• Journal of the Korean Magnetic Resonance Society
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• v.13 no.1
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• pp.35-55
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• 2009

The two correlation times previously obtained in our coupled $^{13}C$ relaxation measurement for the methyl group in 2,6-dichlorotoluene may be used as a criterion for evaluating the reorientation dynamics of an internal rotor. We numerically tested an extended diffusion model and the Smoluchowski diffusion equation to see how the rotational inertial effect and jump character contribute to the internal correlation time ratio of the internal rotor. We also analytically solved the general jump model with three different rate constants in a sixfold symmetric potential barrier. By assuming that the internal rotation of the methyl group in 2,6-dichlorotoluene can be described in terms of jumps among sixfold harmonic potential wells, we can conclude that the jump model satisfactorily reproduce the experimental data and the rate for sixfold jump is at least 1.53 times as great as that of a threefold jump.

• Fibers and Polymers
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• v.2 no.1
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• pp.131-134
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• 2001

Living cationic polymerization behaviors of isobutyl vinyl ehters (IBVE), initiated by iodomethyl methyl ether (IMME)/zinc iodide ($Znl_2$) have been investigated. The polymerization was carried out at 0, -15, and $-30^{\circ}C$ in toluene. It was found that the rate of polymerization increased as the IMME concentration increased and decreased as temperature decreased. 100% conversion was always achieved without exception. Furthermore, the number-average molecular weight ($M_{n}$) of polymers increased in direct proportion to monomer conversion. The molecular weights of polymers were in good agreement with the theoretical values, calculated on the basis that one polymer chain was formed by one IMME molecule and the values of polydispersity index are always less than 1.2, revealing the living nature. The living nature was also confirmed by synthesis of poly(IBVE-b-TBVE) by subsequent monomer addition of t-butyl vinyl ether (TBVE).

• Elastomers and Composites
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• v.28 no.3
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• pp.191-197
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• 1993

The graft copolymerization of methyl methacrylate(MMA) onto natural rubber latex(NRL) initiated by t-butyl hydroperoxide(t-BHPO) was investigated in aquous medium. The grafting percentage, grafting efficiency and total conversion were observed in various reaction conditions such as monomer, initiator and emulsifier concentration, reaction temperature, reaction time and agitation speed. The optimum conditions for the graft copolymerization onto natural rubber latex were as follows ; At given monomer concentration of $3{\times}10^{-2}mole/l$, the maximum grafting percentage was appeared in the case of grading in initiator concentration of $4{\times}10^{-2}mo1e/l$ and emulsifier concentration of 0.2wt.% at $40^{\circ}C$ for 5hrs.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.249-255
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• 2009

In order to calculate the processing and reduction factor between fresh and dry Welsh onion which was widely used as a dried agricultural ingredient of food in Korea. 7 pesticides such as pyridalyl, kresoxim-methyl, spinosad, flufenoxuron, difenoconazole, metconazole, and tebufenozide were tested. After 2 sites field trial conducted and measured water contents by drying at $60^{\circ}C$ and analyzed the pesticide residue. Water contents of fresh and dried Welsh onion are 89.2 and 10.2% respectively. Averages of processing factor showed 7.24 of pyridalyl, 2.85 of kresoxim-methyl, 7.43 of spinosad, 3.17 of flufenoxuron, 4.38 of difenoconazole, 2.40 of metconazole and 8.13 of tebufenozide into 2 field samples. Averages of Reduction factor showed 0.87 of pyridalyl, 0.35 of kresoxim-methyl, 0.88 of spinosad, 0.38 of flufenoxuron, 0.52 of difenoconazole, 0.29 of metconazole and 0.98 of tebufenozide. Residual amounts of pesticides in/on fresh Welsh onion reduced during drying process.

• Clean Technology
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• v.20 no.2
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• pp.146-153
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• 2014

In this study, the effect of alkanolamine additives, 2-amino-2-methyl-1-propanol (AMP) and 2-amino-2-methyl-1,3-propanediol (AMPD) on $CO_2$ absorption rate of $K_2CO_3$ solution and the formation of $KHCO_3$ crystals was investigated. The normalized $CO_2$ flux and the equilibrium $CO_2$ partial pressure were measured for 5 wt% additives and 30 wt% $K_2CO_3$ mixtures using a wetted-wall column unit at $40^{\circ}C$ and $60^{\circ}C$. Both additives showed the increased $CO_2$ absorption rate and lowered the equilibrium $CO_2$ partial pressure acting as promoters. Besides, AMPD which has two hydroxyl groups enhanced the formation of $KHCO_3$ solid product separated from the $CO_2$-rich solution from the results of batch cooling crystallization experiments.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.139-144
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• 2014

