• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.499-504
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• 2005

Polymer concrete shows excellent mechanical properties and chemical resistance compared with conventional normal cement concrete. The polymer concrete Is drawing a strong interest as high-performance materials in the construction industry Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. Also the recycling of PET in polymer concrete would help solve some of the solid waste problems Posed by plastics and save energy. An objective of this paper is to estimate the damage of sulfuric acid, through investigating recycled PET polymer concrete, immersed at sulfuric acid solution for 84 days. As a result of testing, recycled PET PC, used $CaCO_3$ as filler, makes a problem of appearance and strength if they are exposed for long term at corrosion environment. On the other hand, recycled PET PC, used fly-ash as filler, had less effect on decrease in weight and strength. Recycled PET PC is excellent chemical resistance, resulting in the role of unsaturated polyester resin which consists of polymer chain structure accomplishes bond of aggregates and filler strongly. Also, recycled PET PC, used fly-ash as filler, is stronger resistance of sulfuric acid corrosion than $CaCO_3$, because it is composed of $SiO_2$ and very strong glassy crystal structure. Therefore, recycled PET PC, used fly-ash as filler, is available under corrosion circumstances like sewer pipe or waste disposal plant.

• Resources Recycling
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• v.19 no.1
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• pp.40-48
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• 2010

It was investigated that effects of NaOH concentration on synthesis of mesoporous materials using municipal solid waste incinerator ash slag (MSWI-ash slag). In order to increase the purity and maximize the amount of extracted Si content the raw MSWI-ash slag was mechanically activated. Extraction of Si from the MSWI-ash slag was carried out by alkali treatment using concentrated NaOH solution, which varied from 1M to 4M. Physical properties (i.e., pore size, specific surface area and total pore volume) of the synthesized mesoporous silica were also evaluated as a function of NaOH concentration via BET, SEM, TEM and small-angle X-ray scattering analyses. Over the entire range of NaOH concentration investigated (i.e., 1-4M), the synthesized mesoporous materials were determined to be SBA-15, which exhibited a hexagonal structure with the pore size of approximately 7 nm. On the other hand, specific surface area and total pore volume increased with NaOH concentration up to 3M while the values decreased at 4M, indicating that the optimal NaOH concentration for the synthesized mesoporous silica was approximately 3M. Further comparison analysis between two conditions (3M versus 4M) showed that the decrease in two physical properties at 4M NaOH concentration was likely due to the potential inhibition by excess Na ions on the formation of mesophase and the consequent increase of pore wall thickness by remaining Si ions.

• Resources Recycling
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• v.14 no.1
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• pp.17-25
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• 2005

In order to recover valuable metals from the waste electronic scrap, bioleaching of Cu, Zn, Al, Co, Ni, Sn and Pb was carried out using Thiobacillus ferrooxidans as a leaching microorganism in a shaking flask. In a preliminary study, to obtain the data on the leaching of Cu, Zn, Al, Co and Ni, the metal leaching was accomplished using metal powers instead of electronic scrap. The leaching percentaga of Cu, Zn, Co, Al and Ni powers was reduced with the increase of metal power concentration in solution. Below the metal concentration of 0.5 g/L, more than 85% of Cu, Co and Zn powers was leached out. At the electronic scrap concentration of 100 g/L, Thiobacillus ferrooxidans were able to leach more than 90% of the available Cu and Co while Al, Zn and Ni were able to leach less than 40%. Pb and Sn were not detected in the leachate. Pb was precipitated as PbSO$_4$, whereas Sn precipitated probably as SnO.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.90-94
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• 2006

