• Resources Recycling
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• v.17 no.1
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• pp.59-65
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• 2008

The adsorption features of nickel ion in wastewater on manganese dioxide from spent batteries were investigated for its usage as an adsorbent. The aquatic behavior of nickel ion was characterized by MINTEQ program and the considered influential variables on the adsorption of nickel ion were its initial concentration, reaction temperature, the amount of adsorbent, and pH. The adsorption ratio of nickel ion decreased with increasing its initial concentration and thermodynamic estimation has been carried out based on the adsorption characteristics of nickel ion depending on temperature. In addition, the adsorption of nickel ion was shown to be promoted according to the amount of manganese dioxide and a lot of nickel ions were adsorbed as the solution pH was raised.

• Journal of Science and Technology Studies
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• v.2 no.1 s.3
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• pp.135-156
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• 2002

The view of technology is largely divided into 2 theories: (1) the theory of autonomous technology that claims technology's own development logic and momentum, (2) the theory of social determinism that regards technology as reflection of political choices. Autonomous technologists read our society in the language of technology and social determinists read our technology in the language of society. This paper tries to analyze that conflicts between government and environmental group in nuclear policy, especially radioactive waste disposition policy reflect collisions between autonomous technologists and social determinists representing technology and politics, respectively. On the surface, such collisions are occurred in rational, ethical and economical aspects. It maintains, however, in depth, they are about solution means to problems from which technologies derived. Also, it suggests that one of the alternatives to avoid inevitable collision may be interaction approach based on intertwining technology with society. More understanding of political natures and control possibilities for technology is needed because interaction approach is founded on this understanding. Finally, to help forming the Korea's nuclear utilization policy from now on, it gives 2 case studies compared France with Germany where expanding and contracting nuclear utilization policy, respectively.

• Advances in environmental research
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• v.3 no.3
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• pp.231-251
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• 2014

The present study examines the phosphate adsorption potential and behavior of mixture of Ground Burnt Patties (GBP), a solid waste generated from cooking fuel used in earthen stoves and Red Soil (RS), a natural substance in fixed bed column mode operation. The characterization of adsorbent was done by Proton Induced X-ray Emission (PIXE), and Proton Induced ${\gamma}$-ray Emission (PIGE) methods. The FTIR spectroscopy of spent adsorbent reveals the presence of absorbance peak at $1127cm^{-1}$ which appears due to P = O stretching, thus confirming phosphate adsorption. The effects of bed height (10, 15 and 20 cm), flow rate (2.5, 5 and 7.5 mL/min) and initial phosphate concentration (5 and 15 mg/L) on breakthrough curves were explored. Both the breakthrough and exhaustion time increased with increase in bed depth, decrease in flow rate and influent concentration. Thomas model, Yoon-Nelson model and Modified Dose Response model were used to fit the column adsorption data using nonlinear regression analysis while Bed Depth Service Time model followed linear regression analysis under different experimental condition to evaluate model parameters that are useful in scale up of the process. The values of correlation coefficient ($R^2$) and the Sum of Square Error (SSE) revealed the Modified Dose Response model as the best fitted model to the experimental data. The adsorbent mixture responded effectively to the desorption and reusability experiment. The results of this finding advocated that mixture of GBP and RS can be used as a low cost, highly efficient adsorbent for phosphate removal from aqueous solution.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.61-66
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• 1998

An artificial zeolite was synthesized from bituminous coal fly ash by thermo-alkali treatment, $100{\pm}3^{\circ}C$ and 3.5 N NaOH solution for 24 hours, to develope new useful material in waste water treatment system. The artificial zeolite had much higher cation exchange capacity, $299cmol^+\;kg^{-1}$ and lower concentration of extractable heavy metals than bituminous coal fly ash. The higher the temperature and the longer the shaking time, the more Zn, Cu, Cd and Pb were sorbed chemically by the artificial zeolite. Shaking artificial zeolite and wastewater at $35^{\circ}C$ for 9 hours, the amount of sorbed heavy metals were $123.5g\;kg^{-1}$ for Zn, $164.7g\;kg^{-1}$ for Cu, $184.4g\;kg^{-1}$ for Cd and $350.6g\;kg^{-1}$ for Pb, respectively.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.54-61
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• 2019

In this study, a magnetic adsorbent was synthesized by growing ferrite nanoparticles substituted with metals (Me = Co, Mn, Ni) on zeolite 4A for the efficient separation of waste adsorbents present in the solution after the adsorption of Cu(II). The metal ferrite grown on the surface of zeolite was prepared by solvothermal synthesis. Characteristics of the magnetic adsorbent were analyzed by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and physical property measurement system (PPMS). The saturation magnetization of the A type zeolite coated with Co-ferrite (CFZC) was the highest at 5 emu/g and the Cu(II) adsorption performance was also excellent. The adsorption results of Cu(II) on CFZC were well fitted by the Langmuir model at 298 K. Also, the adsorption of Cu(II) on CFZC follows a pseudo-second order kinetic. The Gibbs free energy values (${\Delta}G^0$) ranging from -4.63 to -5.21 kJ/mol indicates that the Cu(II) adsorption is spontaneous in the temeprature range between 298 and 313 K.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1524-1530
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• 2018

In this paper, we designed a product that can prevent environmental pollution, waste of resources, and leakage of foreign currency by commercializing a green IT solution by merging a used smart phone with the IoT object communication technology for the first time in the world. For the experiment of the designed system, various performance and communication condition was experimented by installing it in the actual crop cultivation facility. As a result, when a problem occurs, the alarm sound and video notification are generated by the user's smart phone, and remote control of various installed devices and data analysis in real time are possible. In this study, it is thought that the terminal management board developed for the utilization of the used smart phone can be applied to various fields such as agriculture and environment.

