• Resources Recycling
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• v.2 no.2
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• pp.9-15
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• 1993

In this study, magnetite($Fe_3$$O_4$) from the converter dust of the Kwangyang steel making factory has been recove-red by means of the magnetic separation and the sedimentation column. The magnetite recovered from the dust is used for the preparation of Sr-ferrite instead of hematite. The results obtained in this study as follows : 1. The converter EP dust of the Kwangyang steel making factory are composed of $\alpha$-Fe, ($Fe_3$$O_4$) wustite etc. Magnetite in the converter EP dust is recovered by using sedimentation column and plastic bonding magnet. 2. It was confirmed that Sr-ferrite synthesis could be possible without oxidizing roasting of the magnetite. The steps of Sr-ferrite formation are proposed as follows : I$SrCO_3$ $+Fe_3$O$_4$+1/2(1-X)$O_2$longrightarrow$\alpha$ $-Fe _2$$O_3$ $+SrFeO _3$\ulcorner+$CO_2$II. $5.5\alpha$ $-Fe_2$$O_3$ $+SrFeO_3$\ulcornerlongrightarrowSrFe\ulcornerO\ulcorner+1/2(1/2-X)$O_2$3. By using magnetite from the dust insted of hematite, the hard Sr-ferrite magnet of (B.H)\ulcorner=2.64MGOe in the magnetic characteristics was succesfully prepared.

• Resources Recycling
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• v.22 no.5
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• pp.20-28
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• 2013

This study was carried out to evaluate the possibility of resource recovery for municipal solid waste(MSW) that sorted by a MBT system. First, physical property of MSW was similar to wastes carried into Sudokown landfill site. However, moisture of MSW was little higher than that. As a result of BMP test using organic fraction of MSW(OFMSWs), approximately 60 ~ 80 mL $CH_4/g$-VS of methane was occurred. Compared to the other studies, the value of methane is lower. It seems to be caused that high ratio of vinyl/plastic in OFMSWs. The other BMP test using sample of MBT system located in Sudokwon landfill was conducted each physical properties. According to the result of experiment, food waste makes 193 mL $CH_4/g$-VS, and paper is 102 mL $CH_4/g$-VS. However, there was not methane production in vinyl and rubber. Additionally, others that can't sort no more show 30 m $CH_4L/g$-VS of methane production. From the result of experimental data OFMSWs has high fraction of vinyl, rubber and other substance that difficult for biodegradation. Therefore it is need to sort of them.

• Resources Recycling
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• v.22 no.6
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• pp.3-11
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• 2013

This study was carried out to estimate greenhouse gas reduction potentials under treatment methods of combustible wastes excavated from closed landfill. The treatment methods of solid wastes were landfilling, incineration, and production of solid recovery fuel. The greenhouse gas reduction potentials were calculated using the default emission factor presented by IPCC G/L method of IPCC (Intergovernmental Panel on Climate Change). The composition of excavated waste represented that screened soil was the highest (65.96%), followed by vinyl/plastic (19.18%). This means its own component is similar to the other excavated waste from unsanitary landfill sites. Additionally, its bulk density was 0.74 $t/m^3$. In case of landfilling of excavated waste, greenhouse gas emission quantity was 60,542 $tCO_2$. In case of incineration of excavated waste, greenhouse gas emission quantity was 9,933 $tCO_2$. However, solid recovery fuel from excavated waste reduced 33,738 $tCO_2$ of the greenhouse gas emission quantity. Therefore, solid recovery fuel production is helpful to reduce of greenhouse gas emission.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.2 s.25
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• pp.107-113
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• 2006

Water treatment plant sludge occurred in sedimentation and inverse wash process is generally disposed by ocean dumping or reclamation after dehydration processing using mechanical or natural dry method. Recently, ocean dumping of sludge is limited actually by London Convention. Physical, chemical, and geotechnical characteristics of water treatment plant sludge were analyzed by experiments. The possibilities for recycling of the dehydration sludges as materials for covering sanitary landfill were examined. Experiments performed with sludges mixed with general soil to improved the sludge properties are the hydrometer analysis, the liquid and plastic limit test, the specific gravity test, the compaction test, and the unconfined compression test. The value of ${\gamma}_{dmax}$ is increased and OMC(Optimum Moisture Content) is lessened with mixed sludge. The value of maximum compressive strength and friction angle are increased and the cohesion is decreased with mixed sludge. The ratio between sludge and soil in mixed sludge was 3:7 and the strength of mixed sludge showed $3.6kg/cm^2$. These results satisfy the regulation of U.S. E.P.A regarding materials for covering sanitary landfill.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.276-284
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• 2022

In this study, performance evaluation and rheological characteristics were analyzed for recycling the fine powder of nuclear power plant dismantled waste concrete as a solidifying agent for radioactive waste disposal. The radioactive concrete fine powder was used to prepare a simulated sample, and the test specimen was prepared using Di-water, CoCl₂, and 1 mol CsCl aqueous solution as mixing water. Regardless of the aggregate mixing ratio and the type of mixing water, it satisfies the performance standard of 3.45 MPa for compressive strength at 28 days of age. All specimens satisfied the criteria for submersion strength, and the thermal cycle compressive strength satisfies the criteria for all specimens except Plain-50. As a result of evaluating the rheological properties of the solidifying agent, it was found that the increase in the aggregate mixing rate decreased the yield stress and plastic viscosity. The leaching index for cobalt and cesium of all specimens was 6 or higher, which satisfies the standard. In order to secure the stable performance of the solidifying agent, it is considered effective to use 40 % or less of the aggregate component in the solidifying agent.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.171-174
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• 2022