The waste solution discharged from the LCD manufacturing process contains acids like nitric, acetic and phosphoric acid and metal ions such as Al, Mo and other impurities. It is important to removal of impurities to tess than 1ppm in phosphoric acid to reuse as an etchant because the residual impurities even in sub-ppm concentration in semiconductor materials play a major role on the electronic properties. In this study, we have been clearly established that a mixed system of solvent extraction, diffusion dialysis and ion-exchange technique, which made individually the most of characteristics is developed to commercialize in an efficient system for recovering the high-purity phosphoric acid. By applying vacuum evaporation, the yield of the process are almost 99% removal of nitric acid and acetic acid was achieved. And by applying the solvent extraction method with tri-octyl phosphate(TOP) as an extractant, the removal of acetic and nitric acid from the acid mixture was achieved effectively at the ratio O/A=1/3 with four stages and the stripping of nitric acid from organic phase is attained at a ration of O/A=1 with six stages by distilled water. About 97% and 76% removal of Al and Mo were achieved by diffusion dialysis. Essentially complete less than 1ppm removal of Al, Mo by using ion exchange ion resin and purification of the phosphoric acid was obtain.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.215-220
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• 2010

An experiment measuring the concentration ratios of $^{137}Cs$ and $^{85}Sr$ in fish as an index aquatic animal was performed. The species was Chinese minnow (Rhynchocypris Oxycephalus), a Korean native freshwater species. Chinese minnows were reared in acryl aquarium which was 45 cm wide, 85 cm long and 50 cm high. Water in the aquarium was successively purified using filtering devices attached on the floor and the wall. Fish powder in a particulate form was supplied twice a day for feeding. After a radioactive solution was added to make the initial water concentrations approximately $0.02\;{\mu}Ci/l$ and $0.1\;{\mu}Ci/l$ for $^{137}Cs$ and $^{85}Sr$, respectively, the fish and water were sampled 10 times for a month. The concentration ratios were measured to be $0.348lkg^{-1}\sim13.906lkg^{-1}$ for $^{137}Cs$ and $0.474lkg^{-1}\sim13.089lkg^{-1}$ for $^{85}Sr$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.63-71
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• 2011

A large volume of uranium electrokinetic leachate has been generated during the electrokinetic decontamination to remove uranium from contaminated soil. The treatment technology for the reuse of the uranium leachate was developed. The concentration of uranium in the generated uranium leachate was 180 ppm and concentrations of Mg(II), K(I), Fe(II), and Al(III) ions ranged from 20 ppm to 1,210 ppm. The treatment process for uranium leachate consisted mainly of mixing and cohesion, precipitation, concentration, and filtration. In order to obtain the pH=11 of a precipitate solution, the calcium hydroxide needs to be 3.0g/100ml and the sodium hydroxide needed to be 2.7g/100ml. The results of several precipitation experiments showed that a mixture of NaOH+0.2g alum+0.15g magnetite was an optimal precipitant for filtration. The average particle size of precipitate with NaOH+alum+0.15g magnetite was $600\;{\mu}m$. Because the total value of metal concentrations in supernatant at pH=9 was the smallest, sodium hydroxide should be added with 0.2g alum and 0.15g magnetite for pH=9 of leachate.

• Journal of Intelligence and Information Systems
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• v.11 no.2
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• pp.1-15
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• 2005

The explosive growth of the Internet leads to various on-line shopping malls and active E-Commerce. however, as the internet has experienced continuous growth, users have to face a variety and a huge amount of items, and often waste a lot of time on purchasing items that are relevant to their interests. To overcome this problem the comparison shopping systems, which can help to compare items' information with those other shopping malls, have been issued as a solution. However, when users do not have much knowledge what they want to find, a keyword-based searching in the existing comparison shopping systems lead users to waste time for searching information. Thereby, the performance is fell down. To solve this problem in this research, we suggest the Comparison Shopping System using Image Retrieval based on Semantic Web. The proposed system can assist users who don't know items' information that they want to find and serve users for quickly comparing information among the items. In the proposed system we use semantic web technology. We insert the Semantic Annotation based on Ontology into items' image of each shopping mall. Consequently, we employ those images for searching the items instead of using a complex keyword. In order to evaluate performance of the proposed system we compare our experimental results with those of Keyword-based Comparison Shopping System and simple Semantic Web-based Comparison Shopping System. Our result shows that the proposed system has improved performance in comparison with the other systems.

