• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.855-859
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• 2023

Copper oxide (CuO) nanoparticles were successfully synthesized using a precursor in which industrial starch was impregnated with an aqueous solution of copper (II) nitrate trihydrate. The microstructure of the precursor impregnated with an aqueous solution of copper nitrate trihydrate was confirmed with a scanning electron microscope (SEM), and the particle size and the crystal structure of the copper oxide particles produced as the temperature of the heat treatment of the precursor increased was analyzed by X-ray diffraction (XRD) and the scanning electron microscope (SEM). As a result of the analysis, it was confirmed that the temperature at which the organic matter of the precursor is completely thermally decomposed is 450-490℃, and that the size and crystallinity of the copper oxide particles increased as the heat treatment temperature increased. The size of the copper oxide particles obtained through heat treatment at 500-800℃ during 1 hour was 100nm~2㎛. It was confirmed that the copper oxide crystalline phase is formed at a heat treatment temperature of 400℃, and only the copper oxide single phase existed up to 800℃. And it was also confirmed that the size of particles produced increased as the calcination temperature increased.

• Current Optics and Photonics
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• v.8 no.1
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• pp.38-44
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• 2024

Under the influence of atmospheric turbulence, a star's point image will shake back and forth erratically, and after exposure the originally small star point will spread into a huge spot, which will affect the ground calibration of the star sensor. To analyze the impact of atmospheric turbulence on the positioning accuracy of the star's center of mass, this paper simulates the atmospheric turbulence phase screen using a method based on a sparse spectrum. It is added to the static-star-simulation device to study the transmission characteristics of atmospheric turbulence in star-point simulation, and to analyze the changes in star points under different atmospheric refractive-index structural constants. The simulation results show that the structure function of the atmospheric turbulence phase screen simulated by the sparse spectral method has an average error of 6.8% compared to the theoretical value, while the classical Fourier-transform method can have an error of up to 23% at low frequencies. By including a simulation in which the phase screen would cause errors in the center-of-mass position of the star point, 100 consecutive images are selected and the average drift variance is obtained for each turbulence scenario; The stronger the turbulence, the larger the drift variance. This study can provide a basis for subsequent improvement of the ground-calibration accuracy of a star sensitizer, and for analyzing and evaluating the effect of atmospheric turbulence on the beam.

• Clean Technology
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• v.30 no.1
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• pp.13-22
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• 2024

In this study, blended 6,13-Bis(triisopropylsilylethynyl)pentacene (TP):2-Decyl-7-phenyl[1]benzothieno[3,2-b][1] benzothiophene (BT):Poly styrene (PS) TFT at different ratios were explored for their potential application as light absorption sensors. Due to the mixing of BT, both off current reduction and on/off ratio improvement were achieved at the same time. In particular, the TP:BT:PS (1:0.25:1 w/w) sample showed excellent light absorption characteristics, which proved that it is possible to manufacture a high-performance light absorption device. Through analysis of the crystal structure and electrical properties of the various mixing ratios, it was confirmed that the TP:BT:PS (1:0.25:1 w/w) sample was optimal. The results of this study outline the expected effects of this innovation not only for the development of light absorption devices but also for the development of mixed organic semiconductor (OSC) optoelectronic systems. Through this study, the potential to create a multipurpose platform that overcomes the limitations of using a single OSC and the potential to fabricate a high-performance OSC TFT with a fine-tuned optical response were confirmed.

• Korean Journal of Materials Research
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• v.34 no.7
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• pp.321-329
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• 2024

