• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.465-468
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• 2009

The dispersion relation and the characteristic of propagation are measured. The measurements of the dispersion relation are observed by a plunger method employed in slow plasma density by pumping microwaves on the axis are observed in plasma loaded slow wave structure. In case of small incident microwave powers the well known plasma density cavity are observed. At the axial positions of minimal radius in the waveguides, the maxima og the electron density, the plasma potential and the RF electric field are observed in cases of high-power microwaves.

• Korean journal of food and cookery science
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• v.10 no.4
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• pp.357-362
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• 1994

Beef loaves(5${\times}5{\times}$5cm) were cooked by conventional moist-heat and by various levels of microwaves. The mean internal temperature of the meats cooked by low power microwaves for 5~15 min were not significantly different from the conventionally boiled meats for 30 min. When cooking was made by microwaves at low level for 5~10 min, or at high level for 2 min and additional heating at low power level for 5min, the percent cooking loss were comparable with the samples cooked conventionally for 20~40 min. General proteolytic activity determined with azocoll indicated that enzyme activity decreased as internal temperature increased(r=-0.5779, p<0.05), and maximum activity occured at meats conventionally moist-heated for 10 min and by low power microwave for 5 min. Sensory scores for tenderness were high at conventional moist-heat for 30 min, for 20 min, microwave cooked at thatwing power for 10 min and at low power level for 10 min, in descending order. There were no significant differences in the thiamin content of meats after various treatments.

• Journal of the Korean Institute of Telematics and Electronics
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• v.2 no.2
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• pp.2-8
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• 1965

This paper shows the characteristics of microwaves in a plasma medium bounded by a waveguide. A standing wave detector which has VSWR less than 1.05 is designed and constructed. The electromagnetic waves which propagate through the plasma is reflected partly by the interaction between the external magnetic fields and plasma. The plasma is consisted of the electrons and positive ions ionized by high temperature of tungsten filament inserted in the waveguide. The transmitted power through the plasma was reduced by the amount of 1.5db from the reference.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.169-173
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• 2003

In this paper, we present a design and experiment study of high power large diameter backward wave oscillator. Analysis is made within the scope of linear theory of absolute instibility. The Electron beam generator may be atteractive source of high power millimeter microwaves which has simpler structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.287-287
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• 2009

The characteristics of slow wave structure employed for backward wave oscillators expected to be a high power microwave source are studied analytically and experimentary. The slow wave structure is a sinusoidally corrugated wall waveguide The dispersion relationn and transmitted characteristics for microwaves are measured in the air. There exist literatures on high efficiency of enhanced radiation from backward wave oscillators involving plasma studied experimentally.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.597-602
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• 2008

This paper examines the damage effect and delay time of CMOS integrated circuits device with coupling caused by high power microwaves. The waveguide and magnetron was employed to study the influence of high power micro-waves on CMOS inverters. The CMOS inverters were composed of a LED circuit for visual discernment. Also CMOS inverters broken by high power microwave is observed with supply current and delay time. When the power supply current was increased 2.14 times for normal current at 9.9 kV/m, the CMOS inverter was broken by latch-up. Three different types of damage were observed by microscopic analysis: component, onchipwire, and bondwire destruction. Based on the results, CMOS inverters can be applied to database to elucidate the effects of microwaves on electronic equipment.

• Computers and Concrete
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• v.8 no.4
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• pp.425-443
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• 2011

Most previous studies have generally overlooked the contribution of thermal stresses generated within the concrete mass when subjected to microwave heating and reported on pore-pressure as being the dominant cause of surface spalling. Also, the variation in electromagnetic properties of concrete and its effects on the microwave heating process have not been studied in detail. In this paper, finite element modeling is used to examine the simultaneous development of compressive thermal stresses and pore-pressure arising from the microwave heating of concrete. A modified Lambert's Law formulation is proposed to estimate the microwave power dissipation in the concrete mass. Moreover, the effects of frequency and concrete water content on the concrete heating rate and pattern are investigated. Results show high compressive stresses being generated especially in concrete with a high water content when heated by microwaves of higher frequencies. The results also reveal that the water content of concrete plays a crucial role in the microwave heating process.

• Korean journal of food and cookery science
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• v.10 no.4
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• pp.351-356
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• 1994

Comparisions were made for cooking times, internal temperatures, thiamin contents and textural properties of various portion weights of egg mixture cooked in a microwave oven at high and/or low power levels and in a conventional double boiler. The mean internal temperatures of conventionally cooked egg mixtures were 76.4~80.7$^{\circ}C$. When cooking was made by steaming, the mean internal temperature were comparable among samples. With the microwave cooking, the range of mean temperature was 83.8~96.4$^{\circ}C$, and they were significantly higher than the conventionally cooked egg mixtures. The hardness determination was conducted using universal testing machine and a taste panel. Samples cooked with steam or with larger portion weight had softer texture than samples cooked by microwaves or smaller amount, respectively. Mean internal temperature was significantly(r=0.99, p<0.05) correlated with mechanical hardness determination. Statistical analyses indicated no significant difference in the thiamin content among various treatments.

• Journal of electromagnetic engineering and science
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• v.15 no.2
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• pp.82-88
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• 2015

The magnetron, a vacuum tube, is currently the usual high-power microwave power source used for microwave heating. However, the oscillating frequency and output power are unstable and noisy due to the low quality of the high-voltage power supply and low Q of the oscillation circuit. A heating system with enhanced reliability and the capability for control of chemical reactions is desired, because microwave absorption efficiency differs greatly depending on the object being heated. Recent studies on microwave high-efficiency power amplifiers have used harmonic processing techniques, such as class-F and inverse class-F. The present study describes a high-efficiency 100 W GaN-HEMT amplifier that uses a harmonic processing technique that shapes the current and voltage waveforms to improve efficiency. The fabricated GaN power amplifier obtained an output power of 50.4 dBm, a drain efficiency of 72.9%, and a power added efficiency (PAE) of 64.0% at 2.45 GHz for continuous wave operation. A prototype microwave heating system was also developed using this GaN power amplifier. Microwaves totaling 400 W are fed from patch antennas mounted on the top and bottom of the microwave chamber. Preliminary heating experiments with this system have just been initiated.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.461-464
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• 2009

The characteristics of slow wave structure employed for backward wave oscillators expected to be a high power microwave source are studied analyytically. The slow wave structure is a sinusoidally corrugated wall waveguide. The waveguide is designed and fabricated by cast aluminun. The dispersion relation and transmitted characteristics for microwaves are measured in the air. There exist literatures on high efficiency of enhanced radiation from backward wave oscillators involving plasma studied experimentally.