• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1576-1585
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• 1997

The microexplosive combustion of a slurry droplet was investigated experimentally. The microexplosion has been approximately considered to be caused by pressure build-up in the shell and to be promoted by heterogeneous nucleation of liquid carrier, which is due to the suppression of evaporation and subsequent superheating of liquid carrier. To closely investigate the pressure build-up and the heterogeneous nucleation, the experiments were conducted in an electric combustor, of which temperature was controllable (400 K-900 K). And the effects of two aligned droplets on the interactive combustion and microexplosion were found in a hot post region of a flat flame burner. Transient internal temperature distributions for slurry droplets were measured. And the shell formation and the microexplosion of suspended A1/JP-8 and Al/n-heptane slurry droplets were examined with various surfactant concentrations (0.5-5 wt%) and solid loadings (10-50 wt.%). The microexplosion time of binary array of droplets was found to be less than that of the isolated droplet due to radiative interaction between droplets.

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.302-307
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• 2019

The intrinsic oxygen-vacancy defects in ZnO have prevented the preparation of p-type ZnO with high carrier concentration. Therefore, in this work, the effect of the concentration of H₂O₂ (used as an oxygen source) on the oxygen-vacancy concentration in ZnO prepared by atomic layer deposition was investigated. The results indicated that the oxygen-vacancy concentration in the ZnO film decreased by the oxygen-rich growth conditions when using H₂O₂ as the oxygen precursor instead of a conventional oxygen source such as H₂O. The suppression of oxygen vacancies decreased the carrier concentration and increased the resistivity. Moreover, the growth orientation changed to the (002) plane, from the combined (100) and (002) planes, with the increase in H₂O₂ concentration. The passivation of oxygen-vacancy defects in ZnO can contribute to the preparation of p-type ZnO.

• Transactions on Electrical and Electronic Materials
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• v.13 no.4
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• pp.188-191
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• 2012

This paper introduces a new method regarding deuterium incorporation in the gate dielectric including deuterium implantation and post-annealing at the back-end-of-the process line. The control device and the deuterium furnace-annealed device were also prepared for comparison with the implanted device. It was observed that deuterium implantation at a light dose of $1{\times}10^{12}-1{\times}10^{14}/cm^2$ at 30 keV reduced hot-carrier injection (HCI) degradation and negative bias temperature instability (NBTI) within our device structure due to the reduction in oxide charge and interface trap. Deuterium implantation provides a possible solution to enhance the bulk and interface reliabilities of the gate oxide under the electrical stress.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.3-6
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• 2004

This paper. we investigate the OFDM-based wireless LAN systems operating in the 60 GHz frequency band as part of the fourth-generation (4G) systems. The 60 GHz band is of much interest since this is the band in which a massive amount of spectral space (5 GHz) has been allocated worldwide for dense wireless local communications. This paper gives an overview of 60 GHz indoor wireless channel characteristics and an effect on phase noise. The performance of OFDM system is severely degraded by the local oscillator phase noise, which causes both common phase error and inter-carrier interference. We provide the exact analysis of the phase noise effect on the OFDM system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.127-128
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• 2006

The proposed differential LC cross-coupled VCO is implemented in InGap/GaAs HBT process for an adaptive Global Positioning system(GPS) application. Two filtering capacitors are used at the base of output buffer amplifiers at the both sides of the core m order to improve phase noise characteristics. The VCO produced a phase noise of -133 dBc/Hz at 3MHz offset frequency from the carrier frequency of 1.489GHz and the second harmonic suppression is significantly suppresed up to -49dBc/Hz in simulation result. The three pairs of BC diodes are integrated m the tank circuit to increase the VCO Tunning range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.206-209
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• 2002

With the progress of semiconductor processing technology, avalanohe photodiodes (APDs) based on InP/InGaAs are used for high-speed optical receiver modules. Planar-type APDs give higher reliability than mesa-type APDs. However, Planar-type APDs are struggled with a problem of intensed electric field at the junction curvature, which causes edge breakdown phenomena at the junction periphery. In this paper, we focused on studying the effects of junction curvature for APDs performances by different etching processes followed by single diffusion to from p-n junction. The performance of each process is characterized by observing electric field profiles and carrier generation rates. From the results, it can be understood to predict the optimum structure, which can minimize edge breakdown and improve the manufacturability.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.918-921
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• 1999

The breakdown voltage in fully depleted SOI N-MOSFET’s have been studied over a wide range of film thicknesses, channel doping, and channel lengths. An asynmmetric Source/Drain SOI technology is proposed, which having the advantages of Normal LDD SOI(Silicon-On-Insulator) for breakdown voltage and gives a high drivability of LDD SOI without sacrificings hot carrier immunity The two-dimensional simulations have been used to investigate the breakdown behavior in these device. It is found that the breakdown voltage(BVds) is almost same with high current drivability as that in Normal LDD SOI device structure.

• Journal of IKEEE
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• v.19 no.1
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• pp.27-32
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• 2015

A flexible and tunable microwave photonic filter based on adjustable optical frequency comb source is demonstrated. We use a combination of a dual parallel Mach Zehnder modulator and an intensity modulator to generate fifteen comb lines with proper weights to implement a desired filter. The optical comb weights, corresponding to the tap coefficients of the filter, are flexibly changed by adjusting the operation parameters of the modulators. The achieved bandwidth and stopband attenuation of the tunable filter are 0.7 GHz and 20 dB, respectively. In addition, we overcome the undesired low frequency suppression appeared in a conventional scheme by applying a dual parallel Mach Zehnder modulator for single sideband suppressed carrier modulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.815-820
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• 1998

A new coding algorithm which has spectrum notches at the DC and Nyquist Frequency for maximizing the effect of the in-band pilot insertion in order to make the symbol timing or carrier recovery easy is proposed. It is shown that this algorithm uses one encoder and gives the similar spectrum characteristics to that of the existing OF00 code which uses two encoder. In this paper, the proposed new coding algorithm is explained andits spectrum characteristics is compared with the of OF00 code using computer simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1284-1291
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• 2014

For detection and parameter estimation, a multicarrier radar should discriminate a channel containing jamming signal and either leave it out or regenerate jammer suppressed target signal. To discriminate jamming channels, we use the angular spectrum of an eigenvector that embeds target echoes and jamming signals. We propose a criteria to discriminate the jammer channels and its basis through mathematical analysis. Moreover, we show some procedures to regenerate the jammer suppressed target echoes. Finally, the validity of the proposed method is demonstrated through simulation results showing improved performance in terms of direction of arrival(DOA) estimation.