• Resources Recycling
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• v.32 no.6
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• pp.45-53
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• 2023

This study discussed the trend and future strategy of adsorption technology R&D to effectively recover ammonia emitted from the livestock fields. A proper ammonia adsorbent should incorporate acidic or hydrogen bonding functional groups on the surface, as well as a high specific surface area and a good surface structure appropriate for ammonia adsorption. Activated carbon and minerals such as zeolite have widely been used as ammonia adsorbents, but their adsorption effects are generally low, so any improvement through surface modification should be necessary. For example, incorporation of metal chloride included in a porous adsorbent can promote ammonia adsorption effectiveness. Recently, new types of adsorbents such as MOFs (Metal-Organic Frameworks) and POPs (Porous Organic Polymers) have been developed and utilized. They have shown very high ammonia adsorption capacity because of adjustable and high specific surface area and porosity. In addition, Prussian Blue exhibited high ammonia adsorption and desorption performance and selectivity. This looks relatively advantageous in relation to the recovery of ammonia from livestock waste discharge. In the future, further research should be made to evaluate ammonia adsorption/desorption efficiency and purity using various adsorbents under conditions suitable for livestock sites. Also, effective pre- and/or post-treatment processes should be integrated to maximize ammonia recovery.

• Resources Recycling
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• v.30 no.3
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• pp.41-46
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• 2021

Methanesulfonic acid (MSA) can be considered effective in the leaching of metals because of its advantageous physical and chemical properties. The chemical reactivities of MSA and sulfuric acid were compared based on their structures and the dissolution data of Co and Ni metal. The inductive and resonance effects play a vital role in the chemical reactivities of these two acids. The dissolution percentages of Co and Ni in the sulfuric acid solution were higher than those in the MSA solution under the same experimental conditions. Considering the strong acidity of MSA and the high solubility of its metal salts, MSA can be employed as a leaching agent for the recovery of metals.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.29-34
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• 2004

Biosorption technology is recognized as an economically feasible alternative for the removal and/or recovery of metal ions from industrial wastewater sources. However, the structure of biosorbents is quite complex when compared with synthetic ion-exchange resins, which makes it difficult to quantify the ion-binding sites. Accordingly, this report describes a well-defined method to characterize the pK values and numbers of biomass functional groups from potentiometric titration data. When the proposed method was applied to Sargassum polycystum biomass as a model biosorbent, it was found that the biomass contained three types of functional groups. In addition, the carboxyl group (pK=$3.7{\pm}0.09$) was found to be the major binding sites ($2.57{\pm}0.06 mmol/g$) for positively-charged heavy-metal ions.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.51-55
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• 2022

Generally, Au electrodes are the preferred top metal electrodes in most perovskite solar cells (PSCs) because of their appropriate work function for hole transportation and their resistance to metal-halide formation. However, for the commercialization of PSCs, the development of alternative metal electrodes for Au is essential to decrease their fabrication cost. Ag electrodes are considered one of the most suitable alternatives for Au electrodes because they are relatively cheaper and can provide the necessary stability for oxidation. However, Ag electrodes require an aging-induced recovery process and react with halides from perovskite layers. Herein, we propose a bilayer Au/Ag electrode to overcome the limitations of single Au and Ag metal electrodes. The performance of PSCs based on bilayer electrodes is comparable to that of PSCs with Au electrodes. Furthermore, by using the bilayer electrode, we can eliminate the aging process, normally an essential process for Ag electrodes. This study not only demonstrates an effective method to substitute for expensive Au electrodes but also provides a possibility to overcome the limitations of Ag electrodes.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.663-672
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• 2007

The mutual separation behavior of actinides and rare earths in a countercurrent multistage reductive extraction system was predicted by computer calculation. The distribution information for actinides and rare earths in the reductive extraction systems of LiCl-KCl/Cd and LiCl-KCl/Bi was collected from literature and then it was used for the calculation of a multistage extraction. The results of the concentration profiles throughout the extraction cascade, recovery yields of various metal solutes, and separation factors between the actinides and rare earths were calculated. The effects of the major process parameters, such as reducing agent content in the metal phase, number of stages, and salt/metal flow ratio, etc., on the extraction behavior were also examined.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.126-141
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• 1997

