• Nuclear Engineering and Technology
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• v.41 no.3
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• pp.319-326
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• 2009

This study was carried out to investigate the high-acidity co-separation of Am and RE from a simulated radwaste solution by a solvent extraction using a mixture of Dimethyldibutyltetradecylmalonamide (DMDBTDMA, as an extractant) and dihexyl octanamide (DHOA, as a phase modifier) diluted with n-dodecane (NDD). All the experiments were conducted as a batch type. First, the environmentally friendly DMDBTDMA and DHOA composed of only CHON atoms were self-synthesized. Then, the conditions for the prevention of a third phase, generated in the organic phase were examined. In addition, the effects of the concentration of nitric acid, DHOA, oxalic acid and $H_2O_2$ on the co-extraction of Am and RE were elucidated. Consequently, the optimum condition of (0.5M DMDBTDMA+0.5M DHOA)/NDD-0.3M $C_2H_2O_4-4.5M$ $HNO_3$ and O/A=2 was obtained through experimental work. Under this condition, the extraction yields were found to be about 80% for Am, more than 70% for RE such as La, Eu, Nd, Ce, etc., 3% for Cs and Sr, 69% for Fe and less than 11% for Mo and Ru. For the co-extraction of Am and RE, Fe should be removed in advance or prevented from a co-extraction with Am by controlling the different extraction rates of Am and Fe. About 95% of the Am and RE in the organic phase were stripped using a 0.5M $HNO_3$.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.69-74
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• 2012

This study investigated the TNT decomposition by the treatment of alkaline hydrolysis. To obtain this objecitive, spectrum shift characteristics, pH effect, kinetics, and product analysis were examined during the alkaline hydrolysis by means of hydroxide ions. At pH = 12, an aqueous solution of TNT was changed into yellow-brown coloring, in which its absorbances were newly increased in a range of wavelength 400-600 nm. From the kinetic data, pseudo-first-order rate constant in a excess of hydroxide ion, in contrast to TNT concentration, was $0.0022min^{-1}$, which means that the reaction rate between TNT and hydroxide ion can be very slow, and that 1,047 min is necessary to achieve a 90% reduction of the initial TNT. In products analyses, nitrite ions and formic acid were mainly produced by the alkaline hydrolysis, nitrate ions and oxalic acid as minor products were generated.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.67-67
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• 2018

The 5xxx series aluminum alloys are recently used in not only marine system but also automotive area because of a low density material, good mechanical properties and better resistance to corrosion. However, Aluminum alloys are less resistant than the purest aluminum such as 1xxx aluminum alloy. Electrochemical anodization technique has attracted in the area of surface treatment because of a simple procedure, a low-cost efficiency than other techniques such as lithography and a large volume of productivity, and so on. Here, The relationship between the corrosion behavior and the thickness of aluminum anodic oxide have been studied. Prior to anodization, The 5052 aluminum sheets ($30{\times}20{\times}1mm$) were degreased by ultra-sonication in acetone and ethanol for 10 minutes and eletropolished in a mixture of perchloric acid and ethanol (1:4, volume ratio) under an applied potential of 20V for 60 seconds to obtain a regular surface. During anodization process, Aluminum alloy was used as a working electrode and a platinum was used as a counter electrode. The two electrodes were separated at a distance of 5cm. The applied voltage of anodization is conducted at 40V in a 0.3M oxalic acid solution at $0^{\circ}C$ with appropriate magnetic stirring. The surface morphology and the thickness of AAO films was observed with a Scanning Electron Microscopy (SEM). The corrosion behavior of all samples was evaluated by an open-circuit potential and potentio-dynamic polarization test in 3.5wt% NaCl solution. Thus, The corrosion resistance of 5052 aluminum alloy is improved by the formation of an anodized oxide film as function of increase anodization time which artificially develops on the metal surface. The detailed electrochemical behavior of aluminum 5052 alloy will be discussed in view of the surface structures modified by anodization conditions such as applied voltages, concentration of electrolyte, and temperature of electrolyte.

• Journal of Life Science
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• v.13 no.3
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• pp.365-373
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• 2003

Instead of deodorization appararus of fish oil, an adsorbent such as activated charcoal, activated alumina, silicagel, bamboo charcoal was packed in column alone or mixed with preparative ratio, and then test the effective deodorization with bleaching. In the progress of degumming, the effective method was 18 ml of 2.5% oxalic acid per 100m1 of crude large anchovy oil. The optical condition to deacidified was treating for 30 min at $40^{\circ}C$ with 2.5% sodium hydroride solution. The effective deodorization was added with 3% silicagel under the alone treating adsorbent, and mixed treating was 30% activated alumina and 10% silicagel but added to green tea powder was not effective. The major fatty acid of total lipid were 16:0, 20:5n-3, 18:1n-9, 16:1n-7 and 22:6n-3 after treatment of degumming, deacidfication and deodorizing in the large anchovy oil. The oxidative stability of refined anchovy oil added to $\alpha$-tocopherol was validated 20 days under the control, and 30 days in the case of $\alpha$-tocopherol. The 0.01% $\alpha$-tocopherol was more effective than 0.02% $\alpha$-tocopherol.

