• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.179-182
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• 2006

The effect of electron beam irradiation on dye sensitized solar cell (DSSC) has been studied to examine degradation of DSSC. The high-energy electron beam irradiation affects on the materials and performance of dye sensitized solar cells. We have checked the effects of electron beam irradiation of $TiO_2$ substrate with and without dye adsorption on the photovoltaic performances of resulting DSSCS and also studied the structural and electrical properties of polymers after irradiation. All solar cells materials were irradiated by electron beams with an energy source of 2MeV at different dose rates of 60 kGy, 120 kGy 240 kGy and 900 kGy and then their photoelectrical parameters were measured at 1 sun $(100 mW/cm^2)$. It was shown that the efficiency of DSSC was decreased as increasing the dose of e-beam irradiation due to lowering in $TiO_2$ crystallinity, decomposition of dye and oxidation of FTO glasses. On the other hand, the performance of solid-state DSSC with polyethylene oxide based electrolyte was improved after irradiation of e-beam due to enhancement of its conductivity and breakage of crosslinking.

• Journal of Nutrition and Health
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• v.35 no.10
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• pp.1031-1037
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• 2002

The purpose of present study was to evaluate the effect of endurance exercise training on skeletal muscle free amino acid concentrations, and differences in free amino acid concentration between soleus muscle which consists of mostly slow twitch oxidative fiber and extensor digitorum longus muscle which consists of fast twitch oxidative glycolytic fiber. Sixteen male SD rats (4 weeks old) were randomly devided into two groups, and fed a purified AIN-93M diet with or without aerobic exercise training according to the protocol (running on the treadmill at 25 m/min for 60 min, 5 days a week) for 6 weeks. Exercise-training for 6 weeks significanly reduced the commulative body weight gain (p＜0.05) and food efficiency ratio (p＜0.01) of rats. The result showing mitochondrial citrate synthase activity of soleus muscle was significantly higher in exercise-trained rats compared to the value for control animals (p＜0.01) indicates aerobic exercise-training was successfully accomplished in the trained group. No difference was found in the muscle aminogram pattern between soleus muscle and extensor digitorum longus muscle of control animals. However, free amino acid concentrations of soleus muscle were from 1.2 to 3.9 times of those found in extensor digitorum longus muscle of control rats, depending on an individual amino acid. Intermediate level of endurance exercise training for 6 weeks did not influence concentrations of most of free amino acid in soleus muscle of rats collected at an overnight fasted and rested state. In contrast, isolucine and leucine concentrations in extensor digitorum longus muscle of exercise-trained rats were significantly lower than those for control animals. These results indicate that aerobic energy metabolism had not been efficiently conducted, and thereby the utilization of BCAA for energy substrate was enhanced in fast twitch oxidative glycolytic fibers of extensor digitorum longus muscle of rats followed exercise-training protocol for 6 weeks.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.111-116
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• 1996

Polyphenol oxidase(PPO) isolated from the crude extract of ascidian, Halocynthia roretzi, showed higher affinity for catechol than tyrosine or DL-DOPA. Successful enzyme assay could be performed at $25^{\circ}C$, 10min. by mixing 0.2ml of crude enzyme extract with 2.8ml of 0.13M catechol in 0.1M sodium phosphate buffer(pH 6.4). The specific activity of PPO which had been purified with a combination of ammonium sulfate treatment, ion exchange chromatography on DEAE-cellulose, and gel filtration on Sepharose 6B was 13-fold disc gel electrophoresis. The activity of PPO was stable from pH 5.0 to 8.0 and showed the peak activity at pH 6.4 .The optimum reaction temperature for PPO oxidation on catechol was 35$^{\circ}C$ and those enzyme were heat stable up to 4$0^{\circ}C$. Molecular weigth of the enzyme was estimated about 170kDa. One molecule was found to be composed of gour subunits. Two of them had molecular weigh of 55kDa and the others 30kDa. The {TEX}$K_{m}${/TEX} values, {TEX}$V_{max}${/TEX} and catalytic efficiency({TEX}$V_{max}${/TEX}/{TEX}$K_{m}${/TEX}) for catechol were 0.12mM, 2.5mM/liter/min. and {TEX}$0.18min^{-1}${/TEX} respectively. The substrate affinity and electrophorectic pattern suggested that the enzyme of ascidian was considered to be not tyosine but catechol oxidase.

