• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1301-1307
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• 2004

Reduced pressure chemical vapor deposition(RPCYD) technology has been investigated for the growth of SiGe epitaxial films with two dimensional in-situ doped boron impurities. The two dimensional $\delta$-doped impurities can supply high mobility carriers into the channel of SiGe heterostructure MOSFETs(HMOS). Process parameters including substrate temperature, flow rate of dopant gas, and structure of epitaxial layers presented significant influence on the shape of two dimensional dopant distribution. Weak bonds of germanium hydrides could promote high incorporation efficiency of boron atoms on film surface. Meanwhile the negligible diffusion coefficient in SiGe prohibits the dispersion of boron atoms: that is, very sharp, well defined two-dimensional doping could be obtained within a few atomic layers. Peak concentration and full-width-at-half-maximum of boron profiles in SiGe could be achieved in the range of 10$^{18}$ -10$^{20}$ cm$^{-3}$ and below 5 nm, respectively. These experimental results suggest that the present method is particularly suitable for HMOS devices requiring a high-precision channel for superior performance in terms of operation speed and noise levels to the present conventional CMOS technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.45-45
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• 2008

In recent years, new materials and technology has been developed using single-walled carbon nanotubes (SWCNTs) as an alternative to indium tin oxide (ITO) to fulfil the requirements towards novel technological drive. These technologies offer products having a broad range of conductivity, excellent transparency, neutral color tone, good adhesion, abrasion resistance as well as mechanical robustness. In addition, SWCNTs can be solution processed to replace the sophisticated vacuum techniques at high temperatures. In the present work, transparent conducting films were fabricated from the purified SWCNTs. Dispersion of purified SWCNTs was accomplished in 1,2-dichlorobenzene without using surfactants or polymers following ultrasonic process. We achieved coating of nanotubes film on poly ether suiphone (PES) for an average sheet resistance ~110 ${\Omega}/{\Box}$ of optical transmittance 80% at 550 nm. Conventional spin coating method was followed to fabricate films from the purified and dispersed nanotubes solution. The results will be presented.

• Journal of Industrial Technology
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• v.7
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• pp.49-58
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• 1987

To investigate the effect of the Retrogression and Reaging (RRA) treatment on the strength and the stress corrosion cracking in AA 7039 the measurement of hardness, tensile properties and the time to failure in a constant rate method were measured. Transmission electron microscope was used to examine the microstructural changes within graln and grain boundary. The results show that the RRA treatment of the T6 condition results in a significant increase in the time to failure without sacrifying the original T6 strength. It is believed that high density and even distribution of precipitates in RRA condition were observed within grain so that the RRA condition could have similar strength to the T6 condition. The presence of fine dispersion of semicohernt ${\eta}^{\prime}$ transition phase is also believed to contribute to that effect. Examination of the grain boundary microstructure shows that the RRA treatments increases significantly the average size of the grain boundary preciptates. It is suggested that the benificial effect of the RRA treatment on the susceptibility to SCC be due to the increase in the size of grain boundary precipitates obtained during the retrogression treatment.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.114-121
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• 1996

Thin film Ba$^{0.7}Sr^{0.3}TiO^{3}$ (BST) capacitors were fabricated on SiO$_{2}$/Si substrates by RF magnetron sputtering method and characterized at microwave frequencies ranging from 40 MHz to 1GHz to examine the dielectric dispersion of the capacitors. The BST thin films were electrode material of BST thin films capacitor which is known as one of the best electrode materials for BST films. 50$\AA$-thick titanium (Ti) layers were introduced to increase adhesion between bottom Pt and SiO$_{2}$. The leakage current density of the capacitors was about 1.7${\times}10^{7}A/cm^{2}$ at 1.5V and the dielectric constant was about 140 at 1MHz. Microwave measurement patterns having a coplanar waveguide type were fabricated and their S parameters were measured using network analyzer. After de-embedding parasitic components in microwave measurement patterns nearly frequency-invariant dielectric constant of about 120 was extracted in the measurement range of 40 MHz to 1 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.95-101
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• 2008

