty acids and organic acids showed good solubility and dissolution when dispersed in an aqueous medium. It was anticipated that the semisolid dosage forms would be industrially applicable to improving the bioavailability of poorly water-soluble drugs.