• 한국연소학회지
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• 제21권2호
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• pp.22-28
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• 2016

High efficient and environment friendly combustion technologies are used to be operated an extreme condition, which results in unintended flame instability such as extinction and oscillation. The use of electromagnetic energy is one of methods to enhance the combustion stability and a microwave as electromagnetic wave is receiving increased attention recently because of its high performance and low-cost system. In this study, an experiment was performed with jet diffusion flames induced by microwave. Micro jet was introduced to simulate the high velocity of industrial combustor. The results show that micro jet flames had three different modes with increasing oxidizer velocity; attached yellow flame, lifted flame, and lifted partially premixed flame. As a microwave was induced to flames, the overall flame stability and blowout limit were extended with the higher microwave power. Especially the interaction between a flame and a microwave was shown clearly in the partially premixed flame, in which the lift-off height decreased and NOx emission measured in post flame region increased with increasing microwave power. It might be attributed to increase of reactivity due to the abundance of radical pool and the enhanced absorption to thermal energy.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.22-26
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• 2016

In this paper, we measured the efficiency of the receiver for 5.8GHz Microwave Smartphone Charging. We have designed and fabricated 1W and 2W power amplifier, respectively. A 1W power amplifier used a TC3531 power device of TRANSCOM Inc. In addition, a 2W power amplifier using the two TC3531 devices was constructed with divider and combiner. We used the Wilkinson divider theory for divider and combiner. The voltage was measured using the 1W and 2W power amplifier and integrated receivers to the distance of 50cm.

• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.88-93
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• 2018

Radio frequency (RF) and microwave power is one of the key quantities in the framework of electromagnetic measurement standards. Therefore, the stability of the power standard is essential to users' reliable measurements in various areas. Coaxial and waveguide thermistor mounts are used as transfer standards of RF and microwave power. Over decades, the effective efficiencies of thermistor mounts have been measured using coaxial and waveguide microcalorimeters in the frequency range of 10 MHz-40 GHz. The measurement uncertainty of the effective efficiency is evaluated. Results show that the power standards have been well maintained within the measurement uncertainty.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.281-282
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• 2010

The microwave power supply is mainly composed of the cathode power supply supplying the beam voltage and beam current of the gyrotron and body power supply for the single depressed collector (SDC) operation, which requires the cathode voltage/current of 80 kV/24 A for the cathode and +24 kV for the body. This paper is describing the power supply system for the gyrotron of KSTAR.

• 동력기계공학회지
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• 제13권3호
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• pp.53-58
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• 2009

The importance of cost reduction has grown bigger to ensure the competetive power of products in the electric home appliances industry. Thus, it is necessary to assess the reliability due to drop-impact happenning in process of distribution of microwave ovens with the panel and cavity of thinner thickness for cost reduction. In the present study, the drop/impact simulation using the explicit code LS-DYNA3D has been carried out for improving the impact resistance of a microwave oven. This CAE-based design approach can be successfully applied to enhance the deteriorated dynamic behavior under the impact conditions of dropping height 70cm according to ISTA procedure 2A.

• 전력전자학회논문지
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• 제22권5호
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• pp.463-468
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• 2017

One of the most critical part for magnetron driving in microwave oven is start-up control. For this, switching frequency of resonant inverter should be carefully controlled in order to supply sufficient power to the filament of the magnetron and to prevent rectifier diode from destruction caused by the excessive voltage across them. This paper proposes a novel start-up control strategy for LLC resonant inverter for microwave oven considering the non-oscillation mode time and the magnetron voltage during the start-up process. The validity of the proposed method is verified through the experiment with 1,200W microwave oven using LLC resonant inverter.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.2029-2033
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• 2007

Hydrotalcite, layered double hydroxides (LDH), with hexagonal morphology has been rapidly synthesized by microwave reaction within 1 hour by urea hydrolysis from homogeneous solution. Different synthesis parameters, Mg/Al molar ratio, microwave reaction temperature and microwave power were systematically investigated. Pure hydrotalcite phase was obtained for Mg/Al ratios of 2:1 and 3:1, and higher reaction temperature gave higher crystallinity. The hydrotalcite synthesized at 600W power shows the highest crystallinity and more homogeneous crystal size distribution. The hydrotalcite samples were characterized by powder X-ray diffraction (XRD), simultaneous thermogravimetric/differential thermal analysis (TG/DTA), Fourier Transform Infrared (FT-IR) and Scanning electron micrograph (SEM).

• 전기학회논문지P
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• 제58권4호
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• pp.588-591
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• 2009

We had experimental studies of microwave output generator. We experimented with a corrugate-shped K-band slow wave guide in the backward wave oscillator. It generated output 표 interaction between electron beam's generation and magnetic field. We estimated oscillation frequency at 24GHz by changing propagation velocity and group velocity. We identified movement by second harmonic of Cherencov interaction and slow cyclotron mode. In our study we achieved oscillation stabilization, generation of long pulse, improvement of oscillation efficiency and output.

• 전기학회논문지P
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• 제58권4호
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.881-885
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• 2008

Wireless energy transmission system to a Micro Aerial Vehicle is now under development. A 5.8 GHz microwave phased array antenna and rectenna array receiver have been developed. An electric motor on a circling MAV model was driven by the transmitted power. In addition, 140GHz millimeter-waves of up to 1MW was beamed to a "Microwave Rocket" and its thrusting has been successfully demonstrated.