• Journal of The Korean Astronomical Society
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• v.11 no.1
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• pp.1-30
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• 1978

The four dimensional classification of globular dusters with the parameters, Z, Y, age and HB type is presented defining two new parameters. $(B-V)_{1/2}\;and\;S_{3/2}$ which are shown to be tightly correlated with Kinman's spectral types and the helium abundances obtained from the R-method, respectively. The Z- and Y- abundances are derived from $(B-V)_{1/2}\;and\;S_{3/2}$, respectively, and the latter parameters determine the age class of clusters with help of Dickens' HB type, which is a function of Z. Y and age. For the examined forty two globular clusters the computed range at Z and Y are $1.5{\times}10^{-4}{\leq}Z{\leq}4.5{\times}10^{-2}\;and\;0.23<Y{\leq}0.41$. The age difference between the oldest (HB type 1) and the youngest (HB type 7) clusters is roughly estimated to be $2-4{\times}10^9$ years. Using these four parameters the known anomalous C-M diagrams seem to be reasonably interpreted without taking into account some complicate parameters such as unusually overabundant heavy elements, mass loss and mass spread, etc. The four dimensional scheme strongly suggests the slow successive collapses of the proto-Galaxy rather than a single fast collapse, and by this slow collapse model the inversion of chemical abundance gradient in the Galaxy can be explained. It is also shown that the clump position along the RGB near the HB level removes down to the fainter magnitude as the Z(Y)- abundance increases (decreases).

• Journal of the Korean Society of Tobacco Science
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• v.25 no.1
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• pp.39-46
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• 2003

The essential oils from Burley 21 tobacco was isolated by using the SDE (Simultaneous Distillation & Extraction) apparatus coupled with gas chromatography and mass spectrometry analysis. Burley 21 tobaccos were divided and collected by six stages at intervals of five days during air-curing process. Air curing was conducted with horizontal hanging method in greenhouse settled by shading materials. 55 components were identified by comparisons of retention indices and mass spectral data, including 22 hydrocarbons, 6 alcohols, 3 aldehydes, 9 ketones and 15 miscellaneous compounds. Neophytadiene was the major components of the oils and almost all hydrocarbons were gradually decreased during air-curing process. Most of alcohols were also diminished, on the contrary, 1-pentanol and benzyl alcohol among them were increased. Aldehydes and ketones were increased during air-curing and especially, the concentrations of solanone, $\beta$-damascone, $\beta$-damascenone and megastigmatrienones were much increased. Indole level of miscellaneous compounds were continuously increased during air-curing of Burley 21 tobacco.

• Analytical Science and Technology
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• v.37 no.4
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• pp.230-238
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• 2024

This study evaluates a method for quantifying selenium (Se) concentration in soil using inductively coupled plasma mass spectrometry (ICP-MS), with oxygen as a reaction gas. This approach addresses the challenge of detecting low levels of Se in complex soil matrices and aims to effectively minimize interference problems typically associated with argon plasma in traditional ICP-MS analyses. The analytical method utilizes conditions optimized for minimizing spectral interference and were validated by linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ). The method demonstrated good linearity, high accuracy (90-97 %), and remarkable sensitivity, achieving detection and quantification limits of 0.15 ㎍/kg and 0.44 ㎍/kg, respectively. Developed analysis method for Se in soil was applied to field samples in the different regions of South Korea and Se concentration ranged from 0.11 to 0.52 mg/kg. Correlation analysis between Se concentration and soil properties showed that Se concentration was significantly correlated with cation exchange capacity (CEC) and available phosphorus among other soil properties.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1233-1236
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• 2010

2,3-Dichloro-1,4-naphtoquinone 1 compound was reacted with octadecanethiol 2 in two different mole ratio. Compound 3 was obtained from the reaction of 1 and 2 in 1:2 mole/mole ratio. Compounds 7 and 8 were obtained from reaction of 1 and 2 in 1:1 mole/mole ratio and known compound 9 was synthesized as by-product in this reaction. Novel compounds 5a-e were obtained from reaction of 1 and related thiols 4a-e. Known compounds 6c and 6e were synthesized as by-product in this reaction. The structures of the compounds were characterized by elemental analysis, UV-vis, FTIR, $^1H$-NMR, $^{13}C$-NMR and Mass spectroscopies.

