Jo Mar 8, 2026
Proper and effective exploitation and utilization of underground resources requires a good development design of deposits. What is of great importance and priority for it is to optimize the production capacity and production life of mines. The production capacity and lifetime are the basic conditions for mine design.
Economic evaluation of deposits is conducted in accordance with technical, economic and socio-political requirements. The accuracy of this evaluation depends on the validity of collected information. The economic evaluation of deposits is performed through geological, feasibility and economic study stages, and the information required for this process should be collected and processed. The production capacity and lifetime of mines are just preliminarily evaluated in the feasibility study stage.
In the literature, the preliminary evaluation of the production lifetime of a deposit (or mine) is presented. Here, the empirically obtained Taylor Formula is used.
Ri Kwang Su, a section head at the Faculty of Earth Science and Technology, further improved the empirically obtained Taylor Formula through mathematical modeling.
He applied a method of comparing the results by analyzing the regression with SPSS 20 with the data used in making an empirical formula for the preliminary assessment of the life of deposits.
The results showed that the new power equation is the most suitable and it also has smaller absolute and relative errors than the Taylor Formula.
You can find his paper “Improvement of the Taylor-Formula for Preliminary Assessment of the Optimal Lifetime of the Ore Deposits” in “Proceedings of KUTIC-2025”.
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Jo Mar 6, 2026
The microwave cavity filter, which is operated by coaxial resonators with high Q-factors above 4 000, has high power and high performance.
Coupling matrix synthesis is the most important step in the design of microwave filters. This is because coupling matrix is the most critical in mapping the theoretical filter characteristic polynomial to the parameters of a physical filter model.
The coupling matrix of a microwave cavity filter is not a feasible topology, so it must be reconstructed by performing a similarity transformation. The reconstruction of coupling matrix using the rotation matrix is not suitable for lossy filter design and there are several problems in reconstructing the coupling matrix, which necessitates different approaches.
Kim Chol Jin, a researcher at the Faculty of Communication, proposed using hyperbolic reflection matrix in the coupling matrix synthesis to design a microwave cavity filter for use in mobile station remote radio units.
First, he synthesized an orthogonal matrix that can simplify the complex coupling matrix obtained in the design of a microwave filter with loss considerations. Then, he solved the problem of code control of cross-coupling arising in reconstructing a general coupling matrix.
The experimental results show that a coupling matrix is reconstructed to have desired topology and that a hyperbolic reflection matrix can reconstruct a complex coupling matrix.
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Jo Mar 5, 2026
Although many serious problems are being caused due to the air pollution and rapid fossil fuel depletion, coal combustion is still a major method for energy generation. Therefore, most heat power plants use pulverized coal as the fuel for steam boilers. Even in this case, however, there are still many problems such as expensive cost of oil, difficulty in its storage and supply, stabilization of ignition and/or burning caused by hot corrosion of surface and heavy metals pollution. These problems require new ways of ignition and burning stabilization.
Due to additional pulverization of coal granules, excitation and dissociation of molecules, and production of free radicals, plasma-assisted combustion technique has drawn considerable attention as a promising method for enhancing combustion.
Plasma-assisted combustion can be classified into equilibrium plasma-assisted combustion (EPAC) and non-equilibrium plasma-assisted combustion (NEPAC). Most equilibrium plasma burners use a plasma torch of arc jet, which has some disadvantages such as fast consumption and frequent replacement of electrodes, complexity of cooling system and low energy efficiency. NEPAC produces incomparably higher vibrational temperature and electron temperature than the translational temperature in non-equilibrium plasmas. Therefore, the non-equilibrium plasma is of particular interest as far as combustion is concerned. The plasma generated by gliding arc discharge that includes both thermal effect and non-equilibrium characteristics is quasi non-equilibrium plasma suitable for fuel combustion.
Ri Thae Nam, a researcher at the Faculty of Physics, built a pulverized coal burner and conducted some experiments, on the basis of the understanding of the characteristics of non-equilibrium plasma generated by gliding arc discharge.
First, he performed a test on the experimental set-up composed of a plasmatron and a burner using gliding arc discharge with two electrodes. He drew distinctive temperature distribution curves at four measuring points of the set-up and confirmed the combustion possibility of low-grade coal. Then, he constructed a combustion system of pulverized coal for boiler ignition and obtained stabilized pulverized coal flame through the secondary burner. Finally, he analyzed the possibility and advantage of boiler ignition by the proposed combustion system in contrast to that of heavy oil or natural gas.
The analysis results showed that the introduction of the proposed combustion system could bring major economical effects by reducing the energy needed for ignition and combustion of coal.
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Jo Mar 4, 2026
The 39th Science and Technology Festival of Kim Chaek University of Technology took place from Feb. 24 to 27 on the theme “Steady Development of Sci-tech Capability”.
The festival was divided into 7 panels including metal and chemistry, machine and transport, etc. Presented there were more than 260-odd sci-tech achievements including “Robotization and streamlining of precision mold production process” and “Establishment of active lime production process”.
During the festival, there were presentation and examination of sci-tech proposals and technical exchange among visitors. Trophies, certificates and prizes were awarded to the highly-praised units and individuals.
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Jo Feb 28, 2026
NOMA (Non-Orthogonal Multiple Access) is the main technology of 5th generation communication system for controlling the throughputs of users by using power allocation corresponding to information transmission time.
In the previous researches, they assumed that all users have the same channel weights in the aspects of power allocation and sum rate.
However, their assumption makes it difficult to simultaneously satisfy the sum rate and user fairness.
Kim Tong Jin, a researcher at the Faculty of Communication, proposed an improved energy harvesting scheme to achieve the maximum sum rate by using weighted users.
The proposed scheme is based on an energy harvesting model and the sum rate is expressed by the throughput of the Nth user.
He set the channel weight of the Nth user to be a certain value and calculated the weights of other users by using the weight of the Nth user so that all users have the same rate and the scheme has the maximum sum rate. Then, he assumed that the sum rate does not depend on the number of users and the channel weight of the Nth user. Under this assumption, he calculated the optimal information transfer time to maximize the sum rate.
He compared the new scheme with the previous one in terms of the channel weight for the Nth user and information transfer time. The results showed that when the number of users in one source block is increased, the sum rate and user fairness are improved significantly.
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Jo Feb 27, 2026
Predicting the hydrodynamic load on a body entering the water is important in the field of marine engineering. When a ship moves in water, water entry adversely affects ship motion and can even damage the ship structure.
Therefore, water entry problems have been widely investigated with experimental, theoretical and numerical methods.
According to preceding researches, however, the moving particle semi-implicit (MPS) method has not been widely applied to water entry problems.
Pak Chol Jun, a researcher at the Faculty of Naval Architecture and Ocean Engineering, has investigated hydrodynamic load acting on a two-dimensional (2D) wedge during water entry by means of the widely-used moving particle semi-implicit (MPS) method.
First, he proposed two techniques for enhancing the performance of MPS and a symmetry domain technique for reducing the computational cost. Additionally, he proposed a fluid–solid coupling algorithm using the MPS method.
The comparison results to verify the accuracy of the proposed techniques show that the MPS with the proposed schemes can provide reliable numerical prediction for water entry problems.
For further details, you can refer to his paper “Numerical Investigation on Water Entry of Two-dimensional Wedges with a Moving Particle Semi-implicit Method” in “Journal of Marine Science and Application” (SCOPUS).
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