• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.771-776
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• 1993

Aqueous extraction of sea tangle at the temperature range of 60~10$0^{\circ}C$ was studied for temperature effects on soluble solids and protein yields, amino nitrogen, turbidity and viscosity of extracts. The solids and protein yield were increased as the temperature increased and most of solids and protein were extracted during 1 hour. The supernatant ratio after centrifugation showed significantly low for the extraction at 6$0^{\circ}C$. More temperature effects were found on turbidity and viscosity than yields. A significantly higher total amino nitrogen contents was obtained from higher temperature at initial stage of extraction and then the differences of them became to be narrow as the extraction prolonged further. The low values of 24.1% solids and 13.5% protein yields after 2 hours of extraction at 10$0^{\circ}C$ indicated that most of solids in sea tangle are insouble.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.53-55
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• 1986

The $trans{\rightarrow}cis$ photoisomerization and fluorescence of trans-1,2-bispyrazylethylene were investigated in various conditions. The quantum yields of the $trans{\rightarrow}cis$ photoisomerization and the fluorescence intensity of trans-1,2-bispyrazylethylene decrease on going from neutral to acidic or basic solutions. The quantum yields of photoisomerization, however, are little affected by changing the concentration of salt while the fluorescence intensity increases as the concentration of salt increases. pH and salt effects on the energy levels of $^1(n,\;{\pi}^*)\;and\;^1({\pi},\; {\pi}^*)$ states lead to opposing changes in photoisomerization and fluorescence quantum yields. The heavy atom effect on the fluorescence of 1,2-bispyrazylethylene was also investigated.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.80-84
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• 1989

Two properties of sodium naphthalenide (2), i.e. a strong base and a good electron donor were utilized for one pot synthesis: 2-alkylthiobenzimidazoles were synthesized in excellent yields from the reactions of benzimidazoline-2-thione (1) with an equimolar amount of alkyl halides in the presence of 2. Continuous addition of a different alkyl halide without the isolation of 2-alkylthiobenzimidazoles afforded 1-alkyl-2-alkylthiobenzimidazoles having different alkyl groups at N and S atoms in excellent yields. Further addition of 2 to 1-alkyl-2-alkylthiobenzimidazoles gave excellent yields of 1-alkylbenzimidazoline-2-thiones. When 2 in THF was added to a suspension of 1-alkyl-2-alkylthiobenzimidazoles in THF, a bond cleavage between N and C of alkyl group as well as S and C of alkyl group occurred. This is in contrast to the observation in which only cleavage between S and C of alkyl group takes place in the homogeneous solution.

• Journal of agriculture & life science
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• v.43 no.4
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• pp.1-8
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• 2009

The physically based model KINEROS2 was applied to forest road segments for simulating hydrology and sediment production. Data on rainfall amounts, runoff volume, and sediment yields were collected at two small plots in the Yangpyong experimental watershed. The KlNEROS2 model can be parameterized to match the volume of surface flow and sediment yields during seven storm events. Model predictions of hydrology were in good agreement with the observed data at two plots in the year 1997 and 1998. A comparison between the observed and predicted sediment yields indicated that the model provided reasonable estimates, although the model tended to under-estimate for some storm events. The overall result shows that the KINEROS2 model properly represents the hydrology and sediment transport processes in the forest road segments.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1080-1083
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• 1998

An efficient method for construction of 2-arylfiirans has been developed by ceric(IV) ammonium nitratemediated oxidative cycloaddition of cyclic and acyclic 1,3-dicarbonyl compounds to several alkynes. Reactions of 1,3-cyclohexanedione, 1,3-cyclopentanedione, and 2,4-pentanedione with several alkynes furnish 2-arylfurans in 26-75% yields. Extension of this technology to more complex 4-hydroxy-2-quinolone and 3-hydroxy-lH-phenalen-l-one with phenylacetylene also affords furoquinolinone and ftirophenalenone derivative in moderate yields. Reaction of 4-hydroxycoumarins with phenylacetylene give linear and angular furocoumarin derivatives as a mixture of regioisomer in good yields. The mechanistic pathway for the formation of 2-arylfurans has been also described.

• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1337-1340
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• 2001

The bulk photopolymerization of methyl methacrylate (MMA) with para-substituted phenylsilanes such as F-C6H4SiH3 (1), H3C-C6H4SiH3 (2), and H3CO-C6H4SiH3 (3) was performed to produce poly(MMA)s containing the respective silyl moiety as an end group. For all the hydrosilanes, the polymerization yields and the polymer molecular weights decreased, whereas the TGA residue yields and the relative intensities of Si-H IR stretching bands increased as the relative silane concentration over MMA increased. The polymerization yields and polymer molecular weights of MMA with 1-3 increased in the order of 3 < 1 < 2. These hydrosilanes influence significantly upon the photopolymerization of MMA as both chain-initiation and chain-transfer agents.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.532-535
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• 1996

The bulk photopolymerization of methacrylic acid (MA) with secondary silanes such as PhMeSiH2 and Ph2SiH2 gave poly(MA)s possessing the secondary silyl moiety presumably as an end group. It was found that while the polymerization yields and intrinsic viscosities decreased, the TGA residue yields and the relative intensities of SiH IR stretching bands increased with increasing mole ratio of the secondary silane over MA. The sterically less bulky silane PhMeSiH2 produced poly(MA)s with somewhat higher molecular weights and with similar TGA residue yields compared with the sterically bulkier silane Ph2SiH2. The secondary silanes seem to significantly influence on the photopolymerization of MA as both chain initiation and chain transfer agents.

• Bulletin of the Korean Chemical Society
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• v.7 no.3
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• pp.235-237
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• 1986

Reaction of $(E)-{\beta}-chloro-{\gamma}$-hydroxyvinylmercurials, prepared by mercuration of propargyl alcohol and 2-methyl-3-butyne-2-ol, with olefins in the presence of a catalytic amount of $Li_2PdCl_4$ and 2 equiv of cupric chloride in methanol at $50^{\circ}C$ gave the corresponding (E,E)-2,4-dienols in moderate yields. However, addition of 1 equiv of inorganic bases such as magnesium oxide to the reaction mixture brings a rapid and clean vinylation and gave high yields of the dienols at room temperature. In the case of hindered (E)-2-chloro-3-chloromercuri-2-buten-1,4-diol prepared from 2-butyne-1,4-diol, reaction with olefins gave the dienols only in low yields even in the presence of 2 equiv of magnesium oxide.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.246-250
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• 1987

The reaction of aryl iodides or bromides with olefins in the presence of 1 mol % of $PdCl_2(PPh_3)_2$ and 3 equiv. of $n-Bu_3N\; at\; 100^{\circ}C$ in carbon monoxide atmosphere gave the corresponding aryl vinyl ketones in good yields with small amount of vinylated 1-aryl olefins. But, when the reaction was proceeded under the 10 atm of carbon monoxide, aryl vinyl ${\alpha}$-diketones and aryl vinyl ketones were obtained in moderate to good yields. The reaction was tolerant of a wide variety of functional groups on either the aryl halides or olefin compounds. Reactivity of aryl halide decrease in the order; aryl iodide > aryl bromide ${\gg}$aryl chloride. In general, the reaction proceeded well and gave good yields of aryl vinyl ketones and aryl vinyl ${\alpha}$-diketones when reactants are substituted with electron withdrawing groups.

• Advances in nano research
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• v.14 no.3
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• pp.225-234
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• 2023

In this study, we aim to use big data resources and statistical analysis to obtain a reliable instruction to reach high-quality and high yield agricultural yields. In this regard, soil type data, raining and temperature data as well as wheat production in each year are collected for a specific region. Using statistical methodology, the acquired data was cleaned to remove incomplete and defective data. Afterwards, using several classification methods in machine learning we tried to distinguish between different factors and their influence on the final crop yields. Comparing the proposed models' prediction using statistical quantities correlation factor and mean squared error between predicted values of the crop yield and actual values the efficacy of machine learning methods is discussed. The results of the analysis show high accuracy of machine learning methods in the prediction of the crop yields. Moreover, it is indicated that the random forest (RF) classification approach provides best results among other classification methods utilized in this study.