• Korean Journal of Pharmacognosy
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• v.32 no.3 s.126
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• pp.181-188
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• 2001

During the screening for inhibitors of nitric oxide production in LPS-activated macrophage, RAW 264.7 cells, two coumarins were isolated from chloroform extract of the root of Polygonum cuspidatum. They were identified as decursin (1) and decursinol angelate (2) on the basis of spectroscopic methods. The $IC_{50}$ values of these compounds on NO production were $0.76\;{\mu}M$ (1) and $2.6\;{\mu}M$ (2), respectively. However, the iNOS activity was not inhibited by treatment with these compounds. Their inhibitory effect on NO production seems to result from the suppression of iNOS induction through the suppression of NF-kB activity.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.538-544
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• 1989

The increase of B-type hydrogen bonding character between the hydrogen atom($H{\gamma}$) of methylene group in 1-(phenoxymethyl)benzotriazole (1) and 1-(thiophenoxymetyl)benzotriazole (2) derivatives, and solvents was caused by some factors such as;electron withdrawing strength (${\rho} > 0$) of X-substituent; local diamagnetic effect by Y atom (Y = O(1) > S(2)) with adjacent methylene group; and solvent polarity parameter ($E_T$ = Kcal/mol; acetone; 42.2 > chloroform; 39.0). From the basis on the findings, linear free energy relationship (LFER) components on the substituent chemical shift of methylene group ($CH_2-SCS$) in (1) exhibited a tendency that resonance(R)-effect was much larger than field(F) (or inductive(I))-effect in acetone and that the electrical effects were depend upon the solvent.

• The Korean Journal of Food And Nutrition
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• v.14 no.1
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• pp.10-14
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• 2001

The volatile components of umbelliferous herbs having a characteristic spicy aroma were investigated. The essential oils of herbs were isolated by simultaneous steam distillation and extraction and the volatile components were identified by capillary GC and GC/MS. Forty-nine volatile compounds were identified from the herbs. The major compounds of chervil (Anthricus cerefolium) leaf oil were methyl chavicol, 1-allyl-2,4-dimethoxy benzene, and of coriander (Coriandrum sativum) leaf oil were ${\beta}$-sesquiphellan drene, germacrene B, nerolidol, selinene-4-ol, and of coriander seed oil were linalool, decanal, ${\gamma}$-terpinene, $\rho$-cymene.

• Communications of the Korean Mathematical Society
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• v.28 no.3
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• pp.487-500
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• 2013

In this paper we provide a brief introduction to the continuity of approximate point spectrum on the algebra B(X), using basic properties of Fredholm operators and the SVEP condition. Also, we give an example showing that in general it not holds that if the spectrum is continuous an operator T, then for each ${\lambda}{\in}{\sigma}_{s-F}(T){\setminus}\overline{{\rho}^{\pm}_{s-F}(T)}$ and ${\in}$ > 0, the ball $B({\lambda},{\in})$ contains a component of ${\sigma}_{s-F}(T)$, contrary to what has been announced in [J. B. Conway and B. B. Morrel, Operators that are points of spectral continuity II, Integral Equations Operator Theory 4 (1981), 459-503] page 462.

• Journal of the Korean Magnetic Resonance Society
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• v.17 no.2
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• pp.86-91
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• 2013

Detailed information about the structural nature of three-coordinate borons in ${\beta}-BaB_2O_4$ is obtained through $^{11}B$ MAS NMR and $^{11}B$ single-crystal NMR. The three-coordinate $BO_3$ of the two borons B(1) and B(2) in ${\beta}-BaB_2O_4$ were distinguished. The spin-lattice relaxation time in the laboratory frame $T_1$ for B(1) and B(2) slowly decreases with increasing temperature, whereas the spin-lattice relaxation time in the rotating frame $T_{1{\rho}}$ for B(1) and B(2), which differs from $T_1$, is nearly constant. The B(1) and B(2) of the two types were distinguished by $^{11}B$ MAS NMR and $^{11}B$ single-crystal NMR.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.446-452
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• 1992

The rates of hydrolysis of aryl phenylacetates have been measured in the presence of piperidine in 80% acetonitrile-20% water(v/v). For the electron withdrawing substituents of leaving group, the hydrolysis is catalyzed by a general base and the Hammett $\rho_{LG}$ and Bronsted value $\beta$ are 5.28 and -2.72 at $30^{\circ}C$, respectively. These high senstivities of Hammett and Bronsted values are $E1_{C}B$ mechanism. But in the electron donating ones, the hydrolysis is catalyzed by a specific base and $B_{AC}2 mechanism is predominated. $pK_{SH}'s of phenylacetic acid ester and rate constants of hydrolysis $k_1$, $k_{-1)$, $k_2$ were calculated.

