• Investigative Magnetic Resonance Imaging
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• v.11 no.2
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• pp.110-118
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• 2007

Purpose: The objective of this work to construct eigenvalue maps that have information of magnitude of three primary diffusion directions using diffusion tensor images. Materials and Methods: To construct eigenvalue maps, we used a 3.0T MRI scanner. We also compared the Moore-Penrose pseudo-inverse matrix method and the SVD (single value decomposition) method to calculate magnitude of three primary diffusion directions. Eigenvalue maps were constructed by calculating of magnitude of three primary diffusion directions. We did investigate the relationship between eigenvalue maps and fractional anisotropy map. Results: Using Diffusion Tensor Images by diffusion tensor imaging sequence, we did construct eigenvalue maps of three primary diffusion directions. Comparison between eigenvalue maps and Fractional Anisotropy map shows what is difference of Fractional Anisotropy value in brain anatomy. Furthermore, through the simulation of variable eigenvalues, we confirmed changes of Fractional Anisotropy values by variable eigenvalues. And Fractional anisotropy was not determined by magnitude of each primary diffusion direction, but it was determined by combination of each primary diffusion direction. Conclusion: By construction of eigenvalue maps, we can confirm what is the reason of fractional anisotropy variation by measurement the magnitude of three primary diffusion directions on lesion of brain white matter, using eigenvalue maps and fractional anisotropy map.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1697-1699
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• 2004

In this investigation, we have studied the diffusion of the $Cu^+$ ion in the Cu/Ta/SiOCH/Si and Cu/Ta/$SiO_2$/Si MIS-C structure. The Cu ions diffusion into the Ta barrier and SiOCH was examined by shift in flatband voltage of capacitance-voltage measurement and leakage current of current-voltage measurement. These evalution indicated that $Cu^+$ ion diffusion rate in Ta/SiOCH is considerably lower then the Ta/$SiO_2$ structure. And diffusion barrier Ta(50[nm]) is useful barrier against $Cu^+$ ion diffusion up to 450$^{\circ}C$.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.6
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• pp.725-736
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• 2013

This study segments information users according to depth and variety of use diffusion in order to differentiate between the influence of fashion information spread and diffusions from each segmented group. Data were collected from a fashion community to perform a social network analysis that used UCINET 6.0. Members completed the survey materials and the network materials were utilized in the analysis to test the hypothesis. The segmented groups of information users determined the study results according to use diffusion and the variables that affect them. The variables affecting information diffusion outcomes indicate different significant influence factors on each segmented market. Information variety and complexity represents elevated information reproductions and verbal acceptances from information diffusion outcomes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.141-148
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• 2005

The nonlinear humidity distribution occurs due to the moisture diffusion when a concrete is exposed to an ambient air. This nonlinear humidity distribution induces shrinkage cracks on surfaces of the concrete. Because shrinkage cracks largely affect the durability and serviceability of concrete structures, the moisture diffusion in concrete must be investigated. The purpose of this paper is to propose a model of the moisture diffusion coefficient that governs moisture diffusion within concrete structures. To propose the model, numerical analysis was performed with several experiments. Because the moisture diffusion coefficient is changed with aging, especially at early ages, the proposed model includes aging effect by terms of the porosity as well as the humidity of concrete.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.101-106
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• 2004

In this paper, a blood vessel in an angiographic image, which plays an importance role in the diagnose diseases including in the eyes, brain and heart, is enhanced by using a directed diffusion technique. A fundamental component of the angiographic analysis is vessel segmentation that the proposed method provides a preprocessing of the image into a form suitable for human analysis, or more importantly, for machine analysis such the segmentation. Vessel enhancement is a challenging problem due to the complex nature of vascular trees and to imaging imperfections. Some parts of the inherent imperfections in angiography are the intensity inhomogeneity between the larger and smaller vessels, and another imperfection is the leakage of contrast agent into the background tissue that provides to low contrast between vessels and tissue. In the proposed scheme, the directed diffusion solves the problem by formulating a local geometric structure, which consists of direction and scale of the blood vessels. The diffusion process uses the local structure to enhance by a diffusivity tensor. The proposed algorithm can be applied to maintain sharpness and coherence-smooth the intra-regions into homogeneity better than traditional diffusion methods, which are Gaussian regulation and coherence enhancing diffusion.

