Jo Oct 6, 2026
The process of sizing fine particulate material particles with different particle sizes is largely divided into sieving and sorting processes. Currently, a circular vibrating screen is used worldwide to reduce power consumption and improve classification efficiency of fine particles.
Circular vibrating screens are widely used in mining, building materials, chemical and pharmaceutical industries in the world today due to their advantages such as simple structure, small installation area, high reliability in operation and relatively high screening efficiency as compared to dry ultra-fine processing equipment.
The sieving and grading process of powder particles widely used in various sectors of the national economy also uses circular vibrating screens, air classifiers, spiral classifiers, water cyclones, etc. Although a circular vibrating screen has been used for the screening of particulate materials, it has a low throughput and does not use a multi-stage screen.
Ri Chol, a researcher at the Faculty of Mining Engineering, proposed a structural scheme of a circular vibrating screen with a two-stage screen surface for particle size separation of perlite powder particles in the process of crushing and grinding of perlite ore for the production of expanded perlite for soilless vegetable cultivation substrate, and optimized design parameters by simulating sieving operations using EDEM based on the kinetic analysis of screen surface.
The results showed that the screening efficiency was 98.87% when the eccentric mass was set to be 1kg and the phase angle between eccentric mass 45°.
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Jo Oct 5, 2026
October is a rich period when the weather gets cool, mountains and fields put on beautiful autumnal tints and plump ears of crops ripen in paddy and dry fields.
The seasonal subdivisions in October are Hallo and Sanggang.
Hallo means the time when cold dew begins to fall and it falls on October 8 this year.
Sanggang means the coming of frost and it falls on October 23 this year.
After Sanggang, the weather gets cold and the temperature difference between day and night gets bigger.
October is a busy season with harvesting and threshing of grain.
The Korean people have eaten various dishes that suit the seasonal characteristics of the October seasonal subdivisions.
Typical of them are soybean dishes and loach soup.
They also played different kinds of folk games.
Especially, children’s favourite games of hide-and-seek, hopscotch and tail-taking were spectacular.
Thus, the Korean people have created and carried on diligent and diverse working life and customs of diet, dressing and folk games suited to the seasonal characteristics of the period of Hallo and Sanggang from olden times.
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Jo Sep 29, 2026
Magnetotellurics (MT) is widely used for oil exploration. In MT, the time series of two telluric and three magnetic components of the magnetotelluric field are generally recorded at the ground surface in the Cartesian coordinate system. In practice, however, there are some difficult cases for setting two telluric lines orthogonally to record telluric components due to obstacles like roads, wetlands, rivers, cliffs, rice banks, buildings, etc. at a given MT site.
Kim Ji Yang, a researcher at the Faculty of Earth Science and Technology, proposed a method of converting telluric components recorded in non-orthogonal coordinate systems to those in orthogonal coordinate systems by means of mathematical coordinate transformation and verified its possibility and applicability through model and field tests.
This method makes it more convenient for MT field crews to choose site positions and set electric lines.
For more information, you can refer to his paper “Dealing with Non-orthogonally Measured Telluric Components in Magnetotellurics” in “Journal of Mathematical Methods in Engineering” (SCI).
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Jo Sep 28, 2026
A belt conveyor is an efficient continuous carriage machine which successively moves powder or particles such as mineral, coal, gravel, sand, fertilizer, grains as well as packaged products by using a belt. To accurately measure the total weight of bulk materials conveyed continuously or the weight of individual packaged products moving quickly on a belt conveyor is important for developing a belt checkweigher.
There have been many studies to improve weighing accuracy. Those studies are basically focused on two kinds of methods; one is model-based and the other is filter-based.
Most of those studies are focused on dynamic weighing of packaged products in fast motion on a belt conveyor. However, there has been little literature for improving weighing accuracy of the belt conveyor that successively conveys bulk materials unequally distributed on the belt.
Kim Mun Hyok, a section head at the Faculty of Automatics, proposed a new hybrid weighing scheme using the discrete wavelet transform (DWT) and adaptive noise cancellation (ANC) to more accurately weigh the successively conveyed bulk material unequally distributed on the belt.
