• Journal of the Korean Wood Science and Technology
• /
• v.37 no.4
• /
• pp.349-356
• /
• 2009

Logs with average diameters of 20~30 cm were dried with microwave to investigate microwave drying characteristic of log and determine the optimal drying conditions. Microwave dryer with output of 20 kW was controlled with respect to the temperature of log during drying. Japanese red pine logs with average diameter of 281.9 mm were dried safely by microwave to below moisture content of 20% within 48 hours. Chinese toon logs showed serious surface checks during microwave drying. Higher drying rates were found with higher initial moisture content.

• Korean Chemical Engineering Research
• /
• v.56 no.5
• /
• pp.773-778
• /
• 2018

In-situ transesterification of microalgae lipids using microwave irradiation has potential to simplify and accelerate biodiesel production, as it minimizes production cost and reaction time by direct transesterification of microalgae into biodiesel with microwave as a heating source. This study was conducted to research the effect of microwave irradiation with in-situ transesterification of microalgae under base catalyst condition. The process variables (reaction time, solvent ratio, microwave power) were studied using 2% of catalyst concentration. The maximum yield of FAME was obtained at about 32.18% at the reaction time of 30 min with biomass-methanol ratio 1:12 (w/v) and microwave power of 450 W. The GC MS analysis obtained that the main component of FAME from microalgal oils (or lipids) was palmitic acid, stearic acid and oleic acid. The results show that microwaves can be used as a heating source to synthesize biodiesel from microalgae in terms of major components resulting.

• Korean Chemical Engineering Research
• /
• v.46 no.4
• /
• pp.752-755
• /
• 2008

Mesoporous SBA-15 silica-supported TsCHDA and TsDPEN ligands have been prepared by reaction of SBA-15 silica with (1R,2R)-N-(trimethoxysilylpropyl-N-sulfonyl)-1,2-cyclohaxanediamine or (1R,2R)-N-(trimethoxysilylpropyl-N-sulfonyl)-1,2-diphenylethylenediamine-1,2-diphenylethylenediamine, respectively. The Ru complexes exhibited excellent catalytic activity and satisfactory enantioselectivity in the asymmetric hydrogen transfer of ketones under microwave conditions. The heterogeneous Ru catalyst was reusable as well as air-stable to allow easy use. Microwave-assisted efficient procedure has been developed for asymmetric hydrogen transfer.

• Journal of the Korean Ceramic Society
• /
• v.48 no.5
• /
• pp.354-359
• /
• 2011

Silicon nitride ceramics were prepared by microwave gas phase reaction sintering. By this method higher density specimens were obtained for short time and at low temperature, compared than ones by conventional pressureless sintering, even though sintering behaviors showed same trend, the relative density of sintered body inverse-exponentially increases with sintering temperature and/or holding time. And grain size of ${\beta}$-phase of the microwave sintered body is bigger than one of the conventional pressureless sintered one. Also they showed good bending strengths and thermal shock resistances.

• Food Science and Preservation
• /
• v.11 no.1
• /
• pp.88-93
• /
• 2004

This study was conducted in order to compare reflux extraction(RE) and microwave-assisted extraction(MAE) in extraction efficiency and establish optimum microwave extraction conditions in obtaining Aster scaber Thunb extracts. Extraction time was reduced considerably in MAE. When 70％ methanol, 50％ methanol, 70％ ethanol, or 50％ ethanol was used, no difference was found in the amount of soluble solid and total phenol between MAE and RE. The optimum microwave-assisted extraction conditions for Aster scaber Thunb were achieved by 120-150 watts of microwave energy and 4∼8 minutes of extraction time. No significant changes were found in antioxidant activity using DPPH scavenging method over the variation of microwave power or extraction time. The use of diluted methanol or ethanol improved soluble solid content(30.8％), total polyphenol content(2.9％) and antioxidant activity(69％ ).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.5
• /
• pp.681-686
• /
• 2012

This study conducted autoclave and microwave treatments on dough to determine if there were any changes in quality after the dough was cooked into bread. Wheat dough after secondary fermentation was treated with a microwave (1 min), an autoclave (30 min), and both an autoclave and microwave (30 min/1 min). We then measured the pH, moisture content, color, texture, and sensory evaluation. The results showed that pH was slightly decreased when it was treated in an autoclave (baking and no baking) and autoclave/microwave (baking and no baking). When microwaved and baked, the moisture content most decreased compared to the control. In crust color, there were no considerable differences in lightness, redness, or yellowness compared to the control, except when microwaved (no baking). The lightness of the crumb color decreased, while redness and yellowness increased, when dough was treated with an autoclave (baking and no baking) and autoclave/microwave (baking and no baking). Hardness, gumminess, chewiness and shear force were significantly increased when dough was treated with an autoclave (baking and no baking) and autoclave/microwave (baking and no baking) compared to the control. In the sensory evaluation, there were no considerable differences in color, aroma, taste, or overall preference when microwaved and baked. Color, aroma, shape, and overall preference were the worst when the dough was treated with autoclave/microwave (baking and no baking). These results suggest that autoclaving and microwaving may reduce the quality of bread, and countermeasures to this problem are necessary.

