• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.248-253
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• 1987

Boron diffusion into silicon through poly\ulcorneri-SiO2 was carried out for the diffusion with low concentration using CVD-BN. The result of direct boron diffusion from BN into silicon and that of boron diffusion through SiO2 from BN into silicon was compared with the result of boron diffusion through poly-Si-SiO2 from BN into silicon. In the case of boron diffusion through poly Si-SiO2, the low concentration diffusion was obtained, that is the boron surface concentration in silicon Cs=10**16 Cm**-3, and the glassy compounds were not seen.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.265-274
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• 2007

A study has been conducted to clarify NO emission behavior through preferential diffusion effects of $H_2$ and H in methane-hydrogen diffusion flames. A comparison is made by employing three species diffusion models. Special concerns are focused on what is the deterministic role of the preferential diffusion effects in flame structure and NO emission. The behavior of maximum flame temperatures with three species diffusion models is not explained by scalar dissipation rate but the nature of chemical kinetics. The preferential diffusion of H into reaction zone suppresses the populations of the chain carrier radicals and then flame temperature while that of $H_2$ produces the increase of flame temperature. These preferential diffusion effects of $H_2$ and H are also discussed about NO emissions through the three species diffusion models.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1019-1030
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• 2017

Diffusion is a crucial mechanism that regulates the migration of radioactive nuclides. In this study, an innovative numerical method was developed to simultaneously calculate the diffusion coefficient of both parent and, afterward, series daughter nuclides in a sequentially reactive through-diffusion model. Two constructed scenarios, a serial reaction (RN_1 ${\rightarrow}$ RN_2 ${\rightarrow}$ RN_3) and a parallel reaction (RN_1 ${\rightarrow}$ RN_2A + RN_2B), were proposed and calculated for verification. First, the accuracy of the proposed three-member reaction equations was validated using several default numerical experiments. Second, by applying the validated numerical experimental concentration variation data, the as-determined diffusion coefficient of the product nuclide was observed to be identical to the default data. The results demonstrate the validity of the proposed method. The significance of the proposed numerical method will be particularly powerful in determining the diffusion coefficients of systems with extremely thin specimens, long periods of diffusion time, and parent nuclides with fast decay constants.

• Textile Coloration and Finishing
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• v.16 no.1
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• pp.48-52
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• 2004

Diffusion/penetration rates of finishing agents are not a major criterion in the design of low molecular weight finishing agents. However, in the case of polymeric finishing agents, high molecular weights result in large hydrodynamic volumes and diffusion/penetration of the finishing agent into the substrate may become a critical factor in the design of textile finishing agents. Thus the effect of the molecular weight of a model compound, polyethylene glycol, on its diffusion through a cellulose membrane or cotton fabric is studied. Diffusion experiments of polyethylene glycol of molecular weight 400, 1000, 2000, 4600, 8000, and 10000 through cellulose membrane or fabric was carried out in a glass U-tube diffusion apparatus and the half penetration times and the penetration coefficients were determined. Both the half penetration times and the penetration coefficients exhibited a significant change between molecular weight 2000 and 2500 as the molecular weight of polyethylene glycol increased, suggesting that there is a critical molecular weight above which diffusion/penetration becomes difficult. Based on this study on a model compound, it is suggested that polymeric textile finishing agents can be expected to exhibit similar behavior.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.737-742
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• 2002

The chief factors for the penetration and diffusion of chloride ions in concrete are water-cement ratio(w/c), aging, thickness of cover concrete, chloride ions concentration of given environment, wet and dry conditions and etc. In this study, effect of w/c and aging on the characteristics of chloride ions diffusion in concrete were researched when environmental factors for the penetration and diffusion of chloride ions were constant. For this purpose, the voltages passing through the diffusion cell were measured by using accelerated test method using potential difference, and then diffusion coefficients of chloride ions by using Andrade's method were estimated for 44%, 49.5% and 55% of w/c, respectively. As a result, correlation among diffusion coefficients of chloride ions, w/c and aging were concluded through multiple regression model.

• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.1-10
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• 2009

This article reviewed transport behaviours of electroactive species in ionic compounds, focusing on chemical diffusion of Li through the transition metal oxide in a current flowing condition. For this purpose, a distinction has been first briefly made between migration and diffusion with respect to current, driving force and charge of electroactive species considered. Then, the equations for chemical diffusion are derived theoretically in open-circuit and current flowing conditions. Finally, the experimental methods such as ac impedance spectroscopy and current (potential) transient techniques are described in details for characterising chemical diffusion. In addition, the role of the thermodynamic enhancement factor in chemical diffusion is discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.715-720
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• 2003

The chief factors for the penetration and diffusion of chloride ions in concrete are water-cement ratio(W/C), aging, curing conditions, chloride ions concentration of given environment., wet and dry conditions and etc. In this study, of these factors effect of curing conditions such as standard and outdoor curing on the characteristics of chloride ions diffusion in concrete were researched when environmental factors for the penetration and diffusion of chloride ions were constant. For this purpose, the voltages passing through the diffusion cell were measured by using accelerated test method using potential difference, and then diffusion coefficients of chloride ions by using Andrade's method were estimated for 44%, 49.5% and 60% of w/c, respectively. As a result., according to curing conditions correlation among diffusion coefficients of chloride ions, W/C and aging were concluded through multiple regression model.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.409-412
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• 2000

Many researchers have been trying to evaluate the diffusion coefficient of chloride ion in concrete by using qualitative and quantitative electro-migration tests. Up to now, however, there has been no sufficient method to closely determine the diffusion coefficient of chloride ion through electro-migration test. In this paper, the diffusion coefficient of chloride ion in concrete was investigated through an electro-migration test, that is, AASHTO T 277, Dhir's method, Tang's method and Andrade's method. And the results of these test were compared with each other.

• Korea Trade Review
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• v.45 no.1
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• pp.279-300
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• 2020

The cosmetic medical information mobile platform is evolving into a new channel for searching and obtaining relevant information before using cosmetic medical service. In addition, the medical institutions can facilitate the medical contracts, and take advantage of systemic customer management through the cosmetic medical information mobile platform. Therefore, the paradigm of the cosmetic medical mobile service industry is facing a flow of change through the use diffusion of cosmetic medical information mobile platform. In this study, in order to explore the factors affecting the use diffusion of the cosmetic medical information mobile platform, this study used the research model of the influence of the characteristics of the cosmetic medical information mobile platform on perceived convenience and usefulness, and use diffusion by applying TAM(Technology Acceptance Model). As a result, immediateness, interactivity, and customization in the characteristics of cosmetic medical information mobile platform had positive effects on the perceived convenience. Also, interactivity, customization, and economics had positive impacts on perceived usefulness. In addition, perceived convenience and usefulness had positive effects on the use diffusion. Through this study, the factors influencing the use diffusion of cosmetic medical information mobile platform were actually explored, and the service value of the cosmetic medical information mobile platform were categorized. Future research is expected to contribute to the continuous improvement of quality and expansion of the cosmetic medical service market based on various research.

• Computers and Concrete
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• v.10 no.6
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• pp.587-607
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• 2012

The purpose of this research is to propose a design technique of concrete mix proportions satisfying service life through genetic algorithm (GA) and neural network (NN). For this, thirty mix proportions and the related diffusion coefficients in high performance concrete are analyzed and fitness function for diffusion coefficient is obtained considering mix components like w/b (water to binder ratio), cement content, mineral admixture (slag, flay ash and silica fume) content, sand and coarse aggregate content. Through averaging the results of 10 times GA simulations, relative errors to the previous data decrease lower than 5.0% and the simulated mix proportions are verified with the experimental results. Assuming the durability design parameters, intended diffusion coefficient for intended service life is derived and mix proportions satisfying the service life are obtained. Among the mix proportions, the most optimized case which satisfies required concrete strength and the lowest cost is selected through GA algorithm. The proposed technique would be improved with the enhancement of comprehensive data set including wider the range of diffusion coefficients.