• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.506-511
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• 2006

Silver is one of the most appropriate Jewelry materials for Jewelry casting and bench working. The technique known as 'Mokumegane' is good for making silver jewelry with natural patterns, such as wood grain patterns, but the process is not easy for silversmithing because it requires complicated and heavy labour. Instead of using conventional Mokumegane technique, we propose a new modified silver-copper casting process that enables a similar surface effect with good metal bonding strength between silver and copper. Simply pouring the molten silver into pre-aligned copper granules or 0.5 mm to 1.5 mm-thick copper sheets leads to well embedded copper silver ingots. The rolled silver plates from those ingots show excellent bonding interface even after the silver plate rolled ten times. We successfully fabricated prototype rings with copper embedded silver plates. Our result implies that our newly proposed process nay be a simpler way to fabricate silver jewelry with a pseudo-Mokumegane effect.

• Journal of Powder Materials
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• v.24 no.3
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• pp.210-215
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• 2017

In this study, STS316L powders prepared by gas atomization are used to manufacture bulk structures with dimensions of $10{\times}10{\times}10mm^3$ using selective laser melting (SLM). The microstructures and hardness of the fabricated 316L stainless steel has been investigated with the laser beam overlap varied from 10% to 70%. The microstructures of the fabricated STS316L samples show a decrease in the balling and satellite of powders introducing defect in the bulk samples and the porosity caused by the gap between the molten metal pools disappearing as the overlap ratio increases, whereas a low overlap ratio results in significant balling and a large amount of isolated powders due to the increased gap between the melt pools. Furthermore, the highest value in Vickers hardness is obtained for the sample fabricated by 30% overlapped laser beams. These results show that the overlap ratio of laser beams in the SLM process should be considered as an important process parameter.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.309-313
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• 2018

In this study, we prepared Li-K-Cd alloy, which meets the requirement of eutectic ratio of Li:K, to maintain the operating temperature of the drawdown process at $500^{\circ}C$ and to achieve the reuse of LiCl-KCl molten salt. The prepared Li-K-Cd alloys were added to LiCl-KCl salt bearing U and Nd at $500^{\circ}C$ to investigate the removal of $UCl_3$ in the salt. The reduction of $UCl_3$ in the salt was examined by measuring the OCP value of salt and analyzing the salt composition by ICP-OES. Reduction was also visually confirmed by change of salt color from dark purple to white. The experimental results reveal that the prepared Li-K-Cd alloy has reductive extractability for $UCl_3$ in salt. By improving the preparation method, the Li-K-Cd alloy can be applied to the drawdown process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.3
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• pp.325-335
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• 1994

The spinel $MgO.Al_20_3$ single crystals were grown by FZ (floating zone) method. Its melting point is about, $2135^{\circ}C$ and is important to the process of the growth from the melt. There have been some reports of the growth by Czochralski and Verneuil method. However, this study is the first trial to the spinel crystal with the application of FZ method. In this study, $MgAl_2O_4$ spinel crystals were grown by using FZ method which uses the ellipsoidal mirror furnace having infrared halogen lamps as a heat source. With dopants of transition metal ions, it was possible to melt the feed rod which does not absorb the infrared rays due to the transparent properties to infrared ray of spinel itself and the red, green and blue colored spinel single crystals could be grown more easily. As a conclusion, the purpose of this study is to find the spinel single crystal growth mechanism with respect to th growth interfaces and molten zone stability and to characterize the state of growth resulting from the concavity to the melt of interfaces.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.248-257
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• 2020

This study presents an initial design for a novel system consisting in a coupled nuclear reactor and a phase change material-based thermal energy storage (TES) component, which acts as a buffer and regulator of heat transfer between the primary and secondary loops. The goal of this concept is to enhance the capacity factor of nuclear power plants (NPPs) in the case of high integration of renewable energy sources into the electric grid. Hence, this system could support in elevating the economics of NPPs in current competitive markets, especially with subsidized solar and wind energy sources, and relatively low oil and gas prices. Furthermore, utilizing a prismatic-core advanced high temperature reactor (PAHTR) cooled by a molten salt with a high melting point, have the potential in increasing the system efficiency due to its high operating temperature, and providing the baseline requirements for coupling other process heat applications. The present research studies the neutronics and thermal hydraulics (TH) of the PAHTR as well as TH calculations for the TES which consists of 300 blocks with a total heat storage capacity of 150 MWd. SERPENT Monte Carlo and MCNP5 codes carried out the neutronics analysis of the PAHTR which is sized to have a 5-year refueling cycle and rated power of 300 MW_th. The PAHTR has 10 metric tons of heavy metal with 19.75 wt% enriched UO₂ TRISO fuel, a hot clean excess reactivity and shutdown margin of $33.70 and -$115.68; respectively, negative temperature feedback coefficients, and an axial flux peaking factor of 1.68. Star-CCM + code predicted the correct convective heat transfer coefficient variations for both the reactor and the storage. TH analysis results show that the flow in the primary loop (in the reactor and TES) remains in the developing mixed convection regime while it reaches a fully developed flow in the secondary loop.