Cosmetic packing materials tend to be difficult to recycle when discarded due to the cosmetic industry's pursuit of aesthetics, functionality, and high value-added design. Pump packaging, which is widely used for the good preservation and discharge of cosmetics contents, is difficult to be separated and recycled because of a metal spring, which is in charge of pump resilience. In this study, a polypropylene spring was developed to replace the existing metal spring to improve the recyclability of the pump packaging for cosmetics, and was uni-materialized by applying to the cosmetic packing materials with 0.2 ml of discharge amount. In addition, performance test was conducted to verify the equivalence with the existing metal spring pumps as grounds for the commercialization of metal-free uni material pump packaging. The decompression leak test showed no leakage and displayed 14.8~17.5 N of pressing strength, 2.3~8.8 % of deviation in dispensing volume, and 4 occasions of pumping for initial discharge.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.83-91
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• 2023

This study investigate growth responses of Chinese cabbage and nitrogen use efficiency (NUE) to application of fermented organic fertilizer produced from domestic organic resources for developing alternative materials instead of imported castor oil meal. Two types of fermented fertilizers (Fermented Organic Fertilizer A (OFA) and Fermented Organic Fertilizer B (OFB)) were produced by mixing distillers dried grains 30%, sesame cake 30%, rice bran 20% and fish meal 20% under different fermentation conditions. Treatment consisted of OFA is fermented for 21 days on plastic greenhouse, OFB is fermented for 5 days on 40℃, and MOF (Mixed Organic Fertilizer) is a fertilizer made with castor bean as the main ingredient. OFA, OFB and MOF were applied at the rate of 320 kg N/ha. Chinese cabbages were cultivated from Aug. to Nov. in 2022. Growth and yield of Chinese cabbage were no significant differences among all treatments except control (non-fertilized, NF). However, NUE of Chinese cabbage was higher the fermented fertilizer treatment (OFB: 81.4%, OFA: 79.1%) than the MOF (65.3%). It was observed that urease activity in the fermented fertilizer treatment was significantly higher than the MOF. This result confirmed that fermented fertilizers have similar effect on growth and yield with the MOF and could improve the NUE of crop.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.91-99
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• 2009

This research were performed to evaluate co-incineration characteristics of sewage sludge and industrial waste in rotary kiln incinerator, and provide the fundamental data. Plastic portion (42.55%) in this industrial waste showed over 3 times higher than that (11.92%) of paper. Korean proximate analysis of the waste mixed with sewage sludge and industrial waste (3 : 7, volumetric basis) showed 16.3% of moisture, 70.5% of volatile solids, and 13.2% of ash, respectively. Low heating value of the mixed waste was 4,513kcal/kg. So it was thought that the mixed waste of sewage sludge and industrial waste (containing 43% of plastics and 12% papers) has enough heating value for co-incineration. The incineration of mixed waste showed the lowest SOx and NOx concentrations at $700^{\circ}C$. However, the operation at $950^{\circ}C$ was feasible in considering dioxin and the other hazardous gases. It was concluded that use of $Ca(OH)_2$ should be under investigation for the operation at $950^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.3
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• pp.77-86
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• 2010

In this study, the model of the indirect wind suction waste sorting machine for characteristics of the screening of waste was studied using computational fluid dynamics and the drag coefficient for the model and the suction wind speed were obtained. The wind separator are developing by installing a cyclone air outlet to the suction blower impeller waste is selective in a way that does not pass the features and characteristics of the inlet pipe of the pressure loss and separation efficiency can have a significant impact on. Using Wind separator for selection of waste in the waste prior research on the aerodynamic properties are essential. For plastic cases, it is reasonable to take the drag coefficient between 0.8 and 1.0, and for cans, compression depending on whether the cans, the drag coefficient is in the range from 0.2 to 0.7. The separation efficiency of waste as change suction speed was the highest efficiency when the suction speed was 25~26 m/s. Shape of the inlet, depending on how the transfer pipe of the duct pressure loss occurs because the inlet velocity changes through the appropriate design standards to allow for continued research is needed.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.261-270
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• 1999

In these days, construction activities have caused civil petitions associated with vibration-induced damages or nuisances. Therefore, it is strongly needed to develop a remedial technique to mitigate unfavorable effects. The objective of this experimental research is to investigate material and structural dynamic characteristics of vibration-controlled concretes which have been proportionally mixed with various vibration reducing material, such as latex, rubber powder, plastic resin, polystyrofoams and etc. Normal and high strength concrete specimens are also prepared for corresponding comparison. As part of the recycling research for obsolete rubber and plastic materials, 32 concrete cylinders and 10 concrete flexural beams have been made for material and structural dynamic properties, respectively. In accordance with the resonance test on concrete cylinders, it can be concluded that concrete with vibration-reducing material have relatively larger material damping ration than normal or high strength concrete. Styrofoam is determined to be very effective vibration-reducing mixtures. From the vibration test on 10 concrete flexural beams, meamwhile, of importance observations was that material damping ratio is very smaller than structural damping ratio of corresponding specimen. But further vibration test on more flexural beams should be strongly needed by varying support conditions.