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Feedback Control of an Achiral Robotic Microswimmer

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Journal of Bionic Engineering 2017年第2期14卷 245-259页

作者： U Kei Cheang Hoyeon kim Dejan Milutinovic Jongeun Choi min jun kim Department of Mechanical Engineering and Mechanics Drexel University Philadelphia PA 19104 USA Department of Mechanical Engineering Southern Methodist University Dallas TX75275 USA Department of Computer Engineering University of California Santa Cruz Santa Cruz California 95064 USA School of Mechanical Engineering Yonsei University Seoul South Korea

Magnetic microswimmers are useful for navigating and performing tasks at small scales. To demonstrate effective control over such microswimmers, we implemented feedback control of the three-bead achiral microswimmers in both simulation and experiment. The achiral microswimmers with the ability to swim in bulk fluid are controlled wirelessly using magnetic fields generated from electromagnetic coils. The achirality of the microswimmers introduces unknown handedness resulting in uncertainty in swimming direction. We use a combination of rotating and static magnetic fields generated from an approximate Helmholtz coil system to overcome such uncertainty. There are also movement uncertainties due to environmental factors such as unsteady flow conditions. A kinematic model based feedback controller was created based on data fitting of experimental data. However, the controller was unable to yield satisfactory performance due to uncertainties from environmental factors; i.e., the time to reach target pose under adverse flow condition is too long. Following the implementation of an integral controller to control the microswimmers＇ swimming velocity, the mieroswimmers were able to reach the target in roughly half the time. Through simulation and experiments, we show that the feedback control law can move an achiral microswimmer from any initial conditions to a target pose.

关键词： microrobotics magnetic control low Reynold number chirality feedback control

Characterization of Deciliation-Regeneration Process of Tetrahymena Pyriformis for Cellular Robot Fabrication

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Journal of Bionic Engineering 2011年第3期8卷 273-279页

作者： Dal Hyung kim Sean E. Brigandi Paul kim Doyoung Byun min jun kim Department of Mechanical Engineering & Mechanics Drexel University Philadelphia PA 19104 USA Department of Aerospace Information Engineering Konkuk University Seoul 143-701 South Korea

magnetotactic Tetrahymena pyriformis GL （T. pyriformis） cells were created by the internalization of iron oxide nano particles and became controllable with a time-varying external magnetic field. Thus, T. pyriformis can be utilized as a cellular robot to conduct micro-scale tasks such as transportation and manipulation. To complete these tasks, loading inorganic or organic materials onto the cell body is essential, but functionalization of the cell membrane is obstructed by their motile organelles, cilia. Dibucaine HC1, a local anesthetic, removes the cilia from the cell body, and the functional group would be absorbed more efficiently during cilia regeneration. In this paper, we characterize the recovery of artificial magnetotactic T. pyriformis after the deciliation process to optimize a cellular robot fabrication process. After sufficient time to recover, the motility rate and the average velocity of the deciliated cells were six and ten percent lower than that of non-deciliated cells, respectively. We showed that the motile cells after recovery can still be controlled using magnetotaxis, making T. pyrfformis a good candidate to be used as a celIular robot.

关键词： Tetrahymena pyriformis deciliation cellular robot Helmholtz coil magnetic field magnetotaxis

Materials and devices for flexible and stretchable photodetectors and light-emitting diodes

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Nano Research 2021年第9期14卷 2919-2937页

作者： jun-Kyul Song min Sung kim Seungwon Yoo Ja Hoon Koo Dae-Hyeong kim Center for Nanoparticle Research Institute for Basic Science(IBS)Seoul 08826Republic of Korea School of Chemical and Biological Engineering and Institute of Chemical Processes Seoul National UniversitySeoul 08826Republic of Korea Interdisciplinary Program for Bioengineering Seoul National UniversitySeoul 08826Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea

Recently,significant efforts have been directed at overcoming the limitations of conventional rigid optoelectronic devices,particularly their poor mechanical stability under bending,folding,and stretching *** of major approaches for rendering optoelectronic devices mechanically deformable is to replace the conventional electronic/optoelectronic materials with functional nanomaterials or organic materials that are intrinsically flexible/***,advanced device designs and unconventional fabrication methods have also contributed to the development of soft optoelectronic ***,new devices such as bio-inspired curved image sensors,wearable light emitting devices,and deformable bio-integrated optoelectronic devices have been *** this review,recent progress in the development of soft optoelectronic materials and devices is ***,various materials such as nanomaterials,organic materials,and their hybrids that are suitable for developing deformable photodetectors,are ***,the nanomaterials and organic/polymeric materials that are applicable in deformable light-emitting diodes are ***,representative system-level applications of flexible and stretchable photodetectors and light-emitting diodes are reviewed,and future prospects are discussed.

