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Low Phase Noise VCO using Novel Harmonic Control Circuit Based on Quad-band Composite Right/Left-handed Transmission Line

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Journal of Measurement Science and Instrumentation 2010年第4期1卷 380-386页

作者： Jae-won CHOI chul-hun seo School of Electronic Engineering Soongsil University

In this paper, a novel Voltage-Controlled Oscillator （VCO） using the harmonic control circuit based on the quad-band Composite Right/Left-Handed （CRLH） Transmission Line （TL） is presented to reduce the phase noise without the reduction of the frequeacy tuning range and miniaturizing the circuit size. The phase noise has been reduced by the quad-band harmonic control circuit which has the short impedance for the second- and third- and fourth- and fifth-hannonic components. The CRLH TL with two Left-Handed （LH）（backward） and two Right-Handed （RH）（forward） pass bands are used to design the quad-band harmonic control circuit. The high- Q resonator has been used to reduce the phase noise, but it has the problem of the frequency timing range reduction. However, the frequency tuning range of the proposed VCO has not reduced because the phase noise has reduced without the high-Q resonator. The miniaturization of the circuit size is achieved by using the quad-band CRLH TL instead of the conventional RH TL, The phase noise of VCO is - 124.43～ - 122.67 dBc/Hz at 100 kHz in the tuning range of 5. 729 ～5.934 GHz.

关键词： VCO phase noise frequency tuning range miniaturization novel harmonic control circuit quad-band CRLH TLs

Generating synthetic as-built additive manufacturing surface topography using progressive growing generative adversarial networks

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Friction 2024年第6期12卷 1283-1298页

作者： Junhyeon seo Prahalada RAO Bart RAEYMAEKERS Department of Mechanical Engineering Virginia TechBlacksburgVA 24061USA Grado Department of Industrial and Systems Engineering Virginia TechBlacksburgVA 24061USA

Numerically generating synthetic surface topography that closely resembles the features and characteristics of experimental surface topography measurements reduces the need to perform these intricate and costly ***,existing algorithms to numerically generated surface topography are not well-suited to create the specific characteristics and geometric features of as-built surfaces that result from laser powder bed fusion(LPBF),such as partially melted metal particles,porosity,laser scan lines,and ***,we present a method to generate synthetic as-built LPBF surface topography maps using a progressively growing generative adversarial *** qualitatively and quantitatively demonstrate good agreement between synthetic and experimental as-built LPBF surface topography maps using areal and deterministic surface topography parameters,radially averaged power spectral density,and material ratio *** ability to accurately generate synthetic as-built LPBF surface topography maps reduces the experimental burden of performing a large number of surface topography ***,it facilitates combining experimental measurements with synthetic surface topography maps to create large data-sets that facilitate,*** as-built surface topography to LPBF process parameters,or implementing digital surface twins to monitor complex end-use LPBF parts,amongst other applications.

关键词： additive manufacturing surface topography synthetic surface topography generative adversarial networks

MXenes: Versatile 2D materials with tailored surface chemistry and diverse applications

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Journal of Energy Chemistry 2024年第3期90卷 253-293,I0008页

作者： Sunil Kumar Nitu Kumari Yongho seo Department of Nanotechnology and Advanced Materials Engineering and HMC Sejong UniversitySeoul 05006South Korea School of Studies in Chemistry Jiwaji UniversityGwalior 474011India

