• Resources Recycling
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• v.31 no.4
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• pp.40-48
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• 2022

In waste lithium iron phosphate (LFP) batteries, the cathode material contains approximately 4% lithium. Recycling the constituent elements of batteries is important for resource circulation and for mitigating the environmental pollution. Li contained in the waste LFP cathode powder was selectively leached using persulfate-based oxidizing agents, such as sodium persulfate, potassium persulfate, and ammonium persulfate. Leaching efficiency and waste LFP powder properties were compared and analyzed. Pulp density was used as a variable during leaching, which was performed for 3 h under each condition. The leaching efficiency was calculated using the inductively coupled plasma (ICP) analysis of the leachate. All types of persulfate-based oxidizing agents used in this study showed a Li leaching efficiency over 92%. In particular, when leaching was performed using (NH₄)₂S₂O₈, the highest Li leaching percentage of 93.3% was observed, under the conditions of 50 g/L pulp density and an oxidizing agent concentration of 1.1 molar ratio.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.179-187
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• 2022

In this study, the synthesis of 1,2-dodecylaminopropanediol (1,2-DDAP) having a 12 carbon chain length and an amine group was designed to improve the preservation and hydrophilicity of 1,2-alkanediol-based compounds. 1,2-DDAP was prepared by reacting dodecylamine (DDA) with 3-monochloro-1,2-propanediol (3-MCPD) in an ethanol solvent at 40 ℃, and its yield and purity were about 56% and 98%, respectively, under a reaction condition of 2 h and a DDA:3-MCPD molar ratio of 1:0.8. The antimicrobial effect of 1,2-DDAP showed the values of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against microorganisms at concentrations of 10 to 100 times lower than those of 1,2-octanediol(1,2-ODIOL) or 1,2-decanediol (1,2-DDIOL). Based on the hydrophilic properties of 1,2-DDAP, mixed preservatives were prepared by adding small amounts of 1,2-ODIOL or 1,2-DDIOL, which are poorly soluble in water, with 1,2-DDAP. Mixed preservatives exhibited an effect of inhibiting microorganisms equal to or greater than that of 1,2-DDAP alone in antimicrobial activity tests. As a result of confirming the preservation effect in lotion (cosmetic formulation) for application, 1,2-DDAP showed similar antimicrobial activity at concentrations of 0.3 to 0.6 times lower than that of 1,2-ODIOL or 1,2-DDIOL. Therefore, it is considered that the use of 1,2-DDAP alone and the mixed use with small amounts of 1,2-ODIOL or 1,2-DDIOL can be a good alternative to preservatives in the product.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.620-629
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• 2022

By varying various experimental conditions such as heating rate, molar hourly space velocity (MHSV), and nitridation reaction temperature, vanadium oxynitride was prepared through temperature programmed reduction/nitridation reaction (TPRN) of vanadium pentoxide and ammonia, and characterization were performed. In order to investigate the physico-chemical properties of the prepared catalyst, N₂ adsorption-desorption analysis, X-ray diffraction analysis (XRD), hydrogen temperature programmed reduction (H₂-TPR), temperature programmed oxidation (TPO), ammonia temperature programmed desorption (NH₃-TPD), transmission electron microscopy (TEM) was performed. Transformation of V₂O₅ with 5 m² g^-1 low specific surface area by reduction at 340 ℃ to V₂O₃ showed a high specific surface area value of 115 m² g^-1 by micropore formation. As the nitridation temperature increased beyond that, the specific surface area continued to decrease due to sintering. The nitridation reaction variable that had the greatest influence on the specific surface area was the reaction temperature, and the x + y value of VN_xO_y of a single phase approached from 1.5 to 1.0 as the nitridation reaction temperature increased. At a high reaction temperature of 680 ℃, the cubic lattice constant a was VN. close to the value. At 680 ℃, the highest nitridation temperature among the experimental conditions, the ammonia conversion rate was 93%, and no deactivation was observed.

• Analytical Science and Technology
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• v.21 no.1
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• pp.58-63
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• 2008

Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$. 0.3 g of TMA-A zeolite and 5 mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The incorporated nano-sized ZnO crystals and the crystallinity of TMA-A zeolite were evaluated by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The size of the incorporated nano-sized ZnO crystals was 3~5 nm, while the TMA-A zeolite was 60~100 nm. The bonding structure and absorption of the ZnO incorporated TMA-A zeolite were compared with the ZnO and TMA-A zeolite by the FT-IR analysis. Subsequentlly, the ZnO incorporated TMA-A zeolite showed the photoluminescent characteristics on the wavelengths of 330~260 nm and 260~230 nm by measurement of UV spectrophotometer.

