• Polymer(Korea)
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• v.29 no.1
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• pp.25-31
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• 2005

Cellulose acetate derivatives containing 6-(p-hexyloxyphenyl)carbonyl spirobenzopyran (CA-COSP) were prepared from base-catalyzed etherification of cellulose acetate, and their physical and photochromic properties were characterized. The degree of substitution of COSP was calculated from the amount of residual hydroxyl groups in cellulose acetate measured by the $^1H$-NMR and UV spectrometric data. It was ranging from 0.87 to 45.5% depending on the reaction condition. UV/vis spectrometry of the resulting CA-COSP revealed that the polymer shows a reversible color change by changing its color from colorless to blue upon UV irradiation forming a merocyanine structure, and returning back again to colorless spiropyran structure by visible light or by heat. The rate of color change was faster in solution than in the film. In the more polar solvent, the more stable was the resulting merocyanine, and the slower was the rate of reverse reaction to spiropyran. Compared to COSP blended with cellulose acetate, in which a phase separation was observed for samples containing more than 0.9 wt% of COSP, up to 48 wt% of COSP could be blended in CA-COSP without phase separation.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.57-63
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• 2016

Thermally induced phase separation (TIPS) and nonsolvent induced phase separation (NIPS) were simultaneously induced for the preparation of flat PVDF membranes. N-methyl-2-pyrrolidone (NMP) was used as a solvent and dibutyl-phthlate (DBP) was used as a diluent for PVDF. When PVDF was melt blended with NMP and DBP, crystallization temperature was lowered for TIPS and unstable region was expanded for NIPS. Ratio of solvent to diluent changed the phase separation mechanism to obtain the various membrane structures. Contact mode of dope solution with nonsolvent determined the dominant phase separation behavior. Since heat transfer rate was greater than mass transfer rate, surface structure was formed by NIPS and inner structure was by TIPS. Quenching temperature of dope solution also affected the phase separation mechanism and phase separation rate to result in the variation of structure.

• Polymer(Korea)
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• v.29 no.4
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• pp.408-412
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• 2005

Structure and characteristic of the films blended chitosan matrix with silk fibroin, extracted from Bombyx mori, were studied by X-ray diffraction, differential scanning calorimetry, FT-IR spectra analysis, SEM photographs, contact angle measurement and water absorbency in order to use as biomaterials. The blend films of $0\~30 wt\%$ fibroin content were prepared in acetic solution with $Li^+$ ion. It was found that the crystallinity of chitosan/fibroin blend films was decreased by the presence of intermolecular interactions such as hydrogen bonding between animo groups of chitosan and carbonyl groups of fibroin. As the proportion of fibroin in the blend increased, anhydrous crystalline phase of chitosan disappeared, and hydrated crystalline phase decreased, and $\beta$-structure crystalline phase of fibroin was formed. Therefore the blend films were crystallized into two different crystalline region of chitosan and fibroin. Surface hydrophilicity and water absorbency increased with blending fibroin. Above 20 $wt\%$ fibroin content, hydrogel film was formed. The surface and section of the film showed uniform microstructure on SEM photographs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.542-545
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• 2002

High performance organic electroluminescnet(EL) devices which are composed of organic thin multilayer films are fabricated. The basic structure is ITO/Emitting layer/LiF/Al in which have a blended emitting layer. The emitting layer is consisted of a host material(N,N' diphenyl-N,N' (3-methyl phenyl)-l,l'-biphenyl-4,4'diamine)(TPD)) and a guest emitting material(poly(3-hexylthiophehe)(P3HT)). We think that the energy transfer in blending layer occurred from TPD to P3HT. Red emitting multilayer EL devices were fabricated using tris(8-hydroxyqunolinate) aluminum$(Alq_3)$ as electron transport material. The device structure of ITO/blending layer(TPD+P3HT)$/Alq_3$/LiF/Al was employed. In the Voltage-current-luminance characteristics of multilayer device, the device tum on at the 2V and the luminance of $10{\mu}W/cm^2$ obtain at l0V. Red emission peak at 640nm was observed with this device structure. We have presented evidence that the excitation energy migration between a polymeric host and guest has to be explained. And by using multilayer, the red light emitting EL device enhances not only Voltage-current-luminance characteristic but also stability of device.

• Computers and Concrete
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• v.16 no.6
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• pp.865-880
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• 2015

Standard test method for bulk electrical conductivity (ASTM C1760) provides a rapid indication of the concrete's resistance to the penetration of chloride ions by diffusion. In this paper a new approach for assessing the bulk electrical conductivity of saturated specimens of hardened concrete is presented. The test involves saturating concrete specimens with a 5 M NaCl solution before measuring the conductivity of the samples. By saturating specimens with a highly conductive solution, they showed virtually the same pore solution conductivity. Different concrete samples yield different conductivity primarily due to differences in their pore structure. The feasibility of the method has been demonstrated by testing different concrete mixtures consisting ordinary and blended cement of silica fume (SF) and calcined perlite powder (CPP). Two standard test methods of RCPT (ASTM C1202) and Bulk Conductivity (ASTM C1760) were also applied to all of the samples. The results show that for concretes containing SF and CPP, the proposed method is less sensitive towards the variations in the pore solution conductivity in comparison with RCPT and Bulk Conductivity tests. It seems that this method is suitable for the assessment of the performance and durability of different concretes containing supplementary cementitious materials.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.11
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• pp.104-108
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• 2012

