• 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.

• YAKHAK HOEJI
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• v.42 no.3
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• pp.233-237
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• 1998

Activity-guided fractionation and repeated column chromatography afforded two cytotoxic compounds R-3 and R-4 from the root of Rumex japonicus HOUTT. Compou nds were identified as musizin and emodin, respectively, by the physicochemical and spectral data. Besides R-3 and R-4, two compounds R-1 and R-2, chrysophanol and physcion, respectively, were also isolated. The compound R-3 and R-4 exhibited cytotoxicity against cultured human tumor cell lines, A-549, SK-OV-3, SK-MEL-2, XF498 and HCT15 with $ED_{50}$ values ranging from 2.68 to $10.06{\mu}g/ml$.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.421-429
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• 1993

Dissolution reactions of chemical grade zinc sulfide and natural sphalerite were studied in ferric chloride solution as an oxidant. To enhance the leaching reaction, ultrasonic technique was employed in this investigation. For the reaction with pure zinc sulfide, chemical reaction was the rate limiting step in the range of low conversion irrespective of applying ultrasonic wave. And the diffusion through liquid film instead of diffusion through product layer of free sulfur was the rate determining step because ultrasonic vibration removes the product from reaction zone. In the case of sphalerite with the ultrasonic vibrator, it was found that inert mineral layer diffusion was the rate determining step, in which the elemental sulfurs formed were removed by the ultrasonic action. Experimental results showed that the ultrasonic technique proved to be the methods which can significants improve the leaching performance.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1665-1669
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• 2014

Four multialkoxy-functionalized siloxane base-polymers (BP-1~4) were synthesized through either hydrosilylation or condensation reactions in order to prepare multi-networked siloxane polymers having appropriate physical properties for protective coating in fabrications of electronics. Formulations of 4 base-polymers gave coating materials A and B. Product A showed well-controlled flowing and leveling properties, and product A-2 was successfully applied to protective insulating coating for junction areas of connectors and chips in PDP controller. Tack free time, extrusion rate, dielectric breakdown voltage, hardness, thermal stability, water resistance and flame resistance of products A and B were examined.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3782-3786
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• 2013

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and that accounts for 85% of lung cancer patients. Although several EGFR-targeted drugs have been developed in the treatment of NSCLC, the clinical efficacy of EGFR-targeted drugs in NSCLC is limited by the occurrence of drug resistance. In this regard, Hsp90 represents great promise as a therapeutic target of cancer due to its potential to simultaneously disable multiple signaling pathways. In this study, we discovered that a natural product, flavokawain B disrupted Hsp90 chaperoning function and impaired the growth of gefitinib-resistant non-small cell lung cancer (H1975). The result suggested that flavokawain B could serve as a potential lead compound to overcome the drug resistance in cancer chemotherapy.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.721-724
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• 2014

We have explored the potential energy surface for the dissociation of the pyridazine molecular ion using G3 model calculations. The pathways have been obtained for the formation of five possible $C_4H_4^{+{\bullet}}$ isomers by the loss of $N_2$ and the consecutive $H^{\bullet}$ loss. It is predicted that the methylenecyclopropene radical cation is the predominant product in the loss of $N_2$, which is formed via the allenylcarbene radical cation, and $CH_2=C-C{\equiv}CH^+$ is the predominant product in the consecutive $H^{\bullet}$ loss.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.146-151
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• 1992

A two-compartment four-cell model is developed for the adiabatic autoclave slim type reactor for free radical polymerization of low density polyethylene(LDPE). The mass and energy balances give rise to a set of ordinary differential equations, and by analyzing the system it is possible to predict properly not only the reactor performance but also the properties of polymer product. The steady state multiplicity is found to exist and examined by constructing the bifurcation diagram. The effects of various operation parameters on the reactor performance and polymer properties are investigated systematically to show that the temperature distribution plays the central role for the properties of polymer product. Therefore, it is essential to establish a good control strategy for the temperature in each compartment. In this study it is shown that the reactor system can be adoptively controlled by pole-placement algorithm with conventional PID controller. To accomplish a satisfactory control, the estimator and controller are initialized during the period of start-up.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.86-91
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• 2005

A metal product obtained from an electrolytic reduction process, possesses less volume and radioactivity than those of the unprocessed spent oxide fuels. The chemical composition of the metal product varies according to the process condition. In this work, a basic study was performed to evaluate the chemical forms of the spent oxide fuel components in an electrolytic reduction process with the operation conditions. One of the most important operation conditions is the cell potential applied for the reduction cell. It is expected that $PU_{2}O_3$ is difficult to reduce even though the cell potential is negative enough to reduce the lithium oxide when the activity of $Li_{2}O$ exceeds 0.003. The reduction of actinide oxides via the reduction of $Li_{2}O$ is assumed to have a greater reduction yield than a direct reduction of the actinide oxides.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3274-3278
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• 2013

$CF_2Cl{\cdots}Cl$, an elusive photo-isomer of $CF_2Cl_2$, has been observed in matrix IR spectra from the precursors exposed to radiation from laser ablation of transition-metals. Other plausible products, $CFCl_2{\cdots}F$ and $FClC{\cdots}F-Cl$ are not detected due to their considerably higher energies. Parallel to its previously reported analogues, the C-X bonds are considerably stronger than those of the reactant, and particularly the Cl atom that is weakly bound to the residual Cl atom forms an unusually strong carbon-halogen bond. NBO analysis reveals that the C-Cl bond is a true double bond, and the weak $Cl{\cdots}Cl$ bond is largely ionic, $F_2C=Cl^{\delta+}{\cdots}Cl^{\delta-}$. IRC computation reproduces smooth inter-conversion between the reactant and product, and the transition state is energetically close to the product, consistent with its prompt disappearance in the early stage of photolysis.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1515-1518
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• 2007

A preparative method of Me2SCuX (X = Cl, Br) via one-pot reaction was developed from common chemicals such as benzyl halide, DMSO, and Cu(0). In the reaction mixture small molecules such as methyl halide and dimethyl sulfide etc. were efficiently generated in situ, resulting in the formation of Me2SCuX. Oxidation of Cu(0) in reacting with both benzyl halide (starting material) and methyl halide (in situ generated product) to Cu(I) followed by complexing with dimethyl sulfide (in situ generated product) could explain the formation of Me2SCuX. In particular we found out that heterogeneous reaction of Me2SCuX and arenediazonium tetrafluoroborate in acetonitrile was so effective to afford corresponding bromoaromatics under mild conditions.