• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.137-142
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• 2018

Recycled synthetic resin materials produced from waste vinyl and waste plastic contain many foreign substances. Plastic products made from this recycled resin materials containing foreign substances are of poor quality, with reduced the strength and rigidity. Foreign substances include heavy metals, cement, foil, dyed paper and dust. In this study, the scratch-Dies process; which remove foreign sbustances, with precision and automation, through a three-stage mesh filter, is designed. The process is evaluated with finite element analysis according to vibration loading and make. After installing the manufactured equipment, recycled resin was producde, and its heavy metal content was evaluated. Recycled synthetic resin materials were also used plastic products and evaluate their strength. In addition, the change in production was assessed.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.513-528
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• 2020

This paper presents the results of an experimental study on the residual behavior of reinforced recycled aggregate concrete (RRAC) beam-columns after exposure to elevated temperatures. Two parameters were considered in this test: (a) recycled coarse aggregate (RCA) replacement percentages (i.e. 0, 30, 50, 70 and 100%); (b) high temperatures (i.e. 20, 200, 400, 600, and 800℃). A total of 25 RRAC short columns and 32 RRAC beams were conducted and subjected to different high temperatures for 1 h. After cooling down to ambient temperature, the following basic physical and mechanical properties were then tested and discussed: (a) surface change and mass loss ratio; (b) strength of recycled aggregate concrete (RAC) and steel subjected to elevated temperatures; (c) bearing capacity of beam-columns; (d) load-deformation curve. According to the test results, the law of performance degradation of RRAC beam-columns after exposure to high temperatures is analyzed. Finally, introducing the influence coefficient of RCA replacement percentage and high temperatures, respectively, to correct the calculation formulas of bearing capacity of beam-columns in Chinese Standard, and then the residual bearing capacity of RRAC beam-columns subjected elevated temperatures is calculated according to the modified formulas, the calculated results are in good agreement with the experimental results.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.2 s.110
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• pp.21-29
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• 2005

Increase in the utilization rate of recycled paper has significantly increased the problem associated with stickies. Despite the effort to eliminate contaminants from recycled furnishes, stickies are still the most serious obstacle in using recycled paper. The amount of micro stickies that are too small to be eliminated by screening, tends to increase significantly as the closure level of white water system is increased and the quality of raw material deteriorates. To establish a process efficient in removing micro stickies is strongly required. In this study, the surface characteristic of micro stickies was investigated with contact angle measurement. Surface energies of MCC, PSA film and model micro stickies were 53.37 mN/m, 29.75mN/m, and 29.63mN/m, respectively. This indicates that the surface characteristic of MMS is very similar to PSA. Thus, solvent coating of PSA and evaporation of the solvent provided excellent model micro stickies for flotation experiment.

• Ceramist
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• v.14 no.2
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• pp.7-14
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• 2011

This paper has investigated physicochemical properties and conventional and environmental-friendly treatment methods of paper mill sludge to emphasize the importance and necessity of the sludge recycling. The paper mill sludge generally shows high contents of calcium and water, and is mostly discharged by landfill after incineration process rather than being recycled due to technical or economical problems. In recent years, however, several possible methods for recycling the paper mill sludge have been suggested for its sustainable process as follows; compost, raw material for the construction and paper industry, new energy source for reducing fossil fuel use and raw material of activated carbon for treating paper mill wastewater. Thus the authors suggest that practical recycling technologies of the paper mill sludge must be developed for substantiality in the paper industry through comprehending physicochemical compositions and generation status of the sludge and actively performing various related studies. Furthermore, this investigation could be used as preliminary information for the study on recycled paper development using paper mill sludge incineration ash.

• Advances in concrete construction
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• v.6 no.2
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• pp.103-121
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• 2018

This paper reports the effects of coarse and fine recycled concrete aggregates (RCA) on fresh and hardened properties of self-compacting concrete (SCC) containing ground granulated blast-furnace slag (GGBFS) as cement replacement. For this purpose, three SCC mixes groups, were produced at a constant water to binder ratio of 0.38. Both fine and coarse recycled aggregates were used as natural aggregates (NA) replacement at different substitution levels of 0%, 25%, 50%, 75% and 100% by volume for each mix group. Each group, included 0, 15% or 30% GGBFS as Portland cement replacement by weight. The SCC properties investigated were self-compactability parameters (i.e., slump flow, T500 time, V-funnel flow time, L-box passing ability and sieve stability), compressive strength, capillary water absorption and water penetration depth. The results show that the combined use of RCA with GGBFS had a significant effect on fresh and hardened SCC mixes. The addition of both fine and coarse recycled aggregates as a substitution up to 50% of natural aggregates enhance the workability of SCC mixes, whereas the addition from 50 to 100% decreases the workability, whatever the slag content used as cement replacement. An enhancement of workability of SCC mixes with recycled aggregates was noticed as increasing GGBFS from 0 to 30%. RCA content of 25% to 50% as NA replacement and cement replacement of 15% GGBFS seems to be the optimum level to produce satisfactory SCC without any bleeding or segregation. Furthermore, the addition of slag to recycled concrete aggregates of SCC mixes reduces strength losses at the long term (56 and 90 days). However, a decrease in the capillary water absorption and water permeability depth was noticed, when using RCA mixes with slag.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.1
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• pp.68-73
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• 2002

