Jo Feb 9, 2026
Accurate knowledge of slag level in iron-making processes is a key issue for scientific furnace control to increase productivity and ensure safe operation.
The level measurement method can be broadly divided into contact and non-contact. Contact methods are pressure, float, electric resistance and conduction methods and non-contact methods include microwave, ultrasonic and radiation. The level can be measured by selecting a suitable method with the characteristics of measurement objects and the measurement environments in consideration.
In the Hismelt process, the core is a smelting reduction vessel, where the molten steel is tapped in a continuous mode by a siphon front, unlike conventional blast furnaces, and the slag discharge is periodic. Contact methods are not suitable for measuring the slag level in a closed Hismelt furnace, but non-contact methods are needed. Radiation method is appropriate for measuring the level of boiling slag in a closed furnace like a Smelt Reduction Vessel (SRV).
With an attempt to evaluate the level of slag in a Smelt Reduction Vessel (SRV) where hot air is introduced into a closed furnace and iron ore is melted, Ri Hye Won, a researcher at the Institute of Analysis, proposed a method of level measurement. In this method, radiation source and radiation detectors are installed outside the furnace and each detector is operated like a relay.
He selected a 137Cs source with radioactivity of 3.2Ci as the radiation source and placed five NaI(Tl) scintillation detectors uniformly in the interval from the copper cooling box position to the hot wind lance, the interface of slag and molten metal, to measure the level of slag flow zone (2m).
The Monte Carlo simulation and experiments verified that slag levels in the range of 10~200cm from the copper cooling box could be estimated with accuracy of ±10cm.
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Jo Feb 8, 2026
The Visible Light Communication (VLC) is the technology for sending information by flickering visible light at insensible speed. This is the principle of sending data by detecting "On/Off" of lights, where "On" is digit "1" or “Off” is digit “0”. VLC is available where radio propagation is limited such as the interiors of hospitals or companies. In addition, because communication is available only in the visible range of LEDs, high security is guaranteed. Since LEDs are flickered at tremendously high speed, both illumination and communication are possible.
For the indoor Visible Light Communication (VLC) based on white LED as a new communication system, a channel model has not been established. Its measurement and establishment are still in its exploratory stages.
Kim Hyon Chol, a researcher at the Faculty of Communication, has summarized the exposition of indoor VLC links and conducted a theoretical and experimental analysis of the photon model of the VLC system from a detailed point of view.
The proposed indoor light channel models can be used in VLC for several indoor environments.
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Jo Feb 7, 2026
Wang San Ak, who is of Koguryo origin, was a proud musician of the Korean nation. He brought about the beginning of Komungo music by devising a national instrument Komungo in the first half of the fourth century, developing its execution and writing pieces for it.
Wang San Ak, who had an intimate acquaintance with music, decided to devise a new instrument with clear sound and great volume and at the same time convenient for playing and suitable for musical performances of national emotion. He, then, made painstaking efforts, finally succeeding in making a Komungo, an instrument with six strings.
He liked playing the Komungo as it has refreshing tone color and is suited to the musical performances of national emotion, and thus, he developed various execution skills and wrote numerous pieces for it.
As its deep and dull stirring tone color and vigorous and bold execution were congenial to the vigorous and optimistic emotion and temperament of Koguryo people and it was also convenient for playing pieces of national coloring, Komungo spread rapidly far and wide and became a representative string instrument of Koguryo.
Later, Koguryo’s Komungo was known to Paekje and Silla, and even to the neighboring countries.
A high-level Komungo solo “Komungosanjo”, which intensively demonstrates traditional Komungo execution, was written in the modern age.
After liberation, Komungo music further developed thanks to the correct policy of literature and art of the Workers’ Party of Korea. Komungo ensemble “Tapping” has been loved very much by the Korean people as it is rich in national color and its vigorous and powerful melody vividly reflects the struggle of the people in the Chollima era.
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Jo Feb 6, 2026
PTC (positive temperature coefficient) thermistors based on BaTiO3 semiconducting ceramics are important devices for ferroelectric materials.
Due to their great temperature coefficient of resistance, barium titanate and its related compounds are ideal candidates for producing various PTC components. Particularly, Ba1-xSrxTiO3(x=0~1) ceramic material-based PTC thermistors have nonlinear characteristics around the Curie point, which can be enhanced by the addition of some minor impurities such as Cu and Mn.
