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Laser micromachining of CNT/Fe/Al_2O_3 nanocomposites

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中国有色金属学会会刊：英文版 2009年第B09期19卷 189-193页

作者： Kwang-Ryul KIM Byoung-Deog ChoI Jun-Sin YI Sung-Hak Cho yong-ho choa Dong-Soo SHIN Dong-ho BAE Myung-Chang KANG Young-Keun JEONG School of Information and Communication Engineering Sungkyunkwan University Korea Institute of Machinery and Materials Department of Chemical Engineering Hanyang University NANOBASE Inc. School of Mechanical Engineering Sungkyunkwan University National Core Research Center for Hybrid Materials Solution Pusan National University

CNT/Fe/Al2O3 mixed powders were synthesized from Fe/Al2O3 nanopowders using thermal CVD for the homogeneous dispersion of carbon nanotubes CNTs. CNTs consisted of MWNT, and the diameter was approximately 20-30 nm. After sintering, CNTs were homogenously located throughout Al2O3 grain boundary and were buckled. A femto-second laser installed with special optical systems was used for micromachining of the nanocomposites. The relationship between material ablation rate and energy fluence was theoretically investigated and compared with experimental results from cross-sectional SEM analysis. The nanocomposites which have higher content of CNT show a fairly good machining result due to its higher thermal conductivity and smaller grain size as well as lower light transmittance.

关键词：纳米复合材料激光光学系统热化学气相沉积碳纳米管 Al2O3 扫描电镜分析均匀分散纳米粉体

Defect Detection of Steel Surface Using Deep Learning Based on Faster R-CNN

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Defect Detection of Steel Surface Using Deep Learning Based ...

作者： Tan Abraham choa（蔡松錢）华南理工大学

学位级别：硕士

Due to increasing demand of better surface quality in steel manufacturing,defect detection has been become challenging subject in the field of computer vision *** and accurate detection of defect plays an important role in order to control and improve the quality of the final *** with manual inspection method and machine learning method,the deep learning is more robust,which does not need human contact inspection and manually extracted features *** the advent of deep learning,the machine learning systems are able to recognize and classify objects of interest in an *** are capable of extracting feature detection process automatically from large amounts of tagged training *** work special interest in applying bounding box regression around the defected area of steel surface and classify each class of those *** order to achieve better performance,image enhancement is done by adopting laplacian operator in preprocessing step before performing deep ***,center loss is added to the original loss function to improve the network’s ability to distinguish different types of *** the proposed method,Faster R-CNN adopted AlexNet architecture as backbone for feature *** detection and recognition results can be used to adjust the production line and improved surface quality in steel *** experiment results show that the proposed method can be implemented to detect the defected area of the steel surface by making the prediction of the bounding box and classify the defected surface more *** addition,the experiment results show that the proposed algorithm could precisely predict the bounding box on the defect surface such as scratches,patches and inclusion defects.

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Visual Object Tracking Using Color and Texture Features Based on Mean-shift and Particle-kalman Filter Algorithm

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Visual Object Tracking Using Color and Texture Features Base...

作者： Tan William choa（蔡松燃）华南理工大学

学位级别：硕士

Due to increasing demand of video surveillance system,intelligent video surveillance system has become challenging subject in the field of computer vision *** intelligent video surveillance system there are four key steps,*** detection,object classification,object tracking,and object *** these steps,object tracking is considered to be a key and important task in intelligent video surveillance *** tracking is considered as difficult task because of several problems such as illumination variation,tracking non-rigid object,non-linear motion,occlusion,and requirement of real-time *** single algorithm in visual object tracking always has advantages and *** with only a single algorithm is therefore generally considered to be inadequate and inefficient because each individual algorithm has its *** Mean Shift tracking algorithm always suffers from large position errors,which may lead to the failure on tracking target in complex *** handle this problem,an improved Mean-shift Particle-Kalman Filter tracking algorithm based on texture and color features is *** the proposed method,a color feature based Mean-shift is used as the main tracking algorithm when the target-object is moving in linear motion or when there is no occlusion ***,when occlusion occurs or when the target-object is moving in non-linear motion,color and texture features fusion based Particle-Kalman Filter tracking algorithm is used as main tracking *** experiment results show that the proposed method can be implemented in single object tracking and able to cope with several tracking problems such as illumination variation,non-rigid deformation,non-linear movement,similar color interference,and ***,the experiment results show that the proposed tracking algorithm which utilizes multi features（color and texture features）to represent the target model has better perf

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High-Performance Magnetic-core Coils for Targeted Rodent Brain Stimulations