• Current Applied Physics
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• v.18 no.12
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• pp.1496-1506
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• 2018

Organic/inorganic ultraviolet photodetector was fabricated using thermal evaporation technique. Organic/inorganic heterojunction based on thermally evaporated copper (II) acetylacetonate thin film of thickness 200 nm deposited on an n-type silicon substrate is introduced. I-V characteristics of the fabricated heterojunction were investigated under UV illumination of intensity $65mW/cm^2$. The diode parameters such as ideality factor, n, barrier height, ${\Phi}_B$, and reverse saturation current, $I_s$, were determined using thermionic emission theory. The series resistance of the fabricated diode was determined using modified Nord's method. The estimated values of series resistance and barrier height of the diode were about $0.33K{\Omega}$ and 0.72 eV, respectively. The fabricated photodetector exhibited a responsivity and specific detectivity about 9 mA/W and $4.6{\times}10^9$ Jones, respectively. The response behavior of the fabricated photodetector was analyzed through ON-OFF switching behavior. The estimated values of rise and fall time of the present architecture under UV illumination were about 199 ms and 154 ms, respectively. Finally, enhancing the photoresponsivity of the fabricated photodetector, post-deposition plasma treatment process was employed. A remarkable modification of the device performance was noticed as a result of plasma treatment. These modifications are representative in a decrease of series resistance and an increase of photoresponsivity and specific detectivity. The process of plasma treatment achieved an increment of external quantum efficiency from 5.53% to 8.34% at -3.5 V under UV illumination.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.468-479
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• 2016

In order to supply power to online monitoring systems that are attached to high voltage catenary or overhead wires, a wireless power transfer system is required that is able to transmit power over the insulation gap. Such wireless power transfer systems have transmitter and receiver coils that have diameters of over 10cm. This paper focused on an investigation of the sources of loss in the coils when the coils are fabricated using printed circuit board technology. Using finite element simulation results, it has been shown that the dielectric loss in the substrate was the dominant source of the total loss. It has been demonstrated that the selection of a proper dielectric material was the most critical factor in reducing the loss. For further reduction of the loss, the distributed tuning capacitor method and the slotting of the inter-turn spaces have been proposed. For the evaluation of the proposed methods, four coils have been fabricated and their equivalent series resistances and quality factors were measured. Measured quality factors were greater than 300, which means that these devices will be helpful in achieving high coil-to-coil efficiency.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.599-604
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• 2021

In the information age, internet was developed from the wired access to the wireless Internet access. When a surge in demand for wireless Internet access, efficiency and performance of 2.4 and 5GHz band which leads to saturation of the communication was significantly fall. In this paper, we studied the design and fabrication of slot patch antenna to be used in wireless communication systems operating at around 10GHz band. To obtain optimal antenna parameters such as patch size, inter patch space, sL, sW, feed L, feed w, slot patch antenna was simulated by HFSS(High Frequency Structure Simulator). From these parameters, slot and patch antenna is fabricated using FR-4 substrate of dielectric constant 4.4. The characteristics of fabricated antenna were analyzed by network analyzer. The fabricated slot patch antenna showed a center frequency as 10.23GHz, the minimum return loss as -32dB, and -10dB bandwidth as 420MHz respectively.

• Journal of Microbiology and Biotechnology
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• v.31 no.3
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• pp.419-428
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• 2021

To efficiently recycle GH78 thermostable rhamnosidase (TpeRha) and easily separate it from the reaction mixture and furtherly improve the enzyme properties, the magnetic particle Fe3O4-SiO2-NH2-Cellu-ZIF8 (FSNcZ8) was prepared by modifying Fe3O4-NH2 with tetraethyl silicate (TEOS), microcrystalline cellulose and zinc nitrate hexahydrate. FSNcZ8 displayed better magnetic stability and higher-temperature stability than unmodified Fe3O4-NH2 (FN), and it was used to adsorb and immobilize TpeRha from Thermotoga petrophilea 13995. As for properties, FSNcZ8-TpeRha showed optimal reaction temperature and pH of 90℃ and 5.0, while its highest activity approached 714 U/g. In addition, FSNcZ8-TpeRha had better higher-temperature stability than FN. After incubation at 80℃ for 3 h, the residual enzyme activities of FSNcZ8-TpeRha, FN-TpeRha and free enzyme were 93.5%, 63.32%, and 62.77%, respectively. The organic solvent tolerance and the monosaccharides tolerance of FSNcZ8-TpeRha, compared with free TpeRha, were greatly improved. Using naringin (1 mmol/l) as the substrate, the optimal conversion conditions were as follows: FSNcZ8-TpeRha concentration was 6 U/ml; induction temperature was 80℃; the pH was 5.5; induction time was 30 min, and the yield of products was the same as free enzyme. After repeating the reaction 10 times, the conversion of naringin remained above 80%, showing great improvement of the catalytic efficiency and repeated utilization of the immobilized α-L-rhamnosidase.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.299-307
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• 2019

