• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2257-2262
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• 2014

$C_{60}$ is widely investigated because of its unique structure. But its applications in solid propellant seem to be relatively neglected. $C_{60}$ has more outstanding features than carbon black which is widely used as a catalyst ingredient of solid propellant. To combine the advantages of fullerene and lead salts, another good composite in propellant catalysts, we synthesized a kind of fullerene phenylalanine lead salt (FPL) and explored its thermal performances by differential thermal analysis (DTA) and thermogravimetry analysis (TGA). The results show it undergoes four exothermic processes started from 408 K. Combined TGA and X-ray diffractometer (XRD), the decomposition mechanism of FPL was derived by TG-IR and comparing IR spectra of FPL and its residues after burned to $327^{\circ}C$, $376^{\circ}C$ and $424^{\circ}C$, respectively. Effect of FPL on the decomposition characteristic of hexogen (RDX), a type of explosive in propellant, has been investigated using DTA at different heating rate, which shows the decomposition temperatures of the explosive are all reduced by more than 20 K. The corresponding activation energy ($E_a$) is decreased by $30kJ{\cdot}mol^{-1}$. So FPL has potential application as a combustion catalyst in solid propellant.

• 대한화학회지
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• 제33권6호
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• pp.662-668
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• 1989

Metal-4,4',4",4"'-tetraaminophthalocyanine [Mt-$PcNH_2$, Mt = Fe(III), Co(II), Ni(II), Cu(II)] 및 Mt-$PcNH_2$가 styrene-methacrylic acid 공중합체(STMA)에 고정화된 Mt-PcSTMA를 촉매로 사용한 불균일 수용액계에서 과산화수소의 분해반응에 대한 촉매활성에 대하여 실험하였다. 이 촉매들은 효소반응과 비슷한 촉매활성을 나타내었고, Fe(III)-$PcNH_2$이 공중합체에 결합되어 고정화된 Fe(III)-PcSTMA가 가장 촉매활성이 우수하였다. 분해반응율은 높은 pH 범위에서 증가하였으며, $CN^-,\;CNS^-,\;{C_2O_4}^{-2},\;I^-$ 등의 공존 음이온의 영향을 받았다. 또한, 반응속도론적인 고찰을 통하여 열역학적 특성값을 구한 결과로부터 촉매반응이 Michaelis-Menten형의 반응기구로 진행됨을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제17권7호
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• pp.637-642
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• 1996

Preparation and properties of potential CVD (Chemical Vapor Deposition) precursors for the TiO2, a major component of the perovskite materials such as PT, PLT, PZT, and PLZT were investigated. Reactions between β-diketones and TiMe3, formed in situ failed to produce stable Ti(β-diketonate)3 complexes but a stable purple solid, characterized as (OTi(BPP)2)2 (BPP=1,3-biphenyl-1,3-propanedione) was obtained when BPP was used. Several new Ti(Oi-Pr)2(β-diketonate)2 complexes with aromatic or ring substituents were synthesized by the substitution reaction of Ti(OiPr)4by β-diketones and characterized with 1H NMR, IR, ICP, and TGA. Solid complexes such as Ti(Oi-Pr)2(BAC)2 (BAC=1.-phenyl-2,4-pentanedione), Ti(Oi-Pr)2(BPP)2, Ti(Oi-Pr)2(1-HAN)2 (1-HAN=2-hydroxy-1-acetonaphthone), Ti(Oi-Pr)2(2-HAN)2 (2-HAN=1-hydroxy-2-acetonaphthone), Ti(Oi-Pr)2(ACCP)2 (ACCP=2-acetylcyclopentanone), and Ti(Oi-Pr)2(HBP)2 (HBP=2-hydroxybenzophenone) were found to be stable toward moisture and air. Ti(Oi-Pr)2(ACCP)2 and Ti(Oi-Pr)2(HBP)2 were proved to have lower melting points and higher decomposition temperatures. However, these complexes are thermally stable and pyrolysis under an inert atmosphere resulted in incomplete decomposition. Ti(Oi-Pr)2(DPM)2 (DPM=dipivaloylmethane) and Ti(Oi-Pr)2(HFAA)2 (HFAA=hexafluoroacetylacetone) were sublimed substantially during the thermal decomposition. Pyrolysis mechanism of these complexes are dependent on type of β-diketone but removal of Oi-Pr ligands occurs before the decomposition of β-diketonate ligands.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.23-35
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• 2017

A nonlinear static procedure considering work-energy principle and global failure mechanism to estimate base shears of reinforced concrete (RC) frame-type structures is presented. The relative energy equation comprising of elastic vibrational energy, plastic strain energy and seismic input energy is obtained. The input energy is modified with a factor depending on damping ratio and ductility, and the energy that contributes to damage is obtained. The plastic energy is decreased with a factor to consider the reduced hysteretic behavior of RC members. Given the pre-selected failure mechanism, the modified energy balance equality is written using various approximations for modification factors of input energy and plastic energy in scientific literature. External work done by the design lateral forces distributed to story levels in accordance with Turkish Seismic Design Code is calculated considering the target plastic drift. Equating the plastic energy obtained from energy balance to external work done by the equivalent inertia forces considering, a total of 16 energy-based base shears for each frame are derived considering different combinations of modification factors. Ductility related parameters of modification factors are determined from pushover analysis. Relative input energy of multi degree of freedom (MDOF) system is approximated by using the modal-energy-decomposition approach. Energy-based design base shears are compared with those obtained from nonlinear time history (NLTH) analysis using recorded accelerograms. It is found that some of the energy-based base shears are in reasonable agreement with the mean base shear obtained from NLTH analysis.

