• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.427-438
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• 2023

Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acid-base titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.55-60
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• 2015

Recent engine development has focused mainly on the improvement of engine efficiency and output emissions. The improvements in efficiency are being made by friction reduction, combustion improvement and thermodynamic cycle modification. Computer simulation has been developed to predict the performance of a spark ignition engine. The effects of various cylinder pressure, heat release, flame temperature, unburned gas temperature, flame properties, laminar burning velocity, turbulence burning velocity, etc. were simulated. The simulation and analysis show several meaningful results. The objective of the present study is to develop a combustion model for a spark ignition engine running with isooctane as a fuel and predicting its behavior.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.377-385
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• 2015

This paper presents a thermodynamic performance analysis of regenerative organic Rankine cycle (ORC) using turbine bleeding to utilize low-grade finite thermal energy. Refrigerant R245fa was selected as the working fluid. Special attention is paid to the effects of the turbine bleeding pressure and the turbine bleed fraction on the thermodynamic performance of the system such as net power production and thermal efficiency. Results show that the thermal efficiency has an optimum value with respect to the turbine bleeding pressure and the net power production is lower than the basic ORC while the thermal efficiency is higher.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1238-1247
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• 2003

Simplified thermodynamic analysis of high pressure 4-stage reciprocating compressors with 4 inter-coolers has been investigated to predict a behavior of a compressor system for NGV(natural gas vehicles). A computer program has been developed to predict and estimate the performance of high pressure 4-stage reciprocating compressor system. Thermodynamic properties of compressed natural gas(CNG) were calculated by ideal gas theory and compression cycle was assumed as reversible adiabatic compression and expansion processes, and isobaric intake and discharge processes. Comparison between results predicted by calculation model and measured by experimental tests is presented.

• Journal of the Korean Solar Energy Society
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• v.23 no.4
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• pp.45-54
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• 2003

For cooling of double effect absorption heat pump system of solar heating source, analysis of thermodynamic design data has been done to find the property of Libr-water + ethylene Glycol mixture for working fluid by computer simulation. Derived thermodynamic design data, enthalpy based coefficient of performance and flow ratio for possible combinations of operating temperature for water - LiBr and Ethylene Glycol mixture ($H_2O$ : CHO ratio 10:1 by mole) by computer simulation are done. The obtained results, COP and mass flow ratio of the water - lithium bromide - ethylene glycol system, are compared with data for the water-Libr pair solution.

• Journal of the Korean Solar Energy Society
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• v.22 no.4
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• pp.51-61
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• 2002

Analysis of thermodynamic design data of double effect solar absorption heat pump system for heating has been done to find the property of Libr-water + ethylene Glycol mixture for working fluid by computer simulation. Derived thermodynamic design data. enthalpy based coefficient of performance and flow ratio for possible combinations of operating temperature for water - LiBr and Ethylene Glycol mixture (H2O: CHO ratio 10:1 by mole) by computer simulation. The obtained results, COP and mass flow ratio of the water-lithium bromide-ethylene glycol system, are compared with data for the water-Libr pair solution.

• Solar Energy
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• v.9 no.3
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• pp.73-80
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• 1989

This paper presents as assessment based on steady-state thermodynamic analysis and computer modeling of a double effect generation absorption heating cycle for solar air-conditioning to find operating temperature ranges. The influences of component temperatures on the heating coefficients of performance and mass flow ratio have been investigated to obtain optimum operating conditions for the proposed air conditioning system. And the single and double effect absorption cycles are compared with each other over the same range of temperatures.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.225-228
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• 2012

Thermodynamic and economic analysis on various type of gas turbine combined cycle power plants was presented to build up the criteria for optimization of power plants. The efficiency considered about energy level difference between electricity and heat was introduced. The efficiency on power and heat generation of power plants whose have different purpose was estimated and power generation costs on various type of combined heat and power plants : fired/unfired, condensing/non-condensing mode, single/double pressure HRSG.

• Journal of the Korean institute of surface engineering
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• v.23 no.1
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• pp.27-33
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• 1990

Thermodynamic analysis on silicon consumpton during the chemical vapor deposition of tungten was carried out by calculation equilibrium concerations of all possible product species utilizing a computer progrom according to VCS.(Villars-Cruise-Smith) algorithm. The calculation could show various reaction paths which dominate the tungsten deposition under different process conditions. According to the calculation, the consumption of silicon can also be reduced at a lower total pressure SiH4 without H2 as the reacting gas is most effective for suppression of the excessive consumption of silicon during the deposition process.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.237-249
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• 2014

Deposition of amyloid-${\beta}$ ($A{\beta}$) proteins is the conventional pathological hallmark of Alzheimer's disease (AD). The $A{\beta}$ protein formed from the amyloid precursor protein is predominated by the 40 residue protein ($A{\beta}40$) and by the 42 residue protein ($A{\beta}42$). While $A{\beta}40$ and $A{\beta}42$ differ in only two amino acid residues at the C-terminal end, $A{\beta}42$ is much more prone to aggregate and exhibits more neurotoxicity than $A{\beta}40$. Here, we investigate the molecular origin of the difference in the aggregation propensity of these two proteins by performing fully atomistic, explicit-water molecular dynamics simulations. Then, it is followed by the solvation thermodynamic analysis based on the integral-equation theory of liquids. We find that $A{\beta}42$ displays higher tendency to adopt ${\beta}$-sheet conformations than $A{\beta}40$, which would consequently facilitate the conversion to the ${\beta}$-sheet rich fibril structure. Furthermore, the solvation thermodynamic analysis on the simulated protein conformations indicates that $A{\beta}42$ is more hydrophobic than $A{\beta}40$, implying that the surrounding water imparts a larger thermodynamic driving force for the self-assembly of $A{\beta}42$. Taken together, our results provide structural and thermodynamic grounds on why $A{\beta}42$ is more aggregation-prone than $A{\beta}40$ in aqueous environments.