Terbium belongs to the lanthanide or “rare earth elements (REE)” group of elements in the periodic table. However, rare earth elements are dispersed and they are not generally found concentrated as rare earth minerals (REM) in economically exploitable ore deposits. Terbium only occurs in trace quantities even in its ores. It is found in some minerals such as bastnaesite, monazite, xenotime, euxenite and gadolinite ores, but in low concentrations, on the order of 1%.

Terbium and its compounds are used as phosphors. Terbium phosphors give off a green light when struck by electrons. Phosphorescent terbium compounds are used in cathode ray tubes, light-emitting diodes, lasers, sensors, etc. Thus, terbium extraction processes need to be further studied and improved to include more economical and profitable methods.

Choe Kyong Mun, a researcher at the General Assay Office, has investigated the electrochemical behaviors of terbium in TbCl₃-1-ethyl-3-methyl-imidazolium tetrafluoroborate [EMIm]BF₄ electrolytes and TbCl₃-1-ethyl-3-methyl-imidazolium dicyanamide [EMIm]DCA.

X-ray diffraction analysis results of electrodeposits from TbCl₃-[EMIm]BF₄ electrolytes and TbCl₃-[EMIm]DCA electrolyte prove that metallic terbium is obtained.

For more information, please refer to his paper “Electrochemical behaviors of terbium from TbCl₃-EMImBF₄ and TbCl₃-EMImDCA ionic liquid electrolytes: a comparative study” in “Journal of Solid State Electrochemistry” (SCI).

A protective relay plays a crucial role in the normal operation of a power system and the reliable supply of electrical power. The reliable operation of an electrical power transformer is very important in maintaining uninterrupted power supply. In a protective scheme for a transformer, high speed of protection and reliable operation against clear faults are essential.

Many advanced algorithms for power system protection have been implemented on the relay protection devices based on microprocessors in programming form. To be candid, there are no references showing the results related to the design and implementation of a multi-function protective relay for a power transformer.

Im Jung Bin, a researcher at the Faculty of Electrical Engineering, has proposed a method for implementing a modularized multi-functional hardware transformer protective relay based on Field programmable gate array (FPGA) for higher speed operation of protection.

Taking the advantage of parallelism feature of FPGA, the proposed hardware transformer relay can process multi-channel input signals at high speed in real time, and concurrently estimate and process protective logics with different functions. By using a single Altera CycloneⅢ EP3C40Q240CN8 and configuring different-function protective relays, this relay allows high-speed operation which is a basic demand for protection.

This relay can operate within 1.1 cycle of power frequency.

You can find details in his paper “A Structure of Transformer Protective Relay for Implementing a High-speed Operation of Many Protective Functions Using a Parallel Processing Feature of FPGA” in “Journal of Electrical Power & Energy Systems” (EI).

Airlift pumps are considered an effective means of lifting deep ocean water due to their several advantages such as high reliability, simple structure, low cost and convenient maintenance.

The airlift pump is a fluid machine for raising liquids or slurries through a vertical pipe by injecting compressed air into the pipe near its mid position or lower end part, and its performance is therefore related to the state of multi-phase upflow in the pipe.

Rim Un Ryong, a researcher at the Faculty of Shipbuilding and Ocean Engineering, has conducted a numerical analysis of steady air–water two-phase flow in a vertical pipe of an airlift system based on a one-dimensional multi-fluid model.

He calculated the depth distributions of 6 physical quantities such as volumetric fractions and axial velocities of two phases, air density and pressure by solving the governing equations or by integrating the vector form of nonhomogeneous ordinary differential equation for two-phase flow interval.

He applied the proposed numerical model to a 7.86-meter-long vertical pipe and compared the results with antecedent theoretical and experimental results to validate its accuracy. The results showed good agreement.

If further information is needed, please refer to his paper “Numerical analysis of air–water two-phase upflow in artificial upwelling of deep ocean water by airlift pump” in “Computers and Fluids” (SCI).