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A Rapid Adaptation Approach for Dynamic Air‑Writing Recognition Using Wearable Wristbands with Self‑Supervised Contrastive Learning

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Nano-Micro Letters 2025年第2期17卷 417-431页

作者： Yunjian Guo Kunpeng Li Wei Yue Nam‑Young Kim Yang Li Guozhen Shen Jong‑Chul Lee Department of Electronic Convergence Engineering Kwangwoon UniversitySeoul 01897South Korea Radio Frequency Integrated Circuit(RFIC)Bio Centre Kwangwoon UniversitySeoul 01897South Korea Department of Electronic Engineering Kwangwoon UniversitySeoul 01897South Korea school of Microelectronics Shandong UniversityJinan 250101People’s Republic of China State Key Laboratory of Integrated Chips and Systems Fudan UniversityShanghai 200433People’s Republic of China school of Integrated Circuits and Electronics Beijing Institute of TechnologyBeijing 100081People’s Republic of China

Wearable wristband systems leverage deep learning to revolutionize hand gesture recognition in daily *** existing approaches that often focus on static gestures and require extensive labeled data,the proposed wearable wristband with selfsupervised contrastive learning excels at dynamic motion tracking and adapts rapidly across multiple *** features a four-channel sensing array composed of an ionic hydrogel with hierarchical microcone structures and ultrathin flexible electrodes,resulting in high-sensitivity capacitance *** wireless transmission from a Wi-Fi module,the proposed algorithm learns latent features from the unlabeled signals of random wrist ***,only few-shot labeled data are sufficient for fine-tuning the model,enabling rapid adaptation to various *** system achieves a high accuracy of 94.9%in different scenarios,including the prediction of eight-direction commands,and air-writing of all numbers and *** proposed method facilitates smooth transitions between multiple tasks without the need for modifying the structure or undergoing extensive task-specific *** utility has been further extended to enhance human–machine interaction over digital platforms,such as game controls,calculators,and three-language login systems,offering users a natural and intuitive way of communication.

关键词： Wearable wristband Self-supervised contrastive learning Dynamic gesture Air-writing Human-machine interaction

Aligned Ion Conduction Pathway of Polyrotaxane‑Based Electrolyte with Dispersed Hydrophobic Chains for Solid‑State Lithium–Oxygen Batteries

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Nano-Micro Letters 2025年第2期17卷 169-186页

作者： Bitgaram Kim Myeong‑Chang Sung Gwang‑Hee Lee Byoungjoon Hwang Sojung Seo Ji‑Hun Seo Dong‑Wan Kim Department of Materials Science and Engineering Korea University145 Anam‑RoSeongbuk‑GuSeoul 02841Republic of Korea school of Civil Environmental and Architectural EngineeringKorea University145 Anam‑RoSeongbuk‑GuSeoul 02841Republic of Korea Materials Science and Chemical Engineering Center Institute for Advanced Engineering(IAE)Yongin 17180Republic of Korea

A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety *** study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves ***-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain *** this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 *** situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen *** situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability *** present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.

关键词： Solid polymer electrolyte Lithium-oxygen batteries Polyrotaxane ion conductivity Hydrophobic chain

Factors associated with significant liver fibrosis assessed using transient elastography in general population

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World Journal of Gastroenterology 2015年第4期21卷 1158-1166页

作者： Seng Chan You Kwang Joon Kim Seung Up Kim Beom Kyung Kim Jun Yong Park Do Young Kim Sang Hoon Ahn Won Jae Lee Kwang-Hyub Han Department of Internal Medicine Yonsei University College of MedicineSeoul 120-752South Korea Division of Endocrinology and Metabolism Yonsei University College of MedicineSeoul 120-752South Korea Institute of Gastroenterology Yonsei University College of MedicineSeoul 120-752South Korea Liver Cirrhosis Clinical Research Center Seoul 120-752South Korea seoul gookgwain school Seoul 110-521South Korea

AIM: To investigate the prevalence of significant liver fibrosis assessed using transient elastography(TE) and its predictors in asymptomatic general ***: A total of 159 subjects without chronic viral hepatitis who underwent comprehensive medical health check-up between January 2012 and July 2012 were prospectively recruited. Significant liver fibrosis was defined as liver stiffness value > 7.0 k ***: The mean age and body mass index(BMI) of the study population(men 54.7%) was 56.0 years and 24.3 kg/m2. Among the study subjects, 11(6.9%) showed significant liver fibrosis. On univariate analysis, BMI, alanine aminotransferase(ALT), homeostasis model assessment of insulin resistance, carotid intimal media thickness(IMT), number of calcified plaques on carotid ultrasound, and visceral fat area on computed tomography were significantly higher in subjects with significant liver fibrosis than in those without(all P < 0.05). However, on multivariate analysis, BMI [odds ratio(OR) =1.487; P = 0.045], ALT(OR = 1.078; P = 0.014), carotid IMT(OR = 3.244; P = 0.027), and the number of calcified carotid plaques(OR = 1.787; P = 0.031) were independent predictors of significant liver fibrosis. CONCLUSION: The prevalence of significant liver fibrosis assessed using TE was 6.9% in apparently healthy subjects. High BMI, high ALT, thicker carotid IMT, and higher numbers of calcified carotid plaqueswere independently associated with the presence of significant liver fibrosis.

