• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.815-820
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• 2009

Binary nanoemulsions which are defined as the, oil-droplet suspensions in binary solution ($H_2O$/LiBr), are developed to enhance the heat and mass transfer performance of absorption refrigeration systems. In this study, a novel two-step method is proposed to prepare the stable oil-in-binary solution (O/S) emulsion. Polymer is used as a steric stabilizer to stabilize the oil-droplets in a strong electrolyte ($H_2O$/LiBr). It is found that the thermal conductivity of the binary nanoemulsion is inversely proportional to the emulsion size while the concentrations of oil and $H_2O$/LiBr are less dominant for the thermal conductivity of binary nanoemulsions.

• Elastomers and Composites
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• v.50 no.2
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• pp.138-145
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• 2015

A series of wholly aromatic poly(hydroxyamide)s(PHAs), containing varying amounts of 2,6-dimethylphenoxy group and quinoxaline ring in the main chain, were synthesized by a direct polycondensation method. The inherent viscosities of the PHAs in either DMAc or DMAc/LiCl solution at $35^{\circ}C$ were found to be in the range of 1.02~1.90 dL/g. In the solubility study, we observed that PHA 1, PHA 2, and PHA 3 were dissolved in aprotic solvents such as DMAc, NMP, DMF, and DMSO with LiCl on heating; however, PHA 4, PHA 5, and PHA 6 could be dissolved in aprotic solvents on heating without LiCl. For poly(benzoxazole)s(PBOs), the 10% and maximum weight loss temperatures were in the range of $582{\sim}622^{\circ}C$ and $630{\sim}659^{\circ}C$, respectively. Residues of PBOs at $900^{\circ}C$ were found to be relatively high, which were in the range of 65.3~70.8%.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.822-824
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• 1998

The lithium polymer battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key point of the secondary battery system. The new type of polymer electrolyte was prepared under a dry Ar atmosphere by dissolving $LiCIO_4$ in a matrix of EC, PC and then dispersing polyacrylonitrile(PAN). Also adding some inorganic filler $Al_2O_3$. The dispersed solution heated at $120^{\circ}C$. The polymer electrolyte were characterized by EIS(Electrochemical Impedance Spectroscopy), TGA(Thermo Gravimetric analysis), DMA(Dynamic Mechanical Analyzer), DSC (Differential Scanning Calorimetry). The lithium ion yield is 0.29 when PAN-$Al_2O_3$ which was applied DC 5mV. The ionic conductivity of PAN, PAN-$Al_2O_3$ polymer electrolytes were showed $1.0{\times}10^{-4}S/cm$, $8.4{\times}10^{-4}S/cm$ at room temperature. When inorganic filler was added in the polymer electrolyte, ionic conductivity and lithium yield more larger than without inorganic filler.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.909-910
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• 2013

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.41.1-41.1
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• 2008

• 한국전기화학회:학술대회논문집
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• 2002.04a
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• pp.59-59
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• 2002

• 한국전기화학회:학술대회논문집
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• 2000.10a
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• pp.28-28
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• 2000

• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.73-73
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• 1999

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.220-228
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• 2018

This study introduced a carbon-free electrode for $Li-O_2$ cells with the aim of suppressing the side reactions activated by carbon material. Micro-particles of poly(3,4-ethylenedioxythiophene) (PEDOT), a conducting polymer, were used as the base material for the air electrode of $Li-O_2$cells. The PEDOT micro-particles were treated with $H_2SO_4$ to improve their electronic conductivity, and LiBr and CsBr were used as the redox mediators to facilitate the dissociation of there action products in the electrode and reduce the over-potential of the $Li-O_2$ cells. The capacity of the electrode employing PEDOT micro-particles was significantly enhanced via $H_2SO_4$ treatment, which is attributed to the increased electronic conductivity. The considerable capacity enhancement and relatively low over-potential of the electrode employing $H_2SO_4$-treated PEDOT micro-particles indicate that the treated PEDOT micro-particles can act as reaction sites and provide storage space for the reaction products. The cyclic performance of the electrode employing $H_2SO_4$-treated PEDOT micro-particles was superior to that of a carbon electrode. The results of the Fourier-transform infrared spectroscopic analysis showed that the accumulation of residual reaction products during cycling was significantly reduced by introducing the carbon-free electrode based on $H_2SO_4$-treated PEDOT micro-particles, compared with that of the carbon electrode. The cycle life was improved owing to the effect of the redox mediators. The refore, the use of the carbon -free electrode combined with redox mediators could realize excellent cyclic performance and low over-potential simultaneously.

• Polymer(Korea)
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• v.26 no.1
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• pp.45-52
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• 2002

The separator made from the blends of high density polyethylene (HDPE) and ultrahigh molecular weight polyethylene (UHMWPE) was prepared by wet processing to use as Li-ion secondary battery. We investigated effects of the blending of the polymers and the film extension on the mechanical properties of the separator. The mechanical strength of separator increased with increasing molecular weights and contents of UHMWPE, for instance about $1000 kg/\textrm{cm}^2$ with the five times extended film of 6 wt% UHMWPE. The pores of the separator were very uniform with the size of 0.1~$0.12\mu\textrm{m}$. The shut-down characteristic quickly increased at around $130^{\circ}C$ and the fusion temperature was $160^{\circ}C$, so it could be applied to the lithium ion secondary battery.