• Journal of Microbiology and Biotechnology
• /
• v.24 no.11
• /
• pp.1516-1524
• /
• 2014

Flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) can utilize a variety of external electron acceptors and also has stricter substrate specificity than any other glucose oxidoreductases, which makes it the ideal diagnostic enzyme in the field of glucose biosensors. A gene coding for a hypothetical protein, similar to glucose oxidase and derived from Aspergillus terreus NIH2624, was overexpressed in Pichia pastoris GS115 under the control of an AOX1 promoter with a level of 260,000 U/l in the culture supernatant after fed-batch cultivation for 84 h. After a three-step purification protocol that included isopropanol precipitation, affinity chromatography, and a second isopropanol precipitation, recombinant FAD-GDH was purified with a recovery of 65%. This is the first time that isopropanol precipitation has been used to concentrate a fermentation supernatant and exchange buffers after affinity chromatography purification. The purified FAD-GDH exhibited a broad and diffuse band between 83 and 150 kDa. The recombinant FAD-GDH was stable across a wide pH range (3.5 to 9.0) with maximum activity at pH 7.5 and $55^{\circ}C$. In addition, it displayed very high thermal stability, with a half-life of 82 min at $60^{\circ}C$. These characteristics indicate that FAD-GDH will be useful in the field of glucose biosensors.

• YAKHAK HOEJI
• /
• v.37 no.2
• /
• pp.129-135
• /
• 1993

Serratia sp. Y-4 was isolated from soil. Many characteristics of the strain and optimum cultivation condition for protease production were investigated.,The protease from Serratia sp. Y-4 was purified and studied for the properties of the enzyme. The isolated strain was identified to the genus Serratia. The strain was cultivated in 1%-casein, 0.5%-Na$_{3}$PO$_{4}$.7H$_{2}$O, 0.1%-NaCl, 0.05%-KCI, 0.02%-MgSO$_{4}$.7H$_{2}$O, 0.02%-CaCl$_{2}$.2H$_{2}$O, 0.02%-ZnSO$_{4}$.7H$_{2}$O, 0.02%-MnCl$_{2}$.4H$_{2}$O and 0.5%-soy bean oil at pH 7.0 for 35 hrs. The enzyme was purified about 5.89 fold from the culture broth with 31.1% recovery and 19,613 u/mg through ultrafiltration, ammonium sulfate, DEAE-sephacel and Superose-12 chromatography. The purified enzyme was identified as one band by isoelectric focusing, SDS- and native-PAGE. It has maxium activity at $37^{\circ}C$ and pH 9.0. Molecular weight of it is approx. 50 kD and pl is about 6.70. Its Km value for casein was 20 mg/ml. 5 mM-EDTA, 5mM-SDS, Ag$^{+1}$, Cu$^{+2}$, Hg$^{+2}$ and Pb$^{+2}$ inhibited the enzyme.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.2
• /
• pp.145-150
• /
• 2016

In this paper, we proposes a DTV indoor receiving antenna with a gap sleeve monopole structure. The proposed antenna uses a basic structure of a sleeve monopole and gap sleeve. To optimize antenna, we have adjusted the gap between monopole and sleeve, the gap between sleeve and ground. In order to confirm the property of antenna parameters, it was used a commercial software, HFSS. For the antenna fabrication, a FR4 dielectric substrate which has a dielectric constant of 4.7 was used. The size of the antenna was $213mm{\times}40mm{\times}1.6mm$. Frequency band of the fabricated antenna was 432MHz ~ 827MHz, and the bandwidth was 395MHz. The maximum gain of the antenna was 2.19dBi. Consequently, it was confirmed the possibility of practical application of the DTV indoor receiving antenna with a gap sleeve monopole structure.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.16 no.6
• /
• pp.235-239
• /
• 2006

ZnO-doped near-stoichiometric $LiNbO_3$ single crystals of $0.8{\sim}1.0mm$ diameter and $30{\sim}35mm$ length were grown by the micro-pulling down (U-PD) method. The structure of the grown crystals was confirmed by powder x-ray diffraction (XRD) patterns. Electron probe micro analysis (EPMA) showed that Zn ions were homogeneously incorporated In grown crystals. The threshold in ZnO doping level was confirmed that an abrupt change in the features of $OH^-$ absorption band as doping level reaching about 2 mol%.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.405-407
• /
• 2015

We describe a survey of quasars in the early universe, beyond z ~ 5, which is one of the main science goals of the Infrared Medium-deep Survey (IMS) conducted by the Center for the Exploration of the Origin of the Universe (CEOU). We use multi-wavelength archival data from SDSS, CFHTLS, UKIDSS, WISE, and SWIRE, which provide deep images over wide areas suitable for searching for high redshift quasars. In addition, we carried out a J-band imaging survey at the United Kingdom InfraRed Telescope with a depth of ~23 AB mag and survey area of ${\sim}120deg^2$, which makes IMS a suitable survey for finding faint, high redshift quasars at z ~ 7. In addition, for the quasar candidates at z ~ 5.5, we are conducting observations with the Camera for QUasars in EArly uNiverse (CQUEAN) on the 2.1m telescope at McDonald Observatory, which has a custom-designed filter set installed to enhance the efficiency of selecting robust quasar candidate samples in this redshift range. We used various color-color diagrams suitable for the specific redshift ranges, which can reduce contaminating sources such as M/L/T dwarfs, low redshift galaxies, and instrumental defects. The high redshift quasars we are confirming can provide us with clues to the growth of supermassive black holes since z ~ 7. By expanding the quasar sample at 5 < z < 7, the final stage of the hydrogen reionization in the intergalactic medium (IGM) can also be fully understood. Moreover, we can make useful constraints on the quasar luminosity function to study the contribution of quasars to the IGM reionization.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.517-519
• /
• 2015

