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Improvement of machining quality of copper-plated roll mold by controlling temperature variation

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 37-41页

作者： Tae-Jin JE Eun-Chae JEON sang-cheon park Doo-Sun CHOI Kyung-Hyun WHANG Myung-Chang KANG Division of Nano-Mechanical Systems Korea Institute of Machinery and Materials Daejeon 305-343 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

Micro prism film used in LCD industry can be manufactured by roll to roll method with copper-plated roll mold. As copper-plated roll mold is getting larger, pitch error is getting severer. The pitch error drops the quality of micro prism film. The main cause of the pitch error was investigated during machining large roll mold whose machined length was 1 200 mm. The temperature of machining system was elevated during machining roll mold, and this elevation induced thermal expansion of the system. The temperature variation around the roll mold also made thermal expansion of the roll mold. The amount of thermal expansion had strong relationship to the amount of pitch error. Therefore, the roll mold was machined after warming-up of machining system and precise temperature controller around copper-plated roll mold was installed, which minimized the temperature variation. Finally, precise micro prism patterns without pitch error were machined on the large roll mold.

关键词： copper-plated roll mold machining prism pattern temperature variation

Machining characteristics of complex prism pattern on electroplated roll by copper

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中国有色金属学会会刊：英文版 2009年第B09期19卷 288-294页

作者： Tae-Jin JE sang-cheon park Kang-Won LEE Yeong-Eun YOO Doo-Sun CHOI Kyung-Hyun WHANG Myung-Chang KANG Nano-Machining Laboratory Division of Nano-Mechanical Systems Korea Institute of Machinery and Materials Nano-Mechatronics Department University of Science and TechnologySinseongnoYouseong-GuDaejeonKorea National Core Research Center for Hybrid Materials Solution Pusan National University

The BLU (back light unit) is the core component of the LCD for notebook, mobile-phone, navigation, as well as large sized TV, PID (public information display), etc. In order to enhance optical efficiency of LCD, optical films with the uniform prism patterns have been used for BLU by stacking two films up orthogonally. In this case, light interference-phenomenon occurred such as Morie, wet-out, u-turning, etc. It caused several problems such as low brightness, spots and stripes in LCD. Recently, the high-luminance micro complex prism patterns are actively studied to avoid the light interference-phenomenon and enhance the optical efficiency. In this study, the roll master to manufacture complex micro prism pattern film was machined by using the high precision lathe. The machined patterns on the roll master were 50, 45, 40, 35, 30, 25, 20, 15, 10 and 5 μm in the pitch with 25.0, 22.5, 20.0, 17.5, 15.0, 12.5, 10.0, 7.5, 5.0 and 2.5 μm in the peak height, respectively. The roll was 2 000 mm in length and 320 mm in diameter. The electroplated roll by copper and the natural single crystal diamond tool was used for machining the patterns. The cutting force was measured and analyzed for each cutting condition by using the dynamometer. The chips and the surfaces after being machined were analyzed by SEM and microscope.

关键词：车床加工微棱镜铜电镀特征光学效率光学薄膜笔记本电脑金刚石工具

Wearable Triboelectric Nanogenerators Based on Printed Polyvinylidene Fluoride Films Incorporated with Cobalt-Based Metal-Organic Framework for Self-Powered Mobile Electronics

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Energy & Environmental Materials 2024年第4期7卷 396-403页

作者： Myeong-Hyeon Kim sang-Joon park Tae-Jun Ha Department of Electronic Materials Engineering Kwangwoon University

In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride (PVDF) films incorporated with cobalt-based metalorganic framework (Co-MOF) were *** enhanced output performance of the TENCs was attributed to the phase transition of PVDF from α-crystals to β-crystals,as facilitated by the incorporation of the MOF.

