• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1666-1671
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• 2022

The structure of a high-power gain-flattened long wavelength band (L-band) optical amplifier was optimized, which was implemented for 64-channel wavelength division multiplexed optical signals with a channel spacing of 50 GHz. The output characteristics of this L-band amplifier were measured and analyzed. The amplifier of the optimized two-stage amplification configuration had a flattened gain of 20 dB within 1 dB deviation between 1570 and 1600 nm for -2 dBm input power condition. The noise figure under this condition was minimized to within 6 dB in the amplification bandwidth. The gain flattening was realized by considering only the characteristics of gain medium in the amplifier without using additional optical or electrical devices. The proposed amplifier consisted of two stages of amplification stages, each of which was based on the erbium-doped fiber amplifier (EDFA) structure. The erbium-doped fiber length and pumping structures in each stage of the amplifier were optimized through experiments.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.2
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• pp.129-136
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• 2010

In order to evaluate anti-wrinkle activity of Carex humilis extract, free radical scavenging activity, elastase inhibitory activity and reduction of expression Matrix metalloproteinase-1 (MMP-1) mRNA and MMP-1 protein were investigated. The roots of Carex humilis were extracted with 95 % ethanol and successively partitioned with organic solvents with increasing polarity of the solvents. Each fraction of organic solvent were investigated by using free radical scavenging activity and elastase inhibitory activity test. Among them, EtOAc fraction showed antioxidant activity ($SC_{50}$=4.89 ${\mu}g/mL$) and elastase inhibitory activity ($IC_{50}$=23.5 ${\mu}g/mL$). EtOAc fraction was developed on silica gel by open-column chromatography and consecutively re-developed on C18 resin by prep-HPLC to give ${\alpha}$-viniferin as a major component, which was confirmed by spectrometric analysis. In the assay on expression of MMP-1 mRNA by RT-PCR and protein by western-blot, EtOAc layer (10 ~ 100 ${\mu}g/mL$) was reduced about 50 ~ 60 %, 50 ~ 65 % respectively and ${\alpha}$-viniferin (0.5 ~ 2 ${\mu}g/mL$) was inhibited about 60 ~ 75 %, 55 ~ 65 % respectively in human fibroblast. Therefore, our findings suggest that EtOAc layer of Carex humilis containing ${\alpha}$-viniferin can be useful as an active ingredient for cosmeceuticals of anti-wrinkle effects.

• Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.51-56
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• 2015

A 8-week trial was conducted to evaluate the effects of photoperiod manipulation on the growth performance and hematological parameters of juvenile Caspian roach, Rutilus rutilus caspicus (average weight $1.46{\pm}0.12g$ mean${\pm}$SD) reared under five photoperiods (24 h Light, 24L; 18 h Light & 6 h Dark, 18L:6D; 12 h Light & 12 h Dark, 12L:12D; 6 h Light & 18 h Dark, 6L:18D; 24 h Dark, 24D) with constant light intensity 1,500 lx on the water surface. Triplicate of 20 fish were allocated into each of 15 fiberglass tanks of 50 L capacity and they were fed three times per day with the commercial feed (SFK, Co., Sari - Iran) contains 50.0% protein and 10.5% lipid. At the end of experimental period, final body weight, weight gain and specific growth rates of fish exposed to 24L were significantly higher than those of fish exposed to 12L:12D, 6L:18D and 24D (P < 0.05). Red blood cell and hemoglobin of fish exposed to 24L were significantly higher than those of fish exposed to 24D. No significant difference observed in hematocrit, white blood cell and plasma glucose among the different treatments groups. Therefore, these results demonstrated that the growth performance of juvenile Caspian roach can be significantly stimulated by using 24L and 18L:6D photoperiods without any measurable significant stress response such as plasma glucose concentration.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.3
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• pp.237-245
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• 2011