The purpose of this research is to develope a FEM program for analyzing solidification processes of axisymmetric casting, considering phase changes and the contact between the metal and mold. Tempera- ture recovery method is employed fro considering the phase changes releasing the latent heat and the coin- cident node method is used for calculating the amount of heat transfer between the metal and mold. Tan- gent modulus algorithm is adopted for calculating flow stress and a gap element is employed for modeling the interface between the mold and metal in finding deformed shapes. In order to verify the developed program, axisymmetric aluminum and steel casting processes are simulated. Temperature distribution, phase front position, and shrinkage and porosity creation are compared with measurements, FIDAP results, and good agreements are examined.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.188-191
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• 1997

In the recent sheet metal forming simulations, it increases to adopt the dynamic explicit method for an effective computation and the elastic-plastic formulation for stress recovery. It is inevitable in the dynamic explicit method that some noises occur and sometimes partly spoil results of simulations. It is severer when complicated contact conditions are included in simulations. An effective method to control these noises is introduction of damping effects. In this paper, the concept of contact damping is introduced in order to suppress noises due to complicated contact conditions. This is checked by analyzing a simple sheet metal forming process(U-bending). From the computational results, it is shown that the contact damping can effectively control the noises due to contacts and develop more reliable internal stress states.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.242-246
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• 2005

The heavy metal analysis (Cd, Pb, Cu, Cr, Zn, Ni) with various extraction methods was performed using the certified sample and real soil sample. In case of the certified samples, $10.5{\sim}118%$ of recovery was showed with various ranges depend on the metal kinds and extraction methods. Also, the alkali-digestion method was showed the proper results by applying in hexavalent chromium. In case of real sample, compared to amounts of heavy metals extracted using 0.1N-HCl, those extracted using acid digestion are higher by $3{\sim}24$ times in Cu, $1.1{\sim}1.5$ times in Cd, $2{\sim}23$ times in Pb, $3{\sim}104$ times in Zn, $12{\sim}101$ times in Ni, $30{\sim}202$ times in Cr. There is no considerable difference between four acid digestion methods.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.306-312
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• 1999

In the recent sheet metal forming simulations, it increases to adopt the dynamic explicit method for an effective computation and the elastoplastic formulation for stress recovery. It is inevitable in the dynamic explicit method that some noises occur, which sometimes partly spoil results of simulations. This phenomenon becomes severer when complicate contact conditions are included in simulations. In commercial dynamic codes, the concept of contact damping is introduced. However, the formulation process of it is not revealed well. In this paper, a contact damping method is formulated in order for effectively suppressing noises occurring due to complicated contact conditions. This is checked by analyzing a simple sheet metal stamping process (U-draw bending). From the computational results, it is shown that the contact damping can effectively control the noises due to contacts, especially when considering the sheet thickness, and help to develop more reliable internal stress states, which result in more realistic shapes after springbank.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.122-128
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• 1994

Macrocyclic ligand has been known to selectively bind with metal ions so that ability applied for the transport of metal ions across the emulsion liquid membrane in this study. The metal ions are transproted from the source phase to the receiving phase by the carrier of the organic phase. Several factors involved in the transport of metal ions acrose the emulsion membrane we reported here and these factors provided the informations for the selective seperation of some metal ion. Stability constants for cation-macrocyclic ligand and metal ion-anion receiving phase interaction are examined as parameters for the prediction of metal ion transport selectivities. $Pb^{2+}$ was transported higher rates than the other metal ions in the mixture solution. The interaction of metal ion to anion in receiving phase is important. $S_2O_3^{2-}$- in replacement of $NO_3^-$ in the receiving phase enhances the transport of $Pb^{2-}$since $Pb^{2-}-S_2O_3^{2-}$interaction is greater than $Pb^{2+}-NO_3^-$ interaction.