• Korean Journal of Plant Resources
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• v.7 no.1
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• pp.77-87
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• 1994

The isolation and structure elucidation Of five new oligo-nicotinated sesquiterpene polyesters with a dihydroagarofuran core from Maytenus ilicifolia, named cangorins F, G,H,1 and J [1-5], is described. The strurtures of these compounds, which possessed nicotinyl,benroyl, and areryl groups as esterifying moieties, were elucidaied by $^IH- and ^{13}C$-nmrspectroscopic studies, inrlusive of hereronuclear correlation, long-range correlation, and nOespectra, along with mass and cd spectral dara, and the X-ray crystallographic analysis of 1.

• Archives of Pharmacal Research
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• v.17 no.3
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• pp.170-174
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• 1994

We have synthesized various 6-substituted 2-oxo-purine nucleosides from key intemediate, 6-[(4-methylphenylthio)-2-oxo-9(2, 3, 5tri-o-acetyl-$\beta$-D-ribofuanoslyl)]-2, 3- dihydropurine in relatively high yields by one step nucleophilic substitution. Various isoguanosine, xanthosine analogs and other 2-oxo-purine nucleosides containing nitrogen, sulfur and oxygen at C-6 of purine base were easily obtained by this method. The structures of the products were established on the basis of their spectral data studies. And cytotoxicity of resulting synthetic 6-substituted-2-oxo-purine nucleosides against some tumor cell-lines was examined. $Ed_{50}$ values of these synthetic compounds were above $100\;{\mu}g/ml$ except isoguanosine, $N^6$-methyl isoguanosine and thioxanthosine analogs.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.423-428
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• 1998

This paper studies the regional identifiability of spatially-varying parameters in distributed parameter systems of hyperbolic type. Let Ω be a bounded domain of R$^n$and let Ωo be a subregion of the closed domain Ω. The distributed parameter systems having unknown parameters defined on Ω are described by the second order evolution equations in the filbert space L$^2$(Ω) and the observations are made on the subregion Ωo ⊂ Ω. The regional identifiability is formulated as the uniqueness of parameters by the identity of solutions on the subregion. Several regional identifiability results of the spatially-varying parameters of hyperbolic distributed parameter systems are established by means of the Riesz spectral representations.

• Wind and Structures
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• v.3 no.1
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• pp.1-10
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• 2000

Recently, an efficient and practical method has been developed for the generation of univariate non-Gaussian wind pressure time histories on low building roofs; this methodology requires intermittent exponential random numbers for the simulation. On the other hand, the conventional spectral representation scheme with random phase is found suitable for the generation of univariate Gaussian wind pressure time histories on low building roofs; this simulation scheme requires uniform random numbers. The dependency of these simulation methodologies on the random number generator is one of the items affecting the accuracy of the simultion result; therefore, an attempt has been made to investigate the issue. This note presents the observed sensitivity of random number sets in repetitive simulations of Gaussian and non-Gaussian wind pressures.

• Earthquakes and Structures
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• v.9 no.5
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• pp.1115-1132
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• 2015

The study considers earthquake shake table testing of bending-torsion coupled structures under multi-component stationary random earthquake excitations. An experimental procedure to arrive at the optimal excitation cross-power spectral density (psd) functions which maximize/minimize the steady state variance of a chosen response variable is proposed. These optimal functions are shown to be derivable in terms of a set of system frequency response functions which could be measured experimentally without necessitating an idealized mathematical model to be postulated for the structure under study. The relationship between these optimized cross-psd functions to the most favourable/least favourable angle of incidence of seismic waves on the structure is noted. The optimal functions are also shown to be system dependent, mathematically the sharpest, and correspond to neither fully correlated motions nor independent motions. The proposed experimental procedure is demonstrated through shake table studies on two laboratory scale building frame models.

