• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.357-363
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• 2015

The development of the environment-friendly tire that meets the standard requirements according to tire labeling system can be improved through using highly homogeneous silica immobilized zinc oxide nanoparticles. In this study, a considerable amount of nanoporous silica was essentially added into nano zinc oxide to improve the physiochemical properties of the formed composite. The introduction of nanoporous silica materials in the composite facilitates the improvement of the wear-resistance and increases the elasticity of the tread. Therefore, the introduction of nanoporous silica can replace carbon black as filler in the formation of composites with desirable properties for conventional green tire. Herein, mesoporous silica immobilized zinc oxide nanoparticle with desirable properties for rubber compounds was investigated. Composites with homogeneous dispersion were obtained in the absence of dispersants. The dispersion stability was controlled through varying the molar ratio, ageing time and mixing order of the reactants. A superior dispersion was achieved in the sample obtained using 0.03 mol of zinc precursor as it had the smallest grain size (50.5 nm) and then immobilized in silica aged for 10 days. Moreover, the specific surface area of this sample was the highest ($649m^2/g$).

• Journal of the Korean Chemical Society
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• v.54 no.2
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• pp.192-197
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• 2010

The spinel compound was obtained by the thermal decomposition of Zn-Co and Zn-Ni gel prepared by sol-gel method using oxalic acid as a chelating agent. The formation of spinel compound has been comfirmed by thermogravimetric analysis (TGA), x-ray powder diffraction (XRD) and infrared spectroscopy (IR). The particle size of 13 nm~16 nm was calculated by Scherrer's equation. The sol-gel method provides a practicable and effective route for the synthesis of the spinel compound at low temperature ($350^{\circ}C$). The kinetic parameters such as activation energy (Ea) and pre-exponential factor (A) for each compound were found by means of the Kissinger method and Arrhenius equation. The decomposition of spinel compound has an activation energy about 155 kJ/mol. Finally, the thermodynamic parameters (${\Delta}G^{\varphi}$, ${\Delta}H^{\varphi}$, ${\Delta}S^{\varphi}$) for decomposition of spinel compound was determined.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.223-228
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• 2021

The final disposal method for asbestos building materials is to be landfilled at a designated waste landfill in accordance with the Waste Management Act. However, it is difficult to secure a domestic designated waste landfill site to landfill the entire amount of asbestos waste, which is expected to emit more than 400,000 ton/year by 2044. In this study, a detoxification treatment was performed on a ceiling tex with a density of 1.0 to 1.2g/cm³ containing 3 to 7% of chrysotile, and it was used as a reinforcing fiber for extruded panels. It was confirmed that asbestos components were detoxified through the reaction process using 30% oxalic acid and carbon dioxide, and it was recognized that these detoxifying properties were maintained even after extrusion molding. However, it was found that milling to a fiber size of less than 1mm for complete detoxification of asbestos resulted in a decrease in reinforcing performance. Therefore, in the case of using detoxified asbestos fibers in the extrusion molding process, it is considered desirable to add fibers with a length of 5mm or more to improve the reinforcing performance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.s01
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• pp.86-97
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• 1988

Sesame(Sesamum indicum L.) is probably the most ancient oilseed crop known in the world. The seed of sesame is used in a variety of ways as food. The whole seed may be eaten raw, either roasted or parched, or fed to birds and stock. Sesame oil is used as a salad or cooking oil, in shortening, margarine and in the manufacture of soap. Minor uses are as a fixative in the perfume industry and formerly as a carrier for fatsoluble substances in pharmaceuticals such as penicillin. One of the minor constituents of sesame oil, sesamin, is used for its synergistic effect in pyrethrin insecticides, in addition of a small quantity of this substance markedly increases the effectiveness of fly sprays. The meal remaining after oil extraction can be used as and animal feed-stuff or as manure. In general sesame meal is considered to be equal to cottonseed or soybean meal as a protein supplement for livestock and poultry. It is especially high in certain amino-acids such as methionine, which is low in soybean meal, and thus can be combined with it or similar meal to form a more balanced ration. An attempt to summarize the literature review on quality improvement of sesame was made to discuss the accomplishments of the past and perspectives in the future. The reviews on quality improvement of sesame were mainly discussed in connection with the cultural practices and genetic informations in current status. The emphasis focussed on environmental variation of quality in cultural practices, such as harvest time, variety by location, climatic condition, fertilizer application, and growth regulator treatment. On the genetic variation of quality, it was discussed on variety background, mutation breeding, correlations, and inheritance of quality related characteristics. It also was discussed on relationship between quality and plant traits, storage condition or period, and seed coat color. Moreover, current research status were reviewed on some minor elements such as sesamin, oxalic acid, and trypsin inhibitor. As a results of the review, the lack of an effort to quality improvement in each utilization area was indicated as a problem area. More active efforts for the improvement of quality were also insufficient to incorporate the available genes for quality in breeding method or collection and analysis of breeding materials. Therefore, researches in the future would be recommended to emphasize on these problem areas.

