• Journal of the Korean Chemical Society
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• v.10 no.2
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• pp.103-108
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• 1966

The effect of temperature on the critical micelle concentration of dodecylpyridinium chloride has been determined by electrical conductance method over the range from $5^{\circ}C\;to\;50^{\circ}C$. The values of the change in heat content, ${\Delta}H_m$, and the other thermodynamic parameters have been estimated using the equation of temperature dependence on the critical micelle concentration for the same temperature range. The significance of these thermodynamic quantities and their relations to the various current theories of micelle forming processes were discussed.

• Journal of Korea Foundry Society
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• v.25 no.1
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• pp.36-39
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• 2005

The thermodynamic analysis of deoxidation in molten coppyr by Fe has been made. Equilibrium oxygen solubility saturated with FeO in Cu-Fe-O system has been derived without and with consideration of the solute interaction between Fe and O. The derived relationship of oxygen contents with Fe has been compared with the experimental results done by Kulkarni and the minimum oxygen solubility could be predicted by a simple first order interaction method, Wagner model.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.6
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• pp.265-270
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• 2002

The determination of DNA hybridization reaction can apply the molecular biology research, clinic diagnostics, bioengineering, environment monitoring, food science and application area. So, the improvement of DNA hybridization detection method is very important for the determination of this hybridization reaction. Several molecular biological techniques require accurate predictions of matched versus mismatched hybridization thermodynamics, such as PCR, sequencing by hybridization, gene diagnostics and antisense oligonucleotide probes. In addition, recent developments of oligonucleotide chip arrays as means for biochemical assays and DNA sequencing requires accurate knowledge of hybridization thermodynamics and population ratios at matched and mismatched target sites. In this study, we report the characteristics of the probe and matched, mismatched target oligonucleotide hybridization reaction using thermodynamic method. Thermodynamic of 5 oligonucleotides with central and terminal mismatch sequences were obtained by measured UV-absorbance as a function of temperature. The data show that the nearest-neighbor base-pair model is adequate for predicting thermodynamics of oligonucleotides with average deviations for $\Delta$H$^{0}$ , $\Delta$S$^{0}$ , $\Delta$G$_{37}$ $^{0}$ and T$_{m}$, respectively.>$^{0}$ and T$_{m}$, respectively.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.10-14
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• 2003

This paper deals with the design of heat dissipation system using the forced air cooling method. It suggests the method of appropriately dividing the whole thermodynamic system into analytical subsystems and also presents the correspondent analytic or experimental equations to subsystems. The experimental results on the designed thermodynamic system for 400kw 1GBT inverter show the validity of the proposed design method in the steady state.

• Journal of Korea Foundry Society
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• v.41 no.5
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• pp.445-453
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• 2021

Computational thermodynamics for various alloy systems is well known as the CALPHAD technique. Gibbs energy model parameters for each phase are obtained from experimentally measured thermodynamic properties and are mainly used to predict areas not experimentally measured and to analyze experimental results thermodynamically. In this study, the thermodynamic modeling of the Ni-Cr-Nb-C quaternary system is conducted for a thermodynamic analysis of the phenomena by which heat-resistant cast alloys (IN-657) are destroyed in certain areas after long-term use. The stable phases in the system according to the Cr content, phase fraction depending on the temperature, and long-range ordering parameters for the Ni₂Cr phase are calculated and compared to results obtained experimentally. The calculated thermodynamic properties suitably explain the experimentally reported fracture temperature range and the results of stable phases formed in the fractured areas. Thermodynamic modeling through the CALPHD method is expected to be useful for analyzing and predicting the thermodynamic behaviors of various cast alloys.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1475-1482
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• 2006

Wet compression means the injection of water droplets into the compressor of gas turbines. This method decreases the compression work and increases the turbine output by decreasing the compressor exit temperature through the evaporation of water droplets inside the compressor. Researches on wet compression, up to now, have been focused on the thermodynamic analysis of wet compression where the decrease in exit flow temperature and compression work is demonstrated. This paper provides thermodynamic and aerodynamic analysis on wet compression in a centrifugal compressor for a microturbine. The meanline dry compression performance analysis of centrifugal compressor is coupled with the thermodynamic equation of wet compression to get the meanline performance of wet compression. The most influencing parameter in the analysis is the evaporative rate of water droplets. It is found that the impeller exit flow temperature and compression work decreases as the evaporative rate increases. And the exit flow angle decreases as the evaporative rate increases.

