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Thresholdless coherence in a superradiant laser

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Light(Science & Applications) 2024年第11期13卷 2549-2555页

作者： seung-Hoon Oh Jinuk kim Junseo Ha Gibeom Son Kyungwon An Department of Physics and Astronomy&Institute of Applied Physics Seoul National UniversitySeoulKorea Korea Research Institute of Standards and Science DaejeonKorea

Lasing threshold in the conventional lasers is the minimum input power required to initiate laser *** has been widely accepted that the conventional laser threshold occurring around a unity intracavity photon number can be eliminated in the input-output curve by making the so-calledβparameter approach *** recent experiments,however,have revealed that even in this case the photon statistics still undergo a transition from coherent to thermal statistics when the intracavity mean photon number is decreased below *** the coherent output is only available above the diminished threshold,the long-sought promise of thresholdless lasers to produce always coherent light has become ***,we present an always-coherent thresholdless laser based on superradiance by two-level atoms in a quantum superposition state with the same phase traversing a high-Q *** lasing was observed without the conventional lasing threshold around the unity photon number and the photon statistics remained near coherent even below *** coherence was improved by reducing the coupling constant as well as the excited-state amplitude in the superposition *** results pave a way toward always-coherent thresholdless lasers with more practical media such as quantum dots,nitrogen-vacancy centers and doped ions in crystals.

关键词： laser coherent lasing

Fabrication of heteroatom-doped cobalt oxide yolk-shell microsphere using recycled solution from waste materials and their excellent electrochemical properties as an anode material for lithium-ion batteries

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Rare Metals 2024年第10期43卷 4934-4947页

作者： Yeong Beom kim Chanho kim seung-Hyun kim Yun Chan Kang Dongju Lee Gi Dae Park Department of Advanced Materials Engineering Chungbuk National UniversityChungbuk 28644Korea Department of Materials Science and Engineering Korea UniversitySeoul 136-713Korea Research Institute YKSintering Co.Ltd.Chungbuk 28581Korea

Heteroatom-doped transition metal oxides have attracted great attention as advanced anode materials for lithium-ion batteries due to their high theoretical capacity and superior ***,the limited resource availability has led to a substantial rise in prices for valuable metals such as Ni and Co,posing a significant challenge for their *** address this issue,recycling of these metals from waste materials have gained prominence,and particularly the recovery of Co has been mostly focused on its economic ***,we introduced a novel recycling strategy for fabrication of heteroatomdoped CoO_(x)(comprising mainly Co_(3)O_(4)with a minor CoO phase)anode with a yolk–shell structure for lithium-ion batteries,by separating Co from cemented tungsten carbide *** employing a simple leaching process and subsequent spray pyrolysis,the yolk–shell structured microsphere comprising CoO_(x)was successfully ***,the presence of other waste metals in the leachate facilitated multi-heteroatom doping during ***,the introduction of various dopants into CoO_(x)induced oxygen vacancy formation,thereby enhancing the electrochemical properties of the CoO_(x)*** a result,compared with the phase-pure(undoped)CoO_(x)yolk–shell,the heteroatom-doped CoO_(x)yolk–shell exhibited robust cycling stability(602 mAh·g^(-1)for 200 cycles at 1 A·g^(-1))and excellent rate capability(210 mAh·g^(-1)at 10 A·g^(-1)).

关键词： Recycling Heteroatom doping Cobalt oxide Anode Lithium-ion batteries

Parasitic Robot System for Waypoint Navigation of Turtle

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Journal of Bionic Engineering 2017年第2期14卷 327-335页

作者： Dae-Gun kim Serin Lee Cheol-Hu kim Sungho Jo Phill-seung Lee Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) 373-1 Guseong-dong Yuseong-gu Daejeon 34141 Republic of Korea Institute for Infocomm Research 1 Fusionopolis Way #21-01 Connexis Singapore Department of Computer Science Korea Advanced Institute of Science and Technology (KAIST) 373-1 Guseong-dong Yuseong-gu Daejeon 34141 Republic of Korea

In research on small mobile robots and biomimetic robots, locomotion ability remains a major issue despite many advances in technology. However, evolution has led to there being many real animals capable of exceUent locomotion. This paper presents a ＂parasitic robot system＂ whereby locomotion abilities of an animal are applied to a robot task. We chose a turtle as our first host animal and designed a parasitic robot that can perform ＂operant conditioning＂. The parasitic robot, which is attached to the turtle, can induce object-tracking behavior of the turtle toward a Light Emitting Diode （LED） and positively reinforce the behavior through repeated stimulus-response interaction. After training sessions over five weeks, the robot could successfully control the direction of movement of the trained turtles in the waypoint navigation task. This hybrid animal-robot interaction system could provide an alternative solution to some of the limitations of conventional mobile robot systems in various fields, and could also act as a useful interaction system for the behavioral sciences.

