• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.182-188
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• 2008

The compounds of recycled polyethylene(PE) and fly-ashes were prepared. Polymers used were sorted PE from mixed plastics of household waste and Low Density Polyethylene(LDPE) and Linear Low Density Polyethylene(LLDPE) recycled from the scrap of packaging film plants. Fly-ashes were from the power plant and from the household waste incinerator. The tensile strength of recycled LDPE and LLDPE compounds decreased and the flexural modulus increased with greater amount of the power plant fly-ash. Anthracite fly-ash gave rise to slightly higher tensile and flexural strength of the LLDPE mixtures than bituminous coal fly-ash presumably due to higher content of unburned carbon. The incinerator fly-ash introduced to household waste PE enhanced both tensile strength and flexural modulus of the compounds. When LDPE and household waste PE were used together, the synergistic effect of incinerator fly-ash to household waste PE was offset by reduced crystallization of LDPE due to the filler particle. The compounds of household waste PE and incinerator fly-ash might be applied to structural materials for such as sewage pipe, which reduces the waste treatment cost and conserve the environment and resources.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.693-699
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• 2011

Internal combustion engines running on syngas, which can be obtained from biomass or organic wastes, are expected to be one of the suitable alternatives for power generation, because they are environment-friendly and do not contribute to the depletion of fossil fuels. However, syngas has variable compositions and a lower heating value than pure natural gas, owing to which the combustion conditions need to be adjusted in order to achieve stable combustion. In this study, a gas that has the same characteristics as syngas, such as low heating value (LHV), was produced by mixing $N_2$ with compressed natural gas (CNG). In addition, this study investigates the combustion characteristics of syngas when it is mixed with hydrogen in a ratio ranging from 10% to 30% with a constant LHV of total gas.

• Analytical Science and Technology
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• v.15 no.1
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• pp.20-25
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• 2002

An accurate and simple analytical technique for $^{89}Sr$ and $^{90}Sr$, overcoming the demerits of the conventional method, has been developed with extraction chromatography and liquid scintillation counting. The Sr fraction was separated from hindrance elements with oxalate coprecipitation or cation exchange resin and purified with Sr-Spec column. With liquid scintillation counter, $^{89}Sr$ was measured by Cerenkov radiation method, and $^{90}Sr$ was measured by spectrum unfolding method. The developed radioactive strontium separation method was validated by application to the IAEA-reference material (IAEA-375, Soil) and radioactive waste samples.

• Environmental Analysis Health and Toxicology
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• v.25 no.1
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• pp.11-18
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• 2010

Toxicity assessment of ocean dumping wastes (dye waste, urban sewage, food waste) were examined in the fertilization and embryo development rates of the Sea Urchin, Hemicentrotus pulcherrimus. Spawning was induced by injecting 1 mL of 0.5 M KCl into coelomic cavity. Males released white or cream-colored sperms and females released yellow or orange-colored eggs. Experiments were began within 30 min the collection of both gametes. The fertilization and embryo development rates test were performed for 10 min and 64 h after fertilization, respectively. The fertilization and embryo development rates in the control condition (not including ocean dumping wastes sludge elutriate) were greater than 90%, but suddenly decreased with increasing of ocean dumping waste sludge elutriate concentrations. The fertilization and normal embryogenesis rates were significantly inhibited in all waste sludge elutriate from dye waste ($EC_{50}$=4.37; $EC_{50}$=1.76), urban sewage ($EC_{50}$=5.79; $EC_{50}$=2.00) and food waste ($EC_{50}$=7.68; $EC_{50}$=2.16), respectively. The NOEC (<3.13) and LOEC (3.13) of fertiliztion and normal embryogenesis rates very similar in all waste sludge elutriate. These results suggest that biological assay using the fertilization and embryo development rates of H. pulcherrimus are very useful test method for the ecological toxicity assessment of ocean dumping wastes.

