• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.317-318
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• 2023

This study is part of the carbonation degree DB accumulation through quantitative analysis of carbonation depth, Ca(OH)₂ and CO₂ according to the type of finish and years of use of old concrete structures in order to predict the amount of CO₂ that can be absorbed through carbonation of concrete. To this end, the depth of carbonation of the concrete core specimen is measured using an indicator, and the dry amount of water combined with CO₂ in the sample is measured using a differential thermal gravimetric analyzer for samples in the carbonation area and non-carbonated area classified by the indicator, and the absorption compared to the weight of the sample. The amount of absorbed CO₂ was calculated. In addition, the degree of carbonation was calculated through quantitative comparison of Ca(OH)₂ in the carbonation section and non-carbonation section. In the future, we will continue to add the survey and analysis data of dismantled structures and use them as basic data for estimating the amount of carbon dioxide that can be absorbed according to the exposure conditions and years of use by concrete mix.

• Archives of Pharmacal Research
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• v.7 no.1
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• pp.47-52
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• 1984

Four polymorphic forms (I, II, III and IV) of hydrochlorothiazide have been characterized on the basis of x-ray diffractometry and differential thermal analysis. Form I was obtained by crystallization from N, N-dimethylformamide and Form II was crystallized from hot methanol. Form III was precipitated from sodium hydroxide aqueous solution by treatment with hydrochloric acid and Form IV was crystallized from 50% methanol. The metastable form I was a most stable form among four polymorphs, which was stable more than ten months at room temperature. The thermodynamic parameters such as heat of solution, enthalpy, entropy, free energy difference and transition temperature were determined by the measurement of intrinsic dissolution rate. The transition temperature and the heat of transition between the metastable Form I an Form II were determined to be $299.15^{\circ}$K and 5.03 Kcal/mole, respectively and free energy difference ($\delta$ F) was 302. 13 cal/mole. Diuretic action of these four polymorphic forms was also evaluated by monitoring the difference in urinary excretion of sodium, potassium and magnesium in rats.

• Electrical & Electronic Materials
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• v.9 no.5
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• pp.450-454
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• 1996

Maxwell-Displacement-Current(MDC) measuring technique has been applied to the study of monolayers of Dilauroylphosphatidylcholine (L-.alpha.-DLPC) and Dimyristoylphosphatidylcholine (L-.alpha.-DMPC). The displacement current was generated from monolayers on a water surface by monolayer compression. Displacement current was generated when the area per molecule was about 250.angs.$^{2}$, 280.angs.$^{2}$. Displacement current was generated in the gas state, gas/liquid state, and liquid state in the course of monolayer compression. The orientational change of molecules in monolayers was discussed on the basis of the MDCs obtained. Finally, we measured differential thermal analysis of sample.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.545-548
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• 2002

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3$(BSCT) (x=0.10, 0.15, 0.20) powders were prepared by the sol-gel method and BSCT thick films were fabricated by the screen-printing method. The structural properties as a faction of the composition ratio were studied. As a result of the differential thermal analysis (DTA), exothermic perk was observed at around $860^{\circ}C$ dne to the formation of the polycrystalline perovskite phase. The BSCT thick films sintered at $1350^{\circ}C$ for 2h showed the average grain size of $2{\sim}7{\mu}m$. The average thickness of BSCT thick films, obtained by 3 times of screen-printing, was approximately $85{\mu}m$.

• Steel and Composite Structures
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• v.27 no.6
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• pp.777-788
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• 2018

An investigation on the thermal buckling resistance of simply supported FGM beams having parabolic-concave thickness variation and temperature dependent material properties is presented in this paper. An analytical formulation based on the first order beam theory is derived and the governing differential equation of thermal stability is solved numerically using finite difference method. a function of thickness variation is introduced which controls the parabolic variation intensity of the beam thickness without changing its original material volume. The results showed the high importance of taking into account the temperature-dependent material properties in the thermal buckling analysis of such critical beam sections. Different Influencing parametric on the thermal stability are studied which may help in design guidelines of such complex structures.

