• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.4
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• pp.309-315
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• 2012

Catalytic combustion is generally accepted as one of the environmentally preferred alternatives for heat and power from fossil fuels, as it has the advantage of stable combustion under very lean conditions with such low emissions as UHC, CO, and NOx. In this work, therefore, comparative numerical studies on the catalytic combustion behaviors over Pd-based catalysts have been conducted with the gaseous $CH_4$, $C_2H_6$, and $C_3H_8$. In the following, after introducing the governing equations with 1D channel and Langmuir-Hinshelwood models, numerical investigations on the catalyst performance are conducted by changing such various parameters as inlet temperature, excess air ratio, and space velocity. The numerical results show that outlet temperature and conversion of $C_3H_8$ are highest among others because of its chemical structure and reactivity.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.107-113
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• 2004

Several transition metal complexes, [$M(L)X_2$](M=Pd(II), Ni(II); X=CI, Br) are prepared with aminophosphine ligands such as 1,2-bis{(diphenylphosphino)amino}ethane{$Ph_2PNHCH_2CH_2NHPPh_2$}($L_1$), 1,2-bis{(diphenylphosphino)amino}propane{$Ph_2PNHCH(CH_3)CH_2NHPPh_2$}($L_2$), trans-1,2-bis{(diphenylphosphino)amino}cyclohexane{$Ph_2PNHC_6H_{10}NHPPh_2$}($L_3$) and 1,2-bis{(diphenylphosphino)amino}benzene{$Ph_2PNHC_6H_4NHPPh_2$}($L_4$). The properties of these complexes are characterized by optical spectroscopic methods including UV/vis spectroscopy, CD, IR, $^1H$- and $^{31}P-NMR$ together with conductometer and elemental analysis. All complexes are stable under atmospheric environment. Catalytic reactivity for C-C coupling between [$M(L)X_2$] and Grignard reagents(RMgX; R=phenyl, propyl, buthyl) by thermolysis were investigated utilizing GC/mass, $^1H$- and $^{13}C-NMR$. When mol scale is 1:20 at [$Pd(L)Cl_2$] and Grignard reagents, the high catalytic activity for C-C coupling is apparent. The [$M(L)X_2$](X=Cl, Br) complexes which have strong bond at M-P exhibit high yields for C-C coupling reactions. When the central metal ion is Pd(II), the high catalytic activity for C-C coupling is apparent. The complex coordinated with Br shows higher catalytic activity for C-C coupling reactions compared to Cl.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.84-89
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• 2007

Direct decomposition of hydrocarbon (methane, propane) was studied using a thermal plasma to produce high purity hydrogen and carbon black. Thermodynamic equilibrium compositions were calculated based on the minimization of Gibb's free energy, and decomposition experiments were performed on the basis of calculation results. The purity of hydrogen was found to be depended strongly on the flow rate of hydrocarbon. The decomposition conditions for high purity hydrogen were investigated. The purity of hydrogen produced from methane decomposition was higher than that from propane. In the case of propane, it was investigated that by products such as methane, acetylene, and ethane etc., by radical recombination under thermal plasma were produced more than that of methane. Produced carbon blacks were characterized by material analyses, such as XRD, Raman spectroscopy, SEM, and particle size analysis. In both methane and propane decompositions, well-crystallized carbon blacks were produced and showed uniform and sphere-like morphologies. The size of carbon black synthesized from methane was observed to be smaller than that from propane.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.266-273
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• 2008

Natural gas hydrates are ice-like solid substances, which are composed of water and natural gas, mainly methane. They have three kinds of crystal structures of five polyhedra formed by hydrogen-bonded water molecules, and are stable at high pressures and low temperatures. They contain large amounts of organic carbon and widely occur in deep oceans and permafrost regions. Therefore, they are expected as a potential energy resource in the future. Especially, $1m^3$ natural gas hydrate contains up to $172Nm^3$ of methane gas, de pending on the pressure and temperature of production. Such large volumes make natural gas hydrates can be used to store and transport natural gas. In this study, three-phase equilibrium conditions for forming natural gas hydrate were numerically obtained in pure water and single electrolyte solution containing 3 wt% NaCl. The results show that the predictions match the previous experimental values very well, and it was found that NaCl acts as an inhibitor. Also, help gases such that ethane, propane, i-butane, and n-butane reduce the hydrate formation pressure at the same temperature.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2303-2308
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• 2009