• Biomaterials and Biomechanics in Bioengineering
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• v.4 no.1
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• pp.21-32
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• 2019

Eggshell is a waste material after the usage of egg. In this work, biowaste chicken eggshells were used for preparing carbonated hydroxyapatite (HA) nanoparticles of high purity through aqueous precipitation method at room temperature. The eggshell-derived HA will be a cost-effective bioceramics for biomedical applications and an effective material-recycling technology. Additionally, mulberry leaf extract was used as a template to regulate the morphology, size and crystallinity of HA, and the effects of pH value were also examined. Characterization of the samples was performed by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) was used to determine the size, shape and morphology of HA. The results indicate that only one phase of HA were synthesized in the both absence and presence of mulberry leaf extract at pH of 7 and above, while DCPD or DCPA/DCPD phase was observed at pH 4 condition. The crystallite sizes of the HA samples obviously decreased when adding mulberry leaf extract as a template, while they decreased gradually as the solution pH levels increased. With increasing pH level from 7 to 14, the rod-like HA nanoparticles gradually changed to spherical shape at pH 14. Note that, the obtained product is Mg and Sr containing A- and B-type carbonate HA at alkaline pH and it can be a potential material for biomedical applications.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.281-288
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• 2020

BACKGROUND: Generally, ammonia occurs from agricultural waste disposal. Ammonia is known as a harmful substance to the human body and has a bad influence such as eutrophication on the ecosystem. It is possible to remove the ammonia by ammonia adsorption method using natural zeolite, without external influence. However, due to the natural zeolite shape, it is hard to reuse. METHODS AND RESULTS: Electrospinning method can produce fiber with constant diameter. Moreover, electrospinning method has no limitation for selecting the material to make the fiber, and thus, it is valuable to reform the surface of adsorbent. In this study, reusable membrane was made by electrospinning method. The highest removal efficiency was shown from the membrane with 20% of zeolite included, and it has been verified that it is possible to reuse the membrane through chemical treatment. The highest ammonia removal efficiency was about 92.4%. CONCLUSION: In this study, ammonia adsorption characteristics of zeolite fibers were studied. Electrospinning method can produce zeolite fiber with even distribution. Ammonia can be removed efficiently from ion exchange ability of the natural zeolite. The result of adsorption isotherm indicated that both Freundlich model and Langmuir model provided the best fit for equilibrium data. And study on desorption has demonstrated that the ion exchange from zeolite was reversible when 0.01 M NaCl and KCl solution were used.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.13-28
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• 2021

Since transient electronic devices can operate under harsh conditions such as electrolytic solutions or inside the body, and be removed by hydrolysis after operation, they can replace conventional electronic devices in various research areas like biomedical implantable devices. Moreover, transient electronic devices that can dissolve in water and enzymes are the focus of the new concept of green technology, which can solve electrical waste issues. However, the surroundings of transient electronic devices can deteriorate internal device components. Thus, an encapsulation strategy is introduced for stable operation in solution by shielding the outside of a device with a passive barrier. This article summarizes recent research trends in transient electronic devices, including their background, dissolution behavior, and encapsulation strategies to enhance reliability by blocking water permeation.

• Advances in environmental research
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• v.10 no.1
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• pp.87-103
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• 2021

Anaerobic digestion (AD) refers to the biological process which can convert organic substrates to biogas in the absence of oxygen. The aim of this study was to determine the capability of feedstock to produce biogas and to quantify the biogas yield from different feedstocks. A co-digestion approach was carried out in a continuous stirred tank reactor operated under mesophilic conditions and at a constant organic loading rate of 0.0756 g COD/ L.day, with a hydraulic retention time of 25 days. For comparison, mono-digestion was also included in the experimental work. 2 L working volumes were used throughout the experimental work. The seed culture was obtained from composting as substrate digestion. When the feedstock was added to seeding, the biogas started to emit after three days of retention time. The highest volume of biogas was observed when the seeding volume used for 1000mL. However, the lowest volume of biogas yield was obtained from both co-digestion reactors, with a value of 340 mL. For methane yield, the highest methane production rate was 0.16 L CH4/mg. The COD with yield was at 8.6% and the lowest was at 0.5%. The highest quantity of methane was obtained from a reactor of Euphorbiaceae peel with added seeding, while the lowest methane yield came from a reactor of Euphorbiaceae stems with added seeding. In this study, sodium bicarbonate (NaHCO3) was used as a buffering solution to correct the pH in the reactor if the reactor condition was found to be in a souring or acidic condition.