• Journal of the Korean Chemical Society
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• v.3 no.1
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• pp.3-8
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• 1954

Fowler obtained thermodynamic quantities assuming the theory which could be derived by representing the system with microcanonical ensemble, in order to introduce the temperature T of the system proper, he considered the combined systems which are composed of the system proper and another arbitrary system that is in thermal contact with the former, and represented the combined system by a microcanonical ensemble, here, he used the steepest descent method in his calculation. This Fowler's treatment is not only unsatisfactory at the point of theoretical view but also he could not make the formulation of free energy of Helmholtz's so that this formular was forced to be assumed. From the point of Quantum Statistical Mechanical view, the materially closed system which is in an equilibrium state with the temperature T is best represented by canonical ensemble. At the actual derivation of the distribution law and thermodynamic quantities, however, in order to avoid the difficulty of calculation Tolman proceeded his calculation either representing the system proper by the grand-canonical ensemble or adding a certain limitation.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.361-366
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• 2011

By using Monte Carlo simulation method we developed a new molecular simulation software which can be used to predict the thermodynamic properties of organic compounds. Starting from molecular structure and intermolecular potential function, rigorous statistical mechanical principles give a probability distribution for the behavior of a system containing many molecules, which enables us to calculate macroscopic thermodynamic properties of the system. The software developed in this work, cheMC, is based on Windows platform providing with easy access. One can efficiently administrate simulations by using an intuitive interface equipped with visualization tool and chart generation. It is expected that molecular simulations supplement the equation of state approach and will play a more important role in the study of thermodynamic properties.

• Korean Journal of Materials Research
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• v.20 no.1
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• pp.42-46
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• 2010

Phosphorus exhibits considerable segregation in steelmaking slag. In order to recover phosphorus from slag to $K_3PO_4$ via molten iron, a carbothermic reaction using microwave heating was suggested recently. The carbothermic reduction of phosphorus from slag to molten iron using microwave heating was carried out at 2073K. However, at this temperature the thermodynamic properties of both slag and molten iron cannot be determined experimentally. Therefore, the computational approach of the so-called CALPHAD method is very useful to understand the transfer of phosphorus from slag to metal and to enhance this reaction. In the present investigation, a theoretical study of the reduction behavior of phosphorus in slag was carried out at much lower temperatures using the recently developed thermodynamic database in the FactSage program. The calculated results showed reasonable accordance with the experimental data; namely, the thermodynamic database could be applied successfully to higher temperature reactions. The current study found that higher temperature and high $SiO_2$ concentration are favorable for the recovery of phosphorus from slag.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.413-418
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• 2011

The thermodynamic properties of steam table are obtained by measurement or approximate calculation under appropriate assumptions. Therefore they are supposed to have basic measurement errors. And thermodynamic properties should be modeled through function approximation for using in numerical analysis. In order to make noised thermodynamic properties corresponding to measurement errors, random numbers are generated, adjusted to appropriate magnitudes and added to original thermodynamic properties. Both neural networks and quadratic spline interpolation method are introduced for function approximation of these modified thermodynamic properties in the saturated water based on pressure and temperature. In analysis spline interpolation method gives much less relative errors than neural networks at both ends of data. Excluding the both ends of data, the relative errors of neural networks is generally within ${\pm}0.2%$ and those of spline interpolation method within ${\pm}0.5$~1.5%. This means that the neural networks give smaller relative errors compared with quadratic spline interpolation method within range of use. From this fact it was confirmed that the neural networks trace the original values better than the quadratic interpolation method and neural networks are more appropriate method in modelling the saturated steam table.