• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.252-256
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• 2015

Nitrogen oxides ($NO_X$) was emitted from flue gas of stationary sources and exhaust gas of mobile sources, can leads to various environments problems. Selective Catalysts Reduction (SCR) is the most effective $NO_X$ removal system. Commercial $V_2O_5-WO_3/TiO_2$ catalysts, usually containing $V_2O_5$ 0.5~3 wt%, $WO_3$ 5~10 wt%, and $V_2O_5$ is active in the reduction of $NO_X$ but also in the desired oxidation of $SO_2$ to $SO_3$. To reduce the amount of vanadium, using graphene matrix supported vanadium to synthesize nanocomposite. Then, we fabricated to 1 inch honeycomb type of SCR catalysts adding graphene-vanadium nanocomposite. The chemical-physical characteristics and the catalytic activity were performed by XRD, XRF, BET and Micro-Reactor (MR). As a result, the De-NOX performance was showed, similar to the commercial catalyst activity as 77.8 % and using nanocomposite catalyst as 77.1 % at $350^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.9 no.4 s.29
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• pp.17-25
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• 2005

The dealuminated and alkali/alkaline-earth metal exchanged Y-zeolites were prepared as a catalyst. Elemental compositions and structures of the prepared catalysts were analyzed by the various spectroscopic techniques such as inductively coupled plasma-atomic emission spectroscopy(ICP-AES), X-ray fluorescence(XRF) and X-ray diffraction(XRD), and the desorption behaviors of adsorbed species on the catalyst surfaces were investigated via NO-TPD experiment. Comparing with the composition of the starting material of NaY zeolite, the magnitudes of Si/Al ratio in catalytic materials were increased after dealumination. The Si/Al ratio of catalytic materials after dealumination followed by Cs and Ba cation exchange were additionally decreased. Dealumination to catalysts induced a destruction of basic frame due to a detachment of aluminum, which results in reducing framework structure, while increasing non-framework structure. This phenomenon becomes more serious with increasing time of steam treatment and even more significant for the cation exchanged catalysts. In NO-TPD experiments, the desorption peaks of NO which indicates an activity point of catalysts shifted to the low temperature region after dealumination and cation exchange. The desorption peaks of the NO-TPD profiles taken after steam treatment also shifted to the low temperature region as the steam treatment time increased. In dealuminated and cation exchanged Y-zeolites, the catalytic activities were more influenced by exchanged cation and the formation of non-framework structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.537-543
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• 2019

Alumina(Al₂O₃) is a ceramic material used in industry with a range of particle sizes and characteristics. In this study, a boehmite sol was prepared by a hydrolysis and peptizing process using the Sol-Gel method from aluminum isopropoxide (AIP). γ-Al₂O₃ was prepared by drying and calcining. To prevent particle agglomeration during the manufacturing process, four kinds of polyvinyl alcohol (PVA) with molecular weights of 9,000~10,000, 31,000~50,000, 89,000~98,000, and 130,000 were added and three concentrations of HNO₃ (0.1, 0.3, 0.5 molar ratio) were added to determine their effects on the particles. The crystal structure, composition, particle size and shape of the prepared γ-Al₂O₃ were confirmed through x-ray diffraction (XRD), x-ray fluorescence analyzer (XRF), particle size analyzer (PSA), and field emission scanning electron microscopy (FE-SEM). As a result, γ-Al₂O₃ with a purity of approximately 98.2% was synthesized, and the particle size decreased and the uniformity increased with increasing ratio of HNO₃ addition and PVA molecular weight. From these results, the particle size can be controlled during the manufacturing process of γ-Al₂O₃ by controlling the addition ratio of PVA and HNO₃.

• Journal of Conservation Science
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• v.36 no.3
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• pp.162-177
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• 2020

Research was conducted to characterize the copper production and smelting process with 11 copper smelting by-products (copper slag and copper crucible) excavated from the NA and LA areas at the Gwanbuk-ri archeological site in Buyeo. Scanning electron microscopy-energy dispersive spectroscopy, wavelength dispersive X-ray fluorescence, X-ray diffraction, and Raman microspectroscopy were employed in the analysis. The research results reveal that the copper slag from Gwanbuk-ri contained silicate oxide, magnetite, fayalite, and delafossite, which are typical characteristics of crucible slag and refined slag. The outward appearance and microstructure of the slag were grouped as follows: 1. glassy matrix + Cu prill, 2. glassy matrix + Cu prill + magnetite, 3. silicate mineral matrix + Cu prill, 4. crystalline (delafossite and magnetite) + amorphous (Cu prill), 5. magnetite + fayalite, and 6. slag from slag. The copper slags from Guanbuk-ri were found to contain residues of impurities such as SiO₂, Al₂O₃, CaO, SO₄, P₂O₅, Ag₂O, and Sb₂O₃ in their microstructure, and, in some cases, it was confirmed that copper, tin and lead are alloys. These results indicate that refining of intermediate copper(including impurities) and refining of alloys of copper(including impurities) - tin and refining of copper(including impurities) - tin - lead took place during the copper production process at Gwanbuk-ri, Buyeo.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.459-467
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• 2016

