• Computers and Concrete
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• v.10 no.1
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• pp.79-93
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• 2012

This paper estimates theoretically the diffusion-reaction behaviour of sulfate ion in concrete caused by environmental sulfate attack. Based on Fick's second law and chemical reaction kinetics, a nonlinear and nonsteady diffusion-reaction equation of sulfate ion in concrete, in which the variable diffusion coefficient and the chemical reactions depleting sulfate ion concentration in concrete are considered, is proposed. The finite difference method is utilized to solve the diffusion-reaction equation of sulfate ion in concrete, and then it is used to simulate the diffusion-reaction process and the concentration distribution of sulfate ion in concrete. Afterwards, the experiments for measuring the sulfate ion concentration in concrete are carried out by using EDTA method to verify the proposal model, and results show that the proposed model is basically in agreement with the experimental results. Finally, Numerical example has been completed to investigate the diffusion-reaction behavior of sulfate ion in the concrete plate specimen immersed into sulfate solution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.3
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• pp.139-143
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• 2017

N-type crystalline silicon solar cells have high metal impurity tolerance and higher minority carrier lifetime that increases conversion efficiency. However, junction quality between the boron diffused layer and the n-type substrate is more important for increased efficiency. In this paper, the current status and prospects for boron diffused layers in N-type crystalline silicon solar cell applications are described. Boron diffused layer formation methods (thermal diffusion and co-diffusion using $a-SiO_X:B$), boron rich layer (BRL) and boron silicate glass (BSG) reactions, and analysis of the effects to improve junction characteristics are discussed. In-situ oxidation is performed to remove the boron rich layer. The oxidation process after diffusion shows a lower B-O peak than before the Oxidation process was changed into $SiO_2$ phase by FTIR and BRL. The $a-SiO_X:B$ layer is deposited by PECVD using $SiH_4$, $B_2H_6$, $H_2$, $CO_2$ gases in N-type wafer and annealed by thermal tube furnace for performing the P+ layer. MCLT (minority carrier lifetime) is improved by increasing $SiH_4$ and $B_2H_6$. When $a-SiO_X:B$ is removed, the Si-O peak decreases and the B-H peak declines a little, but MCLT is improved by hydrogen passivated inactive boron atoms. In this paper, we focused on the boron emitter for N-type crystalline solar cells.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.3
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• pp.51-70
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• 2013

This paper develops a model to predict the adoption and level of usage of network technology in a two-level supply chain with buyer-supplier relationships. A firm's adoption of a new technology depends not only on its own beliefs of the new technology's costs and benefits, but also on the adoption decisions of other firms in the supply chain. A model first analyzes an individual supplier's decision about a new technology adoption considering with multiple suppliers and buyers. Individual suppliers' decisions are aggregated with a population model to project how new technology diffuses across the supply chain and examine the pattern of diffusion process. This study found that as more firms adopt in initial periods, the total amount of information to the potential adopters in the population increases, and then the number of firms persuaded by the information increases as the process moves up the distribution of adoption process. We consider three factors influencing the diffusion speed of the new technology in a supply chain network : mean benefits, cost sharing, and information provision. This study examines how such factors affect the reduction of threshold levels, which implies that reductions in threshold levels have an aggregate effect by accelerating the rate of adoption. In particular, we explore relationship factors available in practice in a buyer-supplier relationship and numerically examines how these relationship factors contribute to increase the diffusion speed of the technology in a two-level supply chain.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.41.2-41.2
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• 2011

Recently, scaling down of ULSI (Ultra Large Scale Integration) circuit of CMOS (Complementary Metal Oxide Semiconductor) based electronic devices become much faster speed and smaller size than ever before. However, very narrow interconnect line width causes some drawbacks. For example, deposition of conformal and thin barrier is not easy moreover metallization process needs deposition of diffusion barrier and glue layer. Therefore, there is not enough space for copper filling process. In order to overcome these negative effects, simple process of copper metallization is required. In this research, Cu-V thin alloy film was formed by using RF magnetron sputter deposition system. Cu-V alloy film was deposited on the plane $SiO_2$/Si bi-layer substrate with smooth and uniform surface. Cu-V film thickness was about 50 nm. Cu-V layer was deposited at RT, 100, 150, 200, and $250^{\circ}C$. XRD, AFM, Hall measurement system, and XPS were used to analyze Cu-V thin film. For the barrier formation, Cu-V film was annealed at 200, 300, 400, 500, and $600^{\circ}C$ (1 hour). As a result, V-based thin interlayer between Cu-V film and $SiO_2$ dielectric layer was formed by itself with annealing. Thin interlayer was confirmed by TEM (Transmission Electron Microscope) analysis. Barrier thermal stability was tested with I-V (for measuring leakage current) and XRD analysis after 300, 400, 500, 600, and $700^{\circ}C$ (12 hour) annealing. With this research, over $500^{\circ}C$ annealed barrier has large leakage current. However V-based diffusion barrier annealed at $400^{\circ}C$ has good thermal stability. Thus, thermal stability of vanadium-based thin interlayer as diffusion barrier is good for copper interconnection.

• ETRI Journal
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• v.26 no.4
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• pp.371-374
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• 2004

We propose and demonstrate a fabrication method of chirped fiber gratings by a thermal diffusion process. The method could suggest a direction for a simple and cost-effective implementation of chirped fiber grating-based devices.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.377-380
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• 2003

A new color image segmentation scheme is presented in this paper. The proposed algorithm consists of image simplification, region labeling and color clustering. The vector-valued diffusion process is performed in the perceptually uniform LUV color space. We present a discrete 3-D diffusion model for easy implementation. The statistical characteristics of each labeled region are employed to estimate the number of total clusters and agglomerative hierarchical clustering is performed with the estimated number of clusters. Since the proposed clustering algorithm counts each region as a unit, it does not generate oversegmentation along region boundaries.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.255-256
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• 2003

Simulations of atmospheric diffusion process under stable and unstable conditions were carried out using both numerical and experimental methods. Results from the previous study show that numerical simulation using 3-dimensional incompressible Navier-Stokes equation and density deviation are in good agreement with typical plume pattern. In this study, we use experimental data of temperature and wind profile obtained from a thermally stratified wind tunnel as initial conditions for numerical simulation and compare the results.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.18 no.1
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• pp.43-50
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• 2014

In this paper we discussed Euler-Maruyama method for stochastic differential equations with jump diffusion. We give a convergence result for Euler-Maruyama where the coefficients of the stochastic differential equation are locally Lipschitz and the pth moments of the exact and numerical solution are bounded for some p > 2.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.196-200
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• 1998

Effect of diffusion induced recrystallization(DIR) on mechanical properties of hot-pressed TiC was in-vestigated. The TiC specimen was electroplated with Cr and then heat-treated at 1550. Through the DIR process a new set of (Ti, Cr) C mixed carbide grains with uniform and small size was formed at the surface. As a consequence the scattering in fracture strength decreased and the toughness increased.

• Journal of the Korean Ceramic Society
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• v.32 no.12
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• pp.1349-1356
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• 1995

The change of permeation mechanism from Knudsen diffusion to micropore diffusion was observed after CVD modification of an alumina-sol coated alumina support which was prepared by slip coating process. Permselectivities of He/N2, H2/N2, and CO2/N2 were 5.67, 5.02, and 1.44, respectively. These values were higher than those under Knudsen diffusion controlled region.