• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.564-569
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• 2010

Highly anti-reflective optical property has been focussed in the field of thin film and display because of increasing demands to the high transparency and clearness of optical component. In this study, to obtain anti-reflective property, the formation of aluminium oxide with nanoscaled flowerlike frame structure was introduced as oxide material monolayer on the substrate by hydrothermal synthesis through sol-gel method. The properties of coating layer were measured by the means of UV-Vis spectroscopy, FT-IR spectroscopy, XRD, and FE-SEM. The morphology of coating layer in alumina-sol coated samples was controlled by hydrothermal temperature and time with aid of ultrasound. It was found that high transparency and anti-reflective optical properties were obtained the formation of flowerlike nanoframe structure.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.706-714
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• 1995

Silicon oxide thin films were deposited by remote plasma chemical vapor deposition (RPCYD). The effect of the operating variables, such as plasma power, deposition temperature and partial pressure of reactant on the material Properties of the silicon oxide film was investigated. By XPS, it was found out that the film was suboxide (O/Si<2) and small amount of nitrogen due to the plasma excitation was accumulated at the Si/SiO$_2$interface. The amount of dangling bonds at the Si/SiO$_2$interfaces were measured by ESR and the concentration of hydrogen bond was obtained by SIMS and FT-IR. The bond angle distribution(d$\theta$/$\theta$) was shown to be similiar to thermal oxide above 20$0^{\circ}C$ but the etch rate was higher than that of the thermal oxides due to the structural difference and the stress between silicon substrate and silicon oxide film.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.3
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• pp.298-305
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• 2016

In this study, we treated pitch-based activated carbon fibers (ACFs) in hydrogen peroxide using electron beam (E-beam) irradiation to improve nitrogen monoxide (NO) sensing ability as an electrode material of gas sensor. The specific surface area of ACFs treated by E-beam irradiation with 400 kGy increased from $885m^2/g$ (pristine) to $1160m^2/g$ without any changes in structural property and functional group. The increase in specific surface area of the E-beam irradiated ACFs enhanced NO gas sensing properties such as response time and sensitivity. When the ACFs irradiated with 400 kGy, response time was remarkably reduced from 360 s to 210 s and sensitivity was increased by 4.5%, compared to the pristine ACFs. These results demonstrate convincingly that surface modification of ACFs using E-beam in hydrogen peroxide solution can enhance textural properties of ACFs and NO gas sensing ability of gas sensor at room temperature.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.95-100
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• 2014

In hypersonic aircraft, increase of aerodynamic heat and engine heat leads heat loads in airframe. It could lead structural change of aircraft's component and malfunctioning. Endothermic fuels are liquid hydrocarbon fuels which are able to absorb the heat load by undergoing endothermic reactions. In this study, exo-tetrahydrodicyclopentadiene was selected as a model endothermic fuel and experiments on endothermic properties were investigated with pore structure controlled zeolite catalyst using metal deposition. We secured the catalyst that had better endothermic performance than commercial catalyst. The object of this study is inspect catalyst properties which have effect on heat absorption improvement. Synthetic catalyst could be applied to system that use exo-THDCP as endothermic fuel instead of other commercial catalyst.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.226-232
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• 2012

Through the sampling four rice cultivars with differing amylose contents, the relationship between the structural and gelatinization properties of endosperm starches was analyzed. These rice varieties exhibited different chain length distribution ratio within the amylopectin cluster as well as varing amylose levels. The proportion of amylopectin short chains of in Goami cutlivars was higher than the other varieties, whereas the Goami 2 which shows amylose extender mutant properties in the endosperm showed the highest proportion of long chains. In X-ray diffraction analysis of rice starches, the Goami 2 variety displayed a B-type pattern whereas the other varieties were all A-type. Among the cultivars with high and normal rice starch levels, those with the higher amylose contents showed distinctly lower swelling. Goami 2 rice was found to have the highest onset and peak gelatinization temperature from the differential scanning calorimetry results. The four rice cultivars under analysis also showed different rates of hydrolysis by amyloglucosidase. These findings suggest that the composition and chemical structure of the starch content is a major determinant of both the gelatinization and functional properties of rice.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.423-428
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• 2014

We synthesized Fe-doped $TiO_2/{\alpha}-Fe_2O_3$ core-shell nanowires(NWs) by means of a co-electrospinning method and demonstrated their magnetic properties. To investigate the structural, morphological, chemical, and magnetic properties of the samples, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used, as was a vibrating sample magnetometer. The morphology of the nanostructures obtained after calcination at $500^{\circ}C$ exhibited core/shell NWs consisting of $TiO_2$ in the core region and ${\alpha}-Fe_2O_3$ in the shell region. In addition, the XPS results confirmed the formation of Fe-doped $TiO_2$ by the doping effect of $Fe^{3+}$ ions into the $TiO_2$ lattice, which can affect the ferromagnetic properties in the core region. For comparison, pure ${\alpha}-Fe_2O_3$ NWs were also fabricated using an electrospinning method. With regard to the magnetic properties, the Fe-doped $TiO_2/{\alpha}-Fe_2O_3$ core-shell NWs exhibited improved saturation magnetization(Ms) of approximately ~2.96 emu/g, which is approximately 6.1 times larger than that of pure ${\alpha}-Fe_2O_3$ NWs. The performance enhancement can be explained by three main mechanisms: the doping effect of Fe ions into the $TiO_2$ lattice, the size effect of the $Fe_2O3_$ nanoparticles, and the structural effect of the core-shell nanostructures.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.592-602
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• 2021

