• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.06a
• /
• pp.548-551
• /
• 2007

Organic field-effect transistors (OFETs) are of interest for use in widely area electronic applications. We fabricated a copper phthalocyanine (CuPc) based field-effect transistor with different substrate temperature. The CuPc FET device was made a top-contact type and the substrate temperature was room temperature and $150^{\circ}C$. The CuPc thickness was 40nm, and the channel length was $50{\mu}m$, channel width was 3mm. We observed a typical current-voltage (I-V) characteristics in CuPc FET.

• Microbiology and Biotechnology Letters
• /
• v.34 no.4
• /
• pp.357-362
• /
• 2006

A growth inhibition assay using Chlorella sp. AG 10002 based on the OECD 201 standard test procedure was applied to the toxicity testing of endosulfan and its reported metabolites. Comparison of dry cell weight, optical density (OD) at 680 nm, and chlorophyll a concentration indicated that optical density at 680 nm of culture broth is convenient, rapid, and accurate method for cell growth. In this microalgae system, the $IC_{50}$ values of endosulfan, endosulfan sulfate, endosulfan lactone, and endosulfan ether were determined as 9.45, 18.8, 18.2 and 37.5 mg/L, respectively. In a while, endosulfan diol did not show a significant toxicity up to 50 mg/L. Since endosulfan is liable at acidic or alkaline conditions, treatment of endosulfan in pH 3, 4, and 11 for 3 days resulted in reduced toxicity, as expected. These results suggested that the microalgae system is useful to evaluate various toxic chemicals and provide a new notion for bioremediation of endosulfan in aqueous systems.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.12A
• /
• pp.1177-1181
• /
• 2006

In this paper, we proposed the new wavelength tunable filter for wide tunability of fiber ring laser. The proposed filter consists of the cascaded connection of Fiber Reflection Mach-Zehnder Interferometer and Sagnac filter or of hybrid filter and fiber Reflection Mach-Zehnder Interferometer. The simulation shows that the continuous tunable range of 50nm can be obtained and that more stable single mode operation of ring laser can be expected due to narrow FWHM. of filter spectrum.

• Proceedings of the SCSK Conference
• /
• 2003.09a
• /
• pp.258-267
• /
• 2003

Recently inside nano liposome particles or nano-emulsions which contain tough-melting physiology activity materials or the coefficient of low organism utilization promote the coefficient of organism utilization, so this part has been studied a lot because they can absorb selectly cosmetics, specially physiology activity materials, into the skin. Also, in particle size, cells interstitial lipid interval are 30~50nm, so nano-emulsions that the size is similar to 30~50 nm are made to study for absorbing quickly into the skin. And transparent skin which contains oils in common skin lotion dosage form has become the center of public interest. The used nano-emulsions in this study were unsaturated lecithin/co-surfactant! ethanol/ oil / water. And polysorbate 20/ polysorbate 80/ Dicetyl phosphate/hydrogenated .caster oil/ isoceteth-20/SLS were used in co-surfactant. The used oils were cyclomethicone and caprylic/capric triglyceride. The manufacturing process was that microfluidizer was fixed in 1000bar and transit times were changed from 1 to 10 times. From transparency and particle size, the transparency sequence was SLS> polysorbate 20= polysorbate 80> isoceteth-20> dicetyl phosphate >hydrogenated caster oil and the particle size was small. Specially cyclomethicone nano-emulsions, when we made unsaturated lecithin /SLS /ethanol/water/cyclomethicone, cyclomethicone 5％ was good for transparency. And 20％ of this was used for making transparent skin toner in common skin dosage form.

• Journal of the Korean Magnetics Society
• /
• v.3 no.3
• /
• pp.215-220
• /
• 1993

Microstructural dependence of magnetic property of RF/DC sputtered $Co_{69.0}Ni_{18.5}Cr_{12.5}/Cr$ double layer thin film was studied. Grain size was found to be decreased with substrate temperature in the range of $100-200^{\circ}C$ and Cr underlayer thickness(from $500\;{\AA}-2000\;{\AA}$). The peaks (200) and (1120) of X-ray diffraction patterns were evidently grown with the substrate temperature for the Cr underlayer and magnetic layer, respectively. The CoNiCr magnetic layer was found to be well epitaxialy grown on Cr underlayer, and subsequently the coercivity was enhanced.

