• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.4
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• pp.61-68
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• 2015

Reactive sprays of two propellant combinations(GOx/kerosene and $GN_2O$/ethanol) were observed and compared with each other as a basic research of visualizing supercritical combustion. A shadowgraph imaging method was used to visualize the reactive sprays, and shadowgraph images were converted to density gradient magnitude images to analyse the structure of reactive sprays. The gas-liquid interface of GOx/kerosene spray showed rougher boundary and steeper density gradient near the injector face than the $N_2O$/ethanol at similar combustion chamber pressure. Spray core length was calculated from averaged density gradient magnitude images and it was revealed that spray core length of GOx/kerosene was shorter than that of $GN_2O$/ethanol, although momentum flux ratio of GOx/kerosene propellant combination was lower.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.223-227
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• 2006

In this study, the combustion characteristics was studied with various oxidizer in hybrid propulsion system. In this experiments $GN_2O$ and GOX were used as oxidizer, and PE was used as fuel. The combustion behavior was explained by flame temperature with mass O/F ratio, and the use of $GN_2O$ as the oxidizer caused a increase in combustion efficiency with GOX in the same hybrid motor. The mass flow rate of gaseous oxidizer was controlled by the several chocked orifices that have different diameter, and the oxidizer supply range was $0.0138{\sim}0.0427kg/sec$. As result, the empirical relation for oxidizer type was represented by mass flux of solid fuel, it was obtained with mass transfer number, and mass flux of oxidizer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.316-319
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• 2000

In the case of immobilizing of glucose oxidase into polypyrrole (PPy) using electrosynthesis, the glucose oxidase (GOx) forms a coordinate bond with the polymer's backbone. However, because of intrinsic insulation and net-chain of the enzyme, the charge transfer and mass transport are obstructed during the film growth. Therefore, the film growth is dull. We synthesized the enzyme electrode by electropolymerization added some organic solvent, A formative seeds of film growth is delayed by adding the solvent. The delay is induced by radical transfer between the solvent and pyrrole monomer. In the case of adding ethanol, the radical transfer shares the contribution of dopant between electrolyte anion and GOx polyanion. This may lead to increase amount of immobilized the enzyme in ppy. However, adding tetrahydrofuran (THF), the radical transfer is more brisk, resulting in short chained polymer. Therefore, the doping level is lowered and then amount of immobilized of enzyme is decreased. For the UV absorption spectra of synthetic solution before synthesis and after, in the case of ethanol added, the optical density was slightly decreased for the GOx peaks. It suggests amount of GOx in the solution was decreased and amount of GOx in the film was increased. We established qualitatively that amount of immobilization can be improved by adding a little ethanol in the synthetic solution. It is due to radical transfer reaction. The radical transfer shares the contribution of dopant between small and fast electrolyte anion and big and slow GOx polyanion.

• Journal of Ginseng Research
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• v.33 no.4
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• pp.249-255
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• 2009

The oxidation of glycolate to glyoxylate, a key step in plant photorespiration, is carried out by the peroxisomal flavoprotein glycolate oxidase (EC 1.1.3.15). To investigate the altered gene expression and the role of GOX in ginseng plant defense system, a cDNA clone containing a GOX gene designated as PgGOX was isolated and sequenced from Panax ginseng. The cDNA was 692 nucleotides long and have an open reading frame of 552 bp with a deduced amino acid sequence of 183 residues. A GenBank BlastX search revealed that the deduced amino acid of PgGOX shares a high degree homology with the Glycine max (95% identity). In the present study we analyzed the expression of PgGOX under various environmental stresses at different times using real time-PCR. The results showed that the expressions of PgGOX increased after various treatments involving salt, light, cold, ABA, SA, and copper treatment.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.258-263
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• 2017

In this study, we synthesized biocatalyst consisting of glucose oxidase (GOx), polyethyleneimine (PEI) and carbon nanotube (CNT) with addition of p-benzoquinone (BQ) that was considered anodic catalysts of enzymatic biofuel cell (EBC). For doing this, PEI/CNT supporter was bonded with BQ by physical entrapping method stemmed from electrostatic attractive force ([BQ/PEI]/CNT). In turn, GOx moiety was further immobilized on the [BQ/PEI]/CNT to form GOx/[BQ/PEI]/CNT catalyst. This catalyst has a special advantage in that the BQ that has been usually dissolved into electrolyte was immobilized on supporter. According to the electrochemical analysis, maximum current density of the GOx/[BQ/PEI]/CNT catalyst was 1.9 fold better than that of the catalyst that did not entrap BQ with the value of $34.16{\mu}A/cm^2$, verifying that catalytic activity of the catalyst was enhanced by adoption of BQ. Also, when it was used as anodic catalyst of the EBC, its maximum power density was 1.2 fold better than that of EBC using the catalyst that did not entrap BQ with the value of $0.91mW/cm^2$. Based on such results, it turned out that the GOx/[BQ/PEI]/CNT catalyst was promising and viable as anodic catalyst of EBC.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.179-183
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• 2015

