• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.93-94
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• 2023

Through the industrial revolution that began in the 18th century, the amount of carbon dioxide in the atmosphere increased rapidly as humans used fossil energy such as coal and oil as fuel for steam engines and factory machines. The amount of carbon dioxide emitted while producing cement, the main material of concrete used in construction, is large enough to account for 5-8% of the world's carbon dioxide emissions. In this study, Non cement-based matrix were used to reduce carbon dioxide emissions from cement production. Red mud is an industrial by-product generated in the manufacturing process of aluminum hydroxide using bauxite, and more than 120 million tons are produced worldwide. In addition, red mud is a porous material that can be physically adsorbed, and causes a photocatalytic reaction of TiO₂ to remove harmful substances such as nitrogen oxide formaldehyde in the air and chemically adsorbs ammonia and hydrogen sulfide. Therefore, this study aims to examine the physical properties of the matrix by mixing red mud, an industrial by-product with good adsorption performance, into the Non cement-based matrix.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.424-424
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• 2008

Dye-sensitized Solar Cell (DSC) is a new type of solar cell by using photocatalytic properties of $TiO_2$. The electric potential distribution in DSCs has played a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage(Voc) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. $TiO_2$ thin films were deposited on the FTO substrate by Nd:YAG Pulsed Laser Deposition(PLD) at room temperature and post-deposition annealing at $500^{\circ}C$ in flowing $O_2$ atmosphere for 1 hour. The structural properties of $TiO_2$ thin films have investigated by X-ray diffraction(XRD) and atomic force microscope(AFM). Thickness of $TiO_2$ thin films were controlled deference deposition time and measurement by scanning electron microscope(SEM). Then we manufactured a DSC unit cells and I-V and efficiency were tested using solar simulator.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.3
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• pp.224-232
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• 2002

CdS-$TiO_2$ nano-composite sol was prepared by the sol-gel method in organic solvents at room temperature and further hydrothermal treatment at various temperatures to control the physical properties of the primary particles. Again, CdS-$TiO_2$ composite particulate films were made by casting CdS-$TiO_2$ sols onto $F:SnO_2$ conducting glass and then heat-treatment at $400^{\circ}C$. Physical properties of these 61ms were further controlled by the surface treatment with $TiCl_4$, aqueous solution. The photo currents and hydrogen production rates measured under the experimental conditions varied according to the $CdS/[CdS+TiO_2]$ mole ratio and the mixed-sol preparation method. For $CdS-TiO_2$ composite sols prepared in IPA, CdS particles were homogeneously surrounded by $TiO_2$ particles. Also, the surface treatment with $TiCl_4$ aqueous solution caused a considerable improvement in the photocatalytic activity, probably as a result of close contacts between the primary particles by the etching effect of $TiCl_4$. It was found that the photoelectrochemical performance of these particulate films could be effectively enhanced by this approach.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3761-3766
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• 2012

$Ag_2Se$-Graphene/$TiO_2$ composite was synthesized by a facile sonochemical method. The as-prepared products were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometer. During the reaction, both of the reduction of graphene oxide and loading of $Ag_2Se$ and $TiO_2$ particles were achieved. The as-prepared $Ag_2Se$-Graphene/$TiO_2$ composites possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously. Hence, in the photodegradation of rhodamine B (Rh.B), a significant enhancement in the reaction rate was observed with $Ag_2Se$-Graphene/$TiO_2$ composites, compared to the pure $TiO_2$. The high activity can be attributed to the synergetic effects of high charge mobility, and red shift in absorption edge of $Ag_2Se$-Graphene/$TiO_2$ composites.

• Membrane Journal
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• v.31 no.3
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• pp.184-199
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• 2021

As a branch of covalent organic frameworks (COF), covalent triazine frameworks (CTF) are inherently porous structures composed of networks of repeating hexagonal triazine rings fabricated via the ionothermal trimerization reaction. They also contain plenty of nitrogen functional groups that increase affinity for some chemicals while rejecting others. Because of their tunable properties, many researchers have synthesized and tested CTFs for gas and liquid separation processes. Various studies of novel CTFs, mixed CTF composites, and CTF membranes have experimented for gas adsorption/separation (e.g., CO₂, C₂H₂, H₂, etc.) and desalination. Some CTF studies have determined the limits and potentials through advanced computer simulations while subsequent experiments have tested CTFs for photocatalytic properties, suggesting recyclability for greater sustainability. In this review, the covalent triazine framework-based separation membrane is discussed.

• Journal of Microbiology and Biotechnology
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• v.32 no.9
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• pp.1195-1208
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• 2022