MXenes,the most recent addition to the 2D material family,have attracted significant attention owing to their distinctive characteristics,including high surface area,conductivity,surface characteristics,mechanical strength,*** review begins by presenting MXenes,providing insights into their structural characteristics,synthesis methods,and surface functional *** review covers a thorough analysis of MXene surface properties,including surface chemistry and termination group *** properties of MXenes are influenced by their synthesis,which can be fluorine-based or ***-based synthesis techniques involve etching with fluorine-based reagents,mainly including HF or LiF/HCl,while fluorine-free methods include electrochemical etching,chemical vapor deposition(CVD),alkaline etching,Lewis acid-based etching,*** techniques result in the emergence of functional groups such as-F,-O,-OH,-Cl,*** the MXenes surface,depending on the synthesis method *** of MXenes,such as electrical conductivity,electronic properties,catalytic activity,magnetic properties,mechanical strength,and chemical and thermal stability,are examined,and the role of functional groups in determining these properties is *** review delves into the diverse applications of MXenes,encompassing supercapacitors,battery materials,hydrogen storage,fuel cells,electromagnetic interference(EMI) shielding,pollutant removal,water purification,flexible electronics,sensors,additive manufacturing,catalysis,biomedical and healthcare fields,***,this article outlines the challenges and opportunities in the current and future development of MXenes research,addressing various aspects such as synthesis scalability,etching challenges,and multifunctionality,and exploring novel *** review concludes with future prospects and conclusions envisioning the impact of MXenes on future technologies and innovation.

关键词： MXenes 2D materials Surface chemistry MXenes structure Synthesis Applications

A Cu-Pd alloy catalyst with partial phase separation for the electrochemical CO_(2) reduction reaction

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Journal of Energy Chemistry 2024年第6期93卷 8-15,I0001页

作者： Gyeong Ho Han Jung Yong seo Minji Kang Myung-gi seo Youngheon Choi Soo Young Kim Sang Hyun Ahn School of Chemical Engineering and Material Science Chung-Ang UniversitySeoul 06974Republic of Korea Lotte Chemical Institute of Technology Daejeon 34110Republic of Korea Department of Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea

Cu catalysts can convert CO_(2) through an electrochemical reduction reaction into a variety of useful carbon-based ***,this capability provides an obstacle to increasing the selectivity for a single ***,we report a simple fabrication method for a Cu-Pd alloy catalyst for use in a membrane electrode assembly(MEA)-based CO_(2) electrolyzer for the electrochemical CO_(2) reduction reaction(ECRR)with high selectivity for CO *** the composition of the Cu-Pd alloy catalyst was fabricated at 6:4,the selectivity for CO increased and the production of multi-carbon compounds and hydrogen is *** a Cu-Pd alloy catalyst with 6:4 ratio as the cathode of the MEAbased CO_(2) electrolyzer showed a CO faradaic efficiency of 92.8%at 2.4 V_(cell).We assumed that these results contributed from the crystal planes on the surface of the Cu-Pd *** phases of the Cu-Pd alloy catalyst were partially separated through annealing to fabricate a catalyst with high selectivity for CO at low voltage and C_(2)H_4 at high *** results of CO-stripping testing confirmed that when Cu partially separates from the lattice of the Cu-Pd alloy,the desorption of~*CO is suppressed,suggesting that C-C coupling reaction is favored.

关键词： Cu-Pd catalyst Electrodeposition Electrochemical carbon dioxide reduction Partial phase separation Membrane electrode assembly-based electrolyzer

Few-Shot Graph Classification with Structural-Enhanced Contrastive Learning for Graph Data Copyright Protection

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Tsinghua Science and Technology 2024年第2期29卷 605-616页

作者： Kainan Zhang DongMyung Shin Daehee seo Zhipeng Cai Department of Computer Science Georgia State UniversityAtlantaGA 30303USA LSWare Inc. Seoul 08504Republic of Korea College of Intelligence Information Engineering Sangmyung UniversitySeoul 03016Republic of Korea

