• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.129-129
• /
• 2010

The conjugated oligomers with rigid and fused-ring structures are of interest for the solution-processable organic thin film transistors (OTFTs) due to their well defined structure and high purity. In this study, alkyl substituted benzothiophene based oligomers were synthesized by a novel route, the key point of which is the acid-induced intermolecular cyclization reaction of aromatic methyl sulfoxides, and were confirmed by $^1H$-NMR and FT-IR studies. The obtained oligomers showed the good solubility in common organic solvents such as hexane, chloroform, and dimethylchloride at room-temperature, which is due to the introduced alkyl chain. The physical and optical properties of the oligomers were studied using differential scanning scalorimetry (DSC), cyclic-voltammetry (CV), UV-visible and PL spectra studies. Solution processed OTFT device based on synthesized oligomers show a high hole mobility of up to $0.01\;cm^2V^{-1}s^{-1}$, $I_{on}/I_{off}$ of $10^5$ and threshold voltage of -14V.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.6
• /
• pp.567-574
• /
• 2016

We have analyzed chemical properties of polysiloxane and polysilazane films, respectively, as sealing materials for electrostatic chuck (ESC) and have investigated the possibility of polysilazane as an alternative sealant to polysiloxane. It has been revealed that Si-O with organic bonding ($Si-CH_3$) existed in polysiloxane films compared to only pure Si-O bonding in polysilazane films. The sealing property of polysilazane has been found outstanding even in a short time of application. In the polysiloxane films containing $H_2O$, pin holes have been found possibly due to $CO_2$ gas evolution, and low adhesion with Si substrate has been observed after heat stress test in connection with the existence of organic bonding. After acid resistance test in 0.5 vol.% HF, 68 wt.% $HNO_3$, and 37 wt.% HCl solution, polyilazane films have shown a longer survival times. Compared to the conventional polysiloxane sealant, polysilazane is expected as a new sealing material because of good thermal and chemical stability.

• Proceedings of the KIEE Conference
• /
• 1998.07d
• /
• pp.1503-1505
• /
• 1998

Stearic acid was deposited on surface of 9[MHz], AT-cut quartz crystal microbalance as gas sensing material using Langmuir-Blodgett(LB) technique. We measured gas response between deposited LB films and organic gas for various temperature($0{\sim}80^{\circ}C$). The resonant frequency changed due to absorbance of organic gas such as methanol and butanol gas at room temperature. However, the resonant frequency not responded to methanol gas at temperature above melting point of deposited LB films.

• Proceedings of the Korean Society of Organic Agriculture Conference
• /
• 2009.12a
• /
• pp.314-314
• /
• 2009

The effects of mixtures of each of rice hull charcoal and wood charcoal with pyroligneous acid on the cultivation and antioxidant activities of rice were investigated. Results of the total phenolic compounds, DPPH radical electron-donating ability and xanthine oxidase stress activity analyses revealed that the environment-friendly materials increased the total antioxidant capacity in rice. In the case of palatability of rice, total amylose blue value and starch-I2color reaction analyses, data showed that environment-friendly materials generally decreased the amylose content of rice. Also, the environment-friendly materials improved the rice endosperm quality.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.4
• /
• pp.431-435
• /
• 1999

An organic precipitate flotation of Cd(Ⅱ) and Pb(Ⅱ) was investigated by the coprecipitation with lanthanum 8-hydroxyquinolinate. Trace amounts of Cd(Ⅱ) and Pb(Ⅱ) with a significantly large amount of La(Ⅲ) were simultaneously precipitated in a 1,000 mL sample solution with the ethanolic 8-hydroxyquinoline solution. The pH was adjusted to 9.0 with 2 M ammonia solution. The precipitates were floated with the aid of tiny nitrogen bubbles and supported by the stable foam layer of sodium lauryl sulfate. The floats were collected on the fritted glass filter by a suction. The material collected was dissolved with 5.0 mL of ethanol and 1.5 mL of concentrated nitric acid, and then diluted to 25.0 mL with a deionized water. The analytes were determined by a flame atomic absorption spectrophotometry. The recoveries of the analytes spiked in the sample were 94.8% for Pb(Ⅱ) and 92.0% for Cd(Ⅱ). This flotation technique is simple and rapid, and also applicable to the determination of trace Cd(Ⅱ) and Pb(Ⅱ) at lew ppb levels.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.14 no.2
• /
• pp.112-120
• /
• 2006

For the conversion of food waste into a good recycling material such as animal feed without antibiotics, thirteen lactic acid bacteria, which can be used as good probiotics for animal feed, were isolated from the intestine and feces in pigs. All isolates showed strong tolerance to high salt (4% of NaCl), acid(pH4.0), and bile juice (0.8% of oxgall). The growth rate was best at $37^{\circ}C$ in all strains. Among the isolates, Lactobacillus plantarum CJY-22, L. brevis CJY-42, L. arizonensis CJY-3, and Pediococcus sp. CJY-41 showed higher and broader spectrum of antimicrobial activities against six different pathogens such as Salmonella, typhimurium. L. plantarum CJY-22 has also grown well at $25^{\circ}C$, making this strain as an appropriate candidate for the fermentation of food waste at room temperature, thus conducting the fermentation process cost-effectively.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.3 no.2
• /
• pp.92-99
• /
• 1983

