• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.34-39
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• 2017

The recent gradual increase in the energy demand is mostly met by fossil fuel, but the research on and development of new alternative energy sources is drawing much attention due to the limited fossil fuel supply and the greenhouse gas problem. This paper assesses the feasibility of producing fuel energy from a dewatered sewage sludge by microwave-induced pyrolysis with sludge char and graphite receptor. Both receptors produced gas, char, and tar in order from product amount. The gas produced for the sludge char receptor contained mainly hydrogen and methane with a small amount of light hydrocarbons. The graphite receptor generated higher gravimetric tar and generated higher light tar. Through the results, the product gas from the microwave processes of wet sewage sludge might be possible as a fuel energy. But the product gas has to be removed the condensable PAH tars.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.55-59
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• 2001

Pressure-puffing system or extruder has been used to puff rice kernel or rice flour. Most of the study on rice puffing were the effect of process conditions such as moisture content and heating temperature on physical and chemical characteristics of popped rice. The study on mechanism and development of instant puffed rice like popcorn has been limited. Extruded waxy rice pellets were puffed in a microwave oven after drying and conditioning. Extruded pellets were formed with extrusion conditions of $20{\sim}27%$ moisture content, 2.76 MPa $CO_2$ gas injection pressure and 200 rpm screw speed. Under these conditions, puffed waxy rice pellets in microwave oven had low density and soft texture. Density and texture of puffed waxy rice pellet could be optimized by control of moisture content, $CO_2$ gas injection pressure and screw speed that affect significantly when puffing extruded waxy rice pellet.

• Korean Journal of Materials Research
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• v.19 no.4
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• pp.192-197
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• 2009

Carbon nanotubes (CNT) were used as a catalyst support where catalytically active Pd and Pt metal particles decorated the outside of the external CNT walls. In this study, Pd and Pt nanoparticles supported on $HNO_3$-treated CNT were prepared by microwave-assisted heating of the polyol process using $PdCl_2$ and $H_2PtCl_6{\codt}6H_2O$ precursors, respectively, and were then characterized by SEM, TEM, and Raman. Raman spectroscopy showed that the acid treated CNT had a higher intensity ratio of $I_D/I_G$ compared to that of non-treated CNT, indicating the formation of defects or functional groups on CNT after chemical oxidation. Microwave irradiation for total two minutes resulted in the formation of Pd and Pt nanoparticles on the acid treated CNT. The sizes of Pd and Pt nanoparticles were found to be less than 10 nm and 3 nm, respectively. Furthermore, the $SnO_2$ films doped with CNT decorated by Pd and Pt nanoparticles were prepared, and then the $NO_2$ gas response of these sensor films was evaluated under $1{\sim}5\;ppm$ $NO_2$ concentration at $200^{\circ}C$. It was found that the sensing property of the $SnO_2$ film sensor on $NO_2$ gas was greatly improved by the addition of CNT-supported Pd and Pt nanoparticles.

• Resources Recycling
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• v.19 no.1
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• pp.21-26
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• 2010

In order to understand the microwave carbothermic reduction of steelmaking slag to recover Fe, the effects of gas atmosphere and carbon addition on the carbothermic reduction behavior of CaO-$SiO_2$-FeO slag were investigated. It was found that the maximum temperature and the reduction rate were higher in air than in nitrogen atmosphere. In addition, under air atmosphere, the maximum temperature and the reduction rate were increased by increasing the amount of additive carbon. When the carbon equivalent is 5, the maximum temperature reached as high as 1800K and the reduction rate was approximately 90%. As the Carbon equivalent increased further, the maximum temperature and the reduction rate did not change.

• Food Science and Preservation
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• v.13 no.6
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• pp.686-690
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• 2006

Quality properties of legumes (Seoritae and red bean) with soaking of 3% NaCl solution and microwave dying were evaluated. The samples were soaking with 3% NaCl at $25^{\circ}C$ for 6 hr(Seoritae) and 12 hr(red bean). Moisture content of Seoritae and red bean after soaking are 35.8%, and 35.1% respectively. The samples were dried with microwave treatment and cooling with microwave treatment combination secondly to $12{\sim}14%$ for moisture content Hardness of Seoritae was decreased from $12,863g_f$ to $3,309g_f$. There was a difference between varieties on color value. Hardness of cooked rice with ratio of milled rice and legumes(7:3) was $3,165g_f$ which is lower value compared to regular cooked mixed rice. Sensory evaluation of cooked mixed rice showed that treated samples have higher scores on color, flavor, taste, texture and overall acceptability values than those of control.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.5
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• pp.893-901
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• 2015

