• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.582-585
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• 2004

Pb0.5Sr0.5TiO3 (PST) thin films were fabricated by the alkoxide-based sol-gel process using spin-coating method on Pt/Ti/SiO2/Si substrate. The PST films annealed from 500C to 650C for 1h show a perovskite phase and dense microstructure with a smooth surface. The grain size and dielectric constant of PST films increases with the increase in annealing temperature, which reduces the SiO2 equivalent thickness of the PST film. The crystallinity or internal strain in the PST thin films analyzed from the diffraction-peak widths correlate well with the decrease in the dielectric losses. The dielectric constants and dielectric loss (%) of the PST films annealed at 650c (teq : 0.89 nm) were 549 and 0.21%, respectively.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1231-1236
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• 1996

The electrode resistance of semiconducting PTC BaTiO3 ceramic material was studied in some detail. Comme-rical In-Ag paste In-Ga alloy and electroless plated Ni as well as evaporated Al were chosen as electrode. The contact resistance of electroded samples were measured by both dc resistivity and ac impedance analysis. The aging effect on contact resistance under cyclic loading from -1$0^{\circ}C$ to 85$^{\circ}C$ was also monitored for the prolonged period of time. In case of Al electroded samples the heat treatment and protective coating had effects on the stability against contact resistance degradation. It was also found that the samples with commercial In-Ag paste and electroless plated Ni electrode had good properties of contact resistance against aging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.19-19
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• 2010

We suggest CNT-based gas sensors for breath alcohol measurement. The sensors were composed of single-walled carbon nanotubes (SWNTs) thin film on glass substrate with simple process, and the SWNTs thin film as sensing layer was formed by multiple spray-coating with SWNT composites which was well-dispersed, highly controlled and differently functionalized by various binders (TEOS, MTMS, and VTMS) added in ethanol solvent. In this work, three different SWNTs thin films were made to compare their electrical response properties for alcohol vapor. From fabricated sensors, conductance responses were measured and discussed. In the result, our alcohol gas sensors showed an effective selectivity even at room temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.297-302
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• 2009

We have successfully fabricated the alumina thick films using inkjet printing processes without a high temperature sintering process. Alumina suspension as dielectric ink was formulated by combining nano-sized alumina powders with an anionic polymer dispersant in formamide/water as co-solvent. The thickness of the printed alumina thick film was measured at around 5 um by field emission scanning electron microscope. The calculated packing density of 68.5 % from the printed alumina thick film was much higher than the same films fabricated by conventional casting or dip coating processes. Q factor of the dielectrics thick film infiltrated with cyanate ester resin was evaluated by impedance analyzer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.331-331
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• 2008

Transparent conductive oxide (TCO) are necessary as front electrode or anti-reflecting coating for increasing efficiency of LED and Photodiode. In this paper, aluminum-doped Zinc oxide films(AZO) were prepared by RF magnetron sputtering on Si substrate at room temperature with application of substrate bias from -60 to 60 V. Then annealed at temperature of 200, 300 and $400^{\circ}C$ for 1hr in $H_2$ ambient. Structural and electrical property of AZO thin films were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.382-383
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• 2008

In this paper we presented experimental results of a gas sensor utilizing multi-walled carbon nanotube (MWNT)composites for the alcohol detection which is useful to checking drinking and driving, for example. The MWNT-composites were deposited using spray method on PES substrates suitable for use in low-cost and flexible sensors. We observed the variation of conductance from the sensors exposed to alcohol vapors evaporated at 37C equal to the human body temperature to match real condition. As the result, the conductance was decreased with the increase of ethanol vol% diluted in water. The sensors showed good sensitivity and linearity.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.204-209
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• 1995

The influence of the interfacial properties on the bond capacity of reinforcing bars to concrete is studied in this paper. In this study, the deterioration of the interfacial bond capacity when top-cast bars or epoxy-coated bars are used is examined. The effect of such variables on bond capacity in reinforced concrete is studied by experiment which use beam-end specimens. The main objective of this study is that comparing the test results and the requirements in ACI 318-89 code. the verification of the factor in ACI code is also presented in this paper. The results of the test show that "top bar effect" is considerably affected by the slump of fresh concrete, so the influence of slump shoud be taken into account for top bar effect factor in code. Test results also shows that the bond-slip curve of the epoxy-caoted bars is similiar to that of the uncoated and bond strength is reduced about 15% and that coating thickness seems to influence the bond strength deterioration.rioration.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.815-820
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• 2001

According as industry is complex, architecture is changing into the complex and diverse style and also customer's demands are becoming diversified. Among these, a door field is very important as much as saying nothing of more explanation. In this paper, in order to develop large floor hinge, mechanical properties of component parts are measured by vickers hardness tester, microstructure analysis and at the same time, these are designed by the FEM analysis.

• Structural Engineering and Mechanics
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• v.57 no.4
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• pp.703-716
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• 2016

In this paper, we have investigated shear horizontal wave propagation in a layered structure, consisting of granular macromorphic rock (Dionysos Marble) substrate underlying a viscoelastic layer of finite thickness. SH waves characteristics are affected by the material properties of both substrate and the coating. The effects of microstructural parameter "characteristic length" of the substrate, along with heterogeneity, internal friction and thickness of viscoelastic layer are studied on the dispersion curves. Dispersion equation for SH wave is derived. Real and damping phase velocities of SH waves are studied against dimensionless wave number, for different combinations of various parameters involved in the problem.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.11
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• pp.1507-1515
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• 2004

Washable wool was developed using environmental-friendly spray UV-cure technique. Photocrosslinkable polymer, dextran-methacrylate, was synthesized starting from natural biopolymer, dextran. The aqueous solution of dextran-methacrylate was applied to wool fabric with various concentrations to find out the optimum condition in minimizing felting shrinkage. The wool fabric subsequently cured by 365 nm UV, The effects of UV-cure time and photoinitiator concentration on felting behavior of wool were examined. As the concentration of dextran-methacrylate increased, the felting shrinkage decreased gradually. At concentration 0.5g/ml, the felting shrinkage of wool was negligible. Other properties such as air permeability, moisture content, wrinkle recovery, thickness and wettability were also evaluated. The surface coating of dextran polymer onto wool fiber was identified by SEM.