• Advances in materials Research
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• 제2권3호
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• pp.133-140
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• 2013

This paper aims to focus on the microwave processing of thick films which is a fast, cheap technique and could be the alternative to the currently used conventional high temperature processing technique. Microwave processing has gained worldwide acceptance as a novel method for heating and sintering a variety of materials, as it offers specific advantages in terms of speed, energy efficiency, process simplicity, finer microstructures and lower environmental hazards. Silver conducting thick films were prepared and processed in the household microwave oven. The films sintered at different time period by keeping the other parameter such as microwave power, film thickness etc constant. The microstructure analysis revealed that the surface morphology of the microwave processed films become compact with respect to the processing time. The sheet resistance for microwave sintered silver films is in the range of 0.003 to $1.207{\Omega}/{\Box}$ where as the films fired at 750 and $850^{\circ}C$ showed the resistance of 0.009 and $0.003{\Omega}/{\Box}$ which can be comparable. The results revealed that the microstructure of the microwave sintered films has more uniform and compact surface than that of the conventionally fired films. The paper reports upon the preparation of silver thick film by screen printing technique and processing the same by microwave which also compared with the conventionally processed thick films.

• 한국산림과학회지
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• 제86권4호
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• pp.502-508
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• 1997

본 연구에서는 수입외재의 국산재대체를 위해 전 국토에 널리 분포하고있는 아까시나무(Robinia pseudo-acacia L.)와 서어나무(Carpinus laxiflora Bl.)를 대상으로, 곡목가구재(曲木家具材)로서의 용도개발가능성을 검토하기 위하여 목재의 함수율 증가에 따른 휨가공특성의 변화를 구명함으로써 microwave곡목의 적용가능성을 타진하는 데 그 목적을 두었으며 얻어진 결과를 요약하면 다음과 같다. microwave곡목제조시 목재함수율이 증가할수록 아까시나무와 서어나무 모두 최소곡율반경(最小曲率半經)이 감소하므로서 휨가공성이 개선되었으며, 아까시나무와 서어나무의 휨가공성에 영향하는 목재의 임계함수율은 50%로 측정되었다. 또한 microwave곡목법에 의한 아까시나무와 서어나무의 휨가공성능은 생재휨가공시 최소곡률반경이 각각 60mm와 40mm로서 매우 우수하였다.

• 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.

• 폴리머
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• 제25권5호
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• pp.609-616
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• 2001

본 연구에서는 copper phthalocyanine (CUPc)을 높은 합성 수율로서 성공적으로 합성시킴에 따라 용매를 사용하는 고분자의 합성 분야에 마이크로파 기술의 응용 가능성을 제시하고자 하였다. 가정용 전자레인지의 용기를 개조시키고 마이크로파 출력 조절기를 부착시키는 방법으로 본 실험에 사용되는 가변식 마이크로파 합성 장치를 자체 제작하였다. 화학 분석법, X선 회절장치(XRD), 주사형 전자현미경 (SEM) 및 입도 분석법 (PSA)을 이용하여 재래식 열 공정 및 마이크로파 공정을 사용하여 여러 조건하에서 합성된 시료들의 특성을 비교 분석하였다.

• 한국광물학회지
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• 제21권2호
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• pp.193-200
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• 2008

배연탈황석고 및 인산부산석고에 함유된 부착수분을 마이크로파에 의한 직접 내부 가열 방법으로 증발시켜 건조하고자 하였다. 700 W, 1,000 W, 1,700 W의 출력인 마그네트론에서 발생된 2.45 GHz의 마이크로파로 배연탈황석고와 인산부산석고를 가열한 결과, 마이크로파 출력의 세기를 700 W에서 1,700 W로 높임에 따라 부착수의 증발시간이 10분에서 3분으로 단축되었고, 이수석고는 베타형 반수석고로 변질되었다. 그러나 베타형 반수석고는 무수석고로 변질되지 않았다.

• Journal of the Korean Wood Science and Technology
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• 제25권2호
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• pp.52-60
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• 1997

Hornbeam trees(Carpinus laxiflora BL.) are growing in Korea and have good characteristics such as relatively high density, fine texture, split- resistance, and white colour. However, they have seldom been used as manufacturing materials This study was carried out to evaluate the possibility of using hornbeam wood as bent, wood furniture materials. Softening methods were steaming and micro-wave heating. The specimens of $15{\times}15{\times}350mm$ were used green or air-dried, and were steamed at $100^{\circ}C$ for 20min, or microwave heat ed f or 60 seconds. The bending processing conditions are showed in Table 3. The minimum solid-bending radii of air-dried wood were 40mm for steaming and 200mm for micro-wave heating, respectively. And that of green wood were 40mm for micro-wave heating. In conclusion, both of the steamed wood and micro-wave heated green wood showed very good solid bending processing properties, but micro-wave heated air-dried wood were not sufficient for bent-wood furniture.