关键词： nanomaterial organic material photodetector light-emitting diode flexible optoelectronics stretchable optoelectronics

Obturator hernia-a rare etiology of lateral thigh pain:A case report

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World Journal of Clinical Cases 2021年第34期9卷 10728-10732页

作者： jun Young kim min Cheol Chang Department of Physical Medicine and Rehabilitation College of MedicineYeungnam UniversityTaegu 705-717South Korea

BACKGROUND Lateral thigh pain is a common complaint in patients visiting a pain ***,we describe the case of a patient with lateral thigh pain caused by an obturator *** SUMMARY An 83-year-old woman visited the emergency room with suddenly aggravated right lateral thigh *** resonance imaging of the thigh revealed no abnormal findings in the lateral thigh ***,an obturator hernia between the pectineus and obturator externus muscles was observed by *** computed tomography revealed a herniated small bowel with an incarceration point at the right obturator canal and a dilated loop of the small bowel *** of the right inguinal region revealed a distended bowel loop in the right pectineus *** Our report provides clinicians with information that an obturator hernia can cause lateral thigh pain.

关键词： Obturator hernia Pain Magnetic resonance image Computed tomography Ultrasonography Case report

Performance evaluation of the use of tire-derived fuel fly ash as mineral filler in hot mix asphalt concrete

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Journal of Traffic and Transportation Engineering(English Edition) 2020年第2期7卷 249-258页

作者： min Ju Choi Yong Joo kim Hyeok jung kim Jae jun Lee BILTZONE Co. Ltd.Hwaseong 18514South Korea Korea Institute o f Civil Engineering and Building Technology Goyang-Si 10223South Korea Industry-Academic Cooperation Foundation Center Hankyong National UniversityAnseong-si 17579South Korea Department of Civil Engineering Chonbuk National UniversityJeonju 54896South Korea

According to deplete natural resources and need to protect the environment,the demand of a usage of waste material has significantly *** studies are currently being carried out on the development of innovative and environmentally friendly materials for securing the safety of road users and improving the performance and durability of *** example,studies are currently being conducted on the use of waste tires as a substitute for currently used *** the development of the automobile industry,the amount of waste tire has continuously increased in accordance with the increased vehicle ***-derived fuel(TDF)has been used as a fuel source with generated TDF fly *** filler,made of fine mineral particles of a physical size passing the number 200 standard mesh sieve(75 micron),plays an important role in asphalt mixtures *** paper presents an application of TDF fly ash as filler in hot mix asphalt(HMA).In this study,the performance of TDF fly ash was confirmed through a comparison with three other mineral fillers:stone dust,cement,and hydrated *** tests including Marshall stability test,moisture sensitivity test,dynamic immersion test,and a wheel tracking test were performed to investigate the difference in the behaviors of the samples with different parameters considered in this *** results show that the mechanical performance of hot mix asphalt using TDF fly ash satisfied the quality standard specification of the ministry of Land,Infrastructure and Transport(MOLIT),*** can be concluded that the use of TDF fly ash as a mineral filler in HMA not only satisfied the mechanical properties,but also reduced the volume of the pollutants waste in the environment.

关键词： Asphalt mixture TDF fly ash Marshal stability Moisture sensitive TSR

Left or Right Hand Classification from Fingerprint Images Using a Deep Neural Network

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Computers, Materials & Continua 2020年第4期63卷 17-30页

作者： junseob kim Beanbonyka Rim Nak-jun Sung min Hong Department of Computer Science Soonchunhyang University31538AsanKorea Department of Computer Software Engineering Soonchunhyang University31538AsanKorea

Fingerprint security technology has attracted a great deal of attention in recent years because of its unique biometric information that does not change over an individual’s lifetime and is a highly reliable and secure way to identify a certain ***(Automated Fingerprint Identification System)is a system used by Korean police for identifying a specific person by *** AFIS system,however,only selects a list of possible candidates through fingerprints,the exact individual must be found by fingerprint *** this paper,we designed a deep learning system using deep convolution network to categorize fingerprints as coming from either the left or right *** this paper,we applied the Classic CNN(Convolutional Neural Network),AlexNet,Resnet50(Residual Network),VGG-16,and YOLO(You Only Look Once)networks to this problem,these are deep learning architectures that have been widely used in image analysis *** used total 9,080 fingerprint images for training and 1,000 fingerprint to test the performance of the proposed *** a result of our tests,we found the ResNet50 network performed the best at determining if an input fingerprint image came from the left or right hand with an accuracy of 96.80%.