In this work, a series of BaTiO₃-based ceramic materials, Ba(Al_0.5Nb_0.5)_xTi_1-xO₃ (x = 0, 0.04, 0.06, 0.08), were synthesized using a standard solid-state reaction technique. X-ray diffraction profiles indicated that the Al+Nb co-doping into BaTiO₃ does not change the crystal structure significantly with a doping concentration up to 8 %. The doping ions exist in Al³⁺ and Nb⁵⁺ chemical states, as revealed by X-ray photoelectron spectroscopy. The frequency-dependent complex dielectric properties and electric modulus were studied in the temperature range of 100~380 K. A colossal dielectric permittivity (>1.5 × 10⁴) and low dielectric loss (<0.01) were demonstrated at the optimal dopant concentration x = 0.04. The observed dielectric behavior of Ba(Al_0.5Nb_0.5)_xTi_1-xO₃ ceramics can be attributed to the Universal Dielectric Response. The complex electric modulus spectra indicated the grains exhibited a significant decrease in capacitance and permittivity with increasing co-doping concentration. Our results provide insight into the roles of donor and acceptor co-doping on the properties of BaTiO₃-based ceramics, which is important for dielectric and energy storage applications.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2444-2451
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• 2024

This work demonstrates a new sol-gel approach for synthesizing PbO₂-doped zirconia using zircon mineral precursors. The streamlined methodology enables straightforward fabrication of the doped zirconia composites. Comprehensive materials characterization was performed using XRD, SEM, and TEM techniques to analyze the crystal structure, microstructure, and morphology. Quantitative analysis of the XRD data provided insights into the nanoscale crystallite sizes achieved, along with their relationship to lattice imperfections. Furthermore, the gamma-ray shielding capacity for the PbO₂-doped zirconia samples was estimated by the Monte Carlo simulation, which proves an increase in the gamma ray shielding properties by raising the Pb concentration. The linear attenuation coefficient increased between 0.467 and 0.499 cm^-1 (at 0.662 MeV) by increasing the Pb content between 11 and 21 wt%. By increasing the Pb content to 21 wt%, the synthesized composites' lead equivalent thickness reaches 2.49 cm. The radiation shielding properties for the synthesized composites revealed a remarkable performance against low and intermediate γ-ray photons, with radiation shielding capacity of 37.3 % and 21.4 % at 0.662 MeV and 2.506 MeV, respectively. As a result, the developed composites can be employed as an alternative shielding material in hospitals and radioactive zones.

• BMB Reports
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• v.40 no.5
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• pp.625-635
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• 2007

The enzyme squalene synthase (EC 2.5.1.21) catalyzes a reductive dimerization of two farnesyl diphosphate (FPP) molecules into squalene, a key precursor for the sterol and triterpene biosynthesis. A full-length cDNA encoding squalene synthase (designated as TcSqS) was isolated from Taxus cuspidata, a kind of important medicinal plants producing potent anti-cancer drug, taxol. The full-length cDNA of TcSqS was 1765 bp and contained a 1230 bp open reading frame (ORF) encoding a polypeptide of 409 amino acids. Bioinformatic analysis revealed that the deduced TcSqS protein had high similarity with other plant squalene synthases and a predicted crystal structure similar to other class I isoprenoid biosynthetic enzymes. Southern blot analysis revealed that there was one copy of TcSqS gene in the genome of T. cuspidata. Semi-quantitative RT-PCR analysis and northern blotting analysis showed that TcSqS expressed constitutively in all tested tissues, with the highest expression in roots. The promoter region of TcSqS was also isolated by genomic walking and analysis showed that several cis-acting elements were present in the promoter region. The results of treatment experiments by different signaling components including methyl-jasmonate, salicylic acid and gibberellin revealed that the TcSqS expression level of treated cells had a prominent diversity to that of control, which was consistent with the prediction results of TcSqS promoter region in the PlantCARE database.

• Journal of Conservation Science
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• v.32 no.4
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• pp.549-560
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• 2016

The purpose of this study is to identify the material characteristics of blackwares excavated from the Bonggok kiln site in Jinan-gun, Jeollabuk-do Province, South Korea, by scientific analyses and a reproduction experiment. Scientific analyses were conducted to determine the physical properties, chemical composition and for microscopic observation of blackwares. A reproduction experiment was also conducted by producing ceramic samples with black glaze, red ocher and limestone, and then cross sections of the samples were observed. The analysis results showed that all the excavated blackwares have similar properties such as chromaticity, specific gravity, absorption factor and porosity, but there is a difference depending on the crystallization of the ceramics. Thermal analysis showed that the exothermic peak was observed at about $1200^{\circ}C$, and crystal structure analysis indicated the presence of mullite. Hence, it can be concluded that the firing temperature of the excavated blackwares was around $1100-1200^{\circ}C$. Moreover, the glaze present on these blackwares has about 22% higher $Fe_2O_3$ content than those excavated from other places; however, the former has lower CaO content. For the reproduction experiment, samples were made using limestone as a flux and red ocher as a glaze. The results show that the cross section of the glaze layer of the reproduced sample have iron crystals with dendritic structures, similar to those present in the excavated black-wares. It is assumed that such iron crystals were formed during the process of melting and solidification of the iron oxide present in the blackwares.

