• Journal of the Korean Ceramic Society
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• v.23 no.5
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• pp.47-54
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• 1986

The structures of crystalline vitreous and liquid $SiO_2$ were Monte carlo simulated employing the potential energy function comprising Lennard-Jones 2-body and Axilrod-Teller 3-body potentials. Although the Si-O-Si angular distribution functions obtained in the simulation appear to be higher than the experimental results the other simulation results including SiO, O-O and Si-Si radial distribution functions and O-Si-O anglular distribution functions agree well with experimental data within acceptable limits. Themost important outcome in this study is that various $SiO_2$forms were successfully reproduced with the same potential energy function.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.608-613
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• 2004

Mechanical properties of hypereutectic Al-Si alloy are influenced by the size and distribution of primary Si. To investigate the effects of P addition and holding time, hypereutectic Al-Si alloys with various amount of P content were produced in the lab. Then, the size and distribution of primary Si were examined respectively. Mechanical properties of hardness, tensile strength and wear resistance were analyzed in conjunction with the microstructural variations in alloys.

• Journal of Korea Foundry Society
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• v.28 no.1
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• pp.25-30
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• 2008

To develop a functionally graded microstructure of cylindrical liner, effect of centrifugal casting parameters such as pouring temperature of hyper-eutectic Al-Si alloy melt, mold pre-heating temperature, and rotational frequency of mold on distribution of primary Si particles across wall thickness were investigated. Segregation tendency of Si particles toward inner side of cylindrical liner increased as the increase of rotational frequency of mold, pouring temperature of melt and mold pre-heating temperature. Especially, distribution density of primary Si particles within 1.5 mm from inner surface of cylindrical liner was above 35% under the centrifugal casting condition of $750^{\circ}C$ melt pouring temperature, $300^{\circ}C$ mold pre-heating temperature, and 2500 rpm mold rotational frequency.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.71-74
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• 2012

Uniformity of the wafer temperature is one of the important factors in etching process. Plasma, chucking force, backside helium pressure and the surface temperature of ESC(electrostatic chuck) affect the wafer temperature. ESC consists of several layers of structure. Each layer has own thermal resistance and the Si-adhesive layer has highest thermal resistance among them. In this work, the temperature distribution of ESC was analyzed by 3-D FEM with various defects and the thickness deviation of the Si-adhesive layer. The result with Si-adhesive layer with the low center thickness deviation shows modified temperature distribution of ESC surface.

• Environmental Analysis Health and Toxicology
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• v.23 no.2
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• pp.139-141
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• 2008

Tissue distribution of $SiO_2$ nanopaprticles was investigated in mice after oral administration or skin treatment. ICR Male mice were treated with $SiO_2$ nanoparticles 2.5 g/kg/day for five consecutive days and sacrificed at 24 hours after the last administration. As results, the orally administered $SiO_2$ nanoparticels were distributed in the testis and kidney but not in lung at 24 hours after the last treatment. In case of skin treatment, $SiO_2$ nanoparticles were distributed to lung as well as testis, brain, kidney and liver. The results suggested that $SiO_2$ nanoparticles (12 nm) are easily absorbed through entero-gastric system or skin.

• Journal of Powder Materials
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• v.1 no.1
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• pp.66-71
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• 1994

Optical microstructures and mechanical properties of Na gas atomized Al-20Si-5Fe alloying powder and its hot extrudates were studied on 3 different types of powder size distribution. This powder showed the size distribution of 10~210 $\mu\textrm{m}$. Also the microstructures of $\alpha$-Al, primary and eutectic Si and needle shaped intermetallic compounds were observed by optical microscope. These needle shaped intermetallic compounds were identified as ${\delta}Al_4FeSi_2$- by XRD and EDX analysis. The ultimate tensile strength(UTS) of these alloy extrudates was increased from 324 to 390 MPa with decreasing powder size range from 120~210 $\mu\textrm{m}$ to 10~64 $\mu\textrm{m}$. A value of Micro-vic-kers hardness was simillar to the result of UTS. These extrudates showed better wear resistance than those of Al-20Si-2X(X : Ni, Cr, Zr), although they are insensitive to the size distribution. These results indicate that the presentation of ${\delta}Al_4FeSi_2$ intermetallic compounds contributed to the wear resistance improvement.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.21-29
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• 1999

