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Histogram equalization using a reduced feature set of background speakers' utterances for speaker recognition

Frontiers of Information Technology & Electronic Engineering 2017年第5期18卷 738-750页

作者： myung-jae kim Il-ho YANG Min-seok kim Ha-jin YU School of Computer Science University of Seoul

We propose a method for histogram equalization using supplement sets to improve the performance of speaker recognition when the training and test utterances are very short. The supplement sets are derived using outputs of selection or clustering algorithms from the background speakers' utterances. The proposed approach is used as a feature normalization method for building histograms when there are insufficient input utterance *** addition, the proposed method is used as an i-vector normalization method in an i-vector-based probabilistic linear discriminant analysis(PLDA) system, which is the current state-of-the-art for speaker verification. The ranks of sample values for histogram equalization are estimated in ascending order from both the input utterances and the supplement set. New ranks are obtained by computing the sum of different kinds of ranks. Subsequently, the proposed method determines the cumulative distribution function of the test utterance using the newly defined ranks. The proposed method is compared with conventional feature normalization methods, such as cepstral mean normalization(CMN), cepstral mean and variance normalization(MVN), histogram equalization(HEQ), and the European Telecommunications Standards Institute(ETSI) advanced front-end methods. In addition, performance is compared for a case in which the greedy selection algorithm is used with fuzzy C-means and K-means *** YOHO and Electronics and Telecommunications Research Institute(ETRI) databases are used in an evaluation in the feature space. The test sets are simulated by the Opus Vo IP codec. We also use the 2008 National Institute of Standards and Technology(NIST) speaker recognition evaluation(SRE) corpus for the i-vector system. The results of the experimental evaluation demonstrate that the average system performance is improved when the proposed method is used, compared to the conventional feature normalization methods.

关键词： Speaker recognition Histogram equalization i-vector

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Multi-Stream CNN-Based Personal Recognition Method Using Surface Electromyogram for 5G Security

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Computers, Materials & Continua 2022年第8期72卷 2997-3007页

作者： Jin Su kim Min-Gu kim jae myung kim Sung Bum Pan IT Research Institute Chosun UniversityGwangju61452Korea Interdisciplinary Program in IT-Bio Convergence System Chosun UniversityGwangju61452Korea

As fifth generation technology standard(5G)technology develops,the possibility of being exposed to the risk of cyber-attacks that exploits vulnerabilities in the 5G environment is *** existing personal recognitionmethod used for granting permission is a password-basedmethod,which causes security ***,personal recognition studies using bio-signals are being conducted as a method to access control to *** bio-signal,surface electromyogram(sEMG)can solve the existing personal recognition problem that was unable to the modification of registered information owing to the characteristic changes in its signal according to the performed ***,as an advantage,sEMG can be conveniently measured from arms and *** paper proposes a personal recognition method using sEMG,based on a multi-stream convolutional neural network(CNN).The proposed method decomposes sEMG signals into intrinsic mode functions(IMF)using empirical mode decomposition(EMD)and transforms each IMF into a *** recognition is performed by analyzing time–frequency features from the spectrogram transformed *** database(DB)adopted in this paper is the Ninapro DB,which is a benchmark EMG *** experimental results indicate that the personal recognition performance of the multi-stream CNN using the IMF spectrogram improved by 1.91%,compared with the singlestream CNN using the spectrogram of raw sEMG.

关键词： Personal recognition electromyogram signal multi-stream network empirical mode decomposition

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User Recognition System Based on Spectrogram Image Conversion Using EMG Signals

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Computers, Materials & Continua 2022年第7期72卷 1213-1227页

作者： jae myung kim Gyu Ho Choi Min-Gu kim Sung Bum Pan Interdisciplinary Program in IT-Bio Convergence System Chosun UniversityGwangju61452Korea IT Research Institute Chosun UniversityGwangju61452Korea

Recently,user recognitionmethods to authenticate personal identity has attracted significant attention especially with increased availability of various internet of things(IoT)services through fifth-generation technology(5G)based mobile *** EMG signals generated inside the body with unique individual characteristics are being studied as a part of nextgeneration user recognition ***,there is a limitation when applying EMG signals to user recognition systems as the same operation needs to be repeated while maintaining a constant strength of muscle over ***,it is necessary to conduct research on multidimensional feature transformation that includes changes in frequency features over *** this paper,we propose a user recognition system that applies EMG signals to the short-time fourier transform(STFT),and converts the signals into EMG spectrogram images while adjusting the time-frequency resolution to extract multidimensional *** proposed system is composed of a data pre-processing and normalization process,spectrogram image conversion process,and final classification *** experimental results revealed that the proposed EMG spectrogram image-based user recognition system has a 95.4%accuracy performance,which is 13%higher than the EMGsignal-based *** a user recognition accuracy improvement was achieved by using multidimensional features,in the time-frequency domain.

