• Current Optics and Photonics
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• v.8 no.2
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• pp.138-150
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• 2024

This study is essential for advancing our knowledge about the interaction between long-range high-power lasers and energetic materials, with a particular emphasis on understanding the response of a 155-mm shell under various surface irradiations, taking into account external factors such as atmospheric disturbances. The analysis addresses known limitations in understanding the use of non-realistic targets and the negligence of ambient conditions. The model employs the three-dimensional level-set method, computer-aided design (CAD)-based target design, and a message-passing interface (MPI) parallelization scheme that enables rapid calculations of the complex chemical reactions of the irradiated high explosives. Important outcomes from interaction modeling include the accurate prediction of the initiation time of ignition, transient pressure, and temperature responses with the location of the initial hot spot within the shell, and the relative magnitude of noise with and without the presence of physical ambient disturbances. The initiation time of combustion was increased by approximately a factor of two with atmospheric disturbance considered, while slower heating of the target resulted in an average temperature rise of approximately 650 K and average pressure increase of approximately 1 GPa compared to the no ambient disturbance condition. The results provide an understanding of the interaction between the high-power laser and energetic target at a long distance in an atmospheric condition.

• Journal of the Korean Chemical Society
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• v.46 no.6
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• pp.495-501
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• 2002

The critical micelle concentration(CMC) and the counterion binding constant(B) for the mixed micel-lization of sodium n-octanoate(SOC) with n-octylammonium chloride(OAC) were determined as a function of the overall mole fraction of $SOC({\alpha}_1).$ Various thermodynamic parameters($x_i$, $Y_i$, $C_i$, $${\alpha}_i^M$$, and $\Delta$$H_{mix}$) for the mixed micellization of the SOC/OAC systems have been calculated and analyzed by means of the equations derived from the nonideal mixed micellar model. The results show that there are great deviations from the ideal behavior for the mixed micellization of these systems. And other thermodynamic parameters(${\Delta}$$G^0_m$, ${\Delta}$$H^0_m$, and ${\Delta}$$S^0_m$) associated with the micellization of SOC,OAC, and their $mixture({\alpha}_1=0.5)$ have been also estimated from the temperature dependence of CMC and B values, and the significance of these parameters and their relation to the theory of the micelle formation have been considered and analyzed by comparing each other.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.623-629
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• 2011

The adsorption characteristics of tricyclazole by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of tricyclazole were carried out at 298, 308 and 318 K, using aqueous solutions with 250, 500 and 1,000 mg/L initial concentration of tricyclazole. It was established that the adsorption equilibrium of tricyclazole on granular activated carbon was successfully fitted by Freundlich 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 250, 500 and 1,000 mg/L initial concentration of tricyclazole, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The positive value for enthalpy, -66.43 kJ/mol indicated that adsorption interaction of tricyclazole on activated carbon was an exothermic process. The estimated values for standard free energy were -5.08~-8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a exothermic process.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.430-436
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• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.807-815
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• 2017

This study investigated the removal efficiency of residual pentane from paclitaxel according to the drying temperature in the case of rotary evaporation, and performed a kinetic and thermodynamic analysis of the drying process. At all the temperatures (25, 30, 35, 40, and $45^{\circ}C$), a large amount of the residual solvent was initially removed during the drying, and the drying efficiency increased when increasing the drying temperature. Five drying models (Newton, Page, modified Page, Henderson and Pabis, Geometric) were then used for the kinetic analysis, where the Henderson and Pabis model showed the highest coefficient of determination ($r^2$) and lowest root mean square deviation (RMSD), indicating that these models were the most suitable. Furthermore, in the thermodynamic analysis of the rotary evaporation, the activation energy ($E_a$) was 4.9815 kJ/mol and the standard Gibbs free energy change (${\Delta}G^0$) was negative, whereas the standard enthalpy change (${\Delta}H^0$) and standard entropy change (${\Delta}S^0$) were both positive, indicating that the drying process was spontaneous, endothermic, and irreversible.

• Clean Technology
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• v.23 no.2
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• pp.188-195
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• 2017

This research studied the adsorption of basic dye, Basic Blue 3 (BB3) by using coal-based granular activated carbon (C-GAC) from aqueous solution. All experiments were performed in batch processes, and adsorption parameters such as C-GAC dosage, contact time, initial dye concentration and temperature were evaluated. The removal efficiency of BB3 was increased with increasing the C-GAC dosage and 100% of initial concentration, $50mg\;L^{-1}$ was removed above 0.2 g of C-GAC. Also, the time to reach equilibrium depended on the initial dye concentration. According to the Langmuir model, the maximum uptakes of C-GAC were calculated to be 66.45, 84.97 and $87.19mg\;g^{-1}$ at 25, 35 and $45^{\circ}C$, respectively. In addition, thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were investigated.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.220-225
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• 2013

