• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.664-672
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• 2011

A series of hydrophilic chromophores was synthesized through introduction of dendritic sulfonate anions using click chemistry. A dendron structure bearing several sulfonate groups enhances hydrophilicity of attached chromophores. A click triazole formation connects chromophores with hydrophilic groups. A neutral trichloroethyl sulfonate has versatile features such as easy introduction, chemical endurance for isolation or storage, and convenient transformation to a hydrophilic anion. Zinc and OH mediated cleavage of trichloroethyl group from the neutral sulfonate undergoes to generate a water-soluble sulfonate anion. The solubility was examined with different counter cations and in different pH media and thus increased with the number of attached sulfonate ion. Two hydrophilic chromophores of stilbene-derived and azobenzene-derived dipolar structures exhibit clear negative and positive solvatochromism in protic solvents, respectively.

• YAKHAK HOEJI
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• v.36 no.3
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• pp.250-254
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• 1992

Benzo[C]phenanthidine alkaloids were found to exhibit considerably strong antileukemic activies. These alkaloids have been shown to be biosynthesized from the corresponding alkaloids throung an oxidative $C_6-N$ bond cleavage followed by recyclization between $C_6\;and\;C_{13}$ position of the protoberberine. Recently we have achieved the biomimetic transformation of protoberberine alkaloid, berberine into benzo[C]phenanthridine alkaloid, chelerythrine.

• Journal of Environmental Health Sciences
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• v.28 no.4
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• pp.1-5
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• 2002

Drosophila Kc cells are ecdysone-responsive : hormone treatment leads rapidly to increased synthesis of several ecdysone-inducible polypeptides (EIPs) and to commitment to eventual proloferative arrest. Later the treated cells undergo morphological transformation, cease to proliferate and to grow. These responses have proven useful as models for studying ecdysone action and environmental endocrine disrupting actions. In this study, we used 20-HE to check out the Kc cells properties to the ecdysone and this properties will be applied to the environmental chemicals to find out the endocrine disrupting action in ecosystem. The cell counts of cultures harvested after 3 days' growth in the presence of 20-hydroxyecdysone. In Kc cell cultures, there were statistically significant different from control cells at 20HE 10/sup 7/-10/sup 5/. The morphological effects of all the hormones were similar, differing only in the dose level at which they were initiated.

• Textile Coloration and Finishing
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• v.26 no.1
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• pp.7-12
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• 2014

Nowdays, fluorescent rhodamine chemosensors have attracted a worldwide interest due to its ability to selectively detect heavy and transition metal cations. Due to the importance in environmental and biological toxic effects, the developments of fluorescent chemosensors have been received considerable attention in recent. Especially, a rhodamine-based chemosensor probes have been proved to be useful by exhibiting the efficient "off-on" fluorescence switching toward selected metal cations. This fluorophore can undergo the transformation from non-fluorescent and colorless spirolactam derivative to fluorescent ring-open form. In this study, a new fluorescent chemosensor was synthesized using rhodamine B through two-step procedures, and its selectivity and related optical property were characterized. Selectivity and sensitivity was found toward $Cu^{2+}$ guest molecules and then related optical properties of rhodamine B based fluorescent chemosensor compound were characterized using discussed. In addition, computational calculation was used to determine the HOMO/LUMO values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1346-1353
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• 2007

In this paper, the methods are presented for the calculation of general coupling coefficient matrixes used in the band pass filter design. They are calculated from transmission coefficient($S_{21}$) and reflection coefficient($S_{11}$) with desired characteristics derived from the poles of filter function and return loss(RL). The calculated matrixes from this method are transformed to the folded canonical filter structure using similarity transformation which lends us the practical filter design. Based on the resulting matrix, the folded canonical filter has been designed.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.235-241
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• 1996

Self-Propagating high temperature synthesis(SHS) technique was used to synthesize the spinel phase of MgAl2O from MgO and Al powder. Processing factors such as mixing time preheating temperature and ignition catalyst were varied to determine the optimum condition to form MgAl2O4 phase. The reaction products were heat treated at the temperature range of 120$0^{\circ}C$ and 150$0^{\circ}C$. to observe phase transformation of unreacted materials. Processing factors such as 48 hrs-mixing 80$0^{\circ}C$-preheating and 20wt% KNO3-ignition catalyst were effective of the formation of MgAl2O spinel. An activation energy 49.7kcal/mol. was calculated to form a MaAl2O4 spinel from unreacted materials.

• Journal of the Korean Ceramic Society
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• v.37 no.12
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• pp.1131-1134
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• 2000

Hydroxyapatite (HA) ceramic was prepared using tuna bone powders and was characterized on properties of sintered samples. The aim was to prepare dense and bulk HA sintered suitable for clinical applications. Thermal analysis, X-ray diffraction analysis, microscopic observation, and mechanical evaluation were applied to characterize sintered HA to find optimum processing condition. The major phase of sintered HA was observed up to 1300$\^{C}$ and $\beta$-TCP was observed as temperature increased. The density of sintered HA was increased up to 1350$\^{C}$ and decreased with further increasing temperature. The flexural strength of sintered HA at 1350$\^{C}$ showed 58 MPa as the highest value in this work. The results suggest that the crystal phase and transformation characteristics of HA prepared from tuna bone are the same as the behavior of HA powders made by chemical synthesis.

• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.302-306
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• 1999

The 1,3-dipolar cycloaddition reaction of the quinoxaline 4-oxide 10 with 2-chloroacrylonitrile gave the 2,3-dihydro-lH-1,2-diazepino[3,4-blquinoxalines lla, b, respectively, which were converted into the 2,3,4,6-tetrahydro-lH-l,2-diazepino[3,4-b]quinoxaline 12. The reaction of compound lla with selenium dioxide in acetic acid/water resulted in ring transformation to give the 1,4-dihydro-4-oxopyridazino[3,4-blquinoxaline 13.

• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.463-472
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• 2006

The preparation of enatiomerically enriched homoallylic alcohols through asymmetric addition of chiral allylic transfer reagents and allylating reagents with chiral catalysts to the carbonyl functionalities represents an important chemical transformation. Excellent progress has been made over past decade in the development and application of catalytic asymmetric allylic transfer reactions. In this account, our efforts for the various intermolecular allylic transfer reactions such as allylation, propargylation, allenylation, and dienylation utilizing accelerating strategy and sequential allylic transfer reactions to achieve multiple stereoselection mainly using transition metal catalysts are described.

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.19-49
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• 1987

Recent development of recombinant DNA techniques such as gene cloning and DNA sequencing has led to understanding of genetic information coded on plant genes and their application to crop improvements. Nuclear genes so far isolated and characterized at the molecular level from various plants are those involved mainly in photosynthesis, nitrogen fixation, seed development and defensive responses to environmental stresses. Most of plant genes contain intervening sequences (introns) flanked with GT and AG, as it typical of animal genes. The 5' flanking regions of plant gene revealed the presence of promoter elements such as TATAAA and CCAAT, which have been identified at animal genes to be involved in transcrip- tion initiation. The 3' untranslated regions include a sequence similar to AATAAA whcih functions as a polyadenylation signal in other eukaryotic genes. Furthermore, enhancer-type sequences were found at the 5' flanking regions of various plant genes. This indicates that the structure of plant genes is very similar to animal genes and mechanisms governing the synthesis and processing of mRNAs may be identical in higher eukaryotes. However, genes expression studies involving transformation revealed their differ ences within plants and between plant and animal systems.