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Journal of Environmental Sciences 2020年第6期32卷 11-17页

作者： Jung Joon lee Jihyeon Park Bo-hyun Kim Sunjong lee Department of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419South Korea Korea Institute of Industrial Technology 89 Yangdaegiro-gilIpjang-myeonCheonan-si 31056South Korea

Regeneration of pure water is an important issue not only for the healthy life but also for the fine control of precise processes in various *** important issue in ultrahigh purified water is to reduce the amount of total organic carbon(TOC).Herein,we introduce a new approach to reduce the TOC using the surface silanized nanoparticles,in which the magnetic nanoparticles(mNPs)are silanized and then complexed with ion exchange resin(IER)*** Fe3O4 mNPs are surface modified by using high concentrated vinyltrimethoxysilane(VTMS)and then adhered on the surface of IER *** surface modified mNPs have a thick-shell of polysiloxane layer varying from 5 to 22 nm depending on the amount of VTMS used,which leads the significant increase of specific surface *** IER beads embedding VTMS-silanized mNPs achieves about 7μg/L of the TOC level in ultrapure water system,which is two orders less than 228μg/L of the feeding water and one order less than 96μg/L from the system using pristine IER *** result is mainly attributed to the polysiloxane layer forming broccoli-like surface structure and some part by the vinyl group of VTMS exposed to the amines in the water.

关键词： Total organic carbon Ultrapure water Magnetic nanoparticle Ion-exchange resin Hybrid structure

Current Progress on the Geological Record of Microbialites and Microbial Carbonates

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Acta Geologica Sinica(English Edition) 2014年第1期88卷 260-275页

作者： CHEN Jitao lee Jeong-hyun Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences School of Earth and Environmental Sciences Seoul National University

This paper reviews the current progress and problems in the study of microbialites and microbial carbonates. Microbialites and microbial carbonates, formed during growth of microbes by their calcification and binding of detrital sediment, have recently become one of the most popular geological topics. They occur throughout the entire geological history, and bear important theoretical and economic significances due to their complex structures and formative processes. Microbialites are in place benthic microbial buildups, whereas microbial carbonates can be classified into two categories： stabilized microbial carbonates（i.e., carbonate microbialites, such as stromatolites and thrombolites） and mobilized microbial carbonates（i.e., microbial carbonate grains, such as oncoids and microbial lumps）. Various texture, structures, and morphologies of microbialites and microbial carbonates hamper the systematic description and classification. Moreover, complex calcification pathways and diagenetic modifications further obscure the origin of some microbialites and microbial carbonates. Recent findings of abundant sponge spicules in previously identified ＂microbialites＂ challenge the traditional views about the origins of these ＂microbialites＂ and their implications to reef evolution. Microbialites and microbial carbonates did not always flourish in the aftermath of extinction events, which, together with other evidences, suggests that they are affected not only by metazoans but also by other geological factors. Their growth, development, and demise are also closely related to sea-level changes, due to their dependence on water depth, clarity, nutrient, and sunlight. Detailed studies on microbialites and microbial carbonates throughout geological history would certainly help understand causes and effects of major geological events as well as the coevolution of life and environment.

关键词： microbialite microbial carbonate reef calcification calcimicrobe

Etching characteristics of thin SiON films using a liquefied perfluorocarbon precursor of C_6F_(12)O with a low global warming potential

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Plasma Science and Technology 2020年第10期22卷 135-144页

作者： Junmyung lee Yunho NAM Jongchan lee hyun Woo lee Kwang-Ho KWON Department of Control and Instrumentation Engineering Korea UniversitySejong 30019Republic of Korea Department of Aeronautic Computer Engineering Hanseo UniversitySeosan 31962Republic of Korea

Perfluorocarbon gas is widely used in the semiconductor ***,perfluorocarbon has a negative effect on the global environment owing to its high global warming potential(GWP) *** alternative solution is ***,we evaluated the possibility of replacing conventional perfluorocarbon etching gases such as CHF_3 with C_6F_(12)O,which has a low GWP and is in a liquid state at room *** this study,silicon oxynitride(SiON) films were plasma-etched using inductively coupled CF4+C_6F_(12)O+O_2 mixed ***,the etching characteristics of the film,such as etching rate,etching profile,selectivity over Si,and photoresist,were investigated.A double Langmuir probe was used and optical emission spectroscopy was performed for plasma *** addition,a contact angle goniometer and x-ray photoelectron spectroscope were used to confirm the change in the surface properties of the etched SiON film ***,the etching characteristics of the C_6F_(12)O mixed plasma exhibited a lower etching rate,higher SiON/Si selectivity,lower plasma damage,and more vertical etched profiles than the conventional CHF_3 mixed *** addition,the C_6F_(12)O gas can be recovered in the liquid state,thereby decreasing global *** results confirmed that the C_6F_(12)O precursor can sufficiently replace the conventional etching gas.

