• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.85-96
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• 2021

Radioactive mixed waste (RMW) means waste mixed with radioactive substances and hazardous substances. In Korea, there are definitions and disposal restrictions on RMW in the Nuclear Safety Management Act, but it is difficult to apply because the contents are insufficient, so this paper proposed applicable management standards. The main RMW generated from nuclear power plants is waste oil, waste asbestos, PCB, and waste fluorescent liquid, and their radiation characteristics are mostly at very low levels and some are estimated at low levels. In addition to nuclear power plants, RMW also occurs in research institutes, industries, and hospitals. The acceptance criteria of all disposal facilities in the world basically prohibit disposal of RMW unless the hazardous substances of RMW are removed or mitigated below the standard value. Cases in Korea, the United States, Japan and Europe were reviewed to propose the RMW management standards in Korea. With reference to the results of the above review, this paper clearly defined RMW and proposed detailed management standards for the separation, storage, treatment and disposal of hazardous substances by applying the Waste Control Act. It also mentioned legislation of management standards, regulatory methods, and acceptance criteria of disposal facility operator.

• Journal of Life Science
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• v.33 no.8
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• pp.680-691
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• 2023

Peak oil, climate change, and microplastics caused by the production and usage of petroleum-based plastics have threatened the sustainability of our daily life, and this has emerged as a recent global issue. To solve this global issue, the production and usage of biodegradable eco-friendly bioplastics such as polyhydroxyalkanoates (PHAs) has been suggested as an alternative. Therefore, in this review, the present status of global PHA manufacturers, the advantages of the production of PHAs using marine-origin microorganisms (with their productivity potential) and further required research and development strategies for cost-competitive production of PHAs using marine-based microorganisms were investigated. In this review, PHAs produced from marine microorganisms were found to have similar physical properties to petroleum-based plastics but with several advantages that can reduce the costs of PHA production. Those advantages include, seawater used in the medium preparation step, and osmotic-based cell lysis technology used in the separation and purification steps. However, the PHA productivities from marine microorganisms showed somewhat lower efficiencies than those from the commercial strains isolated from terrestrial environments. In order to solve the problem, further research strategies using synthetic microbiology-based technology, the development of long-term continuous culture technology, and solutions to improve PHA efficiency are required to meet future market demands for alternative bioplastics.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.231-237
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• 2009

This paper aimed to develop a solvent extraction and purification process to recover high-purified ${\beta}$-carotene from recombinant Escherichia coli. Cells harvested from the culture broth were treated through numerous steps: dehydration, solvent extraction, crystal formation and separation. To optimize the extracting condition, experiments were carried out to investigate the effect of cell disruption, temperature, organic solvents, solvent-biomass ratio on the yield of ${\beta}$-carotene extracted from cells. The result indicated that no significant differences of extraction yield were observed from cells with or without step of cell disruption. Among different extracting solvents, the highest extraction yield of ${\beta}$-carotene, 30.3 mg-${\beta}$-carotene/g-dry cells, was obtained with isobutyl acetate at solvent-biomass ratio 25 mL/g-dry cells at $50^{\circ}C$. Notably, in case of acetone, the extraction yield was quite low when using acetone itself, but increased almost up to the highest value when combining this solvent and olive oil. The purity of ${\beta}$-carotene crystals obtained from crystallization and separation was 89%. The purity degree was further improved up to 98.5% by treating crude crystals with additional ethanol washing.

• Journal of Environmental Impact Assessment
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• v.29 no.3
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• pp.157-181
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• 2020

Sediments from rivers, lakes and marine ports serve as end points for pollutants discharged into the water, and at the same time serve as sources of pollutants that are continuously released into the water. Until now, the contaminated sediments have been landfilled or dumped at sea. Landfilling, however, was expensive and dumping at sea was completely banned due to the London Convention. Therefore, this study applied contaminated sedimentation soil of 'Royal Palace Livestock Complex' as soil purification method. Soil remediation methods were applied to pretreatment, composting, soil washing, electrokinetics, and thermal desorption by selecting overseas application cases and domestically applicable application technologies. As a result of surveying the site for pollutant characteristics, Disolved Oxigen (DO), Suspended Solid (SS), Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) exceeded the discharged water quality standard, and especially SS, COD, TN, and TP exceeded the standard several tens to several hundred times. Soil showed high concentrations of copper and zinc, which promote the growth of pig feed, and cadmium exceeded 1 standard of Soil Environment Conservation Act. In the pretreatment technology, hydrocyclone was used for particle size separation, and the fine soil was separated by more than 80%. Composting was performed on organic and Total Petroleum Hydrocarbon (TPH) contaminated soils. TPH was treated within the standard of concern, and E. coli was analyzed to be high in organic matter, and the fertilizer specification was satisfied by applying the optimum composting conditions at 70℃, but the organic matter content was lower than the fertilizer specification. As a result of continuous washing test, Cd has 5 levels of residual material in fine soil. Cu and Zn were mostly composed of ion exchange properties (stage 1), carbonates (stage 2), and iron / manganese oxides (stage 3), which facilitate easy separation of contamination. As a result of applying acid dissolution and multi-stage washing step by step, hydrochloric acid, 1.0M, 1: 3, 200rpm, 60min was analyzed as the optimal washing factor. Most of the contaminated sediments were found to satisfy the Soil Environmental Conservation Act's standards. Therefore, as a result of the applicability test of this study, soil with high heavy metal contamination was used as aggregate by applying soil cleaning after pre-treatment. It was possible to verify that it was efficient to use organic and oil-contaminated soil as compost Maturity after exterminating contaminants and E. coli by applying composting.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.842-853
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• 2014