Open-source licenses can promote the development of machine learning by allowing others to access,modify,and redistribute the training ***,not all open-source licenses may be appropriate for data sharing,as some may not provide adequate protections for sensitive or personal information such as social network ***,some data may be subject to legal or regulatory restrictions that limit its sharing,regardless of the licensing model ***,obtaining large amounts of labeled data can be difficult,time-consuming,or expensive in many real-world ***-shot graph classification,as one application of meta-learning in supervised graph learning,aims to classify unseen graph types by only using a small amount of labeled ***,the current graph neural network methods lack full usage of graph structures on molecular graphs and social network *** structural features are known to correlate with molecular properties in chemistry,structure information tends to be ignored with sufficient property information ***,the common binary classification task of chemical compounds is unsuitable in the few-shot setting requiring novel ***,this paper focuses on the graph classification tasks of a social network,whose complex topology has an uncertain relationship with its nodes'*** two multi-class graph datasets with large node-attribute dimensions constructed to facilitate the research,we propose a novel learning framework that integrates both meta-learning and contrastive learning to enhance the utilization of graph topological *** experiments demonstrate the competitive performance of our framework respective to other state-of-the-art methods.

关键词： few-shot learning contrastive learning data copyright protection

Organic X-Ray Image Sensors Using a Medium Bandgap Polymer Donor with Low Dark Current

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 230-237页

作者： Ha, Jong-Woon Eom, Seung hun Cha, Bo Kyung Song, Seyeong Eun, Hyeong Ju Kim, Jong H. Park, Jong Mok Kim, Bongsoo Park, Byoungwook Ko, seo-Jin Yoon, Sung Cheol Lee, Changjin Jung, In Hwan Hwang, Do-Hoon Pusan Natl Univ Chem Inst Funct Mat Dept Chem Busan 46241 South Korea Korea Res Inst Chem Technol KRICT Div Adv Energy Mat Res Ctr Daejeon 34114 South Korea Korea Electrotechnol Res Inst KERI Electromed Device Res Ctr Ansan 15588 South Korea Ulsan Natl Inst Sci & Technol UNIST Grad Sch Carbon Neutral Sch Energy & Chem Engn Ulsan 44919 South Korea Ajou Univ Dept Mol Sci & Technol Suwon 16449 South Korea Korea Res Inst Chem Technol Res Ctr Adv Specialty Chem Ulsan 44412 South Korea Ulsan Natl Inst Sci & Technol UNIST Dept Chem Ulsan 44919 South Korea Hanyang Univ Dept Organ & Nano Engn Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea

The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations. However, this is quite challenging because of the heavy weight of the scintillator and silicon photodetectors. The weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic photodetectors. This study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer (similar to 700 nm), owing to the symmetric backbone and highly soluble molecular structure of bithienopyrroledione. The ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density (J(d) similar to 10(-10) A cm(-2)) at a negative bias (-2.0 V) while maintaining high responsivity (R = 0.29 A W-1) even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D-sh* = 2.18 x 10(13) Jones in the organic photodetectors. Printed organic photodetectors are developed by slot-die coating for use in X-ray detectors, which exhibit D-sh* = 2.73 x 10(12) Jones with clear rising (0.26 s) and falling (0.29 s) response times upon X-ray irradiation. Detection reliability is also proven by linear response of the X-ray detector, and the X-ray detection limit is 3 mA.

关键词： low dark current low detection limit organic photodetector printable X-ray DETECTORS PHOTOCONDUCTORS SENSITIVITY

A Comprehensive Survey on Federated Learning in the Healthcare Area: Concept and Applications

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2239-2274页

作者： Deepak Upreti Eunmok Yang Hyunil Kim Changho seo Department of Convergence Science Kongju National UniversityChungcheongnam-doGongju-si32588South Korea Department of Information Security Cryptologyand MathematicsKookmin UniversitySeoul02707South Korea Department of Information and Communication Engineering Chosun UniversityGwangju61452South Korea Basic Science Research Institution Kongju National UniversityChungcheongnam-doGongju-si32588South Korea

