• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.751-755
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• 2005

Carbon dioxide, included in the flue gas from the combustion of fossil fuel, was known as a representative green house gas and various removal and utilization technologies of it has been studied for the prevention of global warming. This study was performed as an effort to find out a method to reuse carbon dioxide separated from flue gas by magnetite powder. Magnetite powder was synthesized using various oxidizers and alkalinity controlled aqueous solutions of $FeSO_4{\cdot}7H_2O$ and NaOH at 50, 80, 90, $100^{\circ}C$ and analyzed by XRD and SEM. The analysis results showed that magnetite powder synthesized at higher alkalinity and temperature had crystalline spinel and cubic structure. The reduction by hydrogen and the oxidation by carbon dioxide of synthesized powder were studied by TGA. The results showed that magnetite powder synthesized at low alkalinity and temperature was non-cubical amorphous but crystalline and cubical at high alkalinity and temperature. Comparing magnetite powders synthesized using oxidants(air and oxygen) and nitrogen, magnetite powder using more oxygen containing oxidant synthesized more crystalline magnetite powder. The experimental results of redox reaction of the synthesized magnetite powder showed that the reduction by hydrogen and the oxidation by carbon dioxide were seldom observed below $400^{\circ}C$ and observed well at $500^{\circ}C$. Magnetite powder synthesized at $100^{\circ}C$ and alkalinity(molal concentration ratio of $FeSO_4{\cdot}7H_2O$ to NaOH) of 2.0 using $O_2$ showed the highest reduction of 27.15 wt％ and oxidation of 26.73 wt％, especially at reaction temperature of $500^{\circ}C$.

• The Journal of the Korea Contents Association
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• v.8 no.11
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• pp.210-216
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• 2008

In this study, image comparisons were carried out using a MRI contrast medium which was derived by mixing a polyaminocarboxylic ligand and a gadolinium (III) transition metal which is paramagnetic and has good neutron absorbing capabilities with Gd-DTPA which is currently being used widely in the clinical setting. By using a 1.0T (Harmony, SIEMENS) MR equipment, phantoms of which 100cc of saline was diluted with a diethylenetriaminetriacetic acid derivative and Gd-DTPA were imaged. The amount of diethylenetriaminetriacetic acid and Gd-DTPA which was diluted into the 100cc of saline was 0.05mmol/L, 0.1mmol/L, 0.15mmol/L, 0.2mmol/L, 0.3mmol/L, 0.5mmol/L, 1.0mmol/L, 2.0mmol/L, 3.0mmol/L and 4.9mmol/L respectively. Head coils were used and while fixing the SE pulse sequence and image variable (as TE is 14ms, 1NEX with a 256x201 matrix), the signal intensity and simple contrast ratios according to changing concentrations and TR were compared with various TR at 300ms, 400ms, 500ms, 600ms, 700ms, 800ms, 900ms, 1000ms, 1200ms, 1400ms and 1600ms. According to the comparison results of the signal intensity of the image based on changes in contrast medium concentrations and TR, the differences in signal intensity between the two contrast mediums were found to be small at $1.0{\sim}2.0mmol/L$ when the highest signal intensity was achieved. However, at concentrations of 1.0mmol/L or less, the signal intensity was markedly higher in the Diethylenetriaminetriacetic acid derivative than in the Gd-DTPA complex. It was also found that the differences in the signal intensities demonstrated by the concentrations of the contrast mediums were affected by the TR. Accordingly, the efficacy of the Diethylenetriaminetriacetic acid derivative was shown to be better than the Gd-DTPA and also possible to get the optimum image quality by the use of an appropriate TR with appropriate concentrations of contrast medium.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.3
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• pp.271-277
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• 2006

A mechanically pressed juice of Bokbunja (Rubus coreanus Miq.) extract was prepared using 70% ethanol solution. The extract was subjected to gamma-irradiation treatment (20 kGy) and investigated for its change of color and biological activities. Hunter $L^*$ values of the irradiated Bokbunja extract were increased in comparison with the non-irradiated extracts, and the $a^*\;and\;b^*$values decreased by the irradiation treatment. The content of the total phenolic compounds in the non-irradiated and irradiated extracts were 58.4 and 56.5 mg/g, respectively. The 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical scavenging activities of non-irradiated and irradiated extracts at a 250 ppm level were 80% and 79%, respectively. Lipid oxidation was retarded by addition of Bokbunja powder. Nitrite scavenging activity was the highest in the Bokbunja powder at pH 1.2 and the effect was not changed by irradiation. The Bokbunja powder showed antimicrobial activity against Salmonella Typhimurium and Bacillus cereus. However, irradiation of Bokbunja did not affect any physiological functions (p>0.05). A Salmonella mutagenicity assay indicated that the irradiated Bokbunja extract did not show any mutagenicity. Therefore, Bokbunja extract could be used in various applications as a functional material, such as ingredients of food and cosmetic, compositions with functions.

