• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.297-304
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• 2013

Free-radical copolymerization of glycidyl methacrylate(GMA) and N-phthalimidoethyl acrylate(NPEA) were carried out at $60^{\circ}C$ in dimethylformamide(DMF) solution in the presence of benzoylperoxide(BPO) at low conversion. The polymers were characterized by IR and $^1H$-NMR. The compositions of the copolymer was analyzed by ultra violet(UV/Vis) spectrophotometry. The reactivity ratios of the monomer was determined by the application of Fineman-Ross(FR) and Kelen-T$\ddot{u}$d$\ddot{o}$s(KT) methods. The monomer reactivity ratios of the system and Alfrey-Price's resonance effect(Q) and polar effect(e) value for NIEA were determined as follow. The reactivity ratios of the monomer obtained from FR and KT are found to be $r_1$=0.87, $r_2$=0.98 and $r_1$=0.88, $r_2$=0.99 respectively. The Q and e values of poly(GMA-co-NPEM) calculated from $r_1$ and $r_2$ was Q= 1.31, e=0.75 respectively.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.3
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• pp.155-160
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• 2005

Kinetic studies were carried out for aquation of carbonatobis(ethylenediamine)cobalt(III) complexes in [H+] aqueous solution by UV/VIS-spectrophotometry. The rate law that in deduced from rate data is $rate=k_H{^+}[H^+]^{1.4}$ {$[Co(en)_2(CO_3)]^+$}1.0 where $k_H{^+}$ is the rate constant considering acidic catalyst, $H^+$ ion whose value is $0.241l{\cdot}mol^{-1}{\cdot}sec^{-1}$. The values of activation parameters Ea, ${\Delta}H^{\ast}$ and ${\Delta}S^{\ast}$ were $15.33Kcal{\cdot}mol^{-1}$, $14.52Kcal{\cdot}mol^{-1}$ and -57.49 e.u. respectively. On the basis of kinetic data and the observed activation parameters, we have proposed the mechanism that proceeds with two step protonations. The rate equation derived from the proposed mechanism has been in agreement with the observed rate equation. It has been seen that our modified mechanism for Harris's proton freequilibrium one prefer to the his concerted mechanism, and more the last product substitute $H_2O$ for $OH^-$ the Harris's mechanism in the acidity range 2 < pH < 5.

• Korean Journal of Materials Research
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• v.28 no.2
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• pp.101-107
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• 2018

Li-incorporated ZnO thin films were deposited by using ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of Li-incorporation on the performance of ZnO thin films, the structural, electrical, and optical properites of the ZnO thin films were analyzed by means of X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), Hall effect measurement, and UV-Vis spectrophotometry with variation of the Li concentraion in the ZnO sources. Without incorporation of Li element, the ZnO surface showed large spiral domains. As the Li content increases, the size of spiral domains decreased gradually, and finally formed mixed small grain and one-dimensional nanorod-like structures on the surface. This morphological evolution was explained based on an anti-surfactant effect of Li atoms on the ZnO growth surface. In addition, the Li-incorporation changed the optical and electrical properties of the ZnO thin films by modifying the crystalline defect structures by doping effects.

• Korean Journal of Materials Research
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• v.28 no.9
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• pp.516-521
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• 2018

Copper oxide thin films are deposited using an ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of substrate temperature and incorporation of a chelating agent on the growth of copper oxide thin films, the structural and optical properites of the copper oxide thin films are analyzed by X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), and UV-Vis spectrophotometry. At a temperature of less than $350^{\circ}C$, three-dimensional structures consisting of cube-shaped $Cu_2O$ are formed, while spherical small particles of the CuO phase are formed at a temperature higher than $400^{\circ}C$ due to a Volmer-Weber growth mode on the silicon substrate. As a chelating agent was added to the source solutions, two-dimensional $Cu_2O$ thin films are preferentially deposited at a temperature less than $300^{\circ}C$, and the CuO thin film is formed even at a temperature less than $350^{\circ}C$. Therefore the structure and crystalline phase of the copper oxide is shown to be controllable.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.147-147
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• 2016

