• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.695-700
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• 2018

This paper presents the development of compact and lightweight broadband power amplifier module using HMIC (Hybrid Microwave Integrated Circuit) technology that could be high-density integration for many non-packaged microwave components into the small area of a high dielectric constant printed circuit board, such as a ceramic substrate, also using the special design and fabrication schemes for the structure of minimized electromagnetic interference to obtain the homogeneous electrical performance at the wideband frequency. The results confirmed that the small signal gain has a gain flatness of ${\pm}1.5dB$ within the range of 32 to 36 dB. In addition, the output power satisfied more than 30 dBm. The noise figure was measured within 7 dB, and OIP3 (Output Third Order Intercept Point) was more than 39 dBm. The fabricated broadband power amplifier satisfied the target specification required to electrically drive the high power amplifiers of jamming generators for electronic warfare, so the actual applicability to the system was verified. Future studies will be aimed at designing other similar microwave power amplifiers in the future.

• Journal of the Korean Institute of Telematics and Electronics
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• v.5 no.3
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• pp.31-39
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• 1968

In this paper microwave power propagated through the cold plasma was analyzed and measured with respect to the external magenetic flux density. The d. c discharge plasma was in the rectangular waveguide in which two electrode was inserted, and also the glass diseharge tube inserted in the ractangular wavegside. The direction of microwave pro-pagation, the axis of the discharge tube and external magnetic flux were perpendicular to each other. It showed that the attenuation and absorption of micro wave power propagated in the plasma was increased as the magnetic flux density, the discharge current and the pressure of the gas were increased.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.699-706
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• 1991

The moderate power (500 W) Microwave Induced Plasma was generated with helium gas and was used for the direct analysis of aqueous samples. Usually, the helium plasma obtained with a modified Beenakker type cavity forms a cylindrical one. Though, by the careful controls of gas flows, a "toroidal" shape plasma could be made but its analytical performances were found to be worse. Using the glass frit nebuliser, the detection limits for metal ions obtained were around 10~100 ppb and that for chloride was about 50ppm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.897-903
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• 2009

We have designed the backward wave oscillator. A power-pulsed generator oscillated at 24 GHz has higher frequency than current one. It is very inportant to prevent microwave from going into the beam diode, since intence microwave will harmfully affect beam generation. Due to the axial mode operation, there exist a critial value of beam energy for the oscillation. By changing the condition at the SWS end, an enhanced performance of the K-band oversized BWO is observed in a low magnetic field region about 0.8T.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.229-239
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• 2018

The purpose of this study was to effectively produce the biosugar from cell wall of lipid extracted microalgae (LEA) by using microwave-assisted pretreatment without enzymatic hydrolysis process. Response surface methodology (RSM) was applied to optimization of microwave-assisted pretreatment conditions for the production of biosugar based on enzyme-free process from LEA. Microwave power (198~702 W), extraction time (39~241 sec), and sulfuric acid (0~1.0 mol) were used as independent variables for central composite design (CCD) in order to predict optimum pretreatment conditions. It was noted that the pretreatment variables that affect the production of glucose (C6) and xylose (C5) significantly have been identified as the microwave power and extraction time. Additionally, the increase in microwave power and time had led to an increase in biosugar production. The superimposed contour plot for maximizing dependent variables showed the maximum C6 (hexose) and C5 (pentose) yields of 92.7 and 74.5% were estimated by the predicted model under pretreatment condition of 700 w, 185.7 sec, and 0.48 mol, and the yields of C6 and C5 were confirmed as 94.2 and 71.8% by experimental validation, respectively. This study showed that microwave-assisted pretreatment under low temperature below $100^{\circ}C$ with short pretreatment time was verified to be an effective enzyme free pretreatment process for the production of biosugar from LEA compared to conventional pretreatment methods.

