• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1875-1880
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• 2010

A dicycle pyrazoline derivative, 1-phenyl-5-(p-fluorophenyl)-3,4-($\alpha$-p-fluoro-tolylenecyclohexano) pyrazoline, was synthesized and characterized by elemental analysis, IR, UV-vis, fluorescence spectra and X-ray single crystal diffraction. Density function theory (DFT) calculations were performed by using B3LYP method with 6-$311G^{**}$ basis set. The optimized geometry can well simulate the molecular structure. Vibrational frequencies were predicted, assigned and compared with the experimental values, which suggest that B3LYP/6-$311G^{**}$ method can well predict the IR spectra. Both the experimental electronic absorption spectra and the predicted ones by B3LYP/6-$311G^{**}$ method reveal three electron-transition bands, with the theoretical ones having some red shifts compared with the experimental data. Natural bond orbital analyses indicate that the absorption bands are mainly derived from the contribution of n $\rightarrow\pi^*$ and $\pi\rightarrow\pi^*$ transitions. Fluorescence spectra determination shows that the title compound can emit blue-light at about 478 nm. On the basis of vibrational analysis, the thermodynamic properties of title compound at different temperature have been calculated, revealing the correlations between $C^0_{p,m}$, $S^0_m$, $H^0_m$ and temperature.

• Journal of the Korean Chemical Society
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• v.10 no.2
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• pp.91-97
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• 1966

The partition function for liquid water is developed according to the transient state theory of significant liquid structure proposed by Pak, Ahn and Chang. This theory assumes that the molecules may possess solid-like, transient and gas-like degrees of freedom in liquid state. Although liquid water has several special properties, for example, minimum molar volume at 4^{\circ}C$, the general theory of liquid can be applied successfully. The theoretically calculated values for thermodynamic properties at the liquid temperature range and for the critical properties are in good agreement with the observed values.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.38-50
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• 1994

To improve the efficiency of internal combustion engines, it is necessary to understand mixed air-fuel in-cylinder flow processes accurately at intake and compression strokes. There is experimental and numerical methods to analyse in-cylinder flow process. In numerical method, standard $k-{\varepsilon}$ model with wall function was mostly adopted in in-cylinder flow process. But this type model was not efficiently predicted in the near wall region. Therefore in the present study, low Reynolds number $k-{\varepsilon}$ model was adopted near the cylinder wall and standard $k-{\varepsilon}$ model in other region. Also QUICK scheme was used for convective difference scheme. This study takes axisymmetric reciprocating model engine motored at 200rpm with a centrally located valve, incorporated 60 degree seat angie, and flat piston surface excluding inlet port. Because in-cylinder flow processes are undergoing unsteady and compressible, averaged cylinder pressure and inlet velocity at arbitrary crank angle are determined from thermodynamic analytic method and incylinder states at that crank angle are iteratively determined from the numerical analytic method.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.142-154
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• 1998

A stirling engine is a mechanism used to convert heat to power and operates on a closed regenerative thermodynamic cycle with compression and expansion of the working fluid at different temperature. The performance of a stilting cycle machine is a function of six independent parameters, namely; (1) speed N(r.p.m), (2) pressure of the working fluid p(Pa), (3) ratio of the temperature in the compression and expansion space ${\tau}(=T_C/T_E)$ , (4) ratio of the swept volumes in these two spaces K, (5) phase angle $\alpha$ and (6) dead volume ratio X. This paper describes the procedure and presents the results of computations carried out to establish the optimum combinations of these six parameters for maximum engine output for the machine acting as a prime mover, over a combined temperature range from $300^{\circ}K$ to $1000^{\circ}K$ and dead volume ratio X ranging from 0.1 to 2.0. The output of a stilting cycle machine can be expressed in terms of nondimensional power in several different ways. Four methods were studied in detail, the parameters optimized and design charts and engine power charts prepared. The results of this paper may be useful as a guide to the likely effects on the performance of some of the important design parameters and regenerator design.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.149-156
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• 1998

In this work, aiming at improvement of growth processes for the bulk GaAs single crystals, efforts have been made first in investigate thermodynamic properties of the Ga and As system and second to suggest that bulk GaAs crystals could be grown in principle with the single temperature zone only by determining the excess arsenic charge as a function of growth conditions. During crystal growth, this will be evaporized inside the growth chamber to induce the required inner pressure, instead of aesenic vapor pressure in the double temperature zone method, so as to be in equilibrium with the method, growth experiments have been prepared and carried out for dopes and undoped GaAs crystals with the newly built Bridgman system which was designed according to this principle. To compare the results to those of the double temperature zone method, the same numbers of GaAs crystals have been grown with both processes and all of them were characterized in single crystallinity, lattice defects and electrical properties. Especially, the relationship between growth conditions and crystal quality was discussed from the viewpoint of growth peculiarities with this method.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.349-357
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• 2004