• International Journal of Concrete Structures and Materials
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• v.4 no.2
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• pp.109-112
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• 2010

Part I of this study was devoted to the electrical accelerated chloride diffusion in mortars. In this second part, natural chloride diffusion has been investigated for four types of mortars under exposure to a 0.5 mol/L NaCl solution for a period of up to 35 days. Two different types of sand were used for the production of test samples: siliceous sand (used as a reference) and limestone sand (used in this study). The effect of water to cement ratio and exposure time on the diffusion coefficients of mortars was also investigated. In this study, the total and free chloride content and penetration depth of mortar were measured after immersion, and Fick's second law of diffusion was fitted to the experimental data to determine the diffusion coefficient. Their results show that the use of crushed limestone sand in mortar had a positive effect on the chloride resistance. The apparent diffusion coefficient in all specimens was smaller than that in siliceous sand mortar. However, the chloride penetration of these mortars was increased as exposure time progressed.

• IE interfaces
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• v.25 no.3
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• pp.327-337
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• 2012

The development of information and communication technology affects people's life in social, cultural, and economic aspects. When this happens in public sector, it gives way more benefits than in private sector because of its high accessibility by public. Among the technological public services in Korea, call center service which provides administrative services by telephone and internet had been spotlighted as a new type of communication between people in demand and public service provider. Public call center service is expected to be continuously diffused in years due to its accessibility and convenience for public users. This study analyzes diffusion pattern of public call center service in Korea using Bass model and tries to suggest appropriate diffusion strategies. For practical cases, three most popular public call centers in Korea are analyzed in light of diffusion pattern and operating strategies. Our analyses identify that public call centers in Korea are facing continuous diffusion in two years and there exist certain strategies to efficiently expedite the diffusion.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.2
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• pp.48-60
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• 2016

Accurate simulation of free-surface wave flows around a ship is very important for better hull-form design. In this paper, a computational fluid dynamics (CFD) code which is based on the open source libraries, OpenFOAM, was developed to predict the wave patterns around a ship. Additional anti-diffusion source term for minimizing a numerical diffusion, which was caused by convection differencing scheme, was considered in the volume-fraction transport equation. The influence of the anti-diffusion source term was tested by applying it to free-surface wave flow around the Wigley and KCS model ships. In results, the wave patterns and hull wave profiles of the Wigley and KCS model ships for various anti-diffusion coefficients showed quite close patterns. While, the band width of the water volume-fraction values between 0.1 to 0.9 at the Wigley and KCS model hull surfaces was narrowed by considering the anti-diffusion term. From the results, anti-diffusion source term decreased free-surface smearing.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.22-33
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• 2015

Chloride ions in RC (Reinforced Concrete) structures can cause very severe corrosion in reinforcement steel. It is generally informed that chloride penetration can be considerably accelerated by enlarged chloride diffusion due to cracks. These cracks play a role in main routes through which chloride ions penetrate into the concrete, and also lead to steel corrosion in RC structures exposed to chloride attack, such as port and ocean structures. In this paper, field survey including evaluation of crack and chloride concentration distribution in concrete is performed to investigate an effect of crack on chloride diffusion. The service life of cracked concrete exposed to the marine environmental condition is estimated considering the crack effect on chloride diffusion. For this purpose, diffusion coefficients in cracked concrete are obtained based on the field survey. Using the relationship between diffusion coefficients in the cracked concrete and the crack widths, service life of the cracked concrete is predicted in a probabilistic framework. A bimodal distribution with two peaks, consisting of a weighted sum of two normal distributions is introduced to describe chloride diffusion of the concrete wharf with crack.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.165-172
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• 2011

Wireless sensor networks consist of small battery powered devices with limited energy resources. Once deployed, the small sensor nodes are usually inaccessible to the user, and thus replacement of the energy source is not feasible. Hence, energy efficiency is a key design issue that needs to be enhanced in order to improve the life span of the network. Directed Diffusion is a well known routing protocol. In this paper we adopt the clustering mechanism to improve the efficiency of Directed Diffusion. We introduce C-Directed Diffusion which make clusters, select the CH(Cluster Head) and CHs do the same process as in Directed Diffusion. C-Directed Diffusion is pretty simple and show better performance than Directed Diffusion.