Energy harvesting is a prospecting solution for enough energy supply to wireless MSs (Mobile Station) in the communication. MSs use energy to transmit information to an eNodeB or to charge their batteries by received signals.

Unfortunately, MSs do not harvest energy and transmit information at the same time in practice. In order to solve this problem, a researcher proposed a harvest-then-transmit protocol and assumed that terminals employ time division multiple access (TDMA) for information transmission. Although using the harvested energy has many benefits, the dependence of MSs has a negative effect on data rates. Consequently, it is necessary to explore several methods for improving energy-bandwidth efficiency.

In the meanwhile, the most important factors in 5G mobile system are MMF (Maximum Fairness), SR (Sum Rate) Maximum and EE (Energy Efficiency) Maximum. Thanks to these factors, it has good features in contrast to OMA system.

Kim Tong Jin, a researcher at the Faculty of Communication, has investigated a time-allocation and terminal weight method to improve fairness while maximizing data rate in 5G mobile communication systems.

The simulation results show that the proposed scheme is superior in both data throughput and terminal fairness.

For further details, please refer to his paper “Improvement of Maximum Data Throughput and Terminal Fairness using Channel Weights in 5G Mobile System” in “Proceedings of KUTIC-2025”.

Power sharing and voltage quality are challenging problems in islanded microgrids with nonlinear loads. Distributed generations (DGs) can be used to improve the power quality in microgrids. However, when several DGs are used for voltage harmonic compensation, the conventional droop control can cause poor harmonic power sharing among the DGs due to mismatched line impedance.

Kim Sung Hyok, a section head at the Faculty of Electrical Engineering, proposed a regulation method of virtual harmonic impedance for proportional harmonic power sharing. This method does not require the prior knowledge of line impedance.

The simulation results showed that the proposed method is effective for proportional sharing of harmonic power by reducing the total harmonic distortion (THD) of voltage at point of common coupling (PCC).

For more information, you can refer to his paper “Distributed Regulation of Virtual Impedance for Voltage Harmonic Compensation in Islanded Microgrids” in “Proceedings of KUTIC-2025”.

With the rising demand for satellite communications, the use of low-earth orbit (LEO) satellites is increasing.

MPPT control is more suitable for LEO satellites with relatively short solar cycles and low weight margins. However, there is a tendency to unconditionally use MPPT control regardless of the mission and orbit conditions of LEO satellites, from the existing experiences.

Therefore, it is important to reduce the peak value of battery charging current by reducing the mass of SAR and applying MPPT control according to mission and orbit conditions. It is also necessary to study simple charge control techniques suitable for SAR, including the method of increasing efficiency based on simple switch signal control.

Ho Kum Song, a researcher at the Faculty of Aerospace Engineering, proposed new direct charging control suitable for power systems applicable to lightweight, high-reliability LEO satellites, thus reducing manufacturing cost and increasing efficiency.

The simulation results show that the proposed SAR with direct energy transfer (DET) and constant voltage (CV) control is not significantly affected by environmental conditions and it is more suitable for space environment than conventional SAR.

If more information is needed, please refer to his paper “High-Efficiency Operation of Power Controllers using Solar Plate in Low Earth Orbit Satellites” in “Proceedings of KUTIC-2025”.