A thiocyanate poly(vinyl chloride) (PVC) membrane electrode based on [1,2-bis(diphenylphosphino)ethane]dihalopalladium( II), [(dppe)$PdX_2$, X = Cl ($L^1$), X = I ($L^2$)] as active sensor has been developed. The diiodopalladium complex, [(dppe)$PdI_2](L^2$) displays an anti-Hofmeister selectivity sequence: $SCN^-\;>\;I^-\;>\;{ClO_4}^-\;>\;Sal^-\;>\;Br^-\;>\;{NO_2}^-\;>\;{HPO_4}^-\;>\;AcO^-\;>\;{NO_3}^-\;>\;{H_2PO_4}^-\;>\;{CO_3}^{2-}$. The electrode exhibits a Nernstian response (-59.8 mV/decade) over a wide linear concentration range of thiocyanate ($(1.0\;{\times}\;10^{-1}\;to\;5.0\;{\times}\;10^{-6}$ M), low detection limit ($(1.1\;{\times}\;10^{-6}$ M), fast response $(t_{90%}$ = 24 s), and applicability over a wide pH range (3.5∼11). Addition of anionic sites, potassium tetrakis[p-chlorophenyl] borate (KTpClPB) is shown to improve potentiometric anion selectivity, suggesting that the palladium complex may operate as a partially charged carrier-type ionophore within the polymer membrane phase. The reaction mechanism is discussed with respect to UV-Vis and IR spectroscopy. Application of the electrode to the potentiometric titration of thiocyanate ion with silver nitrate is reported.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.3
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• pp.357-364
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• 1999

We investigated the role of $Ca^{2+}$ and protein kinases/phosphatases in the stimulatory effect of insulin on glucose transport. In isolated rat adipocytes, the simple omission of $CaCl_2$ from the incubation medium significantly reduced, but did not abolish, insulin-stimulated 2-deoxy glucose (2-DG) uptake. Pre-loading adipocytes with intracellular $Ca^{2+}$ chelator, 5,5'-dimethyl bis (o-aminophenoxy)ethane-N,N,N'N' tetraacetic acetoxymethyl ester (5,5'-dimethyl BAPTA/AM) completely blocked the stimulation. Insulin raised intracellular $Ca^{2+}$ concentration $([Ca^{2+}]_i)$ about 1.7 times the basal level of $72{\pm}5$ nM, and 5,5'-dimethyl BAPTA/AM kept it constant at the basal level. This correlation between insulin-induced increases in 2-DG uptake and $[Ca^{2+}]_i$ indicates that the elevation of $[Ca^{2+}]_i$ may be prerequisite for the stimulation of glucose transport. Studies with inhibitors (ML-9, KN-62, cyclosporin A) of $Ca^{2+}-calmodulin$ dependent protein kinases/phosphatases also indicate an involvement of intracellular $Ca^{2+}.$ Additional studies with okadaic acid and calyculin A, protein phosphatase-1 (PP-1) and 2A (PP-2A) inhibitors, indicate an involvement of PP-1 in insulin action on 2-DG uptake. These results indicate an involvement of $Ca^{2+}-dependent$ signaling pathway in insulin action on glucose transport.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.3
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• pp.283-291
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• 1999

We have synthesized novel platinum (II) coordination complex containing cis-1,2-diaminocyclohexane (DACH) as a carrier ligand and 1,2-bis(diphenylphosphino)ethane (DPPE) as leaving group. Furthermore, nitrate was added to improve the water-solubility. A new series of [Pt(cis-DACH)(DPPE)] $2NO_3(PC)$ was evaluated its antitumor activity on various MKN-45 human gastric adenocarcinoma cell-lines and normal primary cultured kidney cells. The new platinum complex demonstrated high efficacy in the cytotoxicity on MKN-45 cell-lines as well as adriamycin-resistant (MKN-45/ADR) and cisplatin-resistant (MKN-45/CDDP) cells. The cytotoxicities of PC were found quite less than those of cisplatin in rabbit proximal renal tubular cells, human renal cortical cells and human renal cortical tissues using MTT assay, $[^3H]-thymidine$ uptake and glucose consumption tests. Based on these results, this novel platinum (II) coordination complex, was considered as better a valuable lead for improving antitumor activities with low nephrotoxicities in the development of a new clinically available anticancer chemotherapeutic agents.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.259-264
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• 2011

