• 한국표면공학회지
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• 제45권2호
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• pp.89-94
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• 2012

A study to replace a high temperature thermal carbonization process with microwave plasma process is carried for PAN fiber as a starting material. Near atmospheric pressure microwave plasma (1 Torr~45 Torr) was used to control to get the fiber temperature up to $1,000^{\circ}C$. Even argon is an inert gas, its plasma state include high internal energy particles; ion (15.76 eV) and metastable (11.52 eV). They are very effective to lower the necessary thermal temperature for carbonization of PAN fiber and the resultant thermal budget. The carbonization process was confirmed by both EDS (energy dispersive spectroscopy) of plasma treated fibers and OES (optical emission spectroscopy) during processing step as a real time monitoring tool. The same trend of decreasing oxygen content was observed in both diagnostic methods.

• 생약학회지
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• 제44권2호
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• pp.149-153
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• 2013

The purpose of this study was to develop a new preparation process of ginseng extract with the high concentration of prosapogenin, the specific component in Red ginseng. Chemical transformation from the ginseng saponin glycosides to the prosapogenin was analyzed by the HPLC. The extracts of ginseng leaf and stem were processed at the several treatment conditions of the microwave and vinegar(about 14% acidity). MGLS-20 findings show that the ginseng leaf and stem extracts that had been processed with microwave and vinegar for 20 minutes peaked in the level of ginsenoside $Rg_3$(0.906%). MGLS-25 peaked in the level of ginsenoside $Rg_5$(0.329%) in the ginseng leaf and stem extract processed with microwave and vinegar for 25 minute. And the other kinds of ginseng prosapogenin did not show a higher content.

• 생약학회지
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• 제45권4호
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• pp.320-325
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• 2014

The purpose of this study is to develop a new preparation process of Notoginseng root(Panax notoginseng) extracts having high concentrations of ginsenoside $Rg_3$, $Rg_5$, $Rk_1$ and $Rh_4$, a special component of Red and Black ginseng(Panax ginseng). Chemical transformation from ginseng saponin to prosapogenin was analyzed by the HPLC. Extracts of Notoginseng root was processed under several treatment conditions including microwave and vinegar(about 14% acidity) treatments. Results of those treatments showed that the quantity of ginsenoside $Rg_3$ increased by over 7.6% at 15 minutes of pH 2~4 vinegar and microwave treatments. The results of processing with MPN-15 indicate that the microwave and vinegar(about 14% acidity) processed Notoginseng root extracts that had gone through 15-minute treatments were found to contain the largest amount of ginsenoside $Rg_3$(7.639%), $Rg_5$(6.061%), $Rk_1$(1.516%) and $Rh_4$(1.599). It is thought that such results provide basic information in preparing Notoginseng root extracts with functionality enhanced.

• 한국재료학회지
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• 제24권12호
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• pp.700-703
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• 2014

Calcium phosphate minerals are biologically important because of their application in the fields of orthopaedics and dentistry. Herein we have tried to synthesize calcium phosphate minerals from biowaste clam shells. A simple microwave method was used to synthesize a mixture of calcium phosphate minerals such as hydroxyapatite, tri-calcium phosphate, and monetite. The microwave induces vibration of the dipole ions in the reagent. The heating and rearrangement of ions and atoms occurs during the process. The phases obtained in the final powder were ascertained by X-ray diffraction; the morphology of each sample was checked using a scanning electron microscope. We were able to obtain a mixture of calcium phosphate minerals using the microwave method; the calcined powder showed a brick like morphology, which is different from the rod shape morphology of the hydroxyapatite obtained using the hydrothermal process.

• Korean Chemical Engineering Research
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• 제55권4호
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• pp.574-577
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• 2017

In Indonesia, vetiver oil is one commodity that plays an important role in the country's foreign exchange earnings. Currently, the extraction of essential oil from vetiver still uses conventional methods. Therefore, the aim of this study was to know and verify the kinetics and mechanism of microwave hydrodistillation of vetiver based on two models. In this study, microwave hydrodistillation was used to extract essential oils from vetiver. The extraction was carried out in nine extraction cycles of 20 min to 3 hours. The rate constant, the equilibrium extraction capacity, and the initial extraction rate were calculated using the two models. Kinetics of oil extraction from vetiver by microwave hydrodistillation proved that the extraction process was based on the second-order extraction model. The second-order model was satisfactorily applied, with high coefficients of correlation ($R^2=0.9427$), showing that it well described the process.

• 대한수의학회지
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• 제47권2호
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• pp.203-207
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• 2007

Conventional processing of biological materials including nematode parasites for scanning electron microscopy includes fixation with glutaraldehyde and osmium, followed by dehydration in an ascending grade of ethanol, and finally freeze drying. This procedure takes about 8 to 12 h depending on the characteristics of samples. Microwave irradiation of 2,450 MHz enhance the action of cross-linking fixatives and can greatly accelerate various stages of tissue processing. In this study, samples of nematode parasites, Setaria digitata, were fixed by a combination of conventional chemical fixation and the microwave irradiation during the process. The microwave irradiation was also incorporated in the serial dehydration process with ethanol. The complete procedure from the initial fixation to the completion of dehydration with ethanol was reduced to 1 h with good preservation of the ultrastructural details of the specimens.