High temperature during sprout emergence period of potato (Solanum tuberosum L.) is a major limitation to the yield of fall-grown potato in Korea. To explore the possibility of improving the yield of fall-grown potato through recycled paper mulching, the changes of soil environment and the growth and yield of potato cv. Daeji as affected by three mulching treatments of non-mulched control, recycled paper mulching (RPM), and black polyethylene film-mulching (BPFM) were examined over two fall seasons at Suwon, Korea. The mulching materials were a recycled mulch paper with 110 g/$m^2$ and a thickness of 0.1 mm, which was manufactured from old corrugated containers for this experiment and a commercial black polyethylene film with a thickness of 0.01mm. On an average throughout the growing period, the soil temperature with RPM at the 5-cm depth was lower by 0.4-1.1$^{\circ}C$ than that of the control. The maximum temperature during daytime in RPM was lowered by approximately 1 to 5$^{\circ}C$ according to the weather condition during emergence period, the difference being great on a fine day. The soil temperature with BPFM was much higher than the control. The effect of the mulching treatments diminished as the canopy became developed. The mulching treatments were more advantageous than the control in the conservation of soil water. Moreover, RPM and BPFM efficiently suppressed the occurrence of weeds until the potato harvest. RPM improved the emergence significantly due to lower soil temperature, whereas BPFM showed much poorer emergence than the control. Growth after emergence and yield were significantly higher in RPM than in the control and BPFM. It was concluded that the significantly improved yield in RPM compared to that in the control was mainly due to the improvement of the sprout emergence and tuber growth accompanied by lower soil temperature and better conservation of soil water.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.3
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• pp.28-36
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• 2014

The kind and the mixing ratio of recovered papers would affect the quality of final recycled paper. In this study, effects of the mixing ratio of various domestic recycled papers (old news print (ONP), old corrugated container (OCC) and coated paper (CP)) on variations in physical properties of paper and its productivity were investigated. When the mixing ratio of CP grade increased, the freeness (CSF) of recycled pulp was increased while paper strength and white water turbidity was decreased. Paper strength was decreased as the percentage of OCC was higher than ONP. When ONP was mixed with OCC, no adverse effect was observed except the increased drainage resistance. It is expected that these results could be utilized as fundamental data to establish regulations for the recovered paper grades according to mixing ratios of different kinds of them.

• Textile Coloration and Finishing
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• v.29 no.4
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• pp.239-246
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• 2017

Recently fiber-reinforced thermoplastic composites have attracted great interest from industry and study because they offer unique properties such as high strength, modulus, impact resistance, corrosion resistance, and damping reduction which are difficult to obtain in single-component materials. The demand for plastics is steadily increasing not only in household goods, packaging materials, but also in high-performance engineering plastic and recycling. As a result, the technology of recycling plastic is also attracting attention. In particular, many paper have studied recycling systems based on recycled thermoplastics. In this paper, properties of Glass Fiber Reinforced Thermoplastic(GFRTP) materials were evaluated using recycled PET for injection molding bicycle frame. The effect on thermal and mechanical properties of recycled PET reinforced glass chop fiber according to fiber cross section and fiber content ratio were studied. And it was compared void volume and torque energy by glass fiber cross section, which is round section and flat section. Mechanical characteristics of resulting in GF/rPET has been increased by increasing fiber contents, than above a certain level did not longer increased. And mechanical properties of flat glass fiber reinforced rPET with low void volume were most excellent.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.19-26
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• 2014

In-situ $CaCO_3$ formation on recycled wood pulp was studied to improve optical property and filler attachment to the fiber furnish in papermaking. We tried to attach calcium oxide (CaO) to the recycled fibers, old newspaper (ONP) in this case, by using selected polymers before in-situ $CaCO_3$ formation reaction on fibers, and then, $CO_2$ was injected to the furnish until all the CaO on fiber surfaces was consumed. It was found that the attachment of newly formed $CaCO_3$ to recycled fibers became stronger by attaching CaO to the fibers before in-situ $CaCO_3$ formation reaction. It was expected that the polymers used for the attachment of calcium source to the fiber furnishes helped to keep the newly formed $CaCO_3$ strongly attached to the fiber surface as well as to retain the impurities associated with calcium source and recycled fibers, if any. In-situ $CaCO_3$ formation gave higher brightness and much less ERIC value in ONP sheet than the case when the equivalent amount of GCC was added to the furnish.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.193-203
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• 2011

The purpose of this study, looking to which the recycled fine aggregates from waste concrete have a lot of problems as a material for structure purpose, is applying the recycled fine aggregate to Self-Compacting Concrete(In the reminder of this paper, it often referred to as SCC) by using the characteristic which the powder containing the recycled fine aggregates can increase strength and liquidity. In this study, that is, the recycled fine aggregate powder is appropriate for developing high strength(over 40 MPa) and liquidity(JSCE 2 grade), the characteristic of the SCC and it was increased the ratio of mixing the recycled fine aggregates emerging from waste concrete and the normal fine aggregates by 25%, making differential in total 5 levels and applied to SCC. After all, this study was reviewed the physical properties of the fresh concrete, analyzed the mechanical properties and durability of the hardening concrete and tried to ensure the possibility of utilizing the recycled fine aggregates as a material for SCC. As a result, this study reached a conclusion that among the 5-level replacement ratios of the physical, mechanical analysis and the durability characteristics, the normal fine aggregates could be applied up to a replacement ratio of 50% more than the recycled fine aggregates and resulted in a deterioration in performance the replacement ratio larger than 50%. It is judged that the applicability of the real structures should be followed up in order to check the possibility of applying the recycled fine aggregates to real life.