• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.18-24
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• 2013

This study was conducted to recycle fly ash containing an abundance of CaO generated from combustion in a circulating layer as a carbon storage medium. The study utilized XRD, TG-DTA and XRF analyses during the hydration of fly ash and identified calcium substances within fly ash that could be used in a carbonation process. $Ca^{2+}$ ions in the calcium substances were easily converted to hydrates. A carbonation experiment was done, which used the method of $CO_2$ gas injection to produce suspensions by mixing fly ash with distilled water. The results were analyzed using TG-DTA, XRD, and pH meter measurements. The study was able to verify that the reaction was completed at a $CO_2$ flow rate of 300cc/min approximately 30 minutes after an injection into a solution with a solid-liquid ratio of 1 : 10 of fly ash and distilled water. Moreover, the stirring time of the suspensions did not influence the reaction, and the reaction time was found to diminish as the portion of the fly ash became smaller. Thus, this study produced carbon storage fly ash having a $CO_2$ storage rate of about 71% through the utilization of the CaO content contained within fly ash.

• The Journal of Internal Korean Medicine
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• v.39 no.3
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• pp.313-322
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• 2018

Objectives: Wild ginseng pharmacopuncture is widely used in oriental medicine. However, there is no standard method for efficiently extracting the active ingredient. In this study, in order to determine an efficient extraction method, wild ginseng was extracted by the distillation and 70% ethanol reflux methods, respectively. In comparing each extract, the index compounds were analyzed, and antioxidant activity was measured. Methods: The index compounds, ginsenoside Rg1 and ginsenoside Rb1, were detected using high performance liquid chromatography (HPLC). Antioxidative activities of total phenolic compounds, DPPH (${\alpha}$, ${\alpha}$-diphenyl-${\beta}$-picrylhydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) and FRAP (ferric reducing antioxidant power) were measured to compare their bioactivities. Since saponin is known to be hemolytic, the hemolytic activity of each extract was compared. Results: The index compounds were analyzed. Nothing was detected in the wild ginseng distilled extracts (WGDE). In the wild ginseng 70% ethanol reflux extracts (WGEE), ginsenoside Rg1 was 3.66 mg/g, and ginsenoside Rb1 was 16.70 mg/g. WGEE showed higher levels than WGDE in all antioxidative activities. In the hemolytic test, the extracts showed almost no toxicity, but WGEE showed lower toxicity than WGDE. Conclusions: In this study, it was concluded that WGEE is more advantageous than WGDE in the detection of index compounds and bioactivity. However, additional studies of additional extraction methods and other bioactivity tests are needed.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.96-104
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• 2015

Fischer Tropsch reaction is one of the interesting topic for renewable and clean energy. Polymerization of carbon monoxide or carbon dioxide with hydrogen over metal supported catalyst can produce long chain hydrocarbons. Synthetic liquid hydrocarbons are promising alternative to fossil fuels. This research work has been focused on the synthesis of Fe based catalyst for Fischer Tropsch reaction. Mesoporous silica (MS) support prepared by a precipitation method using two different washing solution, distilled water (DW) and acid in ethanol solution (ET), and different calcination temperature. Then, Fe/MS was prepared by an incipient wetness impregnation method. All of samples were systematically characterized using various physical and chemical techniques. TEM and XRD analysis were used to ensure that the cubic Ia3d mesostructure is stable after calcination. FTIR spectra are useful to ascertain the existence of template in the support. TPR studies were also used to understand the nature of Fe species and their reducibility. The results reveal that washing the support with distilled water and calcination at $550^{\circ}C$ can efficiently remove the triblock copolymer templates. The existence of template in the support affects the textural properties of all catalyst investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.333-333
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• 2011

