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Two-Terminal Lithium-Mediated Artificial Synapses with Enhanced Weight Modulation for Feasible Hardware Neural Networks

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Nano-Micro Letters 2023年第5期15卷 236-253页

作者： Ji hyun Baek Kyung Ju Kwak Seung Ju Kim Jaehyun Kim Jae Young Kim In Hyuk Im Sunyoung lee Kisuk kang Ho Won Jang Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Republic of Korea Advanced Institute of Convergence Technology Seoul National UniversitySuwon 16229Korea

Recently,artificial synapses involving an electrochemical reaction of Li-ion have been attributed to have remarkable synaptic ***-terminal synaptic transistors utilizing Li-ion intercalation exhibits reliable synaptic characteristics by exploiting the advantage of nondistributed weight updates owing to stable ion ***,the three-terminal configurations with large and complex structures impede the crossbar array implementation required for hardware neuromorphic ***,achieving adequate synaptic performances through effective Li-ion intercalation in vertical two-terminal synaptic devices for array integration remains ***,two-terminal Au/LixCoO_(2)/Pt artificial synapses are proposed with the potential for practical implementation of hardware neural *** Au/LixCoO_(2)/Pt devices demonstrated extraordinary neuromorphic behaviors based on a progressive dearth of Li in LixCoO_(2)*** intercalation and deintercalation of Li-ion inside the films are precisely controlled over the weight control spike,resulting in improved weight control *** types of synaptic plasticity were imitated and assessed in terms of key factors such as nonlinearity,symmetricity,and dynamic ***,the LixCoO_(2)-based neuromorphic system outperformed three-terminal synaptic transistors in simulations of convolutional neural networks and multilayer perceptrons due to the high linearity and low programming *** impressive performances suggest the vertical two-terminal Au/LixCoO_(2)/Pt artificial synapses as promising candidates for hardware neural networks.

关键词： Artificial synapse Neuromorphic Li-based Two-terminal Synaptic plasticity

ESG Discourse Analysis Through BERTopic: Comparing News Articles and Academic Papers

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Computers, Materials & Continua 2023年第6期75卷 6023-6037页

作者： Haein lee Seon Hong lee Kyeo Re lee Jang hyun Kim Department of Applied Artificial Intelligence/Department of Human-Artificial Intelligence Interaction Sungkyunkwan UniversitySeoul03063Korea Center for SW Education Hanyang UniversityAnsan15588Korea Department of Interaction Science/Department of Human-Artificial Intelligence Interaction Sungkyunkwan UniversitySeoul03063Korea

Environmental,social,and governance(ESG)factors are critical in achieving sustainability in business management and are used as values aiming to enhance corporate ***,non-financial indicators have been considered as important for the actual valuation of corporations,thus analyzing natural language data related to ESG is *** previous studies limited their focus to specific countries or have not used big *** methodologies are insufficient for obtaining potential insights into the best practices to leverage *** address this problem,in this study,the authors used data from two platforms:LexisNexis,a platform that provides media monitoring,and Web of Science,a platform that provides scientific *** big data were analyzed by topic *** modeling can derive hidden semantic structures within the *** this process,it is possible to collect information on public and academic *** authors explored data from a text-mining perspective using bidirectional encoder representations from transformers topic(BERTopic)—a state-of-the-art topic-modeling *** addition,changes in subject patterns over time were considered using dynamic topic *** a result,concepts proposed in an international organization such as the United Nations(UN)have been discussed in academia,and the media have formed a variety of agendas.

关键词： ESG BERTopic natural language processing topic modeling

Thermal-environment characteristics and comfort of combined radiant-floor (Korean heating system ondol) and convective cooling system

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Journal of Central South University 2013年第12期20卷 3589-3603页

作者： lee kang-Guk HONG Won-Hwa School of Architecture Kyungpook National University

The thermal-environment characteristics of the existing forced-convection cooling system were compared with those of the convective cooling system, which combined the radiant-floor cooling system using floor-heating panel typically applied to apartments in South Korea with the forced-convection cooling system using improved fan coil unit. The subjective warm/cool-feeling responses to the combined radiant-floor and convective cooling system in the questionnaire survey conducted among the test subjects were analyzed to establish the basic data for the combined cooling system. The results show that in the thermal-equilibrium condition, the vertical air temperature difference in the model living room is larger in the forced-convection-cooling condition. Most of the subjects feel a proper warm/cool feeling on their entire body, but they feel colder on the foot and lower body in the combined-cooling condition.

