• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.110-116
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• 2002

The aim of this study was to analyze food waste treatment cost and to estimate effect of by-product, such as wastewater and foreign materials, on amount cost. In cost analysis, man power and facility capacity are fixed, whereas operation cost, by-product treatment and et, al. are varied by treatment methods. The rate of by-product treatment cost in amount cost are between 5% and 39%. The methods which consume large electric power or generate much wastewater showed higher rate of by-product treatment cost in range of 14 to 39%. On the other hand, the methods which have simple process showed lower rate in range of 5 to 11%. Thus, this study recommend that by-products should be treated in sewage treatment facilities or landfill sites to prevent illegal disposal of by-products or to reduce burden of by-product from private sectors.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.93-104
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• 1999

Existing composting system was improved to have a high performance for organic degradation, deodorization and energy reduction. Compared with conventional devices, this developed system uses the heat recovered from platinum catalytic tower by three times heat exchange in which 65% of exhaust gas was recirculated. Evaporation of water was made easy by maintaining negative pressure in entire system. It was possible for reaction to be maintained steadily by microorganism agent. The optimum mixing volume ratio of garbage to sawdust was 15:1 contrary to 20:1 in conventional one. Moreover, aerobic condition was maintained efficiently. Effects obtained by using a inner circulation system were as follows. It was possible to reduce the ammonia causing offensive odor and verified that consumption of electricity cut down to 1/3 with reduction of exhaust gas inflowing. According to this inner circulation, the optimum air flow was $0.44m^3$ to 100kg treatment capacity. The electricity consumption was changed in proportion to inflowing air volume.

• Resources Recycling
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• v.27 no.3
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• pp.39-47
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• 2018

According to Vietnam government establishes additional coal-fired power plants to secure generation capacity, emission of ashes is accelerating and processing them is urgent issue. This study targeted utilize fly ashes that occurred in circulating fluidized bed combusion (CFBC) power plant to use ground solidification materials. CFBC fly ashes are used to make solidification with ground granulated blast furnace slag (GGBFS), gypsum and cement. Then produced specimens by mixing with soft ground soil to confirm mixing effect of fly ash in solidification. As a result it was possible to find mixture design that is satisfied 3 MPa compressive strength in age 28 days and reduce weight loss rate over 50% in acid immersion test than plain specimens that using only ordinary portland cement.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.27-31
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• 2017

This study was performed to estimate bubble dissolution rate by change of hydraulic pressure according to increase of water depth. Experimental results showed that airflow rate was decreased by increase of hydraulic pressure. Because the force which acts on outlet of nozzle was increased by increase of hydraulic pressure. Mass-transfer coefficient decreased with decreasing airflow rate and increasing effective volume due to increase of hydraulic pressure as water depth increased. On the contrary, as the water depth increased, the bubble dissolution rate was increased because longer residence time of microbubble which was generated by ejector type microbubble generator. However it was thought that if water depth for capacity of ejector type microbubble generator is excessively increasing, bubble dissolution rate would be reduced due to low airflow rate and mass-transfer coefficient. Therefore, it is importance to consider the water depth when operating ejector type microbubble generator.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.521-528
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• 2017

To find a recycling method for waste liquid crystal display (LCD) panel glasses, we investigated the synthesis process of zeolite with an ion exchange ability by hydrothermal reaction using waste LCD panel glass as a raw material. It was shown that the waste LCD panel glass can be used as a raw material for the production of zeolites having the ion exchange ability. Following conditions for the synthesis of the zeolite with an ion exchange ability were required : the molar ratio of Si to Al components of the waste LCD glass needs to be 2.0 to 2.8, and the temperature of $100^{\circ}C$ and reaction time of 12 hours are needed for the hydrothermal reaction. Based on the required conditions previously mentioned, the A type zeolite was synthesized when the molar ratio of the Si to Al component was 2.0, and the P type zeolite was produced when the molar ratio was 2.8. The type A zeolite synthesized by using the waste LCD panel glass showed a good ion exchange ability and heavy metal adsorption ability. Also, an excellent ion exchange capacity was observed as the crystal phase grows stably in a cubic phase.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.92-96
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• 2003

The on-site sewage sludge vermicomposting equipment was designed and evaluated on the batch and continuous tests. The vermicomposting equipment was designed to consider the mechanization as well as automation. In terms of performance evaluation of equipment with continuous experiments, the highest treatment rate was found in the condition of 5mm in particle size and 10mm in e feeding height. Also, 20~25kg of earthworm per 50kg of sewage sludge was the most appropriate density of earthworm. In addition, the most effective separation of cast was found when the earthworm breeding box height was 80cm. The performance evaluation on equipment allowed the establishment of earthworm composting capacity of 2ton per a day with a size of $5{\times}3{\times}1m$ and the automatic control devices.

