• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.782-787
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• 2010

Recently the solution-based thin film technology has often been treated in the field of device fabrication owing to easy process and convenience for the development of various semiconductor devices and sensors. We deposited on glass substrate single-walled carbon nanotubes (SWNTs)/silane hybrid thin films by multiple spray-coating which is one of solution-based processes, and examined their electrical response for humidity. Generally silane binders which are often mixed in carbon nanotube (CNT) solution to adhere CNTs to substrate well form easily each own functionalized group on the surface of CNTs after they are hardened by way of the hydrolysis reaction. In this work, we investigated how silane binders (TEOS (tetraethoxy silane), MTMS (methyltrimethoxysilane) and VTMS (vinyltrimethoxysilane)) in CNT thin films make effect to their electrical response on humidity. As the result, we found that the resistance in the samples using TEOS was changed dramatically while it was almost invariant in the samples using MTMS and VTMS for increasing humidity.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1502-1510
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• 2018

Organic solvent-tolerant (OST) enzymes are widely applied in various industries for their activity and stability in organic solvents, for their higher substrate solubility, and for their greater stero-selectivity. However, the criteria for identifying OST enzymes largely remain undefined. In this study, we compared the amino acid composition of 19 OST esterases with that of 19 non OST esterases. OST esterases have increased the ratio of Ala and Arg residues and decreased the ratio of Asn, Ile, Tyr, Lys, and Phe residues. Based on our amino acid composition analysis, we cloned a carboxylesterase (EstSP2) from a psychrophilic bacterium, Sphingomonas glacialis PAMC 26605, and characterized its recombinant protein. EstSP2 is a substrate specific to p-nitrophenyl acetate and hydrolyzed aspirin, with optimal activity at $40^{\circ}C$; at $4^{\circ}C$, the activity is approximately 50% of its maximum. As expected, EstSP2 showed tolerance in up to 40% concentration of polar organic solvents, including dimethyl sulfoxide, methanol, and ethanol. The results of this study suggest that selecting OST esterases based on their amino acid composition could be a novel approach to identifying OST esterases produced from bacterial genomes.

• BMB Reports
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• v.46 no.1
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• pp.37-40
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• 2013

CY-007 and CY-049 pteridine glycosyltransferases (PGTs) that differ in sugar donor specificity to catalyze either glucose or xylose transfer to tetrahydrobiopterin were studied here to uncover the structural determinants necessary for the specificity. The importance of the C-terminal domain and its residues 218 and 258 that are different between the two PGTs was assessed via structure-guided domain swapping or single and dual amino acid substitutions. Catalytic activity and selectivity were altered in all the mutants (2 chimeric and 6 substitution) to accept both UDP-glucose and UDP-xylose. In addition, the wild type activities were improved 1.6-4.2 fold in 4 substitution mutants and activity was observed towards another substrate UDP-N-acetylglucosamine in all the substitution mutants from CY-007 PGT. The results strongly support essential role of the C-terminal domain and the two residues for catalysis as well as sugar donor specificity, bringing insight into the structural features of the PGTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.381.2-381.2
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• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.152-156
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• 2014

Isoquercitrin (IQ), quercetin monoglycoside, is classified as a polyphenol, and a minute quantity of IQ is known to be present in several plants. Recently, it was reported that IQ can be prepared by the partial enzymatic hydrolysis of quercetin diglycoside (rutin, RU). In this paper, the effects of enzyme types, enzyme amounts, and substrate concentrations on the reactivity were investigated using a series of $Pecinex^{TM}$ multi-enzymes. The reaction, when a 8 ml of Ultra Clear to 1 g of RU was applied with the substrate concentration of 1% at $50^{\circ}C$, was found to be optimum, based on the reaction rate and the selectivity to IQ.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.202-206
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• 2009

Flat type catalytic combustible hydrogen sensors were fabricated using platinum micro-heaters and sensing material pastes. The platinum micro-heater was formed on an alumina substrate by sputtering method. The paste for the sensing materials was prepared using ${\gamma}-Al_2O_3$ 30 wt%, $SnO_2$ 35 wt%, and Pd/Pt 30 wt% and coated on the platinum micro-heater. The sensing performances were tested for the prepared sensors with different substrate sizes. The micro catalytic combustible hydrogen sensors showed quick response time, high reliability, and good selectivity against various gases(CO, $C_3H_8,\;CH_4$) at low operating temperature of $156^{\circ}\C$.

• Membrane Journal
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• v.33 no.6
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• pp.377-382
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• 2023

In this study, a PEBAX/PVDF composite membrane was fabricated, and its pervaporation performance was tested in an ethanol/water mixture. In addition, we attempted to improve the pervaporation performance of the composite membrane by forming a ZIF-8 layer on the surface of the PVDF substrate. The thickness of selective layer was optimized by comparing the pervaporation performance depending on the PEBAX thickness. A pervaporation test was performed on the Ethanol/Water mixture. As a result, the composite membrane using PVDF substrate with ZIF-8 layer had a flux of 1.98 kg/m²h and separation factor of 3.88, showing higher values of both permeation flux and selectivity than the composite membrane using bare PVDF substrate.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1269-1274
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• 2014

Monoamine oxidases catalyze the oxidative deamination of dietary amines and amine neurotransmitters, and assist in maintaining the homeostasis of the amine neurotransmitters in the brain. Dysfunctions of these enzymes can cause neurological and behavioral disorders including Parkinson's and Alzheimer's diseases. To understand their physiological roles, efficient assay methods for monoamine oxidases are essential. Reviewed in this Perspective are the recent progress in the development of fluorescent probes for monoamine oxidases and their applications to enzyme assays in cells and tissues. It is evident that still there is strong need for a fluorescent probe with desirable substrate selectivity and photophysical properties to challenge the much unsolved issues associated with the enzymes and the diseases.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.689-692
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• 2001

THO imprinted membranes were prepared by the phase inversion technique using acrylonitrile-acrylic acid copolymer. Extracton of the THO template from the membrane depended on the concentration of acetic acid. The effective selectivity of the imprinted membrane was confirmed to be dependent on the temperature of coagulation ami the substrate concentration.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.1 s.190
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• pp.71-78
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• 2007

Abrasive jet machining (AJM) has been traditionally used for removing rusts or paints. Nowadays, this is promising technology for micro bulk machining where brittle substrate materials are used. In order to get accurate details, masks such as metal, polymer or elastomer is inevitable. Among them, photo polymer which is sensitive to the light has been attractive for it's high accuracy using photolithography. In this research, SU-8 as a photo polymer is used since it is adequate for making thick mask. So, this paper describes how to make AJM masks using SU-8 with a photolithography process, and investigates the characteristics of SU-8 masks during AJM process. Also, an example of fabrication using AJM was shown.