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Cellulose-Based Nanocomposite Insulation Material with Excellent Thermal Aging Resistance: KH550-hBN-Modified Cellulose Insulation Paper

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IEEE Transactions on Dielectrics and Electrical Insulation 2025年

作者： Wang, Zuhao Peng, Xiao Chronis, Ioannis Wu, Yingrui Psomopoulos, Constantinos S. Tang, Chao Southwest University College of Engineering and Technology International R & D Center for New Technologies of Smart Grid and Equipment Chongqing400715 China Southwest University College of Engineering and Technology Chongqing400715 China Chongqing University State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing400044 China University of West Attica High Voltage and Energy Systems Research Lab Dept. of Electrical and Electronics Engineering EgaleoGR-122 44 Greece

As the global power industry evolves, transformer insulation systems face increasing challenges. The aging of cellulose insulation paper (cellulose-IP) at elevated temperatures significantly impacts its insulation properties and overall lifespan. To enhance the thermal aging resistance and industrial usability of cellulose-IP, this study employs nano-boron nitride (h-BN) along with three silane coupling agents - 3-ammonopropyltriethoxysilane (KH550), 3-glycidyloxypropyltrimethoxysilane (KH560), and 3-methacryloyloxypropyltrimethoxysilane (KH570) - to modified cellulose-IP. Upon evaluating the properties and simulation results of the modified cellulose-IP, KH550-hBN demonstrated superior properties and was selected for an accelerated thermal aging test lasting 60 days. The results indicated that KH550-hBN effectively mitigates the degradation of cellulose-IP. In the late aging stage, the mechanical properties of the modified cellulose-IP deteriorated more slowly than those of pure cellulose-IP. Additionally, thermal conductivity improved by 26.9%, while breakdown field strength increased by 12.1%. The introduction of KH550-hBN promotes the formation of a complete thermal conductivity network within the cellulose matrix, increases the number of intermolecular hydrogen bonds and introduces nano-barrier regions. These improvements enhance the interactions between the cellulose systems and effectively inhibit the generation and migration of polar derivatives during the aging process, resulting in a significant improvement in the longevity and stability of transformer internal insulation systems. © 1994-2012 IEEE.

关键词： Boron nitride

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Seismic retrofit of structures using friction dampers

Journal of Dynamic Disasters

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Journal of Dynamic Disasters 2025年第2期1卷

作者： Yun Joo Lee Akbar Sajjad Jinkoo Kim Civil Architectural and Environmental System Engineering Sungkyunkwan University South Korea Dept. of Global Smart City Sungkyunkwan University South Korea

This study investigates the feasibility and applicability of spring-friction dampers for seismic retrofit of structures. Finite element analysis of the device was carried out to verify the relationship between the bolt pretension force and the friction yield force. Parametric study of the device was conducted to investigate the effect of the recovery force provided by the coil spring. The developed damper was applied to a five-story reinforced concrete (RC) framed building to assess its efficacy for seismic retrofit. The seismic performance of the device was thoroughly evaluated, focusing on its ability to reduce inter-story and residual displacements by dissipating seismic energy and providing stiffness and recovery force. The particle swarm optimization algorithm was applied to find out the optimum number of dampers and their optimum locations. The results demonstrate that the proposed damper and the optimum design scheme can be effectively utilized to protect structures against seismic loads.

关键词： Friction dampers Seismic retrofit Earthquakes Particle swarm optimization

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LSTM based hydraulic excavator angular velocity prediction model

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Journal of Institute of Control, robotics and systems 2019年第8期25卷 705-712页

作者： Ryu, Bo-Hyun Han, Chang-Soo Dept. of Plant Engineering System Engineering Team Institute for Advanced Engineering Korea Republic of Dept. of Mechatronics. Eng. Hanyang University Korea Republic of Dept. of Robot Eng. Hanyang University Korea Republic of

This paper proposes a long short-term memory (LSTM) model for predicting the angular velocity of an excavator. An excavator’s movement command appears at the speed of its hydraulic cylinder, which then appears as the angular velocity of its joint. Therefore, if the angular velocity of the joint, which changes as a function of the operating command, can be predicted, the excavator can be controlled. However, since the cylinder is a nonlinear system, it is difficult to create a system model. To solve this problem, we propose a model having long short-term memory (LSTM) based angular velocity prediction. We constructed an experimental environment for a hydraulic RC excavator, collected excavator data, and analyzed the prediction accuracy of our LSTM model. In addition, we applied the LSTM-based angular velocity prediction model to a PID control algorithm to compare the general PID control algorithm with the proposed control performance. © ICROS 2019.