The adsorption characteristics of phenol by the powdered activated carbon (PAC) were investigated by series of batch experiments. The pseudo-second-order model described the adsorption kinetics adequately with correlation coefficients over 0.999, indicating chemical adsorption as the rate-limiting step. The kinetic rate constants were from 0.55 to 19.81 mg $mg^{-1}min^{-1}$. The adsorption isotherm followed the Langmuir isotherm, indicating the homogeneous mono-layer adsorption onto the surface of the adsorbent. The values of activation energy, enthalpy and entropy were 17.44 kJ $mol^{-1}$, -8.26 kJ $mol^{-1}$ and -18.94 J $mol^{-1}K^{-1}$, respectively. The Gibbs free energy was in the range of -2.89~-2.14 kJ $mol^{-1}$. The results show that the phenol adsorption is physical, spontaneous and exothermic reaction.

• Clean Technology
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• v.30 no.3
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• pp.228-238
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• 2024

Electrolytes are one of the essential components of a lithium-ion battery. They determine the battery's lifespan and cell characteristics. The dielectric constant is a key thermophysical property for determining how much salt can be dissociated and solvated in a solution. Hence, fast and reliable dielectric constant measurement is essential when formulating an electrolyte solution. This work implemented an open-ended coaxial probe (OECP) station as a quick and reliable tool to measure the complex permittivity spectra of electrolyte solutions. The capability of the OECP station was tested by measuring the complex permittivity of propylene carbonate (PC), dimethyl carbonate (DMC), and their mixtures from 0.1 to 8 GHz at 288.15, 298.15, and 308.15 K. The obtained dielectric spectra were then interpreted based on dielectric relaxation models and thermodynamic theories. The measured static dielectric constant data agreed well with the data from previous studies. They were also correlated using the Wang-Anderko thermodynamic model, showing approximately a 1% deviation from the experimental data. In addition, the relaxation characteristics, including the relaxation time and the Cole-Davidson exponent, showed that the microstructure of the solution significantly changes at the propylene carbonate mole fraction of 0.4. These results and methodologies are expected to contribute to the further understanding of electrolyte solutions and ultimately lead to the optimization of electrolyte formulation for lithium-ion batteries.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.723-730
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• 2017

The batch experiments by response surface methodology (RSM) have been applied to investigate the influences of operating parameters such as temperature, initial concentration, contact time and adsorbent dosage on 2,4-dichlorophenol (2,4-DCP) adsorption with an activated carbon prepared from waste citrus peel (WCAC). Regression equation formulated for the 2,4-DCP adsorption was represented as a function of response variables. Adequacy of the model was tested by the correlation between experimental and predicted values of the response. A fairly high value of $R^2$ (0.9921) indicated that most of the data variation was explained by the regression model. The significance of independent variables and their interactions were tested by the analysis of variance (ANOVA) and t-test statistics. These results showed that the model used to fit response variables was significant and adequate to represent the relationship between the response and the independent variables. The kinetics and isotherm experiment data can be well described with the pseudo-second order model and the Langmuir isotherm model, respectively. The maximum adsorption capacity of 2,4-DCP on WCAC calculated from the Langmuir isotherm model was 345.49 mg/g. The rate controlling mechanism study revealed that film diffusion and intraparticle diffusion were simultaneously occurring during the adsorption process. The thermodynamic parameters indicated that the adsorption reaction of 2,4-DCP on WCAC was an endothermic and spontaneous process.

• Ocean Science Journal
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• v.43 no.4
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• pp.195-208
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• 2008

This paper evaluates whether a thermodynamic ocean-carbon model can be used to predict the monthly mean global fields of the surface-water partial pressure of $CO_2$ ($pCO_{2SEA}$) from sea surface salinity (SSS), temperature (SST), and/or nitrate ($NO_3$) concentration using previously published regional total inorganic carbon ($C_T$) and total alkalinity ($A_T$) algorithms. The obtained $pCO_{2SEA}$ values and their amplitudes of seasonal variability are in good agreement with multi-year observations undertaken at the sites of the Bermuda Atlantic Timeseries Study (BATS) ($31^{\circ}50'N$, $60^{\circ}10'W$) and the Hawaiian Ocean Time-series (HOT) ($22^{\circ}45'N$, $158^{\circ}00'W$). By contrast, the empirical models predicted $C_T$ less accurately at the Kyodo western North Pacific Ocean Time-series (KNOT) site ($44^{\circ}N$, $155^{\circ}E$) than at the BATS and HOT sites, resulting in greater uncertainties in $pCO_{2SEA}$ predictions. Our analysis indicates that the previously published empirical $C_T$ and $A_T$ models provide reasonable predictions of seasonal variations in surface-water $pCO_{2SEA}$ within the (sub) tropical oceans based on changes in SSS and SST; however, in high-latitude oceans where ocean biology affects $C_T$ to a significant degree, improved $C_T$ algorithms are required to capture the full biological effect on $C_T$ with greater accuracy and in turn improve the accuracy of predictions of $pCO_{2SEA}$.