Emergy is a measure of the processes required to produce something expressed in units of the same energy form. Emergy based indices can provide insights into the thermodynamic efficiency of the process, the quality of its output, and the interaction between the process and its surrounding environment. However, in an industrial system, the inputs are mostly nonrenewable, renewable energy source is nearly zero, ultimate purpose is pursuit of profits in economic activity. In study, we present two indices based on emergy - EEE(Ecological Economic Efficiency) and ERI(Environmental Responsibility Index). The EEE is taken into account real value of product in market economy. The ERI is shown to be a function of the net yield of the economy, its ‘load’ on the environment and ecological economic efficiency. Manufacturing industry of Korea produced the 30% of total GDP in 2001. We applied these indices to manufacturing industry for environmental management and further sustainable industry. As a results, the highest ERI is 0.34 in recycling industries, the lowest ERI is 0.01 in coke, refined petroleum products which is dominated by ELR. The higher ERI, the more friendly to environment. The suggested indices help us understand relative contributions of various alternatives in company's production and consumption activity, and provide a tool of decision-making for the rearrangement of future industries. Furthermore, they contribute to environmental friendly operation and consumption.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.127-132
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• 2003

A study of high-pressure n-heptane droplet vaporization is conducted with emphasis placed on equilibrium at vapor-liquid interface. General frame of previous rigorous model[1] is retained but tailored for flash equilibrium calculation of vapor-liquid interfacial thermodynamics. The model is based on complete time-dependent conservation equations with a full account of variable properties and vapor-liquid interfacial thermodynamics. The influences of high-pressure phenomena, including ambient gas solubility, thermodynamic non-ideality, and property variation on the droplet evaporation are investigated. The governing equations and associated moving interfacial boundary conditions are solved numerically using a implicit scheme with the preconditioning method and the dual time integration technique. And a parametric study of entire droplet vaporization history as a function of ambient pressure, temperature has been conducted. Some computational results are compared with Sato's experimental data for the validation of calculations. For low ambient temperatures, the droplet lifetime first increases with pressures, then decreases for high pressures. For higher ambient temperatures, the droplet lifetime increase with less amplitude than that of low ambient temperatures, which then decreases with more amplitude than that of low temperatures. The solubility of nitrogen can not be neglected in the high pressure and it becomes higher as the pressure goes up.

• Journal of the Korean Chemical Society
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• v.11 no.4
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• pp.143-149
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• 1967

The Transient State Theory of Significant Liquid Structure is applied to a binary liquid solution of benzene and carbon tetrachloride, which gives slightly positive deviation from Raoults law. The partition function for the solution is derived according to the proposed theory. The various thermodynamic properties such as total and partial vapor pressures, molar volumes, entropies of mixing, and compressibilities are calculated at three different temperatures, 298.15^{\circ}K$, 313.15^{\circ}K$ and 343.1515^{\circ}K$. The calculated values agree satisfactorily with experimental data.

• Korean Journal of Materials Research
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• v.23 no.10
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• pp.555-561
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• 2013

The hardenability of low-carbon boron steels with different molybdenum and chromium contents was investigated using dilatometry, microstructural observations and secondary ion mass spectroscopy (SIMS), and then discussed in terms of the segregation and precipitation behaviors of boron. The hardenability was quantitatively evaluated by a critical cooling rate obtained from the hardness distribution plotted as a function of cooling rate. It was found that the molybdenum addition was more effective than the chromium addition to increase the hardenability of boron steels, in contrast to boron-free steels. The addition of 0.2 wt.% molybdenum completely suppressed the formation of eutectoid ferrite, even at the slow cooling rate of $0.2^{\circ}C/s$, while the addition of 0.5 wt.% chromium did this at cooling rates above $3^{\circ}C/s$. The SIMS analysis results to observe the boron distribution at the austenite grain boundaries confirmed that the addition of 0.2 wt.% molybdenum effectively increased the hardenability of boron steels, as the boron atoms were significantly segregated to the austenite grain boundaries without the precipitation of borocarbide, thus retarding the austenite-to-ferrite transformation compared to the addition of 0.5 wt.% chromium. On the other hand, the synergistic effect of molybdenum and boron on the hardenability of boron steels could be explained from thermodynamic and kinetic perspectives.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.896-901
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• 1995

The critical micelle concentrations(CMC$^*$) of the mixed surfactant systems of Sodium dodecyl sulfate(SDS) with Tetraethylene glycol monododecyl ether(TGME) in the aqueous solutions of NaCl at $25^{\circ}C$ were determined as a function of the overall mole fraction of $SDS(\alpha1)$ by the use of surface tension method. Various thermodynamic parameters for the micellization of SDS/TGME mixed surfactant systems were calculated and analyzed by means of the equations derived from the nonideal mixed micelle model, based on the pseudo-phase separation model.