• Journal of Power Electronics
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• 제9권1호
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• pp.18-25
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• 2009

Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.

• 한국결정성장학회지
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• 제15권1호
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• pp.10-15
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• 2005

Microwave plasma CVD 다이아몬드/Ti 박막 성장 시 CH₄/H₂ 가스의 유량비율, chuck bias, microwave power 등이 다이아몬드 박막의 구조적 특성과 입자밀도에 미치는 영향에 대하여 조사하였다. 2∼3 CH₄ Vol.% 조건일 때 sp³-결합성의 탄소 neutral 들이 우선적으로 형성되고 sp²-결합성의 탄소 neutral 들이 선택적으로 제거됨에 따라 양질의 다이아몬드 박막을 얻을 수 있었으며, 다이아몬드 입자 증착 기구를 해석하였다. Ti 기판에 걸어준 negative chuck bias가 증가함에 따라 다이아몬드 핵생성이 증진되어 다이아몬드 입자 밀도가 증가하였고, 임계 전압은 약 -50V 임을 확인하였다. 또한, microwave power가 증가함에 따라 미세결정질(micro-crystalline) graphite 층 생성이 제어되고 다이아몬드 층이 형성됨을 확인하였다.

• 농업과학연구
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• 제45권4호
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• pp.847-857
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• 2018

Recently, customers' demand and attention to dried agricultural products or foods have increased due to their convenience and nutritional values. Conventional drying methods such as solar drying and hot air drying have been most widely used for producing a large amount of dried agricultural products; however, those methods require quite a long time and high energy consumption. To compensate for these issues associated with conventional methods, dielectric heating such as microwave and radio frequency heating has been used as a supplemental method in the drying procedure. This study investigated the microwave drying characteristics of squash slices with different thicknesses under different microwave power intensities and determined the best drying model that could precisely describe the experimental drying curves of the squash slices. The squash was cut into slices with two different thicknesses (5 and 10 mm), and then, they were dried under different microwave power intensity ranges between 90 and 900 W with an increase interval of 90 W. Six drying models were tested to evaluate the fit to the experimental drying data, and the effective moisture diffusivity ($D_{eff}$) values of the squash slices under microwave drying were determined. The results clearly show that as the microwave power was increased, the drying time of both squash slices was significantly decreased, and the slope of the drying rate increased. The effective moisture diffusivity was also significantly related with the microwave power intensities and thicknesses of the slices. In addition, the Page model was most suitable to delineate the drying curves of both squash slices under different microwave power intensities.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.498-498
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• 2013

Atmospheric Pressure Plasmas have pioneered a new field of plasma for biomedical application bridging plasma physics and biology. Biological and medical applications of plasmas have attracted considerable attention due to promising applications in medicine such as electro-surgery, dentistry, skin care and sterilization of heat-sensitive medical instruments [1]. Traditional approaches using electronic devices have limits in heating, high voltage shock, and high current shock for patients. It is a great demand for plasma medical industrial acceptance that the plasma generation device should be compact, inexpensive, and safe for patients. Microwave-excited micro-plasma has the highest feasibility compared with other types of plasma sources since it has the advantages of low power, low voltage, safety from high-voltage shock, electromagnetic compatibility, and long lifetime due to the low energy of striking ions [2]. Recent experiment [2] shows three-log reduction within 180-s treatment of S. mutans with a low-power palm-size microwave power module for biomedical application. Experiments using microwave plasma are discussed. This low-power palm-size microwave power module board includes a power amplifier (PA) chip, a phase locked loop (PLL) chip, and an impedance matching network. As it has been a success, more compact-size module is needed for the portability of microwave devices and for the various medical applications of microwave plasma source. For the plasma generator, a 1.35-GHz coaxial transmission line resonator (CTLR) [3] is used. The way of reducing the size and enhancing the performances of the module is examined.

