• The Korean Journal of Food And Nutrition
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• v.28 no.6
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• pp.1026-1032
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• 2015

This study attempted to find an efficient method for the preparation of high-purity galactooligosaccharides (HP-GOS) using ${\beta}$-galactosidase and yeast fermentation. GOS prepared using Lactozym 3000L showed the greatest enhancement in total GOS of the six ${\beta}$-galatosidases tested. GOS alone achieved 51% conversion of initial lactose. GOS production was enhanced by fermentation with commercial yeast (Saccharomyces cerevisiae); its concentration reached 71% after 36h fermentation with 8% yeast. Component sugar analysis with HPLC indicated that HP-GOS fermented with S. cerevisiae showed significantly increased levels of 4'/6'-galactosyllactose and total GOS as well as a significantly decreased glucose level. HP-GOS facilitated the growth of Lactobacillus sp. (L. acidophilus and L. casei) and Bifidobacterium sp. (B. longum and B. bifidum). In sum, high-purity GOS has been successfully produced through both an enzymatic process and yeast fermentation. GOS encourages the growth of bacteria such as Lactobacillus and Bifidobacterium that may be beneficial to human gastrointestinal health.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.523-528
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• 2015

In this study, we investigated the effects of sulfuric acid on the synthesis of calcium borate in the artificial boron-containing brine (bittern) saturated with calcium hydroxide. For the study, we attempted to synthesize calcium borate under various conditions such as reaction temperature, reaction time, and cooling temperature after heating, and then to examine the recovery and purity of the calcium borate according to the presence or absence of sulfuric acid at each condition. The XRD analysis confirmed that, regardless of the presence of sulfuric acid, the calcium borate ($Ca_2B_2O_5{\cdot}H_2O$) was synthesized, while, in the presence of sulfuric acid, the calcium sulfate ($CaSO_4{\cdot}0.5H_2O$) was produced as a by-product. In all the experiments performed by varying the reaction temperature and time, the recovery and purity of the calcium borate without sulfuric acid were observed higher than those with it. The results indicated that the addition of sulfuric acid increased the solubility of the calcium hydroxide, but the calcium sulfate produced as a by-product could decrease the recovery and purity of the calcium borate by preventing the synthesis. In this study, the artificial boron-containing brine (bittern) (500 mg-B/L) was saturated with calcium hydroxide in the absence of sulfuric acid, and then the solution was heated at $80-105^{\circ}C$ for less than 10 minutes to synthesize the calcium borate. The recovery and purity of calcium borate were measured as high as 80 % and 96 %, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.588-595
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• 2020

This study examined the catalytic property of Ni-catalyst used in the gas purifying process to manufacture inert gases of N2 and Ar with high-purity over 9N for semiconductor industrial applications. Two types of Ni-catalysts with a cylindrical shape (C1) and churros shape structure (C2) were compared for the assessment. Optical microscopy and FESEM were used to analyze the shape and microstructure of the Ni-catalyst. EDS, XRD, and micro-Raman characterization were performed to examine the composition and properties. BET and Pulse Titration analyses were conducted to check the surface area and catalytic property of the Ni-catalyst. From the composition analysis results, C1 contained a relatively large amount of graphite as an impurity, and C2 contained higher Ni contents than C1. From specific surface area analysis, the specific surface area of C2 was approximately 1.69 times larger than that of C1. From catalytic property analysis, outstanding performance in O₂ and CO impurity removal was observed at room temperature. Therefore, C2, having low-impurity and large specific surface area, is a suitable catalyst for the high-purity inert gas process in the semiconductor industry because of its outstanding performance in O₂ and CO impurity removal at room temperature.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.621-623
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• 2015

This article describes a purification method yielding high purity of MFB produced from DMT production process. Aldehyde functional group of MFB included in side-products were converted to acetal compound via reacting with methanol and further separated. Hydrolysis process of the acetal product was continued under acidic condition and highly pure MFB were obtained with 90% yield. The structure of MFB was analyzed by $^1H$ NMR and $^{13}C$ NMR spectroscopy. Also, the purity of MFB was estimated to be over 99% by GC analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.41-47
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• 2024

In this study, the resistance characteristics of semi-insulating SiC single crystals grown using the PVT method were investigated, considering the purity level of SiC source powders used in PVT growth and the cooling procedure after crystal growth. Two β-SiC powders with different purities were employed, and the cooling rate after growth was adjusted to achieve various resistance values. 4-inch HPSI-SiC ingots were grown using the PVT method, utilizing SiC powders with low nitrogen concentration and relatively high nitrogen concentration. These ingots were then subjected to different cooling procedures to modify the cooling rate. Transmission/absorption spectra and crystal quality of the grown crystals were analyzed through UV/VIs/NIR spectroscopy and X-ray rocking curve analysis, respectively. Additionally, electrical properties were investigated through non-contact resistivity analysis to identify the dominant factors influencing resistivity properties.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.81-88
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• 2016