Thorium compounds have attracted immense scientific and technological attention with regard to both fundamental and practical implications, owing to unique chemical and physical properties like high melting point, high density and thermal conductivity. Hereby, we investigate the mechanical and thermodynamic stability and report on the structural, electronic and magnetic properties of new silicon-doped cubic ternary thorium phosphides ThSi_xP_1-x (x = 0, 0.25, 0.5, 0.75 and 1). The first-principles density functional theory procedure was adopted within full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential terms were treated within Generalized-Gradient-Approximation functional modified by Perdew-Burke-Ernzerrhof parameterizations. The proposed compounds showed mechanical and thermodynamic stable structure and hence can be synthesized experimentally. The calculated lattice parameters, bulk modulus, total energy, density of states, electronic band structure and spin magnetic moments of the compounds revealed considerable correlation to the Si substitution for P and the relative Si/P doping concentration. The electronic and magnetic properties of the doped compounds rendered them non-magnetic but metallic in nature. The main orbital contribution to the Fermi level arises from the hybridization of Th(6d+5f) and (Si+P)3p states. Reported results may have potential implications with regard to both fundamental point of view and technological prospects such as fuel materials for clean nuclear energy.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.363-363
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• 2014

Ruthenium (Ru) has attractive material properties due to its promising characteristics such as a low resistivity ($7.1{\mu}{\Omega}{\cdot}cm$ in the bulk), a high work function of 4.7 eV, and feasibility for the dry etch process. These properties make Ru films appropriate for various applications in the state-of-art semiconductor device technologies. Thus, it has been widely investigated as an electrode for capacitor in the dynamic random access memory (DRAM), a metal gate for metal-oxide semiconductor field effect transistor (MOSFET), and a seed layer for Cu metallization. Due to the continuous shrinkage of microelectronic devices, better deposition processes for Ru thin films are critically required with excellent step coverages in high aspect ratio (AR) structures. In these respects, atomic layer deposition (ALD) is a viable solution for preparing Ru thin films because it enables atomic-scale control of the film thickness with excellent conformality. A recent investigation reported that the nucleation of ALD-Ru film was enhanced considerably by using a zero-valent metallorganic precursor, compared to the utilization of precursors with higher metal valences. In this study, we will present our research results on the synthesis and characterization of novel ruthenium complexes. The ruthenium compounds were easy synthesized by the reaction of ruthenium halide with appropriate organic ligands in protic solvent, and characterized by NMR, elemental analysis and thermogravimetric analysis. The molecular structures of the complexes were studied by single crystal diffraction. ALD of Ru film was demonstrated using the new Ru metallorganic precursor and O2 as the Ru source and reactant, respectively, at the deposition temperatures of $300-350^{\circ}C$. Self-limited reaction behavior was observed as increasing Ru precursor and O2 pulse time, suggesting that newly developed Ru precursor is applicable for ALD process. Detailed discussions on the chemical and structural properties of Ru thin films as well as its growth behavior using new Ru precursor will be also presented.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1700-1702
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• 2004

Diamond films including nanocrystallites are grown by microwave plasma chemical vapor deposition using $O_2$ additives and negative substrate bias at growth step. Effects of growth parameters on film properties are characterized by Raman spectra, SEM, and AFM images. It is found that the surface roughness and the microstructure of grown films can be controlled by changing $O_2$ gas ratio. The I-V characteristics are also investigated in terms of growth conditions of diamond films. The surface roughness and the $sp^2$ phase of the grown diamond films turn out to be crucial factors for reducing leakage currents at diamond/metal interfaces.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.96.2-96.2
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• 2010

The surface morphology and structural properties of polycrystalline silicon (poly-Si) films made in-situ aluminum induced crystallization at various substrate temperature (300~600) was investigated. Silicon films were deposited by hot-wire chemical vapor deposition (HWCVD), as the catalytic or pyrolytic decomposition of precursor gases SiH4 occurs only on the surface of the heated wire. Aluminum films were deposited by DC magnetron sputtering at room temperature. continuous poly-Si films were achieved at low temperature. from cross-section TEM analyses, It was confirmed that poly-Si above $450^{\circ}C$ was successfully grown on and poly-Si films had (111) preferred orientation. As substrate temperature increases, Si(111)/Si(220) ratio was decreased. The electrical properties of poly-Si film were investigated by Hall effect measurement. Poly-Si film was p-type by Al and resistivity and hall effect mobility was affected by substrate temperature.