• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.351-359
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• 2013

Blast furnace slag (BFS) have many advantages that are related to effective value improvement on applying to concrete while side effects of blast furnace slag also appear. Thus, research team conducted an experiment with high volume slag to see if the attribute of waste alkali accelerator for mixing rate, mixed use of NaOH and $Na_2SiO_3$, and early strength agent for mixing rate for replacement ratio and for the types of the stimulants in order to increase the use of blast furnace slag1s powder. As the result of the experiment, when it comes to compression strength, all of the alkali stimulants have been improved as the replacement rate increases except for sodium hydroxide. Among the alkali stimulants, sodium silicate was high on dynamic elastic modulus and absorption factor. In case of early strength agent, the mix of mixing 1.5% and blast furnace slag 75% have showed high strength enhancement. In event of Waste Alkali accelerator, it has showed different consequences for each experiment.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.485-492
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• 2012

Dense and single phase $BiFeO_3$ (BFO) ceramics were prepared using attrition milled calcined (coarse) powders of an average particle size of ${\approx}3{\mu}m$ by conventional sintering process. A relative density of ${\approx}96%$ with average grain size $7.3{\mu}m$ was obtained when the powder compacts were sintered at $850^{\circ}C$ even for a shorter duration of 10 min. In contrast, densification barely occurred at $800^{\circ}C$ for up to 12 h rather the microstruce showed the growth of abnormal grains. The grain growth behavior at different temperatures is discussed in terms of nonlinear growth rates with respect to the driving force. The sample sintered at $850^{\circ}C$ for 12 h showed enhanced electrical properties with leakage current density of $4{\times}10^{-7}A/cm^2$ at 1 kV/cm, remnant polarization $2P_r$ of $8{\mu}C/cm^2$ at 20 kV/cm, and minimal dissipation factor (tan ${\delta}$) of ~0.025 at $10^6$ Hz. These values are comparable to the previously reported values obtained using unconventional sintering techniques such as spark plasma sintering and rapid liquid phase sintering.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.161-166
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• 2020

In accordance with the amendment of the Industrial Safety and Health Act of 2007, Korea completely prohibited the import, distribution and manufacture of asbestos like Europe and Japan. Accordingly, the current problem of asbestos is the safe maintenance and disposal of asbestos construction material, the disposal of asbestos, and the final disposal of asbestos building materials. If the asbestos building material is made harmless, it may be classified as general waste or as recyclable waste. Therefore, this study evaluated the physical and chemical characterization of detoxified asbestos powder and the applicability of secondary products. In this study, it was found that applying the appropriate temperature and pressure for catalysis during asbestos desalination through low temperature chemical treatment was the most important factor.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1166-1172
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• 2018

Degradation due to delamination occurs frequently in the high temperature superconductors (HTS) coil of rotating machines made with 2nd generation (2G) HTS wire, and the authors have observed other similar cases. Since an HTS field coil for a rotating machine is required to have stable current control and maintain a steady state, co-winding techniques for insulation material and epoxy resin for shape retention and heat transfer improvement are applied during coil fabrication. However, the most important limiting factor of this technique is delamination, which is known to be caused by the difference in thermal expansion between the epoxy resin and 2G HTS wire. Therefore, in this study, the experimental results of mixing the ratio of epoxy resin and alumina ($Al_2O3$) filler were applied to the fabrication of small and large test coils to solve the problem of degradation. For the verification of this scheme, eight prototypes of single pancake coils with different shapes were fabricated. They showed good results. The energization and operation maintenance tests of the stacked coils were carried out under liquid neon conditions similar to the operation temperature of an MW-class rotating machine. In conclusion, it was confirmed that the alumina powder mixed with epoxy resin in an appropriate ratio is an effective solution of de-lamination problem of 2G HTS coil.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.67-74
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• 2002