关键词： convection cooling temperature ondol thermal comfort fan coil unit combined cooling system

Clustering Reference Images Based on Covisibility for Visual Localization

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Computers, Materials & Continua 2023年第5期75卷 2705-2725页

作者： Sangyun lee Junekoo kang hyunki Hong School of Integrative Engineering Chung-Ang UniversityHeukseok-ro 84Dongjak-kuSeoul06973Korea School of Software Chung-Ang UniversityHeukseok-ro 84Dongjak-kuSeoul06973Korea

In feature-based visual localization for small-scale scenes,local descriptors are used to estimate the camera pose of a query *** large and ambiguous environments,learning-based hierarchical networks that employ local as well as global descriptors to reduce the search space of database images into a smaller set of reference views have been ***,since global descriptors are generated using visual features,reference images with some of these features may be erroneously *** order to address this limitation,this paper proposes two clustering methods based on how often features appear as well as their *** both approaches,the scene is represented by voxels whose size and number are computed according to the size of the scene and the number of available *** the first approach,a voxel-based histogram representing highly reoccurring scene regions is generated from reference images.A meanshift is then employed to group the most highly reoccurring voxels into place clusters based on their spatial *** the second approach,a graph representing the covisibility-based relationship of voxels is *** matching is performed within the reference image clusters,and a perspective-n-point is employed to estimate the camera *** experimental results showed that camera pose estimation using the proposed approaches was more accurate than that of previous methods.

关键词： Visual localization deep learning voxel representation clustering covisibility meanshift graph structure

A metallic anti-biofouling surface with a hierarchical topography containing nanostructures on curved micro-riblets

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Microsystems & Nanoengineering 2022年第1期8卷 83-96页

作者： Taekyung Kim Sunmok Kwon Jeehyeon lee Joon Sang lee Shinill kang National Center for Optically-assisted high precision Mechanical Systems Yonsei UniversitySeoul 03722Korea School of Mechanical Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Korea

Metallic surface finishes have been used in the anti-biofouling,but it is very difficult to produce surfaces with hierarchically ordered *** the present study,anti-biofouling metallic surfaces with nanostructures superimposed on curved micro-riblets were produced via top-down *** to the attachment theory,these surfaces feature few attachment points for organisms,the nanostructures prevent the attachment of bacteria and algal zoospores,while the micro-riblets prohibit the settlement of *** oxidation was performed to induce *** forms a hydration layer on the surface,which physically blocks foulant adsorption along with the anti-biofouling *** characterized the surfaces via scanning electron and atomic force microscopy,contact-angle measurement,and wear-resistance *** contact angle of the hierarchical structures was less than 1°.Laboratory settlement assays verified that bacterial attachment was dramatically reduced by the nanostructures and/or the hydration layer,attributable to *** micro-riblets prohibited the settlement of *** 77 days of static immersion in the sea during summer,the metallic surface showed significantly less biofouling compared to a surface painted with an anticorrosive coating.

关键词： Anti-biofouling Superhydrophilic Hierarchical topography Metallic engineered surface Nanoimprinting,static immersion test,field trials

Measurement of biological age may help to assess the risk of colorectal adenoma in screening colonoscopy

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World Journal of Gastroenterology 2017年第37期23卷 6877-6883页

作者： Sang-Jung Kim Beom Jin Kim hyun kang Department of Internal Medicine Bundang Jesaeng Hospital Sungnam-si Department of Internal Medicine Chung-Ang University College of Medicine Department of Anesthesiology and Pain Medicine.Chung-Ang University College of Medicine

AIM To investigate the clinical utility of biological age(BA) measurement in screening colonoscopy for the detection of colorectal adenomas in the average-risk *** A consecutive series of asymptomatic subjects aged ≥ 30 years who underwent colonoscopy in routine check-ups were enrolled. Colorectal adenoma was classified according to size, number, and location. BAs were calculated using the MEDIAGETM Biological Age Measurement *** A total of 2696 subjects were investigated(1876 men and 820 women). The mean chronological age(CA) was 46.0 years and the mean BA was 44.7 years. Metabolic syndrome(MS) was diagnosed in 218 subjects(8.1%). The prevalence of overall colorectal adenoma was 23.1%(622/2,696). When the subjects were divided into four groups based on BA(≤ 39 years; 40-49 years; 50-59 years; ≥ 60 years), the prevalence of colorectal adenoma was increased as BA increased(P < 0.001). Colorectal adenoma located in the proximal colon was more prevalent in the BA-dominant group(BA-CA ≥ 5years) than the CA-dominant group(CA-BA ≥ 5 years)(P = 0.034). When the subjects were categorized into four groups according to MS and age gap between BA and CA, the incidence of colorectal adenoma increased with MS and BA-dominance(P < 0.05).CONCLUSION Measurement of BA may help to assess the risk of colorectal adenoma in screening colonoscopy.