In general, organic electrochromic (EC) materials have been known to be electrochemically unstable during the ionic exchange process. One effective method to realize stable EC materials is incorporating graphene derivatives in the polymer matrix, by using the strong interaction between graphene derivatives and polymer. However, previous studies are limited graphene derivatives. In this study, we developed a polymer-graphene derivative complex with the chemical assistance of a surfactant (octadecylamine, ODA). Surfactant-assisted graphene oxide (GO-ODA) was introduced as a protective layer on the electrochromic poly (3-hexyl thiophene) (P3HT) films by the Langmuir-Schaefer method. The deposition of GO-ODA protective layer with high coverage was confirmed by atomic force microscopy. The strong interactions between GO-ODA and P3HT were examined with UV-Vis spectrophotometry and X-ray photoelectron spectroscopy. Electrochemical and electrochromic investigations revealed that the GO-ODA layer greatly improved the long-term cyclability of the P3HT film. These findings imply that the GO-ODA complex has a significant role in creating stable EC cycling, due to its strong interaction with the P3HT film.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.484-491
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• 2017

Chalcogenide glasses have been investigated in their thermodynamic, structural, and optical properties for application in various opto-electronic devices. In this study, the $Sb_{20}Se_{80-x}Ge_x$ with x = 10, 15, 20, and 25 were selected to investigate the glass stability according to germanium ratios. The thermal, structural, and optical properties of these glasses were measured by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and UV-Vis-IR Spectrophotometry, respectively. The DSC results revealed that $Ge_{20}Sb_{20}Se_{60}$ composition showing the best glass stability theoretically results due to a lower glass transition activation energy of 230 kJ/mol and higher crystallization activation energy of 260 kJ/mol. The structural and optical analyses of annealed thin films were carried out. The XRD analysis reveals obvious results associated with glass stabilities. The values of slope U, derived from optical analysis, offered information on the atomic and electronic configuration in Urbach tails, associated with the glass stability.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2523-2531
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• 2009

Effects of some diacid, diamine and dinitro aromatic compounds on the structure and activity of adenosine deaminase (ADA) were investigated by UV-Vis spectrophotometry in 50 mM phosphate buffer at pH = 7.5 and 27 ${^{\circ}C}$ and molecular docking studies. The results showed that all tested ligands are showing inhibition; five ligands are uncompetitive and other two ligands are mixed of competitive and noncompetetive inhibitors with majority of competitive behavior. For the later case analysis was done based on competitive inhibition. Diacids have larger size and higher inhibition constant ($K_I$) relative to others. A logical correlation between calculated free energy of binding and experimental values was obtained for un-competitive. Experimental and calculated data showed that competitive inhibitors are distributed near the active site of enzyme and form several cluster of ranks, whereas uncompetitive inhibitors bind to the enzyme-substrate complex and distributed far from the active site. Results of structure-activity relationship showed that, larger, more hydrophobe, less spherical and more aromatic ligands have higher inhibition constants.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.2
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• pp.134-140
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• 2019

Oxide ($SnO_2$)/metal alloy (Cu(Ni))/oxide ($SnO_2$) multilayer films were fabricated using the magnetron sputtering technique. The oxide and metal alloy were $SnO_2$ and Ni-doped Cu, respectively. The structural, optical, and electrical properties of the multilayer films were investigated using X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectrophotometry, and 4-point probe measurements, respectively. The properties of the $SnO_2/Cu(Ni)/SnO_2$ multilayer films were dependent on the thickness and Ni doping of the mid-layer film. Since Ni atoms inhibit the diffusion and aggregation of Cu atoms, the grain growth of Cu is delayed upon Ni addition. For $250^{\circ}C$, the Haccke's figure of merit (FOM) of the $SnO_2$ (30 nm)/Cu(Ni) (8 nm)/$SnO_2$ (30 nm) multilayer film was evaluated to be $0.17{\times}10^{-3}{\Omega}^{-1}$.

• Elastomers and Composites
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• v.59 no.1
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• pp.1-7
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• 2024

Nanorod graphitic carbon nitride (g-C₃N₄) was synthesized by reacting melamine (C₃H₆N₆) with trithiocyanuric acid (C₃H₃N₃S₃) in distilled water for 10 h at room temperature. The resulting mixture was calcined at 550℃ for 2 h in an electric furnace under an air atmosphere. Nanorod g-C₃N₄/Ag₃PO₄ composites were prepared by adding nanorod graphitic carbon nitride (g-C₃N₄) powder, silver nitrate (AgNO₃), ammonia (NH₃·H₂O, 25.0-30.0%), and sodium hydrogen phosphate (Na₃HPO₄) to distilled water. The samples were characterized via X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The photocatalytic activities of the nanorod g-C₃N₄/Ag₃PO₄ composites were demonstrated via the degradation of organic dyes, such as methylene blue and methyl orange, under blue light-emitting diode irradiation and evaluated using UV-vis spectrophotometry.

• Journal of the Korean Chemical Society
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• v.68 no.3
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.