• Journal of the Korean Chemical Society
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• v.45 no.5
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• pp.461-469
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• 2001

The combinatorial approach has been applied to discover and optimize the composition of the novel or enhanced materials. In this study, we screened the optimum composition of the system SrO-Gd$_2$O$_3$-Al$_2$O$_3$ doped with $Tb^{3+}$ by a polymerized-complex combinatorial chemistry method. Mixtures with compositions of Sr, Gd and Al component that is in the range from 0 to 1 in about 0.05 increments could be tested. The sample powders were synthesized by a polymerized complex method. To prepare appropriately polymeric precursors, we used the metallic nitrates, citric acid and ethylene glycol. The luminescence properties of the synthesized powders are investigated using the UV and VUV (Vacuum-UV: 147 nm) photoluminescence spectrometer. In addition, the crystallinity and morphology of powder were monitored by X-ray diffraction spectrometer and scanning electron microscopy. In result of VUV PL works, there are good luminescent samples with the composition of 0.595 < x < 0.733 and 0.016 < y < 0.017 in Gd1-x-yAlxTbyO$\delta$ and 0.049 < x < 0.064 and 0.02 < y < 0.039 in $Sr_xAl_{1-x-y}Tb_yO_$\delta$$, their materials can be applicable to plasma display panels as the green phosphor.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.10a
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• pp.111-124
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• 2003

Processes that cause immobilization of contaminants in soil are of great environmental importance because they may lead to a considerable reduction in the bioavailability of contaminants and they may restrict their leaching into groundwater. Previous investigations demonstrated that pollutants can be bound to soil constituents by either chemical or physical interactions. From an environmental point of view, chemical interactions are preferred, because they frequently lead to the formation of strong covalent bonds that are difficult to disrupt by microbial activity or chemical treatments. Humic substances resulting from lignin decomposition appear to be the major binding ligands involved in the incorporation of contaminants into the soil matrix through stable chemical linkages. Chemical bonds may be formed through oxidative coupling reactions catalyzed either biologically by polyphenol oxidases and peroxidases, or abiotically by certain clays and metal oxides. These naturally occurring processes are believed to result in the detoxification of contaminants. While indigenous enzymes are usually not likely to provide satisfactory decontamination of polluted sites, amending soil with enzymes derived from specific microbial cultures or plant materials may enhance incorporation processes. The catalytic effect of enzymes was evaluated by determining the extent of contaminants binding to humic material, and - whenever possible - by structural analyses of the resulting complexes. Previous research on xenobiotic immobilization was mostly based on the application of $^{14}$ C-labeled contaminants and radiocounting. Several recent studies demonstrated, however, that the evaluation of binding can be better achieved by applying $^{13}$ C-, $^{15}$ N- or $^{19}$ F-labeled xenobiotics in combination with $^{13}$ C-, $^{15}$ N- or $^{19}$ F-NMR spectroscopy. The rationale behind the NMR approach was that any binding-related modification in the initial arrangement of the labeled atoms automatically induced changes in the position of the corresponding signals in the NMR spectra. The delocalization of the signals exhibited a high degree of specificity, indicating whether or not covalent binding had occurred and, if so, what type of covalent bond had been formed. The results obtained confirmed the view that binding of contaminants to soil organic matter has important environmental consequences. In particular, now it is more evident than ever that as a result of binding, (a) the amount of contaminants available to interact with the biota is reduced; (b) the complexed products are less toxic than their parent compounds; and (c) groundwater pollution is reduced because of restricted contaminant mobility.

• Korean Journal of Organic Agriculture
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• v.14 no.1
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• pp.55-67
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• 2006

A survey of 31 organic farmers were conducted to investigate the actual conditions of organic matter application. The amounts of organic matter application in the fields were higher in order of fruit, vegetable and rice farm. The average was 50 ton/ha in vegetable farms. In the green vegetable farms saw dust and animal manure were mainly utilized to make compost. Rice straw, wood chip, and forest bushes were also used for composting. In the fruit vegetable farms materials relatively lower in nitrogen content such as rice straw and cattle manure were used in vegetative period and materials higher in nitrogen content such as oil cake and wild grass were used in reproductive phase. Nutrient balance investigated in the farm in Icheon region who produce lettuce, angelica, and kale continuously in one cropping year indicated surplus in three major nutrients. Nitrogen and phosphorous were in excess by 29 and 10 kg respectively in the organic rice farm in yang-pyoung region. While soil chemical properties in the organic farms are within the adequate range in open field, it is much higher than the limits in the greenhouse soils. Overall application of organic matter is in an oversupply state. This results suggested that the organic matter management should be based on the soil conditions for sustainable cultivation. Chemical composition of organic matters and soil test reports should be considered prior to the application of organic matter.

