• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.229-232
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• 2001

4H-SIC(silicon carbide) MESFET large signal model was studied using modified Materka-Kacprzak large signal MESFET model. 4H-SiC MESFET device simulation have been conducted by Silvaco's 2D device simulator, ATLAS. The result is modeled using modified Materka large signal model. simulation and modeling results are -8V pinch off voltage, under $V_{GS=0V}$, $V_{DS=25V}$ conditions, $I_{DSS=270㎃}$mm, $G_{m=45㎳}$mm were obtained. Through the power simulation 2GHz, at the bias of $V_{GS=-4V}$ and $V_{DS=25V}$, 10dB Gain, 34dBm(1dB compression point)output power, 7.6W/mm power density, 37% PAE(power added efficiency) were obtained.d.d.d.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.62-66
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• 2016

This paper presents a MedRadio-band low power low noise amplifier for Medical Devices. A proposed MedRadio-band low power low noise amplifier adopts a current-reuse resistive feedback topology to increase overall gm and reduce power consumption. The gain of the LNA increases by the Q-factor of the additional series RLC input matching network, and its noise figure is minimized by the similar factor. Furthermore, it consumes low power because of low supply voltage and current reuse technique. By exploiting the $g_m$-booting and matching network property, the proposed MedRadio-band low noise amplifier achieves a noise figure of 0.85 dB, a voltage gain of 30 dB, and IIP3 of -7.9 dBm while consuming 0.18 mA from a 1 V supply voltage in $0.13{\mu}m$ CMOS technology.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.191-200
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• 2005

The main purpose of the present study was to find the effect of short term creating loading on repeated bouts of kicking, plasma creating phosphokinase and anaerobic power in male taekwondo player from high school. Sixteen male were randomly assigned to two groups. They were tested before and after 6 days of placebo$(4{\times}5g\;glucose\;d^{-1},\;N=11)$ or Creatine monohydrate loading$(consume\;0.3g\;kg^{-1},\;N=11)$. Repeated bouts of kicking was tested through maximal front kicking continuously for 1 minute and took a rest for 30 seconds, after 30 seconds rest they should have to start kicking again. They repeated it 2 times more(total 3 sets) and the kicking times were measured each sets. Also, body composition, CPK, mean power and peak power were measured before and after experiment. The following results were obtained from this study; 1. The kicking test was significantly increased at 1, 2, 3 sets only in creatine loading group(p<.05, p<.01). 2. Only creatine loading group was significantly increased of plasma creatine phosphokinase(p<.01). 3. Only creatine loading group were significantly increased both of mean power and peak power(p<.05; p<.01). These results suggest that short creatine loading was effective diet protocol in taekwondo player from male high school.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.125-130
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• 2009

With respect to the goal of achieving at least 50[%] reduction of global emissions by 2050, the G8 leaders agreed to seek to share and adopt it with all Parties to the UNFCCC in the 34th Group of Eight Summit held in Toyako, Japan in July 2008. Korea is also expected to obey the Kyoto Protocol starting in 2013, which will result in a serious shock especially to the electric power industry. The power plants burning the fossil fuel produce more than 20 percent of national $CO_2$ emission. This paper presents an economic feasibility study on fuel transfer for a thermal power plant considering $CO_2$ emission cost. Calculation of the breakeven point for the fuel transfer from LNG to heavy oil of D power plant is demonstrated using the input-output coefficients obtained by the performance test.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.115-120
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• 2015

$K_2CO_3$-based dry regenerable sorbents were prepared by spray-drying techniques to improve mass produced $K_2CO_3-Al_2O_3$ sorbents (KEP-CO2P, hereafter), and then tested for their $CO_2$ sorption capacity by a $2,000Nm^3/h$ (0.5 MWe) $CO_2$ capture pilot plant built for Unit 3 of the Hadong thermal power station in 2010. Each of the sample sorbents contained 35 wt.% $K_2CO_3$ as the active materials with various support materials such as $TiO_2$, MgO, Zeolite 13X, $Al_2O_3$, $SiO_2$ and hydrotalcite (HTC). Their physical properties and reactivity were tested to evaluate their applicability to a fluidized-bed or fast transport-bed $CO_2$ capture process. The $CO_2$ sorption capacity and percentage utilization of $K_2CO_3$-MgO based sorbent, Sorb-KM2, was $8.6g-CO_2/100g$-sorbents and 90%, respectively, along with good mechanical strength for fluidized-bed application. Sorbs-KM2 and KT were almost completely regenerated at $140^{\circ}C$. No degradation of Sorb-KM by $SO_2$ added as a pollutant in flue gas was observed during a cycle test.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.281-286
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• 2019

Raman spectra of a-C:H thin films deposited with an unbalanced magnetron sputtering system showed that the G peak shifted to a higher wavenumber as the target power density increased and $I_D/I_G$ ratio increased from 0.902 to 1.012. Moreover, the transmittance of a-C:H films fabricated at 60 nm tended to decrease with increasing target power density; at 550 nm in the visible light region, the transmittance decreased from 69% to 58%. The rms surface roughness values of the a-C:H thin films decreased with increasing target power density, and varied from 1.11 nm to 0.71 nm. In order to achieve efficient light trapping, the light scattering at the rough interface must be enhanced. Consequently, the surface roughness of the thin film will decrease with the target power density. Further, the refractive index and reflectivity of the a-C:H thin films increased with increasing target power density; however, the Brewster angle decreased with the target power density. Hence, dye-sensitized solar cells using an a-C:H antireflective coating increased the CE, $V_{OC}$, and $J_{SC}$ by approximately 8.6%, 5.5%, and 4.5%, respectively.