• Journal of agricultural medicine and community health
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• v.35 no.4
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• pp.339-349
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• 2010

Objective: We surveyed awareness levels of brucellosis, Q fever and enterohemorrhagic Escherichia coli (EHEC) among dairy farmers in Gyeonggi Province to suggest directions for public education and public relations. Methods: We designed questionnaires to evaluate awareness of 3 major zooneses. We conducted a questionnaire survey to assess knowledge of the general characteristics of them, information sources for the awareness of zooneses, and the mode of transmission. Subjects were 716 workers from 482 dairy farms in Gyeonggi province. Results: The awareness levels for brucellosis, Q fever, and EHEC were 90.2%, 2.5% and 56.6%, respectively. Awareness of brucellosis and EHEC were tended to increase with higher number of school years. Television was the most common route of information for these zoonoses. Most common responses for questions concerning the method of transmission for each zoonoses, 'Contact with parturient fluid or placenta of animal' was 63.2% for brucellosis, 'Ingestion of raw meat or residual product' was 66.7% and 64.2% for Q fever and EHEC, respectively. The most common reason why dairy farmers think that it is difficult to prevent zoonoses was the inconvenience of wearing protection. Conclusions: Education programs for zoonoses, especially Q fever, are needed for dairy farmers. In addition, publicity information activities about prevention of zoonoses are needed for high risk groups, such as the dairy farmers surveyed.

• Proceedings of the Korean DIstribution Association Conference
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• 2001.11b
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• pp.125-141
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• 2001

In this paper, the current problems of logistics industry in Korea and their possible solutions were discussed. With Korea Telecoms KT-Logis, the supplier and demander of logistics service would not have to invest large sum of money into their computer system. All they need is just a computer with internet connected. What KT-Logis influence on the logistics industry are the following; 1. Many logistics service supplier and demander can do the business on the web with one computer system. 2. This web based computer system does not only work on the office but also apply on the field worker such as delivery personnel or even the forwarder with mobile phone. 3. KT-Logis is an integrated system which cover the broad arrange of logistics management from truck management to customer relations management. 4. Finally, KT-Logis is web based systems which suits for current e-business and mobile environment. In future, more studies should be done to develop more progressive integrated logistics information systems with enterprise resource planning(ERP) and supply chain management(SCM).

• Journal of Korean Home Economics Education Association
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• v.33 no.4
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• pp.15-30
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• 2021

This study was conducted to investigate the utilization and satisfaction of meal-kits according to food-related lifestyle among total 357 adults who had experience in using meal-kits. This study can provide basic data for effective menu composition and directions toward improvement. The participants of the study were classified into 5 groups 'health-type group', 'economic-type group', 'safety-type group', 'tasty-type group' and 'convenience-type group'. The 'tastye-type group' were found to spend more on purchasing meal-kits than other groups with the higher proportion(36.66%) of spending '30,000-50,000'won(p<0.05), which is the highest price category. The important factors that contributed to purchasing a meal-kits were 'taste'(50.98%), and 'economic-type group' showed the highest tendency of considering taste (58.46%). About half(49.02%) of the respondents preferred 'Korean-food' for meal-kits as for the type of food. All groups highly preferred 'meat'(42.58%) as the main ingredient, particularly the 'tasty-type group'(53.33%)(p<0.001). The 'tasty-type group' showed the highest satisfaction on 'convenience of cooking'(4.05), and 'convenience-type group' showed the lowest satisfaction on the 'origin of ingredient'(2.98) among groups (p<0.01). The overall response indicated that most respondents are willing to use meal-kits in the future (97.20%); and 93.28% of respondents would recommend the purchase of meal-kits to others, where 'convenience of cooking/purchase' was the factor contributing most for recommending(67.23%). Taken together, 'taste' was the most important factor for all groups. And 'Convenience of cooking' was the factor contributing to satisfaction most while 'origin of ingredient' contributing the least. It is recommended for the growth of meal-kits industry, to improve the quality of the meal-kits products and develop various menus.