Limonene is orange flavored natural material that is mainly contained in mandarine and lemon peels. D-limonene was extracted from cold-storaged mandarine peel by using Soxhlet extractor at $120^{\circ}C$ for 2 hours with ethanol as solvent. Henry constants of d-limonene and impurity were calculated as $H_{Lim}=8.55$ and $H_{imp}=0.223$ from the result of HPLC analysis. 4-bed SMB of limonene simulation with $0.46{\times}25cm$ columns was conducted by using Aspen chromatography program. Then effective condition for purity was found by changing $m_2$ and $m_3$ values in triangle diagram. The highest purity was 98.59% at $m_2=2.57$, $m_3=9.55$. For this case, feed, desorbent, extract, and raffinate flow rates were 1 mL/min, 1.19 mL/min, 0.857 mL/min and 1.34 mL/min, respectively. Scale-up simulation was also conducted by increasing column diameter from 0.46 cm to 1.6 cm for getting the same efficiency. The increased flow rates were 12 mL/min, 14 mL/min, 10 mL/min, and 16 mL/min for feed, desorbent, extract, and raffinate. It was possible to scale-up with maintaining same limonene purity because linear isotherms of limonene and impurity were assumed.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.78-83
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• 2022

REBCO coated conductors are widely used for HTS power application, high magnetic field magnet application, and etc. A thermal stability of the REBCO conductor is essential for the operation of HTS-based device, and thermal conductivities of the conductor are relevant parameters for modeling cryogenic heat transfer. REBCO conductors consist of a REBCO layer, copper layers for electrical stabilization and a hastelloy substrate. At cryogenic temperature, thermal conductivity of copper and silver strongly depend on the purity of the material and the intensity of the magnetic field. In this study, thermal conductivities of the laminated composite structure of REBCO conductor are evaluated by using the thermal network model and the multidimensional heat conduction analysis. As a result, the thermal network model is applicable to REBCO conductors configured in series or parallel alone and multidimensional heat conduction analysis is necessary for complex cases of series and parallel configuration.

• Archives of Pharmacal Research
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• v.26 no.12
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• pp.997-1001
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• 2003

This paper deals with chiral enzymatic resolution of 4-arylthio-2-butanols by lipase to prepare potential intermediates of $\beta$-lactam antibiotics. Among several lipases employed, lipase P type enzyme gave the highest ee value to prepare (R)-4-arylthio-2-butyl acetate. The enzymatic resolution of phenyl substituted alcohol (6a) using lipase P showed the highest ee value (99.7%) among those of 4-arylthio-2-butanol derivatives. Lipase P mediated hydrolysis of acylester 7a gave also (R)-alcohol 6a selectively. For determination of enantiomeric purity of these enzymatic resolved analytes, liquid chromatographic analysis was performed using two coupled Chiralcel OD and (R,R)-WhelkO chiral column.

• Resources Recycling
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• v.3 no.3
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• pp.21-26
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• 1994

In present study an attempt has been made to extract the high purity $Al_2O_3$from domestic aluminous shale. The processes of the salt roasting with ammonium sulfate, extraction with sulfuric acid and calcination were adopted. In the extraction of alumina, the effects of the sulfuric acid concentration, the reaction time and the temperature has been investigated. The reaction products were analyzed by X-ray diffraction, DTA-TG, chemical analysis and SEM. The results are summerized as follows: 1)The pretreatment conditions were 0.6M-$(NH_4)_2SO_4$and $650^{\circ}C$ in sintering temperature. 2) The optimum extraction conditions were $10%-H_2SO_4$ and 240 minutes in acid treating time. 3)Physical properties of sintering materials were confirmed as $\alpha-Al_2O_3$ by X-ray diffraction method and the purity of $\alpha-Al_2O_3$ was 99.23%.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.787-790
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• 2009

There are several types of compressors which are appropriate for hydrogen gas station. Metal diaphragm type of hydrogen compressor is the one of them, a use in which satisfies the requirements of maintaining gas purity and producing high pressure over 700 bar. The objective of this study is to investigate an characteristics of compression as bulk modulus of oil varies. Three cases of bulk modulus ranging from $2{\times}10^9$, $4.52{\times}10^9$ and $7{\times}10^9$ were studied through FSI (Fluid Structure Interaction) analysis. Gas pressure, oil pressure and deflection degree of diaphragm were analysed during a certain period of compression process. Highest pressure and deflection were found in the condition of high bulk modulus of $7{\times}10^9$.