• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.45-54
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• 2012

Various geosynthetics are widely applied to civil structures and waste landfill site for reinforcement and water resistance. The use of geosynthetics inevitably involves the coupled behaviors of different materials which include large displacement and strain-softening behaviors, etc. In this study, the effect of chemical element in the leachate on the interface shear strength under the cyclic loading condition was analyzed. The Multi-purpose Interface Apparatus (M-PIA) has been modified and cyclic direct shear tests have been performed. The submerging period of each specimen is 200 days. Additionally, the Field-Emission Scanning Electronic Microscopy (FIB) analysis has been also performed to induce the reason of the variation of disturbance function and verify the hypothesis on the decay-proof ability of geosynthetics. Consequently, the charateristics of chemical degradation of geosynthetic-soil interface are verified and the variation of the disturbance function is mainly caused by the different type of soil mineral decay, based on the FIB results.

• International Commerce and Information Review
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• v.16 no.4
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• pp.171-190
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• 2014

A short consumption cycle caused by the technological development and the diversification of customer lead to both the dynamic growth of the industry and the waste recycling issue at the same time. Including Korea, the situation is particularly worrisome in some countries, such as India and China, where acute environmental hazards have resulted from a combination of a lack of recycling centers' capacity and the domination of a large backyard recycling sector. A study about to maximize the current recycling center efficiency with minimal changes is required. In this study, we suggest the optimal location selection method for the recycling center based on the well-known reverse logistics cost minimization model. An actual recycling data about a specific electronic equipment and region in Korea are used for the verification of the method suggested.

• Resources Recycling
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• v.16 no.2 s.76
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• pp.63-76
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• 2007

Typical examples as unrecycled materials in Korea were Zinc from the electric arc furnace dust (EAF Dust), and Moiybdenium and Vanadium from the desulfurizing spent catalyst of petrochemical industries. In the otherwise, though recovery of valuable metals from the waste electronic scrap such as printed circuit boards (PCBs) and platinum group metals (PGM) from the waste automobile catalyst have been interesting issues, it is difficult to collect the exact informations or statistics on their material flow system. In this article, The current domestic research trends for unrecycled or less recycled materials have been reviewed, and material flow and recycling technologies on the desulfurizing spent catalyst were surveyed.

• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.339-345
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• 2017

Carbonaceous adsorbent (CA-WTP) was prepared by heat treatment at $400^{\circ}C$ for 2 h in N2 atmosphere using waste tire powder (WTP). WTP and CA-WTP were first characterized by thermo-gravimetric analysis (TGA), energy dispersive X-ray spectrometer (EDS), scanning electron microscopy (SEM), specific surface area analysis (BET) and FT-IR spectroscopy. Then, they were tested as adsorbents for removal of Cd in water. CA-WTP exhibited much higher specific surface area and total pore volume than WTP itself and showed higher adsorption capacity for Cd. Equilibrium data of adsorption were analyzed using Freundlich and Langmuir isotherm models. It was seen that both Freundlich and Langmuir isotherms have correlation coefficient $R^2$ value larger than 0.95. The results of studies indicate that CA-WTP developed from WTP by heat treatment could be used as efficient adsorbent for the removal Cd from water.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.660-669
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• 2018

Domestic automotive shredder residue (ASR) recycling facilities must comply with 60% of the energy recovery criteria calculated by the waste control act, based on resource circulation of electrical and electronic equipment and vehicles. The method of calculating energy recovery criteria was newly enacted on November 6, 2017, and it has been judged that it is necessary to consider applicability. In this study, the energy recovery efficiency of 7 units was calculated by past and present calculation methods. Furthermore, this study attempts to find applicability and a method of increasing the energy recovery efficiency by taking advantage of available potentials. An analysis of the calculation results showed that the average values calculated by past methods, present methods, and the method that includes available potentials are 76.35%, 70.68%, and 78.24%, respectively. Therefore, the new calculation method for energy recovery efficiency is also applicable to domestic automotive shredder residue recycling facilities.

