• Structural Engineering and Mechanics
• /
• v.9 no.2
• /
• pp.127-139
• /
• 2000

The isoparametric element method is used for a plate on non-homogenous foundation. The surface displacement due to a point force acting on the non-homogeneous foundation is the fundamental solution. Based on this analysis, the interaction between the foundation and plate can be determined and the reaction of the foundation can be treated as the external force to the plate. Therefore, only the plate needs to be divided into some elements. The method presented in this paper can be used in cases such as thin or thick plate, different plate shapes, various loading, homogenous and non-homogenous foundations. The examples in this paper show that this method is versatile, efficient and highly accurate.

• Journal of the Korean Applied Science and Technology
• /
• v.17 no.4
• /
• pp.273-278
• /
• 2000

Cellulose tosylate(CT) was prepared by reaction of cellulose with p- toluenesulfonylchloride in DMAc/LiCl homogeneous system. In order to study a reversible photoisomerization of disperse red 1(DR-1) attached on natural polymer, cellulose tosylate containing DR-1(DR-1/CT adduct) was prepared at $110^{\circ}C$ in DMAc, and the changes of UV/Vis spectra of its solutions and thick film were investigated by alternate irradiation technique. Form the UV/Vis spectra of DR-1/CT adduct dissolved in cosolvents, such as DMAc, DMAc/THF, DMAc/benzene, and DMAc/chloroform and irradiated with 360 nm and 450 nm ligths, we found out changes of UV/Vis spectra were reversible in all solvents systems and we found out changes of UV/Vis spectra were reversible at thick film, also.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.6 no.2
• /
• pp.254-262
• /
• 1996

$Pb(Zr_{0.52}Ti_{0.48})O_{3}$ (PZT) ceramics were prepared with uniform particle size of $1~3\;\mu\textrm{m}$ by hydrothermal synthesis at various conditions, such as hydrothermal reaction temperature, concentration of mineralizer and reaction time. PZT ceramics were formed above $180^{\circ}C$ for 2 hrs reaction using 10 M KOH solution as a mineralizer, but reaction condition was slightly different by starting materials. Morphology and characterization of PZT powders were investigated by XRD and SEM. By increasing the reaction temperature, KOH concentration and reaction time, the composition of the PZT phase tended to be homogeneous phase.

• Applied Chemistry for Engineering
• /
• v.2 no.2
• /
• pp.119-126
• /
• 1991

This investigation was undertaken to study the synthesis of Boehmite by the hydrothermal homogeneous precipitation reaction of alum with urea. The reactions were carried out at a temperature of 100 to $250^{\circ}C$, 1 : 2 to 1 : 5 in a mole ratio of alum to urea and a reaction time of 0.5 to 20 hrs. The reaction precipitates were examined by X-ray diffraction analysis, scanning electron microscope, and chemical analysis. Under the condition of mole ratio 1 : 4 of alum to urea, the spherical and monodispersed amorphous aluminum sulfate hydrate was formed at $100^{\circ}C$, the mixture of spherical amorphous aluminum sulfate hydrate and Boehmite was formed at $150^{\circ}C$, Boehmite was formed at above $200^{\circ}C$, respectively. The reaction precipitates were dense, superior precipitable and filterable particle of average $2-4{\mu}m$.

• Journal of Environmental Science International
• /
• v.18 no.2
• /
• pp.231-238
• /
• 2009

Characteristics of the transesterification reaction between triglycerides in soy bean oil and methanol were investigated in the presence of acid catalysts. such as sulfuric acid and PTS (p-toluene sulfonic acid). Concentrations of diglyceride and monoglyceride which were intermediates in the reaction mixtures, were far below 10% of triglyceride under any reaction conditions. Thus, conversion of the reaction could be determined from the concentration of triglyceride. Dried PTS had more superior catalytic power than sulfuric acid for transesterification reaction between soy bean oil and methanol. When transesterification reaction of soy bean oil was catalyzed by 1 wt% of PTS at methanol stoichiometric mole ratio of 2 and $65^{\circ}C$, final conversion reached 95% within 48 hours. If FAME (fatty acid methyl ester) was added into reaction mixture of soy bean oil, methanol and PTS catalyst, it converted reaction mixture into homogeneous phase, and substantially increased reaction rate. When reaction mixture was freely boiling which had equal volumetric amount of FAME to soy bean oil, methanol stoichiometric mole ratio of 2 and 1 wt% of PTS, final conversion achieved value of 94% and temperature approached to $110^{\circ}C$ within 2 hours.