A large-scale neutral hydrogen ($H\small{I}$) ring serendipitously found in the Leo I galaxy group is 200 kpc in diameter with $M_{H\small{I}}{\sim}1.67{\times}10^9M_{\odot}$, unique in size in the Local Universe. It is still under debate where this $H\small{I}$ ring originated - whether it has formed out of the gas remaining after the formation of a galaxy group (primordial origin) or been stripped during galaxy-galaxy interactions (tidal origin). We are investigating the optical and $H\small{I}$ gas properties of the dwarf galaxies located within the gas ring in order to probe its formation mechanism. In this work, we present the photometric properties of the dwarfs inside the ring using the CFHT MegaCam $u^{\ast}$, $g^{\prime}$, $r^{\prime}$ and $i^{\prime}$-band data. We discuss the origin of the gas ring based on the stellar age and metal abundance of dwarf galaxies contained within it.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.141.1-141.1
• /
• 2012

CIBER (Cosmic Infrared Background ExpeRiment) is a sounding-rocket borne experiment which is designed to find the evidence of the First stars (Pop.III stars) in the universe. They are expected to be formed between the recombination era at z ~ 1100 and the most distant quasar (z ~ 8). They have never been directly detected due to its faintness so far, but can be observed as a background radiation at around $1{\mu}m$ which is called the Cosmic Near-Infrared Background (CNB). The CIBER is successfully launched on July 10, 2010 at White Sands Missile Range, New Mexico, USA. It consists of three kinds of instruments. One of them is a LRS (Low Resolution Spectrometer) which is a refractive telescope of 5.5 cm aperture with spectral resolution of 20 ~ 30 and wavelength coverage of 0.7 to $2.0{\mu}m$ to measure the spectrum of the CNB. Since LRS detects not only CNB but also stellar components, we can study their spectral features with the broad band advantage especially at around $1{\mu}m$ which is difficult at ground observations because of the atmospheric absorption by water vapor. I identified around 300 stars from observed six fields. If we can classify their spectral types with SED fitting, we can study their physical conditions of the stellar atmosphere as well as making a stellar catalogue of continuous stellar spectrum.

• Korean Journal of Oriental Medicine
• /
• v.17 no.3
• /
• pp.97-104
• /
• 2011

Objectives : In this paper, we proposed a method for selecting reliable variables from various vocal features such as frequency derivative features, frequency band ratios, intensities of 5 vowels and an intensity of a sentence, since some features are sensitive to the variation of a subject's utterance. Methods : To obtain the reliable voice variables, the coefficient of variation (CV) was used as the index to evaluate the level of reliability. Since the distributions of a few features are not Gaussian, but are instead skewed to the right or left, we transformed the features by taking the log or square root. Moreover, the definition of the variables that are suitable to represent the vocal property was explained and analyzed. Results : At first, we recorded the vowels and the sentence five times both in the morning and afternoon of the same day, totally ten recordings from each of six subjects (three males and three females). We then analyzed the CVs of each subject's voice to obtain the stable features with a sufficient repeatability. The features having less than 20% CVs for all six subjects were selected. As a result, 92 stable variables from the 222 features were extracted, which included all the transformed variables. Conclusions : Voice can be widely used to classify the four constitution types and to recognize one's health condition from extracting meaningful features as physical quantity in traditional Korean medicine or Western medicine. Therefore, stable voice variables can be useful in the u-Healthcare system of personalized medicine and for improving diagnostic accuracy.

• Transactions on Electrical and Electronic Materials
• /
• v.5 no.1
• /
• pp.1-6
• /
• 2004

Zinc sulfide is a semiconductor with wide band gap and high refractive index and hence promising material to be used as ARC on commercial silicon solar cells. Uniform deposition of zinc sulfide (ZnS) by using chemical bath deposition (CBD) method over a large area of silicon surface is an emerging field of research because ZnS film can be used as a low cost antireflection coating (ARC). The main problem of the CBD bath process is the huge amount of precipitation that occurs during heterogeneous reaction leading to hamper the rate of deposition as well as uniformity and chemical stoichiometry of deposited film. Molar concentration of thiorea plays an important role in varying the percentage of reflectance and refractive index of as-deposited CBD ZnS film. Desirable rate of film deposition (19.6 ${\AA}$ / min), film uniformity (Std. dev. < 1.8), high value of refractive index (2.35), low reflectance (0.655) have been achieved with proper optimization of ZnS bath. Decrease in refractive index of CBD ZnS film due to high temperature treatment in air ambiance has been pointed out in this paper. Solar cells of conversion efficiency 13.8 ％ have been successfully achieved with a large area (103 mm ${\times}$ 103 mm) mono-crystalline silicon wafers by using CBD ZnS antireflection coating in this modified approach.

• Journal of Dairy Science and Biotechnology
• /
• v.21 no.2
• /
• pp.114-119
• /
• 2003

Acidocin 4A produced by Lactobacillus acidophilus GP4A was purified to homogeneity by ammonium sulfate precipitation and sequential chromatographies containing Octyl sepharose CL-4B column, $C_{18}$ Sep-Pak Cartridge, $C_{18}$ RP HPLC and HPLC gel filtration. Tricine SDS-PACE resulted in a single band with estimated molecular mass of 4.1 kDa corresponding to the polypeptide weight marker. Electron microscopy of acidocin-treated indicator cells(L. delbrueckii subsp. lactis ATCC 4797) confirmed that acidocin 4A presented bacteriolytic effect, resulting in cell lysis. Curing trial using ethidium bromide (EtBr) was carried out to examine whether acidocin 4A determinant was encoded either by chromosome or on plasmid. The plasmid designated as pLA4A, being about 20 kb in size, was responsible for acidocin 4A production and immunity to host cells.