Jo Jun 17, 2026
Spraying mist has been widely used in environmental purification, nanomaterial manufacturing and chemical industry to promote reactivity and improve cooling properties. Therefore, there have been many studies to improve the spray characteristics. To achieve various scientific and technological purposes such as environmental purification with a small amount of water and reagents, effective nanoparticle preparation using fine mist particles, rapid rise of reaction rate, and fogging with low energy consumption, researchers have investigated nozzle structures and spray methods for generating fine spray particles.
Generally, low pressure spraying is widely used rather than high pressure spraying because the latter has some shortcomings such as high energy consumption, severe wear of equipment, nozzle clogging in operation, etc. However, low pressure atomization is often used in conjunction with low pressure air jet because fine mist particles are difficult to obtain in large quantities.
The combined use of compressed air atomization can contribute to improving the efficiency in various processes including environmental purification, nanomaterial preparation, chemical reaction promotion, etc., due to its low energy consumption and high fogging efficiency.
Paek In Chol, vice dean of the Faculty of Mining Engineering, has investigated the spray characteristics and considered the optimum spraying conditions when low pressure air jet is combined with low-pressure water jet.
Using the Taylor Analogue Breaking (TAB) model, he simulated the droplet breaking up process and studied the time-dependent tearing behavior and the suitable pressure conditions.
The results show that most particles in the central part of the spraying zone are 0.8-12㎛ in diameter, and the spray pressure in the combined compressed air is the most suitable from 0.25 to 0.3MPa when the pressure of compressed air is set to be 0.2MPa.
You can find the details in his paper “Numerical Simulation of Water Spraying Characterization Improvement in Low Pressure” in “Proceedings of KUTIC-2025”.
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Jo Jun 16, 2026
The structure of a moisture separator reheater is very complex, and the cycle steam is heated during the film condensation of heating steam inside the tube bundle.
Previous works proposed a thermal calculation model and a calculation algorithm of a reheater tube bundle and linearized the quality variation of the heating steam and two-phase flow, but did not consider the subcooling of a condensate film.
Kim Myong Chol, a researcher at the Faculty of Thermal Engineering, has proposed an improved thermal calculation algorithm considering the nonlinearity of the steam quality inside the tube bundle and carried out a quantitative evaluation of the factors affecting heat transfer to provide a theoretical basis for determining the optimum design parameters of a moisture separator reheater.
He found out that measures must be taken to prevent U-tube bundles from sagging down in the design and manufacture of reheater bundles.
For more information, please refer to his paper “Analysis of Heat Transfer Characteristics of a Moisture Separator Reheater Considering the Variation of Steam Quality Inside the Tube” in “Proceedings of KUTIC-2025”.
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Jo Jun 15, 2026
Friction torque and load capacity of bearings are very important performance indicators. The high speed and precision of machines presupposes the minimization of the friction torque of bearings, and the long service life is guaranteed by the maximization of the dynamic load capacity. However, the friction torque and dynamic load capacity increase and decrease respectively with the changes of the internal geometric parameters of bearings, so a machine with long service life and good friction characteristics can be realized only by multi-objective optimization of the dynamic load capacity and friction torque of bearings.
Many researchers studied to maximize the dynamic load capacity of bearings and to minimize their friction torque, but there is a lack of confidence in the optimization results due to the lack of correlation, many simplified parts and lack of enough constraints
Ball bearings are most widely used because of their small friction torque and relatively simple manufacturing process. Ri Jong Hak, a researcher at the Faculty of Mechanical Science and Technology, fully presented the constraints that reflect the actual conditions of ball bearings and developed a new mathematical model to simultaneously optimize the dynamic load capacity and friction torque. On this basis, he optimized them using the genetic algorithm and verified its accuracy by the FEM.
The proposed method can be applied to the determination of internal geometric parameters to simultaneously optimize the dynamic load capacity and friction torque of ball bearings.
For more information, you can refer to his paper “A Novel Methodology for Determining the Internal Geometric Parameters of a Ball Bearing in Consideration of Load Capacity and Friction Torque” in “Proceedings of KUTIC-2025”.