关键词： parasitic robot operant conditioning waypoint navigation red-eared slider trachemys scripta elegans

Development of RuS_(2) for near-infrared photodetector by atomic layer deposition and post-sulfurization

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Rare Metals 2022年第9期41卷 3086-3099页

作者： Tatsuya Nakazawa Donghyun kim Jaehyeok kim Yohei Kotsugi Taehoon Cheon seung-Min Chung Soo-Hyun kim Hyungjun kim School of Electrical and Electronic Engineering Yonsei UniversitySeoul03722Korea Isehara Technical Center Metallic Materials Development DepartmentTANAKA Kikinzoku Kogyo K.KIseharaKanagawa259-1146Japan Institute of Materials Technology Yeungnam UniversityGyeongsan-si38541GyeongbukKorea Chemical Materials Development Department TANAKA Kikinzoku Kogyo K.KTsukuba Technical CenterIbaraki300-4247Japan School of Materials Science and Engineering Yeungnam UniversityGyeongsan-si38541GyeongbukKorea Center for Core Research Facilities Daegu Gyeongbuk Institute of Science&TechnologyDaegu711-873Korea

The chalcogenides of platinum-group metals(PGMs)have been known to be present in minerals and the intermediate products of *** recent years,their applications in various fields,including catalysis,have been *** that certain PGM chalcogenides behave as compound semiconductors,they can be used as materials for *** this study,RuS_(2),featuring a bandgap suitable for near-infrared photodetectors,was prepared by forming Ru on a SiO_(2)/Si substrate via the atomic layer deposition method using[Ru(TMM)(CO)_(3)]as the *** was conducted at 800℃ for 1 h under H_(2)S ***-resolution transmission electron microscopy(HRTEM)and X-ray diffraction(XRD)analysis clearly confirmed that the as-deposited hexagonal close-packed(hcp)Ru transformed to cubic RuS_(2) after *** surface morphologies,chemical states,and electrical and optical properties of RuS_(2) were *** influence of the metallic Ru surface morphology prior to sulfurization on the reaction between Ru and H_(2)S was also *** evaluate the potential of using RuS_(2) as a photodetector,a photodetector was fabricated by forming electrodes on RuS_(2) to measure its photocurrent under near-infrared ***,RuS_(2) was proven to exhibit a short response time(59μs)and generate a photocurrent of 84 nA under near-infrared light at 940 nm.

关键词： RuS_(2) Sulfurization Atomic layer deposition Photodetector

Effect of SiC particles on microstructure and mechanical property of friction stir processed AA6061-T4

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中国有色金属学会会刊：英文版 2012年第S3期22卷 614-618页

作者： Don-Hyun CHOI Yong-Il kim DAE-Up kim seung-Boo JUNG School of Advanced Materials Science and Engineering Sungkyunkwan University MEPL Sungkyunkwan University KITECH 838-11Palbok-dong 2-gaDeokjin-guJeonju-cityJeollabuk-do 561-844Korea

Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried *** particles were uniformly dispersed into an AA6061-T4 *** SiC particles promoted the grain refinement of the AA6061-T4 matrix by *** mean grain size of the stir zone (SZ) with the SiC particles was obviously smaller than that of the stir zone without the SiC *** microhardness of the SZ with the SiC particles reached about HV80 due to the grain refinement and the distribution of the SiC particles.

关键词： friction stir processing AA6061-T4 SiC particles pinning effect

Combination could be another tool for bowel preparation?

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World Journal of Gastroenterology 2016年第10期22卷 2915-2921页

作者： Jae seung Soh Kyung-Jo kim Division of Gastroenterology Department of Internal MedicineHallym University Sacred Heart HospitalUniversity of Hallym College of Medicine Department of Gastroenterology Asan Medical CenterUniversity of Ulsan College of Medicine

Optimal bowel preparation increases the cecal intubation rate and detection of neoplastic lesions while decreasing the procedural time and procedural-related complications. Although high-volume polyethylene glycol(PEG) solution is the most frequently used preparation for bowel cleansing, patients are often unwilling to take PEG solution due to its large volume, poor palatability, and high incidence of adverse events, such as abdominal bloating and nausea. Other purgatives include osmotic agents(e.g., sodium phosphate, magnesium citrate, and sodium sulfate), stimulant agents(e.g., senna, bisacodyl, and sodium picosulfate), and prokinetic agents(e.g., cisapride, mosapride, and itopride). A combination of PEG with an osmotic, stimulant, or prokinetic agent could effectively reduce the PEG solution volume and increase patients' adherence. Some such solutions have been found in several published studies to not be inferior to PEG alone in terms of bowel cleansing quality. Although combination methods showed similar efficacy and safety, the value of these studies is limited by shortcomings in study design. New effective and well-tolerated combination preparations are required, in addition to rigorous new validated studies.

