• 한국재료학회지
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• 제28권6호
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• pp.355-360
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• 2018

$LuNbO_4:0.2Yb^{3+},xTm^{3+}$ powders were prepared using a solid-state reaction process. The effects of the amount of Tm on up-conversion(UC) and down-conversion(DC) luminescence properties are investigated. X-ray diffraction patterns confirm that $Yb^{3+}$ and $Tm^{3+}$ ions are successfully incorporated into Lu sites. Under 980 nm excitation, the UC spectra of the powders predominantly exhibit strong near-infrared emission bands that peak at 805 nm, whereas weak 480 nm emission bands are observed as well. The emission bands are assigned to the $^1G_4{\rightarrow}^3H_6$ (480 nm) and 3 $^3H_4{\rightarrow}^3H_6$ (805 nm) transitions of the $Tm^{3+}$ ions via an energy transfer from $Yb^{3+}$ to $Tm^{3+}$; two- and three-photon UC processes are responsible for the 805 and 480 nm emissions, respectively. The DC emission spectra exhibit blue emission ($^1D_2{\rightarrow}^3F_4$) of $Tm^{3+}$ at 458 nm. The amount of Tm affects the emission intensity with the strongest emissions at x = 0.007 and 0.02 for the UC and DC luminescence, respectively. The results demonstrate that $LuNbO_4:Yb^{3+},Tm^{3+}$ phosphors are suitable for bio-applications.

• 약학회지
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• 제49권5호
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• pp.416-421
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• 2005

Cudrania tricuspidata Bereau (Moraceae) have been used for anti-inflammatory, anti-hepatotoxic, anti-hyper­tensive and anti-diabetic activities. In order to investigate the efficacy of antioxidant activity, the bio-activity guided fraction and isolation of Biologically active substance were performed. $H_{2}O,\;30\%,\;60\%,\;100%$ MeOH and acetone fractions were examined on the antioxidant activity by DPPH method. It was shown that $30\%,\;60\%,\;100\%$ MeOH fractions have sig­nificantly antioxidant activity. From $30\%$ MeOH fraction, two dihydroflavonoid glycosides dihydroquercetin 7-O-$\beta$-D-glu­copyranoside (I), dihydrokaempferol 7-O-$\beta$-D-glucopyranoside (V) were isolated and $60\%$ MeOH fraction, six flavonoids including quercetin 3-O-$\alpha$-L-rhamnopyranosyl($1\rightarrow6$)-$\beta$-D-glucopyranoside (II), quercetin 3-O-$\beta$-D-glucopyranoside (III), quercetin 7-O-$\beta$-D-glucopyranoside (IV), kaempferol 3-O-$\alpha$-L-rhamnopyranosyl($1\rightarrow6$)-$\beta$-D-glucopyranoside (VI), kaempferol 3-O-$\beta$-D-glucopyranoside (VII), kaempferol 7-O-$\beta$-D-glucopyranoside (VIII) were isolated. To investigate the antioxidant activities of each compounds, we measured radical scavening activity with DPPH method and anti-lipid per­oxidative efficacy on low density lipoprotein (LDL) with TBARS assay. Four compounds of quercetin glycosides (I, II, III, IV) showed significant antioxidant activity.

• Archives of Pharmacal Research
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• 제20권5호
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• pp.513-515
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• 1997

From the roasted seeds of Cassia tora L., a new naphthopyrone glycoside was isolated and characterized as 10-[${\beta}$-D-glucopyranosyl-$(1{\rightarrow}6)-O-{\beta}-D-$glucopyranosyl)oxy]-5-hydrox y-8-methoxy-2-methyl-4H-naphtho[1, 2-b]pyran-4-one(isorubrofusarin gentiobioside). Along with isorubrofusarin gentiobioside, alaternin and adenosine were isolated and identified.