In order to assess the pollution status and distribution characteristics of PM and PM-bound species, PM10 samples were collected using mini-volume air sampler at the subway cabin in Daejeon city. Measurements of about 24 elements including toxic metals (e.g., As, Cr, Mn, V, Zn) in PM10 were made by instrumental neutron activation analysis and X-ray fluorescence. The average PM10 concentration was $59.3{\pm}14.5{\mu}g/m^3$ in the subway cabin with a range of 42.2 to $97.4{\mu}g/m^3$, while the associated elemental concentrations were varied in the range of $10^{-3}$ to $10^5ng/m^3$. It was found that the concentration of Fe ($12.5{\mu}g/m^3$) was substantially higher than any other element. The Fe concentration was apportioned by about 20% of the PM10 concentration. The results of factor analysis indicate that there are no more than six sources in the cabin (e.g., brake-nonferrous metal particle, resuspended rail dust, fuel combustion, vehicle exhaust, black carbon, Cr-related).

• Journal of Periodontal and Implant Science
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• v.49 no.6
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• pp.366-381
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• 2019

Purpose: The purpose of this study was to evaluate the effectiveness of conventional sandblasted, large-grit, acid-etched (SLA) surface coated with a pH buffering solution based on surface wettability, blood protein adhesion, osteoblast affinity, and platelet adhesion and activation. Methods: Titanium discs and implants with conventional SLA surface (SA), SLA surface in an aqueous calcium chloride solution (CA), and SLA surface with a pH buffering agent (SOI) were prepared. The wetting velocity was measured by the number of threads wetted by blood over an interval of time. Serum albumin adsorption was tested using the bicinchoninic acid assay and by measuring fluorescence intensity. Osteoblast activity assays (osteoblast adhesion, proliferation, differentiation, mineralization, and migration) were also performed, and platelet adhesion and activation assays were conducted. Results: In both the wetting velocity test and the serum albumin adsorption assay, the SOI surface displayed a significantly higher wetting velocity than the SA surface (P=0.000 and P=0.000, respectively). In the osteoblast adhesion, proliferation, differentiation, and mineralization tests, the mean values for SOI were all higher than those for SA and CA. On the osteoblast migration, platelet adhesion, and activation tests, SOI also showed significantly higher values than SA (P=0.040, P=0.000, and P=0.000, respectively). Conclusions: SOI exhibited higher hydrophilicity and affinity for proteins, cells, and platelets than SA. Within the limits of this study, it may be concluded that coating an implant with a pH buffering agent can induce the attachment of platelets, proteins, and cells to the implant surface. Further studies should be conducted to directly compare SOI with other conventional surfaces with regard to its safety and effectiveness in clinical settings.

• BMB Reports
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• v.40 no.3
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• pp.315-324
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• 2007

The novel $\alpha$-amylase purified from locally isolated strain, Bacillus sp. KR-8104, (KRA) (Enzyme Microb Technol; 2005; 36: 666-671) is active in a wide range of pH. The enzyme maximum activity is at pH 4.0 and it retains 90% of activity at pH 3.5. The irreversible thermoinactivation patterns of KRA and the enzyme activity are not changed in the presence and absence of $Ca^{2+}$ and EDTA. Therefore, KRA acts as a $Ca^{2+}$-independent enzyme. Based on circular dichroism (CD) data from thermal unfolding of the enzyme recorded at 222 nm, addition of $Ca^{2+}$ and EDTA similar to its irreversible thermoinactivation, does not influence the thermal denaturation of the enzyme and its Tm. The amino acid sequence of KRA was obtained from the nucleotide sequencing of PCR products of encoding gene. The deduced amino acid sequence of the enzyme revealed a very high sequence homology to Bacillus amyloliquefaciens (BAA) (85% identity, 90% similarity) and Bacillus licheniformis $\alpha$-amylases (BLA) (81% identity, 88% similarity). To elucidate and understand these characteristics of the $\alpha$-amylase, a model of 3D structure of KRA was constructed using the crystal structure of the mutant of BLA as the platform and refined with a molecular dynamics (MD) simulation program. Interestingly enough, there is only one amino acid substitution for KRA in comparison with BLA and BAA in the region involved in the calcium-binding sites. On the other hand, there are many amino acid differences between BLA and KRA at the interface of A and B domains and around the metal triad and active site area. These alterations could have a role in stabilizing the native structure of the loop in the active site cleft and maintenance and stabilization of the putative metal triad-binding site. The amino acid differences at the active site cleft and around the catalytic residues might affect their pKa values and consequently shift its pH profile. In addition, the intrinsic fluorescence intensity of the enzyme at 350 nm does not show considerable change at pH 3.5-7.0.

