• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.265-273
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• 2019

This research aims at developing human resources who will serve as flexible mediators in the future national or cultural conflict situations. The primary learning contents approach the class by selecting the upcycling design activities, in which the students recognize the problem of waste that is for all and study representative characteristics and backgrounds of each culture. The classes were held centering around the student members of GunpoYMCA, and the culturally characteristic materials were made through upcycling design. The activities included making giraffes in Africa with plastic bottles, Mongolian tents with wooden posts, snow globes with sauce pots, patchworks and rugs with shirts and textiles, and garlands with banners, which helped students learn the new term upcycling as well as get interested in the environmental problems. Also, they could understand other cultures by creating materials that represent each culture and studying their origins and historical backgrounds. In conclusion, this research offers value by developing abilities to cope with not only conflicts between cultures but confrontations between nations in the larger scope.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.1-9
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• 2023

The unconfined compression strength (UCS) of soils is commonly used either before or during the construction of geo-structures. In the pre-design stage, UCS as a mechanical property is obtained through a laboratory test that requires cumbersome procedures and high costs from in-situ sampling and sample preparation. As an alternative way, the empirical model established from limited testing cases is used to economically estimate the UCS. However, many parameters affecting the 1D soil compression response hinder employing the traditional statistical analysis. In this study, gene expression programming (GEP) is adopted to develop a prediction model of UCS with common affecting soil properties. A total of 79 undisturbed soil samples are collected, of which 54 samples are utilized for the generation of a predictive model and 25 samples are used to validate the proposed model. Experimental studies are conducted to measure the unconfined compression strength and basic soil index properties. A performance assessment of the prediction model is carried out using statistical checks including the correlation coefficient (R), the root mean square error (RMSE), the mean absolute error (MAE), the relatively squared error (RSE), and external criteria checks. The prediction model has achieved excellent accuracy with values of R, RMSE, MAE, and RSE of 0.98, 10.01, 7.94, and 0.03, respectively for the training data and 0.92, 19.82, 14.56, and 0.15, respectively for the testing data. From the sensitivity analysis and parametric study, the liquid limit and fine content are found to be the most sensitive parameters whereas the sand content is the least critical parameter.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.139-144
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• 2023

Stone papers made of inorganic filler and plastic polymer do not use pulp, which is the main raw material of existing papers, so they contribute to the preservation of nature and can be used as more eco-friendly materials when they have biodegradability. Since most stone papers are manufactured by hot extrusion, the amount of ceramic fillers and related physical properties are limited to control manufacturing workability. In this study, the stone paper composition was prepared in a liquid form using solvents, so that there was little limitation on the amount of ceramic filler added and it was also easy to add additives to control biodegradability. They were fabricated from eco-friendly raw materials using waste oyster shells as an inorganic filler and (recyclable) PVC materials as an organic binder. After making a solution using common solvents for PVC, inorganic filler and cellulose to impart biodegradability were mixed and processed into sheets to prepare solvent-based stone papers, and their paper properties were evaluated.

• Applied Chemistry for Engineering
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• v.35 no.4
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• pp.273-283
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• 2024

As the adverse environmental impacts due to plastic waste become more severe, there is an increasing demand for developing a sustainable ecosystem using biodegradable polymers. Biodegradable polymers are those that can be biochemically decomposed through the enzymatic activity of microorganisms. Currently, a variety of biodegradable polymers with varying properties is being investigated. In particular, polymer blends with an aim to control the biodegradation rate and mechanical properties are under active research. The biodegradable polymer industry, which has not yet reached economies of scale, does not have a cost advantage compared to petroleum-derived polymers. To overcome this challenge, there is an urgent need to expand its application fields to various high-value industries (separators, electronic materials, and medical fields). This review summarizes the current state-of-the-art biodegradable polymers, polymer blends, and recent research trends in new niche applications.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.83-92
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• 2022