• Journal of Ginseng Research
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• 제42권4호
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• pp.504-511
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• 2018

Background: The biological activities of ginseng saponins (ginsenosides) are associated with type, number, and position of sugar moieties linked to aglycone skeletons. Deglycosylated minor ginsenosides are known to be more biologically active than major ginsenosides. Accordingly, the deglycosylation of major ginsenosides can provide the multibioactive effects of ginsenosides. The purpose of this study was to transform ginsenoside Rb2, one of the protopanaxadiol-type major ginsenosides, into minor ginsenosides using ${\beta}$-glycosidase (BG-1) purified from Armillaria mellea mycelium. Methods: Ginsenoside Rb2 was hydrolyzed by using BG-1; the hydrolytic properties of Rb2 by BG-1 were also characterized. In addition, the influence of reaction conditions such as reaction time, pH, and temperature, and transformation pathways of Rb2, Rd, F2, compound O (C-O), and C-Y by treatment with BG-1 were investigated. Results: BG-1 first hydrolyzes 3-O-outer ${\beta}$-$\text\tiny{D}$-glucoside of Rb2, then 3-O-${\beta}$-$\text\tiny{D}$-glucoside of C-O into C-Y. C-Y was gradually converted into C-K with a prolonged reaction time, but the pathway of Rb2 ${\rightarrow}$ Rd ${\rightarrow}$ F2 ${\rightarrow}$ C-K was not observed. The optimum reaction conditions for C-Y and C-K formation from Rb2 by BG-1 were pH 4.0-4.5, temperature $45-60^{\circ}C$, and reaction time 72-96 h. Conclusion: ${\beta}$-Glycosidase purified from A. mellea mycelium can be efficiently used to transform Rb2 into C-Y and C-K. To our best knowledge, this is the first result of transformation from Rb2 into C-Y and C-K by basidiomycete mushroom enzyme.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.387-392
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• 2019

$Dy^{3+}$ and $Eu^{3+}$-co-doped $La_2MoO_6$ phosphor thin films were deposited on sapphire substrates by radio-frequency magnetron sputtering at various growth temperatures. The phosphor thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy, ultraviolet-visible spectroscopy, and fluorescence spectrometry. The optical transmittance, absorbance, bandgap, and photoluminescence intensity of the $La_2MoO_6$ phosphor thin films were found to depend on the growth temperature. The XRD patterns demonstrated that all the phosphor thin films, irrespective of growth temperatures, had a tetragonal structure. The phosphor thin film deposited at a growth temperature of $100^{\circ}C$ indicated an average transmittance of 85.3% in the 400~1,100 nm wavelength range and a bandgap energy of 4.31 eV. As the growth temperature increased, the bandgap energy gradually decreased. The emission spectra under ultraviolet excitation at 268 nm exhibited an intense red emission line at 616 nm and a weak emission line at 699 nm due to the $^5D_0{\rightarrow}^7F_2$ and $^5D_0{\rightarrow}^7F_4$ transitions of the $Eu^{3+}$ ions, respectively, and also featured a yellow emission band at 573 nm, resulting from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of the $Dy^{3+}$ ions. The results suggest that $La_2MoO_6$ phosphor thin films can be used as light-emitting layers for inorganic thin film electroluminescent devices.

• 한국재료학회지
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• 제27권6호
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• pp.339-344
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• 2017

A series of $CaNb_2O_6:Dy^{3+}$, $CaNb_2O_6$:$Eu^{3+}$ and $CaNb_2O_6:Dy^{3+}$, $Eu^{3+}$ phosphors were prepared by solid-state reaction process. The effects of activator ions on the structural, morphological and optical properties of the phosphor particles were investigated. XRD patterns showed that all the phosphors had an orthorhombic system with a main (131) diffraction peak. For the $Dy^{3+}$-doped $CaNb_2O_6$ phosphor powders, the excitation spectra consisted of one broad band centered at 267 nm in the range of 210-310 nm and three weak peaks; the main emission band showed an intense yellow band at 575 nm that corresponded to the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$ ions. For the $Eu^{3+}$-doped $CaNb_2O_6$ phosphor, the emission spectra under ultraviolet excitation at 263 nm exhibited one strong reddish-orange band centered at 612 nm and four weak bands at 536, 593, 650, and 705 nm. For the $Dy^{3+}$ and $Eu^{3+}$-codoped $CaNb_2O_6$ phosphor powders, blue and yellow emission bands due to the $^4F_{9/2}{\rightarrow}^6H_{15/2}$ and $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transitions of $Dy^{3+}$ ions and a main reddish-orange emission line at 612 nm resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions were observed. As the concentration of $Eu^{3+}$ ions increased from 1 mol% to 10 mol%, the intensities of the emissions due to $Dy^{3+}$ ions rapidly decreased, while those of the emission bands originating from the $Eu^{3+}$ ions gradually increased, reached maxima at 10 mol%, and then slightly decreased at 15 mol% of $Eu^{3+}$. These results indicate that white light emission can be achieved by modulating the concentrations of the $Eu^{3+}$ ions incorporated into the $Dy^{3+}$-doped $CaNb_2O_6$ host lattice.