This paper presents a novel bandpass filter design method for suppressing spurious response in the GSM band and effectively reducing the overall size with the unbalanced-conditioned metamaterials. Compared to the conventional bandpass filters based on half-or quarter-wave resonators, the CRLH(composite right/left-handed) bandpass filter works excellently in harmonic-suppression by 40$\sim$50 dB and 80 %-miniaturization using the zero-order resonators bridged by Inductive-coupling Inverters suggested first time. The proposed technique, with the equivalent circuit and dispersion diagram, is validated by performance predictions and experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1039-1044
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• 2014

Many research works have been conducted to improve a lubrication performance on diesel engines working in severe conditions. In this study the lubricant containing diamond nano-powder is applied on a diesel engine, and the engine performance is analyzed. The concentration of nano-diamond lubricant fabricated by the matrix synthesis dispersion method is varied. The test results with the nano lubricants are compared with the base oil. The result shows the improvement of efficiency with friction reduction and exhaust emissions reduction of CO, smoke and so on.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.56-59
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• 2004

An experimental study has performed to identify the mixing characteristics of basket mill by using PIV and LIF techniques. The velocity fields were measured at three sectors for each two types of basket mill model and various impeller speed. To verify the results of velocity field measurement and the concentration field, LIF measurement also was performed for three cases. There was an inactive region and a descending flow to the bottom of basket mill at the original model. But when the impeller type and the guide shape were changed, internal flow structure was improved suitably for mixing and dispersion. The improvement result in increment of inflow flow rate at the basket entrance about $10\%$.

• Toxicological Research
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• v.26 no.4
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• pp.253-259
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• 2010

We are consistently being exposed to nanomaterials in direct and/or indirect route as they are used in almost all the sectors in our life. Nations across the worlds are now trying to put global regulation policy on nanomaterials. Sometimes, they are reported to be more toxic than the corresponding ion and micromaterials. Therefore, safety research of nanoparticles has huge implications on a national economics. In this study, we evaluated and analyzed the research trend of ecotoxicity of nanoparticles in soil environment. Test species include terrestrial plants, earthworms, and soil nematode. Soil enzyme activities were also discussed. We found that the results of nanotoxicity studies were affected by many factors such as physicochemical properties, size, dispersion method and test medium of nanoparticle, which should be considered when conducting toxicity researches. In particular, more researches on the effect of physicochemical properties and fate of nanoparticles on toxicity effect should be conducted consistently.

• Korea-Australia Rheology Journal
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• v.16 no.4
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• pp.175-182
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• 2004

Colloidal coating solution was prepared to enhance the hydrophilic property of the film surface. Water and ethanol were used as the dispersion media and (glycidoxypropyl) trimethoxysilane (GPS) as a binder in the colloidal silica coatings. Ethylene diamine was added to the colloidal silica solution as the curing agent. The colloidal silica solution was regarded as a hard-sphere suspension model with low volume fraction of the silica particles. Rheological properties of the silica suspensions modified with GPS have been investigated as a function of pH and concentration. The acidic solution showed high viscosity change by fast hydrolysis reaction and adsorption of the organic binders on the surface of silica particles. However, the hydrolysis was slow at the basic condition and the binders combined with themselves by condensation. The viscosity change was smallest at pH 7. The viscosity increased with the curing time after adding ethylenediamine, and the increase of viscosity at low pH was higher than that at high pH. The hydrophilic properties of the coating film were investigated by the contact angle of water and film surface. The smallest contact angle was shown under the strong acidic condition of pH 2.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.65-70
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• 2020

While the demand for robots in the manufacturing industry has dramatically increased, the industrial robots' functionality is mainly determined by the effector attached to the end of their arms. They need a flexible gripping system that can act as a human hand and easily grasp a variety of objects, which requires resilient sensors. This study clarifies the electrical output characteristics of elastic tactile sensors according to contact terminals because the output characteristics of the tactile sensors vary greatly, depending on the contact material and the method of contact with the conductive wire. Our research considers the Three Roll Mill and Paste Mixer as the dispersion medium, and a nickel- and gold-plated brass electrode as the contact terminal.