• Journal of Animal Science and Technology
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• v.47 no.5
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• pp.867-876
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• 2005

The microbial contamination of ice cream product commercially available in Korea was determined using ice bar, ice cream, ice milk and non-milk fat ice cream. Irradiation effect on enhancement of microbiological safety was also investigated at doses of 1, 3, and 5 kGy. In all products, yeast and molds were not detected, however, total aerobic and coliform bacteria were detected at 1-2 and 1-1.5 Log CFU/g level, respectively. According to the different flavor used in ice cream, total aerobic bacteria were detected as 2.30, 2.90, and 3.32 Log CFU/g level in vanilla, chocolate, and strawberry ice cream, respectively. Yeast and mold was not detected in vanilla ice cream but 2.30 and 2.70 Log CFU/g in chocolate and strawberry ice cream, respectively. Coliforms were also detected 1-2 Log CFU/g in the ice cream with different flavors. Listeria inocua and Escherichia coli were detected from 3 commercial samples but Salmonella spp. was not detected using API kit. Gamma irradiation significantly reduced the level of the contaminated total aerobic bacteria, yeast and molds and coliform population in the ice creams. These results indicated that irradiation(5kGy or less) is effective to ensure safety of ice cream.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.110-120
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• 2005

For utilizing vitrification to treat low and intermediate level waste, industrial pilot plant was designed and constructed in October 1999 at Daejon, Korea through the joint research program among NETEC, MOBIS and SGN. More than 70 tests were performed on simulated IER, DAW etc. including key nuclide surrogate(Cs, Co); this plant has been shown to vitrify the target waste effectively and safely, however, some dust are generated from the HTF(High Temperature Filter) as a secondary waste. In case of long term operation, it is also concerned that pipe plugging can be occurred due to deposited dust in cooling pipe namely, connecting pipe between CCM(Cold Crucible Melter) and HTF. In this regard, we have developed the special complementary system of the off-gas treatment system to recycle the dust from HTF to CCM and to remove the interior dust of cooling pipe. Main concept of the dust recycling is to feed the dust to the CCM as a slurry state; this system is regarded as of an important position in the viewpoint of volume reduction, waste disposal cost and glass melt control in CCM. The role of DRS(Dust Recycling System) is to recycle the major glass components and key nuclides; this system is served to lower glass viscosity and increase waste solubility by recycling B, Na, Li components into glass melt and also to re-entrain and incorporate into glass melt like Cs, Co. Therefore dust recycling is helpful to control the molten glass; it is unnecessary to consider a separate dust treatment system like a cementation equipment. The effects of Dust Cleaner are to prevent the pipe plugging due to dust and to treat the deposited dust by raking the dust into CCM. During the pilot vitrification test, overall performance assessment was successfully performed; DRS and Dust Cleaner are found to be useful and effective for recycling the dust from HTF and also removing the dust in cooling pipe. The obtained operational data and operational experiences will be used as a basis of the commercial facility.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.151-156
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• 2002

Root zone cooling, such as soil or nutrient solution cooling, is less expensive than air cooling in the whole greenhouse and is effective in promoting root activity, improving water absorption rate, decreasing plant temperature, and reducing high temperature stress. The heat transfer of a soil cooling system in a plastic greenhouse was analyzed to estimate cooling loads. The thermal conductivity of soil, calculated by measured heat fluxes in the soil, showed the positive correlation with the soil water content. It ranged from 0.83 to 0.96 W.m$^{[-10]}$ .$^{\circ}C$$^{[-10]}$ at 19 to 36％ of soil water contents. As the indoor solar radiation increased, the temperature difference between soil surface and indoor air linearly increased. At 300 to 800 W.m$^{-2}$ of indoor solar radiations, the soil surface temperature rose from 3.5 to 7.$0^{\circ}C$ in bare ground and 1.0 to 2.5$^{\circ}C$ under the canopy. Cooling loads in the root zone soil were estimated with solar radiation, soil water content, and temperature difference between air and soil. At 300 to 600 W.m$^{-2}$ of indoor solar radiations and 20 to 40％ of soil water contents,46 to 59 W.m$^{-2}$ of soil cooling loads are required to maintain the temperature difference of 1$0^{\circ}C$ between indoor air and root zone soil.

• Journal of Life Science
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• v.28 no.5
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• pp.605-614
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• 2018

Bee pollen has an outer wall which is resistant to both acidic and basic solutions and even the digestive enzymes in the gastrointestinal tract. Therefore, the oral bioavailability of bee pollen is only 10-15%. A previous study reported on wet-grinding technology which increased the extraction of active ingredients from bee pollen by 11 times. This study was designed to investigate the safety of wet-ground bee pollen. First, a single dose of wet-ground bee pollen was tested in both rats and beagle dogs at dosages of 5, 10, and 20 g/kg and 1.5, 3, and 6 g/kg, respectively. In rats, compound-colored stools were found in those administered 10 g/kg or more of wet-ground bee pollen. In beagle dogs, 6 g/kg of wet-ground bee pollen induced diarrhea in one male for four hours. However, no obvious clinical signs were found through the end of the experiment in rats and beagle dogs. In addition, no histological abnormality was found in all animals. The data indicates that a single dose of up to 20 g/kg of wet-ground bee pollen is safe. Next, the genetic toxicity of nano-sized bee pollen was tested. This study employed a bacterial reverse mutation test, a micronucleus assay, and a chromosomal aberration assay. In the micronucleus assay, there was no genetic toxicity up to the dosage of 2 g/kg. There was also no genetic toxicity in the bacterial reverse mutation test and chromosomal aberration assay. This data provides important information in developing nano-sized bee pollen into more advanced functional foods and herbal medicines.