• 한국식품과학회지
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• 제35권2호
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• pp.222-228
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• 2003

팽이버섯 추출물의 수율 및 전자공여작용, 총폴리페놀함량, tyrosinase 저해작용, 갈색도, 아질산염 소거작용에 대하여 반응표면분석에 의해 추출조건을 최적화 하였다. 팽이버섯 추출물의 수율변화는 에탄올 농도에 가장 큰 영향을 받았으며, 갈변도는 microwave power 보다는 에탄올 농도에 크게 영향을 받는 것으로 나타났으며, 아질산염 소거작용의 경우 에탄올 농도가 증가할수록, microwave power가 감소할수록 증가하는 경향을 나타내었다. 전자공여작용의 경우 에탄올 농도가 증가할수록 증가폭이 컸고, microwave가 증가할수록 조금씩 증가하는 경향을 보였다. 총 폴리페놀 함량의 경우 에탄올 농도가 증가할수록, microwave power가 클수록 추출물의 생리활성이 우수한 것으로 나타나 에탄올 농도가 추출시 중요한 공정인자임을 확인 할 수 있었다. 한편, tyrosinase 저해 작용의 경우 에탄올 농도보다는 microwave power에 영향을 받았는데 power가 작을수록 그 값은 크게 측정되었다. 따라서 팽이버섯의 최적 추출조건 범위는 microwave power $47.21{\sim}76.05$ watt, ethanol 농도 $10.25{\sim}43.56%$, 추출시간 5.72분으로 예측되었다.

• 한국수소및신에너지학회논문집
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• 제28권5호
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• pp.577-583
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• 2017

A series of microwave waste tire pyrolysis experiments were conducted using a lab-scale batch reactor to delineate the effects of microwave ouput power on the pyrolysis behavior of waste tire. As results of experiments, it was found that as the microwave output power was increased from 1.22 kW/kg to 2.26 kW/kg, the reaction temperature and oil yield increased significantly and the required time and microwave power consumption decreased remarkably, respectively. With increased power consumption, the content of the fixed carbon of pyrolysis residue increased.

• Journal of electromagnetic engineering and science
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• 제15권2호
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• pp.82-88
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• 2015

The magnetron, a vacuum tube, is currently the usual high-power microwave power source used for microwave heating. However, the oscillating frequency and output power are unstable and noisy due to the low quality of the high-voltage power supply and low Q of the oscillation circuit. A heating system with enhanced reliability and the capability for control of chemical reactions is desired, because microwave absorption efficiency differs greatly depending on the object being heated. Recent studies on microwave high-efficiency power amplifiers have used harmonic processing techniques, such as class-F and inverse class-F. The present study describes a high-efficiency 100 W GaN-HEMT amplifier that uses a harmonic processing technique that shapes the current and voltage waveforms to improve efficiency. The fabricated GaN power amplifier obtained an output power of 50.4 dBm, a drain efficiency of 72.9%, and a power added efficiency (PAE) of 64.0% at 2.45 GHz for continuous wave operation. A prototype microwave heating system was also developed using this GaN power amplifier. Microwaves totaling 400 W are fed from patch antennas mounted on the top and bottom of the microwave chamber. Preliminary heating experiments with this system have just been initiated.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.250-260
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• 2015

Purpose: Dual cylindrical microwave chambers equipped with an ohmic heating tube were designed and fabricated to maximize the electric field strength for expeditious heat treatment of particulate foods. Methods: The efficacy of the combination heater was investigated by simulating the electric field distribution by using COMSOL Multiphysics software. Results: All components of the designed microwave heating unit were suitable for transmitting maximal microwave power to the load. The simulated electric field distribution implied that single-mode microwave heating would be sufficient for the steady generation of a highly localized heating zone in the cavity. During impedance matching, the calculated reflection coefficient ($S_{11}$) was small, possibly implying minimal power loss and wave reflection in the designed microwave heating chamber. Conclusions: This study demonstrates the possibility of concentrating the microwave power at the centerline for a single-frequency microwave, for thermal treatment of multiphase foods without attenuating the microwave power.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권3호
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• pp.180-187
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• 2004

A conventional power supply of a microwave oven has a 60Hz transformer and high voltage capacitor(HVC). Though it is very simple and has low cost, it has several problems such as large size, heavy weight and low efficiency To improve these problems, various high frequency inverter type power supply have been investigated and developed in recent years. But these cost is higher than the conventional one due to additional control circuit, fast switching devces. In this paper, a novel pulse power supply for microwave oven using high frequency transformer embedded HVC(High Voltage Capacitor) is proposed for down-sizing, cost reduction and efficient improvement. To verify the effectiveness of the proposed transformer, an equivalent circuit of transformer embedded HVC is derived and it's characteristic is described. And the validity of the proposed pulse power supply embedded HVC-high frequency transformer is shown by simulations and experiments accroding to various operating conditions.