• Journal of Welding and Joining
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• v.29 no.3
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• pp.58-63
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• 2011

Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was compared with existing CP-type nozzle by TIG pulse welding in overhead position. As a result, CP-type occurs the wormholes in the overhead position, but the Venturi-type without the pore and formed a good bead appearance.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.22-22
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• 2010

Eutectic composition phase with low melting point which solidifies at the final stage affects the solidification cracking at the intercellular or interdendritic area of welds and castings. If sufficient amount of eutectic composition liquid does not exist between the solidifying phases, the discontinuities remain as cracks. However, abundant amount of liquid eutectic composition existing in the final stage can flow into the discontinuities easily and heal the cracks. By flowing of liquid eutectic and healing of discontinuities, the possibility of cracking can be reduced when the amount of eutectic liquid is sufficient. For the solidification of pure metals, liquid eutectic does not exist and the interlocking of growing solid phases can be realized without interruption of liquid film. Therefore there is little possibility of solidification cracking in the case of welds and castings of pure metal. In a practical sense, the effective way to reduce or prevent the solidification cracking is making the composition of molten pool or melts near to the eutectic composition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.986-989
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• 2003

In the steel production line, the molten metal of a furnace is transformed into slab material and then move to the hot strip line, This paper describe about the real time recognition system of material management number, which is marked at the surface of a slab in the steel production line. This recognition processing should be performed before the slab is moved to the hot strip line. This system include following recognition steps. First, we remove noise from the captured slab image by use pre-filter. Second, we extract rough area, which is include slab number and then, we extract individual number area. Finally, we recognize material management number by use KLT(Karhunen-Loeve transform) algorithm. We applied our system to the real slave image, which was captured in the process line. In the results, we recognized slave number to the 94% accuracy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.310-319
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• 2012

In order to investigate the biological effects of conformational changes in the folding state of bovine ${\alpha}$-lactalbumin (${\alpha}$-La), the protein was prepared and classified as apo form, microbial transglutaminase (MTGase) added form, or bovine ${\alpha}$-La made lethal to tumor cell (BAMLET) form. Apo ${\alpha}$-La form showed weaker cancer cell inhibitory activity (apoptosis) than native ${\alpha}$-La, which suggests that the metal ion-like $Ca^{2+}$ had a positive effect, whereas BAMLET form showed strong cancer cell apoptotic activity. The BAMLET form seemed to be a molten globule structure that increased hydrophobicity. MTGase added to apo ${\alpha}$-La polymer showed similar anti-cancer activity as native ${\alpha}$-La, and it was well hydrolyzed by digestive enzymes. NMR results showed that BAMLET interacted with oleic acid and produced a complex.

• Journal of Korea Foundry Society
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• v.25 no.5
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• pp.195-202
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• 2005

In this study, we investigated the effect of Sb/RE on the microstructure and mechanical properties of as-cast heavy sectioned, over 250mm thickness, ferritic ductile cast iron. Exothermic and thermal insulation material were equipped on the wall of sand cast mold having the dimensions of $250{\times}250{\times}250$ mm. The nominal composition of the molten metal was controlled to be on the eutectic composition and Sb was added about 0, 0.005 and 0.02% respectively. In the center of as-cast ingot without Sb addition, the solidification of chunky graphite was induced by the eutectic reaction that took long time, which caused the decrease of elongation and impact energy. In case that the value of Sb/RE is 0.8, the solidification of chunky graphite could be suppressed and the improvement of nodularity was observed. On the other hand, the excessive addition of Sb suppressed the solidification of chunky graphite but gave rise to the solidification of flake graphite and the increase of pearlite contents. This results in poor elongation and impact energy which is lower than those in the case of no Sb addition.