• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.2
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• pp.101-107
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• 2013

Cerium compounds such as Cerium hydroxide ($Ce(OH)_3$), Cerium chloride ($CeCl_3{\cdot}nH_2O$), Cerium carbonate hydrate ($Ce_2(CO_3)_3{\cdot}8H_2O$), Cerium oxide ($CeO_2$) were synthesized using recycled Ce precursor. Cerium(IV) oxide of nanoparticles were obtained by Ultra-sonication. Cerium-sodium- sulfate compound was synthesized through acid-leaching and addition of sodium sulfate from 99 wt% purity of Ce precursor as a starting material that was recycled from the waste polishing slurry. Moreover Cerium hydroxide was obtained from Cerium-sodium-sulfate compound by adding to sodium hydroxide solution. Then Cerium chloride was synthesized by adding of hydrochloric acid to Cerium hydroxide. Needle-shaped Cerium carbonate hydrate was synthesized in the continuous process and Cerium(IV) oxide with 30~40 nm size was subsequently obtained by the calcinations and dispersion.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.85-91
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• 2021

Aggregate waste separator with rotating separating net was designed for applying classification process of construction waste. In order to evaluate the performance of the aggregate waste separator, according to the type of waste, standardized waste samples are prepared using acrylic. The appropriate operating point was evaluated by the classification efficiency and misclassification rate of recycled aggregate according to the control frequency of the blower operating and inlet position of the separating net. The classification efficiency at the operating point of the aggregate waste separator was evaluated through flow analysis assuming recycled aggregate and waste sample as particles. As a result of the performance test, when the distance. between the conveyor belt and the inlet was 0.2m, the classification efficiency was 95%, but the misclassification rate of recycled aggregate was 2% or more, which satisfies the classification efficiency and the misclassification rate of less than 2%. The operating point was shown at a control frequency of 58Hz at a suction distance of 0.254m. As a resu lt of flow analysis, there was no misclassification of recycled aggregate. In order to redu ce constru ction waste in the existing recycled aggregate production process, adsorption system using a rotating separating net that can be operated as an installation type was built.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.124-132
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• 2022

The corrosion potential in concrete varies greatly with exposure and concrete mix conditions. In this study, RC (Reinforcement Concrete) samples were prepared considering cover depth, chloride concentration, and W/C(water to cement) ratio as variables, and HCP(Half Cell Potential) was measured, which evaluated comparative potential between embedded steel and concrete surface. In addition, OCP(Open Circuit Potential) was measured using buried steel and CE(Counter Electrode). Agar and NaOH solution were used as ion exchange materials and Hg/HgO was used for RE(Reference Electrode), which was more sensitive to temperature than HCP. Among the influencing factors, the exposure period and chloride concentration had a relatively greater effect than cover depth and w/c ratio. Additionally, the entire measured HCP and OCP showed a clearly linear relationship with increasing cover depth and w/c ratio. Through multiple regression analysis, the relationship between HCP and OCP was quantified, and an improved correlation was obtained with temperature effect.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.196-205
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• 2024

In this study, sample collection and quantification analysis of Tire and Road Wear Particles (TRWP) from the road surface were conducted to predict the amount of TRWP generated on the road surface moving by environmental compartment depending on rainfall intensity. Samples were collected from TRWP remaining on the road surface two days after the 3 days average rainfall (0-60 mm/day) occurred and the road surface was completely dry. Only TRWP were separated from the collected samples through size and density separation, and the difference in the content of TRWP remaining on the road surface after rainfall was based on the value of 60.2 g o f TRWP o n a day witho ut rain (0 mm/day). By calculating, it was co nfirmed that 0-49.4 g o f TRWP can mo ve to the environmental compartment depending on the intensity of rainfall. In addition, it was confirmed that when the rainfall intensity was 60 mm/day, the amount of TRWP moving to each environmental section was 3.75 times higher compared to 5 mm/day, and using the results of previous research, the total amount of TRWP that can be transported to the environmental compartment by rainfall from the domestic road environment annually is 9,592 tons, and 288 tons of this can be affected by marine microplastics. However, this study has limitations in terms of limited space and predicted results, but it would like to mention the need to improve the domestic road environment and sewage treatment system to reduce TRWP. In the future, we plan to conduct sample collection and concentration analysis studies of TRWP in real environmental compartments to verify the results of this study.