• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.383-387
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• 2007

In this paper the design of the discharge cleaning system for KSTAR vacuum vessel is described. We first discuss about the parameters which are related the efficiency of discharge cleaning. The RG(RF-assisted Glow) discharge which has the ignition and sustain pressure lower than those in the case of DC discharge, thus has the higher efficiency of discharge cleaning. So we adopt the RG discharge, in practical design, for KSTAR discharge cleaning system. For uniformity of the cleaning effect, we plan to install two discharge cleaning systems in A- and I-port of the KSTAR vacuum vessel. The designed system will be adapted for the study of the fuel recycling and of the boronization as well as the discharge cleaning of the KSTAR vacuum vessel.

• Journal of Ginseng Research
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• v.38 no.1
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• pp.47-51
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• 2014

The transformation of ginsenoside Rb1 into a specific minor ginsenoside using Aspergillus niger KCCM 11239, as well as the identification of the transformed products and the pathway via thin layer chromatography and high performance liquid chromatography were evaluated to develop a new biologically active material. The conversion of ginsenoside Rb1 generated Rd, Rg3, Rh2, and compound K although the reaction rates were low due to the low concentration. In enzymatic conversion, all of the ginsenoside Rb1 was converted to ginsenoside Rd and ginsenoside Rg3 after 24 h of incubation. The crude enzyme (b-glucosidase) from A. niger KCCM 11239 hydrolyzed the ${\beta}$-($1{\rightarrow}6$)-glucosidic linkage at the C-20 of ginsenoside Rb1 to generate ginsenoside Rd and ginsenoside Rg3. Our experimental demonstration showing that A. niger KCCM 11239 produces the ginsenoside-hydrolyzing b-glucosidase reflects the feasibility of developing a specific bioconversion process to obtain active minor ginsenosides.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.551-553
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• 1996

A genuine dammarane glycoside, named ginsenoside $Rg_{5}$, has been isolated by repeated column chromatography and preparative HPLC from the MeOH extract of Korean red ginseng (Panax ginseng C.A. Meyer). The chemical structure of ginsenoside$ Rg_{5}$ was determined as $3-O-[{\beta}-D-glucopyranosyl (1{\rightarrow}2)-{\beta}-D-glucopyranosyl]$ dammar-20(22), $24-diene-3{\beta},12{\beta}-diol$ by spectral and chemical methods. The stereostructure of a double bond at C-20(22) of ginsenoside $Rg_{5}$ was characterized as (E) from the chemical shift of C-21 in the $^{13}C-NMR $and a NOESY experiment in the $^{1}H-NMR$.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.528-534
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• 2011

This study was conducted to investigate the changes in saponin content and antioxidant activity of crude ginseng and extruded ginseng by using different solvent extraction methods. Each of the fractions was first extracted by 80% ethanol followed by ether treatment to remove the lipid components. Water soluble components were separated by ethylacetate and water saturated butanol. Four fraction, including 80% ethanol, ethylacetate, butanol and water were obtained from crude and extruded ginsengs to analyze saponin content and antioxidant activity. Saponin content and antioxidant capacity of each of the four fractions were measured by LC/MS analysis and ORAC(Oxygen Radical Absorbance Capacity) assay, respectively. It was found that a major portion of saponin was present in ethyl acetate and water saturated butanol fractions. When extracted by 80% ethanol, ginsenoside Rb1 and Rg1 were mostly found in crude ginseng, while ginsenoside Re and Rb1 were detected in extruded ginseng. Even though Rh1 and Rg3 were found in a very small quantity in crude ginseng, there was a significant quantity of both in extruded ginseng when extracted by 80% ethanol. Similar tendency was also observed in extruded ginseng fraction when extracted with ethyl acetate and butanol. In crude ginseng, the level of Rg1 was the highest among other ginsenosides upon extraction by ethyl acetate, while Rh1 and Rg3 were predominantly found by employing similar solvent extraction in the extruded ginseng. Also, Rg1, Re and Rb1 were also found in the extruded ginseng with small quantity. Rg1, Re and Rb1 were found in crude ginseng by butanol extraction, while Rb1 and Re were extracted from the extruded ginseng. Overall, there was no difference in the saponin content between crude ginseng and extruded ginseng when extracted by butanol and water, but twice as much of saponin was obtained by 80% ethanol extraction and 6 times more saponin were obtained in ethyl acetate fraction in the extruded ginseng. Antioxidant capacity of crude ginseng as determined by ORAC assay was higher in 80% ethanol(high in many different kinds of biological compounds) and water saturated butanol(high in polar saponin) fractions than the ethyl acetate and water fractions. No difference in antioxidant capacity was observed between crude and extruded ginseng. However, antioxidant capacity of ethyl acetate and water fractions in extruded ginseng was significantly higher than crude ginseng($P$ >0.05). All the fractions in both, crude and extruded ginseng possessed antioxidant capacity and even water fractions that contained almost no saponin had some antioxidant capacity. While determining correlation coefficient between fractions in extruded ginseng by Pearson correlation, it was observed that 80% ethanol fraction was in correlation with ethyl acetate($P$ >0.01) and ethanol($P$ >0.001) and in the case of ethylacetate, correlation was observed only with butanol fraction($P$ >0.05).