关键词： Chronological age Biological age Colorectal adenoma Age gap

Spatial Ecology of Translocated and Resident Amur Ratsnakes(Elaphe schrenckii) in Two Mountain Valleys of South Korea

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Asian Herpetological Research 2011年第4期2卷 223-229页

作者： Jung-hyun lee Daesik PARK Department of Biology Kangwon National UniversityChuncheonKangwon 200-701South Korea Department of Environmental Resources Research National Institute of Environmental ResearchSeo-GuIncheon 404-708South Korea Division of Science Education Kangwon National UniversityChuncheonKangwon 200-701South Korea

The translocation of snakes has been viewed as a useful tool to augment declining populations and to mitigate human-wildlife conflicts, even though released snakes often exhibit relatively high mortality. We radio-tracked 13 Amur Ratsnakes （Elaphe schrenckii） in the Woraksan National Park in South Korea from July 2008 to May 2009. Two of these snakes were residents, and 11 had been illegally captured in areas remote from the study site and were donated by the park office. During the study period, six of the translocated snakes were lost： two were killed by predators, one died of unknown causes, and the radio signals of three of the snakes were lost. In the field, the ratsnakes laid eggs in early August, moved into hibemacula in late November, and moved away from the hibemacula in mid-April. Compared to the resident snakes, five of the translocated snakes traveled approximately 1.3 times farther per week, and the home ranges of the translocated snakes were three to six times larger than those of the resident snakes. In addition, the translocated snakes were found underground more frequently than the resident snakes. The management recommendations resulting from this study will guide biologists and land use managers in making appropriate decisions regarding release sites and the use of gravid females in the translocation of this endangered ratsnake.

关键词： Amur Ratsnake conservation Elaphe schrenckii radiotelemetry translocation

Depolarization mitigated in ferroelectric Hf_(0.5)Zr_(0.5)O_(2)ultrathin films(<5 nm)on Si substrate by interface engineering

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Journal of Advanced Ceramics 2024年第3期13卷 282-292页

作者： Se hyun Kim Younghwan lee Dong hyun lee Geun Hyeong Park hyun Woo Jeong Kun Yang Yong Hyeon Cho Young Yong Kim Min Hyuk Park Department of Materials Science and Engineering College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Research Institute of Advanced Materials College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Inter-university Semiconductor Research Center College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Pohang Accelerator Laboratory Pohang University of Science&TechnologyPohang 790784Republic of Korea

(Hf,Zr)O_(2)offers considerable potential for next-generation semiconductor devices owing to its nonvolatile spontaneous polarization at the ***,scaling this material to sub-5 nm thickness poses several challenges,including the formation of an interfacial layer and high trap *** particular,a low-k SiO_(2)interfacial layer is naturally formed when(Hf,Zr)O_(2)films are directly grown on a Si substrate,leading to high depolarization fields and rapid reduction of the remanent *** address these issues,we conducted a study to significantly improve ferroelectricity and switching endurance of(Hf,Zr)O_(2)films with sub-5 nm thicknesses by inserting a TiO_(2)interfacial *** deposition of a Ti film prior to Hf_(0.5)Zr_(0.5)O_(2)film deposition resulted in a high-k TiO_(2)interfacial layer and prevented the direct contact of Hf_(0.5)Zr_(0.5)O_(2)with *** findings show that the high-k TiO_(2)interfacial layer can reduce the SiO_(2)/Si interface trap density and the depolarization field,resulting in a switchable polarization of 60.2μC/cm^(2)for a 5 nm thick Hf_(0.5)Zr_(0.5)O_(2)***,we propose that inserting a high-k TiO_(2)interfacial layer between the Hf_(0.5)Zr_(0.5)O_(2)film and the Si substrate may offer a promising solution to enhancing the ferroelectricity and reliability of(Hf,Zr)O_(2)grown on the Si substrate and can pave the way for next-generation semiconductor devices with improved performance.

关键词： ferroelectric charge trapping hafnia depolarization

Smooth cutting pattern generation technique for membrane structures using geodesic line on subplane and spline interpolation

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Journal of Central South University 2013年第11期20卷 3131-3141页

作者： SHON Su-deok lee Seung-jae lee kang-guk School of Architectural Engineering Korea University of Technology and Education Research Center for Building safety Kyungpook National University

Practical techniques for smooth geodesic patterning of membrane structures were *** the geodesic search,adjustment of the subplane of the extracted elements series was proposed,and various spline approximation methods were used to flatten the strip for the generation of a smooth *** search approach is very simple,and the geodesic line could be easily attained by the proposed method without the need for a difficult computation *** cutting patterning can also be generated by spline approximation without the noise in discrete nodal ***,the geodesic cutting pattern saved about 21%of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.

关键词： membrane structures cutting pattern generation geodesic line spline interpolation triangular mesh sub-plane