• Clinical and Experimental Reproductive Medicine
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• v.29 no.2
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• pp.139-147
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• 2002

Objective : This study was to establish a reproducible differentiation system from the parthenogenetic mouse embryonic stem (P-mES02) cells into functional cardiomyocytes like as in vitro fertilization mouse embryonic stem (mES01) cells. Materials and Methods: To induce differentiation, P-mES02 cells were dissociated and aggregated in suspension culture environment for embryoid body (EB) formation. For differentiation into cardiomyocytes, day 4 EBs were treated with 0.75% dimethyl sulfoxide (DMSO) for another 4 days (4-/4+) and then were plated onto gelatin-coated dish. Cultured cells were observed daily using an inverted light microscope to determine the day of contraction onset and total duration of continuous contractile activity for each contracting focus. This frequency was compared with the results of DMSO not treated P-mES02 group (4-/4-) and mES01 groups (4-/4+ or 4-/4-). For confirm the generation of cardiomyocytes, beating cell masses were treated with trypsin-EDTA, dispersed cells were plated onto glass coverslips and incubated for 48 h. Attached cells were fixed using 4% paraformaldehyde and incubated with specific antibodies (Abs) to detect cardiomyocytes (anti-sarcomeric ? -actinin Ab, 1 : 100; anti-cardiac troponin I Ab, 1 : 2000) for 1 h. And the cells were finally treated with FITC or TRITC labelled 2nd Abs, respectively, then they were examined under fluorescence microscopy. Results: Rhythmically contracting areas in mES01 or P-mES02 cells were firstly appeared at 9 or 10 days after EBs plating, respectively. The highest cumulative frequency of beating EBs was not different in both treatment groups (mES01 and P-mES02, 4-/4+) with the results of 61.3 % at 13 days and 69.8% at 15 days, respectively. Also, the contracting duration of individual beating EBs was different from minimal 7 days to maximal 53 days. However, DMSO not treated groups (mES01 and P-mES02, 4-/4-) also had contracting characteristics although their frequency was a few compared to those of DMSO treated groups (6.0% and 4.0%). Cells recovered from the spontaneously contracting areas within EBs in both treated groups were stained positively with muscle specific anti-sarcomeric ? -actinin Ab and cardiac specific anti-cardiac troponin I Ab. Conclusion: This study demonstrated that the P-mES02 cell-derived cardiomyocytes displayed similarly structural properties to mES01 cell-derived cardiomyocytes and that the DMSO treatment enhanced the cardiomyocytes differentiation in vitro.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.196-203
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• 2004

To understand the geochemical processes in the Han River Estuary, distributions and behaviors of nutrients, dissolved organic matters, and uranium were investigated and analyzed during estuarine tidal mixing in June 2000 and February 2001. The distribution of inorganic nutrients showed very dynamic distributional patterns implying an apparent nitrification process and a concave non-conservative mixing along the salinity gradient. Dissolved organic carbon was high in the upstream region and decreased sharply in the low salinity region of around 5 psu. The 3-D fluorescence characteristic of dissolved organic matter showed two distinct fluorophores in the study area. Biomacromolecules originated mainly from the indigenous biochemical processes and geomacromolecules from terrestrial humic materials. In the study area, the distribution of geomacromolecule showed a concave non-conservative property along the salinity gradient presumably due to the flocculation and removal processes in the estuary. Meanwhile, distribution of the dissolved uranium, mainly in the form of stable uranium carbonate complex, also showed a concave non-conservative property along the salinity gradient in the Han River Estuary. From this study, the removal rate of dissolved uranium in the Han River Estuary was estimated to be about 7.1 ton per year.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.5
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• pp.359-366
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• 2013

This work is investigated for the catalytic decomposition of hydrogen iodide (HI). Platinum was used as active material by loading on $ZrO_2-SiO_2$ mixed oxide in HI decomposition reaction. To obtain high and stable conversion of hydrogen iodide in severe condition, it was required to improve catalytic activity. For this reason, a method increasing dispersion of platinum was proposed in this study. In order to get high dispersion of platinum, zirconia was incorporated in silica by sol-gel synthesis. Incorporating zirconia influence increasing platinum dispersion and BET surface area as well as decreasing deactivation of catalysts. It should be able to stably product hydrogen for a long time because of inhibitive deactivation. HI decomposition reaction was carried out under the condition of $450^{\circ}C$ and 1 atm in a fixed bed reactor. Catalysts analysis methods such as $N_2$ adsorption/desorption analysis, X-ray diffraction, X-ray fluorescence, ICP-AES and CO gas chemisorption were used to measurement of their physico-chemical properties.