• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.921-925
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• 2000

Characteristics of Pb(Mg, Nb)O$_3$-Pb(Zr, Ti)O$_3$system thick films fabricated by a screen printing method were investigated. The buffer layer were coated with various thickness of Ag-Pd by screen printing to investigate the effect as a diffusion barrier and deposited Pt as a electrode by sputtering on Ag-Pb layer. The printed thick films were burned out at 650$\^{C}$ and sintered at 950$\^{C}$ in O$_2$condition for each 20, 60min after printing with 350mesh screen. The thickness of piezoelectric thick film was 15∼20㎛ and Ag-Pb layer acted as a diffusion barrier above 3㎛ thickness. The PMN-PZT thick films were screen printed on Pt/Ag-Pb(6m) and sintered by 2nd step (650$\^{C}$/20min and 950$\^{C}$/1h) using paste mixed PMN-PZT and binder in the ratio of 70:30, and the remnant polarization of thick film was 9.1$\mu$C/㎠ in this conditions.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
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• pp.163-168
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• 2003

In the present study, the piezoelectricity and polarization of multilayer ceramic actuator, being designed to stack PMN-PZ-PT ceramic layers and Ag-Pd electrode layers alternatively, were investigated under a consideration of geometric factor, the volume ratio of the ceramic to the electrode layers. The actuators were fabricated by tape casting of $0.2Pb(Mg_{1/3}Nb_{2/3)O_3-0.38PbZrO_3-0,42PbTiO_3$ followed by lamination and burnout & co-firing processes. The actuators of $10\times10\times0.6~2\textrm{mm}^3$ in size were formed in a way that $60 ~ 200\mu\textrm{m}$ thick were stacked alternatively with $5\mu\textrm{m}$ thick electrode layer. Increases in polarization and electric field-induced displacement with thickness of the ceramic layer were attributed to change of $90^{\circ}$/$180^{\circ}$ domain ratio, which was affected by interlayer internal stress. The piezoelectricity and actuation behaviors were found to depend upon the volume ratio (or thickness ratio) of ceramic to electrode layers.

• 약학회지
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• 제49권6호
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• pp.490-494
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• 2005

The objective of this study is to provide the basic information for developing a high-value ginseng product using ginseng saponin and prosapogenin. In order to achieve such aim, Ginsenoside compositions of black ginseng (BG) extracts with various solvent conditions were examined by HPLC. The total saponin and the prosapogenin content of 95$\%$ ethyl alcohol extract were higher than that of the either 50$\%$ ethyl alcohol extract or distilled water extract. As a result, the order of the total saponin and the prosapogenin content was 1) 95$\%$ ethyl alcohol,2) 50$\%$ ethyl alcohol,3) the first and second mixture of 95$\%$ ethyl alcohol, distilled water, and 4) distilled water extract. In the case of fine black ginseng (FBG), the first and second mixture extracts of 95$\%$ ethyl alcohol and distilled water were the highest. In addition, the ratio of the protopanaxadiol group and the protopanaxatriol group (PD/PT) showed that the ratio of BG ranged from 0.304 to 0.601, while the ratio of FBG ranged from 1.166 to 1.657.

• Journal of Ginseng Research
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• 제16권1호
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• pp.44-52
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• 1992

This study investigated ginsenosides and tissue characteristics of roots injured by physiological disorder, rusty and rough skin. After separation to cortex and stele parts of healthy, rusty (red) and rough skin roots, respectively, the contents of saponin and ginsenosides were analyzed. And also, the histological and cytological characteristics of cortex and stele parts were investigated. Crude saponin contents were little different among healthy, rusty (red) and rough skin root and ginsenesides as - Rgl, - Re and - Rbl were largely detected both in stele and cortex part. The ratio of PT/PD showed about 1:1 in three kinds of root. In histological study, destoryed cells in epidermis of rusty(red) root, and those in epidermis and exodermis of rough skin root were observed. The cells in cortex of rusty (red) and rough skin root have generally nucleus with unfixed shape, unequal cell wall, large number of vacuole and mitochondris, and unidentified dark substances compared to healthy root. But in cell of stele tissue, most of organellE seems to be normal except a small number of cells in rough skin root.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1681-1690
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• 1998