关键词： Deep Learning convolution neural network fingerprint classification

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文档级神经机器翻译综述

软件学报 2025年第1期36卷 152-183页

作者：吕星林李军辉陶仕敏杨浩张民苏州大学计算机科学与技术学院华为翻译中心

机器翻译(machine translation, MT)研究旨在构建一个自动转换系统,将给定源语言序列自动地转换为具有相同语义的目标语言序列.由于机器翻译广阔的应用场景,使其成为自然语言理解领域乃至人工智能领域的一个重要的研究方向.近年来,端到... 详细信息

机器翻译(machine translation, MT)研究旨在构建一个自动转换系统,将给定源语言序列自动地转换为具有相同语义的目标语言序列.由于机器翻译广阔的应用场景,使其成为自然语言理解领域乃至人工智能领域的一个重要的研究方向.近年来,端到端的神经机器翻译(neural machine translation, NMT)方法显著超越了统计机器翻译(statistical machine translation, SMT)方法,成为目前机器翻译研究的主流方法.然而,神经机器翻译系统通常以句子为翻译单位,在面向文档的翻译场景中,将文档中每个句子独立地进行翻译,会因脱离文档的篇章语境引起一些篇章级的错误,如词语错翻、句子间不连贯等.因此将文档级的信息融入到翻译的过程中去解决跨句的篇章级错误是更加自然和合理的做法,文档级的神经机器翻译(document-level neural machine translation, DNMT)的目标正是如此,成为机器翻译研究的热门方向.调研了近年来在文档级神经机器翻译研究方向的主要工作,从篇章评测方法、使用的数据集和模型方法等方面系统地对当前研究工作进行了归纳与阐述,目的是帮助研究者们快速了解文档级神经机器翻译研究现状以及未来的发展和研究方向.同时在文中也阐述了在文档级神经机器翻译的一些展望、困难和挑战,希望能带给研究者们一些启发.

关键词：神经机器翻译 Transformer模型文档上下文篇章评测

Microstructural characteristics and low-cycle fatigue properties of AZ91 and AZ91-Ca-Y alloys extruded at different temperatures

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Journal of Magnesium and Alloys 2023年第3期11卷 892-902页

作者： Ye Jin kim Young min kim jun Ho Bae Soo-Hyun Joo Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Dankook UniversityCheonan 31116Republic of Korea

The commercial AZ91 alloy and nonflammable SEN9(AZ91-0.3Ca-0.2Y,wt%)alloy are extruded at 300°C and 400°*** microstructure,tensile and compressive properties,and low-cycle fatigue(LCF)properties are investigated,with particular focus on the influence of the extrusion *** the AZ91 and SEN9 materials extruded at 300°C(300-materials),numerous fine Mg_(17)Al_(12)particles are inhomogeneously distributed owing to localized dynamic precipitation during extrusion,unlike those extruded at 400°C(400-materials).These fine particles suppress the coarsening of recrystallized grains,decreasing the average grain size of *** the four extruded materials have considerably different microstructures,the difference in their tensile yield strengths is insignificant because strong grain-boundary hardening and precipitation hardening effects in 300-materials are offset almost completely by a strong texture hardening effect in ***,owing to their finer grains and weaker texture,300-materials have higher compressive yield strengths *** the LCF tests,{10-12}twinning is activated at lower stresses in 400-materials than in *** the fatigue damage accumulated per cycle is smaller in 400-materials,they have longer fatigue lives than those of 300-materials.A fatigue life prediction model for the investigated materials is established on the basis of the relationship between the total strain energy density(ΔW_(t))and the number of cycles to fatigue failure(N_(f)),and it is expressed through a simple equation(ΔW_(t)=10·N_(f)-0.59).This model enables fatigue life prediction of both the investigated alloys regardless of the extrusion temperature and strain amplitude.

关键词： AZ91-Ca-Y Extrusion temperature Microstructure Low-cycle fatigue Fatigue life prediction model

Controlling a lithium surface with an alkyl halide nucleophile exchange

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Journal of Energy Chemistry 2021年第11期30卷 617-626,I0015页

作者： jung-Hun Lee Thuy Hoai Linh Vuong Soo min Hwang Jae-Hun kim Young-jun kim SKKU Advanced Institute of Nanotechnology(SAINT) Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Nano Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea School of Materials Science and Engineering Kookmin UniversitySeoul 02707Republic of Korea

Despite its high theoretical energy density, lithium metal faces huge challenges in its implementation as an anode for Li secondary batteries because of its uncontrollable dendritic growth and large volume change during plating/stripping processes. These geometric changes cause degradation in a cell’s cycle life and performance and can lead to short-circuits and explosions. Here, we report a new approach to producing a LiF-rich phase on the lithium anode surface by employing a “bi-phase” separator. We fabricated it by coating polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) onto a cellulose separator. The coverage of coating was adjusted by varying its concentration in the coating solution. The combination of cellulose and PVDF-HFP produced a LiF-rich solid-electrolyte interphase layer on the Li metal surface via an alkyl halide nucleophile exchange in contact with the bi-phase separator during plating. Symmetric cell tests show that the bi-phase separator extends the cycle life by more than 300 h, with overpotentials of less than 100 mV under plating/stripping at 2 mA cm^(−2) for a capacity of 2 mAh cm^(−2). The formation mechanism of the LiF-rich phase is suggested from spectroscopic analyses.

关键词： Li metal anode PVDF-HFP Cellulose LiF Phase inversion