• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.207-215
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• 2015

In the last decade, increasing national research fund for recycling the waste FRP (fiber reinforced plastics) ships which has caused environmental problems, improves the technology making concrete-reinforcing fibers out of the waste FRP. Furthermore, the concrete with recycled FRP fiber was tested for the structural performance. Experimental strength tests show that use of recycled FRP powder does not reduce the compressive strength of high strength concrete, and does increase the fire resistance performance of high strength concrete significantly. But, the study in investigating the properties of recycled fiber powder from waste FRP has not been completed because of the absence of the method of separation of mat layer from the waste FRP. This study is to propose a new extracting method of the mat layer from waste FRP, which is the efficient and environment friendly system. and thus it is considered to be the useful recycling method for fire resistance high concrete products or structures.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.283-290
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• 2002

Generally polymer mortar and concrete using unsaturated polyester resin has high strengths and good chemical resistance. However it also has high brittleness and because of this reason, it is not used for the purpose that demands high resistance to impact. The purpose of this study is to improve the brittleness of unsaturated polyester mortar(UPE mortar) which could be used for the flooring material with recycled aggregates and UPE. Polyurethane liquid rubber(PU) and recycled aggregates were used to complement the brittleness and to recycle the resources respectively. The characteristics of mortar were investigated according to the molecular weight and substitution rate of PU. As the molecular weight and PU substitution rate were increased, the viscosity was increased, working life became fast and curing shrinkage was reduced. Compressive and flexural strengths were also reduced but tile brittleness was improved. Therefore, it is seemed that the improved WE mortar could be obtained by using polyurethane liquid rubber with the polyol of molecular weight 2000, 3000.

• Journal of Environmental Science International
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• v.27 no.11
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• pp.937-946
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• 2018

This study investigated the applicability of horticultural media with recycled coir substrates the growth of Chinese cabbage (Brassica campestris L. ssp. Pekinensis) and lettuce (Lactuca sativa L.) crop. The six different types of coir based substrates were A, Coir 45: Perlite 35: Vermiculite 12: Zeolite 8 (%), B, Coir 55: Perlite 25: Vermiculite 12: Zeolite 8 (%), C, Coir 65: Perlite 15: Vermiculite 12: Zeolite 8 (%), D, Coir 75: Perlite 5: Vermiculite 12: Zeolite 8 (%), E, Coir 85: Perlite 5: Vermiculite 5: Zeolite 5 (%) and F, nursery media (control). The pH and Electric conductivity of the horticultural nursery media were 6.06-7.00 and $0.45-1.10dS/m^{-1}$, respectively. The nursery media containing coir substrates had higher level of Total N, Ca, K, Mg and P than those without coir. Additionally, it was observed that the growth of Chinese cabbage was the best on D (containing 75% coir) while that of lettuce was the best on E (containing 85% coir). In general, when substrates containg a higher percentage of coir were used, the growth of Chinese cabbage and lettuce was ideal. Additionally, the P, Ca, and Mg content in both plants was not significantly altered by the amount of coir present in the media. However, with an increase in the amount of coir substrate, the chlorophyll, N, and K content was increased. After harvesting, there was no significant difference in the chemical properties of the horticultural nursery media of both plants. Thus, it can be suggested that, coir substrate after a single use could be recycled as horticulture nursery media.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.56-63
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• 2020

The usage of OPC-free alkali activated ground granulated blast furnace slag(GGBS) mortar has been widely studied on the previous years, due to its advantages on sustainability, durability and workability. This paper brings a new view, aiming to classify the best application in situ for each mortar, according to the type and activator content. By this practical implication, more efficiency is achieved on the construction site and consequently less waste of materials. In order to compare the different activators, the following experiments were performed: analysis of compressive strength at 28 days, setting time measured by needles penetration resistance, analysis of total pore volume performed by MIP and permeability assessment by RCPT test. In general, activated GGBS had acceptable performance in all cases compared to OPC, and remarkable improved durability. Following the experimental results, it was confirmed that each activator and different concentrations impose distinct outcome performance to the mortar which allows the classification. It was observed that the activator Ca(OH)2 is the most versatile among the others, even though it has limited compressive strength, being suitable for laying mortar, coating/plaster, adhesive and grouting mortar. Samples activated with NaOH, in turn, presented in general the most similar results compared to OPC.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.130-137
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• 2018

