• Polymer(Korea)
• /
• v.37 no.2
• /
• pp.162-166
• /
• 2013

Graphene-coated polymer particles have attracted research interests due to their emerging applications derived from their controlled structure and morphology. To control the properties of graphene oxide (GO)-polystyrene (PS) composite particles, the adsorption time and instantaneous adsorption conditions were investigated by varying their mixing method. Polystyrene particles prepared by emulsion polymerization were modified to have positive surface charge by adsorption of polyethylene imine (PEI) on the surface of PS particles. GO prepared by the chemical exfoliation method had negative surface charge from the oxygenated groups. The adsorption of the negatively charged GOs onto the positively charged PS particles was successfully completed, and it was found that a longer adsorption time and a greater difference in the instantaneous relative concentration led PS-GO particles to have more homogeneously coated surfaces without aggregation.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1229-1232
• /
• 1994

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. This paper describes the effects of lithium salts, plasticizer addition and temperature dependence of conductivity of PEO electrolytes. Polyethylene oxide(PEO) based polymer electrolyte films were prepared by solution casting an acetonitrile solution of preweighed PEO and Li salt. After solvent evaporation, the electrolyte films were vacuum-dried at $60^{\circ}C$ for 48h, the thickness of the films were $90{\sim}110{\mu}m$. The conductivity properties of prepared PEO electrolytes are summarized as follows. PEO electrolyte complexed with $LiClO_4$ shows the better conductivity of the others. $PEO-LiClO_4$ electrolyte when $EO/Li^+$ ratio is 8, showed the best conductivity. Optimum operating temperature of PEO electrolyte is $60^{\circ}C$. By adding propylene carbonate and ethylene carbonate to $PEO-LiClO_4$ electrolyte, its conductivity was higher than $PEO-LiClO_4$ without those. Also $PEO_8LiClO_4$ electrolyte remains static up to 4.5V vs. $Li/Li^+$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.12
• /
• pp.894-898
• /
• 2013

Zinc oxide(ZnO) was sputtered on various glass and flexible substrates such as polyethylene terephthalate(PET) and polycarbonate(PC). A Q-switched $Nd:YVO_4$ laser with a wavelength of 1,064 nm was used for the direct etching of ZnO films. It was possible to obtain laser etched line patterns on the ZnO films on PC substrate at some specific laser beam conditions. In the flexible substrates, more thermal energy of laser beam is expected to be spreaded for the etching process.

• Journal of Pharmaceutical Investigation
• /
• v.17 no.2
• /
• pp.75-78
• /
• 1987

The release rate of heparin from monolithic devices composed of raffinose, ${\beta}-cyclodextrin$, polyethylene oxide (Mw 20,000, PEO), and hydrophobic polyether urethane (biomer) was investigated. Water soluble raffinose, ${\beta}-cyclodextrin$, and PEO blended into the biomer provided a controlled release of heparin. The release rate of heparin could be controlled by the content of raffinose, ${\beta}-cyclodextrin$, and PEO in the devices. The mechanism of release rate increased by the raffinose, ${\beta}-cyclodextrin$, and PEO may result from the formation of channels and pores in the biomer matrices following the swelling and the change in the physical structure of polymer net work. Hydrophobic polyurethane containing raffinose, ${\beta}-cyclodextrin$, and PEO can provide a hydrophilic antithrombogenic material for prolonged release of heparin.