In order to investigate the possibility of Inonotus obliquus extract as an active ingredient for wrinkle-care cosmetics, we prepared 70 % ethanolic extract of Inonotus obliquus and measured its DPPH radical scavenging activity and elastase inhibitory activity. We also evaluated the effect of Inonotus obliquus extract on expression of MMPs and HAS-2 in fibroblast and HaCaT cell, respectively. Inonotus Obliquus extract showed DPPH radical scavenging activity and elastase inhibitory activity in a dose-dependant manner ($SC_{50}$ = 91 ${\mu}g$/mL, $IC_{50}$=124 ${\mu}g$/mL). Inonotus obliquus extract inhibited the expression of MMP-1 mRNA 50 ~ 79 % at concentrations of 5 ~ 25 ${\mu}g$/mL, and reduced the expression of MMP-2 around 20 % at a concentration of 10 ${\mu}g$/mL. And it also reduced the expression of MMP-9 54 ~ 70 % in tconcentrations of 5 to 25 ${\mu}g$/mL. Furthermore, Inonotus obliquus extract increased HAS-2 mRNA expression in a dose-dependent manner in concentrations of 5 to 25 ${\mu}g$/mL without cytotoxicity. These results suggested that Inonotus Obliquus extract could be useful as an active ingredient for wrinkle-care cosmetics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.4
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• pp.357-363
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• 2011

In this study, the antioxidative effects and inhibitory activities on tyrosinase of Rheum undulatum (R.undulatum) L. extracts were investigated. 50 % ethanol extract, ethyl acetate and aglycone fractions of R. undulatum L. were used in experiments. The DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activities ($FSC_{50}$) of R. undulatum L. extracts was lower than (+)-${\alpha}$-tocopherol, known as a typical antioxidant. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of aglycone fraction on ROS generated in $Fe^{3+}$-EDTA/$H_2O_2$ system using the luminol-dependent chemiluminescence assay showed the most prominent effect at a concentration of $0.265\;{\mu}g/mL$. The cellular protective effects of extract/fractions of R. undulatum L. on the rose-bengal sensitized photohemolysis of human erythrocytes were increased in a concentration dependent manner ($1{\sim}50\;{\mu}g/mL$). Especially, aglycone fraction in $10\;{\mu}g/mL$ concentration showed the most protective effect among extracts (${\tau}_{50}$, 757.0 min). The inhibitory effects ($IC_{50}$, $11.20\;{\mu}g/mL$) on tyrosinase of aglycone fraction was much higher than arbutin ($226.88\;{\mu}g/mL$), known as a whitening agent. These results indicate that R. undulatum L. extracts can be used as antioxidant. Particularly, aglycone fraction of R. undulatum L. showed superior antioxdative activity and high inhibitory effect on tyrosinase. Therefore, aglycone fraction of R. undulatum L. could be applicable to new functional cosmetics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.3
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• pp.275-282
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• 2012

In this study, the antioxidative effects of extracts from different parts of Juncus effusus L. were investigated. The three parts (above-ground part, below-ground part, medulla part) were selected. 50 % ethanol extract, ethyl acetate and aglycone fractions of J. effusus L. were used in experiments. The highest DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activities ($FSC_{50}$) was shown by medulla part (42.9 ${\mu}g/mL$) in 50 % ethanol extracts, below-ground part (12.1 ${\mu}g/mL$) in ethyl acetate fractions, and below-ground part (12.1 ${\mu}g/mL$) in aglycone fractions. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) on ROS generated in $Fe^{3+}$-EDTA/$H_2O_2$ system using the luminol-dependent chemiluminescence assay showed the most prominent effect of medulla part (0.29 ${\mu}g/mL$) in 50 % ethanol extracts, below-ground part (0.25 ${\mu}g/mL$) in ethyl acetate fractions, and medulla part (0.20 ${\mu}g/mL$) in aglycone fractions. The cellular protective effects of extract/fractions of J. effusus L. on the rose-bengal sensitized photohemolysis of human erythrocytes were increased in a concentration dependent manner (0.5 ~ 10 ${\mu}g/mL$). Especially, aglycone fraction of medulla part at a concentration of 10 ${\mu}g/mL$ showed the most prominent protective effect among all extracts (${\tau}_{50}$, 321.0 min). These results indicate that extracts from below-ground part and medulla part of J. effusus L. extracts can be used as an natural antioxidant. Particularly, J. effusus L. can protect suggesting a high ${\tau}_{50}$ skin where many $^1O_2$ was generated by sunlight exposure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.112-119
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• 1995

Measurements of the local heat transfer coeffcients on a spherically concave surface with a round impinging jet are presented. The liquid crystal transient method was used for these measurements. This method, which is a variation on the transient method, suddenly exposes a preheated wall to an impinging jet while video recording the response of liquid crystals for the measurement of the surface temperature. The Reynolds numbers used were 1,000, 23,000 and 50,000 and the nozzle-to-jet distance was L/d=2, 4, 6, 8, 10. Presented results are compared to previous measurements for flat plate. In the experiment, the local heat transfer Nusselt numbers on a concave surface are higher than those on a flat plate. Maximum Nusselt number at all region occured at L/d=6 and second maximum in the Nusselt number occured at R/d=2 for both Re=50,000 and Re=23,000 in case of L/d=2 and for only Re=50,000 in case of L/d=4. All other cases exhibit monotonically decreasing value of the Nusselt number along the curved surface.