The amount of the plastic waste has been increasing according to global demand for plastic. Microplastics are the most hazardous among all plastic pollutants due to their toxicity and unknown physicochemical properties. This study investigates the optimal methodology that can be applied to sewage samples for detecting microplastics before discussing reducing microplastics in MWTPs. In this study, the effect of different pretreatment methods while detecting microplastic analysis of MWTP influent samples was investigated; the samples were collected from the J sewage treatment plant. There are many pretreatment methods but two of them are widely used: Fenton digestion and hydrogen peroxide oxidation. Although there are many pretreatment methods that can be applied to investigate microplastics, the most widely used methods for sewage treatment plant samples are Fenton digestion and H₂O₂ oxidation. For each pretreatment method, there were factors that could cause an error in the measurement. To overcome this, in the case of the Fenton digestion pretreatment, it is recommended to proceed with the analysis by filtration instead of the density separation method. In the case of the H₂O₂ oxidation method, the process of washing with distilled water after the reaction is recommended. As a result of the analysis, the concentration of microplastics was measured to be 2.75ea/L for the sample using the H₂O₂ oxidation method and 3.2ea/L for the sample using the Fenton oxidation method, and most of them were present in the form of fibers. In addition, it is difficult to guarantee the reliability of measurement results from quantitative analysis performed via microscope with eyes. A calibration curve was created for prove the reliability. A total of three calibration curves were drawn, and as a result of analysis of the calibration curves, all R² values were more than 0.9. This ensures high reliability for quantitative analysis. The qualitative analysis could determine the series of microplastics flowing into the MWTP, but could not confirm the chemical composition of each microplastic. This study can be used to confirm the chemical composition of microplastics introduced into MWTP in the future research.

• Journal of the Korean GEO-environmental Society
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• v.9 no.6
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• pp.13-19
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• 2008

The objectives of this paper are to investigate states of these open dumping landfills for managing, utilizing and stabilization of a municipal solid waste landfill site in environmentally secure conditions. The result of the physical analysis of the landfill showed that it is composed of between 29.72-63.84% organic matter, 32.88% vinyl plastic. The environmental assessment of the landfill site confirmed that the landfill is at a maturation phase due to 0.18 of $BOD_5$/CODcr of leachate. VS and FS of TS Was respectively 30.37%, 32.34% and C/N ratio was 21.8. Surface water around landfill was BOD 10.7 mg/g, SS 37.8 mg/g, E-Coli 31,157(MPN/$100m{\ell}$) and Ground water was $COD_{Mn}$ 1.13-1.38 mg/g, $NO_3-N$ 1.025-4.075 mg/g. Leachat indicated T-P 0.002-0.028 mg/g, $NH_3-N$ 4.0-21.0 mg/g. The soil contamination of around landfill didn't appear as below of the regulation of Soil Environment Conservation Act. The Landfill Gas was $CH_4$ 13.25%, $CO_2$ 6.17%, H2S and CO was not detected. Also Surface Water was not detected $CO_2$, $CH_4$, $H_2S$, CO.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.42-45
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• 2008

It has been reported that FRP (fiber reinforced plastic) can be recycled by separating into layers instead of crushing into powder. F-fiber obtained from roving layer separated from FRP, has bigger tensile strength than the bundle of glass fibers of which FRP was made (more than 90%). SEM image of F-fiber shows the presence of some resin. Under the proposition of usage of F-fiber in the concrete material, tensile strength is examined after soaking in a basic solution (NaOH+KOH). The reaction mechanism of strength loss may be considered as an attack of hydroxide ion ($OH^-$) on a chemical bond of Si-O-Si of glass fiber. The simulation graph of the strength loss data implies certain reaction mechanism. While in the early stage kinetically controlled reaction results in a fast drop of tensile strength, after 30 days dispersion rate of hydroxide ion plays a major role in strength loss. This result is similar to the one for the AR glass. An extrapolation of the graph would make an assumption about the lift time of F-fiber possible.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.194-199
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• 2016

