• 한국분말재료학회지
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• 제23권4호
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• pp.317-324
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• 2016

Tin is one of the most promising anode materials for next-generation lithium-ion batteries with a high energy density. However, the commercialization of tin-based anodes is still hindered due to the large volume change (over 260%) upon lithiation/delithiation cycling. To solve the problem, many efforts have been focused on enhancing structural stability of tin particles in electrodes. In this work, we synthesize tin nano-powders with an amorphous carbon layer on the surface and surroundings of the powder by electrical wire explosion in alcohol-based liquid media at room temperature. The morphology and microstructures of the powders are characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The electrochemical properties of the powder for use as an anode material for lithium-ion battery are evaluated by cyclic voltammetry and a galvanometric discharge-charge method. It is shown that the carbon-coated tin nano-powders prepared in hexanol media exhibit a high initial charge specific capacity of 902 mAh/g and a high capacity retention of 89% after 50 cycles.

• Journal of Magnetics
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• 제3권3호
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• pp.96-98
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• 1998

In this paper a structurally coupled and magnetically decoupled Ba-ferrite thin film medium is proposed to evade the superparamagnetic limit and reduce media noise. The proposed medium consists of ferrimagnetic Ba-ferrite nano-grains (< 10 nm) and a non-magnetic grain boundary material. Magnetic grains are crystallographically matched with the grain boundary material. Spherical or cubic shaped Ba-ferrite particle is also proposed for above 100 Kfci particulate recording application.

• 한국전산유체공학회지
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• 제18권2호
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• pp.17-25
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• 2013

The process of flow through porous media is of interest a wide range of engineering fields and areas, and the importance of fluid flow with a change in phase arises from the fact that many industrial processes rely on these phenomena for materials process, energy transfer. Especially, the flow phenomena of cryogenic liquid subjected to evaporation is of interest to investigate how the cryogenic liquid behaves in the porous structure. In this study, thermo physical properties, morphological properties of the glass wool with different bulk densities in terms of its temperature-dependence and permeability behaviors under different applying pressure are discussed. Using the experimentally determined properties, characteristics of two main experimental results are investigated. In addition, simulation results are used to realize the cryogenic liquid's flow in porous media, and are compared with experimental results. By using the experimentally determined properties, more reasonable results can be suggested in dealing with porous media flow.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.85.1-85.1
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• 2008

• 한국환경보건학회지
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• 제34권1호
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• pp.101-107
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• 2008

Bio-filtration utilizes microorganisms fixed to a porous medium to metabolize pollutants present in an air stream. The microorganisms grow in a bio-film on the surface of a medium or are suspended in the water phase surrounding the medium particles. Therefore, bio-filter support media play one of the most important key roles in bio-filtration of gas phase pollutants. To characterize and select the appropriate support media, gas adsorption capacity and microorganism immobilization were investigated in lab-scale experiments for the selected target support media which were compost I (compost from lab-scale process), compost II (compost from municipal facility), bark, wood chip, orchid stone and vermiculite. As odor materials, ammonia and trimethylamine were utilized. From the result of experiments, bark was superior to any other support media tested in adsorption capacity as much as 12.5 mg ammonia per 1 g bark. In trimethylamine adsorption, bark and wood chip showed a remarkable results of 21.1 and 14.1 mg/g respectively. On the other hand, microorganism fixation test determined by the count of nitrogen oxidizing microbes population, the compost II and wood chips showed the best results. Considering the characteristics of materials and the operating condition of the bio-filter, bark, wood chip, and compost II are applicable to the support media of bio-filter when they are appropriately blended on the basis of studying the media pH, packing porosity and moisture contents.

