• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.4
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• pp.563-569
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• 1995

Myrosinase from Korean cabbage(Bogdoli) was purified and its enzymatic properties were investigated. Myrosinase from the Korean cabbage was purified by DEAE Bio-Gel Sepharose, Concanavalin-A, and Mono-Q column chromatography and exhibited a 55KD molecular weight with a single band on the gel of SDS-PAGE. The enzyme was purified about 21-fold compared to its crude enzyme and a specific activity of purified enzyme was 15, 120units/mg. Optimum pH of the myrosinase was 7.0 in both phosphate and Tris-HCl buffer solutions, the enzyme was stable at pH 6.5~7.0. Optimum temperature of enzyme was 37~38$^{\circ}C$. The enzyme activity was significantly inhibited by Cu2+ and Hg2+, but enhanced by ascorbic acid, resulting in a maximum activity at 1mM ascorbic acid. Among the ascorbic acid analogues, dehydro-ascorbic acid did not affect, whereas others showed a little effect on the enzyme activity, but less than ascorbic acid itself. Reducing agents such as 2-mercaptoethanol and dithiothreitol had no effect on the enzyme activity, but the enzyme activity was enhanced when 2-mercaptoethanol was mixed with ascorbic acid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.4
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• pp.570-577
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• 1995

Aspergillus sp. SB-2704 was selected for its strong polygalacturonase activity among various strain of mold found in soil. It was found that production of polygalacturonase reached to maximum when the wheat bran medium containing 1% polypepton, 1% glucose, and 0.2% FeSO4 were cultured for 3 days at 35$^{\circ}C$. Polygalacturonase was purified 20.90 fold from Aspergillus SB-2704. The purification procedures include ammonium sulfate treatment, gel filtration on Sephdex G-150 and DEAE-cellulose ion exchange chromatography. Yield of the enzyme purification was 4.34%. Purified enzyme was confirmed as a single band by the polyacrylamide gel electrophoresis. When the purified enzyme was applied to SDS-polyacrylamide gel electrophoresis, the molecular weight was estimated to be 36,000. The optimum pH for the enzyme activity was 5.5 and optimum temperature was 5$0^{\circ}C$. The enzyme is stable in acidic condition. The activity of purified enzyme was inhibited by Pb2+, Hg2+ and Ba2+, whereas activated by Cu2+, Mn2+, Mg2+ and Fe2+. The activity of polygalacturonase was inhibited by the treament wit maleic anhydride, iodine, and EDTA. The result indicate the possible involvement of histidine and metal ion at active site.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.586-590
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• 2006

Dendrimers represent a new class of synthetic macromoleculcs characterized by a regularly branched treelike structure. Multiple branching yields a large number of chain ends that distinguish dendrimers from conventional star-like polymers and microgels. The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and 8A5H were performed. The 8A5H organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.636-641
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• 2000

The purpose of this study is assessing the characteristics of surface aging and recovery of hydrophobicity for silicone rubber which takes a great interest as outdoor insulation recently subjected to the combined stressed of salt fog and AC power. The methods for assessing are contact angle ATR-FRIR, AFM and XRD. In addition salt fog method is adopted as the artificial contamination experiment and AC power is applied 24 hour on and 24 hour off repeatedly for 5 cycles. The results suggest that degraded surface was more rough than virgin but was restored water repellency through the off cycle. It was due to not only the formation of fractal surface but also maintenance of hydrophobic surface by diffusion of low molecular oil. Although surface recovers initial hydropohbicity there are possibilities of decreasing electrical performance due to irreversable changes such as depolymerization of surface and loss of filler particles. This fact is confirmed by surface conductivity measurement showing that the degradation is significant and the recovery of hydrophobicity is imperfect as the energized cycle increases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.518-520
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• 1997

Recently, thiophene oligomer with short chain lengths has received much attention as model compounds for facilitating better understanding of electronic and optical properties of polymers, because oligomer is well-defined chemical systems and its conjugation chain length can be exactly controlled. Moreover, organic this films based on conjugated thiophene oligomer have potential for application to electronic and optoelectronic devices such as MISFETs(metal-insulator-semiconductor field-effect transistors) and LEDs(light-emitting diodes). However, there is little knowledge on electronic and structural properties of linear-conjugated oligothiophenes in solid states, compared with those in solutions. $\alpha$-sexithienyl($\alpha$-6T) thin-films were deposited by OMBD(Organic Molecular Beam Deposition) technique, where the $\alpha$-6T was synthesized and purified by the sublimation method. The $\alpha$-6T films were deposited under various conditions. The effects of deposition rate, substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecules in the $\alpha$-6T film deposited at a low deposition rate under a high vacuum were aligned almost perpendicular to the substrate. The $\alpha$-6T films deposited at an elevated substrate temperature showed higher conductivity than the film deposited at room temperature. Electrical characterization of these films will be also executed by using four-point probe measurement technique.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1408-1409
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• 2006

