Jo Jun 7, 2024
With the development of large CFB boilers, a cyclone separator with a downward gas exit that provides convenience for the construction and compact layout of boilers appeared. Later, a square cyclone separator was suggested for Π-arrangement in CFB boilers and for convenient installation of heat transfer surfaces on the inner separator walls.
Previous studies of the flow field in cyclone separators with a downward gas exit that focused only on the space between the vertex and the gas exit failed to get flow characteristics in each section of the separator.
Ryom Jun Ho, a researcher at the Faculty of Heat Engineering, has conducted a detailed simulation of the flow characteristics in a square cyclone separator with a downward gas exit.
He used the computational fluid dynamic (CFD) method to predict and evaluate the flow field and collection performance inside the square cyclone separator. In addition, he employed the Reynolds stress model (RSM) for flow field analysis in two cyclone separators with different dust exits.
The results demonstrate that the flow characteristics and collection performance of the square cyclone separator with a vertical dust exit are better than that with an inclined exit.
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Jo Jun 5, 2024
A research team led by Kim Mun Hui, a researcher at the Faculty of Electrical Engineering, has developed a small wind power generation system (SWPGS) for producing maximum power using a permanent magnet generator with two coils.
The generator with two coils ensures not only higher efficiency but also lower expense of the SWPGS than that with one coil, because it can automatically make the load curve more closely approach to the maximum power characteristic curve of a wind turbine without any control circuits.
The system consists of a three-blade horizontal axis wind turbine, a permanent magnet generator (PMG) with two coils, a rectifier, a battery, a load, etc.
PMG with two coils ensures higher accuracy of power control than that with one coil.
In the PMG, only the first coil works at low wind speed, and if the wind speed becomes higher, the second coil works, too.
As a result, the power generation system is driven at its maximum power because it is able to steadily approximate the load curve to the maximum power curve of the wind turbine.
Thus, this system can produce more electric power from the same wind resources in low wind speed areas.
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Jo Jun 3, 2024
From ancient times, Korean people have made active use of hot spring water, a natural resource especially good for medical treatment and longevity.
The old books like “Chronicles of the Feudal Joson Dynasty” give a good deal of records that the ancestors learnt about the medicinal effects of hot spring water and used it for treatment. The visual evidence of the records is the Kalsan Hot Spring Relic discovered near the Kalsan Hot Spring Sanatorium in Kudang-ri, Phangyo County, Kangwon Province.
Kalsan Hot Spring is a simple radon spring. It has been widely known as an excellent remedy for several illnesses such as dermatosis, neuralgia, chronic gastritis, arthritis, etc. from long ago.
The Kalsan Hot Spring Relic, the indoor bath house relic, consists of the building site and four water tanks in it.
On the building site are still found some properly-faced granite cornerstones and platforms and there are two water tanks in the east and west each symmetrically.
The tanks are connected to the long granite water channel with a semicircular hollow for a supply of hot spring water.
The whole floor except the parts with the tanks is covered with granite slabs.
The hot spring, which is some distance from the bath house site, is located higher than the relic, so spring water is allowed to flow down to the tanks on its own.
According to “Chronicles of the Feudal Joson Dynasty”, it is estimated that the bath house was built by the order of King Sejong, the fourth king of the feudal Joson dynasty.
Some historical records say that King Sejong saw to it that a hot spring bath house and a temporary palace were built and he personally visited it to have a hot spring cure.
Tens of meters north-east away from this relic is still found the site of the temporary palace.
All those historical records may be regarded as the evidence to prove that the Kalsan Hot Spring Relic has a long history of over 570 years.
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Jo Jun 2, 2024
Under the great love and benevolence of the Workers’ Party of Korea (WPK), a general experimental education hall composed of tens of modern laboratories equipped with advanced experimental arrangements was built at Kim Chaek University of Technology (KUT).
With the total floor space of thousands of square meters, it has 46 kinds of up-to-date equipment including those for experiments on flexible production and Internet of Things, and 35 kinds of self-made ones including a comprehensive experimental device for sea-bottom minerals.
Open experiment and practice is introduced in this hall in line with the global trend of educational development. Here, the lecturers, researchers and students are allowed to do any experiments and practice needed at any time. It will provide a solid foundation on which the university can further speed up the project to build itself into a university of research and the most prestigious university while realizing the integration of education, scientific research and production together with the bases for experiment and practice at the faculties and the Mirae Sci-tech Center.
The opening ceremony was held on April 14.
Present there were Kim Sung Du, minister of Education, and the officials, teaching staff and students of the university.
KUT President Pak Ji Min delivered an opening address.
