The use of ozone gas started about a century ago. Ozone has been used to purify water polluted by microorganisms. The chemistry of ozone in aqueous solutions is complex and the direct reaction with molecular ozone and the indirect reaction with radicals generated when ozone is dissolved in water are considered for the process of water treatment with ozone.

The authors calculated the first principles of the reaction between molecular ozone and water vapour, but no first principles study of the decomposition of ozone in water has been carried out.

Choe Un Hwa, a researcher at the Faculty of Online Education, has conducted a study to select the size of ozone bubbles used for water treatment using ozone microbubbles, considering the ozonolysis characteristics in water.

She quantitatively calculated the decomposition of ozone in water using the density functional method (DFT/6-31G*). Among the four possible reactions between O₃ and H₂O in gas and water, the possibility of obtaining H₂O₂+O₂ is relatively high.

Considering that H₂O₂ and O₂ are products of indirect reactions by ozone with OH^- as an initiator and the rate of indirect reactions is very fast, the size of ozone bubbles used for water treatment can be as large as a micron size, which can increase the solubility of ozone gas in aqueous solution and improve the ozonation efficiency.

You can find more information in her paper “Ozone Micro Bubble Treatment: What is the Size of Ozone Bubble Suitable for Water Treatment?” in “Proceedings of KUTIC-2025”.

Femoral head osteonecrosis is a disease affecting patients at the age of 30-50 that usually progresses to femoral head collapse and often leads to total hip arthroplasty. Femoral head osteonecrosis frequently progresses to the subchondral fracture of femoral head, eventually leading to complete joint destruction.

Joint-preserving surgical interventions are generally more successful at earlier stages of bone involvement than after the occurrence of subchondral fracture. It means that the optimal time to evaluate and treat osteonecrosis of femoral head is before the occurrence of subchondral fracture. Early diagnosis can facilitate the application of interventions that can avoid or delay arthroplasty to some extent. However, misdiagnoses and delayed diagnoses are common due to the lack of preliminary symptoms, typical features, and internal fixation interference on radiographs.

Kim Ju Hyang, a researcher at the Faculty of Information Science and Technology, investigated the problem of extracting significant features for detecting bone diseases such as avascular necrosis and osteoporosis of femoral head from radiographic images of femoral head, and classifiers. On this basis, he proposed a method for early diagnosis of femoral head osteonecrosis by feature extraction and classifiers.

She performed feature extraction by 2D Dual tree complex wavelet transform, and early detection by support vector machine (SVM). Using 2D Dual tree complex wavelet transform on femoral radiographs, she extracted high-frequency component features based on six-way complex wavelet coefficients of femoral head images. Then, she selected the most significant features for classification among the spatial domain features and other features significant for avascular necrosis detection to construct feature vectors and designed a support vector machine classifier.

The experimental results show that the proposed method is cost-effective due to the use of X-ray images and has excellent detection performance.

If further information is needed, you can refer to her paper “Dual Tree Complex Wavelet Transform-Based X-Ray Image Feature Extraction and Early Diagnosis of Femoral Head Osteonecrosis by Support Vector Machine” in “Proceedings of KUTIC-2025”.

The annular centrifugal extractors (ACEs) are based on the principle of Taylor-vortex flow. They essentially consist of two co-axial cylinders where the outer one is stationary and the inner one is rotating. They provide very high values of mass transfer coefficient in the annular region because of high levels of power consumption per unit volume. What is more, the rotor separates two phases into the other without any carryover of one phase. With these two advantages, they are used for several applications of liquid-liquid extraction where low inventories are desired. They include metal recovery and purification in the mining industry, processing of uranium and high plutonium fuels, caustic side solvent extraction to remove cesium from nuclear waste, hydrochloric washing of polymer phases, bromination and subsequent efficient separation of brominated polymer from aqueous phase.

Ri Hui Myong, a researcher at the Faculty of Thermal Engineering, investigated the phase separation characteristics and extraction characteristics of TBP-NaNO₃ system in a 50mm annular centrifugal extractor with respect to the rotational speed and the inlet phase ratio, and derived an empirical formula for the throughput of NaNO₃ under a given operating condition.

The maximum throughput of TBP-NaNO₃ system in the 50mm annular centrifugal extractor was 12.6kg/h at a rotational speed of N=2 500r/min and an inlet phase ratio of Ro/a=1.

You can find more information in his paper “Phase Separation and Extraction Characteristics of TBP-NaNO₃ System in an Annular Centrifugal Extractor” in “Proceedings of KUTIC-2025”.