In this paper, poly methyl methacrylate thin films were deposited on a ITO glass substrate using a plasma polymerization technique. In order to investigate the influence of the plasma coupling method and plasma conditions on the plasma polymerized poly methyl methacrylate (ppMMA) thin film properties, inductively coupled (ICP) and capacitively coupled plasma (CCP) were used to generate the plasma and the plasma parameters were varied. Molecular structures of the ppMMAs were investigated using a Fourier Transform Infrared (FT-IR) spectroscopy. Dielectric constants of the ppMMA thin films were investigated using a impedance analyzer (HP4192A, LF Impedance Analyzer). Current-Voltage (I-V) characteristics of the ppMMA thin films were investigated using a source measurement unit (SMU: Keithley 2400). Relationship between the plasma coupling technique/process parameter and ppMMA thin films properties were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04a
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• pp.31-34
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• 2004

During the last 20 years organic semiconductors have attracted considerable attention due to their interesting physical properties followed by various technological applications in the area of electronics and opto-electronics. It has been a long time since organic solar cells were expected as a low-cost energy-conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar cell devices based on zinc-phthalocyanine(ZnPc) as donor(D) and fullerine$(C_{60})$ as electron acceptor(A) with doped charge transport layers, $Alq_3$ as an electron transport or injection layer. We observed the photovoltaic characteristics of the solar celt devices using the Xe lamp as a light source.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1890-1892
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• 2005

Recently, high luminance and high efficiency were realized in OLEDs with multilayer structure including emitting materials such as metal-chelate complexes. New luminescent materials, [2- (2-hydroxyphenyl)-quinoline] (Zn(HPB)q), [(1,10-phenanthroline)- (8-hydroxyquinoline)] Zn(Phen)q was synthesized. Zn-Complexes have low molecular compound and thermal stability. The ionization potential(IP) and electron affinity(EA) of Zn-complexes were measured by cyclic-voltammetry(CV). The fundamental structure of the OLEDs was $ITO/{\alpha}$-NPD/Zn-Complex/Al and then we made device structure rightly in energy band gap. We using Zn(Phen)q as emitting layer and Zn(HPB)q as electron transport layer. We measured current density-voltage, luminance-voltage characteristics.

• Journal of Sensor Science and Technology
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• v.17 no.5
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• pp.329-337
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• 2008

Simple, small and portable oxygen sensors were fabricated by tape casting technique. Yttria stabilized zirconia containing cordierite ceramics (YSZC) were used as a porous diffused layer of oxygen in pumping cell. Yttria stabilized zirconia (YSZ) solid electrolyte, YSZC porous diffusion layer and heater-patterned ceramic sheets were prepared by co- firing method. Limit current characteristics and the linear relationship of current to oxygen concentration were observed. Viscosity variation of the slurries both YSZ and YSZC showed a similar behavior, but micro pores in the fired sheet were increased with increasing of the cordierite amount. Molecular diffusion was dominated due to the formation of large pores in porous diffusion layer. The plateau range of limit current in porous-type oxygen sensor was narrow than the one of aperture-type oxygen sensor. However limit current curve was appeared in porous-type oxygen sensor even at the lower applied voltage. The plateau range of limit-current was widen as increasing the thickness of porous diffusion layer of the YSZ containing cordierite. Measuring temperature of $600{\sim}650^{\circ}C$ was recommended for limit-current oxygen sensor. Porous diffusion layer-type oxygen sensor showed faster response than the aperture-type one and was stable up to 30 days running without any crack at interface between the layers.

• Genomics & Informatics
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• v.11 no.4
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• pp.230-238
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• 2013

Many other human species appeared in evolution in the last 6 million years that have not been able to survive to modern times and are broadly known as archaic humans, as opposed to the extant modern humans. It has always been considered fascinating to compare the modern human genome with that of archaic humans to identify modern human-specific sequence variants and figure out those that made modern humans different from their predecessors or cousin species. Neanderthals are the latest humans to become extinct, and many factors made them the best representatives of archaic humans. Even though a number of comparisons have been made sporadically between Neanderthals and modern humans, mostly following a candidate gene approach, the major breakthrough took place with the sequencing of the Neanderthal genome. The initial genome-wide comparison, based on the first draft of the Neanderthal genome, has generated some interesting inferences regarding variations in functional elements that are not shared by the two species and the debated admixture question. However, there are certain other genetic elements that were not included or included at a smaller scale in those studies, and they should be compared comprehensively to better understand the molecular make-up of modern humans and their phenotypic characteristics. Besides briefly discussing the important outcomes of the comparative analyses made so far between modern humans and Neanderthals, we propose that future comparative studies may include retrotransposons, pseudogenes, and conserved non-coding regions, all of which might have played significant roles during the evolution of modern humans.