• Asian Journal of Turfgrass Science
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• v.17 no.1
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• pp.19-33
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• 2003

The objective of this study was to evaluate the effects of crumb rubber recycled from used tires as a soil incorporation and topdressing materials on a trafficked Korean lawngrass‘Zenith’(Zoysia japonica). In Exp 1, incorporation treatments included three particle sizes (PS: coarse =4∼6.35 mm, medium =2∼4 mm, and One : less than 2 mm in diameter) and two incorporation rate (IR: 10 and 20%). Wear treatments were applied 30 passes per day by compactor weights being 60 kg with soccer shoes. Topdressing treatments included three PS and two topdressing depth (TD: 5 and 10 mm). Wear treatments were the same as described in Exp 1. In Exp 1, the treatment with medium PS+IR 20 resulted in the tendency to have high total clipping yield. There was no significant difference in clipping yield, turfgrass visual color, coverage, and root length among the treatments. Compared to control, tissue Zn levels increased about 6.5-fold by the treatments. The treatment with fine PS +IR 20 caused a less peak deceleration than coarse PS +IR 10. Total porosity, air-filled porosity, and capillary porosity increased with fine PS +IR 20. In Exp 2, compared to controls, however, there was a difference in turfgrass visual color after the termination of traffic treatment. There was no difference in root length. The treatment with fine PS + TD 10 resulted in the highest total clipping yield. As a result of soil physical analysis, soil penetration resistance was reduced by the treatments. The treatment with coarse PS resulted in a less peak deceleration than fine PS. In conclusion, turfgrass growth was increased by crumb rubber incorporation which enhanced soil physical properties. The crumb rubber topdressing was able to cushion the crown tissue area while still providing a smooth and uniform surface, improve overall turfgrass quality, and reduce compaction.

• Advances in concrete construction
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• v.10 no.2
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• pp.171-183
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• 2020

The main objective of this study is the assessment of the ability of limestone mortars to resist to different chemical attacks. The ability of polypropylene (PP) fibres waste used as reinforcement of these concrete materials to enhance their durability is also studied. Crushed sand 0/2 mm which is a fine limestone residue obtained by the crushing of natural rocks in aggregates industry is used for the fabrication of the mortar. The fibres used, which are obtained from the waste of domestic plastic sweeps' fabrication, have a length of 20 mm and a diameter ranging between 0.38 and 0.51 mm. Two weight fibres contents are used, 0.5 and 1%. The durability tests carried out in this investigation included the water absorption by capillarity, the mass variation, the flexural and the compressive strengths of the mortar specimens immersed for 366 days in 5% sodium chloride, 5% magnesium sulphate and 5% sulphuric acid solutions. A mineralogical analysis by X-ray diffraction (XRD) and a visual inspection are used for a better examination of the quality of tested mortars and for better interpretation of their behaviour in different solutions. The results indicate that the reinforcement of limestone mortar by PP fibres waste is an excellent solution to improve its chemical resistance and durability. Moreover, the presence of PP fibres waste does not affect significantly the water absorption by capillarity of mortar nether its mass variation, when exposed to chloride and sulphate solutions. While in sulphuric acid, the mass loss is higher with the presence of PP fibres waste, especially after an exposure of 180 days. The results reveal that these fibres have a considerable effect of the flexural and the compressive behaviour of mortar especially in acid solution, where a reduction of strength loss is observed. The mineralogical analysis confirms the good behaviour of mortar immersed in sulphate and chloride solutions; and shows that more gypsum is formed in mortar exposed to acid environment causing its rapid degradation. The visual observation reveals that only samples exposed to acid attack during 366 days have showed a surface damage extending over a depth of approximately 300 ㎛.

• Elastomers and Composites
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• v.44 no.3
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• pp.196-208
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• 2009

Sophisticated polymeric materials with 'responsive' properties are beginning to reach the market. The use of reversible, noncovalent interactions is a recurring design principle for responsive materials. Recently developed hydrogen-bonding units allow this design principle to be taken to its extreme. Supramolecular polymers, where hydrogen bonds are the only force keeping the monomers together, form materials whose (mechanical) properties respond strongly to a change in temperature or solvent. In this review, we describe some examples of hydrogen-bonded supramolecular polymers that can be utilized for self-healing materials. Synthesis of a rubber-like material that can be recycled might not seem exciting. But one that can also repeatedly repair itself at room temperature, without adhesives, really stretches the imagination. Autonomic healing materials respond without external intervention to environmental stimuli in a nonlinear and productive fashion, and have great potential for advanced engineering systems.