The aim of this paper is to investigate combustion characteristics of lean premixed mixture stabilized by catalytic surface reaction. The catalytic combustor consisted of a catalyst bed and a thermal combustor. The catalyst bed was made of two stage, Pd catalyst in the first stage and Pt catalyst in the second stage. Auto ignition of lean mixture took place in the thermal combustor. Ignition temperature was about $810{\sim}820^{\circ}C$ at the fuel-air ratio of 1.5~3.0 % and the mixture velocity of 11~18m/sec. The position of flame front in the thermal combustor moved toward back as preheat temperature increased and fuel-air ratio decreased. The f1ame supported by surface reaction was stabilized without any flame stabilizers. NOx emissions from the catalytic combustor were below 2.0 ppm ($O_2$ 15 %) when gas temperature was limited below $1350^{\circ}C$. This result demonstrates that NOx emission from the catalytic combustor is much low comparing with conventional combustors.

• Food Science and Biotechnology
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• 제16권2호
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• pp.281-284
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• 2007

The objective of this research is to provide basic information necessary to differentiate between ginseng (Panax ginseng) grown in woods environments and cultivated ginseng. The ginseng saponin (ginsenoside) contents of Korean woods-grown, 4 year-old cultivated, and 6 year-old cultivated ginsengs were determined via HPLC analysis. The total saponins in the woods-grown ginseng (0.648%) were approximately twice that of the 4 year-old cultivated (0.270%) and the 6 year-old cultivated ginsengs (0.280%). The protopanaxadiols (PD)/protopanaxatriols (PT) ratio of the woods-grown ginseng (3.258%) was higher than that of the 4 year-old cultivated (2.456%) and the 6 year-old cultivated ginsengs (2.183%). The $Rb_1/Rg_1$ ratio of the woods-grown ginseng (10.225%) was also higher than those of the 4 year-old cultivated (3.514%) and the 6 year-old cultivated ginsengs (4.865%).

• Journal of Ginseng Research
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• 제20권2호
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• pp.139-148
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• 1996

This study was designed to examine the effects of red ginseng total saponin and extract on spatial working memory in mice using Morris water maze. Two kinds of red ginseng saponin (No. 1 and No. 2) and three kinds of red ginseng extract (No. 1, No. 2 and No. 3) to have different PD/ PT ratio (No. 1=1.24, No.2=1.47 No.3=2.41) were prepared by mixing the different parts of red ginseng In different ratio. In acute administration of total saponin No. 1 or No. 2, escape time to reach to a hidden platform In a fixed location for training trials was significantly decreased as compared with control group and swimming time in the quadrant that had contained the platform was also significantly increased as compared with control group. In acute treatment of extract No. 1 or 1 No. 2, swimming time in the platformless quadrant was increased dose dependently as compared with control group, especially at dose of 200 mg/kg,bw swimming time was significantly Increased. Oral treatment of extract No. 1 (100 mg/kg, bw) for 7 days produced an increase of swimming time In the platformless quadrant but a decrease of swimming time in No.3-treated group (100 mg/kg, bw). These results show that red ginseng may improve spatial discrimination learning and spatial working memory of mice

• 상하수도학회지
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• 제33권1호
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• pp.31-41
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• 2019