• Advances in Traditional Medicine
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• v.6 no.1
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• pp.65-67
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• 2006

In this study, a new extraction method was developed and two kinds of flavonoids were extracted from the mature fruit of Vaccinium uliginosum L. of China. These two kinds of flavonoids were analyzed by spectral and identified by high-performance liquid chromatography (HPLC) and UV/Vis. The extract of the fruit was total acid hydrolyzed. TLC chromatography was subsequently employed to identify the hydrolysate. Two kinds of aglycone flavonoids, quercetin and myricetin, were identified. At the same time PC chromatography was used to identify the monomer sugar in the flavonoids and it was verified as glucose. HPLC, UV/Vis, and Mass spectrum analyses revealed that the flavonoids were quercetin 3-monoglucosides and myricetin 3-monoglucosides.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2419-2421
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• 2009

A simple and efficient method has been developed for Knoevenagel condensation between aldehydes or ketones and active methylene group by stirring in methylene chloride at 60 ${^{\circ}C}$ under heterogeneous conditions using silica supported ammonium acetate. The products are obtained in excellent yields and are in a state of high purity. The structures of the products were confirmed by IR, $^1H$ NMR and mass spectral data and comparison with authentic samples available commercially.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.1011-1016
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• 2011

A series of thiadiazole derivatives were synthesized with differently substituted benzoic acids which were cyclized to give differently substituted thiazolidin-4-one. Elemental analysis, IR, $^1H$ NMR, $^{13}C$ NMR and mass spectral data confirmed the structure of the synthesized compounds. The derivatives of these moieties were evaluated for anticonvulsant activity by MES model and neurotoxicity by rotarod method. The synthesized compounds showed good potential for anticonvulsant activity besides this, the compounds also showed neurotoxic effect. It was observed that compounds with $OCH_3$ at 3, 4 position of phenyl ring [5(a-l)] showed less protection against convulsions as compared to compounds having unsubstituted phenyl ring [4(a-l)].

• Korean Journal of Food Science and Technology
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• v.19 no.5
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• pp.392-396
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• 1987

A method for isolation of some phenolic acids from Korean ginseng(Panax ginseng C.A.Meyer)was studied using silicic acid column chromatography. preparative thin layer chromatography and high performance liquid chromatography. Two phenolic compounds were isolated and identified as ferulic acid, mp $156-157^{\circ}C$ and vanillic acid. mp $154-156^{\circ}C$ by spectral data of Mass and NMR spectroscopy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1740-1746
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• 1997

In this paper, a waveguide-fed slot-coupled microstrip antenna is proposed as enhanced feeding structure of microstrip antenna and an analysis is presented. The presence of dielectric substrate between a stripand a slot is explicitly taken into account in this analysis. The evaluation of the antenna characteristics is carried out using the method of mements and the spectral domain approach in terms of the electric current distribution on the strip and the magnetic current distribution on the slot. From the results, we can conclude that the proposed structure is adequate for array antennas, due to ease of mass porduction and enhanced anteena performance.

• Natural Product Sciences
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• v.27 no.2
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• pp.122-127
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• 2021

A new steroidal saponin, (23S,24S)-spirosta-5,25(27)-diene-1𝛽,3𝛽,23,24-tetrol 1-O-((2,3-diacetyl-α-L-rhamnopyranosyl)-(1→2)-[𝛽-D-xylopyranosyl-(1→3)]-α-L-arabinopyranoside)-24-O-𝛽-D-glucopyranoside (humilisoside) together with the known 𝛽-sitosterol 3-O-glucopyranoside, adenosine, dioscin, and methylprotodioscin were isolated from the leaves of Dracaena humilis. Their structures were elucidated by spectral techniques including mass spectrometry (ESIMS, HRESIMS, tandem MS-MS), 1D NMR (¹H, ¹³C NMR), 2D NMR (HSQC, ¹H-¹H COSY, HMBC, NOESY), chemical method as well as by comparison with spectroscopic data reported in the literature. The chemotaxonomic significance of the isolation of these compounds is discussed. This is the first report on the phytochemical investigation of D. humilis.