• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.476-482
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• 1988

Kinetic studies and theoretical investigations were made to illustrate the mechanism of the aquation of cis-[Co(en)$_2$YCl]$^{r+}$ (Y = NH$_3$, NO$_2^-$, NCS$^-$, $H_2O$) in $Hg^{2+}$ aqueous solution UV/vis-spectrophotometrically. The aquation of cis-[Co(en)$_2$YCl]$^{r+}$ have been found to be the second order for overall reaction as first order for each of substrate and Hg$^{2+}$+ catalyst. The reaction rate was increased in the order of Y=NH$_3$ < NCS$^-$- < $H_2O$ < $NO_2^-$, which are neighboring group of Cl. The step of bond formation was found to be the rate determining one, because the net charge of central metal ion run parallel with the observed rate constant. On the basis of rate determining step, kinetic data and the observed activation parameters, we have proposed the Id mechanism for the reaction system. The rate equation derived from the proposed mechanism has been in agreement with the observed rate equation.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.29-33
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• 2011

The current density in copper electroplating is directly related with the productivity and then to increase the productivity, the increase in current density is required. To obtain the high mass flow rate, rotating disk electrode(RDE) was employed. High rotational speed in RDE can increase the mass flow rate and then high speed electroplating was possible using RDE to control mass flow. Two types of cathode were used. One is RDE and another is rotating cylindrical electrode(RCE). A constant-current, constant-voltage and linear sweep voltammetry were applied to investigate current and voltage relationship. The maximum current density without evolution of hydrogen gas was increased with rotational speed. Over 400 rpm, maximum current density was higher than 1000 A/$m^2$. The diffusion coefficients of copper calculated from the slope of the plots are $5.5{\times}10^6\;cm^2\;s^{-1}$ at $25^{\circ}C$ and $10.5{\times}10^6\;cm^2\;s^{-1}$ at $62^{\circ}C$. The stable voltage without evolution of hydrogen gas was -0.05 V(vs Ag/AgCl). Additives were added to prevent dendritic growth on cathode deposits. The surface roughness was analyzed with UV-Vis Spectrophotometer. The reflectance of the copper surface over 600 nm was measured and was related with the surface roughness. As the surface roughness improved, the reflectance was also increased.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.612-622
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• 2014

In this study, we investigated the solubilization 4-chlorobenzoic acid in a wide range of temperature using a zwitterionic surfactant of lauryl sulfobetaine(LSB) and mixed surfactant systems. The effects of temperature and alkyl-group's length of surfactant molecule on the solubilization of 4-chlorobenzoic acid have been measured. The solubilization constants ($K_s$) were taken by the UV/Vis spectrophotometric method, plotting the total absorbance of the solution versus the surfactant concentration. The results show that the values of ${\Delta}G^o_s$ are all negative within the measured temperature range and decrease by increasing temperature, And also the measured values of ${\Delta}H^o_s$ and ${\Delta}S^o_s$ are all positive and increase by increasing temperature. The values of $K_s$ and thermodynamic parameters are simultaneously dependent on the temperature and the kinds of surfactant molecules. From the results we can postulate the solubilization site of 4-chlorobenzoic acid within the micelle.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.102-108
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• 2008

We have studied the properties of Ag/undoped ZnO (ZnO) multilayer thin films deposited on glass substrate by the facing targets sputtering method. In an attempt to find out the optimum conditions of the Ag thin film, which would be coated on the ZnO thin film, we investigated the changes of sheet resistance, transmittance and surface morphology as a function of deposition times and the substrate temperature. The electrical and optical characteristics of Ag/ZnO multilayers were evaluated by a four-point probe, a UV/VIS spectrometer with a spectral range of 390-770 nm, a X-ray Diffractometer (XRD), an atomic force microscope (AFM) and a Field Emission Scanning Electron Microscope (SEM), respectively. We were able to prepare the Ag/ZnO multilayer thin film with sheet resistance of 9.25 $\Omega/sq.$ and transmittance of over 80% at 550nm.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.67-74
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• 2016

The Prussian Blue Analogue(PBA) has three dimensional structure and the metal - organic framework material, and it has a variety configurations depending on the type of organic ligands. PBA has been receving an attention in the fields of biosensors, optical, catalytic, and hydrogen storage device. Also, it is an environmental friendly substance with a chemical stability. In addition, PBA is widely used in the filed of adsorption art since we can adjust the size of the fine pores. In this study, we synthesized $Mn_3[Fe(CN)_6]_2$, an organometallic framework chains by using a hydrothermal synthesis method. We used $K_4[Fe(CN)_6]$ and $MnCl_2$ as precursors. We also produced a manganese iron oxide, by baking the synthesized material. The effect of the size and shape of the particles was examined by controling pH of the precursor solution, the molar concentration of the precursor, and reaction time as the experimental variables. Synthesized absorbent was analyzed by XRD, SEM, FT-IR, UV-Vis, and TG / DTA to evaluate the adsorption properties of several dyes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.2
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• pp.73-77
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• 2012