For developing indigestible lipids, symmetric triacylglycerol (ST) and asymmetric triacylglycerol (AT) were produced by enzymatic interesterification using high oleic sunflower oil, palmitic ethyl ester, and stearic ethyl ester in a shaking water bath. Used enzymes were Lipozyme RMIM for ST and Lipozyme TLIM for AT. To remove ethyl ester from reactants, methanol fractionation (reactant : methanol=1:5, w/v, $25^{\circ}C$) and florisil separation (reactant : florisil=1:8, w/w) were applied. Acetone fractionation (reactant : acetone=1:9, w/v) was implemented to separate triacylglcerol (TAG) species into ST and AT. Fractions I (before fractionation), II (after fractionation, liquid phase) and III (after fractionation, solid phase) were separated from ST, whereas fractions IV (after 1st fractionation, liquid phase) and V (after 2nd fractionation, solid phase) were from AT. From sn-2 fatty acid composition analysis, the sum of palmitic acid (C16:0) and stearic acid (C18:0) was 4.9~6.5 area% in ST (I, II, III), and 41.9~43.9 area% in AT (IV, V). In vitro digestion was performed for 0, 15, 30, 60, and 120 minutes at $37^{\circ}C$ in a shaking water bath. For the digestion results, hydrolysis of V was only 40% compared to others (I, II, III, IV) at 120 minutes due to its melting point ($49^{\circ}C$). However, initially (15 minutes), hydrolysis (%) was as follows: V$32.5^{\circ}C$, $31.8^{\circ}C$) and different slip melting points ($31.3^{\circ}C$, $19.5^{\circ}C$). Even though IV has a lower TAG content composed of two saturated fatty acids than III, it had a similar melting point.

• KSBB Journal
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• v.23 no.1
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• pp.1-7
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• 2008

The world demand of ethanol as an alternative fuel for gasoline is increasing rapidly because of high oil price and global climate change. Most of ethanol is currently produced from corn grain or sugars in sugarcane and sugar beet. Because these sources compete with foods and animal feed and are not expected to be enough for future demand of ethanol. Thus, cellulosic ethanol from agricultural residues or wood has to be commercialized in near future. Typical cellulosic ethanol production consists of pretreatment, enzyme hydrolysis, fermentation and product separation. This paper reviews the principles and status of each step and discusses issues for cellulosic ethanol production.

• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.179-184
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• 1998

As a way of mass process of onion, Allium cepa L., the oleoresin decompressed and concentrated is an alternative process to minimize lowering in the quality of onion during storage, to improve the original flavor and taste, and to increase variety as processing aids. This study was performed to investigate on the quality stability during storage of oleoresin. Oleoresin product was manufactured by mixing a concentration of onion juice and ethanol extract homogenously, emulsified by an additional 2% PGDR(polyglycerol condensed ricinoleate) and 1% cysteine. During 60 days storage at 5$^{\circ}C$, $25^{\circ}C$ and 4$0^{\circ}C$ the total sugar content in oleoresin product was very stable, and absorbances at 420nm as browning reaction index were 0.38, 1.53 and 3.32, respectively, addition of 1% cysteine retarded the browning reaction effectively. When oleoresin product was centrifuged(2000$\times$G, 60 minutes), the volumes of emulsion level without separation were 96.8%, 94.1% and 9.06%, respectively during 20 days, 40 days and 60 days storage at 5$^{\circ}C$, and those during 60 days storage at $25^{\circ}C$ and 4$0^{\circ}C$ were appeared to be 83.2% and 75.4%. Showing lower level as increasing storage temperature. Antioxidant indexes(AI) of soybean oil added 1% oleoresin without storage and 0.02% BHA were 1.39 and 1.72. The former showed 80.8% antioxidant activity on induction time extension effect of the latter. Antioxidant indexes of oleoresin decreased slightly as increasing storage temperature and were 1.37, 1.30 and 1.08. Total pyruvate contents were 89.9%, 79.7% and 65.2%, respectively during 60 days storage at 5$^{\circ}C$, $25^{\circ}C$ and 4$0^{\circ}C$. Rate constant, Q10 value and activation energy were 1.381~4.735 mmol/$\ell$.hr, 1.537~1.694 and 11.649 ㎉/g mole for the reduction of pyruvates in the range of storage temperatures during oleoresin storage.