• Journal of Environmental Science International
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• v.25 no.8
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• pp.1077-1085
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• 2016

The present study was investigated the effect of recycled coir organic substrates on the growth of different vegetable crops. The recycled coir had better physical and chemical properties than the new coir. The growth of tomato plant was better on the coir substrate that had been used for 2 years than that on the new coir substrate. The average number of tomato fruits was 108 on the new coir substrate, while it was 179 and 165 on the coir substrate used for 1 and 2 years, respectively. The growth of cherry tomato plant was also better on the coir substrate used for 2 years than that on the new coir substrate. The average number of cherry tomato fruits was 43 on the new coir substrate, while it was 206 and 164 on the coir substrate used for 1 and 2 years, respectively. The growth of brussel sprout was better on the coir substrate used for 3 years than that on the new coir substrate and the average number of brussel sprout leaves was 26.8 on the new coir substrate, while it was 34.3 on the coir substrate used for 3 years. The growth of Korean cabbage improved on the coir substrate used for 1 years compared to the new coir substrate and the number of leaves was 15.1 on the new coir substrate, while it was 24.3 on the coir substrate used for 1 year. Thus, used coir can be recycled to improve vegetable yields compared to using new coirs.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.4 no.2
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• pp.24-32
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• 1998

This study examined the effects of recycling on chemical pulp fibers from multiple recycles. Firstly, water-pretreated alkaline photocopy paper was disintegrated by TAPPI standard disintegrator at room temperature. After dewatering, this pulp was dried in oven at $80^{\circ}C$ for 24hrs. A sequence of wetting, disintegrating and drying was one recycling cycle and this cyclic treatment was repeated from zero to five times. The recycled handsheet dropped to 90% of the original brightness after five cycles, and lost the most brightness in the first two cycles. However, it had a gain of 10% in opacity after five cycles. And, in this study, the method for determining residual ink(toner) content in recycled handsheets were estabilished by means of SEM-EDX and atomic absorptive photometer. The change of residual ink percentage on recycled paper showed the effect of recycling numbers on deinkability of waste paper. A slight decrease in deinkability was noted for the recycled handsheets, which may be due to the change of fiber surface free energy connected with fiber swelling.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4003-4006
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• 2012

A novel copper nanoparticles were synthesized from cupric sulfate using hydrazine as reducing reagents. A series of aromatic nitro compounds were reacted with sodium borohydride in the presence of the copper nanoparticles catalysts to afford the aromatic amino compounds in high yields. Additionally, the catalysts system can be recycled and maintain a high catalytic effect in the reduction of aromatic nitro compounds.

• Resources Recycling
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• v.19 no.3
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• pp.62-70
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• 2010

As the demand for paper continues to grow and the importance of recycled paper, white ledgar(WL) and old newspaper pulp(ONP), continuously increase. In addition, usage of recycled paper is essential in terms of forest conservation and environmental protection issues. However, optical and mechanical properties of recycled paper have some drawbacks than regular paper's properties that is indispensable. In order to complement these problems of recycled paper, precipitated calcium carbonate (PCC) was synthesized by the In-situ process with a recycled pulp. Depending on the size of PCC is divided into 2 types, $0.01{\mu}m{\sim}0.09{\mu}m$ colloid type ultra-fine particle and $0.1{\mu}m{\sim}0.9{\mu}m$ cubic type particles. In this study, we analyze how the different shape and size of precipitated calcium carbonate affects in the optical and mechanical properties of the recycled paper used as a filler. Furthermore, we mixed with chemical pulp for overcome reduce of mechanical properties, without using other chemicals, when we use PCC as a filler. The results has the possibility to meet in GR excellent recycling certification mark, standard was proposed.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.329-340
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• 2016

Increase in demotion and repair works on buildings in the construction market generates a large amount of construction waste. Recycling of construction waste is important for saving of resources, preservation of environment and constant advance of the construction industry. Accordingly, the environmental and economic value of recycled aggregate, which is produced after waste concrete is crushed, is increasingly highlighted. It is generally known that compared to concrete made of ordinary aggregate, concrete made of recycled aggregate has low quality, and the low quality is dependent on the amount of the bonding heterogeneous (cement paste and mortar) as well as the amount of the pores within the bonding heterogeneous. Reports on carbonation mechanism shows that the pores of cement-based materials are filled up by the progress of carbonation. Therefore, this study aims at an estimation of the period for optimum carbonation reforming appropriate for the thickness of the bonding heterogeneous of recycled aggregate, based on carbonation mechanism, with a view to improving the product quality by means of filling up the pores of the bonding heterogeneous of recycled aggregate. This study drew the carbonation depth according to the passage of age by calculating the bonding ratio and bonding thickness of the bonding heterogeneous as against the particle size distribution of recycled aggregate as well as by chemical quantitative analysis according to the age of accelerated carbonation of mock-up samples imitating bonding heterogeneous. Based on the correlation between the age of accelerated carbonation and carbonation depth, this study also proposed the estimated period of carbonation reforming of recycled aggregate appropriate for the thickness of the bonding heterogeneous.

