• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.201-203
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• 2008

ITO 투명전극을 양극으로 사용하고 PEDOT:PSS 고분자 물질위에 PVK와 Ir(ppy)3를 각각 host와 dopant로 사용하여 고분자 발광다이오드를 제작하였다. 전자 수송층의 역할로 TPBI, 음극으로 Al을 증착하여 최종적으로 ITO/PEDOT:PSS/PVK:Ir(ppy)3/TPBI/LiF/Al 구조를 갖는 녹색 인광 고분자 유기발광소자(PhPLED)를 제작하였다. 제작 된 소자의 발광부 dopant인 Ir(ppy)3도핑 농도에 따른 전기적 광학적 특성을 평가하였다. PVK:Ir(ppy)3를 host와 dopant system으로 dopant Ir(ppy)3의 도핑 양을 0.5 wt%에서2.5 wt%까지 씩 변화시키면서 최적의 농도를 찾고자 하였다. TPBI를 전자 수송층으로 사용 하였을 경우 최대 휘도는 약 8600 cd/$m^2$ (at 8V)이고, 전류밀도는 337mA/$cm^2$ 를 나타내었다.

• Macromolecular Research
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• v.14 no.1
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• pp.38-44
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• 2006

Vacuum deposited copper phthalocyanine (CuPc) was placed as a thin interlayer between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in a multi-layered, organic, light-emitting diode (OLEOs). The well-stacked CuPc layer increased the stability and efficiency of the devices. Thermal annealing after CuPc deposition and magnetic field treatment during CuPc deposition were performed to obtain a stacked-CuPc layer; the former increased the stacking density of the CuPc molecules and the alignment of the CuPc film. Thermal annealing at about 100$^{circ}C$ increased the current flow through the CuPc layer by over 25$\%$. Surface roughness decreased from 4.12 to 3.65 nm and spikes were lowered at the film surface as well. However, magnetic field treatment during deposition was less effective than thermal treatment. Eventually, a higher luminescence at a given voltage was obtained when a thermally-annealed CuPc layer was placed in the present, multi-layered, ITO/CuPc/NPD/Alq3/LiF/AI devices. Thermal annealing at about 100$^{circ}C$ for 3 h produced the most efficient, multi-layered EL devices in the present study.

• Macromolecular Research
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• v.16 no.8
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• pp.734-740
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• 2008

A new crosslinked, poly(acrylic acid)-based, dehydrating agent was synthesized through solution polymerization. The Taguchi method, a robust experimental design, was adopted to optimize the synthetic conditions based on the moisture and water absorbing capacities of the dehydrating agent. The method applied for the experiment was a standard L27 ($3^8$) orthogonal array with eight parameters and three levels. By analyzing the variance of the test results, the most effective parameters to control the moisture absorbing capacity (MAC) and its rate were the kind of alkaline base (LiOH, NaOH, or KOH) used as a neutralizing agent of the acrylic acid monomer and the degree of neutralization: The maximum MAC of 40% was achieved at only 2 hat $32^{\circ}C$ and 50% RH when KOH was used as a base and the degree of neutralization was 90%, respectively. However, the water absorbing capacity (WAC) of the resulting dehydrating agent was very low at 158 g/g, indicating that WAC is unaffected by MAC and its rate in this system. The surface morphologies of the agents were examined using scanning electron microscopy (SEM).

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.737-752
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• 2000

Wood-rotting basidiomycetous fungi are the most efficient degraders of lignin on earth. The white-rot fungus Phanerochaete chrysosporium has been used as a model microorganism in the study of enzymology and its application. Because of the ability of the white-rot fungus to degrade lignin, which has an irregular structure and large molecular mass, this fungus has also been studied in relation to degrading and mineralizing many environmental pollutants. The fungus includes an array of enzymes, such as lignin peroxidase (LiP), manganese-dependent peroxidase (MnP), cellobiose:quinone oxidoreductase, and $H_2O_2$-producing enzymes and also produces many other components of the ligninolytic system, such as veratryl alcohol (VA) and oxalate. In addition, the fungus has mechanisms for the reduction of degradation intermediates. The ligninolytic systems have been proved to provide reductive reactions as well as oxidative reactions, both of which are essential for the degradation of lignin and organopollutants. Further study on the white-rot fungus may provide many tools to both utilize lignin, the most abundant aromatic polymer, and bioremediate many recalcitrant organopollutants.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.247-259
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• 2017

This paper presents a fatigue assessment model that was developed for corroded reinforced concrete (RC) beams strengthened using prestressed carbon fiber-reinforced polymer (CFRP) sheets. The proposed model considers the fatigue properties of the constituent materials as well as the section equilibrium. The model provides a rational approach that can be used to explicitly assess the failure mode, fatigue life, fatigue strength, stiffness, and post-fatigue ultimate capacity of corroded beams strengthened with prestressed CFRP. A parametric analysis demonstrated that the controlling factor for the fatigue behavior of the beams is the fatigue behavior of the corroded steel bars. Strengthening with one layer of non-prestressed CFRP sheets restored the fatigue behavior of beams with rebar at a low corrosion degree to the level of the uncorroded beams, while strengthening with 20- and 30%-prestressed CFRP sheets restored the fatigue behavior of the beams with medium and high corrosion degrees, respectively, to the values of the uncorroded beams. Under cyclic fatigue loading, the factors for the strengthening design of corroded RC beams fall in the order of stiffness, fatigue life, fatigue strength, and ultimate capacity.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1511-1514
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• 2009

