• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.111-118
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• 1994

Silicon single crystals were continuously grown by a modified process. Polycrystalline silicon powder was fed from the top reservoir to the growth chamber. Silicon single crystals were grown from the botton of the growth chamber. The balance between the gravitational force of melt and the centrifugal force originated from the rotation of seed was the one of the main factors to control the diameter of crystals grown and quality, etc.

• Journal of Powder Materials
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• v.27 no.2
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• pp.126-131
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• 2020

The grain growth behavior of M-type Sr hexaferrite (SrM) grains is investigated with the addition of MnCO₃. First, the SrM powder is synthesized by a conventional solid-state reaction. The powder compacts of SrM are sintered at 1250℃ for 2 h with various amounts of MnCO₃ (0, 0.5, 1.0, and 4.0 mol%). There is no secondary solid phase in any of the sintered samples. Relative density increases when MnCO₃ is added to the SrM. Obvious abnormal grain growth does not appear in any of the SrM samples with MnCO₃. The average grain size increases when 0.5 mol% MnCO₃ is added to the SrM. However, as the amount of MnCO₃ increase to over 0.5 mol%, the average grain size decreases. These observations allow us to conclude that the growth of SrM grains is governed by the two-dimensional nucleation grain growth mechanism, and the critical driving force for the growth of a grain decreases as the amount of MnCO₃ increases.

• Korean Journal of Environmental Biology
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• v.22 no.4
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• pp.494-500
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• 2004

In order to investigate the effect on morphology of Rhizopus oryzae and production of lactic acid, various interface materials were used. Morphology of fungal showed sheet and flock when resin was added. The production of lactic acid was increased dramatically when interface materials were added. Furthermore, the effect of resin was more significant than that of others. It was assumed that interface materials could absorb substrate and microorganism together, so microorganism was not inhibited by substrate. The effect of static electric field on the interface culture was studied. When the exerting potential was 6.78 voltage, the biomass y was obviously higher than that of zero voltage. A simulated gas-solid interface system was developed to study the growth and two phases model for the growth of Rhizopus oryzae was build up that depended on the symmetric branching theory. An important parameter F was researched. The results indicated that the value of F had obvious difference at exponential and deceleration period, respectively.

• Advances in environmental research
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• v.12 no.2
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• pp.95-111
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• 2023

Pollution, climate change, and waste accumulation are only some of the new problems that have arisen because of the exponential population growth of the past few decades. As the global population expands, managing municipal solid trash becomes increasingly difficult. This is by far the most difficult obstacle for governments to overcome, especially in less developed nations. The improper open dumping of trash, which is causing mayhem across the country, has two immediate effects: it contaminates groundwater and surface water. Air pollution and the accumulation of greenhouse gases are both exacerbated by the release of methane and other harmful waste gases. Leachate from the landfill leaks underground and pollutes groundwater. In most cases, leachate moves into the groundwater zone and pollutes it after forming in association with precipitation that infiltrates via waste. This has far-reaching effects on people's health and disturbs the natural environment. This review article critically examines the current state of Solid Waste Management (SWM), addressing both the highlighted concerns and the government management solutions that have been put in place to address these issues. In addition, the constraints, and difficulties that India will face in the future in terms of solid waste management and the role of models for such a system are discussed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.112-113
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• 2014

The submicron-rods of $Cu_2O$ with diameters of 100-700 nm and lengths of $2-8{\mu}m$ were synthesized by radio frequency magnetron sputtering. The abundance of Cu species, which is modulated by the $Ar/O_2$ ratio during the sputtering process affect directly to the growths of the $Cu_2O$ branches on the bodies of the submicron-rods. Transmission electron microscopy and elemental mapping reveal that metallic Cu are existed on the heads of the $Cu_2O$ rods. The growth rate, catalyst phase and shape reveal that vapor-quasiliquid-solid was the growth mechanism of the formations of those structures.