• Journal of the Korean Wood Science and Technology
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• 제11권2호
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• pp.52-60
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• 1983

Hornbeam trees(Carpinus laxiflora BL.) are growing in Korea and have good characteristics such as relatively high density, fine texture, split-resistance, and white colour. However, they have seldom been used as manufacturing materials This study was carried out to evaluate the possibility of using hornbeam wood as bent-wood furniture materials. Softening methods were steaming and micro-wave heating. The specimens of $15{\times}15{\times}350mm$ were used green or air-dried, and were steamed at $100^{\circ}C$ for 20min, or microwave heated for 60 seconds. The bending processing conditions are showed in Table 3. The minimum solid-bending radii of air-dried wood were 40mm for steaming and 200mm for micro-wave heating, respectively. And that of green wood were 40mm for micro-wave heating. In conclusion, both of the steamed wood and micro-wave heated green wood showed very good solid bending processing properties, but micro-wave heated air-dried wood were not sufficient for bent-wood furniture.

• 대한본초학회지
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• 제37권4호
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• pp.17-29
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• 2022

Objective : The present study comparatively analyzed the anti-obesity effect of Arctium lappa L. roots with and without microwave processing. Methods : Four HFD groups except for the Normal group (n=8) were allocated: Control, microwave-processed dried Arctium lappa L. roots (MAL) extract 400 mg/kg/d (MAL400), MAL extract 800 mg/kg/d (MAL800), and the dried Arctium lappa L. roots (DAL) extract 800 mg/kg/d (DAL800). The efficacy of MAL and DAL was confirmed in terms of the serum biochemical index, protein expressions related to the synthesis of triglyceride (TG) and total cholesterol (TC) and 𝛽-oxidation, and histopathological staining. Results : Both MAL and DAL treatments significantly reduced final body weight and body weight gain. MAL800 treatment significantly reduced serum TG, TC, low-density lipoprotein cholesterol, and leptin levels, but the serum high-density lipoprotein cholesterol and adiponectin concentrations were dramatically increased. In particular, leptin in the MAL800 group was reduced by 14.1% compared with the DAL800 group. Moreover, the MAL800 treatment showed an effect superior to the DAL800 treatment in the reduction of serum TC, the sirtuin 1 (Sirt1) activation, and the inhibition of 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGCR) gene expression. In particular, unlike the DAL800 treatment, MAL treatment significantly led to the activation of peroxisome proliferator-activated receptor alpha (PPAR𝛼). Subsequently, PPAR𝛼 meaningfully regulated downstream proteins associated with 𝛽-oxidation. Conclusion : These findings suggest that Arctium lappa L. roots with microwave processing effectively ameliorate obesity through the regulation of leptin and TC and the promotion of 𝛽-oxidation compared with Arctium lappa L. roots without microwave processing.

• 한국축산식품학회지
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• 제34권5호
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• pp.597-603
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• 2014

In this study, the physicochemical and sensory quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen pork were examined. The packaged pork samples, which were frozen by air blast freezing at $-45^{\circ}C$ or electro-magnetic freezing at $-55^{\circ}C$, were thawed using 4 different methods: refrigeration ($4{\pm}1^{\circ}C$), room temperature (RT, $25^{\circ}C$), cold water ($15^{\circ}C$), and microwave (2450 MHz). Analyses were carried out to determine the drip and cooking loss, water holding capacity (WHC), moisture content and sensory evaluation. Frozen pork thawed in a microwave indicated relatively less thawing loss (0.63-1.24%) than the other thawing methods (0.68-1.38%). The cooking loss after electro-magnetic freezing indicated 37.4% by microwave thawing, compared with 32.9% by refrigeration, 36.5% by RT, and 37.2% by cold water in ham. The thawing of samples frozen by electro-magnetic freezing showed no significant differences between the methods used, while the moisture content was higher in belly thawed by microwave (62.0%) after electro-magnetic freezing than refrigeration (54.8%), RT (61.3%), and cold water (61.1%). The highest overall acceptability was shown for microwave thawing after electro-magnetic freezing but there were no significant differences compared to that of the other samples.

• 한국광학회:학술대회논문집
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• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
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• pp.116-117
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• 1999

Optical fiber networks for microwave signal processing have been investigation . Theoretical and experimental results are presented in Z-shaped Double-Coupler Optical Resonator. The use of Mason's rule to calculate transfer functions greatly simplified the analysis in our model. A good comparison between modelling and experiment is presented.