• 농약과학회지
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• 제4권3호
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• pp.60-67
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• 2000

건조된 한약재 시료인 백삼, 홍삼, 지황, 당귀 및 시호 중에 잔류되어 있는 tolclofos-methyl 및 quintozene의 추출에 microwave 추출법을 이용하고자 Soxhlet 추출법과 추출효율을 비교하여 최적의 추출용매, 추출시간 및 power supply의 강도 등에 대하여 조사하였다. 다섯 가지 한약재 시료에 잔류되어 있는 tolclofos-methyl 및 quintozene을 microwave로 추출하기 위한 용매는 acetone이 가장 효율적이었다. 추출효율은 Soxhlet 7시간 추출과 microwave로 45 watts에서 1분에서 10분 동안 추출한 결과를 비교하였는데 microwave 추출시간을 $3{\sim}5$분으로 한 결과와 Soxhlet 법으로 7시간 추출한 결과는 거의 같게 나타났다. 시료의 종류에 따른 microwave의 추출특성은 인삼은 5분, 다른 한약재들은 3분의 추출에서 Soxhlet추출과 거의 같은 추출 효율을 나타내었다. 잔류분석시 불순물의 방해를 고려한 최적 추출효율을 나타내는 microwave power는 $45{\sim}90$watts로 나타났다. 따라서 tolclofos-methyl 및 quintozene이 잔류되어 있는 다섯 가지 한약재 시료에서의 microwave를 이용한 추출의 최적 조건은 power $45{\sim}90$ watts, 추출용매 acetone, 추출시간 $3{\sim}5$분인 것으로 나타났다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권2호
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• pp.73-79
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• 2004

For the global microwave market, high RF power or deluxe model is applying for inverter gradually. In this paper, 120[V]/1200[W] high power inverter is proposed and verified by an optimized design of PFM type. Especially the steady power output control was fulfilling at ＋/－ 10[％] input voltage variation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.471-474
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• 2008

The pyrolytic behavior of waste tire under microwave heating was investigated. Experiments were conducted using a lab- and bench-scale system to delineate the effects of microwave output power on the response. As the results of experiments, it was found that as the microwave output power was increased between 0.84 and 3.04 kW/kg, the oil yield and required time rapidly increased and decreased, respectively. With further increase of the microwave output power, the oil yield and required time did not change significantly.

• 한국전자통신학회논문지
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• 제10권3호
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• pp.333-340
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• 2015

본 논문에서는 마이크로파 라디오미터의 기술을 응용한 수동형 마이크로파 인체 감지 센서를 제안한다. 제안된 센서는 고정된 배경 물체로부터 수신되는 복사전력의 인체에 의한 미약한 변화를 측정하여 감시 공간내의 인체를 감지한다. C-band 마이크로파 라디오미터를 설계 제작하여 인체에 의한 수신 복사전력의 변화를 측정하고 그 결과를 분석하여 제안한 센서의 유효성을 평가한다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1172-1177
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• 2004

This paper describes a output power control of magnetron for microwave oven. Magnetron is used extensively in household microwave oven and industrial microwave heating devices it is operated by 3000[V]～5000[V] dc high voltage. Power supply for driving magnetron is consisted of a bridge rectifier. HB(half bridge) inverter, full wave rectifier and gate drive circuit. In proposed system. we confirm that line input power can be controlled extensively and linearly to 24.56[%] by change of duty ratio of inverter through a experiment.

• 한국식품저장유통학회지
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• 제12권4호
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• pp.344-349
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• 2005

섬백리향의 항산화 기능성 성분에 대한 마이크로웨이브 추출특성을 확인하고자 microwave power($0{\sim}160\;W$)와 추출시간($1{\sim}5$분)을 독립변수($X_i$)로 하여 중심합성계획에 의해 10개구간의 추출조건을 설계하였다. 또한 추출물의 기능성분인 총 추출수율, 총 페놀 함량, 총 플라보노이드 함량 및 전자공여능을 종속변수($Y_n$)로 하여 반응표면분석을 실시하여 최적 추출조건을 예측하였다. 도출된 회귀식의 $R^2$는 총 페놀성분을 제외하고는 모두 0.93 이상을 나타내었으며, microwave power는 추출시간보다 영향이 큰 것으로 나타났다(p<0.05). 종속변수들의 최적 추출시간은 $3.36{\sim}4.97$분이었으나 microwave power는 넓은 분포를 보였으며, 기능성 성분들 모두를 추출하기 위한 추출조건 범위는microwave power $64{\sim}100\;W$, 추출시간 $2.9{\sim}4.0$분으로 나타났다.