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Enhanced four-wave mixing process near the excitonic resonances of bulk MoS_2

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Photonics Research 2019年第3期7卷 251-259页

作者： BRIAN A.KO ALEXEI V.SOKOLOV MARLAN O.SCULLY ZHENRONG ZHANG HO wai HOWARD lee Department of Physics Baylor University The Institute for Quantum Science and Engineering Texas A&M University College Station Princeton University Princeton

Two-dimensional materials are generating great interest due to their unique electrical and optical *** particular, transition metal dichalcogenides such as molybdenum disulfide(MoS_2) are attractive materials due to the existence of a direct band gap in the monolayer limit that can be used to enhance nonlinear optical phenomena, such as Raman spectroscopy. Here, we have investigated four-wave mixing processes in bulk MoS_2 using a multiplex coherent anti-Stokes Raman spectroscopy setup. The observed four-wave mixing signal has a resonance at approximately 680 nm, corresponding to the energy of the A excitonic transition of MoS_2. This resonance can be attributed to the increased third-order nonlinear susceptibility at wavelengths near the excitonic transition. This phenomenon could open the path to using MoS_2 as a substrate for enhancing four-wave mixing processes such as coherent anti-Stokes Raman spectroscopy.

关键词： Two-dimensional materials excitonic resonances MoS2

A Review on Soft Ionic Touch Point Sensors

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Energy & Environmental Materials 2024年第6期7卷 193-208页

作者： Gibeom lee Donghyun lee Gwang-Bum Im Younghoon lee Department of Mechanical Engineering Gachon University1342 SeongnamdaeroSujeong-guSeongnam 13120South Korea Department of Surgery Harvard Medical SchoolBostonMassachusetts 02115USA

A touch sensor is an essential component in meeting the growing demand for human-machine *** sensors have been developed in wearable,attachable,and even implantable forms to acquire a wide range of information from *** be applied to the human body,sensors are required to be biocompatible and not restrict the natural movement of the *** materials are a promising candidate for soft touch sensors due to their outstanding properties,which include high stretchability,transparency,ionic conductivity,and ***,this review discusses the unique features of soft ionic touch point sensors,focusing on the ionic material and its key role in the *** touch sensing mechanisms include piezocapacitive,piezoresistive,surface capacitive,piezoelectric,and triboelectric and triboresistive *** review analyzes the implementation hurdles and future research directions of the soft ionic touch sensors for their transformative potential.

关键词： iontronics ionic materials soft materials touch sensors

TAKOTSUBO SYNDROME WITH TRANSIENT COMPLETE ATRIOVENTRICULAR BLOCK

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Chinese Medical Journal 2006年第1期119卷 73-76页

作者： lee wai Luen Stephen MIAO Li-fu CHAN Hon Wah Ryamond CHEN Ming-zhe Division of Cardiology Department of Medicine Queen Mary Hospital Hong Kong China Center of Cardiology First Hospital of Tsinghua University Beijing 100016 China

Takotsubo syndrome （transient left ventricular apical ballooning syndrome） is a novel cardiac syndrome of left ventricular apical ballooning involving reversible left ventricular apical ballooning （during systole） of acute onset with chest pain, electrocardiographic changes, and minimal elevation of cardiac enzymes resembling acute myocardial infarction, but without evidence of myocardial ischemia or injury.