• 한국식품저장유통학회지
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• 제9권4호
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• pp.385-390
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• 2002

마이크로웨이브 추출(MAE)을 이용하여 만가닥버섯을 물, 50% 에탄올, 99% 에탄올로 추출하였으며 마이크로웨이브의 power와 시간에 따라 추출물의 총 폴리페놀 함량, 전자공여 작용(EDA), tyrosinase 저해작용, 아질산염 소거작용의 차이를 관찰하였다. Microwave power를 60∼120 W로 증가시킴에 따라 총 폴리페놀 함량과 전자공여능은 증가하는 경향을 나타내었다. 만가닥버섯의 전자공여능이 90 W에서 평형에 이른 반면에 tyrosinase 저해능은 90 W 이상에서 급격히 증가하였다. 50% 에탄을 추출물과 99% 에탄을 추출물의 아질산염 소거능은 microwave power를 증가시킴에 따라 확연히 증가하는 경향을 나타내었으며 pH 1.2에서 99% 에탄을 추출물은 물 추출물에 비해 약 5배 정도의 높은 값을 나타내었다. 추출시간에 따른 총 폴리페놀 함량을 살펴본 결과 물 추출물의 경우 추출시간 5분에서 평형에 이르렀다. 전자공 여능은 5∼10분 사이에 급격히 증가하다가 10분에서 평형에 이르렀으며 물 추출물에서 가장 높게 나타내었다. tyrosinase 저해능은 microwave power 증가에 따라 점진적으로 증가하는 경향을 나타내었다.

• 한국식품영양과학회지
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• 제32권4호
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• pp.574-580
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• 2003

만가닥 버섯 추출물의 수율 및 전자공여작용, 총폴리페놀 함량, tyrosinase 저해작용, 갈색도, 아질산염 소거작용에 대하여 반응표면분석에 의해 추출조건을 최적화하였다. 만가닥 버섯의 경우 수율은 에탄올 농도에 가장 큰 영향을 받았으며, 전자공여작용의 경우 에탄올 농도가 높고 microwave power가 높은 조건에서 높은 추출률을 나타내었다. 갈변도 및 tyrosinase 저해작용의 경우 에탄을 농도가 증가할수록 microwave power가 증가할수록 더욱 크게 나타났다. 아질산염 소거 작용의 경우 에탄을 농도와 추출시간의 조건에 크게 영향을 받지 않는 것으로 판단되었으며 총 폴리페놀 함량은 에탄을 농도가 증가할수록 증가폭이 크고, microwave power가 증가할수록 추출물의 생리활성이 우수한 것으로 나타났다. 따라서 만가닥버섯의 최적 추출조건 범위는 microwave power 60.15~102.75 watt, ethanol 농도 53.20~64.01%, 추출시간 7.77분으로 예측되었다.

• 전기학회논문지
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• 제61권10호
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• pp.1477-1482
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• 2012

This paper deals with a new variable microwave power distributor and a connector between a deck plate and a input power waveguide for indoor microwave wireless power transmission. We design a new type connector built in the 3-stage coaxial line structure, and calculate the return loss of the connector at 2.45GHz. Newly designed connector shows the excellent return loss performance less than -30dB at the operating frequency of 2.45GHz. And we show a power distributor in which the dividing ratio of the power is controlled mechanically by three rotary fins. The distributor can control the dividing power from 4.5% to 58% with the variance of 5% output power. The experimentally tested results of the distributor are good agreement with the simulation within the return loss of 1%.

• 전기학회논문지
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• 제62권6호
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• pp.792-797
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• 2013

In a indoor microwave power distribution system, matching-type power dividing switch is proposed and designed with a various power dividing ratio. A matching coaxial cable probe is used behind the output probe for the reflecting power absorption. Reflecting characteristics of the matching coaxial cable probe are calculated by analyzing the S-parameter of this structure. Newly proposed matching-type switch shows a very low return loss less than -30dB at the operating frequency of 2.45GHz with a dividing power ratio of 50.2%. The simulated results by use of 3-stage power divider shows a good agreement with the theoretical estimation for the various combination of the different switching ratio.

• Journal of Biosystems Engineering
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• 제37권6호
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• pp.385-397
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• 2012

Purpose: Drying characteristics of sawdust was studied under batch mode using lab scale microwave dryer. The objective of this study was to investigate the effect of material load and microwave output power on drying characteristics of sawdust. Methods: Material load and microwave output power were varied from 23 to 186 g and 530 to 370 W respectively. Different kinetic models were tested to fit the drying rates of sawdust. Similarly, the activation energy was calculated by employing the Arrhenius equation. Results: The drying efficiency increased considerably, whereas the specific energy consumption significantly decreased with increase in material load and microwave output power. The cumulative energy efficiency increased by 9%, and the specific energy consumption decreased by 8% when the material load was increased from 23 to 186 g. The effective diffusivity increased with decrease in material load and increase in microwave output power. The previously published model gave the best fit for data points with $R^2$ and RMSE values of 0.999 and 0.01, respectively. Conclusions: The data obtained from this study could be used as a basis for modeling of large scale industrial microwave dryers for the pellet production.