Jo Apr 20, 2026
Soda ash, one of the most important basic chemical raw materials, is widely used in chemicals, detergent and soap, petrochemical, pulp and paper, glass, metal, ceramic and food industries. Soda ash is mainly produced from natural trona and other sodium carbonate-containing minerals, in addition to the ammonia-soda and ammonium sulfate-soda methods. In the production of soda ash based on mirabilite, the ammonium sulfate-soda method is considered the most suitable one because of its high utilization degree of mirabilite, low energy consumption, and production of ammonium sulfate as a byproduct.
The depletion of nonrenewable energy resources and the high cost associated with it have made energy conservation and more efficient use of energy an urgent matter. Consequently, it is important to find a way of reducing energy consumption in the production of soda ash.
The solution is exergy analysis, which helps understand the energy distribution, detect the location of energy consumption and provide a direction for energy saving of a system.
The difficulty in exergy analysis of electrolyte systems is to accurately estimate the chemical exergy of substances or species involved in aqueous electrolyte solution. Furthermore, as for the soda ash production process by the ammonium sulfate-soda method, the gas-liquid reaction and salt precipitation reaction occur simultaneously in the Na2SO4-NH3-CO2-H2O electrolyte system, so exergy analysis cannot be carried out using the chemical exergy of elements and substances presented by preceding researchers.
Pak Kyong Song, a researcher at the Faculty of Chemical Engineering, has proposed a novel approach to calculate the chemical exergy of an aqueous electrolyte system accompanied by gas-liquid reaction and salt precipitation reaction, based on the Pitzer equation.
He simulated a soda ash production process using Aspen Plus and performed an exergy analysis based on the thermodynamic data obtained from the simulation.
The result showed that the exergy destruction of the entire process is 99.945kW and exergy efficiency is 59.57%. In addition, he found that the units with low exergy efficiency in the process are condenser and absorption towers such as NH3 absorption tower, carbonation tower and water washing tower, which are the primary targets of energy saving.
For more details, you can refer to his paper “Study on Exergy Analysis of the Soda Ash Production Process by the Ammonium Sulfate-Soda Method” in “ACS Omega” (SCI).
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Jo Apr 19, 2026
In general, FGM structures are subjected to various external excitations such as earthquakes, winds, thermal load and jet noise in their operation. Therefore, studying the dynamic behavior of composite structures under different types of external load is considered an important task.
Kim Jin Mi, a student at the Faculty of Mechanical Science and Technology, analyzed the free vibration and stationary stochastic response of functionally graded (FG) rectangular plates with varying thickness in supersonic flow and thermal environment.
She investigated two types of material property variations of FG plates with varying thickness: variations along the direction perpendicular to the mid-surface and the bottom surface.
Considering the effects of aerodynamic pressure and thermal load, she derived governing equations of motion of FG plates with varying thickness using Hamilton’s principle within the framework of first-order shear deformation theory. Then, she constructed a meshfree Jacobi radial point interpolation (Jacobi-RPI) shape function by combining the Jacobi polynomials and radial basis to approximate the displacement components of the plate.
She confirmed the accuracy and reliability of the proposed approach through sufficient comparisons with numerical results from the published literature and the finite element software ABAQUS.
For more information, please refer to her paper “Meshfree Dynamic Analysis of Functionally Graded Rectangular Plates with Varying Thickness in Supersonic Flow and Thermal Environment” in “Acta Mechanica Solida Sinica” (SCI).
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Jo Apr 17, 2026
Functionally graded material (FGM) shells and plates, which eliminate interface problems and stress concentrations of composite laminated structures, are regarded as main structures for mechanical engineering, civil engineering, marine, automotive and many other applications. Recently, many scholars have paid their attention to numerical and experimental studies for mechanical behavior of various structures made of functionally graded materials.
Various methods such as Haar wavelet method, Jacobi–Ritz method, spectral-Tchebychev method, dynamic stiffness method, finite element method and meshfree method have been employed for the numerical analysis of composite structures. In recent years, the meshfree method that needs no meshes for discretization of problem domains has attracted significant attention of many scholars.
Kwak Song Hun, a researcher at the Faculty of Mechanical Science and Technology, has proposed a meshfree Jacobi-radial point interpolation (Jacobi-RPI) method for free vibration and stochastic response analyses of functionally graded eccentric sectorial and annular plates.
He adopted the Hamilton’s principle to establish motion equations of functionally graded material (FGM) eccentric sectorial plates in the framework of first order shear deformation theory (FSDT). He transformed the eccentric sectorial plate into a simple square domain by using the coordinate mapping technique, and approximated the displacement components of the sectorial plate by using the meshfree Jacobi-RPI shape function. He obtained motion equations of FGM eccentric annular plates by coupling the equations of several sectorial plates.
He has validated the accuracy and reliability of the proposed method through a sufficient number of numerical studies for the free vibration and dynamic response analysis of eccentric sectorial and annular plates.