关键词： bar printing phase transition polyvinylidene fluoride incorporated with cobalt-based metal–organic framework self-powered mobile electronics wearable triboelectric nanogenerators

Enhanced prediction of anisotropic deformation behavior using machine learning with data augmentation

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Journal of Magnesium and Alloys 2024年第1期12卷 186-196页

作者： Sujeong Byun Jinyeong Yu Seho cheon Seong Ho Lee Sung Hyuk park Taekyung Lee School of Mechanical Engineering Pusan National UniversityBusan 46241South Korea School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566South Korea

Mg alloys possess an inherent plastic anisotropy owing to the selective activation of deformation mechanisms depending on the loading *** characteristic results in a diverse range of flow curves that vary with a deformation *** study proposes a novel approach for accurately predicting an anisotropic deformation behavior of wrought Mg alloys using machine learning(ML)with data *** developed model combines four key strategies from data science:learning the entire flow curves,generative adversarial networks(GAN),algorithm-driven hyperparameter tuning,and gated recurrent unit(GRU)*** proposed model,namely GAN-aided GRU,was extensively evaluated for various predictive scenarios,such as interpolation,extrapolation,and a limited dataset *** model exhibited significant predictability and improved generalizability for estimating the anisotropic compressive behavior of ZK60 Mg alloys under 11 annealing conditions and for three loading *** GAN-aided GRU results were superior to those of previous ML models and constitutive *** superior performance was attributed to hyperparameter optimization,GAN-based data augmentation,and the inherent predictivity of the GRU for *** a first attempt to employ ML techniques other than artificial neural networks,this study proposes a novel perspective on predicting the anisotropic deformation behaviors of wrought Mg alloys.

关键词： Plastic anisotropy Compression Annealing Machine learning Data augmentation

Acetylacetone-TiO2 Promoted Large Area Compatible Cascade Electron Transport Bilayer for Efficient Perovskite Solar Cells

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Energy & Environmental Materials 2024年第2期7卷 225-232页

作者： Hyong Joon Lee Jin Kyoung park Jin Hyuck Heo sang Hyuk Im Department of Chemical and Biological Engineering Korea University

In designing efficient perovskite solar cells（PSCs）,the selection of suitable electron transport layers（ETLs） is critical to the final device performance as they determine the driving force for selective charge ***2nanoparticles（NPs） based ETLs have been a popular choice for PSCs due to superior electron mobility,but their relatively deep-lying conduction band energy levels(ECB) result in substantial potential ***,TiO2NPs establish favorable band alignment owing to shallower ECB,but their low intrinsic mobility and abundant surface trap sites impede the final *** this reason,constructing a cascaded bilayer ETL is highly desirable for efficient PSCs,as it can rearrange energy levels and exploit on advantages of an individual *** this study,we prepare SnO2NPs and acetylacetone-modified TiO2（Acac-TiO2） NPs and implement them as bilayer SnO2/Acac-TiO2（BST） ETL,to assemble cascaded energy band ***2contributes to rapid charge carrier transport from high electron mobility while Acac-TiO2minimizes band-offset and effectively suppresses interfacial ***,the optimized BST ETL generates synergistic influence and delivers power conversion efficiency（PCE） as high as 23.14% with open-circuit voltage(VOC) reaching 1.14 ***,the BST ETL is transferred to a large scale and the corresponding mini module demonstrates peak performance of 18.39% PCE from 25 cm2aperture ***,the BST-based mini module exhibit excellent stability,maintaining83.1% of its initial efficiency after 1000 h under simultaneous 1 Sun lightsoaking and damp heat（85℃/RH 85%） environment.

关键词： acetylacetone large area perovskite solar cells TiO2

Cross-Domain Bilateral Access Control on Blockchain-Cloud Based Data Trading System

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 671-688页

作者： Youngho park Su Jin Shin sang Uk Shin Electronics and Information Communications Research Center Pukyong National UniversityBusan48513Republic of Korea Department of Information Security Graduate SchoolPukyong National UniversityBusan48513Republic of Korea Division of Computer Engineering Pukyong National UniversityBusan48513Republic of Korea

Data trading enables data owners and data requesters to sell and purchase *** the emergence of blockchain technology,research on blockchain-based data trading systems is receiving a lot of ***,to reduce the on-chain storage cost,a novel paradigm of blockchain and cloud fusion has been widely considered as a promising data trading ***,the fact that data can be used for commercial purposes will encourage users and organizations from various fields to participate in the data *** the data marketplace,it is a challenge how to trade the data securely outsourced to the external cloud in a way that restricts access to the data only to authorized users across multiple *** this paper,we propose a cross-domain bilateral access control protocol for blockchain-cloud based data trading *** consider a system model that consists of domain authorities,data senders,data receivers,a blockchain layer,and a cloud *** proposed protocol enables access control and source identification of the outsourced data by leveraging identity-based cryptographic *** the proposed protocol,the outsourced data of the sender is encrypted under the target receiver’s identity,and the cloud provider performs policy-match verification on the authorization tags of the sender and receiver generated by the identity-based signature ***,data trading can be achieved only if the identities of the data sender and receiver simultaneously meet the policies specified by each *** demonstrate efficiency,we evaluate the performance of the proposed protocol and compare it with existing studies.