In this study, we propose a catalyst structure including enzyme and metal nano rod for glucose sensing. In the catalyst structure, glucose oxidase (GOx) and gold nano rod (GNR) are alternatingly immobilized on the surface of carbon nanotube (CNT), while poly(ethyleneimine) (PEI) is inserted in between the GOx and GNR to fortify their bonding and give them opposite polarization ($[GOx/GNR]_nPEI/CNT$). To investigate the impact of $[GOx/GNR]_nPEI/CNT$ on glucose sensing, some electrochemical measurements are carried out. Initially, their optimal layer is determined by using cyclic voltammogram and as a result of that, it is proved that $[GOx/GNR/PEI]_2/CNT$ is the best layer. Its glucose sensitivity is $13.315{\mu}AmM^{-1}cm^{-2}$. When it comes to the redox reaction mechanism of flavin adenine dinucleotide (FAD) within $[GOx/GNR/PEI]_2/CNT$, (i) oxygen plays a mediator role in moving electrons and protons generated by glucose oxidation reaction to those for the reduction reaction of FAD and (ii) glucose does not affect the redox reaction of FAD. It is also recognized that the $[GOx/GNR/PEI]_3/CNT$ is limited to the surface reaction and the reaction is quasi-reversible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.223-226
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• 2003

We propose an improvement method for a $\underline{G}ate$ $\underline{OX}ide(GOX)$ thinning at the edge of $\underline{S}hallow$ $\underline{T}rench$ $\underline{I}solation(STI)$, when STI is adopted to Dual Gate Oxide(DGOX) Process. In the case of SOC(System On-a-Chip), the DGOX process is usually used for realizing both a low and a high voltage parts in one chip. However, it is found that the severe GOX thinning occurs from at STI top edge region and a dent profile exists at the top edge of STI, when conventional DGOX and STI process carried out in high density device chip. In order to overcome this problem, a new DGOX process is tried in this study. And we are able to prevent the GOX thinning by H2 anneal, partially SiN liner skip, and a method which is merged a thick sidewall oxide(S/O) with a SiN pull-back process. Therefore, a good subthreshold characteristics without a double hump is obtained by the prevention of a GOX thinning and a deep dent profile.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.44-49
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• 2009

Conjugated nanocrystals using CdSe/ZnS core/shell nanocrystal quantum dots modified by organic linkers and glucose oxidase (GOx) were prepared for use as biosensors. The trioctylphophine oxide (TOPO)-capped QDs were first modified to give them water-solubility by terminal carboxyl groups that were bonded to the amino groups of GOx through an EDC/NHS coupling reaction. As the glucose concentration increased, the photoluminescence intensity was enhanced linearly due to the electron transfer during the enzymatic reaction. The UV-visible spectra of the as-prepared QDs are identical to that of QDs-MAA. This shows that these QDs do not become agglomerated during ligand exchanges. A photoluminescence (PL) spectroscopic study showed that the PL intensity of the QDs-GOx bioconjugates was increased in the presence of glucose. These glucose sensors showed linearity up to approximately 15 mM and became gradually saturated above 15 mM because the excess glucose did not affect the enzymatic oxidation reaction past that amount. These biosensors show highly sensitive variation in terms of their photoluminescence depending on the glucose concentration.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2421-2429
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• 2018

Thiol-based self-assembled anchor linked to glucose oxidase (GOx) and gold nanoparticle (GNP) cluster is suggested to enhance the performance of glucose biosensor. By the adoption of thiol-based anchors, the activity of biocatalyst consisting of GOx, GNP, polyethyleneimine (PEI) and carbon nanotube (CNT) is improved because they play a crucial role in preventing the leaching out of GOx. They also promote electron collection and transfer, and this is due to a strong hydrophobic interaction between the active site of GOx and the aromatic ring of anchor, while the effect is optimized with the use of thiophenol anchor due to its simple configuration. Based on that, it is quantified that by the adoption of thiophenol as anchor, the current density of flavin adenine dinucleotide (FAD) redox reaction increases about 42%, electron transfer rate constant ($k_s$) is $9.1{\pm}0.1s^{-1}$ and the value is 26% higher than that of catalyst that does not use the anchor structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.239-242
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• 2008

Combustion Characteristic with initial port-diameter of fuel was studied in hybrid propulsion system using cylindrical single port-grain. In order to understand a variation of combustion characteristic with initial port-diameter, experimental studies were performed with the GOX and $GN_2O$ as oxidizer, and PE as fuel. As results, burning rate decreased with increase of initial port-diameter of fuel. And the variation of burning rate with using $GN_2O$ is smaller than using GOX.