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Jo Jun 14, 2026
Dimethyl carbonate (DMC) is one of the most important chemicals, which has a wide application range. It is used as the raw material of polycarbonate (PC) plastics, the solvent of electrolyte for energy storage devices, the additives of diesel fuel, etc. The worldwide carbonate synthesis industry is currently dominated by the transesterification method with ethylene oxide as a starting material, which was commercialized in the 1990s. However, the starting material, ethylene oxide, is from the crude oil and causes environmental pollution during production, so recently, the synthesis of carbonate based on urea has attracted attention.
At present, the achievement on the synthesis of DMC from urea and alcohol mainly comes from the research on catalysts and the most widely-used catalyst is ZnO. The reaction of DMC synthesis using ZnO as a catalyst proceeds according to the heterogeneous catalytic mechanism. However, to date, the ZnO catalyst used in previous studies is mostly prepared by the sol-gel method.
Preceding studies imply that 4-needle like nano-ZnO demonstrates stronger catalytic activity than spherical or sheet ZnO crystals, which improves reactions.
On the basis of the analysis, Kim Myong Hyok, a researcher at the Faculty of Chemical Engineering, studied the catalytic use of 4-needle like nano-ZnO prepared by the combustion method to improve the reaction time and temperature of dimethyl carbonate (DMC) synthesis, and the catalyst recovery, aiming to improve the DMC yield.
48g of methanol and 1g of catalyst were put into the reactor and heated to the desired reaction temperature, and then a liquid mixture of methanol 80g and urea 12g was added to the reactor for 10min. Ammonia generated during the reaction was removed three times through the safety valve of the reactor.
When nano-ZnO was used as a catalyst, the optimum reaction time and temperature of the DMC synthesis reaction were 3h and 140℃, respectively, with a DMC yield of 65.1%. The catalyst was recycled up to seven times.
You can find the details in his paper “Improvement in the Yield of Dimethyl Carbonate by 4-Needle like Nano-ZnO”in “Proceedings of KUTIC-2025”.
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Jo Jun 12, 2026
Dynamic chemical plating has been developed to overcome the disadvantages of conventional electroless plating (plating bath control, solution life limitation, difficult plating for large products, plating rate around 5㎛, etc.). Dynamic chemical plating can be employed for single metal plating such as copper, nickel and silver as well as alloy plating including Ni-P and Ni-B-P, and composite plating including Ni-B-P-graphene composite coating. Silver coating layers by the dynamic chemical plating are widely used for silver mirrors, electromagnetic shielding, and consumer goods production.
Ri Ju Chon, a researcher at the Faculty of Chemical Engineering, has experimentally studied the effect of silver concentration, ammonia water concentration, formaldehyde concentration, pH and temperature on the plating rate of dynamic chemical plating, and derived a relationship equation between each parameter and the rate by least squares approximation.
As the relative error between actual measured rate and calculated rate using the equation is less than 15%, the rate equation is considered useful for controlling plating process and clad thickness.
For further details, you can refer to his paper “Derivation of the Rate Equation of Silver Plating by Dynamic Chemical Plating” in “Proceedings of KUTIC-2025”.
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Jo Jun 11, 2026
Chlorination not only complicates the after-treatment process by dissolving some or most of the sulphides in the treatment of sulphide ores, but also increases the consumption of oxidizing agents such as chlorine gas. In addition, the stability of gold chloride complexes is not high, and when in contact with other reducing agents (sulphides in ores or products of low oxidation states produced during oxidative decomposition), it can be easily redeposited to significantly reduce leaching rate. Therefore, chlorination is relatively suitable for acidic ores with sulphur content less than 0.5%, and generally, pre-treatment and oxidative desulfurization are necessary for gold-bearing sulphides.
Kim Chang Sok, a researcher at the School of Science and Engineering, has proposed a new environmentally-friendly gold chlorination hydrometallurgy process consisting of pressure oxidation pretreatment, chloride leaching and ion exchange resin adsorption of high-sulfur refractory gold concentrate, identified necessary indices through basic research, and provided basic data for the application of environmentally-friendly non-cyanidation of refractory gold concentrate.
The highest gold leaching rate of about 96.54% was obtained when the pressure oxidized residue of refractory gold concentrate was chlorinated at pH=4, sodium hypochlorite concentration of 0.5%, sodium chloride concentration of 75g/L, temperature of 30℃, liquid-solid ratio of 3:1 and time of 120min.
For more information, you can refer to his paper “New Method of Environment-Friendly Chlorination Hydrometallurgy of Refractory Gold Concentrates” in “Proceedings of KUTIC-2025”.
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