关键词： Excavators

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An implement of condition monitoring system for a tensioning device based on IoT in electric Railway

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Transactions of the Korean Institute of Electrical Engineers 2019年第8期68卷 1025-1031页

作者： Lee, Kiwon Na, Kyung-Min Park, Young Cho, Ho-Ryung D2 Engineering Korea Republic of Smart Electric and Signaling Division Korea Railroad Research Institute Korea Republic of Dept. of Electrical System Engineering Hanbat Univerity Korea Republic of Dept. of Transportation System Engineering University of Science and Technology Korea Republic of

The contact wire made of copper or copper alloy is installed to keep a good current collection performance between a pantograph and catenary system. The tensioning device installed in a contact and messenger wire is required to have high reliability as a major component of the feeding facility which keeps constant tension of the wires regardless of temperature changes. The maintenance of the tensioning device is generally performed by the man power. In this paper, we propose a condition monitoring system for a spring tension device using sensor network and communication based on Internet of Thing. The proposed monitoring system is composed of a structure integrated with tensioning device by applying an ultrasonic sensor with minimum power consumption and communication device. It was able to monitor the dynamic state of the tensioning device according to temperature change n real time through the displacement of ultrasonic sensor. Copyright © The Korean Institute of Electrical Engineers

关键词： Condition monitoring

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Automatic Extraction of Bridge Dimensional Information Using 3D Point Cloud Data

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KSCE Journal of Civil engineering 2025年

作者： Jehee Han Minseo Jang Hyungseo Han Do Hyoung Shin Dept. of Smart City Engineering Inha University Incheon 22212 South Korea. Research Institute of Construction & Environmental System Inha University Incheon 22212 South Korea. Dept. of Civil Engineering Inha University Incheon 22212 South Korea.

The advent of advanced 3D LiDAR technology and progress in computer vision have led to the extensive utilization of three-Dimensional Point Cloud Data (3D PCD) across various fields such as robotics and autonomous driving, as well as in the construction industry. Particularly, for infrastructure facilities lacking design drawings or with missing records, automated Scan-to-BIM technology plays a pivotal role in efficiently generating three-dimensional models. However, while recent studies have actively explored the segmentation of 3D PCD essential for automated Scan-to-BIM technologies in infrastructure, subsequent research, such as deriving dimensions of segmented objects, remains relatively underdeveloped. This study proposes a novel method for automatically extracting dimensional information for each component of a bridge using 3D PCD. Unlike existing methods that rely solely on the intrinsic characteristics of 3D LiDAR to derive lengths, the proposed approach is capable of handling challenges such as sloped superstructures and multiple piers with varying lengths. The proposed method combines RANSAC, geometric features, edge detection, and orthographic projection techniques to accurately and automatically extract dimensional information from 3D PCD. This approach not only provides critical data for generating bridge BIM models but also holds potential for quickly predicting damages such as deflections and deformations in bridges.

关键词： 3D Point Cloud Data Automated Scan to BIM RANSAC Construction Management

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The Impact of Greening Strategies on Temperature Reduction at Bus Stop Utilizing Computational Fluid Dynamics (Cfd) Analysis

SSRN

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SSRN 2024年

作者： Kim, Na Youn Kim, Eun Sub Yun, Seokhwan Lee, Dong Kun Department of Landscape Architecture and Rural System Engineering Seoul National University Seoul08826 Korea Republic of Interdisciplinary Program in Landscape Architecture Seoul National University Seoul08826 Korea Republic of Integrated Major in Smart City Global Convergence Program Seoul National University Seoul08826 Korea Republic of Specialized Graduate School of Intelligent Eco-Science 4 Dept. of Landscape Architecture Seoul National University Seoul08826 Korea Republic of