Silver nanoparticles (AgNPs) have potential applications in medicine, photocatalysis, agriculture, and cosmetic fields due to their unique physicochemical properties and strong antimicrobial activity. Here, AgNPs were synthesized using actinobacterial SL19 strain, isolated from acidic forest soil in Poland, and confirmed by UV-vis and FTIR spectroscopy, TEM, and zeta potential analysis. The AgNPs were polydispersed, stable, spherical, and small, with an average size of 23 nm. The FTIR study revealed the presence of bonds characteristic of proteins that cover nanoparticles. These proteins were then studied by using liquid chromatography with tandem mass spectrometry (LC-MS/MS) and identified with the highest similarity to hypothetical protein and porin with molecular masses equal to 41 and 38 kDa, respectively. Our AgNPs exhibited remarkable antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. The combined, synergistic action of these synthesized AgNPs with commercial antibiotics (ampicillin, kanamycin, streptomycin, and tetracycline) enabled dose reductions in both components and increased their antimicrobial efficacy, especially in the case of streptomycin and tetracycline. Furthermore, the in vitro activity of the AgNPs on human cancer cell lines (MCF-7, A375, A549, and HepG2) showed cancer-specific sensitivity, while the genotoxic activity was evaluated by Ames assay, which revealed a lack of mutagenicity on the part of nanoparticles in Salmonella Typhimurium TA98 strain. We also studied the impact of the AgNPs on the catalytic and photocatalytic degradation of methyl orange (MO). The decomposition of MO was observed by a decrease in intensity of absorbance within time. The results of our study proved the easy, fast, and efficient synthesis of AgNPs using acidophilic actinomycete SL19 strain and demonstrated the remarkable potential of these AgNPs as anticancer and antibacterial agents. However, the properties and activity of such particles can vary by biosynthesized batch.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.254-260
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• 2024

This study is to manufacture a titanium dioxide (TiO₂) photocatalyst by recycling sludge generated using titanium tetrachloride (TiCl₄) as a coagulant. Compared to general sewage, a TiCl₄ coagulant was applied to dyeing wastewater containing a large amount of non-degradable organic compounds to evaluate its performance. Then the generated sludge was dried and fired to prepare a photocatalyst (TFS). Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and nitrogen oxide reduction experiments were conducted to analyze the surface properties and evaluate the photoactive ability of the prepared TFS. After using titanium tetrachloride (TiCl₄) as a coagulant in the dyeing wastewater, the water quality characteristics were measured at 84 mg/L of chemical oxygen demand (COD), 10 mg/L of T-N, and 0.9 mg/L of T-P to satisfy the discharge water quality standards. The surface properties of the TFS were investigated and the anatase crystal structure was observed. It was confirmed that the ratio of Ti and O, the main components of TiO₂, accounted for more than 90 %. As a result of the nitric oxide (NO) reduction experiment, 1.56 uMol of NO was reduced to confirm a removal rate of 20.60 %. This is judged to be a photocatalytic performance similar to that of the existing P-25. Therefore, by applying TiCl₄ to the dyeing wastewater, it is possible to solve the problems of the existing coagulant and to reduce the amount of carbon dioxide generated, using an eco-friendly sludge treatment method. In addition, it is believed that environmental and economic advantages can be obtained by manufacturing TiO₂ at an eco-friendly and lower cost than before.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.554-558
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• 2008

$(1-x)SiO_2-(x)TiO_2$ composite fibers with various compositions of $TiO_2$ were prepared by electrospinning their sol-gel precursors of titanium (IV) iso-propoxide (TiP), and tetraethyl orthosilicate (TEOS). The surface morphology and structure of sintered composite fibers were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), simultaneous thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) and Fourier transform infrared spectroscopy (FT-IR). As the content of $TiO_2$ in $(1-x)SiO_2-(x)TiO_2$ system was increased the average diameter of composite fibers was proportionally increased. Also, the transformation of $TiO_2$ from anatase to rutile form was inhibited by the highly dispersed $TiO_2$ around $SiO_2$ particles up to $0.6SiO_2-0.4TiO_2$ composite fibers even after calcination at $1000^{\circ}C$. The photocatalytic activity of $SiO_2-TiO_2$ composite fibers was examined for the methylene blue (MB) decomposition which was confirmed using UV-vis/DRS spectra. The experiments demonstrated that the MB in aqueous solution was successfully photodegraded using $SiO_2-TiO_2$ composite nanofibers under UV-visible light irradiation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.227-231
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• 2010

Super hydrophilic $TiO_2$ thin films with photocatalytic property were successfully fabricated on a glass substrate by liquid phase deposition (LPD). The $TiO_2$ thin film formed nano particles on a surface at $70^{\circ}C$. As an immersion time in $TiF_4$ solution increased, the thickness of thin films gradually increased. $TiO_2$ thin film showed a water contact angel of below ca. $5^{\circ}$ and the transmittance of ca. 75~90 % in visible range. In addition, $TiO_2$ thin film showed the photocatalytic property to decompose methyl orange solution by the illumination of UV light. The surface morphologies, optical properties and contact angel of prepared thin films with a different immersion time were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.

• Korean Journal of Optics and Photonics
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• v.16 no.2
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• pp.168-173
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• 2005

Ag-doped $TiO_2$ thin films were prepared by RF magnetron co-sputtering method, and their physical and chemical properties were examined as a function of calcination temperature. XRD results showed that the crystallite size of Ag-doped films was smaller than that of the $TiO_2$ thin films. SEM results showed that the particle size of $Ag/TiO_2$ film was smaller and more uniform than pure $TiO_2$ film. The films had high transparency in the visible range. The films calcined at $600^{\circ}C$ were the anatase phase, and the films calcined at $900^{\circ}C$ were a mixture of anatase and rutile phases. The absorption edge of films calcined at $900^{\circ}C$ was red-shifted. This is due to the augmented absorption resulting from the phase transformation from anatase to rutile phase. And the transmittance of films decreased by the light scattering and absorption in the films. Photocatalytic activity of $Ag/TiO_2$ thin films was higher than that of the pure $TiO_2$ thin films.