Vanadium redox flow batteries (VRFBs) are large-scale electrochemical energy storage systems that enable the supply of stable and reliable power from wind or solar energy. Proton exchange membrane fuel cells (PEMFCs) are efficient and environmentally friendly electro-chemical energy conversion systems that produce only water and heat with clean hydrogen produced using renewable energy as fuel. On the other hand, EHC is an advanced electrochemical system that is indispensable for hydrogen energy cycle systems that purify and compress hydrogen simultaneously.

Sulfonated polyetheretherketone (SPEEK) membranes have been widely regarded as inexpensive proton exchange membranes for electrochemical energy systems such as VRFBs, PEMFCs and EHC due to their ease of fabrication, low cost, good proton conductivity, and excellent thermal and chemical stability.

General requirements for these applications are high proton conductivity, chemical and mechanical stability and impermeability of fuels and oxidants.

In order to improve the performance of membranes, Ju Il Myong, a researcher at the Faculty of Chemical Engineering, developed SPEEK/TiO₂ nanopaper composite membranes with TiO₂ nanopaper as a backbone and SPEEK polymer as a proton conducting medium, and evaluated their physicochemical properties.

Compared to pristine membranes, the SPEEK/TiO₂ nanopaper composite membranes show nearly twice tensile strength, about 1/3 of vanadium permeability and low hydrogen gas permeability, and better performance and long lifetime in VRFB, PEMFC and EHC systems. The experimental results show that SPEEK/TiO₂ nanopaper composite membranes can replace commercial Nafion® membranes in electrochemical energy systems.

If more information is needed, please refer to his paper “SPEEK/TiO₂ Nanopaper Composite Membranes for Electrochemical Energy Systems” in “Proceedings of KUTIC-2025”.

Recently, environmental protection has become a very important issue in the world. Many enterprises are recycling as much waste material as possible from their production processes, and they are concerned about energy consumption and environmental issues of production processes.

Generally, biological sewage treatment is widely applied to treating sewage containing a large amount of organic matter including farm sewage and domestic sewage. The most energy-consuming process in these methods is the blowing equipment of the aeration system for supplying dissolved oxygen to sewage. Therefore, improving aeration facilities to increase oxidation efficiency is important to reduce power consumption.

Use of microbubbles in the aeration process of biological sewage treatment has been reported to significantly improve sewage treatment parameters, especially with a significant reduction in energy consumption.

Ji Chol Hyok, a researcher at the Instititute of Nano Science and Technology, investigated the effect of introducing fluidic oscillation into a sewage aerator to enhance oxygen transfer efficiency and generate smaller bubbles.

The experimental results showed that the overall wastewater treatment parameters were improved in microbubble aeration combined with FOs.

You can find more information in his paper “Improving the Efficiency of Biological Sewage Treatment by Applying Porous Membrane Microbubble Generating System Coupled with Fluidic Oscillators” in “Proceedings of KUTIC-2025”.

The dependence of the differential negative resistance of a unijunction transistor (UJT) on external behavior is used to develop a new family of microelectronic transistors for measuring temperature, magnetic field, light radiation and pressure. The magnetic sensitivity of UJT in the presence of an externally applied magnetic field depends on this current magnetic effect. To our knowledge, there are no published results regarding the magnetic sensitivity of structures with p⁺ diffusion rings and surface recombination center regions.

Kim Sang Hyok, a section heat at the Institute of Semiconductor, proposed a unijunction transistor (UJT) of a new structure with enhanced galvanomagnetic effects by using a p⁺ diffusion ring and improved magnetic sensitivity by forming a recombination region on the surface with an emitter.

He fabricated the device on an n-type <111> orientation silicon mono-crystalline wafer with resistivity of 200Ω·cm and thickness of 250㎛ by using the standard CMOS technology.

The experimental results show that it had the highest magnetic sensitivity of 80V/T when the ratio of Emitter-Base 1 distance to diffusion length is about 1:0 and the width of the Base layer limited by the p⁺ diffusion loop is twice the Emitter width.

You can find more information in his paper “A New Structure of High-Sensitivity Magnetically Unijunction Transistor” in “Proceedings of KUTIC-2025”.