• Analytical Science and Technology
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• v.31 no.6
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• pp.219-224
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• 2018

The fruit and stem of Opuntia ficus-indica var. aboten (OFS), a native plant of Jeju Island, are considered a safe food source. Moreover, stem extracts have been previously reported to possess a variety of biological effects (e.g. anti-inflammatory and anti-oxidant, including the ability to partially ameliorate cognitive impairment), suggesting that this plant may have utility as a functional food. The present study investigated whether fermentation by lactic acid bacteria enhances the biological effects of OFS extracts. The acetylcholinesterase (AChE) inhibitory activity of fermented or non-fermented OFS extracts was evaluated, and the content of marker components dihydrokaempferol (DHK) and quercetin-3-methyl ether (3-MeQ) was analyzed using high-performance liquid chromatography. Fermented (relative to non-fermented) OFS extracts exhibited improved AChE inhibitory activity ($IC_{50}=28.35 mg/mL$), with AChE inhibitory activity resulting from fermentation by L. plantarum ($IC_{50}=12.56mg/mL$) exceeding that resulting from fermentation by L. fermentum ($IC_{50}=17.71mg/mL$). Furthermore, fermented (relative to non-fermented) OFS extracts exhibited a 16.7 % increase in DHK content, and 3-MeQ content of OFS extracts fermented by L. plantarum and L. fermentum increased by 28.6 % and 21.4 %, respectively. Therefore, OFS stem extract AChE inhibitory activity, as well as DHK and 3-MeQ content, was enhanced by fermentation with Lactobacillus spp. This suggests that fermented OFS extracts may contribute to prevention or improvement of cognitive impairment. These data are anticipated to be useful in the development of enhanced-efficacy OFS products.

• Journal of Microbiology and Biotechnology
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• v.16 no.11
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• pp.1678-1683
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• 2006

A novel suspension-phase enzyme reaction system for the intermolecular transglycosylation of L-ascorbic acid into 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid supplementing extrusion starch as the glycosyl donor was developed using cyclodextrin glucanotransferase from Thermoanaerobacter sp. A high conversion yield compared to the conventional soluble-phase enzyme reaction system using cyclodextrins and soluble starch was achieved. The optimal reaction conditions were 2,000 units of cycIodextrin glucanotransferase, 20 g/l of L-ascorbic acid, and 50 g/l of extrusion starch at $50^{\circ}C$ for 24 h. The new suspension-phase enzyme reaction system also exhibited several distinct advantages other than a high conversion yield, including a lower accumulation of oligosaccharides and easily separable residual extrusion starch by centrifugation or filtration in the reaction mixture, which will facilitate the purification of 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid. The new suspension-phase enzyme reaction system seems to be potentially applicable as the industrial process for the production of thermally and oxidatively stable 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1169-1176
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• 2010

The RF front-end for L1/L2 dual-band Global Positioning System(GPS) receiver is presented in this paper. The RF front-end(down-converter) using low IF architecture consists of a wideband low noise amplifier(LNA), a current mode logic(CML) frequency divider and a I/Q down-conversion mixer with a poly-phase filter for image rejection. The current bleeding technique is used in the LNA and mixer to obtain the high gain and solve the head-room problem. The common drain feedback is adopted for low noise amplifier to achieve the wideband input matching without inductors. The fabricated RF front-end using $0.18{\mu}m$ CMOS process shows a gain of 38 dB for L1 and 41 dB for L2 band. The measured IIP3 is -29 dBm in L1 band and -33 dBm in L2 band, The input return loss is less than -10 dB from 50 MHz to 3 GHz. The measured noise figure(NF) is 3.81 dB for L1 band and 3.71 dB for L2 band. The image rejection ratio is 36.5 dB. The chip size of RF front end is $1.2{\times}1.35mm^2$.