In the construction industry, research on alkali activated cement using fly ash or blast furnace slag fine powder has been published in Korea and abroad as a way to reuse industrial byproducts without using cement at all and to obtain economical effects at the same time. the purpose of this paper is to evaluate the effect of the ratio and coefficient of hydration ratio and lime saturation degree on the strength of alkali activated slag cement by chemical quantitative analysis of alkali activated slag cement used in the management of existing portland cement. as a result, it was confirmed that the ratio and coefficient of hydration ratio and lime saturation are all within a certain range.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.69-72
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• 2005

Recently, there have been many studies seeking towards the utilization of cementitious powder from concrete waste as recycle cement. However, most of the studies actually have been researches about the reuse of mortar or paste, not concrete waste. In fact, either mortar or paste is quite different from a real concrete waste in terms of age and mixture. Thus the purpose of this study is to examine basic physical properties of recycle cement, manufactured with cementitious powder from concrete waste, and analyze differences in chemical and hydraulic properties of the cement and its tested model. As a result of the chemicai analysis, recycle cement is composed mainly of CaO and SiO2, and that it is even lower in the content of CaO than Portland cement, which is also supported by previous studies. But, Differently from previous studies, plastic working at the temperature of 650 was found an optimal condition under which cementitious powder from concrete waste could restore its hydraulic properties.

• KIEAE Journal
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• v.12 no.2
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• pp.125-129
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• 2012

With the development of the industry, such as homes and industries of electric energy usage and thereby increase the supply of electrical energy for power generation facilities were also increased. Among them an increase in thermal power plants, such as Bottom Ash was accompanied by an increase in industrial waste. If fly ash is recycled, some ten thousand Fly Ash and Bottom Ash Landfill, the recycling rate is low in most. In this study, in order to resolve the problem of fly ash recycling Bottom Ash to take advantage of low physical and chemical characteristics were analyzed. Evaluation of Physical Properties of Bottom Ash In addition, through the evaluation of functional properties of additives chogyeol condensation of 1 hour or more, within 3 hours of closing, Flow has more than 190mm of wheel load resistance value is less than 3mm flooring developed to study the subsequent emphasis on the Properties is based. Through these studies by developing a functional flooring help with the problem of resource depletion, and losses due to reclamation and pollution is to prevent.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.225-227
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• 2011

This study investigates the effect of crushed fine aggregate and chemical admixture (durability improvement agent, named DIA) on blast furnace slag-based brick. The control brick was made with recycled fine aggregate of 100% and, no cement was used. Test results showed that all specimens developed similar strength, except for the specimen without partial replacement of crushed fine aggregate at 3 days. However, it is interesting to note that this specimen without crushed fine aggregate resulted in the highest strength at 7 days. In addition, the DIA had a major effect on the absorption ratio of brick specimens. For the brick specimens with partial replacement of crushed fine aggregate with 10%, the addition of DIA with only 1% was enough to satisfy the code regulated by KS F 4004.

• Journal of Powder Materials
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• v.18 no.3
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• pp.277-282
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• 2011

[ $LiCoO_2$ ] a cathode material for lithium rechargeable batteries, was prepared using recycled $Co_3O_4$. First, the cobalt hydroxide powders were separated from waste WC-Co hard metal with acid-base chemical treatment, and then the impurities were eliminated by centrifuge method. Subsequently, $Co_3O_4$ powders were prepared by thermal treatment of resulting $Co(OH)_2$. By adding a certain amount of $Li_2CO_3$ and $LiOH{\cdot}H_2O$, the $LiCoO_2$ was obtained by sintering for 10 h in air at $800^{\circ}C$. The synthesized $LiCoO_2$ particles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.454-457
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• 2011

We report the preparation of nanocrystalline cobalt ferrite, $CoFe_2O_4$, particles using recycled $Co_3O_4$ and their surface coating with silica using micro emulsion method. Firstly, the $Co_3O_4$ powders were separated from waste cemented carbide with acid-base chemical treatment. The cobalt ferrite nanoparticles with the size 10 nm are prepared by thermal decomposition method using recycled $Co_3O_4$. $SiO_2$ was coated onto the $CoFe_2O_4$ particles by the micro-emulsion method. The $SiO_2$-coated $CoFe_2O_4$ particles were studied their physical properties and characterized by X-ray diffraction (XRD), high resolution-transmission electron microscopy (TEM) analysis and CIE Lab value.