• Food Science and Biotechnology
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• v.17 no.2
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• pp.379-383
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• 2008

Extraction characteristics of garlic and functional properties of corresponding extract were monitored by response surface methodology (RSM). Maximum extraction yield of 26.41% was obtained at microwave power of 146.29 W, ethanol concentration of 63.31 %, and extraction time of 5.88 min. At microwave power, ethanol concentration, and extraction time of 114.84 W, 58.83%, and 1.42 min, respectively, maximum electron-donating ability (EDA) was 72.86%. Maximum nitrite-scavenging ability was 94.62% at microwave power, ethanol concentration, and extraction time of 81.83 W, 2.65%, and 3.83 min, respectively. Superoxide dismutase (SOD) showed maximum pseudo-activity of 49.12% at microwave power of 34.23 W, ethanol concentration of 33.11 %, and extraction time of 4.40 min. Based on superimposition of 4-dimensional RSM with respect to extraction yield, electron-donating ability, nitrite-scavenging ability, and pseudo-activity of SOD, optimum ranges of extraction conditions were microwave power of 0-100 W, ethanol concentration of 40-70%, and extraction time of 2-8 min.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.8
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• pp.391-397
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• 2002

This paper presents a modeling and simulation of a PI controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm fnr a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the Pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.91-97
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• 2007

This paper presents a pitch angle controller of a grid-connected wind turbine system for extracting maximum power from wind and implements a modeling and simulation of the wind turbine system on MATLAB/Simulink. It discusses the maximum power control algorithm for the wind turbine and presents, in a graphical form, the relationship of wind turbine output, rotor speed, and power coefficient with wind speed when the wind turbine is operated under the maximum power control algorithm. The objective of pitch angle control is to extract maximum power from wind and is achieved by regulating the blade pitch angle during above-rated wind speeds in order to bypass excessive energy in the wind. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction during above-rated wind speeds and effectiveness of the proposed controller would be satisfactory.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.390-395
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• 2012

Response surface methodology was used to monitor the characteristics of Corni fructus. A maximum electron donating ability of 81.27% was obtained at 119.71 W of microwave power, 7.71% of ethanol concentration, and 4.21 min of extraction time. The maximum inhibitory effect on tyrosinase was 105.92% at 143.36 W of microwave power, 58.19% ethanol concentration, and 6.71 min of extraction time. The maximum superoxide dismutase like activity was 87.08% under the extraction conditions of 107.33 W of microwave power, 96.14% ethanol concentration, and 31.49 min of extraction time. The total polyphenol content showed a maximum of 475.86 mg% at 140.29 W of microwave power, 27.44% ethanol concentration, and 58.69 min of extraction time. Based on the superimposition of four-dimensional RSM data regarding the electron-donating ability, inhibitory effect on tyrosinase, superoxide dismutase like activity, and total polyphenol content, the optimum ranges of extraction conditions were found to be at 78~98 W of microwave power, 3~33% ethanol concentration, and 3.6~9 min of extraction time.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.11
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• pp.753-759
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• 2004

This paper presents a modeling and simulation of a fuzzy controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• Advances in Energy Research
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• v.8 no.3
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• pp.185-202
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• 2022

This research work focuses to design and simulate a 200W solar power system with electrical power conservation scheme as well as thermal power conservation modeling to improve power extraction from solar power plant. Many researchers have been already designed and developed different methods to extract maximum power while there were very researches are available on improving solar power thermally and mechanically. Thermal parameters are also important while discussing about maximizing power extraction of any power plant. A specific type of coolant which have very high boiling point is proposed to be use at the bottom surface of solar panel to reduce the temperature of panel in summer. A comparison between different maximum power point tracking (MPPT) technique and proposed MPPT technique is performed. Using this proposed Thermo-electrical MPPT (TE-MPPT) with Deep Learning Algorithm model 40% power is conserved as compared to traditional solar power system models.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2307-2309
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• 2004

This paper presents a modeling and simulation of a fuzzy controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1600-1610
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• 2017

We propose maximum power extraction from a rooftop solar photovoltaic (PV) array during partial shading conditions. Partial shading is unavoidable during power extraction from rooftop PV systems due to nearby tall buildings (construction of additional floors) and trees (growth of trees). Many reconfiguration techniques can be used to extract maximum power in partial shading conditions, but in several cases, the real maximum power output is not achieved. In this study, a new switched PV technique is proposed to enhance the power output. The proposed technique is simple to use and more cost effective than other reconfiguration techniques. Therefore, it is suitable for rooftop applications. The power output of the proposed technique is compared with that of existing techniques with similar shading patterns. Eight panels with ratings of 250 watts (2 kW) each are used for testing. MATLAB simulation and hardware verification are done for the proposed and existing techniques. The proposed technique is implemented on a $4{\times}2$ PV array, although it can be extended to a number of arrays.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1013-1017
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• 2002

Functional activities of Flammulina velutipes extract including electron donating ability, nitrite-scavenging effect, and tyrosinase inhibition activity was examined. Extraction were carried out by microwave-assisted extraction (MAE) under different conditions including solvent and microwave power. Tyrosinase inhibition activity and nitrite-scavenging effect increased as microwave power increased during extraction. Total phenol content and electron-donating ability reached maximum at the microwave power of 90 W. Total polyphenol content and electron-donating ability increased as extraction time extended up to 15 min, with the highest tyrosinase inhibition obtained after 5 min extraction. Significantly higher tyrosinase inhibition activity was found in 99% ethanol extract, whereas greater nitrite-scavenging effect was observed in the water extract. The maximum nitrite-scavenging effect was found at pH 1.2 and decreased as pH increased.

• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.73-79
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• 2011

ORC(organic Rankine cycle) has potential of reducing consumption of fossil fuels and has many favorable characteristics to exploit low-temperature heat sources. This work analyzes performance of ORC with superheating using low-temperature energy sources in the form of sensible energy. Maximum mass flow rate of a working fluid relative to that of a source fluid is considerd to extract maximum power from the sources. Working fluids of R134a, $iC_4H_{10}$ and $C_6C_6$, and source temperatures of $120^{\circ}C$, $200^{\circ}C$ and $300^{\circ}C$ are considered in this work. Results show that for a fixed source temperature thermal efficiency increases with evaporating temperaure, however net work per unit mass of source fluid has a maximum with respect to the evaporating temperature in the range of low source temperature. Results also show that the maximum power extraction is possible with R134a for the source temperature of $120^{\circ}C$, with $iC_4H_{10}$ for $200^{\circ}C$, and with $C_6C_6$ for $300^{\circ}C$.