Gas hydrate is formed by physical binding between water molecule and gas such as methane, ethane, propane, or carbon dioxide, etc., which is captured in the cavities of water molecule under the specific temperature and pressure. $1\;m^3$ hydrate of pure methane can be decomposed to the methane gas of $172\;m^3$ and water of $0.8\;m^3$ at standard condition. If this characteristic of hydrate is reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store of natural gas in large quantity. Especially the transportation cost is known to be 18~25% less than the liquefied transportation. However, when methane gas hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. Therefore, for the practical purpose in the application, the present investigation focuses on the rapid production of hydrates and the increment of the amount of captured gas by adding zeolite into pure water. The results show that when the zeolite of 0.01 wt% was added to distilled water, the amount of captured gas during the formation of methane hydrate was about 4.5 times higher than that in distilled water, and the methane hydrate formation time decreased at the same subcooling temperature.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1615-1620
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• 2010

Bis-[dipyrido[3,2-$\alpha$:2',3'-c]phenazine)$_2$(1,10-phenanthroline)$_2Ru_2$]$^{2+}$ complexes (bis-Ru(II) complexes) tethered by linkers of various lengths were synthesized and their binding properties to DNA investigated by normal absorption and linear dichroism spectra, and fluorescence techniques in this study. Upon binding to DNA, the bis-Ru(II) complex with the longest linker (1,3-bis-(4-pyridyl)-propane), exhibited a negative $LD^r$ signal whose intensity was as large as that in the DNA absorption region, followed by a complicate $LD^r$ signal in the metal-to-ligand charge transfer region. The luminescence intensity of this bis-Ru(II) complex was enhanced. The observed $LD^r$ and luminescence results resembled that of the [Ru(1,10-phenanthroline)$_2$ dipyrido[3,2-$\alpha$:2',3'-c]phenazine]$^{2+}$ complex, whose dipyrido[3,2-$\alpha$:2',3'-c]phenazine (dppz) ligand has been known to intercalate between DNA bases. Hence, it is conclusive that both dppz ligands of the bis-Ru(II) complex intercalate. The binding stoichiometry, however, was a single intercalated dppz per ~ 2.3 bases, which violates the "nearest binding site exclusion" model for intercalation. The length between the two Ru(II) complexes may be barely long enough to accommodate one DNA base between the two dppz ligands, but not for two DNA bases. When the linker was shorter (4,4'-bipyridine or 1,2-bis-(4-pyridyl)-ethane), the magnitude of the LD in the dppz absorption region, as well as the luminescence intensity of both bis-Ru(II) complexes, was half that of the bis-Ru(II) complex bearing a long linker. This observation can be elucidated by a model whereby one of the dppz ligands intercalates while the other is exposed to the aqueous environment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1025-1031
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• 2011

Autoignition characteristic is an important parameter for designing diesel or PCCI engines. In particular, diesel spray flames are lifted from the nozzle and the initial flame is formed by an autoignition phenomenon. The lifted nature of diesel spray flames influences soot formation, since air will be entrained into the spray core by the entrainment of air between the nozzle region and the lifted flame base. The objective of the present study was to identify the effect of heat loss on the ignition delay time by adopting a coflow jet as a model problem. Methane ($CH_4$), ethylene ($C_2H_4$), ethane ($C_2H_6$), propene ($C_3H_6$), propane ($C_3H_8$), and normal butane (n-$C_4H_{10}$) fuels were injected into high temperature air, and the liftoff height was measured experimentally. As the result, a correlation was determined between the liftoff height of the autoignited lifted flame and the ignition delay time considering the heat loss to the atmosphere.