• Journal of the Korean Geosynthetics Society
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• v.2 no.3
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• pp.25-38
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• 2003

Geotextile composites to improve the resistance to the application environment were manufactured of recycled polyester geotextile with carbon black as ultraviolet stabilizer and polypropylene geotextile by needle-punching method. Mechanical properties, ultraviolet resistance and chemical stability were evaluated. Retention ratio of tensile properties of polypropylene geotextiles were decreased about 50% with the exposed condition by ultraviolet but those of geotextile composites showed the slightly decrease. Geotextile composites which have larger weights of recycled polyester geotextile were more stable against ultraviolet. For chemical stability, the changes of tensile strength values of geotextile composites were in the range of -20~+10% at the various chemical conditions.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.277-282
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• 2015

This study is conducted to utilize waste concrete powder (WCP) made as a by-product manufacturing high quality recycled aggregate. The blaine fineness of the used waste concrete powder was $928cm^2/g$. As the main characteristic of waste concrete powder, it showed an angular type similar to cement, but hydrated products were attached on the surface of particles. In addition, the size of the particles of waste concrete powder was larger than OPC and in terms of chemical components it had higher $SiO_2$ contents. For using WCP in soil cement-based pavement, the qualities, physical and chemical properties, of WCP should be researched. In the first step, the specified compressive strength of mortar for two types of clay sand soil and clay soil respectively was experimented to be 15 MPa and then optimum mixing ratio of chemical solidification agent were decided in the range of 1.5 - 3.0% in the replacement with cement weight content. In the second step, based on the prior experimental results, recycling possibility of WCP in soil cement-based pavement was studied. In the result of experiment the mixing ratio of WCP were 5, 10, 15 and 20% in the replacement with soil weight and the compressive strength of mortar was somewhat decreased according to the increase of the mixing ratio of WCP.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.70-78
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• 2023

Blast furnace slag, a by-product of the steel industry, is mostly recycled as concrete admixture, but electric arc furnace slag has not been recycled to date. In particular, since electric arc furnace slag partially contains free lime (free-CaO) in the discharge, it is necessary to review this in order to recycle f or construction materials. Recently an atomizing process which is a method of rapidly cooling electric arc furnace slag has been developed and applied. Therefore, in order to use the fine aggregate of oxidized slag from electric furnace restored by this method as an aggregate for concrete, physical damage and chemical reviewing are required. In this study, a physical and chemical review was conducted on the fine aggregate of Electric Arc Furnace Oxidizing Slag (EFOS) as a by-product of the steel manufacturing process with atomizing process. In this experimental study, EFOS was experimentally examined about whether it can be used as concrete fine aggregate. Also, we intend to provide basic data for the future use of the EFOS fine aggregate. As a result of the experimental study, it was found that the fine aggregate of the EFOS satisfied the quality standards of the fine aggregate for concrete in most items specified by Korean Standard.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.212-212
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• 2006

Polyurethane wastes can be depolymerized with glycols and/or amines. The depolymerization products may be recycled for the preparation of various polyurethanes. Caprolactam was employed to depolymerize Spandex fibers and the depolymerization products were evaluated as raw materials for the preparation of polyurethane elastomers. The depolymerization products were homogeneous and could be used to prepare polyurethane elastomers acceptable for various applications as binders.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.635-641
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• 2014

Archaeological waterlogged woods require a process of dimensional stabilization for their conservation. PEG is the most widely used in the conservation of archaeological waterlogged wood. One of the easiest and commonly used methods is the impregnation of 40% polyethylene glycol followed by vacuum freeze drying. However, the waste fluid produced from the PEG treatment is black in color and has a severe odor due to the organic matter extracted from the wood. Thus It cannot be recycled and it was just thrown out. Color of waste fluid can be decolored with oxidation reaction by hydrogen peroxide. Properties of PEG before and after preservation treatment, and after oxidation with $H_2O_2$ were not changed. Dimensional stability of archaeological waterlogged Salix koreensis Andersson was studied with pure or recycled PEG. The ratio of impregnation solutions were 10:0, 7:3, 5:5, 3:7, 0:10 (pure PEG : recycled PEG). Impregnation process was carried out by putting the wood specimens 10% PEG solution for 5days, 20% for 5 days, 30% for 5 days finally 40% for 5 days. All of the specimens showed the weight change rate of 25%. SEM results provided that the dimensional change of were less than 4% PEG impregnated specimens. Comparing with pure PEG impregnation system, conservation precess mixed PEG also showed no significant changes. Conclusively, the recycled PEG can be used for archeological waterlogged wood conservation precess.