关键词： Bilateral access control blockchain data sharing policy-match

Real-Time Tunable Gas Sensing Platform Based on SnO2 Nanoparticles Activated by Blue Micro-Light-Emitting Diodes

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Nano-Micro Letters 2024年第12期16卷 103-119页

作者： Gi Baek Nam Jung-El Ryu Tae Hoon Eom Seung Ju Kim Jun Min Suh Seungmin Lee Sungkyun Choi cheon Woo Moon Seon Ju park Soo Min Lee Byungsoo Kim Sung Hyuk park Jin Wook Yang sangjin Min Sohyeon park Sung Hwan Cho Hyuk Jin Kim sang Eon Jun Tae Hyung Lee Yeong Jae Kim Jae Young Kim Young Joon Hong Jong-In Shim Hyung-Gi Byun Yongjo park Inkyu park sang-Wan Ryu Ho Won Jang Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Research Laboratory of Electronics Department of Mechanical EngineeringMassachusetts Institute of TechnologyCambridgeMA 02139USA Ming Hsieh Department of Electrical and Computer Engineering University of Southern CaliforniaLos AngelesCA 90089USA Department of Display Materials Engineering Soonchunhyang UniversityAsan 31538Republic of Korea Department of Photonics and Nanoelectronics BK21 FOUR ERICA-ACE CenterHanyang University ERICAAnsan 15588Republic of Korea Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Electronics Information and Communication EngineeringKangwon National UniversitySamcheok 25913Republic of Korea Advance Institute of Convergence Technology Seoul National UniversitySuwon 16229Republic of Korea Department of Mechanical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Physics Chonnam National UniversityGwangju 500-757Republic of Korea

Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power ***,despite these benefits,challenges still exist such as a limited range of detectable gases and slow *** this study,we present a blueμLED-integrated light-activated gas sensor array based on SnO_(2)nanoparticles(NPs)that exhibit excellent sensitivity,tunable selectivity,and rapid detection with micro-watt level power *** optimal power forμLED is observed at the highest gas response,supported by finite-difference time-domain ***,we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO_(2)*** noble metals induce catalytic interaction with reducing gases,clearly distinguishing NH3,H2,and ***-time gas monitoring based on a fully hardwareimplemented light-activated sensing array was demonstrated,opening up new avenues for advancements in light-activated electronic nose technologies.

关键词： Micro-LED Gas sensor array Low power consumption Metal decoration Real-time detection

Validity of fatty liver prediction scores for diagnosis of fatty liver by Fibroscan

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Hepatobiliary & Pancreatic Diseases International 2024年第4期23卷 353-360页

作者： Seogsong Jeong Sun Jae park Seong Kyun Na sang Min park Byung-Cheol Song Yun Hwan Oh Department of Biomedical Sciences Seoul National University Graduate SchoolSeoul 03080Korea Department of Biomedical Informatics CHA University School of MedicineCHA UniversitySeongnam 13488Korea Department of Internal Medicine Inje University College of MedicineSeoul 50834Korea Department of Family Medicine Seoul National University HospitalSeoul National University College of MedicineSeoul 03080Korea Department of Internal Medicine Jeju National University HospitalJeju National University College of MedicineJeju 63241Korea Department of Family Medicine Jeju National University HospitalJeju National University College of MedicineJeju 63241Korea Department of Family Medicine Chung-Ang University Gwangmyeong HospitalChung-Ang University College of MedicineGwangmyeong 14353Korea