• Asian-Australasian Journal of Animal Sciences
• /
• v.23 no.3
• /
• pp.347-354
• /
• 2010

This study aimed to evaluate effects of 800 W microwave irradiation for 2, 4 and 6 min on chemical composition, antinutritional factors, ruminal dry matter (DM) and crude protein (CP) degradability, and in vitro CP digestibility of canola seed (CS). Nylon bags of untreated or irradiated CS were suspended in the rumen of three bulls from 0 to 48 h. Protein subfractions of untreated and microwave irradiated CS before and after incubation in the rumen were monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Microwave irradiation had no effect on chemical composition of CS (p>0.05). There was a linear decrease (p<0.001) in the phytic acid and glucosinolate contents of CS as irradiation time increased. Microwave irradiation for 2, 4 and 6 min decreased the phytic acid content of CS by 8.2, 27.6 and 48.6%, respectively. The total glucosinolate contents of CS microwave irradiated for 2, 4 and 6 min decreased by 41.5, 54.7 and 59.0% respectively, compared to untreated samples. The washout fractions of DM and CP and degradation rate of the b fraction of CP decreased linearly (p<0.001) as irradiation time increased. Microwave irradiation for 2, 4 and 6 min decreased effective degradability (ED) of CP at a ruminal outflow rate of 0.05 $h^{-1}$ by 4.7, 12.3 and 21.0%, respectively. Microwave irradiation increased linearly (p<0.001) in vitro CP digestibility of ruminally undegraded CS collected after 16 h incubation. Electrophoresis results showed that napin subunits of untreated CS disappeared completely within the zero incubation period, whereas cruciferin subunits were degraded in the middle of the incubation period (16 h incubation period). In 4 and 6 min microwave irradiated CS, napin subunits were degraded after 4 and 16 h incubation periods, respectively, and cruciferin subunits were not degraded untile 24 h of incubation. In conclusion, it seems that microwave irradiation not only protected CP of CS from ruminal degradation, but also increased in vitro digestibility of CP. Moreover, microwave irradiation was effective in reducing glucosinolate and phytic acid contents of CS.

• Korean Journal of Food Science and Technology
• /
• v.29 no.2
• /
• pp.284-291
• /
• 1997

Microwave vacuum heating method (2450 MHz) was used for a low intensity of heat treatments. High vacuum under the microwave heating could bring low temperature condition. Inactivation of ${\alpha}-amylase,\;{\beta}-amylase$, glucoamylase and peroxidase by microwave vacuum heating were investigated at 60-$80^{\circ}C$. It was compared with conventional heating. The heating condition of microwave vacuum heating was confirmed by the destruction of ascorbic acid. When thermal inactivations of the enzymes by microwave vacuum heating were determined, it was less effective than that of conventional method at the initial stage of heating. It was due to a lag time of microwave heating. However, the heating time for complete inactivation of the enzymes by microwave vacuum heating could be reduced comparing with that of conventional heating. Optimum conditions for inactivation of the enzymes could be obtained by microwave vacuum heating.

• Journal of Chest Surgery
• /
• v.36 no.5
• /
• pp.329-334
• /
• 2003

Backgound: Cryoablation and radiofrequency ablation have been used to treat the atrial fibrillation. Some reports insisted that the microwave ablation Is a better method for a deep and extensive lesion. Material and Method: From December 2001 to July 2002, we peformed 8 microwave ablations in patients who needed mitral valve surgery (7 MVR, 1 MVR+AVR). There were 3 men and 5 women, and their mean age was 43.4$\pm$8.3 years and mean follow up period was 5.6$\pm$2.4 months respectively. The microwave was applied on endocardium or epicardium by Lynx (Afx, inc.) using a power of 45 watts for 25 seconds. We studied the left atrial dimension, the left atrial function and the sinus conversion with echocardiography and electro-cardiography at three times; 1) before the operation, 2) immediately after the operation, and 3) 6 months after the operation. Result: There was no complication and no mortality. The mean aortic clamping time was 104.6$\pm$25.0 minutes, and the mean total bypass time was 130.5$\pm$28.7 minutes. The rate of sinus conversion was 75%, A wave across the mitral valve was a mean of 77.0$\pm$24.8 cm/sec, and the AVE was a mean of 0.46$\pm$0.17 at 5.6 months postoperatively Conclusion: There was no difference in the early result of microwave ablation compared to other methods. The microwave ablation was an acceptable method due to its convenient application especially in beating heart.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.1
• /
• pp.123-127
• /
• 2011

This study was conducted to decrease the microbial hazard in kimchi saline water with microwave plasma sterilization system and to evaluate the inactivation of foodborne pathogens by the microwave plasma sterilization system as a non-thermal treatment. Contamination of coliform, Escherichia coli, and yeasts and molds were detected in the used saline water, and the microbial populations increased as the saline water was reused repeatedly. The $D_{10}$-values of E. coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes by the microwave plasma sterilization system were 0.48, 0.52, and 0.45 cycle, respectively. In addition, the microbial populations of coliform, E. coli, Salmonella spp., total aerobic bacteria, and yeasts and molds in the used kimchi saline water were significantly decreased by treating the saline water using the microwave plasma sterilization system. Therefore, these results suggest that microwave plasma sterilization system can be useful in improving the microbial safety of the used saline water.