• 아동학회지
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• 제25권6호
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• pp.69-87
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• 2004

The purpose of this study was to develop a media literacy program for young children and explore its applicability and effects on young children's media literacy learning. Media literacy, as a concept combined literacy, or the ability to read and write, with media, is about more than just consuming information or understanding technological aspects of media, but is defined as expanded information and communication skills that are responsive to the changing nature of information in human environment. In order to develop media literacy program for young children, the goal and objectives, content areas, teaching methods and materials, and evaluation of media literacy program were searched and established. The subjects of this study consisted of a total of 51 children at age 5-6. The research had been implemented for 8 weeks integrated into daily activities of kindergarten children. Data were collected by interviewing with children using animations, and children-made-cartoons during the pre- and post-tests, and were analyzed quantitatively using rating criteria. The results of this study showed that there were significant differences found in children's abilities to reception, critical thinking, and creativity. This research made a major contribution to provision of a ground for developing an effective media literacy program for young children.

• 한국의상디자인학회지
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• 제8권2호
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• pp.61-71
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• 2006

The purpose of this study is to present a contents production process for costume design analysis by take advantage of the image media of Chinese historical backgrounds. The production process of contents for lectures on fashion design analysis can be summarized as follows: The contents for the design analysis of Chinese costumes can be divided into major media and supplementary media. Major media can be completed through the processes including the selection of Chinese historical backgrounds. images and media (video, DVD title or VOD), verification of image capture parts, image captures, and applications of PPT files. Supplementary media consist of production of analysis materials for each item and TPO, report preparation methods and discussions, and printed matters to be used at the stage of image comparison and verification. This way, a process applicable to the design analysis of Chinese costumes can be presented.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.375-382
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• 2003

Porous media consist of physically and chemically different materials and have an extremely complicated behavior due to the different material properties of each of its constituents. In addition, the internal structure of porous media has generally a complex geometry that makes the description of its mechanical behavior quite complex. Thus, in order to describe and clarify the deformation behavior of porous media, constitutive models for deformation of porous media coupling several effects such as flow of fluids of thermodynamical change need to be developed in frame of Arbitrary Lagrangian Eulerian (ALE) description. The aim of ALE formulations is to maximize the advantages of Lagrangian and Eulerian methods, and to minimize the disadvantages. Therefore, this method is appropriate for the analysis of porous media that are considered for the behavior of solids and fluids. First of all, governing equations for saturated porous media based on ALE description are derived. Then, weak forms of these equations are obtained in order to implement numerical method using finite element method. Finally, Petrov-Galerkin method Is applied to develop finite element formulation.

• 대한가정학회지
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• 제42권3호
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• pp.159-178
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• 2004

The purpose of this study was to investigate the effect of sexual messages in the media on adolescents' attitudes and behaviors toward sex. Subjects of this study consisted of 488 high school students in Cheong-ju City. The findings of this study were as follows; First, sexual messages in the media influenced-adolescents' attitudes toward sex. The more exposure to sexual messages adolescents had more liberal and permissive attitude toward sex. Secondly, sexual messages in the media also effected adolescents' behaviors toward sex, as well. The less sexual messages that they were exposed to, they displayed less sexual relations and behavior. In particular, the number of sexual materials in mass media, variety of sexual messages, and types of school were significant factors in predicting adolescents' sexual intercourse. The research suggested that sexual messages in the media definitely had an effect on adolescents' attitudes and behaviors toward sex. Therefore, it should be encouraged to take advantage of the television V chip and screening software for computers to reduce inappropriate access for adolescents.

• 한국재료학회지
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• 제31권5호
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• pp.286-295
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• 2021

This study attempts to find optimal conditions of the friction coefficient using a discrete element method (DEM) simulation with various friction coefficient conditions and three different grinding media with various ball sizes in a traditional ball mill (TBM). Using ball motion of the DEM simulation are obtained using the optimal friction coefficient compared with actual motion; photographs are taken by the digital camera and the snapshot images are analyzed. In the simulation, the rotation speed of the mill, the materials and velocity of the grinding media, and the friction coefficient between the balls and the wall of the pot are fixed as the actual experimental conditions. We observe the velocity according to the friction coefficient from the DEM simulation. The friction coefficient is found to increase with the velocity. Milling experiments using a traditional ball mill with the same experimental conditions as those of the DEM simulation are conducted to verify the simulated results. In addition, particle morphology change of copper powder is investigated and analyzed using scanning electron microscopy (SEM) for the milling experiment.