• Steel and Composite Structures
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• v.51 no.2
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• pp.139-151
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• 2024

In this research, a semi-analytical solution is presented for computing mechanical displacements and thermal stresses in rotating thick cylindrical pressure vessels made of functionally graded material (FGM). The modulus of elasticity, linear thermal expansion coefficient, and density of the cylinder are assumed to change along the axial direction as a power-law function. It is also assumed that Poisson's ratio and thermal conductivity are constant. This cylinder was subjected to non-uniform internal pressure and thermal loading. Thermal loading varies in two directions. The governing equations are derived by the first-order shear deformation theory (FSDT). Using the multilayer method, a functionally graded (FG) cylinder with variable thickness is divided into n homogenous disks, and n sets of differential equations are obtained. Applying the boundary conditions and continuity conditions between the layers, the solution of this set of equations is obtained. To the best of the researchers' knowledge, in the literature, there is no study carried out bi-directional thermoelastic analysis of clamped-clamped rotating FGM thick-walled cylindrical pressure vessels under variable pressure in the longitudinal direction.

• Journal of the Mineralogical Society of Korea
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• v.12 no.1
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• pp.11-22
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• 1999

Thermal behavior of dickite was studied by thermal analysis, X-ray diffraction analysis, electron microprobe analysis, and scanning electron microscopy, Dickite has an endothermic peak at about$ 650^{\circ}C$ and an exothermic one at $960^{\circ}C$ in the differential thermal analysis. The endothermic reaction is assigned to the decomposition of dickite to meta-dickite. Hydroxyl radicals are removed from dickite structure by the reaction, resulting in the weight loss about 10.5~14.5% and appearance of a 14$\AA$ phase different from other kaolin minerals. The reaction slowly proceed in the range of $200^{\circ}C$. As the completion of decomposition, aciclular mullite forms at the expense of meta-dickite plates with random crystallographic relationship. Mullites have diverse silica versus alumina ratio. The exothermic reaction without weight loss seems to be due to the formation of spinel and amorphous silica. The spinel phase shows cryptocrystalline globular morphology accompanying a little amount of silica. From spinel phase shows cryptocrystalling globular morphology accompanying a little amount of silica. From this work, it is suggested that mullite is formed from meta-dickite much lower temperature than the reported one in the previous works.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.15-21
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• 2015

The thermal decomposition characteristics of the ZPP(Zirconium/Potassium perchlorate), widely used as a primary charge of initiators, were investigated by differential scanning calorimetry(DSC). The DSC results with different heating rates were elaborated with AKTS-Thermokinetics software for the determination of the kinetic parameters of the thermal decomposition of ZPP. There was good agreement between the experimental and the simulation curves, based on the determined kinetic parameters, which indicates the validity of the kinetic description of the thermal decomposition process of ZPP.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1680-1688
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• 2017

In this study, analysis is performed on entropy generation during cilia transport of water based titanium dioxide nanoparticles in the presence of viscous dissipation. Moreover, thermal heat flux is considered at the surface of a channel with ciliated walls. Mathematical formulation is constructed in the form of nonlinear partial differential equations. Making use of suitable variables, the set of partial differential equations is reduced to coupled nonlinear ordinary differential equations. Closed form exact solutions are obtained for velocity, temperature, and pressure gradient. Graphical illustrations for emerging flow parameters, such as Hartmann number (Ha), Brinkmann number (Br), radiation parameter (Rn), and flow rate, have been prepared in order to capture the physical behavior of these parameters. The main goal (i.e., the minimizing of entropy generation) of the second law of thermodynamics can be achieved by decreasing the magnitude of Br, Ha and ${\Lambda}$ parameters.

• Journal of Welding and Joining
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• v.24 no.2
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• pp.57-63
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• 2006

In this study, the curing kinetics and thermal degradation of underfill were investigated using differential scanning calorimetry (DSC) and thermo gravimetry analysis (TGA). The mechanical and thermal properties of underfill were characterized using dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). Also, we presented on underfill dispensing process using Prostar tool. The non-isothermal DSC scans at various heating rates, the exothermic reaction peak became narrower with increasing the heating rate. The thermal degradation of underfill was composed of two processes, which involved chemical reactions between the degrading polymer and oxygen from the air atmosphere. The results of fluidity phenomena were simulated using Star CD program, the fluidity of the underfills with lower viscosity was faster.