The effects of density and pore size distribution of substrate in preparing SiC conversiton layer on graphite substrate were investigated. The chemical reaction for formation of SiC conversion layer was occurred at substrate surface or below surface through SiC gas infiltration. It was supposed that the pore size distribution required for the sufficient SiO gas infiltration and the continuous chemical reaction during conversion process was in the range of 1.0∼10.0$\mu\textrm{m}$. In the stress analysis of SiC layer with finite element method (FEM), the residual stress distribution due to thermal mismatch was shown. However, the compressive stress was measured in SiC layer by X-ray diffraction, it was presumed that the residual stress distribution of SiC layer was mainly influenced by the constraining effect of interlayer between SiC layer and graphite substrate, and the densification behaviro and the grain growth in SiC conversion layer.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.85-86
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• 2006

A theoretical model is applied to the analysis of thermomechanical properties of $Al-SiC_p$ FGMs in this study. Functionally graded $Al-SiC_p$ composites ($Al-SiC_p$ FGMs) consisted with 10 layers gradually changing volume fractions of Al and $SiC_p$ were fabricated using the pressureless infiltration technique. $Al-SiC_p$ FGMs plates of total thickness of 3mm, 5mm and 7mm with fairly uniform distribution and compositional gradient of $SiC_p$ reinforcement in the Al matrix throughout the thickness was successfully fabricated. The curvature of $Al-SiC_p$ FGM plates was measured to check the internal stress distribution predicted via a theoretical model for the analysis of thermo-mechanical deformation. The evolution of curvature and also internal stresses in response to temperature variations could be predicted for the different combinations of geometric thickness of FGM plates. Theoretical prediction of thermally induced stress distribution makes it possible to design FGM structures without any critical failure during the usage of them.

• Journal of Distribution Science
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• v.21 no.1
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• pp.45-52
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• 2023

Purpose: This study aims to analyze the confirmation the purchase decision of community enterprise products, such information is an important issue for community enterprise entrepreneurs to develop a marketing strategy through the purchasing decision of community enterprise products Research design, data and methodology: The research was designed by using mixed methods research (exploratory design), starting with in-depth interviews of consumers of community enterprise products to determine the reasons for their purchase decisions. The researcher then used the data from the in-depth interviews to create a questionnaire for consumers of community enterprise products. These data were used to analyze the confirmation components of such elements. Results: The analysis found the following. 1. Decision-making is based on a product 2. Decision-making is based on social context considerations Conclusions: Develop an image to make a difference between community enterprise entrepreneurs and general entrepreneurs for distribution. The local wisdom, it is a local intellectual resource. It should be used in adjusting or blending old knowledge with new knowledge together appropriately. Creating community participation, love, unity, and the sympathy of the people in the community can help in participation in the operation of community enterprises.

• Nuclear Engineering and Technology
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• v.38 no.7
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• pp.675-680
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• 2006

The neutron transmutation doping of silicon (NTD), as a method to produce a high quality semiconductor, utilizes the transmutation of a silicon element into phosphorus by neutron absorption in a silicon single crystal. In this paper, we present the design of a neutron screen for a 6' Si ingot irradiation in the NTD2 hole of HANARO. The goal of the design is to achieve an even flat axial distribution of the resistivity, or $Si^{30}(n,{\gamma})Si^{31}$ reaction rate, in the irradiated Si ingot. We used the MCNP4C code to simulate the neutron screen and to calculate the reaction rate distribution in the Si ingot. The fluctuations in the axial distribution were estimated to be within ${\pm}2.0%$ from the average for the final neutron screen design; thus, they satisfy the customers' requirement for uniform irradiation. On the other hand, we determined the optimal insertion depths of the Si ingots by varying the critical control rod position, which greatly affects the axial flux distribution.