This study analyzed the effectiveness of a vegetation strategy for mitigating heat within a bus stop shelter by implementing vegetation wind permeability and transpiration cooling processes using a computational fluid dynamics (CFD) simulation. In scenario 1, a pot-type vertical greening system (VGS) without wind permeability had no significant effect on temperature reduction in the bus stop shelter. In contrast, scenario 2, with a mesh VGS allowing wind permeability, resulted in an average temperature reduction of 0.16°C within the interior area of the bus stop shelter, accompanied by shelter improved ventilation. Scenario 3, which entailed the removal of the shelter and the planting of trees, resulted in the least reduction in wind speed and an average temperature reduction of 0.14°C in the bus waiting area. Scenario 2 demonstrated the most effective temperature reduction for interior and surrounding area of the bus stop. Considering the normal effective temperature (NET), Scenario 3 provided the lowest sensation temperature. This indicates that the improved ventilation in Scenario 3 had a substantial impact on NET. Considering the effects of the vegetation strategies proposed in this study, it is essential to select suitable strategies for heat mitigation in bus-stop shelters based on regional and spatial considerations. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Autonomous flying of drone based on ppo reinforcement learning algorithm

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Journal of Institute of Control, robotics and systems 2020年第11期26卷 955-963页

作者： Park, Sung Gwan Kim, Dong Hwan Dept. of Mechanical Design and Robot Engineering Seoul National University of Science and Technology Korea Republic of Dept. of Mechanical System Design Engineering Seoul National University of Science and Technology Korea Republic of

In this study, the performance of autonomous flight was analyzed by introducing the PPO method as reinforcement learning for autonomous flight of drones. A simulator based on the dynamics of a drone was produced, and the performance of autonomous flight was confirmed when reinforcement learning was applied to a drone using this simulator. After that, the possibility of autonomous flight was confirmed by applying the PPO algorithm to the actual drone. Also, a lightweight embedded PC was attached to the drone to perform independent calculations to simultaneously construct obstacle avoidance and path planning. Copyright© ICROS 2020.

关键词： Simulators

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Spatial single mode laser source interaction with measured pulse based parabolic index multimode fiber

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Journal of Optical Communications 2024年第0期45卷 s465-s473页

作者： Rashed, Ahmed Nabih Zaki Ahammad, S.K. Hasane Daher, Malek G. Sorathiya, Vishal Siddique, Abrar Asaduzzaman, Sayed Rehana, Hasin Dutta, Nitul Patel, Shobhit K. Nyangaresi, Vincent Omollo Jibon, Rayhan Habib Abdelhamid, Huda Said Electronics and Electrical Communications Engineering Department Faculty of Electronic Engineering Menoufia University Menouf32951 Egypt Department of ECE Koneru Lakshmaiah Education Foundation Andhra Pradesh Vaddeswaram522302 India Physics Department Islamic University of Gaza P.O. Box 108 Gaza Palestine Department of Information and Communication Technology Marwadi University Rajkot India Department of Smart Robot Convergence and Application Engineering Pukyong National University Busan48513 Korea Republic of Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Department of Computer Science and Engineering Rangamati Science and Technology University Rangamati Bangladesh Department of Computer Science and Engineering Daffodil International University Dhaka Bangladesh Computer Sc and Engg. Dept. SRM University Andhra Pradesh Guntur India Electronics and Communication Engg. Department Marwadi University Gujarat Rajkot India Tom Mboya University College P.O. Box 199-40300 Homabay Kenya Electronics and Communication Engineering Discipline Khulna University Khulna9208 Bangladesh

The study clarified spatial single mode laser interaction with measured pulse based parabolic index multimode fiber. Peak power level margin, maximum/minimum signal amplitude margin after parabolic index multimode fiber are measured with core radius of 25 μm, cladding thickness of 10 μm, refractive index peak of 1.4142, length of 300 m, and refractive index step of 1%. Maximum signal power margin against spectral frequency after PIN light detector based parabolic fiber properties is tested under the same operating parameters. The signal power amplitude/power within parabolic index multimode fiber is also measured based on variations of fiber lengths and relative refractive index step. The study implies the multimode graded index fibers with parabolic or near parabolic index profile cores have transmission bandwidths than other multimode fibers. © 2022 Walter de Gruyter GmbH, Berlin/Boston.