Jo Myong Chol, a researcher at the Institute of Semiconductor, has investigated the effects of Mn addition on the dielectric properties and microstructure formation of BaTiO3-based ceramic chips and the effects of heating rate on PTCR response of barium-strontium titanate (BST) ceramics doped with Mn dopants.
Mn addition works as a sintering agent, which influences the densification behavior of the overall ceramic material. The dielectric constant increases to as high as 5 800 (at 25℃) and the dielectric loss decreases by 1% when Mn-content is added properly. This shows that the phase formation, density, microstructure and electrical properties of co-doped BST ceramics containing sintering additives are strongly affected by heating rate.
The highest densification during sintering occurs at the heating rate of 5 or 20℃/min. There is a general trend of decrease in effective resistivity with increasing heating rate, which could be attributed to the decrease in grain size. However, when the heating rate went from 5 to 20℃/min, there was a slight increase in resistivity, which may have been due to the increased proportion of crystallized secondary phases in the most rapidly heated sample, but the reasons for this are uncertain. Thus, it can be concluded that 3 and 5℃/min are the best heating rates for favorable PTCR effects.
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Jo Feb 3, 2026
From olden times, the Korean people have celebrated Jongwoldaeborum (lunar January 15) as one of the great folk holidays, and they made it a traditional practice to make several kinds of dishes including ogokbap, yapbap, laver-wrapped rice, nine kinds of seasoned edible grass, noodle, etc. and enjoy them on this day.
Ogokbap is boiled rice admixed with four other staple cereals.
The ingredients usually included five kinds of cereal―white rice, hulled glutinous millet, polished millet, hulled barley and adzuki beans, but the five kinds of cereal were not fixed. Here is a recipe for ogokbap.
First, adzuki beans are soaked in water.
Second, hulled glutinous millet and polished millet are washed.
Then, white rice, adzuki beans and hulled barley are boiled together. After some time of boiling, hulled glutinous millet and polished millet are placed upon the mixture.
Finally, the fire is weakened for enough steaming.
What is important is to add less water for glutinous rice than for common boiled rice.
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Jo Jan 30, 2026
Mixing is an important technique for improving product quality in various manufacturing processes. Various mixers are used in the mixing processes of many fields including iron works, food industry, cosmetics and construction.
Among various types of mixers, a twin spiral mixer has the advantage of small volume and continuous mixing. In a twin spiral mixer, the left and right spiral wings attached to two axes rotating in opposite directions alternately work by advancing the material in one direction. First, the left spiral wing rotates and contacts material particles, advancing them and sending some of them toward the right spiral wing. The right spiral wing then approaches the position where it can contact the particles. Next, the left spiral wing releases the particles, and the right spiral wing comes into contact with them, advancing them and sending some toward the left spiral wing. Thus, in the twin spiral mixer, mixing is achieved by a simple cross action of the spiral wings that send some particles toward each other. From this mixing principle, the mixing degree in the twin spiral mixer is determined by the number of wings that interact with particles. In addition, due to the single mode of mixing, the attainable mixing degree is not high, and therefore, the length of the mixer must be long inevitably to increase the mixing degree.
Generally, various methods of structural and working parameters optimization have been widely used to improve the performance of machines and equipment. However, these methods are not sufficient to fundamentally change the performance characteristics and they have certain limitations. In the twin spiral mixer, it is also difficult to achieve the improvement in the mixing degree by optimizing the structural parameters, since the mixing process is realized by a simple cross action of the spiral wings.
Ri Song, a researcher at the Faculty of Mining Engineering, evaluated the mixing degree by simulating the mixing process of a twin spiral mixer by DEM (discrete element method) and then, based on this, he proposed a plan of increasing the mixing degree by installing inverse spiral wings at regular intervals in a twin spiral mixer to change the mixing mode.
Comparing the mixing degree for the conventional twin spiral mixer and the twin spiral mixer with inverse spiral wings, it was 0.779 7 for the conventional mode, 0.801 3 for the 2:1 mode, 0.81 for the 3:1 mode and 0.790 7 for the 4:1 mode, which means the 3:1 mode was the best, and the outputs from simulations were 89.1W, 429.7W, 287.8W and 151.5W, respectively.
You can find more details in his paper “Study on improving the mixing degree of a twin spiral mixer by changing the mixing mode using inverse spiral wings” in “Journal of the Brazilian Society of Mechanical Sciences and Engineering” (SCI).
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