• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.36-42
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• 1993

In the presence of $Ca^{2+}$ ion, the charge transfer (CT) interaction of nonionic surfactants, $nonylphenol-(ethylene oxide)_n\;[NP-(EO)_n; n = 11, 40, 100]$ with iodine in aqueous solution were investigated by UV-visible spectrophotometer. The characteristics of spectra depended on the concentration of $Ca^{2+}$ ion and the number of EO unit. Above CMC, the intensity of the CT band by the addition of $Ca^{2+}$ ion for the $NP-(EO)_{11}$ and $NP-(EO)_{40}$ increased and then decreased, while for the $NP-(EO)_{100}$ continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of $Ca^{2+}$ ion. These phenomena may be explained by the fact that the linear ethylene oxide (EO) chain, to be free configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca^{2+}$ ion.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.855-860
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• 1993

In the presence of SDS(sodium dodecyl sulfate), effect of $Ca^{2+}$on the interaction of NP-40EO[nonylphenol-(ethylene oxide)40] with iodine in aqueous solution were investigated by UV-visible spectrophotometer. In the presence of SDS, the intensity of interaction peaks were decreased and markedly increased by the addition of $Ca^{2+}$. Decrease of interaction peaks is caused by decrease of EO number to be interact with iodine per unit surface area of mixed micelle to the insertion of SDS and increase is attributed to the compactness of micelle in the presence of $Ca^{2+}$. These phenomena may be explained by the fact that the linear EO (ethylene oxide) chains, to be free in aqueous solution, could form a pseudo-crown ether structures of forming with $Ca^{2+}$ion.

• Polymer(Korea)
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• v.37 no.6
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• pp.736-743
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• 2013

Novel carbazole based copolymers were synthesized by Suzuki coupling polymerization. (Diphenylene)vinylene and n-octyl was introduced to carbazole as pendants for reducing band gap and improving solubility, respectively. Thermal, photoluminescence and electro-luminescence of copolymers were studied for applying the emitting layer of polymer light emitting diode (PLED). Maximum UV-vis absorption and photoluminescence (PL) emission wavelength of copolymers showed 333~340 nm and 409~464 nm in solution state, respectively. The relative quantum yield using 9,10-diphenylanthracene as a reference was 25.8%. These copolymers exhibited high thermal stability ($T_d$ = $350^{\circ}C$) and good film forming ability. Good luminance was obtained at voltages lower than 8 V and the onset voltage was observed at 4.0 V.

• Polymer(Korea)
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• v.34 no.4
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• pp.376-380
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• 2010

Donor-$\pi$-acceptor (D-$\pi$-A) type chromophore-based polymers were newly synthesized. These polymers exhibited absorption peak due to intramolecular charge transfer (ICT) in a visible range as well as absorption peak due to carbonyl group in both solution and film state by measuring UV visible spectra. The addition of $Eu^{3+}$ ion into the polymers induced red-shift in absorption due to ICT and the color changes from yellow to red in the solution and film were observed by naked eyes. The contents of crosslinking agent influenced the features and solubility of the polymers. In addition, the contents of crosslinking agent and the $Eu^{3+}$ ion addition improved film-forming ability.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.8-15
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• 2021

Transparent, photocatalytic, and self-cleaning TiO2 thin film is developed by TiO2 sol-gel coating on glass and polycarbonate (PC) substrates. Acetyl acetone (AcAc) suppresses the precipitation of TiO2 by forming a yellowish (complex) transparent sol-gel. XPS analysis confirms the presence of Ti2p and O1s in the thin films on glass and PC substrates. The TiO2-sol is prepared by stabilizing titanium (IV) isopropoxide (TTIP) with diethylamine and methyl alcohol. The addition of AcAcsilane coupling solution to the TiO2-sol instantaneously turns to yellowish color owing to the complexing of titanium with AcAc. The AcAc solution substantially improves the photocatalytic property of the TiO2 coating layer in MB solutions. The coated TiO2 film exhibits super hydrophilicity without and with light irradiation. The TiO2 thin film stabilized by adding 8.7 wt% AcAc shows the highest photo-degradation for methylene blue (MB) solution under UV light irradiation. Also, the optimum photocatalytic activity is obtained for the 8.7 wt% AcAc-stabilized TiO2 coating layer calcined at 450 ℃. The thin-films on glass exhibit fast self-cleaning from oleic acid contamination within 45 min of UV-light irradiation. The appropriate curing time at 140 ℃ improves the anti-fogging and thermal stability of the TiO2 film coated on PC substrate. The watermark-free PC substrate is particularly beneficial to combat fogging problems of transparent substrates.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.77-81
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• 2020

Resistive RAM (ReRAM) is a strong candidate for the next-generation nonvolatile memories which use the resistive switching characteristic of transition metal oxides. The resistive switching behaviors originate from the redistribution of oxygen vacancies inside of the oxide film by applied programming voltage. Therefore, controlling the oxygen vacancy inside transition metal oxide film is most important to obtain and control the resistive switching characteristic. In this study, we introduced an applying electric field into photochemical metal-organic deposition (PMOD) process to control the oxidation state of metal oxide thin film during the photochemical reaction by UV exposure. As a result, the surface oxidation state of FeOx film could be successfully controlled by the electric field-assisted PMOD (EFAPMOD), and the controlled oxidation states were confirmed by x-ray photoelectron spectroscopy (XPS) I-V characteristic. And the resistive switching characteristics with the oxidation-state of the surface region could be controlled effectively by adjusting an electric field during EFAPMOD process.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.46.2-46.2
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• 2017