关键词： Takotsubo syndrome transient left ventricular apical ballooning syndrome

Explainable Artificial Intelligence-Based Model Drift Detection Applicable to Unsupervised Environments

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Computers, Materials & Continua 2023年第8期76卷 1701-1719页

作者： Yongsoo lee Yeeun lee Eungyu lee Taejin lee Department of Information Security Hoseo UniversityAsan31499Korea

Cybersecurity increasingly relies on machine learning(ML)models to respond to and detect ***,the rapidly changing data environment makes model life-cycle management after deployment ***-time detection of drift signals from various threats is fundamental for effectively managing deployed ***,detecting drift in unsupervised environments can be *** study introduces a novel approach leveraging Shapley additive explanations(SHAP),a widely recognized explainability technique in ML,to address drift detection in unsupervised *** proposed method incorporates a range of plots and statistical techniques to enhance drift detection reliability and introduces a drift suspicion metric that considers the explanatory aspects absent in the current *** validate the effectiveness of the proposed approach in a real-world scenario,we applied it to an environment designed to detect domain generation algorithms(DGAs).The dataset was obtained from various types of DGAs provided by *** on this dataset composition,we sought to validate the proposed SHAP-based approach through drift scenarios that occur when a previously deployed model detects new data types in an environment that detects real-world *** results revealed that more than 90%of the drift data exceeded the threshold,demonstrating the high reliability of the approach to detect drift in an unsupervised *** proposed method distinguishes itself fromexisting approaches by employing explainable artificial intelligence(XAI)-based detection,which is not limited by model or system environment *** conclusion,this paper proposes a novel approach to detect drift in unsupervised ML settings for *** proposed method employs SHAP-based XAI and a drift suspicion metric to improve drift detection *** is versatile and suitable for various realtime data analysis contexts beyond DGA detection *** study significan

关键词： Cybersecurity machine learning(ML) model life-cycle management drift detection unsupervised environments shapley additive explanations(SHAP) explainability

Development of a Hand Exoskeleton System for Quantitative Analysis of Hand Functions

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Journal of Bionic Engineering 2018年第5期15卷 783-794页

作者： Jeongsoo lee Minhyuk lee Joonbum Bae Bio-Robotics and Control (BiRC) Laboratory Department of Mechanical Engineering UNIST Ulsan Republic of Korea

This paper proposes a hand exoskeleton system for evaluating hand functions. To evaluate hand functions, the hand exoskeleton system must be able to pull each finger joint, measure the finger joint angle and exerted force on the finger simultaneously. The proposed device uses serially connected 4-bar linkage structures, which have two embedded actuators with encoders and two loadcells per finger, to move each phalanx independently and measure the finger joint angles. A modular design was used for the exoskeleton, to facilitate the removal of unnecessary modules in different experiments and improve convenience. Silicon was used on the surface of the worn part to reduce the skin irritation that results from prolonged usage. This part was also designed to be compatible with various finger thicknesses. Using the proposed hand exoskeleton system, finger independence, multi-finger synergy, and finger joint stiffness were determined in five healthy subjects. The finger movement and force data collected in the experiments were used for analyzing three hand functions based on the physical and physiological phenomena.

关键词： evaluation of hand function hand rehabilitation wearable system exoskeleton

ZnO-Embedded Expanded Graphite Composite Anodes with Controlled Charge Storage Mechanism Enabling Operation of Lithium-Ion Batteries at Ultra-Low Temperatures

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Energy & Environmental Materials 2023年第4期6卷 31-39页

作者： Kun Ryu Michael J.lee Kyungbin lee Seung Woo lee George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly ***,the lowtemperature performance of conventional graphite anodes is severely hampered by the poor diffusion kinetics of Li ions(Li^(+)).Here,zinc oxide(ZnO) nanoparticles are incorporated into the expanded graphite to improve Li^(+)diffusion kinetics,resulting in a significant improvement in lowtemperature *** ZnO-embedded expanded graphite anodes are investigated with different amounts of ZnO to establish the structurecharge storage mechanism-performance relationship with a focus on lowtemperature *** analysis reveals that the ZnOembedded expanded graphite anode with nano-sized ZnO maintains a large portion of the diffusion-controlled charge storage mechanism at an ultra-low temperature of-50℃ Due to this significantly enhanced Li^(+)diffusion rate,a full cell with the ZnO-embedded expanded graphite anode and a LiNi_(0.88)Co_(0.09)Al_(0.03)O_(2)cathode delivers high capacities of 176 mAh g^(-1)at20℃ and 86 mAh g^(-1)at-50℃ at a high rate of 1 *** outstanding low-temperature performance of the composite anode by improving the Li^(+)diffusion kinetics provides important scientific insights into the fundamental design principles of anodes for low-temperature Li-ion battery operation.

