• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.24-31
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• 2019

The current study demonstrates an efficient procedure to create ingots from $Al_2O_3$ powder using the skull melting method to use these ingots as a starting material in conventional methods for growing synthetic single-crystal sapphire. Dimension of the cold crucible was 24 cm in inner diameter and 30 cm in inner height, 15 kg of $Al_2O_3$ powder was completely melted within 1 h at an oscillation frequency of 2.75 MHz, maintained in the molten state for 3 h, and finally air-cooled. The areal density and components of the cooled ingot by parts were analyzed through scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The areal density and $Al_2O_3$ content of the ingot were related to the temperature distribution inside the cold crucible during high-frequency induction heating, and the area with high temperature was high tends to be high in areal density and purity.

• Environmental Engineering Research
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• v.8 no.3
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• pp.130-140
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• 2003

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.90-90
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• 2008

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.202-202
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• 2007

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.83.1-83.1
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• 2003

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.248-251
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• 2003

The large size grain of poly-Si film is obtained above the upper limit of excimer laser energy at which the random nucleation occurs. We simulate the time dependent temperature profile of ${\alpha}-Si/SiO_2/Si$ substrate structure according to the excimer laser energy with $ANSYS^{\circledR}$ simulator. As the thickness is increased, the laser energy for the melting of ${\alpha}-Si$ film is increased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.35-37
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• 1998

This study was performed to investigate lipid content, melting point, refractive index, fatty acid composition and energy intake from lipid of commercial fried instant noodles. Sixty five samples were collected in Seoul area, and analyzed. The average of lipid content was 16.7%, melting point and refractive index were 29$^{\circ}C$ and 1.46, respectively. The fatty acid composition mainly consisted of C16:0, C18:1 and C18:2. The ratio of P/M/S in fried instant noodles was 0.19 : 0.77 : 1.00. The average energy intake from lipid of 100g fried instant noodles was 150.3kcal.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.42-51
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• 2021

Investigations of process parameters are essential when fabricating high-quality parts using additive manufacturing. This study investigates the change in the mechanical characteristics of a SUS316L specimen fabricated using selective laser melting based on the energy density and bead overlap ratio. The SUS316L powder particles were spherical and 35 ㎛ in size. Single-bead and hexahedral shape deposition experiments were performed sequentially. A single bead experiment was performed to obtain the bead overlap ratios for different laser parameters utilizing laser power and scan speed as experimental parameters. A hexahedral shape deposition experiment was also performed to observe the difference in mechanical properties, such as the internal porosity, surface roughness, and hardness, based on the energy density and bead overlap ratio of the three-dimensional printed part. Laser power, scan speed, overlap ratio, and layer thickness were chosen as parameters for the hexahedral shape deposition experiment. Accordingly, the energy density applied for three-dimensional printing, and the experimental parameters were calculated, and the energy density and bead overlap ratio for fabricating parts with good properties have been suggested.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.945-956
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• 1999

This work reports a set of approximate analytical solutions describing the initial transient process of close-contact melting between a rectangular parallelepiped solid and a flat plate on which either constant temperature or constant heat flux is imposed. Not only relative motion of the solid block tangential to the heating plate, but also the density difference between the solid and liquid phase is incorporated in the model. The thin film approximation reduces the force balance between the solid weight and liquid pressure, and the energy balance at the melting front into a simultaneous ordinary differential equation system. The normalized model equations admit compactly expressed analytical solutions which include the already approved two-dimensional solutions as a subset. In particular, the normalized liquid film thickness is independent of all pertinent parameters, thereby facilitating to define the transition period of close-contact melting. A unique behavior of the solid descending velocity due to the density difference is also resolved by the present solution. A new geometric function which alone represents the three-dimensional effect is introduced, and its properties are clarified. One of the representative results is that heat transfer is at least enhanced at the expense of the increase in friction as the cross-sectional shape deviates from the square under the same contact area.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.533-540
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• 2014

Recently, latent heat thermal energy storage system (LHTES) has gained attention in order to utilize middle temperature (373~573 K) waste heat from biomass gasification. This paper has investigated thermo-physical properties of erythritol [$CH_2OHCHOH$ $CHOHCH_2OH$], mannitol [$CH_2OH$ $(CHOH)_4CH_2OH$] and their compounds as phase change materials (PCMs). The differential scanning calorimetry (DSC) was applied to measure the melting point and latent heat of these PCMs. Also the melting and solidification characteristics of these PCMs were observed in a glass tube with a digital camera. In the DSC measurement, when the amount of mannitol content was more than 40 mass%, the melting point of these compounds show two melting points. The experimental results showed that the velocity of melting and solidification were different for every mixture ratio of compounds. These compounds had the super-cooling phenomenon during the solidification process.