• The Magazine of the IEIE
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• v.28 no.10
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• pp.45-55
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• 2001

• Economic and Environmental Geology
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• v.52 no.6
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• pp.595-604
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• 2019

The purpose of this study was simply to obtain gold through a microwave-nitric acid experiment of invisible gold concentrate with the use of filter paper. For the purpose, this study conducted a microwave-nitric acid leaching experiment and examined nitric acid concentration. As a result of the experiment, this study discovered that Fe, Te and Ag were completely leached in the leaching solution whereas Au was not determined in all of the nitric acid conditions. The leaching solution was filtered with three filter papers and then these filter papers were analyzed with SEM/EDS. As a result of the EDS analysis, Au was detected in all of the surface and cross-section of the 1st, 2nd and 3rd filter papers. As the three filter papers containing solid-residue were analysed in the lead-fire assay, gold particles were found in all of the nitric acid conditions. In the lead-fire assay, maximum gold(452.50g/t) was recovered when nitric acid concentration was 6M and microwave leaching time was 12mins.

• Food Science and Preservation
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• v.13 no.6
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• pp.732-739
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• 2006

This study was performed to investigate the changes in quality properties of extract from roasted Pleurotus eryngii by microwave-assisted extraction (MAE). MAE was carried out under different conditions including ethanol concentration, extraction time and microwave power. Total phenolics compound contents, electron donating ability (EDA) and nitrite-scavenging ability at pH 1.2 were high at 50% ethanol concentration. Superoxide dismutase (SOD)-like activity was high at 75% ethanol concentration. Soluble solid and total phenolics compound content decreased as extending extraction time up to 7 min. EDA decreased as increased extraction time. SOD-like activity and nitrite-scavenging ability were not significantly different. The highest soluble solid content, total phenolics compound content and EDA were obtained at 100 W extraction of microwave power. SOD-like activity was high at 25 W. But microwave power did not significantly affect the nitrite-scavenging ability.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.208-214
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• 2020

In this study, the characteristics and mechanism of microwave-assisted drying were investigated to improve the efficiency of the storage and extraction of biomass through the removal of moisture from plant cell Taxus chinensis. The efficiency of microwave-assisted drying increased with increasing microwave power. When the experimental data were fitted to typical drying kinetic models, the page and modified Page models were the most appropriate. The microwave-assisted drying was determined to be a spontaneous endothermic process, and randomness increased during the drying process. The effective diffusion coefficient (3.445 × 10^-9~7.163 × 10^-7 ㎡/s) and mass transfer coefficient (3.1529 × 10^-5~1.2895 × 10^-2 m/s) increased with increasing microwave power. The small Biot number (0.3890~0.7198) indicated that the mass transfer process was externally controlled.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1022-1028
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• 2000

Aster glehni was extracted by microwave-assisted extraction(MAE) and reflux extraction(RE) methods and their extraction efficiencies were compared. A considerable reduction in extraction time was achieved by MAE. When 70% methanol, 50% methanol, 70% ethanol, or 50% ethanol was used, MAE extract contained nearly same amounts of soluble solid and total polyphenol contents as obtained by RE. The optimum MAE conditions for the extraction of Aster glehni were $120{\sim}150$ watts of microwave energy and $4{\sim}8$ minutes of extraction time. No significant changes were found in electron donating ability(EDA) over the variation of microwave energy or extraction time. The use of diluted methanol or ethanol resulted in improving extraction yield(24%), total polyphenol content(2.6%) and EDA(60%).

• Journal of the Mineralogical Society of Korea
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• v.30 no.3
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• pp.103-112
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• 2017

In order to transform arsenopyrite into pyrrhotite and to decrease As content by less than 2,000 mg/kg, pulp sample and non-magnetic pulp sample were heated in a microwave oven at different heating times and were separated through wet-magnetic separation. As the microwave heating time increased, the phase of pyrrhotite was extended to become arsenopyrite entirely. The melting pores and micro-cracks occurred on the pyrrhotite due to hot spot phenomenon with microwave heating. The heated raw pulp sample (As content : 19,970.13 mg/kg) and non-magnetic pulp sample (As content : 19,970.13 mg/kg) which were heated in a microwave oven for 10 minutes were separated through wet-magnetic separation and magnetic fraction containing less than 2,000 mg/kg of As content was recovered only from the heated sample of magnetic separation. It was discovered that for the sulfide complex ore with As penalty imposed on, if microwave heating and wet-magnetic separation are effectively utilized, magnetic fraction. We expect to be able to obtain ore minerals with an arsenic content below the penalty charge.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.216-216
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• 2016