A phosphor for Plasma Display Panel, BaMgAl$_{10}$ O$_{17}$ :Eu$^{2+}$, showing a blue emission band at about 450nm was prepared by a solid-state reaction using BaCO$_3$, $Al_2$O$_3$, MgO, Eu$_2$O$_3$ as starting materials wish flux AlF$_3$. The study of the behaviour of Eu in BAM phosphor was carried out by the photoluminescence spectra and the Rietveld method with X-ray and neutron powder diffraction data to refine the structural parameters such as lattice constants, the valence state of Eu, the preferential site of Mg atom and the site fraction of each atom. The phenomenon of the concentration quenching was abound 2.25~2.3wt% of Eu due to a decrease in the critical distance for energy transfer of inter-atomic Eu. Through the combined Rietveld refinement, R-factor, R$_{wp}$, was 8.11%, and the occupancy of Eu and Mg was 0.0882 and 0.526 at critical concentration. The critical distance of Eu$^{2+}$ in BAM was 18.8$\AA$ at 2.25% Eu of the concentration quenching. Furthermore, c/a ratio was decreased to 3.0wt% and no more change was observed over that concentration. The maximum entropy electron density was found that the modeling of $\beta$-alumina structure in BaMgAl$_{10}$ O$_{17}$ :Eu$^{2+}$correct coincided showing Ba, Eu, O atoms of z= 1/4 mirror plane.e.ane.e.

• The Journal of Korean Obstetrics and Gynecology
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• v.18 no.1
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• pp.142-155
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• 2005

Objective: This study was undertaken to evaluate the dose dependent effects of Epimedii Herba extract solution on the spermatogenic abilities such as concentration, motility and morphological normality of sperm from the testis, and the activities of spermhyaluronidase and antioxidants. Materials and Method: We choose the 2-month-old mice, and administered the extract powder of Epimedii Herba in the different concentration once in a day for 60 days. The control group was administerde to normal water in the isolated testis tissue. Also we observed changes of isolated testis at the before and after administration of Epimedii Herba extracts in the mice. And we compared to the testicular tissue especially seminiferous tubules between control and treated group by histochemical methods. Results: The significant dose dependent differences were observed in the concentration of total sperm, the motility and normality of spermatozoa of the Epimedii Herba extract administered groups compared than that of control group, respectively. In the histological analysis of the testicular lobes were observed in the Epimedii Herbaextract administered groups than control group, respectively. Also, the activity hyluronidase was significantly increased in the Epimedii Herba extract administered groups than that of the control group. In case of antioxidant activity analysis, the activity of peroxidase and catalase were significantly increased in the Epimedii Herba extract administered groups than that of control group, respectively. Conclusion: This study shows that Epimedii Herba can effect the count and motility of sperm, the important ractor in male fertility and also promote the activity of antioxidants, catalase and peroxidase, which is the important factor in spermatogenesis.

• The Journal of Pediatrics of Korean Medicine
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• v.22 no.1
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• pp.103-111
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• 2008

Objectives Seunggal-tang is one of the prescriptions of oriental herbal medicine, which has been applied to several allergic diseases such as atopic dermatitis. This study was planned to compare differences of anti-allergic effects based on different form of Seunggal-tang by manufacturing differently. Methods Two types herb medicine products were used; aqueous extract (SG-T, Seunggal-Tang) and powder (SG-S, Seunggal-San) which were made from the same mixed formula of Seunggal-tang. To investigate in vitro anti-allergic activities, rat basophilic leukemia (RBL-2H3) cells were treated with SG-T and SG-S for 1 hour, and then stimulated with the phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187. We examined the release of beta-hexosaminidase, as a marker of degranulation, and the releases of tumor necrosis factor (TNF)-alpha and interleukin (IL)-4, as proinflammatory cytokines. Results SG-T and SG-S didn't have effects on cell viabilities in concentrations under 2㎎/㎖. In additionto that, SG-T more inhibited releasing ${\beta}$-hexosaminidase, TNF-${\alpha}$ and IL-4 than SG-S. Conclusions These results indicate that SG-T is more effective against mast cell-mediated allergic reactions than SG-S.