关键词： diffusive and capacitive charge storages expanded graphite composites anode lithium-ion battery low-temperature operation transition metal oxide

Mining Semantic Trajectory Patterns from Geo-Tagged Data

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Journal of Computer Science & Technology 2018年第4期33卷 849-862页

作者： Guochen Cai Kyungmi lee Ickjai lee Information Technology Academy College of Business Law and Governance James Cook University Queensland QLD 4870 Australia

User-generated social media data tagged with geographic information present messages of dynamic spatiotemporal trajectories. These increasing mobility data provide potential opportunities to enhance the understanding of human mobility behaviors. Several trajectory data mining approaches have been proposed to benefit from these rich datasets, but fail to incorporate aspatial semantics in mining. This study investigates mining frequent moving sequences of geographic entities with transit time from geo-tagged data. Different from previous analysis of geographic feature only trajectories, this work focuses on extracting patterns with rich context semantics. We extend raw geographic trajectories generated from geo-tagged data with rich context semantic annotations, use regions-of-interest as stops to represent interesting places, enrich them with multiple aspatial semantic annotations, and propose a semantic trajectory pattern mining algorithm that returns basic and multidimensional semantic trajectory patterns. Experimental results demonstrate that semantic trajectory patterns from our method present semantically meaningful patterns and display richer semantic knowledge.

关键词： semantic trajectory spatio-temporal geo-tagged data trajectory pattern mining

Topic Modeling Based Warning Prioritization from Change Sets of Software Repository

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Journal of Computer Science & Technology 2020年第6期35卷 1461-1479页

作者： Jung-Been lee Taek lee Hoh Peter In College of Informatics Korea UniversitySeoul 02841Korea College of Knowledge-Based Services Engineering Sungshin UniversitySeoul 02844Korea

Many existing warning prioritization techniques seek to reorder the static analysis warnings such that true positives are provided first. However, excessive amount of time is required therein to investigate and fix prioritized warnings because some are not actually true positives or are irrelevant to the code context and topic. In this paper, we propose a warning prioritization technique that reflects various latent topics from bug-related code blocks. Our main aim is to build a prioritization model that comprises separate warning priorities depending on the topic of the change sets to identify the number of true positive warnings. For the performance evaluation of the proposed model, we employ a performance metric called warning detection rate, widely used in many warning prioritization studies, and compare the proposed model with other competitive techniques. Additionally, the effectiveness of our model is verified via the application of our technique to eight industrial projects of a real global company.

关键词： automated static analysis topic modeling warning prioritization

Guiding Attention by Cooperative Cues

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Journal of Computer Science & Technology 2008年第5期23卷 874-884页

作者： KangWoo lee School of Media Soongsil University 1-1 Sangdo-5 Dong Dong-Jak Ku Seoul 156-743 Korea

A common assumption in visual attention is based on the rationale of ＂limited capacity of information processing＂. From this view point there is little consideration of how different information channels or modules are cooperating because cells in processing stages are forced to compete for the limited resource. To examine the mechanism behind the cooperative behavior of information channels, a computational model of selective attention is implemented based on two hypotheses. Unlike the traditional view of visual attention, the cooperative behavior is assumed to be a dynamic integration process between the bottom-up and top-down information. Furthermore, top-down information is assumed to provide a contextual cue during selection process and to guide the attentional allocation among many bottom-up candidates. The result from a series of simulation with still and video images showed some interesting properties that could not be explained by the competitive aspect of selective attention alone.

关键词： selective attention cooperation competition cooperative cues guidance