We will present a discovery of an elliptical jellyfish galaxy in Abell 2670 (Sheen et al. 2017, ApJL, 840, L7). Our MUSE IFU spectra revealed a rotating gas disk in the center of the galaxy and long ionised gas tails emanating from the disk. Its one-sided tails and a tadpole-like morphology of star-forming blobs around the galaxy suggested that the galaxy is experiencing strong ram-pressure stripping in the cluster environment. Stellar kinematics with stellar absorption lines in the MUSE spectra demonstrated that the galaxy is an elliptical galaxy without any hint of a stellar disk. Then, the primary question would be the origin of the rich gas component in the elliptical galaxy. A plausible scenario is a wet merger with a gas-rich companion. In order to investigate star formation history of the system (the galaxy and star-forming blobs), we derived star-formation rate and metallicity from the MUSE spectra. Photometric UV-Optica-IR SED fitting was also performed using GALEX, SDSS, 2MASS and WISE data, to estimate dust and gas masses in the system. For a better understanding of star formation history and environmental effect of this galaxy, FIR/sub-mm follow-up observations are proposed.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.73-81
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• 1993

Adsorption process using granular activated carbon(GAC) has been considered as one of the most effective water treatment technologies to remove humic acid which is recon- niEed as trihalomethane(THM) precursor in chlorination. To design the most effective GAC process, it is necessary to conduct the test of adsor- ption performance by means of isothem, batch rate and column studies and to select the most effective activated carbon according to raw materials of GAC - lignite and coconut shell. The objective of this study is to investigate the adsorption performance of humid acid on two activated carbons - lignite activated carbon(LAC) and coconut shell activated car- bon(CAC) made in Korea. It is available to represent UV-abs and trihalomethane formation potential(THMFP) as concentration of humic acid due to good relationship. The adsorption capacity of humid acid is not concerned with surface area of activated carbon but with pore size related to about $100{\AA}$, and then LAC forming at the extent of mesopore is found to be eight times more effective in adsorption capacity than CAC forming at micropore. The adsorption capacity of LAC and CAC is better at pH 5.5 than at pH 7. Pore and surface diffusion coefficients calculated from the diffusion model are $7.61\times10^{-13}m^2/sec$, $3.52\times10^{-15}m^2/sec$ for CAC, and $3.38\times10^{-12}m^2$/sec and $Ds=1.48{\times}10^{-15}m^2/sec$ for GAC respectively. From the results of column test it shows that the performance of LAC is also better than CAC and the optimal EBCT(Empty Bed Contact Time) is 4.52min. and activated carbon removes selectively the components of humic acid to be easily formed to THM.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.241-246
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• 2001

Single or dual ion implantations were performed onto the transparent polyethylene terephthalate(PET) sheet, and the surface hardness and the light transmittance in the visual-UV range were examined. Nanoindentation showed that the surface hardness was the highest at about 50 nm depth from the surface and was increased by about 3 times when nitrogen ions were implanted with energy and dose of 90 keV and $1\times10^{15}\textrm{/cm}^2$ respectively. When dual ions such as He+N and N+C ions were implanted into PET, the hardness was increased even more than the case only N ions were implanted. Especially, when PET were implanted with N+C dual ions, the surface hardness of PET increased 5 times more as compared to when implanted with N ions alone. The light at the 550 nm wavelength(visual range) transmitted more than 85%, which is close to that of as-received PET, and at the wavelength below 300 nm(UV range) the rays were absorbed more than 95% as traveling through the sheet. implying that there are processing parameters which the ion implanted PET maintains the transparency and absorbs the UV rays. It can be considered that the increase in the hardness of polymeric materials is attributed to not only cross linking but also forming hard inclusions such as hard C-N compounds, as evidenced by the formation of the highest hardness when both N and C ions are implanted onto PET.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2966-2970
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• 2012

Fullerene/polystyrene ($C_{60}$/PS) nano particle was prepared by using emulsion polymerization. Styrene and fullerene were emulsified in aqueous media in the presence of poly(N-vinyl pyridine) as an emulsion stabilizer, and polymerization was initiated by water soluble radical initiator, potassium persulfate. The obtained nano particles have an average diameter in the range of 400-500 nm. The fullerene contents in the nano particle can be controlled up to 15 wt % by varying the feed ratio, which was confirmed by themogravimetric analysis (TGA) and elemental analysis (EA). The structure and morphologies of the $C_{60}$/PS nano particles were examined by various analytical techniques such as dynamic light scattering (DLS), scanning electron microscope (SEM), transmission electron microscope (TEM), electron diffraction (ED) pattern, X-ray powder diffraction (XRD), and UV spectroscopy. Unlike conventional $C_{60}$/PS particles initiated by organic free radical initiators, in which the fullerene is copolymerized forming a covalent bond with styrene monomer, the prepared $C_{60}$/PS nano particles contain pristine fullerene as secondary particles homogeneously distributed in the polystyrene matrix.