• Journal of Periodontal and Implant Science
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• v.49 no.3
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• pp.193-204
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• 2019

Purpose: The reaction of cells to a titanium implant depends on the surface characteristics of the implant which are affected by decontamination. The aim of this study was to evaluate the cytocompatibility of titanium disks treated with various decontamination methods, using salivary bacterial contamination with dental pellicle formation as an in vitro model. Methods: Sand-blasted and acid-etched (SA) titanium disks were used. Three control groups (pristine SA disks [SA group]; salivary pellicle-coated SA disks [pellicle group]; and biofilm-coated, untreated SA disks [NT group]) were not subjected to any decontamination treatments. Decontamination of the biofilm-coated disks was performed by 14 methods, including ultrasonic instruments, rotating instruments, an air-powder abrasive system, a laser, and chemical agents. MG63 cells were cultured in the presence of the treated disks. Cell proliferation assays were performed on days 2 and 5 of cell culture, and cell morphology was analyzed by immunofluorescence and scanning electron microscopy (SEM). A vascular endothelial growth factor (VEGF) assay was performed on day 5 of culture. Results: The cell proliferation assay revealed that all decontaminated disks, except for the 2 groups treated using a plastic tip, showed significantly less cell proliferation than the SA group. The immunofluorescence and SEM analyses revealed that most groups showed comparable cell density, with the exception of the NT group, in which the cell density was lower and bacterial residue was observed. Furthermore, the cells grown with tetracycline-treated titanium disks showed significantly lower VEGF production than those in the SA group. Conclusions: None of the decontamination methods resulted in cytocompatibility similar to that of pristine SA titanium. However, many methods caused improvement in the biocompatibility of the titanium disks in comparison with the biofilm-coated, untreated titanium disks. This suggests that decontamination is indispensable for the treatment of peri-implantitis, even if the original biocompatibility cannot be restored.

• Korean Journal of Pharmacognosy
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• v.52 no.3
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• pp.192-201
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• 2021

Dangguisu-san (DGSS) is widely known traditional herbal medicinal formula in Korea for treatment of traumatic injury by traffic accident, ecchymosis, abdominal distension and anti-thrombosis of blood. This study was conducted to develop the simultaneous analyze method using high performance liquid chromatography (HPLC) and examine the effect of anti-inflammatory activity of DGSS-dry extract (DGSS-DE) and DGSS-mix extract powder (DGSS-MEP). Physicochemical characteristics of DGSS-DE and DGSS-MEP showed that there is no significant difference in pH, titratable acidity, total soluble solid content and browning degree except for color value (L, a, b). 15 functional constituents of DGSS were identified and the correlation coefficient values of DGSS-DE and DGSS-MEP were conformed 0.950. Also, DGSS-DE and DGSS-MEP significantly decreased the secretion of nitric oxide (NO), prostaglandin E₂ (PGE₂), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) through inhibited expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-1β, IL-6, and TNF-α. From these result, DGSS-MEP showed similar chemical composition and anti-inflammatory effect to DGSS-DE. Therefore, DGSS-DE and DGSS-MEP may be useful as potential source of drug to prevent inflammation.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.114-118
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• 2011

Even though the carbon paste electrode bound with mineral oil is useful for research about the characteristics of enzymes, it remains far from practical uses because the lack of mechanical hardness limits its practical use. When the rubber liquefied in toluene was used as a binder of carbon powder in lab, it is confirmed that the mechanical robustness of the electrode is guaranteed. In order to confirm whether it shows quantitative electrochemical behaviors or not, its kinetic parameters, e.g. the symmetry factor (${\alpha}=0.28$), the exchange current density ($i_0=4.06{\mu}A/cm^2$), the capacity of the double layer ($C_d=2.11{\times}10^{-3}F$), the Michaelis constant ($K_M=2.45{\times}10^{-3}M$), and the time constant (${\tau}_B=0.077sec$) were investigated. Our experimental observations prove that the chloroprene rubber is a promising binder for the practical use of a carbon paste electrode.