• Advances in Computational Design
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• v.3 no.1
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• pp.49-69
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• 2018

This paper shows an optimal design for reinforced concrete rectangular combined footings based on a criterion of minimum cost. The classical design method for reinforced concrete rectangular combined footings is: First, a dimension is proposed that should comply with the allowable stresses (Minimum stress should be equal or greater than zero, and maximum stress must be equal or less than the allowable capacity withstand by the soil); subsequently, the effective depth is obtained due to the maximum moment and this effective depth is checked against the bending shear and the punching shear until, it complies with these conditions, and then the steel reinforcement is obtained, but this is not guaranteed that obtained cost is a minimum cost. A numerical experimentation shows the model capability to estimate the minimum cost design of the materials used for a rectangular combined footing that supports two columns under an axial load and moments in two directions at each column in accordance to the building code requirements for structural concrete and commentary (ACI 318S-14). Numerical experimentation is developed by modifying the values of the rectangular combined footing to from "d" (Effective depth), "b" (Short dimension), "a" (Greater dimension), "${\rho}_{P1}$" (Ratio of reinforcement steel under column 1), "${\rho}_{P2}$" (Ratio of reinforcement steel under column 2), "${\rho}_{yLB}$" (Ratio of longitudinal reinforcement steel in the bottom), "${\rho}_{yLT}$" (Ratio of longitudinal reinforcement steel at the top). Results show that the optimal design is more economical and more precise with respect to the classical design. Therefore, the optimal design presented in this paper should be used to obtain the minimum cost design for reinforced concrete rectangular combined footings.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.284-292
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• 1984

This paper aims to predict the substituent and Lewis acid catalysis effect or reactivity on the regioselectivity of (4+2) cycloaddition reaction of the substituted-E-arene-diazocyanides and nitrosobenzenes. Frontier orbital theory (FMO) has been applied to thermal and catalyzed Diels-Alder reaction by means of CNDO/2 and EHT-SPD methods. It has been found that: (1) The above reaction is positive rho(${\rho}$) values in Hammett equation, so it takes normal electron demand reaction, and four-frontier orbitals and Anh methods are identical with experimental major regioisomer.(2) When electron withdrawing radicals are substituted HOMO and LUMO energies of dienophiles are reduced, and the reactivity is increased. (3) The major regioisomer is predicted as B type, as the Lewis acid makes complexes of dienophile, and polaries LUMO coefficients of dienophile in an opposite way. (4) The linear correlation of Hammett is indicated in the graph of stabilized energies(${\Delta}$E) and sigma(${\sigma}$).

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.589-592
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• 1999

This paper is experimental study on the flexural strength and ductility capacity of reinforced high-strength concrete beams using fly ash artificial lightweight concrete beams and five reinforced high-strength normal concrete beams with different tensile reinforcement ratio were tested to investigate their behavior. Test result show that the ratio of flexural strength between experimetal results and those by ACI code decrease as the compressive strength of concrete increase. Also, The reinforced concrete beams behave more brittly than those with equal reinforcement ratio($\rho$/$\rho$b) as the compressive strength of concrete increase.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.513-518
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• 1998

In general, flexural strength and ductility of reinforced concrete beam with stirrup depend on the compressive strength of concrete and longitudinal steel ratio. In this study, nine reinforced high strength lightweight concrete beams and three reinforced normalweight concrete beams with stirrup were tested to investigate their behavior and to determine their ultimate moment capacity. The variable were strength of concrete (400, 500kg/$\textrm{cm}^2$) and the ratio of tensile steel content to the ratio of the balanced steel content(0.22<$\rho$/$$\rho$_b$<0.56). Test results are presented in terms of load-deflection behavior, ductility index, and cracking patterns.