• Clean Technology
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• v.22 no.4
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• pp.274-280
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• 2016

In this study, it was to develop a chemical method that can recycle the cutting oil which accounts for about 25% of the cost of the process among containing materials of silicon waste sludge generated in the process for producing a solar cell wafer. The 7 types of reagents have been used, including acetone, HCl, NaOH, KOH, $Na_2CO_3$, HF, $CH_2Cl_2$, etc. for this experiment. And It was carried out at a speed of 3000 rpm for 60 minutes centrifugation after performing a reaction with a waste sludge at various concentrations. As a result, the best reagents and conditions for separating the solid such as a silicon powder and a metal powder and liquid cutting oil were identified as 0.3 N NaOH. It is found to be pH 6.05 in a post-processing recycled cutting oil with 0.3 N NaOH after reaction of waste sludge and 0.1 N HCl which is effective to remove metal powder in order to adjust the pH to suit the properties of the weak acid is a commercially available cutting oil and it showed excellent turbidity than when applied to sludge with 0.3 N NaOH alone. The results of FT-IR analysis which can compare the properties of the commercially available cutting oil shows it has a possibility of recycling oil. The cutting oil recovery rate obtained through the experiment was found to be 86.9%.

• Journal of the Korean Magnetics Society
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• v.27 no.3
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• pp.87-91
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• 2017

Carbon-encapsulated Ni and metal Ni nanoparticles were synthesized by levitational gas condensation (LGC). Methane ($CH_4$) gas was used to coat the surface of the Ni nanoparticles. The Ni particles had a core diameter of 10 nm, and were covered by 2~3 nm thin carbon layers with multi-shells structure.The low magnetization comparing with the Ni nanoparticles without carbon-shell results in the coexistence of nonmagnetic carbon and a large surface spin percentage with disordered magnetization orientation for the nanoparticles. Biginelli reactions in the presence of L-proline and Ni and carbon encapsulated Ni nanoparticles were carried out to change the ratio between stereoisomers. The obtained S-enantiomers for 3,4-dihydropyrimidine (DHPM) using catalysts of Ni, and Ni@C was an excess of about ${\Delta}{\sim}7.4%$ and ${\Delta}{\sim}19.6%$, respectively. The nanopowders were fully recovered using magnet to reuse as a catalyst. The Ni@C was shown at same yield to formation of 3,4-DHPM, though it was recycled for catalyst in the reaction.

• Land and Housing Review
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• v.1 no.1
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• pp.35-42
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• 2010

Most of the dredged sand generated from the sewage pipe maintenance project and the government's four-river project are disposed depending on abandonment and filling-up. This is caused by the lack of related recycling technology using dredged sand appropriately and high absorption rate and micro-particles of dredged sand producted from existing sand production system. Thus, this study carried out a quality assessment for the dredged sand produced through the optimum washing and sorting system supplementing problems of existing dredged sand production system as a part of research to examine performance of removing micro-particles and foreign substances. As a result of the assessment, the dredged sand produced through the cleaning and sorting system showed a wide quality improvement effect in absorption rate, 0.08 mm sieve pass amount, clay lump volume and organic impurity content, and it turned out to satisfy both the quality standards of this study, KS F 2573(recycled aggregate for concrete) and KS F 2526(aggregate for concrete) so it could be confirmed that it would be able to be used as an aggregate for concrete in the future.

• Journal of Hydrogen and New Energy
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• v.23 no.5
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• pp.421-428
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• 2012

The Sulfur-Iodine (SI) thermochemical hydrogen production process is one of the most promising thermochemical water splitting technologies. In the integrated operation of the SI process, the $O_2$ produced from a $H_2SO_4$ decomposition section could be supplied directly to the Bunsen reaction section without preliminary separation. A $HI_x$ ($I_2+HI+H_2O$) solution could be also provided as the reactants in a Bunsen reaction section, since the sole separation of $I_2$ in a $HI_x$ solution recycled from a HI decomposition section was very difficult. Therefore, the Bunsen reaction using $SO_2-O_2$ mixture gases in the presence of the $HI_x$ solution was carried out to identify the effect of $O_2$. The amount of $I_2$ unreacted under the feed of $SO_2-O_2$ mixture gases was little higher than that under the feed of $SO_2$ gas only, and the amount of HI produced was relatively decreased. The $O_2$ in $SO_2-O_2$ mixture gases also played a role to decrease the amount of a impurity in $HI_x$ phase by only striping effect, while that in $H_2SO_4$ phase was hardly affected.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.394-402
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• 2013

The new complex catalysts were synthesized by the reaction of titanium compounds (titanium chloride or titanium butoxide) and diamines in this work, and they showed very high catalytic activities for the cyclododecatriene (CDT) synthesis from 1,3-butadiene through trimerization. CDT synthetic reaction was performed in an autoclave reactor, and the effects of reaction temperature, type of catalyst, catalyst amount added into the system, the mole ratio of Al/Ti and immobilization method were investigated on the yield of product CDT. The titanium complex catalyst combined to diamine with 1:1 ratio showed high selectivity to CDT more than 90%. The ratio of TTT-CDT/TTC-CDT isomers in the product revealed as different values, depending on the type of diamine combined to titanium and Ti/diamine ratios. Those homogeneous complexes could be used as a heterogenized catalyst after anchoring on the supports, and the immobilized titanium catalyst retained the catalytic activities for several times in the recycled reactions without leaching. The carbon support containing titanium has exhibited superior activity to the silica support. Especially, when the titanium complex was anchored on the support which was fabricated by the hydrolysis of tripropylaminosilane itself, the resulting titanium catalyst showed the highest BD conversion and CDT selectivity.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.127-137
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• 2001