• Resources Recycling
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• v.16 no.6
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• pp.46-51
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• 2007

This study aimed at developing high-efficiency RDF(refuse derived fuels) fuel in order to use RDF energy rationally and to recycle industrial product. As most studies in this area are concentrated in large combustion apparatuses such as kilns, but this study was focused on the small-sized heating systems, applying them directly to grate type boiler which has a heating capacity of $66{\sim}132m^2$. The different kinds of fuel are experimented including RDF. Coke and Waste Tire. First, for this, we experimented and analyzed RDF to see the change in its mass and heating value. Also, four kinds of exhaust gas are sampled by gas analyzer including CO, $CO_2$, NO and $NO_2$ at different temperature. As a result, the levels of CO concentration of RDF are higher than these of coke and waste tire. But, the levels of NO, $CO_2$ and $SO_2$ concentration of RDF and coke were lower then the levels when waste tire is burned.

• Resources Recycling
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• v.22 no.5
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• pp.3-12
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• 2013

It is necessary to manage risk of metals which are has rigid supply structures and expected demand expansion, considering to industry structure and resource securing capacity of each country. Countries conducted various criticality analyses and selected mainly rare metals as critical materials(or Critical metals or Critical raw materials). This study examined cases of metals risk evaluation and management which are based on technology changes and imbalance supply-demand. EU and U.S.A evaluated risk on metals needed as supply expansion of renewable energy. Japan forecasted demand of rare metals needed in Japan's growth engine industry. U.K analyzed criticality of metals, considering environmental burden occurred from mining to refining. Critical materials has features such as weak price signal, inelastic supply structure, demand volatility in technology change.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.267-274
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• 2010

We assessed the effect of Se-methylselenocysteine (MSC) treatment, at a dose of 0.75 mg/rat/day for 1 or 2 weeks, on the activities of antioxidant systems in Sprague-Dawley rat tissues. Significant changes in glutathione and antioxidant enzyme activities, with different patterns among tissues, were evidenced. Glutathione content and its reduction state in the liver, lung, and kidney were elevated upon MSC treatment, whereas they were significantly lowered in the spleen. Among the tissues exhibiting glutathione increase, there were different enzymatic responses: $\gamma$-glutamylcysteine ligase activity, the rate-limiting enzyme in the glutathione synthesis pathway, was increased in the liver, whereas the activities of the enzymes associated with glutathione recycling, namely, glutathione peroxidase, glutathione reductase, and glucose 6-phosphate dehydrogenase, were significantly increased in the lung and the kidney. The superoxide dismutase activity was decreased in all tissues upon MSC treatment, whereas catalase activity was increased in all tissues but the liver. Lipid peroxidation level was transiently increased at 1 week in the lung and the kidney, whereas it was persistently increased in the spleen. The increase was not evident in the liver. The results indicate that the MSC treatment results in an increase in the antioxidant capacity of the liver, lung, and kidney principally via an increase in glutathione content and reduction, which appeared to be a result of increased synthesis or recycling of glutathione via tissue-dependent adaptive response to oxidative stress triggered by MSC. The spleen appeared to be very sensitive to oxidative stress, and therefore, the adaptive response could not provide protection against oxidative damage.

• Resources Recycling
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• v.11 no.3
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• pp.3-9
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• 2002

Relnoval of ammonia from aqueous solutions has been studied with zeolite and bentonite minerals. Zeolite and bentonite powder were supplied by a domestic company and used as delivered without further purification. The aqueous pH was found to increase by addition of zeolite or bentonite up to pH 8.5 from initial pH of 5.5∼5.7. From the C.E.C. measurement by ammonium acetate leaching method, the values of C.E.C. of zeolite and bentonite sample were observed to be 129.7 meq/100 gr and 65.1 meq/100 gr, respectively and Na+ ion accounted for the major part of total C.E.C. in both cases. In the removal of ammonia with zeolite and bentonite, physical adsorption of ammonium ion onto minerals was believed to contribute to the removal of it as well as the intrinsic cation exchange reaction. Finally, zeolite was found to be superior to bentonite in the removal of ammonia from aqueous solutions.