• Journal of Ginseng Research
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• v.37 no.3
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• pp.269-272
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• 2013

MGB-20 findings show that the ginseng berry extracts that had been processed with microwave and vinegar for 20 min peaked in the level of ginsenoside Rg2 (2.28%) and Rh1 (1.28%). MGB-1 peaked in the level of ginsenoside Rg3 (1.13%) in the ginseng berry extract processed with microwave and vinegar for 1 min.

• Journal of the Korean Mathematical Society
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• v.38 no.1
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• pp.77-85
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• 2001

If an Azumaya algebra A is a homomorphic image of a finite group ring RG where G is a direct product of subgroups then A can be decomposed into subalgebras A(sub)i which are homomorphic images of subgroup rings of RG. This result is extended to projective Schur algebras, and in this case behaviors of 2-cocycles will play major role. Moreover considering the situation that A is represented by Azumaya group ring RG, we study relationships between the representing groups for A and A(sub)i.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.370-373
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• 2003

The legacy Residential Gateway (RG) which constitutes fixed WAN interfaces and LAN interfaces, is at a disadvantage due to difficult modification of a system. In this paper, we propose the flexible module-based RG on the basis of the RG standardization and demonstrate the prototype system, whose function is verified by the home automation application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3401-3420
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• 2018

Pixel expansion and contrast are two major performance parameters for visual cryptography scheme (VCS), which is a type of secret image sharing. Random Grid (RG) is an alternative approach to solve the pixel expansion problem. Chen and Tsao proposed the first (k, n) RG-based VCS, and then Guo et al., Wu et al., Shyu, and Yan et al. significantly improved the contrast in recent years. However, the investigations on improving the contrast of threshold RG-based VCS are not sufficient. In this paper, we develop a contrast-improved algorithm for (k, n) RG-based VCS. Theoretical analysis and experimental results demonstrate that the proposed algorithm outperformers the previous threshold algorithms with better visual quality and a higher accuracy of contrast.

• Communications of the Korean Mathematical Society
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• v.33 no.4
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• pp.1075-1082
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• 2018

Let R be a commutative ring, G be an Abelian group, and let RG be the group ring. We say that RG is a U-group ring if a is a unit in RG if and only if ${\epsilon}(a)$ is a unit in R. We show that RG is a U-group ring if and only if G is a p-group and $p{\in}J(R)$. We give some properties of U-group rings and investigate some properties of well known rings, such as Hermite rings and rings with stable range, in the presence of U-group rings.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.761-768
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• 2018

In this paper, the performance analysis of a control topology based on the direct output power control (DPC) for robust and inexpensive permanent magnet-assisted synchronous reluctance generator (PMa-SynRG) system is presented. The PMa-SynRG might be coupled to an internal combustion engine running at variable speed. A three-phase PWM rectifier rectifies the generator output and supplies the dc link. A single-phase PWM inverter supplies constant ac voltage at constant frequency to the grid. The overall control algorithm is implemented on a TMS320F2812 digital signal processor board. Simulations results and experimental results verify the operation of the proposed system.