• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.05a
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• pp.227-234
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• 2002

With the increasing environmental consideration and stricter regulations, gasification of waste is considered to be more attractive technology than conventional incineration for energy recovery as well as material recycling. The experiment for combustible waste mixed with plastic and cellulosic materials was performed in the fixed bed gasifier to investigate the gasification behavior with the operating conditions. Waste pelletized with a diameter of 2~3cm and 5cm of length was gasified at the temperature range of 1100~145$0^{\circ}C$. It was shown that the composition of H$_2$ was in the range of 30~40% and CO 15~30% depending upon oxygen/waste ratio. Casification of waste due to thermoplastic property from mixed plastic melting and thermal cracking shows a prominent difference from that of coal or coke. It was desirable to maintain the top temperature up to foot to ensure the mass transfer and uniform reaction through the packed bed. As the bed height was increased, the formation of H$_2$ and CO was increased whilst $CO_2$ decreased by the char-$CO_2$ reaction and plastic cracking. From the experimental results, the cold gas efficiency was around 61% and heating values of product gases were in the range of 2800~3200㎉/Nm3.

• Journal of ILASS-Korea
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• v.7 no.2
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• pp.7-15
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• 2002

A particle flow visualization, electrostatic charging measurement and separation of triboelectrically charged particles in the external electric field by a fluidized bed tribocharger are conducted for the removal of PVC particles from mixed waste plastics. The laboratory-scale triboelectrostatic separation system consists of the fluidized bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges respectively due to the difference of triboelectric charging series between particles and particles in the fluidized bed tribocharger, and can be separated by passing them through an external electric field. To visualize these charged particles, He-Ne laser is used with cylindrical lenses to generate a sheet beam. In the charging measurement, the particle motion analysis system (PMAS), capable of determining particle velocity and diameter. is used to non-intrusively measure particle behavior in high strength electric field. The average charge-to-mass ratios of PVC and PET particles are $1.4\;and\;1.2{\mu}C/kg$, respectively. The highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials for a single-stage processing. The triboelectrostatic separation system using the fluidized tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.

• Resources Recycling
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• v.23 no.4
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• pp.30-36
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• 2014

300,000 tons of waste tires are annually being produced with development of the automotive industry in Korea. Landfill and incineration treatment system are causing the economic problem through secondary environmental pollution and waste. Therefore, as one of the ways to take advantage of this, Thermo-Plastic Vulcanized (TPV) composite was prepared by the ground waste tire and plastic powders. The waste tire powder was gained by mechanical fracturing through crushers. The waste tire powder was ground by a shear crushing method and a 2-stage disk mill method instead of cutting crushing one. The waste tire powder of 50 mesh was mixed with Polypropylene(PP) in various proportions. TPVs were prepared by an extrusion, and tensile and impact tests were performed. In addition, the same experiments were repeated in 40, 80, 140 mesh conditions in order to observe size effect of waste tire powders.

• International Journal of Advanced Culture Technology
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• v.9 no.3
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• pp.305-314
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• 2021

Currently, due to COVID-19, household waste has a lot of impact on the environment due to packaging of food delivery. In this paper, we design and implement Faster-RCNN, SSD, and YOLOv4 models for municipal waste detection and classification. The data set explores two types of plastics, which account for a large proportion of household waste, and the types of aluminum cans. To classify the plastic type and the aluminum can type, 1,083 aluminum can types and 1,003 plastic types were studied. In addition, in order to increase the accuracy, we compare and evaluate the loss value and the accuracy value for the detection of municipal waste classification using Faster-RCNN, SDD, and YoloV4 three models. As a final result of this paper, the average precision value of the SSD model is 99.99%, the average precision value of plastics is 97.65%, and the mAP value is 99.78%, which is the best result.

• Resources Recycling
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• v.23 no.4
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• pp.3-11
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• 2014

Large scale generation of plastic waste has generated considerable interest it seeking innovative solutions to waste recycling and reuse. Plastic solid waste(PSW) treatment and recycling processes could be allocated to four major categories, re-extrusion(primary), mechanical recycling(secondary), chemical recycling(tertiary) and energy recovery(quaternary). This review considers the various aspects of the PSW recycling such as recycling methods of PSW, special problems about some proposed process, separation techniques, and recycling of mixed PSW.

• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1485-1495
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• 2003

We investigate the triboelectrostatic separation of polyvinylchloride (PVC) from mixed plastics in the laboratory scale triboelectrostatic separation system. The flow and electric fields in the precipitator are obtained from the numerical solution of finite volume method. Using these flow and electric fields, we solved the particle motion equation considering the inertia, drag, gravity and electrostatic forces acted on the particles. The particle trajectories are obtained using a Lagrangian method as a function of different important variables such as Reynolds number, Stokes number, electrostatic force, electric charge and electric field distribution, inclined angle of plane electrodes, particle rebounding, particle charge decay rate after impact on the electrode surface, etc., in order to determine the optimal design conditions. The present predicted results for the cumulative yield represent well the experimental ones.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.65-71
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• 2006

Flame retardancy and mechanical properties of polyolefinic mixed waste plastics/filler composites were investigated by using inorganic flame retardant(magnesium hydroxide) and PUB(polyurethane block) powder generated from cryogenic insulation process. All composites were obtained by extrusion and after compression molding. The effect of PUB powder on the properties of the composites was studied by tensile and izod impact test, morphology studies and flammability as LOI and UL94 vertical burning test and smoke density. The objective of this work is to obtain good mechanical properties from recycled PP composites with $Mg(OH)_{2}/PUB$ powder as fillers and optimum cost-performance balance, in addition to flame retardant characteristics.

• Resources Recycling
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• v.16 no.4
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• pp.47-60
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• 2007

Plastic supply and recycling are increasingly becoming matters of social concern. In our country, Extended Producer Responsibility(EPR) system has been adopted in 2003 to expand recycle and reuse of waste resources at producer side, and due to expansion of the EPR system, amount of the mixed plastic waste generation has been drastically increased. Plastic-plastic separation is most fundamental technique to achieve effective plastic recycling. This paper reviews recent developments in plastic-plastic separation techniques and describe future tasks. The mechanisms of each separation which contain gravity separation, electrostatic separation, flotation, and separation of automotive shredder residue are described, and commercial scale and lab-scale results are introduced.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.3
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• pp.48-52
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• 2008

Waste paper plastic composites were prepared with old newspaper and old corrugated containers and mixed office waste and those properties were evaluated. The results were summarized as fellows. 1. The strength properties like as tensile and Young's modulus reveled most high level in MOW composite. 2. The coagulation of fibers in paper particle should interrupt equal dispersion of polymer and paper particle. 3. The micrograph of the surface of composites showed the most high dispersion in ONP composite.

• Journal of Environmental Health Sciences
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• v.13 no.2
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• pp.51-63
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• 1987

We identified pyrolysis condition, effect of catalyzer and pyrolysis mechanism through contact decomposed method by adding Bentonite in waste plastic of hospital solid waste. The result from this study were summarized as the followings: 1. The optimum fuel oil were obtained when hospital wasted plastic (P.P) and Bentonite were mixed in the ratio of 30:1. 2. Maximum absorption wave of hospital wasted plastic (P.P) appeared at 2900cm$^{-1}$, 1480cm$^{-1}$, 1360cm$^{-1}$ and 1180 cm$^{-1}$ by FT-IR and the plastics were identified and confirmed. 3. Reaction temperature of hospital wasted plastic started at 360$\circ$C, proceed rapidly at 437.5$\circ$C and finished at 481$\circ$C. The residue was 0.729%. When bentonire was added started at 318$\circ$C, proceed rapidly at 399.5$\circ$C and finished at 449.3$\circ$C, the residue being 4.23%. 4. Pyrolysis products of hospital wasted plastic were about 90 kinds. The Main components were 2-Heptene-3-ethyl-4-trimethyl (27.4%), 1-Heptene-2-isobutyl-6-methyl (8.6%) and 1-Heptene decene (7.7%). There was little component difference at different temperature. This is the result from stability of decomposition product. 5. Pyrolysis efficiency increased by the addition Bentonire. 6. Some of the Environmental and Sanitary problems could be solved by the pyrolysis of hospital wasted plastic and the decomposed products were to be used as fuel oil.