• Korean Journal of Crystallography
• /
• v.14 no.2
• /
• pp.79-83
• /
• 2003

The microstructure of bulk electrolytic MnO₂ (EMD) was studied using x-ray diffraction and transmission electron microscopy (TEM). The bulk sample showed a typical powder x-ray diffraction pattern of EMD materials. TEM study showed that the structure of EMD is present at two length scales;grains, ∼0.2 ㎛ in diameter, and ∼10 nm crystallites within the grain. The electron beam microdiffraction study revealed that each grain is an assemblage of multiphase with a common crystallographic orientation, and_that ∼50% of the crystallites are Ramsdellite, ∼30% are ε-MnO₂, and ∼15% are Pyrolusite. The ｛1120｝peak located at about 67° in powder XRD pattern as well as a high-resolution electron microscope (HREM) image of (0001) plane support the existence of ε-MnO₂ phase.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.4
• /
• pp.264-269
• /
• 2012

In this study, highly loaded(50 wt%) and very stable Pt/MWCNT catalysts for Polymer Electrolyte Membrane Fuel Cells(PEMFCs) are synthesized in short time scale by microwave assisted polyol method with different microwave irradiation time. The XRD and TEM results show that the Pt size becomes bigger as the microwave irradiation time increases. The mean Pt sizes of fabricated catalysts are 4.1, 4.9 and 8.5 nm when the microwave are irradiated for 10, 20 and 30 min, respectively. When compared with Pt catalyst made by conventional polyol method, it shows better long term durability due to the better Pt dispersion on the MWCNT surface.

• Journal of Electrochemical Science and Technology
• /
• v.2 no.2
• /
• pp.103-109
• /
• 2011

Nanocrystalline $LiFePO_4$ powders were prepared at 660-$670^{\circ}C$ in an Ar atmosphere using two different synthetic routes, solid-state and sol-gel. Both materials showed well-developed XRD patterns without any impurity peaks. Particles composed in the range of 200-300 nm from the solid-state method, and 50-100 nm from the sol-gel method, were confirmed through scanning electron microscopy and dynamic light scattering. The $LiFePO_4$ obtained by the sol-gel method offered a high discharge capacity (153 mAh/g) and stable discharge behavior, even at elevated temperatures (50 and $60^{\circ}C$), whereas poor electrochemical performance was observed from the solid-state method. Rate capability studies for sol gel-derived $LiFePO_4$ ranged from 0.2 to 30 C, which revealed excellent retention over 70 cycles with a 99.9% capacity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.298-299
• /
• 2008

Images of deposited layers of organic light-emitting diodes were observed by scanning-electron microscope (SEM). We were able to see a clear cross-sectional view of deposited layers. The SEM is a type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. A thickness of deposited layer measured by thickness monitor is close to a real value measured by a-step surface profiler within 5%. We were able to see a formation of domains of size about 50-100nm from a surface morphology of Al, and pin holes of size about 50nm.

• Journal of Ginseng Research
• /
• v.20 no.1
• /
• pp.54-59
• /
• 1996

Red Ginseng extracts sol'n was sterilized at 85f for 20 mins and/or stored at 4$0^{\circ}C$ for 6 months and centrifuged for 20 mins at 8,500xg in order to investigate the changes in chemical components of supernatants and the properties of precipitates. Contents of crude saponin and ginsenoside-$Rb_1$, -$Rg_1$, -Re were partially decreased during heating and storage. Starch contents were decreased from 26.81% in red ginseng extracts to 17.50-8.81% in supernatants, whereas free sugar contents were increased from 15.50% to 20.29~21.35% by heating and storage. The contents of protein and minerals in supernatants were decreased, but acidic polysaccharides and polyphenol compounds were not changed. pH values of supernatants and precipitates were decreased. The absorbances of brown color precursor and brown pigment in precipitates, detected at 285 nm and 440 nm were remarkably increased. The Overa11 data suggest that precipitates in red ginseng extracts sol'n formed during steilization and storage are provably the brown pigments resulting from Maillard reaction of amino compounds with reducing sugar which could be released from starch and protein matrix and $Cu^+$, $Ca^{2+}$ and $Fe^{3+}$ ions are implicated with the reaction incorporated.