• Journal of information and communication convergence engineering
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• v.7 no.1
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• pp.72-77
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• 2009

Three different procedures for adding Pd compounds to $SnO_2$ particles have been investigated. These processes are: (1) coprecipitation; (2) dried powder impregnation; and (3) calcined powder impregnation. The microstructures of $SnO_2$ particles have been analyzed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). In the coprecipitaion method, the process does not restrain the growth of $SnO_2$ particles and it forms huge agglomerates. In the dried powder impregnation method, the process restrains the growth of $SnO_2$ particles and the surfaces of the agglomerates have many minute pores. In the calcined powder impregnation method, the process restrains the growth of $SnO_2$ particles further and the agglomerates have a lot more minute pores. The sensitivity ($S=R_{air}/R_{gas}$) of the $SnO_2$ gas sensor made by the calcined powder impregnation process shows the highest value (S = 21.5 at 5350 ppm of $C_3H_8$) and the sensor also indicates the lowest operating temperature of around $410^{\circ}C$. It is believed that the best result is caused by the plenty of minute pores at the surface of the microstructure and by the catalyst Pd that is dispersed at the surface rather than the inside of the agglomerate. Schematic models of Pd distribution in and on the three different $SnO_2$ particles are presented.

• Journal of Ginseng Research
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• v.33 no.4
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• pp.343-348
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• 2009

This study was conducted to produce a new red ginseng by steaming ginseng using a new pre-treatment method, so as to develop ginseng products with improved flavor and thereby expand ginseng's consumer base. The color parameters (Hunter value), free sugar contents, and ginsenoside contents of the powder from the dried red ginseng, and the sensory test of the semi-dried red ginseng and the decoction from the dried red ginseng, were measured to investigate the effect of acid (ascorbic acid or citric acid) impregnation pre-treatment on red ginseng. The powder from the acid-pretreated red ginseng became lighter and more yellow than the red ginseng that was not pre-treated, but the redness (avalue) of the powder from the acid-pre-treated red ginseng increased. The ginsenoside contents of $Rg_2+Rh_1$ and $Rg_3$ increased with the acid treatment. There was a significant difference in the color and sweetness of the semi-dried acidtreated and non-treated red ginsengs in the sensory test. As the results of the sensory test were expressed in the hedonic scale, however, there were significant differences in the degrees of bitterness, astringency, sourness, odor, and color of the red ginseng decollation. Especially, the acid-treated red ginseng extract tasted less bitter, which shows the potential of new red ginseng products with improved ginseng flavor.