• 대한수학회지
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• 제56권5호
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• pp.1355-1370
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• 2019

A curve $X{\subset}\mathbb{P}^r$ has maximal rank if for each $t{\in}\mathbb{N}$ the restriction map $H^0(\mathcal{O}_{\mathbb{P}r}(t)){\rightarrow}H^0(\mathcal{O}_X(t))$ is either injective or surjective. We show that for all integers $d{\geq}r+1$ there are maximal rank, but not arithmetically Cohen-Macaulay, smooth curves $X{\subset}\mathbb{P}^r$ with degree d and genus roughly $d^2/2r$, contrary to the case r = 3, where it was proved that their genus growths at most like $d^{3/2}$ (A. Dolcetti). Nevertheless there is a sector of large genera g, roughly between $d^2/(2r+2)$ and $d^2/2r$, where we prove the existence of smooth curves (even aCM ones) with degree d and genus g, but the only integral and non-degenerate maximal rank curves with degree d and arithmetic genus g are the aCM ones. For some (d, g, r) with high g we prove the existence of reducible non-degenerate maximal rank and non aCM curves $X{\subset}\mathbb{P}^r$ with degree d and arithmetic genus g, while (d, g, r) is not realized by non-degenerate maximal rank and non aCM integral curves.

• 약학회지
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• 제40권4호
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• pp.394-399
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• 1996

As a series of the studies on the specific and indigenous plants of Mt. Halla, the constituents from stem of Rhamnus taquetii (Rhamnaceae) were investigated. From the water fraction of the MeOH extract, a new flavonol glycoside, kaempferide-3-O-${\alpha}$-L-rhamnopyranosyl(1->3)-${\alpha}$-L-rhamnopyranosyl(1-6)-${\beta}$-D-galactopyranoside, was isolated with three known compounds, quercetin, quercetin-3-methylether, kaempferol, by column chromatographic separation using Amberlite XAD-2, ODS-gel and Sephadex LH-20 and elucidated physico-chemical evidences($^1H-NMR,\;^{13}C-NMR$,IR, EI-Mass, FAB-Mass, and G.C.),respectively.

• 천문학회보
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• 제38권1호
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• pp.50.1-50.1
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• 2013

As part of the DIGIT key program, we observed GSS30-IRS1, a Class I object located in Ophiuchus (d=125 pc), with Herschel-PACS. More than 70 lines were detected: CO lines of $J=14{\rightarrow}13$ to $41{\rightarrow}40$, several $H_2O$ lines of Eu=100 to 1500 K, 16 OH lines, and two atomic [OI] lines at 63 and 145 ${\mu}m$. All lines, except for [OI], were detected only at the central spaxel of $9.4^{\prime\prime}{\times}9.4^{\prime\prime}$ while the [OI] emission is extended along the NE-SW direction. One interesting feature in GSS30-IRS1 is that the continuum is extended beyond PSF, unlike the line emission. For detail analysis, we apply the non-LTE LVG model, RADEX as well as simple rotational diagrams to the detected line fluxes. We will discuss about the physical conditions around GSS30-IRS1, learned by the line flux analysis.

• 한국세라믹학회지
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• 제38권9호
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• pp.806-810
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• 2001

$La_{2/3}TiO_3$, $La_2Ti_2O_7$는 유전성을 갖는 특징으로 인해 여러 분야에 이용되고 있다. 본 연구는 perovskite 구조의 $La_{2/3}TiO_3$와 pyrochlore 구조의 $La_2Ti_2O_7$를 모체로 하여 $Al^{3+},\;Pr^{3+}$가 첨가된 형광체의 발광 특성을 알아보고자 하였다. 두 구조 모두 $Pr^{3+}의\;^1D_2{\rightarrow}^3H_4$ 전이에 의한 적색 발광을 나타내었다. 본 연구에서는 perovskite 구조의 $La_{2/3}TiO_3$:Pr 형광체의 에너지 전이 과정과 그 임계거리에 대한 조를 통해 에너지 전달체로서의 $Al^{3+}$의 역할을 제시하였다. 또한, perovskite 구조의 $La_{2/3}TiO_3$와 pyrochlore 구조의 $La_2Ti_2O_7$ 사이의 발광특성 차이를 알아보기 위해서 trap-involved process와 charge transfer band를 조사하였다.