• Resources Recycling
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• v.7 no.3
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• pp.3-10
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was treated by adsorbing colloidal flotation using Fe(III) or Al(IlI) as flocclant and a sodium lamyl sulfate as a collector. Parameters such as pH, surfactant concentration, Fe(III) or Al(III) concentration, gas flow rate, etc., W앙e considered. The flotation with Fe(III) showed 99.8% removal efficiency of cohalt on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, and flotation time 30 min. When the waste solution, was treated with 35% $H_2O_2$ prior to adsorbing colloidal flotation, the optimal pH for removing cobalt shifted m to weak alkaline range and flotation could be applied in wider range of pH as compared to non-use of $H_2O_2$. Additional use of 20 ppm Al(III) after precipitation of 50 ppm Co(II) with 50 ppm Fe(III) made the optimal pH range for preferable flotation w wider. Foreign ions such as, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $Ca^{2+}$ were adopted and their effects were observed. Of which sulfate ion was f found to be detrimental to removal of cob퍼t ion by flotation. Coprecipitation of Co ion with Fe(III) and Al(III) resulted in b better removal efficiency of cobalt IOn 피 the presence of sulfate ion.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.17-26
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• 2003

The sorption experiment of cobalt was performed after the TRIGA soil was intentionally contaminated with cobalt was found that the sorption equilibrium coeficiency of soil decontamination was high when the ratio of soil mass to the volume of citric acid becomes 1:5 The TRIGA soil contaminated with 0.01 M, 0.001 M, and 0.0001 M of cobalt solution were decontaiminated with 0.01 M citric acid. The cobalt concentrtion in the wastewater were measured to be correspondingly 36.0, 14.0, 1.5 ppm. The results of wastewater recycling experiment by chemical precipitation method revealed that corresponding cobalt removal efficiency were 97% 88%. It was shown that the removal efficiency decreases as the cobalt concentration in the wastewater decreases. During the decontamination experiment, a lot of NaOH had to be added, and the volume of final solid waste reached almost 10% of that of the contaminated soil. The result of wastewater recyling experiment by ion exchange resin meted rethod revealed that to more the strong acid resins are used, the higher the cobalt removal efficiency becomes and the cobalt removal efficiency becomes and the lower the pH of recycling wastewater become. In order to obtain more than 95% removal efficiency, more than 0.625 g of strong acid resin was necessary in each of 3 experiments. There was an unexpected problem that a lot of strong acid resin waste was produced which amounts to 9.2% (volume) of the contaminated soil.

• Membrane Journal
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• v.8 no.2
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• pp.77-85
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• 1998

To treat effectively EDIR (electrodeposition ion removal) wastewater in terms of CO$_{Mn}$ 1,500~2,000 ppm generated from aluminum painting process, a RO (reverse osmosis) process was designed and installed to recover and reuse the concentrated solvent sent back to the electrocodeposition tank while the permeate reused as rinse water. A RO system in which three polyamide-spiral wound modules ($102\Phi \times 1,016L$ mm) connnected in series had been running to treat 20 m$^3$ in waste volume in 3 days batch operation at the condition of system recovery of 30 %, applied pressure 11.5 $kg_f/cm^2$ and room temperature. During 42 hours continuous operation leading to 5-fold decrease in waste volume, nearly constant permeation flux of 390 l/m$^2$-hr was maintained and the permeate with average CO$_{Mn}$, 300 ppm was obtained which could be used for washing the remaining paint solution in ion-exchange tower instead of demineralized water. Also COD$_{Mn}$ rejection as a function of running time was observed to be in the range of 78~87 % and the observed solvent rejections for ethyl cellusolve, buthyl cellusolve and n-butanol were 79 %, 87 % and 70 %, respectively.