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Biomedical Engineering Frontiers 2022年第1期3卷 82-92页

作者： Hedyeh Bagherzadeh Qinglei Meng Hanbing Lu Elliott hong Yihong Yang Fow-Sen choa Department of Computer Science and Electrical Engineering University of MarylandBaltimore CountyBaltimoreMD 21250USA Neuroimaging Research Branch National Institute on Drug AbuseNational Institutes of HealthBaltimoreMD 21224USA Maryland Psychiatric Research Center Department of PsychiatryUniversity of Maryland School of MedicineBaltimoreMD 21201USA

Objective and Impact *** is a need to develop rodent coils capable of targeted brain stimulation for treating neuropsychiatric disorders and understanding brain *** describe a novel rodent coil design to improve the focality for targeted stimulations in small rodent *** magnetic stimulation(TMS)is becoming increasingly important for treating neuropsychiatric disorders and understanding brain *** studies permit invasive manipulations and are essential for the mechanistic understanding of TMS effects and explorations of therapeutic outcomes in disease ***,existing TMS tools lack focality for targeted ***,there has been limited fundamental research on developing coils capable of focal stimulation at deep brain regions on small animals like *** this study,ferromagnetic cores are added to a novel angle-tuned coil design to enhance the coil performance regarding penetration depth and *** simulations and experimental electric field measurements were conducted to optimize the coil *** proposed coil system demonstrated a significantly smaller stimulation spot size and enhanced electric field decay rate in comparison to existing *** the ferromagnetic core reduces the energy requirements up to 60%for rodent brain *** simulated results are validated with experimental measurements and demonstration of suprathreshold rodent limb excitation through targeted motor cortex *** newly developed coils are suitable tools for focal stimulations of the rodent brain due to their smaller stimulation spot size and improved electric field decay rate.

关键词： stimulation manipulation becoming

Easy calibration method of vision system for in-situ measurement of strain of thin films

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中国有色金属学会会刊：英文版 2009年第B09期19卷 243-249页

作者： Jun-Hyub PARK Dong-Joong KANG Myung-Soo SHIN Sung-Jo LIM Son-Cheol YU Kwang-Soo LEE Jong-Eun HA Sung-hoon choa Department of Mechatronics Engineering Tongmyong University School of Mechanical Engineering Pusan National University Department of Automotive Engineering Hoseo University Department of Automotive Engineering Seoul National University of Technology Department of Nano/IT Engineering Seoul N ational University of Technology

An easy calibration method was presented for in-situ measurement of displacement in the order of nanometer during micro-tensile test for thin films by using CCD camera as a sensing device. The calibration of the sensing camera in the system is a central element part to measure displacement in the order of nanometer using images taken with the camera. This was accomplished by modeling the optical projection through the camera lens and relative locations between the object and camera in 3D space. A set of known 3D points on a plane where the film is located on is projected to an image plane as input data. These points, known as a calibration points, are then used to estimate the projection parameters of the camera. In the measurement system of the micro-scale by CCD camera, the calibration data acquisition and one-to-one matching steps between the image and 3D planes need precise data extraction procedures and repetitive user's operation to calibrate the measuring devices. The lack of the robust image feature extraction and easy matching prevent the practical use of these methods. A data selection method was proposed to overcome these limitations and offer an easy and convenient calibration of a vision system that has the CCD camera and the 3D reference plane with calibration marks of circular type on the surface of the plane. The method minimizes the user's intervention such as the fine tuning of illumination system and provides an efficient calibration method of the vision system for in-situ axial displacement measurement of the micro-tensile materials.

关键词：标定方法视觉系统原位测试应变薄膜松

Fish-on-Chips:unveiling neural processing of chemicals in small animals through precise fluidic control

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Neural Regeneration Research 2024年第11期19卷 2351-2353页

作者： Samuel K.H.Sy ho Ko Division of Neurology Department of Medicine and TherapeuticsFaculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Li Ka Shing Institute of Health Sciences Faculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Department of Electrical and Electronic Engineering Faculty of EngineeringThe University of Hong KongPok Fu LamHong Kong IslandHong Kong Special Administrative RegionChina Advanced Biomedical Instrumentation Center Hong Kong Science ParkPak Shek KokNew TerritoriesHong Kong Special Administrative RegionChina Margaret K.L.Cheung Research Center for Management of Parkinsonism Faculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Lau Tat-chuen Research Center of Brain Degenerative Diseases in Chinese Faculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Gerald choa Neuroscience Institute The Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina

Precise chemical cue presentation alongside advanced brainwide imaging techniques is important to the study of chemosensory processing in ***,the dynamic nature of chemical-carrying media,such as water or air,poses a significant challenge for delivering highly-controlled chemical flow to an animal ***,contact-based cue manipulation and delivery easily shift the position of the animal subject,which is often undesirable for high-quality brain ***,more advanced interfacing tools that align with the diverse range of body part sizes of an animal,ranging from micrometer-scale neurons to meter-long limbs,are much *** is particularly crucial when dealing with dimensions that are beyond the reach of conventional experimental tools.