• Food Science and Preservation
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• v.10 no.4
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• pp.540-546
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• 2003

Biological activities of solvent fractions obtained from Cnsicum annuum leaves, being used in material of functional food, were examined by the methods of DPPH scavenging activity, reducing power, nitrite scavenging activity, antimicrobial activity and inhibitory effect on tyrosinase activity. The highest yield was obtained from water fraction, where as the lowest yield was obtained from ethyl acetate traction, 16.9% and 0.6%, respectively. Hydrogen donating activity of Capsicum annuum leaves in increased with increasing amount of extract. Reducing power of the ethyl acetate fraction is increased as the amount of extract is increased. Even in the presence of 900 $\mu\textrm{g}$ of ethyl acetate fraction, reducing power was significantly higher than it was fer the control in which there was no extract. Among the various solvent fractions, ethyl acetate fraction showed the strongest scavenging effect on hydrogen peroxide. Nitrite scavenging effects of all concentrations diminished at higher pH, while in the case of pH 1.2, it showed a nitrite scavenging effect of more than 90% at concentration above of ethyl acetate fraction 500 $\mu\textrm{g}$. Among the various solvent fractions from methanol extract of Capsicum annuum leaves, ethyl acetate and butanol fraction showed the strongest antimicrobial activity. Antimicrobial activity of ethyl acetate fraction was 20 mm against Bacillus cereus, 18 mm against Staphylococcus aureus and 17 mm against Streptococcus mutans. Ethyl acetate fraction showed the strongest of inhibitory activity of tyrosinase.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.1
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• pp.68-73
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• 2011

Total anthocyanin and color intensity contents of wild grape wine were $4.3{\pm}0.3%$ and $10.2{\pm}0.8%$, respectively. The contents of total phenols and flavonoid in wild grape wine were $18.8{\pm}3.9$ mg/100 g, $0.5{\pm}0.2$ mg/100 g, respectively. Total mineral content in wild grape wine was $22.6{\pm}0.2$ mg/100 g and the 10 minerals of the potassium content ($5.3{\pm}0.2$ mg/100 g) was the highest. Electron donating abilities of wild grape juice at concentration of 1,000 ${\mu}L/mL$ were $90.4{\pm}1.8%$. Reducing power of wild grape wine at concentration of 1,000 ${\mu}L/mL$ were 0.932. The electron donating abilities and reducing power were increased significantly by increased the sample concentration in the reaction mixture. The nitrite scavenging ability was dependent on pH of reaction mixture and sample concentration. The nitrite scavenging ability of wild grape win was $76.3{\pm}1.3%$ at concentration of 1,000 ${\mu}L/mL$ under pH 1.2.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.5
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• pp.695-701
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• 2015

This study was conducted to evaluate the effects of drying and extraction methods on antioxidant activity and total phenol content of Gnaphalium affine D. DON (GA). Hot-air, shade-drying, and freeze-drying were used for drying, after which magnetic stirring and ultrasonification were applied. Extracting solvents were water, 80% ethanol, and 80% methanol. Total phenol content was highest in 80% ethanol extract of freeze-dried and stirred GA. Total flavonoid content was highest in 80% methanol extract of freeze-dried and stirred GA. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was higher in 80% methanol and 80% ethanol extracts than in water extract. 2,2-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity was highest in 80% ethanol extract of shade-dried and ultrasonicated GA. Reducing power was generally higher in 80% methanol extract than in 80% ethanol and water extracts of GA. Total phenol and total flavonoid contents were highly correlated with DPPH radical scavenging activity and reducing power, respectively. This result implies that the antioxidant activity of GA can be attributed to phenol compounds such as flavonoids. Conclusively, phenol compounds such as flavonoids are responsible for the antioxidant activity of GA, and there was no significant effect of drying and stirring conditions on antioxidant activity of 80% ethanol. Meanwhile, DPPH radical scavenging activity of water extract and reducing power of 80% methanol extract were higher in hot-air and shade-dried GAs than in freeze-dried GA.

• Korean Journal of Plant Resources
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• v.26 no.4
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• pp.433-440
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• 2013

Nine kinds of flowers were selected by its antioxidative activities evaluated. DPPH(1,1-diphenyl-2-picryl hydrazil), reducing power, total phenol contents, total flavonoid contents, and antimicrobial activity inhibitory effects of nine natural flower varieties were examined using ethanol extract (80%, v/v). DPPH radical scavenging of Agastache rugosa (fisch.&Mey.) kuntze ($IC_{50}=74.6{\mu}g/mL$) and solidago virga-aurea var. asiatica ($IC_{50}=99.6{\mu}g/mL$) showed higher antioxidant activity compared with those of the other varieties. Reducing power of Agastache rugosa (fisch.&Mey.) kuntze ($OD_{700}=1.0$) had higher antioxidant activity. Agastache rugosa (fisch.&Mey.) kuntze showed the highest content of total phenol (134.6 mg GAE/g). However, total flavonoid (554.6 mg QE/g) exhibited the lowest. These results suggest that nine kinds of flower with 80% ethanol extracts have significant antioxidant activity.