• Journal of Korea Foundry Society
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• v.33 no.3
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• pp.122-126
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• 2013

Recently, heat-resistant aluminum alloy has been re-focused as a downsizing materials for the internal combustion engines. Heat-resistant Al alloy development and many researches are still ongoing for the purpose of improving thermal stability, high-temperature mechanical strength and fatigue properties. The conventional principle of heat-resistant Al alloy is the precipitation of intermetallic compounds by adding a variety of elements is generally used to improve the mechanical properties of Al alloys. Heat resistant aluminum alloys have been produced by CrW homogeneous solid solution to overcome the limit of conventional heat resistant aluminum alloy. From EPMA, it is found that CrW homogeneous soild solution phases with the size of $50-100{\mu}m$ have been dispersed uniformly, and there is no reaction between aluminum and CrW alloy. In addition, after maintaining at high temperature of 573 K, there is no growth of hardening phase, nor desolved, but CrW still exists as a homogeneous solid solution.

• Journal of Korea Foundry Society
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• v.10 no.1
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• pp.50-56
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• 1990

Continuous casting of the $Al-Al_3Ni$: eutectic composite was carried out by the upward continuous casting process. The morphology of the eutectic growth and the stability of solid-liquid interface were investigated under various growth conditions in an upward continuous casting. The effect of growth conditions on the mechanical properties of the $Al-Al_3$ Ni eutectic composit was also investigated, and the results were compared with those by the Bridgman method. As for the results, it was possible to get the planar solid-liquid interface at the condition of $G_L/R$＝$1.04{\times}10^3^{\circ}Csec/mm^2$. And the inter-rod spacing of $Al-Al_3Ni$ eutectic composite was decreased with the increase of pulling speed. The reduction of inter-rod spacing & value of $G_L/R$ caused the increase of ultimate tensile strength in $Al-Al_3Ni$: eutectic composite. The ultimate tensile strengths of $Al-Al_3Ni$ by the upward continuous casting were higher then those by the Bridgman method.

• KSBB Journal
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• v.28 no.6
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• pp.400-407
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• 2013

The growth characteristics and production of color pigments by Monascus strains were investigated during liquid culture, and production of monacolin K in red mold rice was carried out by solid state fermentation. Four different Monascus ruber strains were cultured in potato dextrose yeast extract broth (PDYB) media at $25^{\circ}C$ for 15 days. The high producing strain for red pigment was not corresponded to the strain for yellow pigment. Production of red pigment was high in the strain causing the fast pH change in culture broth. Production of monacolin K in red mold rice by solid state fermentation was influenced by a combination of wet cell weight and spore density in inoculum by liquid culture. Most strains showed the high production of monacolin K in red mold rice, when submerged fermentation was carried out for 5 days as inoculum for solid state fermentation. These results suggest that submerged fermentation period of inoculum have an effect on the production of monacolin K in red mold rice by solid state fermentation, and monacolin K in red mold rice could be increased by controlling the condition of submerged fermentation for inoculum.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.51-51
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• 2011

We have grown nanocrystalline graphite on sapphire substrate by using solid carbon source molecular beam epitaxy. Changes of structure from amorphous carbon to nanocrystalline graphite controlled by the growth temperature have been investigated by Raman spectroscopy. Raman spectra show D, G, and 2D peaks, whose intensities vary on the growth temperature. Atomic force microscopy reveals that the surface is very flat. Sapphire substrates of different cutting direction produce similar results. Simulations suggest that the interaction between carbon and oxygen causes disorders. Electrical transport measurements exhibit a Dirac-like peak, including a carrier type change by an external gate voltage bias.

• Korean Journal of Materials Research
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• v.29 no.5
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• pp.304-310
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• 2019

Chemical vapor deposition method using $CH_4$ gaseous hydrocarbons is generally used to synthesize large-area graphene. Studies using non-gaseous materials such as ethanol, hexane and camphor have occasionally been conducted. In this study, large-area graphene is synthesized via chemical vapor deposition using polyethylene as a carbon precursor. In particular, we used a poly glove, which is made of low-density polyethylene. The characteristics of the synthesized graphene as functions of the growth time of graphene and the temperature for vaporizing polyethylene are evaluated by optical microscopy and Raman spectroscopy. When the polyethylene vaporizing temperature is over $150^{\circ}C$, large-area graphene with excellent quality is synthesized. Raman spectroscopy shows that the D peak intensity increased and the 2D peak intensity decreased with increasing growth time. The reason for this is that sp3 bonds in the graphene can form when the correct amount of carbon source is supplied. The quality of the graphene synthesized using polyethylene is similar to that of graphene synthesized using methane gas.