Flexible organic thin film solar cell device with Bulk Hetero-Junction (BHJ) structure was fabricated with blended conjugated polymer of PCDTBT : $PC_{71}BM$ as active layer. Surface of ITO anode for the organic solar cell device was treated with ozone. The organic solar cell device with bare ITO showed short circuit current density ($J_{sc}$) of $8.2mA/cm^2$, open-circuit voltage ($V_{oc}$) of 0.73V, fill factor (FF) of 0.36, and power conversion efficiency (PCE) of 2.16%, respectively. The organic solar cell device with ozone treated ITO anode revealed distinctively improved performance parameters:$J_{sc}$ of $9.8mA/cm^2$, $V_{oc}$ of 0.82V, FF of 0.43, PCE(${\eta}$) of 3.42%.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.72-78
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• 2002

Among the disposal techniques of inorganic wastewater sludges from industries most of sludges were dealed with buring underground inefficiently. But we have tried to recycle the resources that exhausted inorganic sludges were properly blended to certain ratioes to make lightweight aggregate, that means manufacturing of it can be possible through blending of various components, drying, sintering, cooling and crushing to certain sizes that are needed by consumers. As disposal method of inorganic wastewater sludge is changed to environmentally fraternative method, this method could be very useful to make lightweight aggregates for decoration of building and the other so many purposes of those usages. That could be economically useful due to expected income for buring costs of ordinary disposal method form industries and sales income after manufacturing it. The second important profit is saving foreign currency from purchasing self-developed lightweight aggregate insteas of importing expensive foreign product. This product will be also very impressive to user because of the fraternative lightweight to be composed of apatite structure that is important part of human body.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.123-130
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• 2008

A 3D structure production method for microstereolithography is a useful way that produces complex structures with flexible processes and low cost. Several UV curable resins were blended and the optimal resin for micro-lens fabricate was selected through viscosity, workability and transmission tests. It consists of 1, 6 - Hexanediol diacrylate with 15 Apha and Isobornyl acrylate for reducing some shrinkage. When fabricating a micro-lens array on large surface, some distortion of shape occurred because of the surface tension between cured part. To overcome this problem, the optimal processing conditions were derived from considering amount of the resin and surface tension. Large surface Micro-lens array, which are a type of elliptical convex and consist of 18,000 micro-lens in the range of 2cm*2cm were fabricated. The focal length to the X-axis and Y-axis were calculated. To verify the performance, measure an energy distribution of transmitted light from the Large surface Micro-lens array.

• Membrane and Water Treatment
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• v.7 no.4
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• pp.355-365
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• 2016

The improvement of fouling resistance of porous polymeric membrane is one of the most important targets in membrane preparation for water purification in many process like wastewater treatment. Membranes can be modified by various techniques, including the treatment of polymer material, blending of hydrophilic polymer into polymer solution, and post treatment of fabricated membrane. This research proposed the modifications of morphology and surface property of hydrophobic membrane by blending polyethersulfone (PES) with three polymeric additives, polyvinylpyrrolidone (PVP), Pluronic F127 (Plu), and Tetronic 1307 (Tet). PES hollow fiber membranes were fabricated via dry-wet spinning process by using a spinneret with inner and outer diameter of 0.7 and 1.0 mm, respectively. The morphology changes of PES blend membrane by those additives, as well as the change of performance in ultrafiltration module were comparatively observed. The surface structure of membranes was characterized by atomic force microscopy and Fourier transform infra red spectroscopy. The cross section morphology of PES blend hollow fiber membranes was investigated by scanning electron microscopy. The results showed that all polymeric additives blended in this system affected to improve the performances of PES membrane. The ultra-filtration experiment confirmed that PES-PVP membrane showed the best performance among the three membranes on the basis of filtration stability.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.560-564
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• 2001

Nowadays, according to the trend of a high performance of concrete structure, the research results have been announced for the purpose to make the high quality. With this respect, we began research to use the Ground Calcium slurry Carbonate (GCC) to a concrete admixtures which ground the limestone until about $1.5mutextrm{m}$. In this paper, we examined the quality of GCC to fine out the value in use as the concrete admixtures. And mechanical properties of concrete using cement blended with GCC, silica fume and mixed two were investigated. It was result from this study that air contents of concrete replaced with GCC were constant regardless of replacement ratio, but the more GCC it had the use of, the less slump was measured. Especially 10% GCC concrete had a good result of compressive strength. In case of mixture with GCC and silica fume, the workability and compressive strength don't seem to be any problems. In the scope of this study it was indicated that the most reasonable replacement with GCC was 10% of cement weight as concrete admixture.