Co-(0.8 wt%) and Ce-(0.4 wt%) doped cubic zirconia ($ZrO_2$ : $Y_2O_3$ = 80 : 20, 70 : 30, 60 : 40, 50 : 50 wt%) single crystals grown by a skull melting method were heat-treated in $N_2$ at $1000^{\circ}C$ for 5 hrs. The orange, yellowish brown and brown colored as-grown single crystals were changed into either brownish red, yellow and green color after the heat treatment. Before and after the heat treatment, the YSZ (yttria-stabilized zirconia) single crystals were cut for wafer form (${\phi}6.5mm{\times}t2mm$). The optical and structural properties were examined by UV-VIS spectrophotometer and X-ray diffraction. Absorption by $Ce^{3+}(^2F_{5/2,7/2}(4f){\rightarrow}^2T_g(5d^1))$, $Co^{2+}(^4A_2(^4F){\rightarrow}^4T_1(^4F)$ or $^4T_1(^4P))$ and $Co^{3+}$, change of ionization energy and lattice parameter were confirmed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.4
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• pp.153-159
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• 2015

Inorganic pigments have been received a great attention for various applications including paint, glazed ceramic ink, art tile, and building exterior due to their excellent thermal and chemical stability. Traditionally, the compositions of $PbCrO_4$, CdS and CdSe have been widely used as a yellow inorganic pigment. However, the use of these compositions has been restricted in recent years, because they contain harmful elements such as Cd, Cr, Pb and Se. In this study, new environment-friendly ceria-based pigment was synthesized using solid state reaction. Crystal structure and morphology of the obtained $Ce_{1-x}Zr_xBi_yO_{2-y/2}$ yellow pigment were analyzed using XRD and SEM, respectively. Substitutional effect of Zr and Bi on the pigment color was analyzed using UV-vis. spectrophotometer and CIE $L^*a^*b^*$ analysis. The crystal structure of the obtained pigments was dependent on the calcination temperature. The color characteristics and absorption band of the pigments were dependent on the calcination temperature and Zr, Bi contents. As a result, all the obtained yellow pigments showed the effective absorption ranged from ultraviolet to visible light, and $Ce_{0.44}Zr_{0.36}Bi_{0.20}O_{0.19}$ (x = 0.36, y = 0.20) pigment showed the most brilliant yellow color.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.515-522
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• 2010

A relation between antimicrobial activities and the formation constants of solid complexes of Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with tridentate Schiff base ligand, 4-hydroxy-3(1-{2-(benzylideneamino)-phenylimino}-ethyl)-6-methyl-2Hpyran-2-one (HL) derived from o-phenylene diamines, dehydroacetic acid (DHA) and p-chloro benzaldehyde have been studied. The ligand and metal complexes were characterized by elemental analysis, conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, $^1H$-NMR, UV-vis and mass spectra. From the analytical data, the stiochiometry of the complexes was found to be 1:2 (metal:ligand) with octahedral geometry. The molar conductance values suggest the nonelectrolytic nature of metal complexes. The X-ray diffraction data suggests monoclinic crystal system for Ni(II) and orthorhombic crystal system for Cu(II) and Co(II) complexes. The IR spectral data suggest that the ligand behaves as tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behavior (TG/DTA) and kinetic parameters calculated by Coats-Redfern method suggests more ordered activated state in complex formation. The protonation constants of the complexes were determined potentiometrically in THF:water (60:40) medium at $25^{\circ}C$ and ionic strength ${\mu}=0.1\;M$ ($NaClO_4$). Antibacterial activities in vitro were performed against Staphylococcus aureu and Escherichia coli. Antifungal activities were studied against Aspergillus Niger and Trichoderma. The effect of the metal ions and stabilities of complexes on antimicrobial activities are discussed.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.677-682
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• 2009

ZnS:Mn/ZnS core-shell quantum dots (QDs), were synthesized via a thermal decomposition reaction of organometallic precursors in a hot solvent mixture. The synthetic conditions of the quantum dots were monitored at various reaction temperatures for the core formation, while the shell formation temperature was fixed at 135$^{\circ}C$. The obtained colloidal nanocrystals at corresponding temperatures were characterized by UV-Vis, solution photoluminescence (PL) spectroscopies, and further obtained powders were characterized by XRD, HR-TEM, and EDXS analyses. The synthetic temperature condition to obtain the best PL emission intensity for the core-shell QD was 135$^{\circ}C$, for both core and shell formation. At this temperature, solution PL spectrum showed a narrow emission peak at 583 nm with a relative PL quantum efficiency of 42.15%. In addition, the measured spherical particle sizes for the ZnS:Mn/ZnS nanocrystals via HR-TEM were in the range of 4.0 to 5.4 nm, while ellipsoidal particles were obtained at 150$^{\circ}C$.

• Conservation Science in Museum
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• v.11
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• pp.61-72
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• 2010

This is the analysis of material dyed with Korean yellow dyes such as tumeric, amur cork tree, goldthread, gardenia, and the flowers of sophora japonica using nondestructive ultraviolet-visible and fluorescence spectrophotometry. In order to find out whether type of fabric or mordant influences analysis results, test fabrics were made using two types of fabric(silk and cotton) and dyed using three different mordants(no mordant, alum, iron). After analysis with UV-Vis reflectance spectrum on the dyed fabric, when the fabric was dyed with tumeric, amur cork tree and goldthread, the results were similar with no mordant and alum mordant, whereas there was a difference with an iron mordant. Also when the fabric was dyed using gardenia, different fabrics brought different results but there was no difference in results with mordants. On the other hand, when the fabric was dyed using the flowers of sophora japonica, there was no difference with fabrics but with mordants. After analysis with 3D-fluorescence spectrum, fabrics dyed with tumeric, amur cork tree and goldthread showed their own fluorescent spectrum with no regard to fabric and mordant; but with gardenia, there were differences with different fabrics whereas with the flowers of sophora japonica, there were differences with mordants.