• ETRI Journal
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• v.35 no.3
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• pp.546-549
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• 2013

A Ka-band 6-W high power microwave monolithic integrated circuit amplifier for use in a very small aperture terminal system requiring high linearity is designed and fabricated using commercial 0.15-${\mu}m$ GaAs pHEMT technology. This three-stage amplifier, with a chip size of 22.1 $mm^2$ can achieve a saturated output power of 6 W with a 21% power-added efficiency and 15-dB small signal gain over a frequency range of 28.5 GHz to 30.5 GHz. To obtain high linearity, the amplifier employs a class-A bias and demonstrates an output third-order intercept point of greater than 43.5 dBm over the above-mentioned frequency range.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.38.4-39
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• 2018

We analyze the Planck 2015 cosmic microwave background temperature fluctuation data to find any anomaly in the angular power spectra measured for partial regions on the sky. For disks with radius of $20^{\circ}$, $45^{\circ}$ and $90^{\circ}$, which are densely overlapping on the sky, we estimate the power excess and its statistical significance relative to the LambdaCDM expectation for some chosen ranges of angular scales. We also investigate the dipolar asymmetry using the power excess maps obtained for some chosen angular scales, and confirm the previously announced consistent dipole directions. The average dipole amplitude and the inner products of dipoles have been measured from the power excess maps at different angular scales. We conclude that although dipole directions are consistent the measured amplitudes are not statistically significant compared to the LambdaCDM model prediction.

• Journal of information and communication convergence engineering
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• v.17 no.3
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• pp.221-226
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• 2019

In this work, a transmitter/receiver front-end module (T/R FEM) with an automatic Tx/Rx switching scheme for a 2.4 GHz microwave power transfer is developed for a retro-reflective beamforming scheme. Recently, research on wireless power transfer techniques has moved to wireless charging systems for mobile devices. Retro-reflective beamforming is a good candidate for tracking the spatial position of a mobile device to be charged. In Tx mode, the T/R FEM generates a minimum of 1 W. It also comprises an amplitude and phase monitoring port for transmitting RF power. In Rx mode, it passes an Rx pilot signal from a mobile device to a digital baseband subsystem to recognize the position of the mobile device. The insertion loss of the Rx signal path is 4.5 dB. The Tx and Rx modes are automatically switched by detecting the Tx input power. This T/R FEM is a design example of T/R FEMs for wireless charging systems based on a retro-reflective beamforming scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2227-2235
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• 2009

This paper describes the system configuration and measured performances of a wireless power transmission system which utilizes microwave. The technically final target of this system is to provide DC power to various mobile terminals within limited spaces such as buildings, conference rooms, and so on. The prototype system is built using in-house designed and fabricated circuits such as microwave oscillator, high power amplifier, microstrip patch antenna, low pass filter, and detector/rectifier. The fixed RF power of 29.3dBm at 2.4GHz is produced from the high power amplifier and transmitted through the transmitting antenna, while the received RF power at the receiving antenna is transformed into DC power through the detector/rectifier. The measured change of DC voltage according to the distance between transmitting and receiving antenna is described.

• Journal of the Korean Society of Safety
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• v.22 no.5
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• pp.27-32
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• 2007

We investigated the damage of the TTL ICs which manufactured five different technologies by artificial microwave. The artificial microwave was rated at a microwave output from 0 to 1000W, at a frequency of 2.45GHz. The microwave power was extracted into a standard rectangular waveguide(WR-340) and TTL ICs were located into the waveguide. TTL ICs were damaged two types. One is breakdown which means no physical damage is done to the system and after a reset the system is going back into function. The other is destruction which means a physical damage of the system so that the system will not recover without a hardware repair. TTL SN74S08N and SN74ALS08N devices get a breakdown and destruction occurred but TTL SN74LS08N, SN74AS08N and 74F08N devices get a destruction occurred. Also destructed TTL ICs were removed their surface and a chip conditions were analyzed by SEM. The SEM analysis of the damaged devices showed onchipwire and bondwire destruction like melting due to thermal effect. The tested results expect to be applied to the fundamental data which interprets the combination mechanism of the semiconductors from artificial microwave environment.