关键词： EMG user recognition spectrogram CNN

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Nanoparticle Exsolution on Perovskite Oxides:Insights into Mechanism,Characteristics and Novel Strategies

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Nano-Micro Letters 2024年第2期16卷 312-346页

作者： Yo Han kim Hyeongwon Jeong Bo‑Ram Won Hyejin Jeon Chan‑ho Park Dayoung Park Yeeun kim Somi Lee jae‑ha myung Department of Materials Science and Engineering Incheon National UniversityIncheon 22012Republic of Korea

Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications,including fuel cells,chemical conversion,and *** demonstrate high activity by expanding the number of active sites,but they also intensify deactivation issues,such as agglomeration and poisoning,*** for bottomup synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional *** are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction *** uniformity and stability,resulting from the socketed structure,play a crucial role in the development of novel ***,tremendous research efforts have been dedicated to further controlling exsolution *** effectively address exsolution at a more precise level,understanding the underlying mechanism is *** review presents a comprehensive overview of the exsolution mechanism,with a focus on its driving force,processes,properties,and synergetic strategies,as well as new pathways for optimizing nanocatalysts in diverse applications.

关键词： Supported nanoparticle Exsolution In situ growth Mechanism Perovskite oxide Catalyst

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Driving inward growth of lithium metal in hollow microcapsule hosts by heteroatom‐controlled nucleation

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Carbon Energy 2024年第8期6卷 262-272页

作者： Siwon kim Hong Rim Shin Ki jae kim Min‐Sik Park Jong‐Won Lee Division of Materials Science and Engineering Hanyang UniversitySeoulRepublic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)DaeguRepublic of Korea Department of Energy Science Sungkyunkwan UniversitySuwonRepublic of Korea Department of Advanced Materials Engineering for Information and Electronics Integrated Education for Frontier Science and Technology(BK21 Four)Kyung Hee UniversityYonginRepublic of Korea

The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li ***‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity;however,uncontrollable and nonuniform deposition of Li remains a *** this study,we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters(Zn and Ag)on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule ***‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag^(+)and metallic *** introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li *** combined electrochemical,microstructural,and computational studies,we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and,in turn,enhancing electrochemical *** study provides new insights into the design of reversible host materials for practical Li metal batteries.

关键词： hollow carbon hosts lithium metal batteries lithium plating metal-organic frameworks nucleation

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Modification strategies improving the electrochemical and structural stability of high-Ni cathode materials

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Journal of Energy Chemistry 2024年第9期96卷 185-205页

作者： Yoon Bo Sim Hami Lee Junyoung Mun Ki jae kim Department of Energy Science Sungkyunkwan UniversitySuwon 16419Republic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwon 16419Republic of Korea

With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving ***,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)***,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization *** direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode ***,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk *** this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode *** also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.

关键词： High energy density High-Ni cathode materials Degradation Structural stability Lithium-ion battery

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Opportunities and challenges in cathode development for non-lithium-ion batteries

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eScience 2024年第4期4卷 1-6页

作者： Haegyeom kim jae Chul kim Materials Sciences Division Lawrence Berkeley National Laboratory94720CAUSA Department of Chemical Engineering and Materials Science Stevens Institute of Technology07030NJUSA

Lithium(Li)-ion batteries have stimulated the societal transformation to clean energy *** carry-on electricity is revolutionizing how society communicates,functions,and evolves efficiently by enabling mobile electronics,zero-emission electric vehicles,and stationary energy *** preparation for the sustainable energy future,however,there are growing concerns about depleting critical elements used in the Li technology(e.g.,lithium,cobalt,and nickel),especially for large-scale applications that will accelerate the rate of elemental *** non-Li-based rechargeable batteries composed of earth-abundant elements,such as sodium,potassium,magnesium,and calcium,have been proposed and explored as alternative systems to promote sustainable development of energy *** this perspective,we discuss challenges in Li-ion batteries in the sustainability aspect and provide our opinions on the potential applications of non-Li-based *** also highlight the current status,important progress,and remaining challenges of the Li-alternative technologies.

关键词： Batteries Sodium Potassium Lithium Multi-valent Energy storage

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Comparative efficacy and optimal duration of first-line antibiotic regimens for acute otitis media in children and adolescents:a systematic review and network meta-analysis of 89 randomized clinicaltrials

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World Journal of Pediatrics 2024年第3期20卷 219-229页

作者： Min Seo kim jae Han kim Seohyun Ryu Seung Won Lee Dong Keon Yon Eunyoung kim Ai Koyanagi Elena Dragioti jae Il Shin Lee Smith Samsung Advanced Institute forHealth Sciences&Technology(SAIHST) Samsung Medical CenterSungkyunkwan UniversitySeoulRepublic of Korea Yonsei University Collegeof Medicine SeoulRepublicof Korea Department of Precision Medicine Sungkyunkwan University School of MedicineSuwonRepublic of Korea Center for Digital Health Medical Science Research InstituteKyung Hee University College of MedicineSeoulRepublic of Korea Evidence-Based Research Laboratory Department of Clinical Pharmacy and Pharmaceutical CareCollege of PharmacyChung-Ang UniversitySeoulRepublic of Korea Parc Sanitari Sant Joan de Deu/CIBERSAM/ISCIII Universitat de BarcelonaFundacio Sant Joan de Déu.Sant Boi de LlobregatBarcelonaSpain ICREA Pg.Lluis Companys 23BarcelonaSpain Pain and Rehabilitation Centre and Department of Medical and Health SciencesLinkoping University58185 LinkopingSweden Department of Pediatrics Yonsei University College of MedicineYonsei-ro 50Seodaemun-gu8044Seoul 03722Republic of Korea Centre for Health Performanceand WellbeingAnglia Ruskin UniversityCambridge CB11PTUK Research Laboratory Psychology of Patients Families&Health ProfessionalsDepartment of NursingSchool of Health SciencesUniversity of IoanninaIoannina 45500Greece