• Advances in environmental research
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• v.5 no.1
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• pp.19-35
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• 2016

The phytoextraction of some toxic heavy metals from municipal waste dump soil by castor plant (Ricinus communis) was tested under natural and single or mixed chelant-assisted scenarios in pot microcosms. A sandy loam with total metal contents (mg/kg): Cd (84.5), Cu (114.5), Ni (70.3), Pb (57.8), and Zn (117.5), was sampled from an active dumpsite in Calabar, Nigeria and used for the study. Castor (small seed variety) was grown under natural phytoextraction or single/binary chelant (citric acid, oxalic acid, and EDTA) applications (5-20 mmol/kg soil) for 63 days. Castor exhibited no visual phytotoxic symptoms with typically sigmoid growth profiles at the applied chelant doses. Growth rates, however, decelerated with increase in chelant dose. Post-harvest biomass yields were higher under chelant application than for natural phytoextraction. Both root and shoot metal concentrations (mg/kg) increased quasilinearly and significantly ($p{\leq}0.05$) with increase in chelant dose, furnishing maximum levels as: Cd (55.6 and 20.9), Cu (89.5 and 58.4), Ni (49.8 and 19.6), Pb (32.1 and 12.1), and Zn (99.5 and 46.6). Ranges of translocation factors, root and shoot bioaccumulation factors were 0.21-3.49, 0.01-0.89 and 0.01-0.51, respectively. Overall, the binary chelant treatments were less toxic for R. communis growth and enhanced metal accumulation in shoots to a greater extent than the single chelant scenarios, but more so when EDTA was present in the binary combination. This suggests that the mixed chelants could be considered as alternative treatments for enhanced phytoextraction and revegetation of degraded waste dump soils.

• Applied Biological Chemistry
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• v.4
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• pp.33-42
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• 1963

1. Two fermentation methods have been compared for the production of Takju (Korean native Sake). One method (S1) uses 'Nuruk' (Korean mold wheat) and the other method (S2) uses 'Nuruk' and mold rice. The chemical analysis of source material, also, have been made in order the check the quantitative changes during the fermentation. The results are summarized below: a. The rate of fermentation was slower for the S2 method than for the S1 method. However, the residual sugar in the S2 method was smaller and the amount of alcohol produced the same as with the S1 method. This was true in spite of the fact that the total initial sugar content for the S2 method was 10 percent below that of S1. b. With both the S1 and S2 methods, 80 percent of the total alcohol production was obtained with in 3 to 4 days. c. The pH value of the base material at the beginning of fermentation was markedly different between the two methods I.e.6.0 to 6.2 for S1 and 4.8 to 5.2 for S2. However, after one or two day the pH of both materials was about the same 4.0 to 4.2 and remained at this value unit the fermentation was complete. 2. Organic acids and Sugars in the source materials have been detected by the paper partition chromatography(p.p.c.) method and the followings are obtained. a. Important Organic acids are Fumalic, malic Succinic, Citric, Acetic aicds in polished rice and Fumalic, Succinic, Acetic, Citric, Malic and Oxalic acids 'Nuruk'. The same kinds of acids as in the rice are found in mold rice, However, amount of Citrice acid is markedly increased in mold rice. b. The important Sugar, Glucose, Fructose and Raffinose in polished rice, Gulcose, Fructo, se, Xylose and one which supposed to be Kojibjose in 'Nuruk'. Glucose and those supposed to be Isomaltose, Kojibiose and Sakebiose and found in rice mold, however, no Sucrose, which was exist in polished rice, was found. 3. The important Organic acids found in fermenting mash using the p.p.c. method were Lactic, Succinic and Acetic. Citric acid identified early in the fermentation, S2 method. remained throughout. However, with the S1 method Cirtic acid was detected only during the late stage of fermentation. Sugars not found in the original materials were two which supposed to be Isomaltotriose and Pentose. Maltose found at the beginning of the fermentation disappeared within one day, Isomaltose was detected throughout the period of fermentation. 4. The Somogyi method which was employed to determine the quantitative changes of sugars in the orginal meterial and mach, showed that polished rice containes in order and in largest amounts Sucrose, Glucose, Raffinose and Fructose. 'Nuruk' contained almost equal quantities of Glucose and Fructose. However, the Glucose content of the mold rice exceeded that originally in the polished rice by 25 or 30 times. Only a small quantity of free sugars was found in the mash at the end of the fermentation.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.69-76
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• 2012