• Proceedings of the KOSOMBE Conference
• /
• v.1990 no.11
• /
• pp.61-63
• /
• 1990

To develop better blood compatibility of commercial polyurethane(PU), PU surface was chemically modified wi th a hydrophobic perfluorocarhon or a hydrophilic polyethylene oxide(PEO) and/or sulfonated groups, respectively. The water contact angle of modified PUs varied from $110^{\circ}$ to $0^{\circ}$. All the modified PUs were more blood compatible than untreated PU. In particular, PEO-sulfonate grafted PUs showed a very enhanced antithrombogenicity due to the synergistic effect of PEO and $SO_3$ groups. Therefore more hydrophobic and hydrophilic PU surfaces are promising for improving the blood compatibility.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1869-1874
• /
• 2003

Polymeric fibers with nanometer-scale diameters are produced by electrospinning. When the electrical forces at the surface of a polymer solution or melt overcome the surface tension then electrospinning occurs. Polyethylene oxide (PEO), Polycarbonate have been electrospun in our laboratory. Electrospun fibers are observed by optical microscopy or scanning electron microscopy. The average diameters of the electrospun fibers range from 300 nm to 30 nm when the electric field strength increasing from 1 kV/cm to 3 kV/cm. The average diameters of the electrospun fibers range from 200 nm to 30 nm when the concentration decreasing from 10 wt% to 4 wt%.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1685-1687
• /
• 1996

Recently, conducting polymer has been much attracted as novel materials because of its electronic behavior and functional application by doping process. In this paper, we electrochemically synthesized polyaniline films under potential sweep conditions, which exhibit high electric conductivity about 200 S/cm. Specific energy of 600 Wh/kg and Ah efficiency 98% were achieved during the charge/discharge cycling using liquid electrolyte system. On the other hand, consequences of the cycling were 260 Wh/kg and 95% Ah efficiency using polyethylene oxide(PEO) based solid-state electrolyte system.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.05a
• /
• pp.186-186
• /
• 2009

RF 부가형 DC 마그네트론 스퍼터링 공정을 이용하여 상온에서 Indium tin oxide (ITO) 박막을 PET (polyethylene terephthalate) 기판 위에 증착하였다. 전체 파워는 70W로 유지하고 RF/ (DC+RF) 파워율은 0 %에서 100 %까지 20% 비율로 증가시켰다. 50 %의 RF/(RF+DC) 파워율에 의해 증착된 ITO 박막에서 상대적으로 낮은 비저항을 얻을 수 있었으며, bending test에 의한 기계적 내구성 또한 가장 우수하였다.

• Journal of Sensor Science and Technology
• /
• v.25 no.5
• /
• pp.320-325
• /
• 2016

In this paper, we propose an AlGaN/GaN-based extended-gate metal-insulator-semiconductor high electron mobility transistor (MISHEMT)-type biosensor for detecting streptavidin-biotin complexes. We measure the drain current of the fabricated sensor, which varies depending on the antibody-antigen reaction of streptavidin with biotin molecules. To confirm the immobilization of biotin polyethylene glycol (PEG) thiol, we analyze the Au surface of a GaN sample using X-ray photoelectron spectroscopy (XPS). The proposed biosensor shows higher sensitivity than Si-based extended-gate metal oxide semiconductor field effect transistor (MOSFET)-type biosensor. In addition, the proposed AlGaN/GaN-based extended-gate MISHEMT-type biosensor exhibits better long-term stability, compared to the conventional AlGaN/GaN-based MISHEMT-type biosensor.

• 한국항공운항학회:학술대회논문집
• /
• 2015.11a
• /
• pp.13-19
• /
• 2015

본 연구의 목적은 자체 설계 제작한 하이브리드 발사체를 이용하여 대기 중의 미세먼지를 측정하는데 있다. 대기 중의 미세먼지를 측정하기 위한 방법으로는 중량농도법을 이용하였으며, 미세먼지 측정을 위한 포집장치를 자체 제작하였다. 엔진은 5port의 HDPE(High Density Polyethylene)를 연료 그레인으로 사용하였고 $LN_2O$(Liquefied Nitrous Oxide)를 산화제로 사용하였다. 압력, 가속도, GPS 등을 수집하며, 하이브리드 발사체의 동체는 FRP(Fiberglass Reinforced Plastics)로 제작한다. 전체 비행시간은 총 95초로 예상되며. 연소시간은 3초, 고도는 800 m 이다.