• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.382-387
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• 2018

In this study, the reaction characteristics of combined steam and carbon dioxide reforming of methane (CSCRM) reaction using Pd-Ni-YSZ catalyst were investigated according to types of catalysts and gas compositions. Catalysts were prepared in the form of powder and porous disk. The injected gases were supplied at different ratios of $CH_4/CO_2/H_2O$. As a result, the conversion of $CH_4$ and $CO_2$ was improved as a result of using the porous disc type catalyst as compared with that of the powder type catalyst. When the $CH_4/CO_2/H_2O$ ratio of the feed gas was 1 : 0.5 : 0.5, the $H_2/CO$ ratio was adjusted close to 2. However, after 6 hours of the reaction, $CH_4$ conversion was partially reduced by the carbon deposition and the pressure drop increased from 0.1 to 0.8. This issue was then solved by optimizing the water content. As a result, it was confirmed that the durability was secured by preventing the carbon deposition when the gas was supplied at a $CH_4/CO_2/H_2O$ ratio of 1 : 0.5 : 1, and the conversion rate was maintained at a relatively high level.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.139-145
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• 1980

High spin iron(II) complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam), a macrocyclic ligand, and 1,5,8,12-tetraazadodecane (3,2,3-tet), a noncyclic ligand, have been prepared. The reaction of low spin $[Fe(cyclam)(CH_3CN)_2](ClO_4)_2$ with chloride ion in methanol produces high-spin $[Fe(cyclam)Cl]ClO_4$. Although $[Fe(cyclam)(CH_3CN)_2](ClO_4)_2$ is low spin, $[Fe(3,2,3-tet)(CH_3CN)_2](ClO_4)_2$ isolated in the present study is high spin. This difference is explained in terms of the smaller constrictive effect exerted by the noncyclic ligand than the cyclic ligand. The isolation of $[Fe(cyclam)Cl]ClO_4$ provides evidences against the current view that the presence of either unsaturation or substituents on the macrocyclic ligands is necessary for the successful preparation of high spin five-coordinate iron (II) complexes. Reactions of $[Fe(cyclam)Cl]ClO_4\;and\;[Fe(3,2,3-tet)(CH_3CN)_2](ClO_4)_2$ with carbon monoxide yield low spin six-coordinate $[Fe(cyclam)Cl(CO)]ClO_4\;and\;[Fe(3.2,3-tet)(CH_3CN)(CO)](ClO_4)_2$, respectively.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.240-248
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• 1991

The regioselectivity in the nitrosation of seven N-methyl-N'-substituted phenylureas ($CH_3NHCONHC_6H_4-G$; G = H, p-CH$_3$, m-CH$_3$, m-CH$_3$O, p-F, m-F, m-Br) was examined using NaNO$_2$ and 4 different acids (diluted HCl, HCOOH, CH$_3$COOH, CF$_3$COOH). In all cases, the two regioisomeric products, N-nitroso-N-methyl-N'-substituted phenylureas (A) and N'-nitroso-N-methyl-N'-substituted phenylureas (B) were observed to be formed as major products and product ratios were determined by the integration of their methyl peaks in $^1$H-NMR. Electron donating substitutent(G) on phenyl of the ureas generally led to increase the ratio of B to A. The data have revealed that the relative sensitivity of the nitrosonium species (HONO, HCOONO, CH$_3$COONO, CF$_3$COONO) toward the change of electron density on nitrogen with phenyl substitutents are 1.00 : 0.93 : 0.78 : > ∼ 0.7.

• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.46-52
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• 2006

studies of olefin oxidation using Al(III)-porphyrin complexes as catalyst are investigated in CH2Cl2, in which NaClO is used as terminal oxidant. Porphyrins are TPP(5,10,15,20-Tetraphenylporphyrin) and (p-X)TPP(X=CH3O, CH3, F, Cl). Olefins are styrene and (p-X)styrene (X=CH3O, CH3, Cl, Br). The values of Km and Vmax are calculated from the Michaelis-Menten equation. According to the substituents of substrate and catalyst, kinetic parameters will be measured. Investigating the correlation between the Michaelis-Menten rate parameters and the substituent constants, we were able to analyze the influence on the changes of catalytic activity or the rate determining step during the process of the formation and the dissociation of the M-oxo-olefin.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.456-460
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• 1999

Rates of 1-adamantyl fluoroformate with substituted pyridines ($3-CH_3,\;4-CH_3,\;H,\;3-Cl,\;3,4-(CH_3)_2,\;3,5-(CH_3)_2$) in methanol have been measured by conductometric method at various temperatures and concentrations. The activation parameters (${\Delta}H^{\neq},\;{\Delta}S^{\neq}$) and Hammett reaction constant (${\rho}$) or Bronsted coefficient (${\beta}$) were evaluated from rate constants. The activation entropies are large and negative, and the activation enthalpies are small and positive. The Hammett reaction constant (${\rho}$) and Bronsted coefficient (${\beta}$) values were -4.15 and 0.63, respectively. From the above results, it may be concluded that this reaction proceeds to a concerted displacement mechanism in methanol.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.553-557
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• 2005

