Suggestion of Maintenance Criteria for Electric Railroad Facilities Based on Fuzzy TOPSIS

This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly aging.To solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system maintenance.Also,maintenance items must be selected in a scientific and systematic method.Therefore,railroad electrical facility systems are selected for study.Design StructureMatrix(DSM)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making problem.Studies show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.

Delivery Invoice Information Classification System for Joint Courier Logistics Infrastructure

With the growth of the online market,demand for logistics and courier cargo is increasing rapidly.Accordingly,in the case of urban areas,road congestion and environmental problems due to cargo vehicles are mainly occurring.The joint courier logistics system,a plan to solve this problem,aims to establish an efficient logistics transportation system by utilizing one joint logistics delivery terminal by several logistics and delivery companies.However,several courier companies use different types of courier invoices.Such a system has a problem of information data transmission interruption.Therefore,the data processing process was systematically analyzed,a practically feasible methodology was devised,and delivery invoice information processing standards were established for this.In addition,the importance of this paper can be emphasized in terms of data processing in the logistics sector,which is expected to grow rapidly in the future.The results of this study can be used as basic data for the implementation of the logistics joint delivery terminal system in the future.And it can be used as a basis for securing the operational reliability of the joint courier logistics system.

Object Detection for Cargo Unloading System Based on Fuzzy C Means

With the recent increase in the utilization of logistics and courier services,it is time for research on logistics systems fused with the fourth industry sector.Algorithm studies related to object recognition have been actively conducted in convergence with the emerging artificial intelligence field,but so far,algorithms suitable for automatic unloading devices that need to identify a number of unstructured cargoes require further development.In this study,the object recognition algorithm of the automatic loading device for cargo was selected as the subject of the study,and a cargo object recognition algorithm applicable to the automatic loading device is proposed to improve the amorphous cargo identification performance.The fuzzy convergence algorithm is an algorithm that applies Fuzzy C Means to existing algorithm forms that fuse YOLO(You Only Look Once)and Mask R-CNN(Regions with Convolutional Neuron Networks).Experiments conducted using the fuzzy convergence algorithm showed an average of 33 FPS(Frames Per Second)and a recognition rate of 95%.In addition,there were significant improvements in the range of actual box recognition.The results of this study can contribute to improving the performance of identifying amorphous cargoes in automatic loading devices.

Origin of the giant persistent photoconductivity in LaAlO_(3)/SrTiO_(3)heterostructures probed by noise spectroscopy

LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room temperature.The abnormally strong PPC has attracted immense research interest due to its possible applications in optically-tunable electronic devices.Despite its promise,the fundamental understanding of the PPC in the LAO/STO heterostructures is still elusive.Herein,we report that the giant PPC origi-nates from the photo-induced valence change in oxygen vacancies near the LAO/STO interface.Our spec-tral analysis of the photocurrent and the model-fitting study consistently show that the ionized oxygen vacancies near the interface are neutralized during the electron relaxation process.They hinder the complete relaxation of the photoexcited electrons by the deeply-located oxygen vacancies and result in the strong PPC.The change in the ionization state distribution of the oxygen vacancies is probed by the per-sistent noise behavior at the frequency between 1 kHz and 20 kHz regime.These results provide insight into the role of oxygen vacancies in influencing the internal charge distribution and triggering the PPC phenomena in complex oxide heterostructures.

Voxelated opto-physically unclonable functions via irreplicable wrinkles

The increased prevalence of the Internet of Things(IoT)and the integration of digital technology into our daily lives have given rise to heightened security risks and the need for more robust security measures.In response to these challenges,physical unclonable functions(PUFs)have emerged as promising solution,offering a highly secure method to generate unpredictable and unique random digital values by leveraging inherent physical characteristics.However,traditional PUFs implementations often require complex hardware and circuitry,which can add to the cost and complexity of the system.We present a novel approach using a random wrinkles PUF(rw-PUF)based on an optically anisotropic,facile,simple,and cost-effective material.These wrinkles contain randomly oriented liquid crystal molecules,resulting in a two-dimensional retardation map corresponding to a complex birefringence pattern.Additionally,our proposed technique allows for customization based on specific requirements using a spatial light modulator,enabling fast fabrication.The random wrinkles PUF has the capability to store multiple data sets within a single PUF without the need for physical alterations.Furthermore,we introduce a concept called‘polyhedron authentication,’which utilizes three-dimensional information storage in a voxelated random wrinkles PUF.This approach demonstrates the feasibility of implementing high-level security technology by leveraging the unique properties of the rw-PUF.

Optically pumped low-threshold microdisk lasers on a GeSn-on-insulator substrate with reduced defect density

Despite the recent success of GeSn infrared lasers,the high lasing threshold currently limits their integration into practical applications.While structural defects in epitaxial GeSn layers have been identified as one of the major bottlenecks towards low-threshold GeSn lasers,the effect of defects on the lasing threshold has not been well studied yet.Herein,we experimentally demonstrate that the reduced defect density in a GeSn-on-insulator substrate improves the lasing threshold significantly.We first present a method of obtaining high-quality GeSn-oninsulator layers using low-temperature direct bonding and chemical–mechanical polishing.Low-temperature photoluminescence measurements reveal that the reduced defect density in GeSn-on-insulator leads to enhanced spontaneous emission and a reduced lasing threshold by0 times andtimes,respectively.Our result presents a new path towards pushing the performance of GeSn lasers to the limit.