Introduction Antibiotic use for acute otitis media(AOM)is one of the major sources of antimicrobial ***,the effective minimal antibiotic duration for AOM remains ***,guidelines often recommend broad ranges(5-10 days)of antibiotic use,yet the clinical impact of such a wide window has not been *** We systematically searched PubMed/MEDLINE,Embase,Scopus,Web of Science,and Cochrane Library from database inception to 6 October *** meta-analysis was conducted on randomized controlled trials that assessed antibiotic treatment for AOM in children(PROSPERO CRD42020196107).Results For amoxicillin and amoxicillin-clavulanate,7-day regimens were noninferior to 10-day regimens in clinical responses[amoxicillin:risk ratio(RR)0.919(95%CI 0.820-1.031),amoxicillin-clavulanate:RR 1.108(0.957-1.282)],except for≤2 *** the third-generation cephalosporins,7-day and 10-day regimens had similar clinical responses compared to placebo[7-day:RR 1.420(1.190-1.694),10-day:RR 1.238(1.125-1.362)compared to placebo].However,5-day regimens of amoxicillin-clavulanate and third-generation cephalosporins were inferior to 10-day *** to amoxicillin,a shorter treatment duration was tolerable with *** Our findings indicated that 1O days of antibiotic use may be unnecessarily long,while the treatment duration should be longer than 5 ***,5-day regimens would be sufficient for a modest treatment *** findings revealed that the current wide range of recommended antibiotic durations may have influenced the clinical outcome of AOM,and a narrower antibiotic duration window should be re-established.

关键词： Amoxicillin-potassium Amoxicillin Antibacterial agents Cephalosporins Duration of therapy

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SOME LIOUVILLE-TYPE THEOREMS FOR THE STATIONARY 3D MAGNETO-MICROPOLAR FLUIDS

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Acta Mathematica Scientia 2024年第6期44卷 2296-2306页

作者： jae-Myoung kim Seungchan KO Department of Mathematics Education Andong National University Department of Mathematics Inha University

In this paper,we prove some Liouville-type theorems for the stationary magnetomicropolar fluids under suitable conditions in three space *** first prove that the solutions are trivial under the assumption of certain growth conditions for the mean oscillations of the *** then we show similar results assuming that the solutions are contained in Lp（R3） with p ∈ [2,9/2).Finally,we show the same result for lower values of p ∈ [1,9/4) with the further assumption that the solutions vanish at infinity.

关键词： Liouville-type theorem stationary magneto-micropolar equations

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Electrochemically Deposited CZTSSe Thin Films for Monolithic Perovskite Tandem Solar Cells with Efficiencies Over 17%

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Energy & Environmental Materials 2024年第1期7卷 147-152页

作者： Sun Kyung Hwang Ik jae Park Se Won Seo jae Hyun Park So Jeong Park Jin Young kim Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Korea Department of Applied Physics Sookmyung Women's UniversitySeoul 04310Korea Research Institute of Advanced Materials and Systems Sookmyung Women's UniversitySeoul 04310Korea Research Institute of Advanced Materials(RIAM) Seoul National UniversitySeoul 08826Korea

In spite of the high potential economic feasibility of the tandem solar cells consisting of the halide perovskite and the kesterite Cu2ZnSn(S,Se)4(CZTSSe),they have rarely been demonstrated due to the difficulty in implementing solution-processed perovskite top cell on the rough surface of the bottom ***,we firstly demonstrate an efficient monolithic two-terminal perovskite/CZTSSe tandem solar cell by significantly reducing the surface roughness of the electrochemically deposited CZTSSe bottom *** surface roughness(R_(rms))of the CZTSSe thin film could be reduced from 424 to 86 nm by using the potentiostatic mode rather than using the conventional galvanostatic mode,which can be further reduced to 22 nm after the subsequent ion-milling *** perovskite top cell with a bandgap of 1.65 eV could be prepared using a solution process on the flattened CZTSSe bottom cell,resulting in the efficient perovskite/CZTSSe tandem solar *** the current matching between two subcells involving the thickness control of the perovskite layer,the best performing tandem device exhibited a high conversion efficiency of 17.5%without the hysteresis effect.

关键词： CZTSSe monolithic tandem solar cells perovskite solution process surface roughness control

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