Polychlorinated biphenyls(PCBs) are halogenated aromatic compounds with the empirical formula $C_{12}$ $H_{10-n}$C $l_{n}$(n=1~10), and are a mixture of possible 209 different chlorinated congeners. PCBs were widely used as dielectric fluids for capacitors and transformers, plasticizers, lubricant inks and paint addirives. Once released into the environment, PCBs persist for years because they are so resistant to degradation. In addition to their persistence in the environment, PCBs in ecological food chains undergo biomagnification because of their high degree of lipophilicity. In 1970s, the worldwide production of PCBs was ceased and the import of PCBs was prohibited since 1983 in Korea. In spite of these actions, many PCBs seems to be still in use. The environmental load of PCBs will continue to be recycled through air, land, water, and the biosphere for decades to come. This study was conducted to measure the concentrations of PCBs in the serum samples of 112 women by GC/MSD and GC/ECD. The main results of this study were as follows. 1. PCBs were detected in all samples. The mean $\pm$SD levels of PCBs in the serum were 3.613$\pm$0.759 ppb, and median were 3.828 ppb. 2. The correlation coefficients of the concentrations of 13 PCB congeners were from minimum, 0.7913 to maximum, 0.9985, and all was significant(p=0.0001). The correlation coefficient between the concentrations of PCBs and p,p'-DDE was 0.9641(p=0.0001). 3. There was a positive association between age and PCBs' concentrations (simple linear regression ; $R^2$=0.86, $\beta$=0.08023, p<0.001). 4. There was a positive association between total lipids in the serum and PCBs' concentrations (simple linear regression ; $R^2$=0.7058, $\beta$=0.00486, p<0.001). 5. For possible predictors of PCBs and p,p' -DDE levels in the serum, age adjusted model (Y=$\beta$$_{0}$+$\beta$$_1$age+ $B_2$X) was applied. For BMI, major residential area, wether to eat caught fish by angling, where to eat caught fish by angling(by parents in the past), fish consumption, meat consumption, meat consumption, and dairy consumption, there was no association. For total conception frequency and lactation frequency and lactation period, there was negative association.ion.

• Journal of Environmental Health Sciences
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• v.19 no.4
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• pp.51-58
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• 1993

The integrated solid waste management for Seoul Metropolitan city can be established on the basis of the following hierarchy of priorities: 1. Efforts for source reduction should be propelled by both government and citizens to achieve the effects of resource conservation. The adequate production and consumption which are environmentally amenable and sustainable can be induced by the reasonable imposition of deposit money for waste treatment to one-time use products. To accomplish source reduction effectively, the induction of legal and institutional regulation of producer and consumer participation is requisite. 2. For resource recovery, wastes generated should be recycled as far as practicable. Community residents are responsible to separate discharge, the authorities concerned have responsibility of separate collection, and recycling industry should be assissted through tax reduction and financing. Resource separation facilities can be constructed at Kimpo Metropolitan landfill site for wastes not separately collected due to some unavoidable circumstances. 3. Garbage should be composted. Garbage is uneconomical for incineration, because it has high moisture content and low calorie, thus there is no reason for the incineration of garbage even though garbage is classified into combustibles. Composting facilities can be located at sites which are not densely populated and easily accessible to transportation, for example, Kimpo Metropolitan landfill site. Compost produced can be managed by the authorities for the use of fertilizer to a green tract of suburban land and farms. 4. Nonhazardous combustible wastes not recyclable can be utilized for thermal recovery at the incinerators which are completely equipped with pollution control devices. According to the trend of local autonomy and the equity principle of local autonomous entities, incineration facilities of minimal capacity required can be constructed at each districts of Seoul Metropolitan city which have organized local assembly. In case of Yangcheon district, the economically combustible waste quantity is about 260 tons/day which exceeds 150 tons/day, the incineration capacity of existing facility. But, from now on, waste quantity can be reduced substantially by the intensive efforts of citizens for source reduction and recycling and the institutional support of administrative organizations. Especially, it is indispensable for the government to constitute institutional and technological bases that can recycle paper and plastics form 43% of waste generated. A good time for constructing of incineration facilities for municipal solid waste can be postponed to the time that pollution control technologies of domestic enterprises are fully developed to satisfy the standards of air pollution prevention, because the life expectancy of Kimpo Metropolitan landfill site is about 25 years. Within this period, institutional improvements and technological advancements can be attained, while the air qual. ity of Seoul Metropolitan city can be ameliorated to the level to afford incineration facilities. 5. For final disposal, incombustibles and ash are landfilled sanitarily at Kimpo Metropolitan landfill site.