• 신재생에너지
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• 제9권2호
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• pp.5-14
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• 2013

The efficiency of microwave-assisted acid hydrolysis of seaweeds for the production of ethanol was investigated and its effect on hydrolysis into reducing sugar and fermentation into ethanol evaluated as compared with those by conventional heating. A brown seaweed, Laminaria japonica (10-100g/L) was hydrolysed under dilute acidic condition (0.5N $H_2SO_4$, $100^{\circ}C$) with two sorts of heating: microwave irradiation for ${\leq}10min$ and conventional heating for 10-60min. Microwave-assisted hydrolysis was shown to be more efficient. A similar range of reducing sugar and ethanol yields as with the conventional autoclave heating procedure(${\geq}30min$) was observed, but it was obvious that production of ethanol from microwave-assisted hydrolysis had a 3 times faster reaction rate leading to very short production times, lower energy consumption/loss than from the conventional heating mode, and higher biomass loading without significant reducing ethanol yield, thus microwave-assisted acid hydrolysis is a potential alternative method for more effective hydrolysis of Laminaria japonica.

• Transactions on Electrical and Electronic Materials
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• 제10권3호
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• pp.102-105
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• 2009

$Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode materials have been synthesized by a microwave-assisted sol-gel method. The structure and electrochemical properties of $Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ were studied by X-ray difftactometry (XRD), scanning electron microscopy (SEM) and charge-discharge cycler. The powder prepared by microwave assisted sol-gel method showed good crystallinity and well-defined facet shapes. The $Li[Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ electrode delivered a high discharge capacity of 230 $mAhg^{-1}$ at the specific current of 40 $mAg^{-1}$ (0.2 C rate) in the voltage range of 2.0${\sim}$4.8 V. About 60 % of the discharge capacity measured at 0.2 Crate (140 $mAhg^{-1}$) was maintained at a 6 C (1200 $mAg^{-1}$)rate. The cyclic property was also stable and it did not deteriorated at a high Crate.

• 센서학회지
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• 제5권1호
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• pp.9-14
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• 1996

$WO_{3}$가 첨가된 $BaTiO_{3}$를 고상법으로 제작하여 상온에서 $160^{\circ}C$의 온도 범위와 300 kHz - 300 MHz의 주파수 범위에서 회로망분석기를 이용하여 2포트 S-파라메터 방법으로 고주파 저항, 리액턴스 및 임피던스를 측정하여 $130^{\circ}C$ 이하에서 주파수 및 온도센서로서의 가능성을 진단하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.744-749
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• 2005

This paper describes the performance improvement of power control system of magnetron (MGT) for microwave oven. The MGT is used extensively in household microwave oven and industrial microwave heating devices, and is operated by 3.0[kV] $\∼$5.0[kV] dc high voltage. The proposed power supply is consisted of a bridge rectifier, step-up converter(SUC) and its controller, half bridge inverter(HBI) and its controller, and full wave double voltage rectifier(DVR). In the proposed system, a good power factor can be obtained by the SUC' switching method that the inductor current waveforms follows that of the rectified voltage, and a line input power can be controlled to a range of 17.5[$\%$] by duty ratio (DR) adjustment of the HBI.

• 한국세라믹학회지
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• 제42권7호
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• pp.449-454
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• 2005

A waveguide method is developed to study the materials with relatively large dielectric constants at microwave range. Basically, the method is similar to the previous waveguide methods represented by short-circuit line and transmission/reflection measurement methods. However, the complex permittivity is not determined by the shift in resonance frequencies, but by numerical analysis of measured scattering parameters. In order to enhance microwave penetration into the specimen with relatively large permittivity, a dielectric plate with lower permittivity is employed for impedance matching. The influences of air gap between the specimen and waveguide wall are evaluated, and the corresponding errors are estimated. The propagation of higher order modes is also considered. Experimental results for several reference ceramics are presented.

• 천문학회지
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• 제38권4호
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• pp.445-462
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• 2005

In a companion paper, we have presented so-called Spatio-Spectral Maximum Entropy Method (SSMEM) particularly designed for Fourier-Transform imaging over a wide spectral range. The SSMEM allows simultaneous acquisition of both spectral and spatial information and we consider it most suitable for imaging spectroscopy of solar microwave emission. In this paper, we run the SSMEM for a realistic model of solar microwave radiation and a model array resembling the Owens Valley Solar Array in order to identify and resolve possible issues in the application of the SSMEM to solar microwave imaging spectroscopy. We mainly concern ourselves with issues as to how the frequency dependent noise in the data and frequency-dependent variations of source size and background flux will affect the result of imaging spectroscopy under the SSMEM. We also test the capability of the SSMEM against other conventional techniques, CLEAN and MEM.

• 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.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.371-376
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• 2009

Microwave digestion is a preferred pretreatment method for agricultural samples because of its quick chemical reaction and minimum loss of analytes. In this research, a feedback temperature controller was developed to control the temperature inside a vessel for the microwave-assisted digestion system. An existing industrial microwave oven was fitted with the temperature controller for controlling inside temperature of the vessel. Four control methods, On/Off, proportional (P), proportional integral (PI), and proportional integral derivative (PID) were used and compared. Experimental results showed that PID control produced best temperature control performance. The PID controller could maintain the temperature of water sample and rice sample in the digestion system with error range of $-2.5{\sim}3.3^{\circ}C$ and $-1.9{\sim}0.5^{\circ}C$ at set temperature of $170^{\circ}C$, respectively.

• 한국자기학회지
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• 제11권3호
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• pp.109-113
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• 2001

Presently, an inductor adapted at MMIC (Monolithic Microwave Integrated Circuit) which is used for cellular phone or PHS operates at quasi-microwave range over 800 MHz. However, a W-CDMA (Wideband Code Division Multiple Access) will use about 2 GHz range. Therefore magnetic film device should be compatible up to 2 GHz. We have deposited Co-Pd-Al-O system film using rf sputtering method which is expected up to 2 GHz, and investigated the effect of Pd content and magnetic field annealing. When Pd composition is 19%, Hk was 118 Oe, and ${\mu}$′showed flat frequency characteristics up to 1.5 GHz. The Q factor (=${\mu}$′/${\mu}$") was 23.3 at 1 GHz, 6.7 at 1.5 GHz and 1.5 at 2 GHz, respectively. Resonance frequency was 2 GHz. Therefore Co-Pd-Al-O thin film could be used at over 1 GHz, and also expected as an inductor material for wide band CDMA type cellular phone.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.180-180
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• 2012

A microplasma system source based on microwave parallel stripline resonator (MPSR) was developed for the generation of microplasmas in a wide range of pressure from some torr to 760 torr. This source was operated at its resonance frequency that much depends upon not only its discharge gap size but also operated pressure. This paper applied a simple circuit model to analyze the effects of discharge gap size and pressure to resonance frequency and impedance of MPSR in the cases with and without plasma exist inside the discharge gap. In the process of calculating, the conformal mapping method was used to estimate the capacitance of the MPSR. The calculating results by using circuit model agree well with the simulation results that using commercial CST microwave studio software.