Presently, for the cement industry, studies that seek to reduce $CO_2$, because of the development of the plastic industry and demand for reduction of energy use, have been actively conducted among them, studies attempting to use Gamma-$C_2S({\gamma}-C_2S)$ to fix $CO_2$ have been actively conducted. The ${\gamma}-C_2S$ compound has an important function in reacting to $CO_2$ and stiffening through carbonatization in the air. The ${\gamma}-C_2S$ compound, reacting to $CO_2$ in the air, generates $CaCO_2$ within the pore structure of cement materials and densifies the pore structure this leads to an improvement of the durability and to the characteristic of resistance against neutralization. Therefore, in this experiment, in order to synthesize ${\gamma}-C_2S$, limestone sludge and waste foundry sands are used these materials are plasticized for 30 or 60 minutes at $1450^{\circ}C$, and are prevented from being cooled in the temperature range of $30{\sim}1000^{\circ}C$ when they are about to be cooled. XRD analysis and XRF analysis are used to determine the effects of this process on ${\gamma}-C_2S$ synthesization, the temperature at which a thing is plasticized, and the conditions for cooling that obtain in the plasticized clinker also, in order to confirm the $CO_2$ capture function, analysis of the major hydration products is conducted through an analysis of carbonatization depth and compressive strength, and through MIP analysis and XRD Rietveld analysis. As a result of these analyses, it is found that when ${\gamma}-C_2S$ was synthesized, the clinker that was plasticized at $1450^{\circ}C$ for one hour demonstrated the highest yield rate the sample with which the ${\gamma}-C_2S$ was mixed generated $CaCO_3$ when it reacted with $CO_2$ therefore, carbonatization depth and porosity were reduced, and the compressive strength was increased.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.329-334
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• 2005

The use of Polymer Concrete (PC) is growing very rapidly in many structural and construction applications such as box culverts, hazardous waste containers, trench lines, floor drains and the repair and overlay of damaged cement concrete surfaces in pavements, bridges, etc. However, PC has a defect economically because resin which be used for binder is expensive. Therefore the latest research is being progressed to replace existing resin with new resin which can reduce the high cost. Here, Polymer concrete using the recycled PET(polyethylene terephthalate) has some merits such as decrease of environmental destruction, decrease of environmental pollution and development of new construction materials. The variables of this study are amount of resin, curing condition and maximum size of coarse aggregate to find out mechanic properties of this. Stress-strain curve was obtained using MTS equipment by strain control. The results indicated that modulus of elasticity was increased gradually in an ascending branch of curve, as an increase of resin content. Compressive strength was the highest for resin content of $13\%$. And Compressive strength was increased as maximum size of coarse aggregate increases. The strain at maximum stress increases with an increase of resin content and size of coarse aggregate. For the descending branch of stress-strain curve the brittle fracture was decreased when it was cured at the room temperature compared to high temperature.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.21-30
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• 2015

Ceramic foams are prepared as positive images corresponding to a plastic foam structure which exhibits high porosities (85-90%). This structure makes the ceramic foams attractive as a catalyst in a dry reforming process, because it could reduce a high pressure drop problem. This problem causes low mass and heat transfers in the process. Furthermore, the reactants would shortly contact to catalyst surface, thus low conversion could occur. Therefore, this research addressed the preparation of dry reforming catalysts using a sol-gel catalyst preparation via a polymeric sponge method. The specific objectives of this work are to investigate the effects of polymer foam structure (such as porosity, pore sizes, and cell characteristics) on a catalyst performance and to observe the influences of catalyst preparation parameters to yield a replica of the original structure of polymeric foam. To accomplish these objectives industrial waste foams, polyurethane (PU) and polyvinyl alcohol (PVA) foams, were used as a polymeric template. Results indicated that the porosity of the polyurethane and polyvinyl alcohol foams were about 99% and 97%. Their average cell sizes were approximate 200 and 50 micrometres, respectively. The cell characteristics of polymer foams exhibited the character of a high permeability material that can be able to dip with ceramic slurry, which was synthesized with various viscosities, during a catalyst preparation step. Next, morphology of ceramic foams was explored using scanning electron microscopy (SEM), and catalyst properties, such as; temperature profile of catalyst reduction, metal dispersion, and surface area, were also characterized by $H_2-TPR$ and $H_2-TPD$ techniques, and BET, respectively. From the results, it was found that metal-particle dispersion was relatively high about 5.89%, whereas the surface area of ceramic foam catalysts was $64.52m^2/g$. Finally, the catalytic behaviour toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain operating conditions. The approaches from this research provide a direction for further improvement of marketable environmental friendly catalyst production.