Volatile organic compounds(VOCs) are toxic carcinogenic compounds found in wastewater. VOCs require rapid removal because they are easily volatilized during wastewater treatment. Electrochemical advanced oxidation processes(EAOPs) are considered efficient for VOC removal, based on their fast and versatile anodic electrochemical oxidation of pollutants. Many studies have reported the efficiency of removal of various types of pollutants using different anodes, but few studies have examined volatilization of VOCs during EAOPs. This study examined the removal efficiency for VOCs (chloroform, benzene, trichloroethylene and toluene) by oxidization and volatilization under a static stirred, aerated condition and an EAOP to compare the volatility of each compound. The removal efficiency of the optimum anode was determined by comparing the smallest volatilization ratio and the largest oxidization ratio for four different dimensionally stable anodes(DSA): Pt/Ti, $IrO_2/Ti$, $IrO_2/Ti$, and $IrO_2-Ru-Pd/Ti$. EAOP was operated under same current density ($25mA/cm^2$) and electrolyte concentration (0.05 M, as NaCl). The high volatility of the VOCs resulted in removal of more than 90% within 30 min under aerated conditions. For EAOP, the $IrO_2-Ru/Ti$ anode exhibited the highest VOC removal efficiency, at over 98% in 1 h, and the lowest VOC volatilization (less than 5%). Chloroform was the most recalcitrant VOC due to its high volatility and chemical stability, but it was oxidized 99.2% by $IrO_2-Ru/Ti$, 90.2% by $IrO_2-Ru-Pd/Ti$, 78% by $IrO_2/Ti$, and 75.4% by Pt/Ti anodes The oxidation and volatilization ratios of the VOCs indicate that the $IrO_2-Ru/Ti$ anode has superior electrochemical properties for VOC treatment due to its rapid oxidation process and its prevention of bubbling and volatilization of VOCs.

• Journal of Ginseng Research
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• 제24권4호
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• pp.176-182
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• 2000

홍삼의 물 추출물, 알코올 추출물, 지용성 추출물, 총 사포닌, PD 및 PT 각 홍삼 추출물을 생리식염수에 녹여 50mg/kg/0.1ml용량으로 4주령 수컷 생쥐에게 15일간 경구투여 하여 생쥐 간으로부터 항산화 효소(GPX)의 활성도 변화와 GSH, GSSG 및 MDA의 함량 변화에 미치는 영향을 조사하였다. GPX의 활성도는 PD, PTTS순으로 활성도가 높은 것으로 조사되었으며, 항산화 물질인 환원형 GSH 또한 같은 순으로 증가하는 것으로 사되었다. 한편 GSSG 함량은 지용성 추출물, PD, 알코올 추출물 순으로 감소하는 것으로 조사되었다. 동물조직세포내의 산화환원반응과 해독작용상태의 평가에 중요한 GSSG/total GSH비율은 지용성 추출물, PD, 총 사포닌 순으로 감소하는 것으로 조사되었다. 활성 산소에 의해 생성된 지질과산화의 최종산물인 MDA의 함량은 GSSG/total GSH 비율의 조사 결과와 비슷한 경향을 보였다 이와 같은 결과를 종합하여 볼 때 항산화 효소 활성과 항산화 물질 활성 증대를 강화시키는 홍삼 성분으로는 지용성 추출물, PD 및 총 사포닌인 것으로 조사되었으며, 이러한 성분들이 산화적 손상에 대한 방어기전 향상에 좋은 것으로 생각된다.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1865-1872
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• 2011

This study investigates the sensitivity of a gas sensor to volatile organic compounds (VOCs) at various operating temperatures and catalysts. Nano-sized powdered $WO_3$ prepared by sol-gel and chemical precipitation methods was mixed with various metal oxides. Next, transition metals (Pt, Ru, Pd, and In) were doped on the surface of the mixture. Metal-$WO_3$ thick films were prepared using the screen-printing method. The physical and chemical properties of the films were studied by SEM/EDS, XRD, and BET techniques. The measured sensitivity to VOCs is defined as the ratio ($R_a/R_g$) of resistance ($R_{air}$) of $WO_3$ film in the air to resistance ($R_{gas}$) of $WO_3$ film in a VOCs test gas. The sensitivity and selectivity of the films were tested with various VOCs such as acetaldehyde, formaldehyde, methyl alcohol, and BTEX. The thick $WO_3$ film containing 1 wt % of Ru and 5 wt % of $SnO_2$ showed the best sensitivity and selectivity to acetaldehyde gas at an operating temperature of 300 $^{\circ}C$.