This study investigated the effects of thawing conditions on physiological activities and quality of peeled garlic. Peeled frozen garlic was analyzed after thawing at low temperature ($4^{\circ}C$), room temperature ($20^{\circ}C$), tap water ($20^{\circ}C$), radio frequency of 27.12 MHz, and 2.45 GHz in a microwave. As a result, the time required to thaw garlic to $0^{\circ}C$ by various thawing methods was shortest at2.45 GHz in a microwave, followed by $20^{\circ}C$ tap water, radio frequency of 27.12 MHz, $20^{\circ}C$, and $4^{\circ}C$. Microwave thawing was faster than other methods, but it resulted in significant non-uniformity of heating. The hardness of peeled garlic significantly decreased upon freeze-thawing, whereas it showed improved hardness upon radio-frequency thawing. Total color difference in garlic increased upon freeze-thawing, and it was not improved by various thawing methods. Antioxidant activities were determined for DPPH radical scavenging ability, SOD-like activity, and reducing power. Total phenolic compounds and flavonoids in garlic extract were measured as $3.222{\pm}0.214{\mu}g$ GAE/g and $0.149{\pm}0.03{\mu}g$ QE/g, respectively. The content of total phenolic compounds was significantly reduced by 2.45 GHz microwave thawing ($1.90{\pm}0.02{\mu}g$ GAE/g); however, flavonoid contents were slightly reduced under freezing and thawing conditions. The DPPH radical scavenging ability of garlic extracts was not affected by thawing methods; however, SOD-like activity and reducing power were slightly reduced by freeze-thawing. These results indicate that physiological activities were not improved by radio-frequency thawing; however, thawing time and maintain hardness were reduced compared with conventional thawing methods.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.256-264
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• 2011

By implementing an analysis on the liquid flame proof agent infiltration of microwave-heated wood under soaking conditions (room temperature soaking, heat soaking), its correlation with wood temperature, and the structure of wood and permeating components after soaking in flame proof agent, which was carried out as basic research in order to improve the fire resistance performance of the wood itself, it is found that the infiltration increases as the microwave heating time increases, while for heat soaking, it is found that high infiltration as well as the stable permeability of flame proof agent is achievable. Also, when the wood temperature is more than $80^{\circ}C$, the infiltration by the flame proof agent increased, and a very even infiltration of flame proof agent was observed, which implies that the liquid flame proof agent has a dependency on temperature change of the wood as a condition to penetrate into the wood. As a result of fine structure analysis, the flame proof agent transfer between cells through pits was considered as a cause to increase the infiltration of flame proof agent, and it is also shown that for heat soaking among the permeating component analysis, as the crystallized flame proof agent around the heartwood and sapwood inner pits increases, the flame proof agent can penetrate into the the heartwood part.

• Korean journal of food and cookery science
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• v.8 no.1
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• pp.15-20
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• 1992

The changes in color of spinach leaves upon blanching in boiling water and by microwave oven were investigated. The noticible changes in color of leaves were observed above $70^{\circ}C$. The values of L (lightness), a (redness) and b (yellowness) were decreased upon blanching. The value of the under surface of leaves was decreased by 2~3 times compared to that of the upper surface. The noticible color changes occured from 15 sec and the absorbance at 432 nm of water increased rapidly from 2 min of blanching in boiling water. Salt (0.5 and 0.9%) decreased the absorbance at 432 nm of water. The changes of L and b of the under surface of leaves upon heating with a microwave oven were less compared with those in boiling water. Based on the color differences of leaves upon blanching in boiling water, the optimum ratio of spinach to water was 1:4 or 1:5.

• Journal of electromagnetic engineering and science
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• v.5 no.3
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• pp.126-131
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• 2005

To increase the efficiency of an applicator during microwave hyperthermia therapy, first, the length from the antenna end to a slot is varied to get the optimal matching of the characteristic impedance at the frequency of 2.45 GHz. Using the electric and thermal constants of biological tissue, we compose a phantom to calculate temperature increment as well as the resonance characteristics and the SAR distributions. The proposed 3-slot sleeve antenna inserted in an applicator plays an effective role in increasing the therapy size in the view of heating performance as electromagnetic energy tends to concentrate on not feed point direction but treatment area. The SAR is then used in combination with a finite difference heat transfer equation to determine the temperature distribution. Also, in order to shorten treatment time and increase therapy size, a square-array structure is suggested and analyzed.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.2
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• pp.40-45
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• 2018

We report Optically-Detected Magnetic Resonance (ODMR) study on Nitrogen-Vacancy (NV) centers in diamond. The experiment can easily be conducted with basic optics and microwave components. A diamond crystal having a high-density NV center is suitable for the ODMR study. The magnetic field dependence of ODMR spectrum allowed us to determine the orientation of the diamond crystal. In addition, we measured the variation of the ODMR spectrum as a function of the excitation laser power. Thermal heating induced by optical absorption caused the monotonic decrease of zero field splitting. The contrast of the ODMR peak, however, increased and, then, began to decrease, indicating the optimal laser power for recording the ODMR spectrum.