마이크로웨이브를 이용한 플라즈마 소스의 경우 동작 압력 범위가 넓고 전자가열이 효율적이며, 낮은 이온에너지를 갖는 고밀도의 플라즈마를 발생시킬 수 있는 장점이 있어 최근 많은 연구가 되고 있다. 그 중에서 본 연구에 이용된 선형 안테나를 사용하는 마이크로웨이브 플라즈마 장치는 구성이 간단하고, 직 병렬 결합을 통해 고효율, 고밀도의 플라즈마 생성이 가능한 장점이 있다. 본 연구에서는 선형 안테나를 사용하는 마이크로웨이브 플라즈마 소스의 구조에 따른 특성 변화를 2차원 유체 시뮬레이션을 통하여 검증하였다. Maxwell's equation, Continuity equation, Electromagnetic wave equation 등을 이용해 동축관의 유전율과 Gap size에 따른 특성 변화를 관찰하였다. 동축 형태의 도파관을 따라 전달되는 Wave의 파장을 조절하도록 구조를 변화시켜 플라즈마 특성의 변화를 관찰하고 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.131.2-131.2
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• 2015

마이크로웨이브를 이용한 플라즈마는 효율적인 전자가열이 가능하며, 낮은 이온에너지를 가지는 고밀도 플라즈마를 생성시킬 수 있다는 장점이 있다. 최근 산화물 반도체 및 대화면 디스플레이 장치내 소자의 보호막 증착용으로 저온 PECVD (Plasma Enhanced Chemical Vapor Deposition) 공정 및 장치의 필요성에 따라 마이크로웨이브를 이용한 PECVD 장치가 주목 받고 있다. 본 연구에서는 실리콘 나이트라이드 공정 장치 개발을 위한 2차원 시뮬레이션 모델을 완성하였다. Global modeling을 이용하여 확보한 Chemical reaction data에 대한 검증을 하였다. Maxwell's equation, continuity equation, electromagnetic wave equation 등을 이용하여 Microwave의 파워 및 압력에 따른 전자 밀도, 전자 온도등의 플라즈마 변수의 변화를 관찰하였다. 또한 Navier Stokes equation을 추가하여 챔버 내의 Gas flow의 흐름을 고려한 시뮬레이션을 진행하여 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.289-289
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• 2013

CRFP (carbon fiber reinforced plastics)는 탄소섬유 직물에 수지를 함침시켜 만들어지며, 고강도, 고탄성을 지니면서도 가볍고 밀도가 낮기 때문에 항공우주, 스포츠 용품 등 다양한 분야에서 활용되고 있다. 탄소섬유와 수지의 결합력을 증가시키기 위해 사이징, $HNO_3$ 산화, 전기화학적 산화, 플라즈마 처리 등의 다양한 탄소섬유 표면처리 방법이 개발되고 있다. 본 연구에서는 복합재의 강도향상을 위해 탄소섬유 직물을 마이크로웨이브 알곤 플라즈마로 처리하여 강도변화를 관찰하였다. 플라즈마 처리된 직물은 열가소성수지인 CBT와 함침시켜 탄소섬유 복합재로 제조하였다. 그 결과 플라즈마 처리한 복합재의 강도 향상을 확인할 수 있었고, SEM(scanning electron microscope)을 통해 복합재의 표면이 거칠어진 것을 관찰할 수 있었다. 플라즈마로 인해 직물의 표면적이 증가하여 직물의 표면과 수지의 결합력이 증가한 것으로 판단된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.91-92
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• 2011

본 논문에서는 옥내 LED 조명에 대하여 마이크로웨이브센서 기반의 조명 제어에 관한 연구이다. 실내에 설치된 LED 조명제어는 마이크로웨이브센서를 이용하여 옥내 사람의 움직임을 인식하고, 계측된 센서값을 이용하여 조명의 온·오프 및 dimming 제어를 수행하였다. 또한, 실내 환경 데이터를 계측하여 현재의 환경에 적합하도록 LED 조명을 제어하여 사람의 감성에 적합한 감성제어를 제시하고자 한다.