• Food Science and Preservation
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• v.30 no.5
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• pp.833-846
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• 2023

Onions are essential vegetables for Koreans' diet and have various physiological activities. However, problems arise every year due to the imbalance between production and demand. Therefore, in this study, nutritional and functional components, and antioxidant activity were analyzed for each growth period in order to utilize onions at the disposal period. Whole onions harvested before June showed higher values of general ingredients, inorganic ingredients, organic acids, spiraeoside, quercetin, total chlorophyll, and antioxidant activity than bulbs harvested in June. On the other hand, the free sugar content was higher in the bulb of the harvest season in June than in whole onions. The total thiosulfinate content was similar to that of whole onions and bulbs in the early stages of growth. In addition, as a result of comparing the flavonoid compound and antioxidant activity of each onion variety, whole onions harvested at 25 weeks were higher in content than onion bulbs harvested in June. In conclusion, onions before the harvest season in June had excellent utilization value as food. Harvesting before 21 weeks is desirable for growing onions with excellent nutritional value, while harvesting after 23 weeks is recommended for excellent functional components and antioxidant activity in onions.

• Journal of the Korean Electrochemical Society
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• v.17 no.2
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• pp.111-118
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• 2014

The electrochemical properties using the cells assembled with the synthesized $LiCoO_2$(LCO) were evaluated in this study. The LCO was synthesized from high-purity cobalt sulfate($CoSO_4$) which is recovered from the cathode scrap in the wastes lithium ion secondary battery(LIB). The leaching process for dissolving the metallic elements from the LCO scrap was controlled by the quantities of the sulfuric acid and hydrogen peroxide. The metal precipitation to remove the impurities was controlled by the pH value using the caustic soda. And also, D2EHPA and $CYANEX^{(R)}272$ were used in the solvent extraction process in order to remove the impurities again. The high-purity $CoSO_4$ solution was recovered by the processes mentioned above. We made the 6 wt.% $CoSO_4$ solution mixed with distilled water. And the 6 wt.% $CoSO_4$ solution was mixed with oxalic acid by the stirring method and dried in oven. $LiCoO_2$ as a cathode material for LIB was formed by the calcination after the drying and synthesis with the $Li_2CO_3$ powder. We assembled the cells using the $LiCoO_2$ powders and evaluated the electrochemical properties. And then, we confirmed possibility of the recyclability about the cathode materials for LIBs.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.69-74
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• 2010

Black garlic has recently received significant attention due to its various health functional properties, and there has been an increase in demand for its use as a functional food. This study was performed to determine the optimum concentration for the fermentation of black garlic yakju. In addition, the antioxidant activity of the fermented black garlic yakju was examined. The alcohol content in the black garlic yakju significantly increased for 6 days and the pH gradually increased as the concentration of black garlic increased. The reducing sugar content at each black garlic concentration was maximal when it was fermented for 24 hours, and then rapidly decreased at longer fermentation periods. The main organic acids were lactic, citric, malic and oxalic acid. Also, the lactic acid content increased as the concentration of the black garlic increased where as the content of other organic acids decreased. The total polyphenol content, ferric ion reducing antioxidant power (FRAP) activity and DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical scavenging activity of black garlic yakju increased as the concentration of black garlic increased. The sensory characteristics of fermented black garlic yakju were evaluated in terms of color, flavor, taste and overall acceptability, and the highest overall acceptability value was obtained for yakju containing a black garlic concentration of 1-3%. Therefore, the optimum concentration of black garlic was determined to be 1% for the production of high quality black garlic yakju.