This study focuses both on the quantitative measurement of hydroxyl radicals formed by an electron beam (E-beam) process and on the decomposition of pentachlorophenol(PCP) in the presence of $H_2O_2$ and $Fe^{3+}-EDTA$ as additives. To attain this objective, the quantitative measurement of hydroxyl radical was performed with the hydroylation of benzoic acid (BA), producing hydroxybenzoic acid (OHBA). As a result, the concentrations of hydroxyl radical measured were lower than those of hydroxyl radical predicted. Probably, it indicates that the reactive species generated during E-beam irradiation are able to scavenge the hydroxyl radicals. In particular, the degradation of PCP was promoted by the addition of $H_2O_2$ (< 1mM). On the other hand, its degradation as well as the generation of chloride ions as a by-product was inhibited by the addition of $H_2O_2$ (> 1mM), and thus carbon yield(%) of oxalic acid as a by-product was increased. During E-beam irradiation the addition of $Fe^{3+}-EDTA$ effectively decomposed the PCP, thus increasing the G-values. Considering the formation of OHBA and the decomposition of PCP, these results suggest that the addition of $Fe^{3+}-EDTA$ in the E-beam process can produce the further hydroxyl radicals and enhance the efficiency of PCP decomposition at low dose.

• Clean Technology
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• v.26 no.2
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• pp.116-121
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• 2020

In this paper, the recycling of waste Ni-MH battery by-products for electric vehicle is studied. Although rare earths elements still exist in waste Ni-MH battery by-products, they are not valuable as materials in the form of by-products (such as an insoluble substance). This study investigates the recovering of rare earth oxide for solvent extraction A/O ratio, substitution reaction, and reaction temperature, and scrubbing of the rare earth elements for high purity separation. The by-product (in the form of rare earth elements insoluble powder) is converted into hydroxide form using 30% sodium hydroxide solution. The remaining impurities are purified using the difference in solubility of oxalic acid. Subsequently, Yttrium is isolated by means of D2EHPA (Di-[2-ethylhexyl] phosphoric acid). After cerium is separated using potassium permanganate, lanthanum and neodymium are separated using PC88A (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) and it is calcinated at a temperature of 800 ℃. As a result of the physical and chemical measurement of the calcined lanthanum and neodymium powder, it is confirmed that the powder is a microsized porous powder in an oxide form of 99.9% or more. Rare earth oxides are recovered from Ni-MH battery by-products through two solvent extraction processes and one oxidation process. This study has regenerated lanthanum and neodymium oxide as a useful material.

• Food Science and Preservation
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• v.23 no.4
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• pp.479-487
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• 2016

This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP) and ethylene-absorbent on the qualities of Prunus mume fruit. Prunus mume fruits were stored without film packaging (Cont), packed in LDPE film (Cont-P), and packed with ethylene-absorbent (Cont-PE). Fruits were treated with 1-MCP (1 ppm) for 24 hr at $1^{\circ}C$. After treatment, fruits were packed in LDPE film (MCP-P) and with ethylene-absorbent (MCP-PE) and then stored at $1^{\circ}C$ for 8 weeks. Total soluble solids increased during storage but decreased after 6 weeks while total acidity decreased during storage. Cont was almost completely decayed after 8 weeks of storage while Cont-P, Cont-PE, MCP-PE, and MCP-P were 46, 69, 83, and 5% decayed, respectively. L value decreased but a value increased during storage in all samples. Firmness of peel and flesh of samples decreased gradually for 8 weeks. Respiration rate did not show any significant difference among samples. Ethylene production of Cont showed $0.05{\mu}L/kg/h$ but immediately after 1-MCP treatment, it showed $0.02{\mu}L/kg/h$. Oxalic and malic acids decreased while citric acid increased during storage; fructose and glucose substantially decreased after 8 weeks whereas sorbitol and sucrose increased upto 4 weeks and then decreased thereafter. Based on these results, packing the fruits treated with 1-MCP could extend the freshness of Prunus mume fruit.

• Journal of the Korean Society of Food Culture
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• v.2 no.1
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• pp.25-31
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• 1987

We have examined to evaluate the taste compounds of damchi-jeotguk(concentrated sea mussel extract) which is a kind of traditional processed sea food in Korea. The contents of such compounds as free amino acids, nucleotides their and related compounds, non-volatile organic acid and fatty acid composition were analyzed. The content of total free amino acids was 10520.5mg/100g on dry basis and the major ones were glycine, arginine, aspartic acid and glutamic acid. These amino acids were resulted as 55.7% of total free amino acids in damchi-jeotguk. Hypoxanthine was the highest content($8.77\;{\mu}mole/g$, dry basis) of nucleotides and their related compounds. Free amino acid-N was the most abundant, resulting 53.3% of extractive nitrogen which was 3490.2mg/100g on dry basis and next ammonia-N, nucleotide-N and TMAO-N in order. The major non-volatile organic in damchi-jeotguk were succinic acid(125.5mg/100g, dry basis) and lactic acid 91.9mg/100g, dry basis). In this fatty acid composition of total lipid, polyenoic acid was abundant holding 45.5%. The major fatty acids were 16 : 0, 18 : 2, 22 : 6, 18 : 1 and 20 : 5. It was concluded from the omission test and chemical analysis that the major taste compounds of damchi-jeotguk were free amino acids and non-volatile organic acids.