• Resources Recycling
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• v.23 no.2
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• pp.61-70
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• 2014

LCD televisions and monitors use cold cathode fluorescence lamps (CCFLs) to illuminate the screen. Most CCFLs contain mercury and they have to be carefully handled at the end of their lives as per minimum treatment standards under the Waste Electrical and Electronic Equipment (WEEE) and Restriction of Hazardous Substances (RoHS) directives. CCFLs were carefully separated from mold frames of waste LCD units for primary decontamination of mercury/fluorescent compound mixture using CCFL decontamination system designed and fabricated in the present research. Residual mercury was further removed by employing a pyro-process, where crushed CCFL tubes transferred from primary decontamination process were subject to heat treatment at $550^{\circ}C$ in a box furnace: more than 99% of mercury was removable from waste CCFLs.

• Resources Recycling
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• v.25 no.3
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• pp.11-19
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• 2016

A fundamental study to recycle a Si-Sludge and waste copper nitrate solution acid solution generated by domestic electronic industries was carried out. The waste copper nitrate solution was used as the lixiviant to leach the metals like Cu, Ca, Fe, etc. from the sludge leaving Si in the residues. The effect of reaction temperature, time and pup density on the metals leaching from the sludge was investigated. To enhance the extractability of Fe, the effect of HCl, $HNO_3$ and $H_2O_2$ introduced additionally during the leaching was also examined. Considering the leaching efficiency of Fe along with Cu, the leaching conditions comprising of 200 ~ 225 g/L pulp density and $90^{\circ}C$ temperature for 30 min were optimized. Under this condition, 98.27 ~ 99.17% Cu could be dissolved in the leach liquor with the obtained purity of Si in the residues as 98.69 ~ 98.86 %. The study revealed that the leaching of Cu contained in the Si-Sludge with the waste copper nitrate solution is a plausible approach by which the obtained leach liquor can further be treated suitably to recover Cu as the high pure value-added products.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1315-1323
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• 2018

We studied the carbonization due to the annealing condition of waste coffee powder for application as an active anode material for lithium-ion batteries (LIBs). The coffee powder used as an active anode material for LIBs was obtained from coffee beans, not from a coffee shells. The waste coffee powder was dried in air and heat-treated in an $Ar/H_2$ atmosphere to obtain a pore-forming activated carbon powder. The specific capacity of the sample annealed at $700^{\circ}C$ was still 303 mAh/g after 1000 cycles at a current density of 1000 mA/g and with a coulombic efficiency of over 99.5%. The number of pores and the pore size of the waste coffee powder were increased due to chemical treatment with KOH, which had the some effect as an increased specific surface area. The waste coffee powder is considered to be a very promising active anode material because of both its excellent electrochemical properties due to enhanced carrier conduction and its being a cost effective resource for use in LIBs.

• Resources Recycling
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• v.31 no.6
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• pp.81-91
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• 2022

The use of lithium-ion batteries increases significantly with the rapid spread of electronic devices and electric vehicle and thereby an increase in the amount of waste batteries is expected in the near future. Therefore, studies are continuously being conducted to recover various resources of cathode active material (Ni, Co, Mn, Li) from waste battery. In order to recover the cathode active material, black mass is generally recovered from waste battery. The general process of recovering black mass is a waste battery collection - discharge - dismantling - crushing - classification process. This study focus on the crushing/classification process among the processes. Specifically, the particle size distribution of various samples at each crushing/classification step were evaluated, and the particle shape of each particle fraction was analyzed with a microscope and SEM (Scanning Electron Microscopy)-EDS(Energy Dispersive Spectrometer). As a result, among the black mass particle, fine particle less than 74 ㎛ was the mixture of cathode and anode active material which are properly liberated from the current metals. However, coarse particle larger than 100 ㎛ was present in a form in which the current metal and active material were combined. In addition, this study developed a PBM(Population Balance Model) system that can simulate two-species mixture sample with two different crushing properties. Using developed model, the breakage parameters of two species was derived and predictive performance of breakage distribution was verified.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1131-1138
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• 2015

As the size of the internet market grows rapidly, the number of IPv4 addresses available is being exhausted, while transition to IPv6 is being delayed. As the best alternative solution, Network Address Translation(NAT) scheme is being used. It connects the public internet network with the private internet network in order to reduce the waste of IPv4 addresses space. The purpose of this paper is to study the effective example of network based on common virtual network using Packet Tracer with topology designed rather than usual theoretical approach in Dynamic NAT and PAT, which allows more efficient use of address space.