关键词： Transient elastography Healthy subjects Fibroscan

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

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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

Femtosecond Tm-Ho co-doped fiber laser using a bulk-structured Bi2Se3 topological insulator

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Chinese Physics B 2018年第9期27卷 137-143页

作者： Jinho Lee Ju Han Lee school of Electrical and Computer Engineering University of SeoulSeoul 02504Republic of Kore

We experimentally demonstrate a femtosecond mode-locked thulium-holmium（Tm-Ho） co-doped fiber laser incorporating a saturable absorber（SA） based on a bulk-structured bismuth selenide（Bi2Se3） topological insulator（TI）. The SA was prepared by depositing a mechanically exfoliated Bi2Se3 TI layer onto a side-polished optical fiber platform. Unlike high-quality nano-structured Bi2Se3 TI-based SA, bulk-structured Bi2Se3 with non-negligible oxidation was used as a saturable absorption material for this experimental demonstration due to its easy fabrication process. The saturation power and modulation depth of the prepared SA were measured to be -28.6 W and -13.4%, respectively. By incorporating the prepared SA into a Tm-Ho co-doped fiber ring cavity, stable soliton pulses with a temporal width of - 853 fs could be generated at 1912.12 nm. The 3-dB bandwidth of the mode-locked pulse was measured to be -4.87 nm. This experimental demonstration reaffirms that Bi2Se3 is a superb base material for mid-infrared passive mode-locking even under oxidation.

关键词： topological insulator mode-locked lasers femtosecond pulse fiber lasers

ANISOTROPIC POLARIZATION TENSORS FOR ELLIPSES AND ELLIPSOIDS

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Journal of Computational Mathematics 2007年第2期25卷 157-168页

作者： Hyeonbae Kang Kyoungsun Kim school of Mathematical Sciences Seoul National University Seoul 151-737 Korea

In this paper we present a systematic way of computing the polarization tensors, anisotropic as well as isotropic, based on the boundary integral method. We then use this method to compute the anisotropic polarization tensor for ellipses and ellipsoids. The computation reveals the pair of anisotropy and ellipses which produce the same polarization tensors.

关键词： Anisotropic polarization tensor Integral equation Ellipsoid

Successful hemostasis of intractable rectal variceal bleeding using variceal embolization

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World Journal of Gastroenterology 2015年第8期21卷 2558-2562页

作者： Sung Soo Ahn Eun Hye Kim Man Deuk Kim Won Jae Lee Seung Up Kim Department of Internal Medicine Yonsei University College of Medicine Department of Radiology Research Institute of Radiological Science Yonsei University College of Medicine seoul gookgwain school Institute of Gastroenterology Yonsei University College of Medicine Liver Cirrhosis Clinical Research Center

Portal hypertension causes portosystemic shunting along the gastrointestinal tract,resulting in *** varices and their bleeding is a rare complication,but it can be fatal without appropriate ***,because of its rarity,no established treatment strategy is yet *** the setting of intractable rectal variceal bleeding,a transjugular intravenous portosystemic shunt can be a treatment of choice to enable portal decompression and thus achieve ***,in the case of recurrent rectal variceal bleeding despite successful transjugular intravenous portosystemic shunt,alternative measures to control bleeding are ***,we report on a patient with liver cirrhosis who experienced recurrent rectal variceal bleeding even after successful transjugular intravenous portosystemic shunt and was successfully treated with variceal embolization.

关键词： Ectopic varices Rectal varices Transjugular intrav

Diurnal Variation of Tropical Convection during TOGA COARE IOP

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Advances in Atmospheric Sciences 2005年第5期22卷 685-702页

作者： Jae-Young BYON Gyu-Ho LIM school of Earth and Environmental Sciences Seoul National University Seoul South KoreaSchool of Earth and Environmental Sciences Seoul National University Seoul South Korea

Diurnal variation of tropical convection and kinematic and thermodynamic conditions was investigated for different large-scale environments of the convectively active and inactive periods by using satellite observations and surface measurements during the Intensive Observation Period （IOP） of the Tropical Ocean Global Atmosphere/Coupled Ocean-Atmosphere Response Experiment （TOGA/COARE）. During the convectively active period, the features of nocturnal convection appear in vertical profiles of convergence, vertical velocity, heat source, and moisture sink. The specific humidity increases remarkably in the middle troposphere at dawn. On the other hand, the altitude of maximum convergence and that of the upward motion is lower during the convectively inactive period. The specific humidity peaks in the lower troposphere in the daytime and decreases in the middle troposphere. Spectral analyses of the time series of the infrared （IR） brightness temperature （TBB） and amounts of rainfall suggest multiscale temporal variation with a prominent diurnal cycle over land and oceanic regions such as the Intensive Flux Array （IFA） and the South Pacific Convergence Zone （SPCZ）. Over land, the daily maximum of deep convection associated with cloud top temperature less than 208 K appears at midnight due to the daytime radiative heating and the sea-land breeze. Over the ocean, convection usually tends to occur at dawn for the convectively active period while in the afternoon during the inactive period. Comparing the diurnal variation of convection with large-scale variables, the authors inferred that moisture in the middle troposphere contributes mostly to the development of nocturnal convection over the ocean during the convectively active period.

关键词： diurnal variation tropical convection rainfall large-scale environment

Passively Q-switched ytterbium-doped fiber laser using the evanescent field interaction with bulk-like WTe_2 particles

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Chinese Optics Letters 2018年第2期16卷 108-112页

作者： Seunghwan Ko Jinho Lee Ju Han Lee school of Electrical and Computer Engineering University of Seoul Seoul 02504 Republic of Kore

The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.

关键词： length Passively Q-switched ytterbium-doped fiber laser using the evanescent field interaction with bulk-like WTe2 particles SA