Experiment were conducted to study effect of pre-wilting on the quality of silage. Herbage samples were taken on November 11, 1981. Italian ryegrass and rye plant at grazing stage were taken and wilted to adjust their dry matter contents to the range of 15.8 to 53.2% and ensiled in order to evaluate the effect of pre-wilting on the chemical composition and nutrient loss of silage. Both prewilted and unwilted grass material were ensiled in small polyetylene film bag and stored under room temperature. 1. The formation of total acid decreased by increasing DM content, however, lactic acid content of the total organic acid increased. 2. In the silage, the loss of DM declined as DM content increased. 3. The quality of silage estimated by organic acid constituent was improved as DM content in the herbage increased. 4. The production of $NH_3-N$ decreased by increasing degree of prewilting. 5. In vitro dry matter digestibility was not affected by prewilting.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.8
• /
• pp.581-586
• /
• 1998

This paper describes athermally stimulated displacement current (TSDC) of arachidic acid(AA) and polyamic acid alkylamine salts(PAAS) Langmuir-Blodgett(LB) films, which is a precursor of polyimide(PI). The TSDC measurements of AA LB film were performed from temperature to about 11$0^{\circ}C$ at a rate of 0.2$^{\circ}C$/ｓ inside a vacuum chamber for a reference. And the TSDC measurements PAAS LB film were performed from room temperature to about 25$0^{\circ}C$ and temperature was increased at the same rate as that of AA LB film. They show that there are TSDC peaks at about 7$0^{\circ}C$ in the arachidic acid LB films, and at about 7$0^{\circ}C$ and 16$0^{\circ}C$ in the PAAs LB films. Results of these measurements indicate the one small peak at 7$0^{\circ}C$ is resulted from a softening of the alkyl group and the large peak at 16$0^{\circ}C$ is possibly due to dipole of C-O group in the PASS molecule. We have calculated the vertical component of the AA and PAAs L film out of the TSDC curves. It shows that the dipole moment of the AA LB film is about 70-mD at 7$0^{\circ}C$. And the dipole moment of PAAS LB film is about 040mD at 7$0^{\circ}C$ and about 200mD at 16$0^{\circ}C$ in the first measurement of TSDC. In the second measurement of TSDC of PASS LB film after cooling down to room temperature, the TSDC peaks are almost disappeared.

• Korean Journal of Materials Research
• /
• v.24 no.6
• /
• pp.285-292
• /
• 2014

Commercial activated-carbon used as the electrode material of an electric double-layer capacitor (EDLC) was posttreated with various acids and alkalis to increase its capacitance. The carbon samples prepared were then heat-treated in order to control the amount of acidic functional groups formed by the acid treatments. Coin-type EDLC cells with two symmetric carbon electrodes were assembled using the prepared carbon materials and an organic electrolyte. The electrochemical performance of the EDLC was measured by galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. Among the various activated carbons, the carbon electrodes (CSsb800) prepared by the treatments of coconutshell-based carbon activated with NaOH and $H_3BO_5$, and then heat treated at $800^{\circ}C$ under a flow of nitrogen gas, showed relatively good electrochemical performance. Although the specific-surface-area of the carbon-electrode material ($1,096m^2/g$) was less than that of pristine activated-carbon ($1,122m^2/g$), the meso-pore volume increased after the combined chemical and heat treatments. The specific capacitance of the EDLC increased from 59.6 to 74.8 F/g (26%) after those post treatments. The equivalent series resistance of EDLC using CSsb800 as electrode was much lower than that of EDLC using pristine activated carbon. Therefore, CSsb800 exhibited superior electrochemical performance at high scan rates due to its low internal resistance.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.281-281
• /
• 2010

Very low refractive index (<1.4) materials have been proved to be the key factor improving the performance of various optical components, such as reflectors, filters, photonic crystals, LEDs, and solar cell. Highly porous SiO2 are logically designed for ultralow refractive index materials because of the direct relation between porosity and index of refraction. Among them, ordered macroporous SiO2 is of potential material since their theoretically low refractive index ~1.10. However, in the conventional synthesis of ordered macroporous SiO2, the time required for the crystallization of organic nanoparticles, such as polystyrene (PS), from colloidal solution into well ordered template is typical long (several days for 1 cm substrate) due to the low interaction between particles and particle - substrate. In this study, polystyrene - polyacrylic acid (PS-AA) nanoparticles synthesized by miniemulsion polymerization method have hydrophilic polyacrylic acid tails on the surface of particles which increase the interaction between particle and with substrate giving rise to the formation of PS-AA film by simply spin - coating method. Less ordered with controlled thickness films of PS-AA on silicon wafer were successfully fabricated by changing the spinning speed or concentration of colloidal solution, as confirmed by FE-SEM. Based on these template films, a series of macroporous SiO2 films whose thicknesses varied from 300nm to ~1000nm were fabricated either by conventional sol - gel infiltration or gas phase deposition followed by thermal removal of organic template. Formations of SiO2 films consist of interconnected air balls with size ~100 nm were confirmed by FE-SEM and TEM. These highly porous SiO2 show very low refractive indices (<1.18) over a wide range of wavelength (from 200 to 1000nm) as shown by SE measurement. Refraction indices of SiO2 films at 633nm reported here are of ~1.10 which, to our best knowledge, are among the lowest values having been announced.