Organic light emitting layer in OLED device was formed by gravure printing process in this work. Organic surface coated by gravure printing typically showed relatively bad uniformity. Thickness and roughness control was characterized by applying various mixed solvents in this work. Poly (N-vinyl carbazole) (PVK) and fact-tris(2-phenylpyridine)iridium($Ir(ppy)_3$) are host dopant system materials. PVK was used as a host and Ir(ppy)3 as green-emitting dopant. To luminance efficiency of the plasma treatment on etched ITO glass and then PEDOT:PSS spin coated. The device layer structure of OLED devices is as follow Glass/ITO/PEDOT:PSS/PVK+Ir(ppy)3-Active layer /LiF/Al. It was printed by gravure printing technology for polymer light emitting diode (PLED). To control the thickness multi-printing technique was applied. As the number of the printing was increased the thickness enhancement was increased. To control the roughness of organic layer film, thermal annealing process was applied. The annealing temperature was varied from room temperature, $40^{\circ}C$, $80^{\circ}C$, to $120^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1077-1081
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• 2014

Polyacrylamide (PAM) -HgS nanocomposites were successfully prepared in polyacrylamide (PAM) matrix. From TEM and XRD characterizations, the synthesized HgS nanocrystals were chain-like spherical in shape with a diameter of about 40-60 nm and high crystalline quality. The quantum-confined effect of HgS nanocrystals was confirmed by UV-vis diffuse reflection spectra. The optical properties of products were investigated by using photoluminescence (PL) spectra, which showed that HgS nanocrystals exhibited good optical properties with maximum emission peak at about 640 and 650 nm at different reaction temperatures. The interaction of HgS nanocrystals with PAM was studied through FT-IR spectroscopy and TG analysis, which suggested that $Hg^{2+}$ could interact with functional groups of PAM. The experimental results indicated that PAM not only induced nucleation, but also inhibited further growth of HgS crystals and play an important role in the formation of PAM/HgS nanocomposites. In addition, the possible mechanism of HgS nanoparticles growth in PAM solution was also discussed.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.625-633
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• 2013

A type of polycyclotriphosphazene derivative (PCTPD), hexasulfanilic acid polycyclotriphosphazene (HSACP) and HSACP grafting SPEEK, sulfonated poly[2-(petachloropolycyclotriphosphazene-oxy)] etheretherketone (SPPSACPEEK) were synthesized, which were characterized by FTIR and $^{31}P$ NMR. Then three types of composite membranes such as HSACP grafting SPEEK, HSACP blending SPEEK, and nano $Y_2O_3$ doping and HSACP grafting SPEEK, respectively, were continuously prepared by solution-casting method. Comparing to SPEEK membranes with different amount of HSACP grafted or blended, grafting 15 wt% HSACP and doping 10 wt% nano $Y_2O_3$ SPEEK membrane conducted outstanding overall behavior of proton conductivity reaching $3.18 {\times}10^{-2}$ S/cm at $90^{\circ}C$ which was merely junior to SPEEK with 15 wt% HSACP grafted, methanol permeability coefficient getting $9.46{\times}10^{-8}cm^2{\cdot}s^{-1}$, swelling degree of 20.9% and solid residue of 98.98% which was superior to all specimen.

• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.365-369
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• 2013

With the wide application of ASP (alkaline-surfactant-polymer) flooding, the scaling becomes more and more serious, which is harmful to the oilfield and environment. In order to investigate the effects of HPAM on calcium carbonate crystallization, the crystallization behaviors of $CaCO_3$ in HPAM (Hydrolyzed polyacrylamide) solutions were studied and the composition and morphology of $CaCO_3$ crystal were investigated in different concentrations of polyacrylamide solutions. The crystal forms and morphologies of $CaCO_3$ were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that the crystallization of $CaCO_3$ is strongly influenced by the HPAM. The paper analyzed the internal cause, and the results show: The reasons leading to the change of morphology are carboxyl groups in polyacrylamide molecule and $Ca^{2+}$ in solution form chelates by coordination bond. And the chelates are adsorbed on the calcium hydroxide surfaces of solid-liquid interfaces so as to change the formation rate of calcium carbonate crystal nucleus. The research provides a reliable basis for the mechanism research of the scaling problem in the oil extraction process of ASP flooding and the adoption of scale inhibition and scale inhibitor.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.133-135
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• 2003

The removal of dissolved oxygen(DO) from water was studied using a poly(vinyliene fluoride)(PVDF) hollow fiber membrane contactor(HFMC) with the vacuum degassing process(VDP), Asymmetric porous PVDF hollow fiber membranes (HFM) for membrane contactor were prepared by a wet phase inversion method. In spinning of these PVDF hollow fibers, dimethy lacetamide (DMAc), LiCl and pure water were used as a solvent, a pore-forming additive and internal/external coagulant, respectively. The characteristics of the structure(pore size, porosity etc.) of the prepared PVDF HFMs as a function of concentration of pore-forming additive in polymer dope solution were studied. Also, the removal efficiency of DO from water according to flow rates of water, using PVDF HFMC with VDP, was studied. The performance of the asymmetric porous PVDF HFMC and a symmetric porous PP HFMC commercialized were compared. As a result, the asymmetric porous PVDF HFMC showed higher removal efficiency of DO than that of a symmetric porous PP HFMC.