Background:The Korea National Health and Nutrition Examination Survey nonalcoholic fatty liver disease(K-NAFLD)score was recently developed with the intent to operationally define nonalcoholic fatty liver disease(NAFLD).However,there remained an external validation that confirmed its diagnostic performance,especially in patients with alcohol consumption or hepatitis virus ***:Diagnostic accuracy of the K-NAFLD score was evaluated in a hospital-based cohort consisting of 1388 participants who received Fibroscan®.Multivariate-adjusted logistic regression models and the contrast estimation of receiver operating characteristic curves were used for validation of the K-NAFLD score,fatty liver index(FLI),and hepatic steatosis index(HSI).Results:K-NAFLD-moderate[adjusted odds ratio(aOR)=2.53,95%confidence interval(CI):1.13-5.65]and K-NAFLD-high(aOR=4.14,95%CI:1.69-10.13)groups showed higher risks of fatty liver compared to the K-NAFLD-low group after adjustments for demographic and clinical characteristics,and FLI-moderate and FLI-high groups revealed aORs of 2.05(95%CI:1.22-3.43)and 1.51(95%CI:0.78-2.90),*** addition,the HSI was less predictive for Fibroscan®-defined fatty *** K-NAFLD and FLI also demonstrated high accuracy in the prediction of fatty liver in patients with alcohol consumption and chronic hepatitis virus infection,and the adjusted area under curve values were comparable between K-NAFLD and ***:Externally validation of the K-NAFLD and FLI showed that these scores may be a useful,noninvasive,and non-imaging modality for the identification of fatty *** addition,these scores also predicted fatty liver in patients with alcohol consumption and chronic hepatitis virus infection.

关键词： Nonalcoholic fatty liver disease Fatty liver index Hepatic steatosis index

Effects of mesenchymal stem cell on dopaminergic neurons,motor and memory functions in animal models of parkinson's disease:a systematic review and meta-analysis

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Neural Regeneration Research 2024年第7期19卷 1584-1592页

作者： Jong Mi park Masoud Rahmati sang Chul Lee Jae Il Shin Yong Wook Kim Department and Research Institute of Rehabilitation Medicine Yonsei University College of MedicineSeoulSouth Korea Department of Physical Education and Sport Sciences Faculty of Literature and Human SciencesLorestan UniversityKhoramabadIran Department of Pediatrics Yonsei University College of MedicineSeoulSouth Korea

parkinson’s disease is chara cterized by the loss of dopaminergic neurons in the substantia nigra pars com pacta,and although restoring striatal dopamine levels may improve symptoms,no treatment can cure or reve rse the disease *** cell therapy has a regenerative effect and is being actively studied as a candidate for the treatment of parkinson’s *** stem cells are considered a promising option due to fewer ethical concerns,a lower risk of immune rejection,and a lower risk of *** performed a meta-analysis to evaluate the therapeutic effects of mesenchymal stem cells and their derivatives on motor function,memory,and preservation of dopamine rgic neurons in a parkinson’s disease animal *** searched bibliographic databases(PubMed/MEDLINE,Embase,CENTRAL,Scopus,and Web of Science)to identify articles and included only pee r-reviewed in vivo interve ntional animal studies published in any language through J une 28,*** study utilized the random-effect model to estimate the 95%confidence intervals(CI)of the standard mean differences(SMD)between the treatment and control *** use the systematic review center for laboratory animal expe rimentation’s risk of bias tool and the collaborative approach to meta-analysis and review of animal studies checklist for study quality assessment.A total of 33studies with data from 840 parkinson’s disease model animals were included in the *** with mesenchymal stem cells significantly improved motor function as assessed by the amphetamine-induced rotational *** the stem cell types,the bone marrow MSCs with neurotrophic factor group showed la rgest effect size(SMD[95%CI]=-6.21[-9.50 to-2.93],P=0.0001,I^(2)=0.0%).The stem cell treatment group had significantly more tyrosine hydroxylase positive dopamine rgic neurons in the striatum([95%CI]=1.04[0.59 to 1.49],P=0.0001,I^(2)=65.1%)and substantia nigra(SMD[95%CI]=1.38[0.89 to 1.87],P=0.0001,I^(2)=75.3%),indicating a

关键词： animal animal experimentation mesenchymal stem cells models parkinson’s disease stem cell transplantation