关键词： Bowel preparation Colonoscopy Inadequate bowel cleansing Combination methods Intolerance

On the global existence of weak solutions for the Cucker-Smale-Navier-Stokes system with shear thickening

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Science China Mathematics 2018年第11期61卷 2033-2052页

作者： seung-Yeal Ha Hwa Kil kim Jae-Myoung kim Jinyeong Park Department of Mathematical Sciences and Research Institute of Mathematics Seoul National University Seoul 08826 Republic of Korea Korea Institute for Advanced Study Seoul 02455 Republic of Korea Department of Mathematics Education Hannam University Daejeon 34430 Republic of Korea Department of Mathematical Sciences Seoul National University Seoul 08826 Republic of Korea Department of Mathematics and Research Institute of Natural Sciences Hanyang University Seoul 04763 Republic of Korea

We study the large-time dynamics of Cucker-Smale(C-S)flocking particles interacting with nonNewtonian incompressible *** of particles and fluids were modeled using the kinetic Cucker-Smale equation for particles and non-Newtonian Navier-Stokes system for fluids,respectively and these two systems are coupled via the drag force,which is the main flocking(alignment)mechanism between particles and *** present a global existence theory for weak solutions to the coupled Cucker-Smale-Navier-Stokes system with shear *** also use a Lyapunov functional approach to show that sufficiently regular solutions approach flocking states exponentially fast in time.

关键词： emergence flocking Cucker-Smale model Navier-Stokes equation non-Newtonian fluid

Rapid determination of lithium-ion battery degradation: High C-rate LAM and calculated limiting LLI

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Journal of Energy Chemistry 2022年第4期31卷 663-671页

作者： Gyuwon Seo Jaeyun Ha Moonsu kim Jihyeon Park Jaewon Lee Eunoak Park Sungyool Bong Kiyoung Lee Soon jong Kwon seung-pil Moon Jinsub Choi Jaeyoung Lee Electrochemical Reaction and Technology Laboratory School of Earth Sciences and Environmental EngineeringGwangju Institute of Science and Technology(GIST)Gwangju 61005South Korea Department of Chemistry and Chemical Engineering Inha UniversityIncheon 22212South Korea Ertl Center for Electrochemistry and Catalysis GISTGwangju 61005South Korea Korea Electric Power Corporation Research Institute Daejeon 34056South Korea International Future Research Center of Chemical Energy Storage and Conversion Processes(ifRC-CHESS) GISTGwangju 61005South Korea

Herein,incremental capacity-differential voltage (IC-DV) at a high C-rate (HC) is used as a non-invasive diagnostic tool in lithium-ion batteries,which inevitably exhibit capacity fading caused by multiple mechanisms during charge/discharge *** battery degradation modes are complex,the simple output of capacity fading does not yield any useful data in that *** IC and DV curves obtained under restricted conditions (<0.1C,25℃) were applied in non-invasive analysis for accurate observation of degradation symptoms,a facile,rapid diagnostic approach without intricate,complex calculations is critical in on-board ***,Li Ni_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC532)/graphite pouch cells were cycled at 4 and 6C and the degradation characteristics,i.e.,loss of active materials (LAM) and loss of lithium inventory (LLI),were parameterized using the IC-DV *** the incremental current cycling,the initial steep LAM and LLI slopes underwent gradual transitions to gentle states and revealed the gap between low-and high-current measurements.A quantitative comparison of LAM at high and low C-rate showed that a IC;revealed the relative amount of available reaction region limited by cell ***,this did not provide a direct relationship for estimating the LAM at a low ***,the limiting LLI,which is calculated at a C-rate approaching 0,was obtained by extrapolating the LLI through more than two points measured at high C-rate,and therefore,the LLI at 0.1C was accurately determined using rapid cycling.

关键词： Battery degradation Rapid degradation diagnosis Loss of active materials(LAM) Loss of lithium inventory(LLI) Incremental capacity(IC) Differential voltage(DV)

An effective method to generate controllable levels of ROS for the enhancement of HUVEC proliferation using a chlorin e6-immobilized PET film as a photo-functional biomaterial

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Regenerative Biomaterials 2021年第2期8卷 94-103页

作者： seung Hee Hong Min-Ah Koo Mi Hee Lee Gyeung Mi Seon Ye Jin Park HaKyeong Jeong Dohyun kim jong-Chul Park Cellbiocontrol Laboratory Department of Medical Engineering Department of Medical Engineering Graduate School of Medical ScienceBrain Korea 21 Project Department of Medical Device Engineering and Management Yonsei UniversityCollege of MedicineSeoul 03722Republic of Korea

Reactive oxygen species(ROS)are byproducts of cellular metabolism;they play a significant role as secondary messengers in cell *** cells,high concentrations of ROS induce apoptosis,senescence,and contact inhibition,while low concentrations of ROS result in angiogenesis,proliferation,and cytoskeleton ***,controlling ROS generation is an important factor in cell *** designed a chlorin e6(Ce6)-immobilized polyethylene terephthalate(PET)film(Ce6-PET)to produce extracellular ROS under red-light *** application of Ce6-PET films can regulate the generation of ROS by altering the intensity of light-emitting diode *** confirmed that the Ce6-PET film could effectively promote cell growth under irradiation at 500 μW/cm^(2) for 30 min in human umbilical vein endothelial *** also found that the Ce6-PET film is more efficient in generating ROS than a Ce6-incorporated polyurethane film under the same ***6-PET fabrication shows promise for improving the localized delivery of extracellular ROS and regulating ROS formation through the optimization of irradiation intensity.

关键词： reactive oxygen species chlorin e6 dopamine covalent bond HUVEC proliferation