We have investigated the breakdown properties in liquids by high voltage pulse system. High voltage pulse power system is consisted of the Marx-generator with two capacitors (0.5 ${\mu}F$, withstanding voltage is 40 kV), to which the charging voltage can be applied to maximum 30 kV DC, spark gap switch and charging resistor of 20 $M{\Omega}$. We have made use of tungsten pin electrodes of anode-cathode (A-K), which are immersed into the liquids. The breakdown voltage and current signals are measured by high voltage probe (Tektronix P6015A) and current monitor (IPC CM-1.S). Especially the high speed breakdown or plasma propagation characteristics in the pulsed A-K gap have been investigated by using the high speed ICCD camera. We have measured the electron temperature through the Boltzmann plot method from the breakdown spectrums. Here the A-K gap has been changed by 1 mm, 2 mm, and 3 mm. The used liquids are distilled water and solution of salt (0.9 %). The output voltage and current signals at breakdown in distilled water are shown to be bigger than those in saline solution. The breakdown voltage and current characteristics in liquids will be discussed in accordance with A-K gap distances. It is also found that the electron temperatures and plasma densities in liquids are decreased in conformity with A-K gap.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.259-267
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• 1998

For more than two decades, many investigators have tried a variety of methods for delivering antimicrobial agents to the oral cavity with the objective of eliminating mutans streptococci. In the belief that the effectiveness of chemotherapy might be improved by a more effective delivery system, the intention of the present study was to exploit a new drug delivery system delivering chlorhexidine to the oral cavity. The vehicle delivering chlorhexidine tested in this study was self-curing acrylic resin(polymethyl methacrylate). The powder of the acrylic resin was polymerized with the 5 different liquid preparations, in which $Chlorzoin^{(R)}$ was mixed with five different monomer/Chlorzoin ratios immediately prior to the polymerization, in a stainless steel mold ($40mm{\times}40mm{\times}2mm$). A total of 50 cured resin specimens were divided into 5 groups according to the different monomer preparations. Every specimen was soaked in an airtight container filled with distilled water (100 ml) and then kept in an incubator at $37^{\circ}C$. The solutions (0.8 ml) were collected from the container at every 24 hours, and the amount of released chlorhexidine in the solutions was measured in an ultraviolet spectrophotometer at 250nm. The container was refilled with distilled water every after measurement. This procedure was repeated for 14 days. It was found that chlorhexidine was continuously released from all of the 50 specimens during the experimental period. And it was noted that the pattern of chlorhexidine release was a type of sustained-release preparation, that is, the amount of the released chlorhexidine at the first day in all 5 groups was high (p<0.0001), and then the release was decreased during the rest of the experimental period (p<0.001).

• YAKHAK HOEJI
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• v.60 no.3
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• pp.112-117
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• 2016

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of caffeine in forensic aqueous sample. The centrifuged sample ($100{\mu}l$) was diluted 50-fold with distilled water. The diluted sample ($400{\mu}l$) was then diluted further with $200{\mu}l$ of 0.1% formic acid solution and $400{\mu}l$ of acetonitrile containing 500 ng of caffeine-(3-methyl-$^{13}C_3$) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 ($100mm{\times}2.1mm$ i.d., $3.5{\mu}m$) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve with the coefficients of determination ($r^2=0.9983$). The lower limit of quantification was $25ng/ml$ for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions were not more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from -6.8 to 4.5%, respectively. The suitability of the method was examined by analyzing unknown forensic aqueous samples.

• Journal of dental hygiene science
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• v.22 no.3
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• pp.139-147
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• 2022

Background: Temporary crown resins are used prior to prosthesis placement, indicating the importance of aesthetics. The aim of this study was evaluate the color stability of various staining solutions according to the color of temporary crown resins using VITA Easyshade^Ⓡ V. Methods: The temporary crowns used were the powder-liquid type and included four shades. A total of 36 specimens were fabricated in the form of disks with a diameter of 1.8 mm and a depth of 2 mm. They were divided into four groups of nine each, and staining was performed for seven days by precipitation in 3 mL of three staining solutions composed of distilled water, black coffee, and red wine. Color and color stability evaluations were performed by a trained examiner using a digital spectrophotometer (VITA Easyshade^Ⓡ V). Color stability was analyzed using the ΔE value. Results: Because of the color stability evaluation using the ΔE value, the difference between three and seven days was significant in the specimen I and III groups (p<0.05). Further, post hoc analysis showed that the ΔE value of red wine was significant, indicating that the color stability in red wine was low. The ΔE values in group II between days three and seven were statistically significant (p<0.05). Post hoc analysis showed that distilled water, coffee, and wine had the highest ΔE values on day three. On day seven, the ΔE value for wine was significant, and the color stability was low. There was no significant difference in group IV according to the staining period and staining solution; therefore, color stability was high (p>0.05). Conclusion: This study showed that most temporary resin restorations exhibited color stability in the staining solution. The darker the color of the temporary resin restoration, the higher the color stability against extrinsic staining.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.8
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• pp.973-978
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• 2006