He said:
The opening ceremony of KUT General Experimental Education Hall is being held at a time when all the people of the country are dynamically stepping up the general advance for accelerating the overall development period of Korean-style socialism, by turning out for implementing the decision of the 9th Plenary Meeting of the 8th Central Committee of the WPK.
The university, by making the most of the experimental arrangements, should wage dynamic campaigns of brains and research to solve scientific and technological problems arising in the major fields for the development of the national economy and the improvement of the people’s living standard.
All the officials, teaching staff and students should, bearing in mind the great trust and expectation of the Party that put forward KUT as a revolutionary university and the eldest son university of the country, exert all their wisdom and passion on the sacred struggle for the comprehensive development and prosperity of the country.
After the ceremony the participants looked around the general experimental education hall.
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Jo May 30, 2024
Bundle-series initiation is currently used as a method for simultaneously transmitting blast signals from a detonator to a large number of shock tubes for blasting using shock tubes and its initiation modes affect the ability and reliability of signal transmission.
For building demolition and tunneling blasting, over 50, even 100 lines of shock tubes must be simultaneously initiated by a detonator. In the meantime, a large number of shock tubes often cause initiation failures. Therefore, for shock tubes, blasting system must have not only high ability of blast signal transmission (or initiation) but also high reliability of the signal transmission on shock tubes. The methods of bundle-series initiating a large number of shock tubes are subject to possible failure modes where the ability and reliability of signal transmission on each shock tube can be strongly affected by the coupling mode of a detonator and the number of shock tubes.
To the best of our knowledge, there are no reports in the literature regarding the experiments and numerical simulation to predict or estimate the dynamic blast load and the initiating probability according to the coupling structure of a detonator with many shock tubes.
Choe Yong Chol, a researcher at the Faculty of Mining Engineering, has studied the structural influence of initiation modes on the pressure impulse generated by a detonator and transmitted to the bundle of a large number of shock tubes and the signal transmission probability, and proved the advantage of frontal bundle-series initiating mode over lateral bundle-series initiating mode.
He confirmed that the numerically obtained pressure impulse for a bundle of shock tubes shows a good correlation with the experimentally obtained signal transmission probability of a bundle of shock tubes for a variety of bundle-series initiation modes of shock tubes.
You can find further details in his paper “Influence of Initiation Modes in the Bundle-Series Initiation of a Large Number of Shock Tubes by Detonators” in “Shock and Vibration” (SCI).
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Jo May 29, 2024
It can be said that many production means and consumer goods in use today are actually associated with comminution. For example, a machine tool is made of steel, the production of which starts from mining and comminution of iron ore. Also, the production of cement used for construction of houses and buildings where we live and work begins with crushing of limestone and ends with grinding of cement clinker. Coal comminution is still included in the production of electricity indispensable for modern production and life. Thus, it can be said that comminution is an essential part in many fields of economy, consuming a greater amount of energy. Therefore, it is very important to reduce energy consumption of a comminution machine by studying its working process on scientific basis.
Breaking in a hammer crusher, a kind of machine for comminution, occurs fundamentally due to collision between the hammer and agglomerate. So it is of great importance to study the collision breakage process between the hammer and agglomerate. In particular, accurate calculation of the energy loss quantity of a hammer in the collision breakage process is one of the key issues in determining the breakage power of a hammer crusher.
Previous studies on collision crushing in the hammer crusher by DEM considered the collision process between hammer modeling in the wall and agglomerate. However, the wall in the DEM model has no mass, so its energy cannot be considered. Thus, the aforementioned simulation methods cannot calculate the energy change of the hammer in the collision process. The aim of studying the collision crushing between the hammer and agglomerate in the hammer crusher is to estimate the breakage degree of agglomerate due to collision and to predict the energy consumption in a hammer crusher by obtaining the energy loss of hammer in the collision process.
Hong Sok Gun, a researcher at the Faculty of Mining Engineering, has obtained the energy change in the hammer by making a particle model with a combination of particles rather than walls, in accordance with the nature of the DEM. From the viewpoint of attaching greater importance to the internal structure rather than the external one of the breakage process in agglomerate modeling, he made an agglomerate model starting from one perspective on internal crystal structure of minerals discussed in crystal mineralogy.
This method allows the prediction of energy to be added to the breaking tool to break the agglomerate by directly measuring the energy loss of the breaking tool in the study on the breakage process by DEM.
You can find further details in his paper “Numerical Simulation of the Collision Breakage Process between the Agglomerate and Hammer in a Hammer Crusher Using DEM” in “Shock and Vibration” (SCI).
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