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”.

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”.

Optimization of tool path and cutting condition is very important in different kinds of machining for reducing machining time and improving machining accuracy

In general, a machining centre has an ability to provide sufficient manufacturing precision and efficiency with high adaptability for various types of machining features, but it does not have a function of selecting the optimum tool path for the achieved cutting speed.

Many studies have been conducted for the optimization of tool path in different kinds of machining. Special attention was paid to drilling, one of the most widely used metal machining, and many experimental and mechanical approaches were presented for modelling cutting force based on drill geometry and cutting conditions.

Kim Myong Il, a section head at the Faculty of Mechanical Science and Technology, has proposed an optimization method for drilling the hole clusters in a machining center (MC) on the basis of a cutting force model, in which the tool path is optimized to reduce machining time and power consumption, and cutting condition is optimized to improve machining accuracy. He obtained a predictive model of cutting force from drilling tests using multigene genetic programming (MGGP).

He applied the proposed method to MC for machining trolleybus underframes so that it could provide high machining accuracy and long tool life as well as shorter machining time and low power consumption.

You can find the details in his paper “Optimization of Tool Path and Cutting Condition based on Model of Drilling Force in the Machining Center” in “Proceedings of KUTIC-2025”.