This study was conducted to investigate the solubility, antioxidative and antimicrobial activity of the freeze dried chitosan-ascorbate (CAs) and chitosan-acetate (CAc). In the results of solubility, CAs was soluble over 0.5% in distilled water, vinegar, green tea, soju (distilled liquor), beer and red wine, while it was not soluble in soy sauce, soy milk, milk, orange juice, coffee, sesame oil, soy milk and soybean oil. The solubility of CAc in the liquid foods was similar to those of CAs, but it was soluble less than 0.1% in beer, and formed curd in red wine. Electron donating activity, antioxidative activity and SOD activity of CAs were 48.2, 90.6 and 67.5%, respectively, while the activities of the CAc were 0, 40.0 and 10.0%, respectively. The minimal inhibitory concentrations of CAs and CAc were $200\;{\mu}g/disc$ against Bacillus circulans, Bacillus brevis, Bacillus licheniformis, Bacillus arabitane and Bacillus sterothermophillus, $400\;{\mu}g/disc$ against Escherichia coli O157, Listeria monocytogenous, Bacillus cereus and Bacillus subtilis. There was no significant difference in Hunter's L* value between CAs and CAc $(81.95{\sim}82.97)$, but Hunter's a* and b* values of the CAs was higher than those of CAc. While sour and bitter tastes of CAs were lower than those of CAc, there was no significant difference in astringent taste. From these results, it suggested that CAs has more extensive utility in liquid foods with antimicrobial and antioxidant activity as well as sensory quality compared to CAc.

• Journal of the Korean Chemical Society
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• v.62 no.3
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• pp.181-186
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• 2018

Nitrosamines are the nitrosocompounds which are produced by nitrosation reactions of the secondary amine and nitrite, and has been found to be produced through the vulcanization process during the production of rubber products Recently, nitrosamines have been detected in rubber products and become a major topic. Condoms are disposable medical devices, so safety is important because they come into direct contact with the skin and mucous membranes. In this study, we developed an analytical method for nitrosamines in condoms by applying ISO 29941 method. The samples were eluted by distilled water, and target compounds were extracted by liquid-liquid extraction with dichloromethane. And then after concentrated, and quantitatively analyzed by LC-MS/MS. The accuracies of the analytical method were ranged from 85.8 to 108.7%, precisions were lower than 11.5%, and the detection limits were from 0.11 (NDPA and NDBA) to 0.48 (NPYR) ng/mL. Among the 31 condom samples, NDBA was detected from 2 cases by extraction of distilled water, and NDMA were detected from 1 case, NDEA from 4 cases and NDBA from 26 cases by extraction of artificial saliva (pH 4.5). The total amount of nitrosamines in all samples were less than $500{\mu}g/kg$.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.1
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• pp.85-93
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• 2024

In this study, we prepared fractions from Cynanchum paniculatum (C. paniculatum) with ethyl acetate and identified the structure and content of paeonol, an indicator substance. Fractions were obtained by sequential solvent fractions using n-hexane, methylene chloride, ethyl acetate, n-butanol, and distilled water, and showed the highest paeonol content in ethyl acetate (EtOAc). The structure of the ethyl acetate fraction (EA) was confirmed by nuclear magnetic resonance (NMR) and the content was determined by high performance liquid chromatography (HPLC) analysis. The antioxidant activity of EA was tested through its ability to scavenge 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and its ability to inhibit nitric oxide (NO) production in RAW 264.7 cells induced by lipopolysaccharide (LPS) was tested for its ability to inhibit NO production in a concentration-dependent manner. Furthermore, MMP-1 production induced by ultraviolet B (UVB) was decreased in a concentration-dependent manner by the EA, and the ability to produce procollagen type-I was increased in a concentration-dependent manner. In addition, as a result of conducting clinical trials using cosmetic formulations containing EA, the effect of improving wrinkles around the eyes was confirmed. Thus, it is expected that Cynanchum paniculatum can be used as a natural functional cosmetic material with antioxidant and anti-aging effects.