• Tuberculosis and Respiratory Diseases
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• v.55 no.5
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• pp.516-521
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• 2003

The Aspergillus species produces metabolic products that play a significant role in the destructive processes in the lung. We experienced a case of chronic necrotizing pulmonary aspergillosis caused by an Aspergillus niger infection, which contained numerous calcium oxalate crystals in the necrotic lung tissue. A 46-year-old man, who had a history of pulmonary tuberculosis, presented with high fever, intermittent hemoptysis and pulmonary infiltrations with a cavity indicated by the chest radiograph. Despite being treated with several antibiotics and anti-tuberculosis regimens, the high fever continued. The sputum cultures yielded A. niger repeatedly, and intravenous amphotericin B was then introduced. The pathological specimen obtained by a transbronchial lung biopsy revealed numerous calcium oxalate crystals in a background of acute inflammatory exudates with no identification of the organism. Intravenous amphotericin B was continued at a total dose of 1600 mg, and at that time he was afebrile, although the intermittent hemoptysis continued. On the $63^{rd}$ hospital day, a massive hemoptysis (about 800 mL) developed, which could not be controlled despite embolizing the left bronchial artery. He died of respiratory failure the next day. It is believed that the oxalic acid produced by A. niger was the main cause of the patient's pulmonary injury and the ensuing massive hemoptysis.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.454-459
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• 2009

In order to identify the effect of soil salinity on saturated hydraulic conductivity in reclaimed paddy soils, we established the soil columns uniformly packed with soils collected at every 20 cm up to 60 cm from the reclaimed paddy area with high and low salinity which has been cultivated rice plants for the last 30 years. The soil textures were sandy loam and loamy sand for high-salinity and low-salinity topsoils, respectively. For high-salinity and low-salinity soils the ECes were ranged from 25.2 to $37.8dS\;m^{-1}$ and 3.0 to $3.4dS\;m^{-1}$ while the ESPs were ranged from 7.70 to 20.84 % and from 5.12 to 11.33 %, respectively. The bulk densities of the soil columns were adjusted to $1.15{\pm}0.03g\;cm^{-3}$. The results of the soil column experiments shows that the stabilized saturated hydraulic conductivity of low-salinity soil was $0.62cm\;hr^{-1}$ at the topsoil while there were little water flow at the bottom of the soil columns packed with high-salinity soils. After removal of $Na^+$ ions with $1N\;NH_4OAc$ from the high-salinity soil, Ksat of the saline soil was drastically increased to $0.23cm\;hr^{-1}$. Soil columns of high-salinity topsoil treated with four different concentration of NaCl influent after removal of soluble and exchangeable cations with $1N\;NH_4OAc$ show Ksat in the range of $0.1{\sim}0.15cm\;hr^{-1}$ and the Ksat slightly decreased as the concentration of NaCl influent was increasing. Conclusively, we could assume that $Na^+$ can be significantly contributed to the saturated hydraulic conductivity in newly reclaimed sandy soil.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.4
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• pp.120-129
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• 2003

The anodic alumina is synthesized using 0.3M oxalic acid and the barrier layers of the anodic alumina are removed using the 20wt% $H_2SO_4$ solution. The structure of the anodic alumina is analyzed by XRD and SEM. It is observed by SEM that the size of anodic alumina pore is about 60nm. And the uniformity of the anodic alumina surface under the 20wt% $H_2SO_4$ solution is poorer than the unifomity of the the normal anodic alumina surface. The anodic alumina and the carbon are used cathode and anode in$Cd(NO_3)_2{\cdot}4H_2O$, $Co(NO_3)_2{\cdot}6H_2O$ and $PbSO_4$ solutions. In this study, the constant D.C. electrical current is flowed in each solution for 24hours. It is found that the voltages so far as 4.6, 3.4 and 5.1V at $Cd(NO_3)_2{\cdot}4H_2O$, $Co(NO_3)_2{\cdot}6H_2O$ and $PbSO_4$ solutions increase with increasing the flowing current time and after the voltage does not change which values are 4.2, 2.7 and 2.4V, respectively. The amount of metal ions in solutions decrease with increasing the flowing current time until the flowing current time is 18hours and the metals are formed at the surface of anodic alumina. After the metal ions are removed using the anodic alumina, and $Cd^{2+}$, $Co^{2+}$ and $Pb^{2+}$ ions are removed again using flow cell with retriculate vitreous carbon(RVC) working electrode. The concentration of $Cd^{2+}$, and $Co^{2+}$ions decrease until the flowing time of the solutions is 20minutes and the concentration of $Pb^{2+}$ ion decreases until that time is 30minutes. In this case, the removal effects of $Cd^{2+}$, $Co^{2+}$ and $Pb^{2+}$ ions are 34.78, 28.79 and 86.38%, respectively. And it is possible that both $Cd^{2+}$ and $Co^{2+}$ions are adsorbed in pore of RVC at the same time and the removal effects of $Cd^{2+}$ and $Co^{2+}$ions are 32.30 and 31.37%.