• Journal of Preventive Medicine and Public Health
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• v.28 no.2 s.50
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• pp.511-525
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• 1995

To elucidate some DNA adducts as a biological marker for workers of chromate pigment, the effects of chromium exposure on the formation of 8-hydroxydeoxyguanosine(8-OH-dG) and sister chromatid exchanges(SCEs) frequency in 38 workers of a pigment plant in Bucheon which utilized lead chromates, were examined. The chromium contents of venous blood and urine were measured as working environmental exposure level. The concentrations of 8-OH-dG in DNA isolated from lymphocytes were determined with high performance liquid chromatography and electrochemical detector and denoted as a molar ratio of 8-OH-dG to deoxyguanosine(dG). The SCEs frequency were analyzed in DNA isolated from lymphocytes. A significant correlation was found between creatinine adjusted urine chromium concentration and the molar ratio of 8-OH-dG to dG(r=0.47, p<0.01). After adjusting the current smoking habit, the correlation coefficient was increased(r=0.62, p<0.05). However, there was no significant correlation between the SCE frequency and chromium exposure. This significant results between molar ratio of 8-OH-dG to dG and chromium exposure are in good agreement with in vitro studies that support the importance of DNA adduct formation for the carcinogenic effect of chromium.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.683-693
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• 2017

Transport biofuels have been recognized as a promising means to resolve the following issues like global warming, oil depletion and environmental pollutions. Among various biofuels, biodiesel has several advantages such as less emission of air pollutants and higher cetane values compared to diesel oil. Demand for biodiesel in Korea is increasing that leads to higher dependence on the imported feedstocks. Therefore, it is important to utilize the waste materials collected domestically for biodiesel production. Food waste oil collected in waste treatment facility has not been used for biodiesel production due to high free fatty contents in the oil. In this work, biodiesel conversion of food waste oil by Amberlyst 15 was studied. Synthetic and actual food waste oils have been used in the study. First, the effects of the major operating parameters including reaction temperature, methanol to oil molar ratio and catalyst loading on the conversion rates and yields were determined with synthetic waste oil. Kinetic modelling work was also done to determine the activation energy of the reaction. From the work, optimization reaction conditions were determined to be 383K, 1: 26.1 for methanol molar ratio to oil, 10 wt.% for catalyst loading and 360 min for reaction time. Activation energy of the reaction is determined to be 29.75 kJ/mol, lower than those reported in the previous works. So the solid catalyst, Amberlyst 15, was more efficient for esterification than the solid catalysts employed in the other works. Agitation rates have the negligible effects on the conversion rates and yields. With the identified optimization conditions, conversion of the actual food waste oil was also carried out. The esterification yield of actual food waste oil in 60 min was 13% lower than that of synthetic waste oil but the final yields in 240 min were similar each other, 98.12% for synthetic oil and 97.62% for actual waste oil.

• Journal of agricultural medicine and community health
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• v.34 no.1
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• pp.101-112
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• 2009

Objectives: Cattle slaughterhouse workers are known as the high risk group for the zoonoses. We surveyed the awareness of zoonoses among cattle slaughterhouse workers to suggest direction of education and public relations. Methods: We evaluated the epidemiological characteristics of zoonoses and the process of cattle slaughtering. We designed different questionnaires for the workers involved in slaughtering, the handlers of residual products, the inspectors and their assistants, and the grading testers and their assistants respectively. We visited 73 cattle slaughterhouses and 62 residual products handle houses across the country and conducted a questionnaire survey of the general characteristics and the awareness of zoonoses. The data collected was evaluated using the SPSS 17.0 statistical package. Results: The awareness rate of brucellosis, Q fever and Enterohemorrhagic Escherichia coli (EHEC) were 83.9%, 18.5%, 62.7% among cattle slaughterhouse workers. The awareness rate of zoonoses among the workers involved in slaughtering and the handlers of residual products was lower than other workers. The awareness rate of zoonoses tended to increase as the school career. In the correct awareness rate of the transmission of zoonoses, 'transmission by tick bite', 'person to person' and 'air transmission' were lower than other transmission items. The most common reason why cattle slaughterhouse workers think that it is difficult to prevent zoonoses was the ignorance of how to prevent. Conclusions: An educational program is needed for the cattle slaughterhouse workers on zoonoses especially Q fever. And publicity activities about prevention of infection are needed for high risk groups.