• 한국세라믹학회지
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• 제53권6호
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• pp.707-711
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• 2016

A small diameter of SiC fiber mat can produce much higher heat under microwave irradiation than the other types of SiC materials. Fabrication of high strength SiC fiber consists of iodine vapor curing on polycarbosilane precursor and heat treatment process. The curing stage of polycarbosilane fiber was maintained at $150-200^{\circ}C$ in a vacuum condition under the iodine vapor to fabricate a high thermal radiation SiC fiber. The structure and morphology of the fibers were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TG) and scanning electron microscopy (SEM). In this study, the thermal properties of SiC fiber mats under microwave have been analyzed with an IR thermal camera and its image analyzer. The prepared SiC fiber mats radiated high temperature with extremely high heating rate up to $1100^{\circ}C$ in 30 seconds. The fabricated SiC fiber mats were not oxidized after the heat radiation process under the microwave irradiation.

• Korean Chemical Engineering Research
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• 제59권2호
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• pp.260-268
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• 2021

Adsorption is the most promising technology used to adsorb CO2 to reduce its concentration in the atmosphere due to its functional effectiveness. Various porous materials have been extensively synthesized to boost CO2 adsorption efficiency, for example, zeolite. Here, we report the synthesis process of zeolite adsorbent impregnated with amine, combining the benefit of these two substances. We compared conventional heating with microwave-assisted heating by varying concentrations of monoethanolamine in methanol (10% v/v and 40% v/v) as a liquid solution. The results showed that monoethanolamine impregnation helps significantly increase adsorption capacity, where adsorption occurs as a physisorption and not as chemisorption due to the adsorbent's steric hindrance effect. The highest adsorption capacity of 0.3649 mmol CO2 / gram adsorbent was reached by microwave exposure for 10 minutes. This work also reveals that a decrease in CO2 adsorption capacity was observed at a longer exposure period, and it reached a constant 40-minute adsorption rate. Impregnating activated zeolite with 40% monoethanolamine for 10 minutes in addition to microwave exposure (0.8973 mmol CO2 / gram adsorbent) is the maximum adsorption ability achieved.

• 한국식품과학회지
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• 제31권1호
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• pp.54-61
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• 1999

본 연구는 해동 중 발생하는 drip 손실, 미생물의 오염, 표면의 과열 등을 방지하면서 급속 해동 방법을 찾기 위해 동결 돈육에 여러 가지 해동 방법을 적용하였다. 4, 28, $50^{\circ}C$에서의 해동과 2,450, 915 MHz의 microwave를 이용하여 해동을 실시하였고, 915 MHz microwave 해동은 출력을 5, 10, 15 kW로 변화시키면서 단일 조사와 $120^{\circ}C$의 열풍을 함께 조사한 경우를 해동시간, 온도분포, drip 손실, 보수력, 표면색도, 총세균수를 측정하였다. 915 MHz microwave를 이용한 해동은 열전도에 의한 해동보다 2백배 이상 시간이 단축되었고, 2,450 MHz microwave를 이용한 해동 방법의 침투깊이의 제한에서 발생되는 문제를 개선시킬 수 있었으며 drip 손실, 보수력, 총세균수에 있어서 효과가 컸다. 저주파수(915 MHz), 저출력(5 kW)의 microwave와 대류 가열을 병용하여 품질 저하를 최소한으로 방지하면서 급속해동을 위한 산업적 이용이 가능한 것으로 기대할 수 있었다.

• Journal of Forest and Environmental Science
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• 제31권1호
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• pp.1-6
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• 2015

Microwave assisted biodiesel production from crude Pongamia pinnata oil using homogeneous base catalyst (KOH) was unsuccessful because of considerable soap formation. Therefore, a two step process of biodiesel production from high free fatty acid (FFA) oil was investigated. In first step, crude P. pinnata oil was acid catalyzed using $H_2SO_4$ and acid value of oil was reduced to less than 4 mg KOH/g. Effect of sulfuric acid concentration, alcohol-oil molar ratio and microwave irradiation time on acid value of oil was studied. Result suggested that 1.5% $H_2SO_4$ (w/w), 6:1 methanol oil molar ratio and 3 min microwave irradiation time was sufficient to reduce the acid value of oil from 12 and 22 mg KOH/g to 2.9 and 3.9 mg/KOH/g, respectively. Oil obtained after pretreatment was subsequently used for microwave assisted alkali catalyzed transesterification. A higher biodiesel yield (99.0%) was achieved by adopting two step processes. Microwave energy efficiency during alkali catalyzed transesterification was also investigated. The results suggested a significant energy saving because of reduced reaction time under microwave heating.