• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.82-86
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• 2013

A poled lead zirconate titanate (PZT) cube specimen is subjected to impulse-type compressive stress with increasing magnitude in parallel to the poling direction at four room and high temperatures. During the ferroelastic domain switching induced by the compressive stress, electric displacement in the poling direction and longitudinal and transverse strains are measured. Using the measured responses, linear material properties, namely, the piezoelectric and elastic compliance coefficients, are evaluated by a graphical method, and the effects of stress and temperature are analyzed. Finally, the dependency of the evaluated linear material properties on relative remnant polarization is analyzed and discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.124-127
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• 2002

A CMOS voltage regulation circuit for use at low-voltage is proposed. Circuits for a positive and for a negative current regulation are presented and are designed with commercial CMOS technology. The voltage regulation that is stable over ambient temperature variations is an important component of most data acquisition systems. These results are verified by the H-SPICE simulation $0.8{\mu}m$ parameter. As the result, the temperature dependency of output voltage is $0.57mV/^{\circ}C$ and the power dissipation is 1.8 mV on 5V supply voltage.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.44-46
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• 2001

Increase of gate leakage current causes decrease of gain and increase of noise. In this paper, gate leakage current of GaAs MESEFTs' has been traced with different temperatures from $27^{\circ}C\;to\;350^{\circ}C$ to obtain the zero voltage saturation current $J_s$ which is critical to the temperature dependency of total current. From the results, thermal leakage current coefficient has been proposed to compensate for the total current due to the thermionic emission, tunneling, generation and/or hole injection.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.299-304
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• 2001

An approach is developed for parametric investigation of the influence of the surface roughness on thermohydrodynamic analysis with film conditions which systemically occur in journal bearings. A parametric investigation is performed for predicting the bearing behaviors such as pressure and temperature distributions in lubricating films between the stationary and moving surfaces determined by absorbed layers and interfaces on the statistical method for rough surface with Gaussian distribution. The layers expressing the effects of surface roughness are expressed as functions of the standard deviations (${\sigma}$) of each surface and surface orientation (j) to explain the flow patterns between both rough surfaces. The coupled effect of surface roughness and shear zone dependency on hydrodynamic pressure and temperature has been found by solving the present model in non-contact mode and contact mode, respectively.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1312-1316
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• 2004

The Stirling refrigerators have been widely used for the cooling of the infrared detector and HTS to the cryogenic temperature. The Stirling refrigerator with the rotary compressor are applicable to the cooling device for the compact mobile thermal imaging system, because the refrigerators have the compact structure and light weight. The typical performance factors of the Stirling refrigerator are the cool-down time, cooling capacity at the desired temperature and the input power. And the above performance factors are depends on the thermal insulation characteristics of the Dewar. In this study, the steady thermal load of the Dewar and the performance of the Stirling refrigerator were measured. The results show the dependency of the input power and the charging pressure on the performance of the refrigerator.

• Transactions on Electrical and Electronic Materials
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• v.5 no.3
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• pp.122-125
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• 2004

ITO films were deposited on polyethylene terephthalate substrate by a dc reactive magnetron sputtering using rf bias without substrate heater and post-deposition thermal treatment. The dependency of rf substrate bias on plasma sputter processing was investigated to control energetic particles and improve ITO film properties. The substrate was applied negative rf bias voltage from 0 to -80 V. The composition of indium, tin, and oxygen atoms is strongly depended on the rf substrate bias. Oxygen deficiency is the highest at rf bias of -20 V. The electrical and optical properties of ITO films also are dominated obviously by negative rf bias.

• Journal of the Korean Vacuum Society
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• v.5 no.2
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• pp.127-132
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• 1996

We measured photoreflectance spectrum characteristics of InGaAs grown by MBE method on semi-insulating GaAs. The PR signal splitting of substate and epilayer was observed. The band gap energy was about 1.40 eV. It make to 8 meV difference when it is fitted by Pan's equation. The reason is stress on the interface, which is due to lattice mismatch between epilayer and substate . We became to know that reason influence crystalline on growing sample. In InGaAs epilayer, temperature dependency is low. The efficiency of photo absorption is high and activate over 200K. In this case when it is annealed at $400^{\circ}C$ below growing temperature, PR signal splitting is remarkable and crystalline is inhanced.

• Journal of the Korean Ceramic Society
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• v.28 no.7
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• pp.517-524
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• 1991

The CVD process of BPSG (BoroPhosphoSilicate Glass) and its thin film properties were studied. B2H6, PH3, SiH4 and O2 gases were reacted in a AP (Atmospheric Pressure) CVD system in the temperature range of 300℃ and 460℃. The interaction of B2H6 and PH3 was studied from the deposition rate and dopant incorporation change point of view. The dependency of BPSG step coverage on the temperature was changed with different O2/(B2H6+PH3+SiH4) ratio. Finally, the boundary which distinguishes the stable BPSG's from the ones that react with Di (Deionized) water or cleaning chemicals such as H2SO4, HCl, H2O2, NH4OH etc could be defined.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.930-936
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• 1999

For LiMn2O4 based spinel structures the stoichiometric reaction conditions need be considered carefully because the electrical properties depend on the structural stability. In order to obtain the homogeneous compound the Pechini process was chosen which could obtain a stoichiometry phase even low temperature and dependency of the synthetic condition on structural stability and electrochemical performance was investigated. X-ray diffraction studies showed that the compounds doped with transition metal have smaller lattice constants than those un doped. The dc conductivity was evaluated by a four probe method in the low and high temperature region respectively. The variations of basal spacings for the cathode were detected to be dependent on the extent of current flows (under dc)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1239-1243
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• 2004

A novel voltage-current reference circuit for stable voltage-current applications is Proposed. Circuits for a positive and for a negative voltage-current reference are presented and are designed with commercial CMOS technology. The voltage-current reference that is stable over ambient temperature variations is an important component of most data acquisition systems. These results are verified by the HSPICE simulation $0.8{\mu}m$ parameter. As the result, the temperature dependency of output voltage and output current each is $0.57mV/^{\circ}C$, $0.11{\mu}A/^{\circ}C$ and the power dissipation is 1.8 mV on 5V supply voltage.