• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.63-66
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• 2003

In this paper, the electrical characteristics of single oxide layer due to high temperature diffusion process, wafer resistivity and thickness of poly backseat was researched. The oxide quality was examined through capacitance-voltage characteristics, and besides, it will be describe the capacitance-voltage characteristics of the single oxide layer by semiconductor device simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.387-390
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• 1999

Electron swarm parameterdthe drift velocity and longitudinal diffusion coefficienthn $SiH_4-Ar$ mixtures containing 0.5% and 5% monosilane were measured using over the range of E/N from 0.01 to 300 Td at room temperature. Electron swarm parameters in argon were drastically changed by adding a small amount of monosilane. The electron drift velocity in both mixtures showed unusual behaviour against E/N. It had negative slope in the medium range of E/N, yet the slope was not smooth but contained a small hump. The longitudinal diffusion coefficient also showed a corresponding feature in its dependence on E/N. A two-tern approximation of the Boltzmann equation analysis and Monte Carlo simulation have been used to study electron transport coefficients.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.217-220
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• 2004

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we did the durability test such as chloride ion diffusion, chemical attack. repeated freezing and thawing, carbonation. In the chloride ion diffusion test, according to the increase of substitute of metakaolin & silica-fume for binder, the diffusion coefficient is more reduced. And in the chemical attack test, according to the increase of substitute, the resistance is more excellent. In the other durability test, the concrete using metakaolin is also compared with those of the portland cement concrete and silica fume concrete. According to these tests, we recognized that metakaolin is able to be used as a substitute for silica-fume.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.5
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• pp.400-406
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• 1998

We investigated the preparation and guided-mode properties of $Ti:LiNbO_3$ waveguides which were fabricated by Ti in-diffusion. The diffusion method to reduce the Li out-diffusion was proposed. The optical guided-mode and propagation loss based on butt-coupling pigtailed with PMF-input were measured. How to improve the polishing grade of waveguide endfaces is newly proposed in this paper. To show the mode propagations, the BPM simulations of channel waveguide are described.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.73-76
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• 1997

A low loss x-cut LiNbO$_3$ optical waveguide was fabricated by Ti in-diffusion and the guided-mode properties and total insertion loss of pigtailing with polarization maintaining fiber(PMF) were investigated and measured at optical wavelength 15507. For formaing the waveguide, the parameters of diffusion Ti thickness, waveguide line-width, length, diffusion temperature, time and atmosphere were set 1400$\AA$, 8${\mu}{\textrm}{m}$, 3.3cm, 105$0^{\circ}C$, 8 hours and wet bubbled oxygen, respectively. and then After the polishing and pigtailing, it showed that total insertion loss was -4.1dB for TM mode, -5.5dB for TE mode, and mode size, that is, horizontal/vertical sizes were 13.87/18${\mu}{\textrm}{m}$ for TM mode, 9.61${\mu}{\textrm}{m}$/6.5${\mu}{\textrm}{m}$ for TE mode.

• Journal of Surface Science and Engineering
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• v.32 no.3
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• pp.433-439
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• 1999

In this study, the diffusion barrier properties of $1000\AA$ thick molybdenum compounds (Mox=1-5 Si) were investigated using sheet resistance measurements, X-ray diffractometry (XRD), and Rutherford back scattering spectrometry (RBS). Each barrier material was deposited by the de and rf magnetron co-sputtering of Mo and Si, respectively, and annealed at $500-700^{\circ}C$ for 30 min in vacuum. Each barrier material was failed at low temperatures due to Cu diffusion through grain boundaries and defects of barrier thin films or through the reaction of Cu with Si within Mo-barrier thin films. It was found that Mo rich thin films were less effective than Si rich films to Cu penetration activating Cu reaction with the substrate at a temperature higher than $500^{\circ}C$.

• Computers and Concrete
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• v.3 no.2_3
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• pp.103-122
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• 2006

Drying shrinkage of concrete occurs due to the loss of moisture and thus, it is controlled by moisture diffusion process. On the other hand, the shrinkage causes cracking of concrete and affects its moisture diffusion properties. Therefore, moisture diffusion and drying shrinkage are two coupled processes and their interactive effect is important for the durability of concrete structures. In this paper, the two material parameters in the moisture diffusion equation, i.e., the moisture capacity and humidity diffusivity, are modified by two different methods to include the effect of drying shrinkage on the moisture diffusion. The effect of drying shrinkage on the humidity diffusivity is introduced by the scalar damage parameter. The effect of drying shrinkage on the moisture capacity is evaluated by an analytical model based on non-equilibrium thermodynamics and minimum potential energy principle for a two-phase composite. The mechanical part of drying shrinkage is modeled as an elastoplastic damage problem. The coupled problem of moisture diffusion and drying shrinkage is solved using a finite element method. The present model can predict that the drying shrinkage accelerates the moisture diffusion in concrete, and in turn, the accelerated drying process increases the shrinkage strain. The coupling effects are demonstrated by a numerical example.

• Transactions of Materials Processing
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• v.5 no.1
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• pp.37-46
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• 1996

Superplastic forming/diffusion bonding (SPF/DB) processes were analyzed using a rigid visco-plastic finite element method. The optimum pressure-time relationship for a target strain rate and thickness distributions were predicted by two-node line elements based on the membrane approximation for plane strain. Material behavior during SPF/DB of the integral structures having complicated shapes was investigated. The tying condition is employed for the analysis of inter-sheet contact problems. A movement of rib structure is successfully predicted during the forming.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.785-790
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• 2002

Distributions of residual stress in diffusion bonding of dissimilar materials intermetallics TiAl to steel 40Cr were simulated by FEM calculation. Results showed that destructive residual stresses presented in the minute area adjacent to bond-line of the base material with smaller coefficient of thermal expansion. Reducing bonding temperature and diminishing bonding time are in favor of the mollification of interface tresses.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.159-160
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• 2020

This study examined the potentials for developing a biological coating material with high chloride resistance. The bacteria strains isolated were Halomonas alkaliphile, Halomonas venusta, and Sulfidobacter mediterraneus. Test results revealed that the developed approach is very promising in reducing the chloride ion diffusion coefficient of concrete.