• Journal of Conservation Science
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• v.37 no.1
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• pp.63-76
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• 2021

The purpose of this study is to scientifically analyze physicochemical characteristics of the roof tiles used for palaces in the Joseon Dynasty which stored in Changdeokgung material storage and Seooreung Jaesil and the modern handmade ones which made by N company to understand the differences between their manufacturing techniques. Through chromaticity, cross-sectional observation, component analysis, and crystal structure analysis, it was possible to confirm the physicochemical properties and fired properties of the roof tile. Roof tiles from the Joseon Dynasty have a wider colorimetric range and higher apparent porosity and water absorption, on average, than the modern roof tiles. The cross section of the Joseon Dynasty roof tiles shows that most clay minerals have not been vitrified, remaining in the form of atypical particles, while the modern roof tiles have denser clay materials. X-ray diffraction analysis identified low-temperature minerals such as micas in Joseon roof tiles but no peak of these minerals was observed in the modern roof tiles, implying that the modern ones are fired at higher temperature than the Joseon ones. Therefore, the modern roof tiles are fired at higher temperature and have higher density than the Joseon ones due to the use of pugmills. The general content of main ingredients was similar between the two. Additionally, the principal component analysis of trace elements in the Joseon roof tiles showed that most samples were from similar areas. It seems that the Joseon roof tiles were manufactured using soils supplied from a specific region at the same timeframe and their consistency in the content of principal components implies that they also have similar mix proportions of clay.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.564-573
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• 2022

Calcium carbonate (CaCO₃) exhibits three polymorphs: calcite with arhombohedral, vaterite with a spherical, and aragonite with a needle-like structure. Qualitative and quantitative analyses of the morphology of CaCO₃ are very important to investigate the synthesis of single-crystal vaterite and aragonite. In this work, the polymorphs of calcium carbonate were quantitatively analyzed using XRD. Pure vaterite and pure aragonite were synthesized and the peak distribution of a single phase was analyzed. The vaterite fraction of a mixture of calcite and vaterite was calculated based on the intensity of a specific diffraction peak, and compared to the results based on the peak area. The mean value of f_sV (the correction factor for the peak area of vaterite) was 0.654. The phase analysis of calcite-aragonite mixtures was performed, and the mean value of f_sA (the correction factor for the peak area of aragonite) was obtained as 0.6713. Using these factors, Eq. (24)~Eq. (32) for the quantitative analysis based on the total peak area of XRD were derived to calculate the phase contents of ternary phase CaCO₃. And three-component XRD section was defined considering overlapping sections.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.52-57
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• 2010

$BiFeO_3/Pb(Zr_{0.52}Ti_{0.48})O_3$(BFO/PZT) multilayer thin films have been prepared on a Pt/Ti/$SiO_2$/Si(100) substrate by chemical solution deposition. BFO single layer, BFO/PZT bilayer and multilayer thin films were studied for comparison. X-ray diffraction analysis showed that the crystal structure of all films was multi-orientated perovskite phase without amorphous and impurity phase. The leakage current density at 500 kV/cm was reduced by approximately four and five orders of magnitude by bilayer and multilayer structure films, compared with BFO single layer film. The low leakage current density leads to saturated P-E hysteresis loops of bilayer and multilayer films. In BFO/PZT multlayer film, saturated remanent polarization of $44.3{\mu}C/cm^2$ was obtained at room temperature at 1 kHz with the coercive field($2E_c$) of 681.4 kV/cm.