The proposed scheme uses wavelet decomposition and reconstruction to remove noises of high frequency and uses an adaptive filter to suppress noises of low frequency.
The simulation and experimental results show that the proposed scheme optimally removes various types of noises from belt conveyors and measures the weight with accuracy degree of ±0.5%.
If further details are needed, please refer to his paper “A DWT and ANC-based continuous weighing scheme of bulk materials in belt conveyor” in “Journal of Instrumentation” (SCI).
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Jo Sep 27, 2026
Calcium fluoride (CaF2) is one of the common fluorine compounds, which is mineralogically known as fluorite. It is widely used in the production of 3-dimensionally integrated circuits, optical glass, hydrofluoric acid and ceramics, and as a flux in metallurgic industry. Owing to the increased demand for high-quality fluorite and the decrease in available resources, much attention has been paid to the study on fluorite.
There have been several studies on the characteristics of fluorite surfaces with various Miller indexes by first principles calculations. Fluorite is known as an ionic compound and it is generally cleaved along {111}, {110}, {100} and {310} planes. The cleavage along {111} plane is the easiest, followed by {110} plane and then {310} plane.
Previous studies mainly focused on the characteristics of possible surfaces with different Miller indexes and concluded that fluorite {111} surface is the safest and this is the main cleavage plane. Fluorite is an ionic crystal and calcium and fluorine layers are likely to be stacked alternatively along [111] direction. So, there may be several terminations with the same Miller index {111} surface. However, there have been few reports on the detailed characteristics of fluorite {111} surface.
Ri Chol Jin, a section head at the Faculty of Earth Science and Technology, constructed 3 kinds of possible terminations for fluorite {111} surface and calculated their surface energies, broken bond densities and relaxation degrees by using DFT calculation to determine the safest termination.
This investigation on various terminations offers a new understanding of the characteristics of fluorite {111} surface and provides useful information for further study of surface reactivity and dissolubility of fluorite.
For more information, please refer to his paper “Characteristics of Fluorite {111} Surface with Various Terminations: A DFT Investigation” in “Iranian Journal of Science” (SCI).
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Jo Sep 24, 2026
Tool steels are used for making tools to be employed for working and forming of metals, wood, plastics, and other industrial materials. They can be used for cutting tools, locators, clamps, and gauges.
Tool steel materials are put into various classifications such as high C-Cr die steel, water/air hardening tool steel, hot-work die steel, and shock-resistance tool steel. Different alloying elements such as tungsten, vanadium, molybdenum, manganese and chromium are added to modern tool steel materials to guarantee desired properties for their applications.
Each tool steel material has their own mechanical and physical properties suited for particular applications. For any specific application, several kinds of alternative tool steel material may be a choice, and it is essential to select the most suitable tool steel materials with desired properties.
Material selection is a multi-criteria decision making (MCDM) problem where materials engineers have to select the best material with the best performance among multiple available alternative materials in consideration of two or more attributes.
Many researchers have applied different MCDMs to select suitable tool steel materials for specific purposes. However, it is unknown which is better for given material selection problems.
Ma Chung Hyok, a section head at the Faculty of Material Science and Technology, proposed a best tool steel materials selection method combined with the results obtained from different MCDMs, and applied it to the selection of the best one among 10 tool steel materials in consideration of nine attributes using six popular MCDMs: rank sum ratio (RSR), simple additive weighted (SAW), technique for order preference by similarity to ideal solution (TOPSIS), grey relational analysis (GRA), VIse Kriterijumska Optimizacija Kompromisno Resenje (VIKOR), and preference ranking organization method for enrichment evaluations (PROMETHEE).
The proposed method based on the comprehensive ranks may be considered a suitable one because the result is determined in consideration of the results from individual MCDMs, and the comprehensive ranks are best coincided with the ranks from other MCDMs.
For more information, you can refer to his paper “Selection Method of Best Tool Steel Materials Using Multiple Multi-Criteria Decision Making Techniques” in “Russian Metallurgy” (SCOPUS).
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