The formation of striped phases of unsymmetric hexyl octadecyl disulfide ($CH_3(CH_2)_5SS(CH_2)_{17}CH_3$, HOD) and 1-hydroxyundecyl octadecyl disulfide ($CH_3(CH_2)_{17}SS(CH_2)_{11}$OH, HUOD) on Au(111) and graphite has been investigated by scanning tunneling microscopy (STM) to understand the self-assembly processes of dialkyl disulfides. STM imaging clearly shows the formation of striped phases having corrugation periodicities that are nearly consistent with the molecular length of alkanethiolate moieties formed after the S-S bond cleavage of dialkyl disulfide on a gold surface. On the other hand, self-assembled monolayers (SAMs) of dialkyl disulfides on a graphite surface displayed long-range, well-ordered monolayers with one striped pattern that shows periodicity as a function of molecular length via nondissociative adsorption. From a nonoscopic viewpoint, we have clearly demonstrated that dialkyl disulfide SAMs on gold form via S-S bond cleavage of disulfide.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1328-1333
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• 2004

The Flame length of $CH_4$ with the Oxidizer of air and $O_2$ has been measured respectively for the nozzle diameter of 1.6mm, 2.7mm, 4.4mm and 7.7mm. In all $CH_4$ flame on oxidizer of air and $O_2$. the flame length was independent of the initial jet diameter, dependent only on the flowrate in laminar flame regime, and in turbulent flame dependent on the initial jet diameter. Using correlation equation of Delichatsios, the flame length has been expected exactly for $CH_4/air$ flame, but has been underestimated for $CH_4/O_2$ flame. This paper has proposed correlation equation of $CH_4/O_2$ flame.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.3
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• pp.214-220
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• 2007

The effects of soil percolation rate on $CH_4$ and $N_2O$ emissions were investigated from paddy fields with different drainage systems. Subsurface tile drainage plot of soil percolation rate $11.9mm\;d^{-1}$ and non-subsurface drainage plots of soil percolation rate $7.4mm\;d^{-1}$ and $6.9mm\;d^{-1}$ were designed. The effects of rice straw application were measured at each drainage plots. The subsurface tile drainage plot of soil percolation rate $11.9mm\;d^{-1}$ showed the lower emission amount both of $CH_4$ and $N_2O$ among treatments. In the subsurface tile drainage plot of $11.9mm\;d^{-1}$ percolation rate, 46% of $CH_4$ and 33% of $N_2O$ emission amounts were reduced in comparison of non-subsurface drainage plot of $6.9mm\;d^{-1}$ percolation rate. With rice straw application, the $CH_4$ emission amount was 2.1 times to that from no-applied plot, the $N_2O$ emission amount was not affected by rice straw application.

• Journal of Korean Philosophical Society
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• v.145
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• pp.195-215
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• 2018

Plato said that our cosmos was created from the union of nous and $anank{\bar{e}}$ in Timaeus. In addition to this, 'the third kind', namely $ch{\bar{o}}ra$, exists already with genesis before the birth of the cosmos. Plato explains this $ch{\bar{o}}ra$ with several metaphors. That is, 'receptacle', 'mother', 'gold', 'space', 'place' etc. From Aristotle to contemporary scholars, generally three types of interpretations are presented. First, $ch{\bar{o}}ra$ is a kind of a 'void.' Secondly, $ch{\bar{o}}ra$ is Aristotle's $prot{\bar{e}}$ $hyl{\bar{e}}$. Thirdly, $ch{\bar{o}}ra$ has two aspects of space and matter. I will accept the third opinion. Plato's $ch{\bar{o}}ra$ has both a spatial aspect and material aspect. $Ch{\bar{o}}ra$ is a place that accommodates all sensible things in itself. On the other hand, $ch{\bar{o}}ra$ seems to be a mother who nourishes sensible things like a child. In this, Plato lacks a logical consistency. The research of $ch{\bar{o}}ra$ can not deviate from the limits of $eik{\bar{o}}s$ logos.

• Applied Microscopy
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• v.35 no.2
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• pp.81-87
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• 2005

To evaluate the effects of ingestion of alcoholic drinks on the toxicities of industrial compounds, cyclohexane (CH) was intraperitoneally administrated to rats (1.56 g/kg body weght), which had been ingested 15% ethanol for up to 6 weeks, 4 times by once a day and every other day. Following the last treatment of ethanol or CH, blood and lung tissues were collected during 24 hours prior to sacrifice of animals. Comparing with the control group, the lung weight per body weight (%) and the protein content in bronchoalveolar lavage fluid were increased in the ethanol-pretreated group, and the glucose-6-phosphatase activity in lung tissues was decreased in the CH-treated group. In a morphological observations, pulmonary embolus were found in the CH-treated group, whereas a partial pulmonary atelectasis and a much increase in pulmonary embolus were shown in the CH-treated group after pretreated with ethanol for 6 weeks. In conclusion, these results indicate that ethanol pretreatment could enhance CH metabolism and that CH treatment with ethanol pretreatment could induce lung injury due to the increased CH metabolism.