• Analytical Science and Technology
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• v.11 no.5
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• pp.394-399
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• 1998

This study was carried out to characterize the chemical composition and leaching properties of heavy metals in coal fly ash, which was generated from Korean electrical power utilities in several million tons per year. Comparion with respect to the leachability of heavy metals between the Korea standard leaching test (KSLT) and the American Environment Protection Agency (EPA) method 1311 (TCLP: Toxicity Chracteristic Leaching Procedure) was performed. The concentration of Ag, As, Ba, Cd, Cr, Cu, Pb, Se, Hg in the leacheate was determined by ICP-MS. The analytical result showed a significant difference of the leachability according to the characteristics of the leaching solution except Se, suggesting the necessity of improvement in the leaching test method that is currently implemented in Korea.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.300-303
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• 2010

Environmental issues on the waste emission and its treatment are of great interest in these days. In order to resolve the pollution problems, recycling the waste materials is generally recommended. Especially, emission of waste acids in designated sources is increasing every year. In this study, we focused on the effective recycling of the waste acids rather than treatments. Management systems of the waste acids are not systematically designed, and the quality of the waste regulation on the recycling product is unclear in domestic and foreign countries. We surveyed the present conditions on domestic waste emission and recycling of waste acids. For the final analysis of the recycling products, iron chloride, iron sulfate, copper cyanide, copper oxides, and cement copper are selected as candidates. We expect that this article would help establishing the systematic management system on treating the waste acid materials.

• Resources Recycling
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• v.24 no.5
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• pp.22-32
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• 2015

This study aims to discuss the concept of upcycling as it applies to diaper recycling. Upcycling is the process of converting waste materials into new products of better quality. Through benchmarking of upcycling examples, useless objects can be transformed into valuable materials. However, current upcycling examples determine value creation related to qualitative elements, so that it is difficult to establish any quantitative strategy of upcycled products. Therefore, this study expands a B2B (Business to business) product for improving market availability and establishes a direction using both recovered pulp and mixed plastic at the same time. As a result, the upcycling method for recovered pulp and mixed plastics, is the application of a cellulose insulator. Within the near future, the high quality insulator market will grow more than three times. An upcycling strategy targeting the high quality insulator market needs to be established.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1059-1066
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• 2009

Recently, the amount of thermosetting plastic wastes has increased with the production of reinforced plastic composites and causes serious environmental problems. The epoxy resins, one of the versatile thermosetting plastics with excellent properties, cannot be melted down and remolded as what is done in the thermoplastic industry. In this research, a series of experiments that decompose epoxy resin and recover carbon fibers from carbon fiber reinforced epoxy composites applied to railway vehicles was performed. We experimentally examined various decomposition processes and compared their decomposition efficiencies and mechanical property of recovered carbon fibers. For the prevention of tangle of recovered carbon fibers, each composites specimen was fixed with a Teflon supporter and no mechanical mixing was applied. Decomposition products were analyzed by scanning electron microscope (SEM), gas chromatography mass spectrometer (GC-MS), and universal testing machine (UTM). Carbon fibers could be completely recovered from decomposition process using nitric acid aqueous solution, liquid-phase thermal cracking and pyrolysis. The tensile strength losses of the recovered carbon fibers were less than 4%.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.15-19
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• 2012

Wood wastes could be renewable resources by recycling as particleboard manufacturing or energy production. Particle board is the most common item of wood waste recycling and energy production from wood wastes has highlighted for energy recovery to reduce greenhouse gas generation in recent years. The aim of this study was to evaluate the environmental benefits of the processes for particle board manufacturing and energy production. The functional unit was one ton of wood wastes and the environmental impact was analyzed by life cycle assessment methodology. The result was that 112kg of carbon dioxide equivalent was produced from particle board manufacturing process and 382kg of carbon dioxide equivalent was produced from combined heat and power generation process. The concept of temporary biomass carbon storage was to applied to this study.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.761-764
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• 2008

Most of ready-mixed concrete plants have the problem of construction waste sludge, which pollutes environment and causes economic loss due to the discard and increasing the cost of concrete. Thus, a recycling of the cement sludge has been strongly desired as one of their solution. This research is to the study on the recycling of the cement sludge, especially the study on the hydration control by the sodium gluconate as a set-retarder. The set-retarder can delay the hydration of the cement included in the sludge water, so that the sludge water can be substituted with some of new cement without the property of the cement. And it invests the effect of the sodium gluconate to the hydration of the cement in suspension. The degree of hydration of cement may be controlled by adding the sodium gliconate. The hydration delay time is observed that depends on the concentration of residual sodium gloconate, not how long the cement has been hydrated before the addition of the sodium gluconate.