• Macromolecular Research
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• 제14권5호
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• pp.491-498
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• 2006

The thermal degradation of poly(hexamethylene guanidine) phosphate (PHMG) was studied by dynamic thermogravimetric analysis (TGA) and pyrolysis-GC/MS (p-GC). Thermal degradation of PHMG occurs in three different processes, such as dephosphorylation, sublimation/vaporization of amine compounds and decomposition/ recombination of hydrocarbon residues. The kinetic parameters of each stage were calculated from the Kissinger, Friedman and Flynn-Wall-Ozawa methods. The Chang method was also used for comparison study. To investigate the degradation mechanisms of the three different stages, the Coats-Redfern and the Phadnis-Deshpande methods were employed. The probable degradation mechanism for the first stage was a nucleation and growth mechanism, $A_n$ type. However, a power law and a diffusion mechanism, $D_n$ type, were operated for the second degradation stage, whereas a nucleation and growth mechanism, $A_n$ type, were operated again for the third degradation stage of PHMG. The theoretical weight loss against temperature curves, calculated by the estimated kinetic parameters, well fit the experimental data, thereby confirming the validity of the analysis method used in this work. The life-time predicted from the kinetic equation is a valuable guide for the thermal processing of PHMG.

• 대한약리학회지
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• 제23권1호
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• pp.25-31
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• 1987

$Cu^{++}$ 촉매작용에 의한 과산화현상이 관절조직손상의 한 형태인 Collagen 손상에 관여할 수 있음을 알아보고, sodium salicylate의 항 염증기전의 일부를 설명해 보고자 sodium salicylate가 이 과산화반응에 미치는 효과를 검토하였다. 쥐피부로 부터 얻은 Collagen을 이용하여 Collagen gelation에 대한 $Cu^{++}$와$H_2O_2$의 효과를 관찰한 결과 $Cu^{++}$ 또는 $H_2O_2$ 단독으로는 gelation에 영향을 미치지 못하였으나, $Cu^{++}$와 $H_2O_2$가 동시에 첨가된 경우 gelation이 억제되어 maximal turbidity가 감소되고, lag phase가 연장됨을 보였다. 그리고 같은 반응 조건에서 sodium salicylate 첨가에 의해 $Cu^{++}$와 $H_2O_2$에 의해 억제된 gelation이 회복됨을 볼 수 있었으며 회복정도는 salicylate 농도 증가에 의존적이었다. 한편 $Cu^{++}$에 의한 $H_2O_2$의 decomposition rate가 sodium salicylate에 의해 증가됨을 보였고, salicylate 농도 증가에 의해 점차 saturation되는 양상을 보였다. 이상의 결과로 부터 $Cu^{++}$ 촉매작용에 의한 과산화 현상은 collagen에 작용하여 구조적 또는 기능적인 변화를 초래함을 알 수 있었고, salicylate에 의해 이러한 과산화 현상이 억제되는 것은 $Cu^{++}$에 의한 $H_2O_2$의 decomposition rate를 증가시킨 결과임을 알 수 있었다. 그러므로 $Cu^{++}$ 촉매작용에 의한 과산화현상은 만성염증 반응 특히 rheumatoid arthritis에서 나타나는 관절조직 손상에 관여할 수 있으며, sodium salicylate는 이 과산화반응에 작용하여 항 염증효과를 나타낼 수 있으리라 믿어졌다.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 2002년도 Language, Information, and Computation Proceedings of The 16th Pacific Asia Conference
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• pp.113-122
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• 2002

Following Herburger (2000), I will develop an event-based semantics for Japanese emphatic particles which can address the issue of the mechanism of association with focus involving the emphatic particles. The proposed semantics makes use of Herburger's three key ideas: events as basic entities, decomposition of predicates into subatomic formulas, and separation of backgrounded and foregrounded information.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.559-564
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• 1993

Nonlinear equation of motion of the flexible manipulator are derived by the Lagrangian method in symbolic form to better understand the structure of the dynamic model. The resulting equations of motion have a structure which is useful to reduce the number of terms calculated, to check correctness, or to extend the model to high order. A manipulator with a flexible 4 bar link mechanism is a constrained system whose equations are sensitive to numerical integration error. This constrained system is solved using the null space matrix of the constraint Jacobian matrix. Singular value decomposition is a stable algorithm to find the null space matrix.

• Tribology and Lubricants
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• 제11권5호
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• pp.1-9
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• 1995

The mechanism of various spherical particles formation from wide range of tribo-systerns is suggested and deduced by the action of micro-explosion on the basis of the thermally-activated wear theory, in which the flash temperature at contact could be reached clearly upto the material molten temperature due to the secondary activation energy from the exothermic reactions involving lubricant thermo-decomposition, metals oxidation, hydrogen reactions and other possible complex thermo-reactions at the contacts. Various shapes of spherical particles generated from the tribosystem can be explained by the toroidal action of micro-explosion accompanied with the complex thermo-chemical reactions at the contact surfaces or sub-surfaces.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.243-245
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• 2013

Rate equations are exactly solved for the reversible consecutive reaction of the first-order and the time-dependence of concentrations is analytically determined for species in the reaction. With the assumption of pseudo first-order reaction, the calculation applies and determines the concentration of product accurately and explicitly as a function of time in the unimolecular decomposition of Lindemann and in the enzyme catalysis of Michaelis-Menten whose rate laws have been approximated in terms of reactant concentrations by the steady-state approximation.