Sejong University

About: Sejong University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Graphene & Computer science. The organization has 5498 authors who have published 15236 publications receiving 330762 citations.

Chaotic random spare ant colony optimization for multi-threshold image segmentation of 2D Kapur entropy

Abstract: Although the continuous version of ant colony optimizer (ACOR) has been successfully applied to various problems, there is room to boost its stability and improve convergence speed and precision. In addition, it is prone to stagnation, which means it cannot step out of the local optimum (LO). To effectively mitigate these concerns, an improved method using a random spare strategy and chaotic intensification strategy is proposed. Also, its selection mechanism is enhanced in our research. Among the new components, the convergence speed is mainly boosted by using a random spare approach. To effectively augment the ability to step out of LO and to refine the convergence accuracy, the chaotic intensification strategy and improved selection mechanism are applied to ACOR. To better verify the effectiveness of the proposed method, a series of comparative experiments are conducted by using 30 benchmark functions. According to all experimental results, it is evident that the convergence rapidity and accuracy of the proposed method is better than other peers. In addition, it is observed that the capability of enhanced RCACO is more reliable than other techniques in stepping out of LO. Furthermore, an excellent multi-threshold image segmentation method is proposed in this paper. On this basis, image segmentation experiments at low threshold levels and high threshold levels are also respectively carried out. The experimental results also adequately disclose that the segmentation results of RCACO for both multi-threshold image segmentation at a low threshold level and high threshold level, are even more satisfactory compared to other studied algorithms. An online homepage supports this research for access to sharable codes, any question and info about this research at https://aliasgharheidari.com .

Secure Surveillance Framework for IoT Systems Using Probabilistic Image Encryption

Abstract: This paper proposes a secure surveillance framework for Internet of things (IoT) systems by intelligent integration of video summarization and image encryption. First, an efficient video summarization method is used to extract the informative frames using the processing capabilities of visual sensors. When an event is detected from keyframes, an alert is sent to the concerned authority autonomously. As the final decision about an event mainly depends on the extracted keyframes, their modification during transmission by attackers can result in severe losses. To tackle this issue, we propose a fast probabilistic and lightweight algorithm for the encryption of keyframes prior to transmission, considering the memory and processing requirements of constrained devices that increase its suitability for IoT systems. Our experimental results verify the effectiveness of the proposed method in terms of robustness, execution time, and security compared to other image encryption algorithms. Furthermore, our framework can reduce the bandwidth, storage, transmission cost, and the time required for analysts to browse large volumes of surveillance data and make decisions about abnormal events, such as suspicious activity detection and fire detection in surveillance applications.

Cobalt-free nickel rich layered oxide cathodes for lithium-ion batteries.

Abstract: We propose a feasibility of Co-free Ni-rich Li(Ni1–xMnx)O2 layer compound. Li(Ni1–xMnx)O2 (0.1 ≤ x ≤ 0.5) have been synthesized by a coprecipitation method. Rietveld refinement of X-ray diffraction and microscopic studies reveal dense and spherical secondary particles of highly crystalline phase with low cation mixing over the whole compositions, implying successful optimization of synthetic conditions. Electrochemical test results indicated that the Co-free materials delivered high capacity with excellent capacity retention and reasonable rate capability. In particular, Li(Ni0.9Mn0.1)O2, which possesses the lowest cation mixing in the Li layers among samples, exhibited exceptionally high rate capacity (approximately 149 mAh g–1 at 10 C rate) at 25 °C and high discharge capacity upon cycling under a severe condition, in the voltage range of 2.7–4.5 V at 55 °C. The cation mixing in Li(Ni0.9Mn0.1)O2 increased slightly even after the extensive cycling at the elevated temperature, which is ascribed to the str...