• YAKHAK HOEJI
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• v.30 no.1
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• pp.1-7
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• 1986

The alkaloid components in the root of Codonopsis lanceolata were studied. From the ether soluble alkaloid fraction, four $\beta$-carboline alkaloids were isolated in crystalline state by chromatographic purification process; comp. I mp $178^{\circ}$, isolated yield 4.5$\times$$10^{-5}%$, comp. II mp $166^{\circ}$, 6.0$\times$$10^{-5}%$, comp. III mp $164^{\circ}$, 1.8$\times$$10^{-4}%$ and comp. IV mp $197^{\circ}$, 3.5$\times$$10^{-5}%$. They were identified by spectral analysis and by total synthesis as being a new component $N_9$-formylharman, and already known components in other plant 1-carbomethoxy-$\beta$-carboline, perlolyrine and norharman.

• YAKHAK HOEJI
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• v.37 no.4
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• pp.325-330
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• 1993

Four flavonoide glycosides and (-)-Epicatechin were isolated from the aqueous extracts of dried whole part of Lysimachia clethroides Duby(Primulaceae). They were 3-0-Methyl-quercetin-7-0-[$\alpha$-L- rhamnopyranosyl (1-2) glucopyranoside], Quercetin-3-0-$\beta$-D-glucopyranoside, Kaempferol-3-0-$\beta$-D-glucopyranoside, Kaempferol-3-0-[$\alpha$-L-rhamnopyranosyl (1-6)-$\beta$-D-glucopyranoside] and (-)-Epicatechin. 3-0-[$\alpha$-L-rhamnopyranosyl (1-6)-$\beta$-D-glucopyranoside]and (-)-Epicatechin. 3-0-Methyl-quercetin-7-0-[$\alpha$-L-rhamnopyranosyl (1-2)-$\beta$-D-glucopyranoside] and (-)-Epicatechin were first isolated from this plant. Their structures were elucidated by spectral analysis [$^{1}$H-, $^{13}C-$ NMR, $^{1}$H-$^{1}$H-COSY, DEPT-analysis, HMQC(Heteronuclear multiple quantum coherence), FAB-MS].

• Korean Journal of Microbiology
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• v.26 no.1
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• pp.44-51
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• 1988

The intracellular free radicals produced at different stages of cell cycle of Saccharomyces cerevisiae ATCC 24858 were investigated by means of electron spin resonance(ESR) spectroscopy. The synchronized cells by repeated starvation and refeeding revealed different ESR spectral pattern compared to that of asynchronized cells. Each spectrum centered at g=2.005, which indicates free radicals. The relative spin concentration was maximat at the end of DNA increase. The variation of the relative spin concentration at each distinct stage of the cell cycle was evaluated in relation to ascorbate concentration, L-galactonolactone oxidase activity, and ascorbate oxidase activity. The highest activities of L-galactonolactone oxidase and ascorbate oxidase were detected just before and at the maximum of relative spin concentration, respectively. And ascorbate concentration fluctuated through each stage of cell cycle with the changes of relative spin concentration, L-galactonolactone oxidase activity, and ascorbate oxidase activity. Thus it is suggested that intracellular free radicals should be related to cell cycle, interacted with ascorbate, and may play an important role in the cell cycle of Saccharomyces cerevisiae.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.381-384
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• 2006

In order to evaluate the seismic performance of a reinforced concrete building structure, four different analyses are carried out. Firstly, conventional pushover analysis with code-specified inverted triangular load pattern is conducted. Secondly, the pushover analysis with uniform load pattern is performed. Thirdly, adaptive pushover analyses with spectral amplification for both EC 8 artificial and Northridge earthquake are carried out. Lastly, incremental dynamic analyses under a number of scaled PGA for both EC 8 artificial and Northridge earthquake record are performed. Comparative studies demonstrate that the adaptive pushover analysis may be able to explain the response characteristics that conventional pushover analysis with fixed load distribution fails to capture.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.257-266
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• 2006

The powerful benefits of multi-antenna systems can be obtained by cooperative communications among users in multiple access environments without the need for physical arrays. This paper studies a novel cooperative signaling strategy that achieves high performance and low implementation complexity for synchronous code division multiple access (CDMA) wireless mobile networks. The validity of the proposed strategy under slow flat Rayleigh fading channel plus additive white Gaussian noise (AWGN) is verified through closed-form error probability expressions and MonteCarlo simulations. A variety of analytical results reveal that the new cooperative strategy significantly outperforms direct transmission subject to the same spectral efficiency and transmit power constraint.