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.395-398
• /
• 1989

A two dimensional pseudo-homogeneous model for the methanol reforming reaction was developed and its steady and dynamic states were studied by a computer simulation. The reactor tube diameter, the catalyst density in the fixed bed, the feed flow rate, the feed temperature and the external temperature were chosen to be adjusted to determine the length of the reactor. The dynamics of the reactor showed that the system was highly nonlinear and sensitive to the feed disturbances.

• Journal of Electrochemical Science and Technology
• /
• v.6 no.4
• /
• pp.146-151
• /
• 2015

Here I report an electrochemical simulation work that compares voltammetric current and resistance of a complex electrochemical reaction over a potential scan. For this work, the finite element method is employed which are frequently used for voltammetry but rarely for impedance spectroscopy. Specifically, this method is used for simulation of a complex reaction where a heterogeneous faradaic reaction is followed by a homogeneous chemical reaction. By tracing the current and its polarization resistance, I learn that their relationship can be explained in terms of rate constants of charge transfer and chemical change. An unexpected observation is that even though the resistance is increased by the rate of the following chemical reaction, the current can be increased due to the potential shift of the resistance made by the proceeding faradaic reaction. This report envisions a possibility of the FEM-based resistance simulation to be applied to understand a complex electrochemical reaction. Until now, resistance simulations are mostly based on equivalent circuits or complete mathematical equations and have limitations to find proper models. However, this method is based on the first-principles, and is expected to be complementary to the other simulation methods.

• Advances in Energy Research
• /
• v.4 no.4
• /
• pp.325-337
• /
• 2016

Cerbera Odollam (sea mango) is a proven promising feedstock for the production of biodiesel due to its high oil content. Fatty acid methyl esters (FAME) were produced as the final reaction product in the transesterification reflux condensation reaction of sea mango oil and methyl acetate (MA). Potassium methoxide was used as catalyst to study its reacting potential as a homogeneous base catalyst. The initial part of this project studied the optimum conditions to extract crude sea mango oil. It was found that the content of sea mango sea mango oil was 55%. This optimum amount was obtained by using 18 g of grinded sea mango seeds in 250 ml hexane. The extraction was carried out for 24 hours using solvent extraction method. Response surface methodology (RSM) was employed to determine the optimum conditions of the reaction. The three manipulated variables in this reaction were the reaction time, oil to solvent molar ratio, and catalyst wt%. The optimum condition for this reaction determined was 5 hours reaction time, 0.28 wt% of catalyst and 1:35 mol/mol of oil: solvent molar ratio. A series of test were conducted on the final FAME product of this study, namely the FTIR test, GC-FID, calorimeter bomb and viscometer test.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.32 no.8
• /
• pp.636-644
• /
• 2008

The objective of this paper is to investigate characteristics of an autothermal reformer at various operating conditions. Numerical method has been used, and simulation model has been developed for the analysis. Pseudo-homogeneous model is incorporated because the reactor is filled with catalysts of a packed-bed type. Dominant chemical reactions are Full Combustion reaction, Steam Reforming(SR) reaction, Water-Gas Shift(WGS) reaction, and Direct Steam Reforming(DSR) reaction. Simulation results are compared with experimental results for code validation. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio(OCR), Steam to Carbon Ratio(SCR), and Gas Hourly Space Velocity(GHSV). Temperature at the reactor center, fuel conversion, species at the reformer outlet, and reforming efficiency are shown as simulation results. SR reaction rate is improved by increased inlet temperature. Reforming efficiency and fuel conversion reached the maximum at 0.7 of OCR. SR reaction and WGS reaction are activated as SCR increases. When GHSV is increased, reforming efficiency increases but pressure drop from the increased GHSV may decrease the system efficiency.

• Journal of the Microelectronics and Packaging Society
• /
• v.6 no.1
• /
• pp.23-29
• /
• 1999

An yttria-stabilized zirconia(YSZ) thin film on a porous NiO-YSZ substrate for an anode support type solid oxide fuel cell(SOFC) was prepared by an electrophoretic deposition(EPD). Deposition condition and film properties in order to obtain the homogeneous YSZ thin film from the EPD solution with different polarity were studied. In different case of alcohol solution, hydrogen gas was produced in aqueous solution from the electrolyte reaction under constant current above 0.138 mA /$\textrm{cm}^2$.Its reaction generated the bubble-formed defect in the deposited film and decreased weight of the film. The homogeneous YSZ thin film was formed in alcohol solution at a constant current, 0.035 mA /$\textrm{cm}^2$ for 10 s.