Jo Oct 9, 2026
In order to improve the academic skills of EFL (English as a foreign language) learners, due attention should be paid to teaching the exquisite principles of mind maps to put it into practice. Mind maps help facilitate mastery of contents such as logical grasping, integrating, systematizing and simplifying.
By using mind maps, they can facilitate their thinking and easily elaborate and present information. This is the process of understanding the contents of complicated system or structure, and at the same time, the process of learning the underlying principles. While preparing a presentation, they may encounter many difficulties in organizing the structure of summarized speech, which can be solved by using mind maps. By applying mind maps to presentation, they can acquire scientific research, problem-solving and critical thinking abilities. And they will also be well versed in correct formality and usage of academic speech, and correct mode and viewpoint of thinking such as logical development, demonstration, criticism and argument.
Kim Hye Won, a researcher at the Faculty of Foreign Languages, conducted an experimental research on the possibility of improving the EFL learners’ language skills and thinking abilities by applying mind mapping in the course of preparing and performing presentations, and proved its effectiveness.
She introduced the quasi-experimental design to two classes under study. She collected and analyzed data through tests and questionnaires to find out if there is any improvement. She found out that there was a remarkable difference between the two classes.
In conclusion, the results of her study show that mind maps are influential in improving EFL learners’ presentation abilities, i.e. language skills and thinking abilities.
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Jo Oct 8, 2026
A high-voltage electric heater (HVEH) is often used to manage fluctuations in renewable energy sources. The HVEH offers several advantages such as high electro-thermal power of thousands of kilowatts, low investment compared to its high thermal power and no need for transformers thanks to the direct supply from electric power net. However, it is difficult to predict thermal power capacity in the design step because it depends on the temperature, velocity and specific resistance of fluid.
In order to decrease the thermal power to hundreds of kilowatts and to guarantee operation safety, the whole electrical resistance of a heater should be increased. This can be realized through innovation of the internal structure of electric heater and some adjustment to its operation parameters because increasing only the electrical resistance of liquid is limited.
In order to solve this problem, Jang Ki Ho, a section head at the Faculty of Thermal Engineering, proposed HVEH of new structure, i.e. 10kV HVEH with PTF insulation tubes, and investigated the influence of fluid flow, temperature field and electrical field on thermal power in the design stage.
He presented a mathematical model representing the combination field of heat, fluid and electricity, and calculated it at a velocity of 0.1-0.5m/s and the temperature range of 20-80℃ with COMSOL. Then, he compared the predicted thermal power with a high-voltage electric heater under the identical operating conditions.
The results showed that the thermal power is acceptable below 650kW and the insulation tube is appropriate with a geometrical size of φ 0.17m×L 0.5m.
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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 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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