关键词： dealing precise sizes

Transcriptional dysregulation in neurodegenerative diseases:who tipped the balance of Yin Yang 1 in the brain?

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Neural Regeneration Research 2019年第7期14卷 1148-1151页

作者： Zhefan Stephen Chen ho Yin Edwin Chan School of Life Sciences Faculty of ScienceThe Chinese University of Hong Kong Gerald choa Neuroscience Centre The Chinese University of Hong Kong

Yin Yang 1(YY1) is a multi-functional transcription factor that regulates gene expression in a range of cell types,including *** controls neuronal differentiation,as well as neuronal specification and migration during the development of the mammalian nervous ***,YY1 also mediates the transcription of genes that are required for neuronal *** impairment of the transcriptional function of YY1 causes neuronal *** review summarizes recent research findings that unveil the dysfunction of YY1 in multiple neurodegenerative *** expression of disease proteins perturbs the function of YY1 via distinct molecular mechanisms,including recruitment to protein aggregates,protein degradation and aberrant nuclear/cytoplasmic *** the pathogenic roles of YY1 will further broaden our knowledge of the disease mechanisms in distinct neurodegenerative disorders.

关键词： Alzheimer’s disease amyotrophic lateral sclerosis neurodegeneration protein aggregates recruitment protein degradation subcellular localization transcriptional regulation Yin Yang 1

紫外线/臭氧处理对喷墨印刷铜图文和聚酰亚胺基材间相互作用的影响

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中国印刷与包装研究 2013年第1期5卷 71-75页

作者： LEE Young-In GOO yong-Sung LEE Kun-Jae HWANG Yun-Gu BYUN Younghun PARK Hee Jung PARK Deok-yong MYUNG Nosang V choa yong-ho 何文 Department of Fine Chemical Engineering Hanyang University Ansan 426 -791 Republic of Korea Advanced MaterialsLaboratory Samsung Advanced Institute of Technology Yongin 446-712 Republic of Korea Materials Research Laboratory AdvancedInstitute of Technology Yongin 446 - 712 Republic of Korea Department of Applied Materials Engineering Hanbat National University Daejeon 305 -719 Republic of Korea Department of Chemical and Environmental Engineering and Center forNanoscale Science and Engineering Univcrsity of California-Riverside Riverside CA 92521 USA 不详

摘译近年来,喷墨印刷电子技术得到了迅速发展,因为相对于传统光刻技术需要通过真空处理、化学沉积和蚀刻来制作电路图案,喷墨印刷更简单、经济。目前,喷墨印刷已用于制作各种灵巧的电子器件,如薄膜晶体管、射频识别标签、印刷电路板等。

关键词：喷墨印刷相互作用聚酰亚胺紫外线印刷电路板基材图文臭氧

Electricity Derived from Plants

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Journal of Energy and Power Engineering 2017年第9期11卷 614-619页

作者： Mohammad Islam Douglas Janssen David Chao Jerry Gu David Eisen Fow-Sen choa Department of CSEE University of Maryland Baltimore County Baltimor 21250 Maryland USA Greater Grace Christian Academy 6063 Moravia Park Drive Baltimore 21206 Maryland USA Department of Biological Science National Sun Yat-Sun University Kao-shiun Taiwan ROC

The phenomenon of electrical potential differences along the plant apoplast has been reported for more than a century. Earlier works of harvesting energy from trees reported nW range of power with a few hundred-mV open circuit voltage and near uA range short circuit current. In this work, we show that if we cut a stem into pieces, each segment would maintain nearly the same open circuit voltage and short circuit current regardless of length. Using a pico-ampere meter, we also found that the living cells in the vascular cambial and secondary xylem and phloem tissues are the source of electricity. They provide a relatively constant voltage and current to external environment for reasons still under investigation. We demonstrate that by cascading separated stems we can accumulate up to 2 V of open circuit voltage. We also demonstrate by connecting them in parallel we can increase the short circuit current.

关键词： Plants cell electricity electrophysiology ion gates parallel circuits.