Activated carbon fiber (ACF) was modified with MnS nanoparticles to prepare MnS-ACF, and it was employed for preparation of MnS-$ACF/TiO_2$ composites with titanium (IV) n-butoxide (TNB). The properties of MnS-$ACF/TiO_2$ composites were characterized by XRD, SEM, and EDX. EDX results showed the presence of C, O, and Ti as major elements and traces of the metal elements Mn and S. The photocatlytic activity was evaluated by degradation of methyl blue (MB) and methyl orange (MO) dye. The results demonstrated that as-prepared samples could effectively photodegrade MB and MO under UV irradiation. Subsequently, the decomposition of MB solution showed the combined effects of adsorptions by ACF and enhanced photocatalytic effect by $TiO_2$. Finally, the photocatalytic effect increased due to photo-induced-electron absorption effect by ACF and electron trap effect by comodified MnS nanoparticles.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.50-55
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• 2000

Soluble methyl-hesperidin (MH) powder was prepared from crude MH, and was investigated on the stabilization to sunlight of natural coloring matter. Soluble MH powder was added to riboflavin, bixin, and paprika oleoresin solutions at concentration of 0.1 or 0.2%(w/w), and the absorbance of respective solutions was analyzed by spectrophotometer after exposing to sunlight for $10{\sim}24$ hr. While coloring matter solutions without MH was faded completely with lapse of time, addition of MH retarded to fade natural coloring matters. According as amount of MH added increased, MH showed more excellent stabilizing effect on the coloring matters. Especially, vitamin C with soluble MH showed remarkable synergistic effect in paprika oleoresin solution during the exposure to sunlight for 8 hr. Consequently, it was found that MH plays a role as excellent stabilizer of natural coloring matters to ultraviolet of sunlight.

• Bulletin of the Korean Chemical Society
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• v.7 no.5
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• pp.338-341
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• 1986

Hydrocarbon solution of $Ir(PPh_3)_2(CO)OClO_3$ reacts with $Ph_2PC_6H_4$-o-CHO and 3-methyl-2-aminopyridinyl aldimine to yield ${\bar{Ir(Ph_2PC_6H_4-o-CO)}}\;(PPh_3)_2(CO)(H)ClO_4$(1) and ${\bar{Ir(NC_6H_6NC}}C_6H_5)(PPh_3)_2(CO)(H)ClO_4$(2), respectively. The compound $Ir(PPh_3)_2N_2Cl$ also reacts with $Ph_2PC_6H_4$-o-CHO and 3-methyl-2-aminopyridinyl aldimine to give ${\bar{Ir(Ph_2PC_6H_4-o-C}}O)(PPh_3)_2(H)Cl(3)$ and $Ir(NC_6H_5NCC_6H_5(PPh_3)_2(H)Cl(4)$, respectively. Compounds 1, 2, 3, and 4 were characterized by infrared, $^1H$ NMR, $^{31}p$ NMR, UV spectra, and conductivity measurements.

• Journal of the Korean Chemical Society
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• v.60 no.2
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• pp.149-153
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• 2016

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.25-32
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• 1986

This experiment was conducted to evaluate effect of various hormones on callus induction, and on plantlet formation on various media, and to detect of Londax [Methyl 2-[[[[[(4,6-dimethoxy pyrimidin-2-yl) amino] carbonyl] amono] sulfonyl) methyl] benzoate] and Basta[Ammonium-(3-amino-3-carboxy-propyl)-methyl phosphinate] on callus growth and reaction of succinate dehydrogenase in callus against TTC, using various species such as Eleocharis kuroguwai, Cyperus serotinus, Oryza sativa (samgangbyeo) and Echinochloa crusgalli P. Beauv. var. caudata Kitagawa. The optimal levels of 2,4-D in MS medium seems to be different among species tested, 2.0 ppm for rice and E. crusgalli, 1.0 ppm for Eleocharis kuroguwai, and 4.0 ppm for C. serotinus derived callus from shoot-tip. In case of combination of 2,4-D with BA, 1.0 plus 0.3 ppm appeared the most appropriate level to induce callus from rice and E. kuroguwai, and I.0 plus 0.1 ppm for C. serotinus and E. crusgalli. When 2,4-D treated with TIBA, 1.0 plus 0.5 ppm appeared the most appropriate rates to induce callus derived from seeds of rice, E. crusgalli, seeds of C. serotinus and E. kuroguwai, 1.0 plus 0.3 ppm for shoot-tip of C. serotinus. Positive reaction of succinate dehydrogenase against TTC was observed regardless of calli and herbicides tested, indicating that they all are alive, and these herbicides were not able to kill the calli tested within the short period of time 20 hrs treatment. Regardless of plant species used, the rate of plantlet formation from callus was very low. However, some plantlet formed from E. crusgalli at 0.8 ppm of 2,4-D plus 8.0 ppm of kinetin, and from E. kuroguwai at 1.6 ppm of 2,4-D plus 16.0 ppm of kinetin, showing effectiveness of 2,4-D with kinetin mixture treatment. No callus was induced from C. serotinus treated with Basta from $10^{-6}M$ to $10^{-3}M$. In general, rice was the least susceptible to Basta among plant species tested, followed by E. crusgalli, and E. kuroguwai. In Londax treatment, rice showed the least inhibition rate in callus growth. Callus was induced from rice even at $10^{-3}M$ of Londax. However, $10^{-3}M$ of Londax completely inhibited callus induction from the test species. Rice showed most tolerant to both herbicides, indicating the existence of different responses among plant species.