Jo Dec 12, 2025
Lithium and its compounds have been widely used in several fields including battery, aerospace and light metal alloys due to their special properties. Recently, gradual exhaustion of lithium resources on land makes it important to extract lithium from seawater and salt lake brine which are rich in lithium.
There are several methods for recovering lithium from lithium resources including precipitation, solvent extraction and adsorption. Among them, adsorption method is suitable for recovering lithium from seawater and salt lake brine due to its simple process and high recovery.
Inorganic adsorbents are widely applied in the adsorption method. Among them, ion sieve materials are most widely used. At present, there are two types of lithium ion sieves―manganese type and titanium type. The ion sieve of manganese type has a disadvantage of big dissolution rate of manganese. Therefore, research on the titanium type with higher chemical stability is becoming more intensive.
Ri Song Ho, a section head at the Institute of Analysis, has prepared a titanium-type lithium ion sieve for recovering lithium from seawater and salt lake brine, and investigated its characteristics.
First, he prepared the precursor of lithium ion sieve (Li2TiO3) by the solid state reaction with lithium carbonate (Li2CO3) and titanium dioxide (TiO2) as raw materials. Then, he prepared a lithium ion sieve (H2TiO3) by extracting lithium from the precursor with HCl solution.
The extraction rate of lithium and the dissolution loss rate of titanium are 91.23% and 0.2%, respectively, during HCl treatment of the precursor. The equilibrium adsorption capacity of lithium on the prepared ion sieve is 38.8mg/g.
...
Jo Dec 9, 2025
Currently, research on parameter tuning methods is active due to the widespread use of PID controllers in industrial practice. Many studies have been carried out on self-tuning methods to tune the parameters of PID controllers with varying plant parameters, bringing about remarkable successes.
Meanwhile, the Particle Swarm Optimization (PSO) algorithm is a kind of optimization method based on the theory of cluster intelligence, which has been widely applied in the field of function optimization, neural network learning, multiobjective optimization, fuzzy control system, etc. The population optimization algorithm is easily applicable to various types of problems because there are no complex crossover and mutation operations like in genetic algorithms. The greatest advantage of PSO algorithm is its fast convergence speed, simplicity of evolution operation, low computational cost and small number of parameters used in it.
The T-S fuzzy model approximates nonlinear characteristics, and inference using it can be used as a tool to implement controllers or fuzzy models with optimal and adaptive functions because it is simple and convenient for mathematical analysis and it can be easily combined with PID control or adaptive control.
Kim Yong Su, a researcher at the Faculty of Automatics, has proposed a method for designing a PID controller, based on the characteristics of PSO algorithm and T-S fuzzy model.
According to the proposed method, you first use the PSO algorithm to determine the position of a dominant pole which minimizes the judge function consisting of Integral of Absolute Error (IAE) and overshoot value and then express it as a T-S fuzzy model to determine the parameters of a PID controller using fuzzy inference.
The proposed method allows you to get both the optimal dominant pole and the exchanging frequency at the same time, and to get a good control result as the overshoot value is small.
...
Jo Dec 5, 2025
Recent rapid development of mobile devices such as tablets and smartphones makes it possible to take a university course anywhere anytime and it has brought about a new type of learning; m-learning.
Downloading has been a common method for mobility. However, it is inevitable to download all data even when you need a certain part of a video clip or when you just need to go through it. This wastes communication cost and requires a user to wait until downloading is completed. In addition, it needs space for storing the downloaded data. Thus, streaming service of mobile education is a breakthrough in the world of education as a means of learning using Internet technology and mobile telecommunications devices.
Ri Ye Bok, a researcher at the Faculty of On-line Education, has proposed a SCORM-based package model for streaming service in distance education through mobile network.
The proposed model enables two kinds of service—downloading and streaming, using the same contents, thus not only guaranteeing the safety of data, but also saving memory space and providing convenience of management.
It can be easily implemented on various distance education sites as it converts learning contents into those for Android-based devices to provide several kinds of service in distance education systems based on the SCORM standard model.
...
Jo Nov 28, 2025
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).
...
Jo Nov 27, 2025
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).
...
Jo Nov 26, 2025
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).
...