Federated learning is an innovative machine learning technique that deals with centralized data storage issues while maintaining privacy and *** involves constructing machine learning models using datasets spread across several data centers,including medical facilities,clinical research facilities,Internet of Things devices,and even mobile *** main goal of federated learning is to improve robust models that benefit from the collective knowledge of these disparate datasets without centralizing sensitive information,reducing the risk of data loss,privacy breaches,or data *** application of federated learning in the healthcare industry holds significant promise due to the wealth of data generated from various sources,such as patient records,medical imaging,wearable devices,and clinical research *** research conducts a systematic evaluation and highlights essential issues for the selection and implementation of federated learning approaches in *** evaluates the effectiveness of federated learning strategies in the field of *** offers a systematic analysis of federated learning in the healthcare domain,encompassing the evaluation metrics *** addition,this study highlights the increasing interest in federated learning applications in healthcare among scholars and provides foundations for further studies.

关键词： Federated learning artificial intelligence machine learning privacy healthcare

Lightweight Super-Resolution Model for Complete Model Copyright Protection

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Tsinghua Science and Technology 2024年第4期29卷 1194-1205页

作者： Bingyi Xie Honghui Xu YongJoon Joe Daehee seo Zhipeng Cai Department of Computer Science Georgia State UniversityAtlantaGA 30303USA LSWare Inc. Seoul 08504Republic of Korea College of Intelligence Information Engineering Sangmyung UniversityRepublic of KoreaSeoul 03016

Deep learning based techniques are broadly used in various applications, which exhibit superior performance compared to traditional methods. One of the mainstream topics in computer vision is the image super-resolution task. In recent deep learning neural networks, the number of parameters in each convolution layer has increased along with more layers and feature maps, resulting in better image super-resolution performance. In today’s era, numerous service providers offer super-resolution services to users, providing them with remarkable convenience. However, the availability of open-source super-resolution services exposes service providers to the risk of copyright infringement, as the complete model could be vulnerable to leakage. Therefore, safeguarding the copyright of the complete model is a non-trivial concern. To tackle this issue, this paper presents a lightweight model as a substitute for the original complete model in image super-resolution. This research has identified smaller networks that can deliver impressive performance, while protecting the original model’s copyright. Finally, comprehensive experiments are conducted on multiple datasets to demonstrate the superiority of the proposed approach in generating super-resolution images even using lightweight neural networks.

关键词： lightweight adversarial learning image super-resolution copyright protection

Caching Strategies in NDN Based Wireless Ad Hoc Network:A Survey

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Computers, Materials & Continua 2024年第7期80卷 61-103页

作者： Ahmed Khalid Rana Asif Rehman Byung-seo Kim Department of Computer Science FAST School of ComputingNational University of Computer and Emerging SciencesLahore54000Pakistan Department of Software and Communications Engineering Hongik UniversitySejong City30016Republic of Korea

Wireless Ad Hoc Networks consist of devices that are wirelessly *** Ad Hoc Networks(MANETs),Internet of Things(IoT),and Vehicular Ad Hoc Networks(VANETs)are the main domains of wireless ad hoc *** is used in wireless ad hoc *** is based on Transmission Control Protocol(TCP)/Internet Protocol(IP)network where clients and servers interact with each other with the help of IP in a pre-defined *** fetches data from a fixed *** redundancy,mobility,and location dependency are the main issues of the IP network *** these factors result in poor performance of wireless ad hoc *** main disadvantage of IP is that,it does not provide in-network ***,there is a need to move towards a new network that overcomes these *** Data Network(NDN)is a network that overcomes these *** is a project of Information-centric Network(ICN).NDN provides in-network caching which helps in fast response to user *** NDN in wireless ad hoc network provides many benefits such as caching,mobility,scalability,security,and *** considering the certainty,in this survey paper,we present a comprehensive survey on Caching Strategies in NDN-based Wireless *** cachingmechanism-based results are also *** the last,we also shed light on the challenges and future directions of this promising field to provide a clear understanding of what caching-related problems exist in NDN-based wireless ad hoc networks.

关键词： Content centric network Internet of Things mobile ad hoc network named data network vehicular ad hoc network