Jo Oct 13, 2026
The fixed point theory provides a very powerful tool in mathematics and many other scientific fields such as nonlinear analysis, integral equations and differential equations. What is interesting in a recent study on the fixed point theory is the generalization of metric space (MS).
By generalizing the concept of MS in the fixed point theory, many mathematicians presented new concepts such as b-metric space, triple controlled metric type space and triple-composed metric space. Some other authors defined a new notion called S-metric space (S-MS). Later, some mathematicians introduced new concepts for generalizing S-MS by using the ideas of earlier space concepts. Sb-MS and triple controlled S-metric type space (TC-S-MTS) are typical examples.
Kil Chol Jin, a lecturer at the Faculty of Applied Mathematics, proposed a new concept of triple-composed S-metric space (TCS-MS). He got motivation from the concepts of TCMS and S-MS while analyzing the recent research results on S-MS.
TCS-MS is a new concept that uses the composition of three functions rather than the multiplication of three functions, unlike the recently introduced TC-S-MTS.
He presented some meaningful examples showing that triple-composed S-metric space is a real generalization of S-metric space and Sb-metric space. In addition, he proved a fixed point result for Proinov-type contractive mappings in triple-composed S-metric spaces.
For more information, please refer to his paper “Triple-Composed S-Metric Spaces and Related Fixed Point Results” in “Proceedings of KUTIC-2025”.
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Jo Oct 12, 2026
Due to the frequent occurrence of accidents in the sea, it is an important requirement to predict accidents in advance and take safety measures from an early stage.
At present, assessment of accident risks is referred to as the question of how to predict risks and take measures. Intensifying research on the global regulatory tool, the Formal Safety Assessment (FSA), is important in finding and reducing ship accident risks from early stages by taking safety measures.
Jon Kwang Sik, a researcher at the Faculty of Naval Architecture and Ocean Engineering, proposed a methodology for evaluating ship safety and providing safety measures with a focus on the risk of possible collision accidents by applying the FSA method, which has been widely adopted.
He established a measure scheme for avoiding or minimizing damage by predicting damage results based on the identification of many risk indexes associated with collision accidents, and conducted a comparative analysis to propose the most appropriate measures to prevent collision accidents.
The proposed method will play an important role in planning regulations for assessing the safety of ships and taking safety measures in relation to possible marine accidents as well as collision accidents in all ships in the future.
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Jo Oct 11, 2026
Tantalum and niobium are the most important materials for various sectors of the national economy. They are used for structural steel, superconducting, electron tubes, cemented carbide, steel modifiers, scientific lens additives, dental prosthetic materials, etc.
Tantalum and niobium are found in over 130 kinds of minerals, composed of tantalate and niobate or complex oxide of titanium-niobium-tantalate. The widely used minerals in the production of metallic tantalum and niobium are tantalum-columbite, pyrochlore, rare-earth perovskite, etc. Among them, pyrochlore is a very valuable mineral due to its high content of rare earth elements as well as tantalum and niobium.
The separation methods of tantalum and niobium include fractional crystallization of fluoride complexes, solvent extraction, ion exchange, distillation of chlorides, and selective reduction of NbCl5. Among them, those that have been commercialized for many years are fractional crystallization and solvent extraction.
Recently, the development of inexpensive and efficient solvent extractants by many researchers has led to the separation of tantalum and niobium by solvent extraction methods. Although the use of neutral extractants such as MIBK and TBP in hydrofluoric or hydrofluoric-sulfuric acid media is common for the separation of tantalum and niobium, the separation of tantalum and niobium from sulfuric acid decomposition has been rarely studied so far.
Kang Chung Su, a section head at the Faculty of Chemical Engineering, conducted a study to separate the impurities from the aqueous leachate of pyrochlore sulfate decomposition product and to separate tantalum and niobium with octanol as the extractant.
After keeping the pH of the sulfate leaching solution at 2 and mixing 100% octanol to an aqueous phase/organic phase ratio (A/O) of 1:1, the extraction at room temperature for 15min resulted in more than 99% tantalum extraction, but no niobium extraction. After stripping of the tantalum-loaded octanol with distilled water at room temperature for 20min at a phase ratio of 1:1, more than 99% tantalum was stripped. When ammonia solution is added to the tantalum pregnant strip solution to pH 4.5-5.5, tantalum hydroxide is precipitated and when ammonia solution is added to the raffinate to pH 6-7, niobium hydroxide is precipitated.
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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 7, 2026
Ulmil Pavilion is a structure in Kyongsang-dong, Central District, Pyongyang, built on the site of northern command post in the inner wall of the Walled City of Pyongyang of Koguryo.
The name Ulmil is derived from a word meaning a flat upper hill.
Besides, according to legend, it was so named because in olden times Saint Ulmil came down from Heaven to have a good time there, and another legend runs that General Ulmil of Koguryo fought to defend the place.
The pavilion was first built in the mid-6th century as the northern command post of the keep of the Walled City of Pyongyang in the period of Koguryo and rebuilt in 1714.
Afterwards, it was repaired several times.
The embankment of the pavilion is about 11 metres high, so it looks like a very tall structure.
The pavilion towering above the embankment is also called “Sahojong” in a sense that it is situated in a picturesque place with an unobstructed, extensive view.
As it is decorated in the style of gorgeous morutanchong, it goes well with the surrounding natural environment.
The scene around the pavilion is among the eight famous scenes of Pyongyang, called “greeting the spring on Ulmil Pavilion”.
Ulmil Pavilion is associated with the Korean nation’s history of struggles against foreign aggressors, including Pyongyang people’s fight against Japanese invaders in the period of the Imjin Patriotic War (1592-1598).
The pavilion now serves as a resting site for working people and students visiting Moran Hill.
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