关键词： Multimode fibers

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Modeling Supports the Implementation of Urban Greening as a Response to the Challenges of Sustainable Spatial Planning

SSRN

引用

SSRN 2024年

作者： Kim, Eun Sub Lee, Dong Kun Hyun, Jung Hee Kim, Na Yeon Heo, Su Jeong Kim, Da Sle Interdisciplinary Program in Landscape Architecture Seoul National University Seoul08826 Korea Republic of Integrated Major in Smart City Global Convergence Program Seoul National University Seoul08826 Korea Republic of Specialized Graduate School of Intelligent Eco-Science 4 Dept. of Landscape Architecture Seoul National University Seoul08826 Korea Republic of Systemic Risk and Resilience Research Group Advancing Systems Analysis International Institute for Applied Systems Analysis Austria Department of Landscape Architecture and Rural System Engineering Seoul National University Seoul08826 Korea Republic of

Urban greening is a critical strategy for sustainable urban development, climate change mitigation, and biodiversity conservation. However, the effectiveness of urban greening varies depending on the specific goals (e.g., enhancing biodiversity, reducing urban heat, or both) and their spatial implementation. To address the spatial variability in the effectiveness of greening, we propose a spatial decision support model based on the non-dominated sorting genetic algorithm-II (NSGA-II). This model aims to optimize urban greening locations to maximize biomass density, mitigate urban heat stress, and simultaneously improve landscape connectivity. Applied to Suwon City, South Korea, the model's effectiveness was evaluated against a Business-As-Usual (BAU) scenario across four scenarios: Connectivity-based, Biomass density-based, Heat stress-based, and an Integrated-based scenario. The integrated approach, balancing trade-offs between ecological benefits and implementation costs, outperformed the BAU scenario by 8.84%. This outcome indicated of significant improvements in biomass density and landscape connectivity, despite highlighting a weaker correlation with heat stress mitigation. Our findings underscore the necessity of an integrated planning approach to urban greening, as it can contribute toward the attainment of urban development goals. Additionally, by proposing an app-based model for policymakers to utilize, our outputs should enable the reconciliation of multiple environmental objectives in urban landscapes. © 2024, The Authors. All rights reserved.

关键词： Climate change

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An implementation of calibration system for arc detection in 220 nm UV light

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Transactions of the Korean Institute of Electrical Engineers 2020年第10期69卷 1490-1494页

作者： Na, Kyung-Min Lee, Kiwon Park, Chul-Min Park, Young Dept. of Electrical System Engineering Hanbat National University Korea Republic of Dept. of Transportation Engineering Korea University of Science and Technology Korea Republic of Smart Electrical and Signaling Division Korea Railroad Research Institute Korea Republic of

The demand for renewable energy equipment and power equipment for use in electric railways has been increasing owing to the expansion of dispersed power sources and urban railroads. Arc flashes occur because of insulation breakdown, leakage, and contact loss, and it may cause electric fires in DC power equipment. Arc flashes are detected by temperature, pressure, acoustic, light, and electrical methods. The photosensor detection is a noncontact method but has the disadvantage of high external noise owing to sunlight depending on the wavelength band from among these. An arc detector in the 220-nm ultraviolet (UV) light is developed to reduce noise and is not affected by sunlight. However, there is no prior research on the deterioration of electrical equipment when using arc discharge. Therefore, correcting errors, such as light density, generation time, and distance, through arc flash replay is necessary to determine the deterioration of DC power equipment. In this paper, we propose a calibration system for reproducing an arc flash in the 220-nm UV light. The calibration system comprises a 150-W light source and a xenon-series chopper disc, and the result of the photosensor response to 220-nm UV light is noted. Copyright © The Korean Institute of Electrical Engineers

关键词： Deterioration

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