The purpose of this study was to investigate the effect of low temperature thermal pre-treatment on biodegradation of waste activated sludge for anaerobic digestion as a countermeasure for increasing sludge generation. The experimental condition was accomplished in 2 %, 4 %, and 6 % TS concentration, and $70^{\circ}C$, $80^{\circ}C$, $90^{\circ}C$ of temperature for a maximum of 120 minutes retention time. Then, it was followed by analysis of physical/chemical properties, BMP test and composition of biogas. The biogas characteristic was evaluated by applying the modified Gomperz model. As a result, solubility of dissolved substrate, such as $SCOD_{Cr}$, soluble carbohydrate, and soluble protein, and biogas production increased as temperature increased. Solubilization efficiency at $90^{\circ}C$ was 18.4 %, 17.03 % and 16.88% in 2 %, 4 %, and 6 % TS concentration respectively. Also, solubilization rates of carbohydrate and protein similarly increased. BMP test results also showed that methane production in excess sludge increased to 0.194, 0.187 and $0.182m^3/kg$ VS. respectively, and lag phase decreased to 0.145, 0.220, 0.351 day due to acceleration of the hydrolysis step. Consequently, low-temperature thermal pre-treatment could increase biodegradability of sludge, positively affecting biogas production and sludge reduction.

• Journal of Microbiology and Biotechnology
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• v.29 no.1
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• pp.44-54
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• 2019

Geldanamycin and its derivatives, inhibitors of heat shock protein 90, are considered potent anticancer drugs, although their biosynthetic pathways have not yet been fully elucidated. The key step of conversion of 4,5-dihydrogeldanamycin to geldanamycin was expected to catalyze by a P450 monooxygenase, Gel16. The adequate bioconversions by cytochrome P450 mostly rely upon its interaction with redox partners. Several ferredoxin and ferredoxin reductases are available in the genome of certain organisms, but only a few suitable partners can operate in full efficiency. In this study, we have expressed cytochrome P450 gel16 in Escherichia coli and performed an in vitro assay using 4,5-dihydrogeldanamycin as a substrate. We demonstrated that the in silico method can be applicable for the efficient mining of convenient endogenous redox partners (9 ferredoxins and 6 ferredoxin reductases) against CYP Gel16 from Streptomyces hygroscopicus. The distances for ligand FDX4-FDR6 were found to be $9.384{\AA}$. Similarly, the binding energy between Gel16-FDX4 and FDX4-FDR6 were -611.88 kcal/mol and -834.48 kcal/mol, respectively, suggesting the lowest distance and binding energy rather than other redox partners. These findings suggest that the best redox partners of Gel16 could be NADPH ${\rightarrow}$ FDR6 ${\rightarrow}$ FDX4 ${\rightarrow}$ Gel16.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.163-170
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• 2021

Enzyme replacement therapy for lysosomal storage diseases usually requires recombinant enzymes containing mannose-6-phosphate (M6P) glycans for cellular uptake and lysosomal targeting. For the first time, a strategy is established here for the in vitro mannosyl-phosphorylation of high-mannose type N-glycans that utilizes a recombinant Mnn14 protein derived from Saccharomyces cerevisiae. Among a series of N-terminal- or C-terminal-deleted recombinant Mnn14 proteins expressed in Pichia pastoris, rMnn1477-935 with deletion of N-terminal 76 amino acids spanning the transmembrane domain (46 amino acids) and part of the stem region (30 amino acids), showed the highest level of mannosyl-phosphorylation activity. The optimum reaction conditions for rMnn1477-935 were determined through enzyme assays with a high-mannose type N-glycan (Man8GlcNAc2) as a substrate. In addition, rMnn1477-935 was shown to mannosyl-phosphorylate high-mannose type N-glycans (Man7-9GlcNAc2) on recombinant human lysosomal alpha-glucosidase (rhGAA) with remarkably high efficiency. Moreover, the majority of the resulting mannosyl-phosphorylated glycans were bis-form which can be converted to bis-phosphorylated M6P glycans having a superior lysosomal targeting capability. An in vitro N-glycan mannosyl-phosphorylation reaction using rMnn1477-935 will provide a flexible and straightforward method to increase the M6P glycan content for the generation of "Biobetter" therapeutic enzymes.