For more information, please refer to his paper “A meshfree approach for free vibration and stationary stochastic response analyses of functionally graded eccentric sectorial and annular plates” in “Journal of the Brazilian Society of Mechanical Sciences and Engineering” (SCI).
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Jo Apr 16, 2026
The mixed refrigerant is a mixture of several simple refrigerants in a certain proportion. In refrigeration cycles, the mixed refrigerant is generally less energy-consuming compared to its pure components. In addition, the ozone layer destruction coefficient (ODP) and the global warming coefficient (GWP) are low.
Typical mixed refrigerants include R12/R13, R22/R13, R22/R23, R134a/R23, R22/R14, R22/R23/R14, R134a/R23/R14, R600a/R23/R14, R600a/R23/R50, etc.
R600a has zero ODP and GWP, no poisoning, high latent heat of vaporization and high refrigeration efficiency. R508B is an azeotropic mixture consisting of R23 and R116, an environmentally friendly refrigerant with ODP of 0. In automatic cascade refrigeration systems, the composition ratio of mixture has a great influence on the system performance.
Ri Ju Hyok, a researcher at the Faculty of Thermal Engineering, constructed an automatic cascade refrigeration system using mixed refrigerant R600a/R508B, and analyzed its cycle characteristics, based on the thermal properties of the environmentally friendly mixed refrigerant R600a/R508B calculated by the Helmholtz energy mixture model. Then, by using Aspen Plus program, he analyzed the effect of various parameters on the cycle characteristics and optimized them.
Based on the optimization results, he built an experimental setup of an automatic cascade refrigeration system and carried out some performance experiments to confirm that the cycle characteristics analysis was relatively accurate.
You can find more information in his paper “Auto Cascade Refrigeration Process for Environmental Protection using Mixed Refrigerant R600a/R508B” in “Proceedings of KUTIC-2025”.
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Jo Apr 15, 2026
Selecting a suitable mining method in consideration of surface subsidence caused by underground mining, safety of stope and mining recovery rate under mining and geological conditions of a certain target is very important for safe mining, protection of surface structures and minimization of coal loss.
The results of previous studies show that better results can be obtained by analyzing the surface subsidence characteristics caused by the influence of mining operations using numerical simulation methods that can well reflect the nonlinear relationship between rock mass movement and deformation parameters.
Hong Kun Ui, dean of the Faculty of Mining Engineering, numerically investigated a suitable mining method in consideration of the surface subsidence and the safety of stope by using FLAC3D and SURPAC software with a change of stope pillar size in the case of mining thick coal seams with dip of 30° by using different room and pillar methods.
The numerical simulation results showed that when the interval between stope pillars is 4m, the maximum subsidence of surface is about 2.2cm, which ensures stope safety.
He introduced his method to Kaechon coal mine and proved its reliability.
For more details, you can refer to his paper “Numerical Simulation Analysis for the Selection of Suitable Mining Method in Consideration of the Surface Subsidence and the Safety of Stope and the Mining Recovery Rate” in “Proceedings of KUTIC-2025”.
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Jo Apr 14, 2026
Vanadium redox flow batteries (VRFBs) are large-scale electrochemical energy storage systems that enable the supply of stable and reliable power from wind or solar energy. Proton exchange membrane fuel cells (PEMFCs) are efficient and environmentally friendly electro-chemical energy conversion systems that produce only water and heat with clean hydrogen produced using renewable energy as fuel. On the other hand, EHC is an advanced electrochemical system that is indispensable for hydrogen energy cycle systems that purify and compress hydrogen simultaneously.
Sulfonated polyetheretherketone (SPEEK) membranes have been widely regarded as inexpensive proton exchange membranes for electrochemical energy systems such as VRFBs, PEMFCs and EHC due to their ease of fabrication, low cost, good proton conductivity, and excellent thermal and chemical stability.
General requirements for these applications are high proton conductivity, chemical and mechanical stability and impermeability of fuels and oxidants.
In order to improve the performance of membranes, Ju Il Myong, a researcher at the Faculty of Chemical Engineering, developed SPEEK/TiO2 nanopaper composite membranes with TiO2 nanopaper as a backbone and SPEEK polymer as a proton conducting medium, and evaluated their physicochemical properties.
Compared to pristine membranes, the SPEEK/TiO2 nanopaper composite membranes show nearly twice tensile strength, about 1/3 of vanadium permeability and low hydrogen gas permeability, and better performance and long lifetime in VRFB, PEMFC and EHC systems. The experimental results show that SPEEK/TiO2 nanopaper composite membranes can replace commercial Nafion® membranes in electrochemical energy systems.
If more information is needed, please refer to his paper “SPEEK/TiO2 Nanopaper Composite Membranes for Electrochemical Energy Systems” in “Proceedings of KUTIC-2025”.
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