• Resources Recycling
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• v.17 no.2
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• pp.63-69
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• 2008

The adsorption features of $Ni^{2+}$ onto spent alkaline manganese batteries powder have been investigated with the adsorbent dose, initial concentration of adsorbate and temperature as the experimental variables. The adsorption reaction of $Ni^{2+}$ ion followed the pseudo-second order rate model, and the adsorption rate constants($k_2$) decreased with increasing initial concentration of nickel ion. The equilibrium adsorption data were fitted to the Langmuir and Freundlich models. The Freundlich model represents the equilibrium data better than the Langmuir model in this initial adsorbate concentration range. As the temperature increased, the adsorbed amount of nickel ion at equilibrium was also increased, which indicated that the adsorption reaction was endothermic. Based on the experimental results obtained along with temperatures, thermodynamic parameters such as ${\Delta}H^{\circ},\;{\Delta}G^{\circ},\;and\;{\Delta}S^{\circ}$ were calculated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.224-234
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• 1997

In order to make high purity materials including low contents of interstitial impurities, 70 ㎾ electron beam melter was manufactured. The sponge Ti and Ti-6Al-4V alloy were required and melted by electron beam melter. Based on the experimental results of sponge Ti refining by electron beam melting, the purity of Ti was increased for 180 seconds but thereafter did not significantly vary. In addition, it was found that with number of melting, the purity of Ti did and vary but the yield of Ti was decreased. As a results of Ti refining, high purity Ti of 3N (99.9 wt%) could be obtained including interstitial impurities with total contents of which were maximum 900 ppm. From the experimental results of Ti-6Al-4V alloy electron beam melting, the amounts of Al loss could be estimated through thermodynamic data calculated from the regular solution model and the model of solute removal kinetics and the alloy composition calculated from the models was in accord with the experimental composition of the alloy, It took 10 minutes to make Ti-29Al-4V alloy calculated from the model into Ti-6Al-4V alloy and the composition of Ti-6Al-4V alloy was very homogeneous.

• Clean Technology
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• v.17 no.2
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• pp.97-102
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• 2011

The adsorption characteristics of amatanth dye by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of amaranth dye were carried out at 298, 308 and 318 K, using aqueous solutions with 100, 200 and 300 mg/L initial concentration of amatanth. It was established that the adsorption equilibrium of amaranth dye on granular activated carbon was successfully fitted by Langmuir isotherm equation at 298 K. The pseudo first order and pseudo second order models were used to evaluate the kinetic data and the pseudo second order kinetic model was the best with good correlation. Values of the rate constant ($k_2$) have been calculated as 0.1076, 0.0531, and 0.0309 g/mg h at 100, 200 and 300 mg/L initial concentration of amatanth, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The estimated values for standard free energy were -5.08 - -8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a spontaneous process. The positive value for enthalpy, 38.89 kJ/mol indicates that adsorption interaction of amatanth dye on activated carbon is an endothermic process.

• Computational Structural Engineering
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• v.9 no.1
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• pp.65-76
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• 1996

The initiation and growth of microcracks or microvoids inside concrete results in the progressive degradation of concrete. This damage processing along processing along with plastic deformation is main cause of nonlinear behavior of concrete. In this study, a continuum damage model of concrete is developed for the analysis of the nonlinear behavior of concrete due to damage and elasto-plastic deformation. Anisotropic damage tensor is used to describe the anisotropy of concrete and hypothesis of equivalent elastic energy is used to define the effective elastic tensor. The damage model including the damage evolution law and constitutive equation is derived with damage variable and damage surface which is defined by damage energy release rate by using the Helmholtz free energy and dissipation potential based on the thermodynamic principles. By adopting a typical plasticity model of concrete, plasticity of concrete is included to this model. Afinite element analysis program implemented with this model was developed and finite element analysis was performed for the analyses of concrete subjected to uniaxial and biaxial loadings. Comparison of the results of analysis with those of experiments and other models shows that the model successfully predicts the nonlinear behavior of concrete.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.64-70
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• 2015

Batch experiment studies were carried out for adsorption of congo red using granular activated carbon with various parameters such as activated carbon dose, pH, initial dye concentration, temperature and contact time. Equilibrium experimental data are fitted to the Langmuir, Freundlich, Temkin and Dubin-Radushkevich isotherm equations. From Freundlich's separation factor (1/n) estimated, adsorption could be employed as effective treatment method for adsorption of congo red from aqueous solution. Base on Temkin constant (B) and Dubinin-Radushkevich constant (E), this adsorption process is physical adsorption. Adsorption kinetics has been tested using pseudo-first order and pseudo second order models. The results followed pseudo second order model with good correlation. Adsorption process of congo red on granular activated carbon was endothermic (${\Delta}H$=42.036 kJ/mol) and was accompanied by decrease in Gibbs free energy (${\Delta}G$=-2.414 to -4.596 kJ/mol) with increasing adsorption temperature.

• Nuclear Engineering and Technology
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• v.28 no.2
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• pp.103-117
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• 1996

A mathematical model of vapor explosion propagation is presented. The model predict two-dimensional, transient flow fields and energies of the four fluid phases of melt drop, fragmented debris, liquid coolant and vapor coolant by solving a set of governing equations with the relevant constitutive relations. These relations include melt fragmentation, coolant-phase-change, and heat and momentum exchange models. To allow thermodynamic non-equilibrium between the coolant liquid and vapor, an equation of state for oater is uniquely formulated. A multiphase code, TRACER, has been developed based on this mathematical formulation. A set of base calculations for tin/water explosions show that the model predicts the explosion propagation speed and peak pressure in a reasonable degree although the quantitative agreement relies strongly on the parameters in the constitutive relations. A set of calculations for sensitivity studies on these parameters have identified the important initial conditions and relations. These are melt fragmentation rate, momentum exchange function, heat transfer function and coolant phase change model as well as local vapor fractions and fuel fractions.

• Journal of The Korean Astronomical Society
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• v.43 no.5
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• pp.161-168
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• 2010

Magnetars are neutron stars possessing a magnetic field of about $10^{14}-10^{15}$ G at the surface. Thermodynamic properties of neutron star matter, approximated by pure neutron matter, are considered at finite temperature in strong magnetic fields up to $10^{18}$ G which could be relevant for the inner regions of magnetars. In the model with the Skyrme effective interaction, it is shown that a thermodynamically stable branch of solutions for the spin polarization parameter corresponds to the case when the majority of neutron spins are oriented opposite to the direction of the magnetic field (i.e. negative spin polarization). Moreover, starting from some threshold density, the self-consistent equations have also two other branches of solutions, corresponding to positive spin polarization. The influence of finite temperatures on spin polarization remains moderate in the Skyrme model up to temperatures relevant for protoneutron stars. In particular, the scenario with the metastable state characterized by positive spin polarization, considered at zero temperature in Phys. Rev. C 80, 065801 (2009), is preserved at finite temperatures as well. It is shown that, above certain density, the entropy for various branches of spin polarization in neutron matter with the Skyrme interaction in a strong magnetic field shows the unusual behavior, being larger than that of the nonpolarized state. By providing the corresponding low-temperature analysis, we prove that this unexpected behavior should be related to the dependence of the entropy of a spin polarized state on the effective masses of neutrons with spin up and spin down, and to a certain constraint on them which is violated in the respective density range.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.134-147
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• 2001

Laser cladding process accompanies phase transformations from melting (on heating) through solidifying (on cooling) at the same time within a small material volume and to final solid phase. The phase transformations are not reversible, but an irreversible thermodynamic process; they accompany either absorption or release of thermal energy (referred to latent heat) during transformation. Yet, most analyses on materials processed by laser as a heat source have been performed on models of neglecting the latent heat in the process and those did not Justify the simplification. With literatures on the laser material process, we have not place an answer to how little the assumption affects on analyses. This led us to our current study: the effects of latent heat on thermo-mechanical analysis. To this end, we developed a fairly accurate program accommodating an algorithm for enforcing the latent heat whenever necessary and ran it combining with ABAQUS$^{TM}$. The simulation techniques we used in this study were verified by directly comparing our prediction with experimental publications elsewhere; our numerical results agreed accurately with the experiments. On the effects of the latent heat, we performed two alternatives about considering the latent heat in analysis, and compared each other. As a result, we found that more accurate conclusions might come out when considering the latent heat in process analyses.s.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.1
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• pp.63-73
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• 2010

A comprehensive mapping project for agroclimatic zoning in South Korea will end by April 2010, which has required 4 years, a billion won (ca. 0.9 million US dollars) and 22 experts from 7 institutions to complete it. The map database from this project may be categorized into primary, secondary and analytical products. The primary products are called "high definition" digital climate maps (HD-DCMs) and available through the state of the art techniques in geospatial climatology. For example, daily minimum temperature surfaces were prepared by combining the climatic normals (1971-2000 and 1981-2008) of synoptic observations with the simulated thermodynamic nature of cold air by using the raster GIS and microwave temperature profiling which can quantify effects of cold air drainage on local temperature. The spatial resolution of the gridded climate data is 30m for temperature and solar irradiance, and 270m for precipitation. The secondary products are climatic indices produced by statistical analysis of the primary products and includes extremes, sums, and probabilities of climatic events relevant to farming activities at a given grid cell. The analytical products were prepared by driving agronomic models with the HD-DCMs and dates of full bloom, the risk of freezing damage, and the fruit quality are among the examples. Because the spatial resolution of local climate information for agronomic practices exceeds the current weather service scale, HD-DCMs and the value-added products are expected to supplement the insufficient spatial resolution of official climatology. In this lecture, state of the art techniques embedded in the products, how to combine the techniques with the existing geospatial information, and agroclimatic zoning for major crops and fruits in South Korea will be provided.

• Analytical Science and Technology
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• v.7 no.4
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• pp.505-515
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• 1994

$^1H$ NMR spectra for monocyanide ligated ferriprotoporphyrin(hemin) complex and dicyanide coordinated hemin complex in dimethylsulfoxide(DMSO-$d_6$) solution have been recorded and analyzed. NMR spectra of hemin-cyanide complexation in DMSO-$d_6$ exhibit that the cyanide ligation to hemin is temperature-dependent. Thermodynamic parameters for the monocyanide ligated hemin to dicyanide ligated hemin are consistent with endothermic process with ${\Delta}H^{\circ}=736.6cal/mol$ and ${\Delta}S^{\circ}=16.4eu$. Detailed analysis of the anomalous deviation from Curie behavior for CN/DMSO coordinated hemin complex demonstrates the presence of a high spin character, and this weaker axial field relative to the purely low-spin dicyanide hemin complex is supposed to attribute to instantaneously ruptured iron-DMSO bond. This complex may serve as a useful model to characterize electronic/molecular structure of hemoproteins, which one of axial ligands is weak.