关键词： global warming potential perfluorocarbon silicon oxynitride etching characteristics liquid-state perfluorocarbon

Microstructure characteristics and effect of grain orientation on magnetic properties of Fe_(63)Co_(32)Gd_5 alloy ribbons

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Journal of Central South University 2015年第6期22卷 2014-2019页

作者：姚文静王楠 lee Je-hyun Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education School of Science Northwestern Polytechnical University Engineering Research Center for Integrated Mechatronics Materials and Components Changwon National University

By using the melt spinning techniques, the Fe63Co32Gd5 alloy ribbons with 15-50 m in thickness and 3-7 mm in width were prepared at the wheel speeds of 15, 20, 25 and 35 m/s. The rapid solidification microstructures were characterized by three layers, the middle layer of which reaches 80% thickness and forms the column grain of(Fe,Co) solid with Gd solution. Grain refinement takes place with the increase of the wheel speed. And after 0.5 h heat treatment at 823 K, the ribbon thickness becomes larger and the middle layer of column grain is very orderly perpendicular to the ribbon plane. The coercivity of quenched and annealed Fe63Co32Gd5 ribbons both have the inflection point at the wheel speed of 20 m/s, and the tendency is declining. The heat treatment processing makes the coercivity become lower by improving the order of(Fe,Co)17Gd2 compound. The saturation magnetization of quenched ribbons increases with the enhancement of wheel speed, whereas that of annealed ones decreases firstly and then increases. The minimum coercivity is 5.30×103 A/m and the maximum saturation magnetization is 163.62 A·m2/kg, which is obtained in the conditions of the wheel speed of 35 m/s and 0.5 h heat treatment at the temperature of 823 K.

关键词： Fe-Co-Gd alloy ribbon rapid solidification phase composition magnetic properties

The Sensing Behavior to Volatile Organic Compounds Gas on Polypyrrole Sensor under Humidity Condition

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稀有金属材料与工程 2006年第A3期35卷 65-66页

作者： Jae-hyun Cho Joon-Boo Yu Sung-Ok Sohn Duk-dong lee Jeung-Soo Huh Department of Material Science Metallurgy Kyungpook National UniversitySangyuk-Dong 1370DaeguKorea School of Electronic Engineering Kyungpook National UniversitySangyuk-Dong 1370DaeguKorea

Polypyrrole (PPy) powder was synthesized by chemical polymerization at 0℃under atmospheric condition and its layer was prepared by dip coating method on the alumina substrate with interdigitated *** influence of relative humidity (RH 0～70%) to PPy sensor was *** measuring temperature was fixed at 25℃.Methanol and benzene were used as target *** analytic techniques were examined to observe changes in the properties of PPy *** sensitivity of PPy sensor to water vapor was linearly increased with the increasing *** the relative humidity increase from 0% to 70%,the sensitivities to methanol and benzene vapor were reduced,and reduction ratio of sensitivity was 94%, 92.5% at RH 70%,respectively.

关键词： VOCs polypyrrole humidity effect gas sensor

The photodynamic therapy on Streptococcus mutans biofilms using erythrosine and dental halogen curing unit

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International Journal of Oral Science 2012年第4期4卷 196-201页

作者： Young-Ho lee Ho-Won Park Ju-hyun lee hyun-Woo Seo Si-Young lee Department of Pediatric Dentistry Graduate SchoolCollege of DentistryGangneung-Wonju National University Department of Pediatric Dentistry College of DentistryGangneung-Wonju National University Department of Microbiology and Immunology College of DentistryGangneung-Wonju National University

The purpose of our study was to evaluate the effect of photodynamic therapy （PDT）, using erythrosine as a photosensitizing agent and a dental halogen curing unit as a light source, on Streptococcus mutans in a biofilm phase. The S. mutans biofilms were formed in a 24-well cell culture cluster. Test groups consisted of biofilms divided into four groups： group 1： no photosensitizer or light irradiation treatment （control group）; group 2： photosensitizer treatment alone; group 3： light irradiation alone; group 4： photosensitizer treatment and light irradiation. After treatments, the numbers of colony-forming unit （CFU） were counted and samples were examined by confocal laser scanning fluorescence microscopy （CLSM）. Only group 4 （combined treatment） resulted in significant increases in cell death, with rates of 75% and 55% after 8 h of incubation, and 74% and 42% at 12 h, for biofilms formed in brain-heart infusion （BHI） broth supplemented with 0% or O. 1% sucrose, respectively. Therefore, PDT of S. mutans biofilms using a combination of erythrosine and a dental halogen curing unit, both widely used in dental clinics, resulted in a significant increase in cell death. The PDT effects are decreased in biofilms that form in the presence of sucrose.

关键词： biofilms dental halogen curing unit erythrosine photodynamic therapy Streptococcus mutans

Counter-balancing effects of Si on C partitioning and stacking fault energy of austenite in 10Mn quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第3期98卷 248-257页

作者： dong Hwi Kim Jee-hyun Kang Hojun Gwon Joo hyun Ryu Sung-Joon Kim Graduate Institute for Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Materials Science and Engineering Institute of Materials TechnologyYeungnam UniversityGyeongsan 38541Republic of Korea POSCO Technical Research Laboratories POSCOGwangyang 57807Republic of Korea

Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize *** 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free ***,the suppression of carbide formation promoted C partitioning into austenite as ***,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of *** partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility *** was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the *** resulting strengthening effect compensated for the softening caused by martensite ***,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.

关键词： Steels Q&P steel Silicon Austenite stability Tensile deformation Stacking fault energy Medium Mn steel

Evaluation of ring surfaces with several coatings for friction,wear and scuffing life

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中国有色金属学会会刊：英文版 2009年第4期19卷 992-996页

作者： Dae-hyun CHO Young-Ze lee School of Mechanical Engineering Sungkyunkwan University

Friction and wear of the sliding components in an automobile cause an increase in both fuel consumption and *** engine components involved with sliding contact are all susceptible to scuffing failure at some points during their operating ***,it is important to evaluate the effects of various surface coatings on the tribological characteristics of the piston ring and cylinder block surface of a diesel *** and scuffing tests were conducted using a friction and wear measurement of the piston ring and cylinder block in a low friction diesel *** frictional forces,wear amounts and cycles to scuffing in the boundary lubricated sliding condition were measured using the reciprocating wear *** tester used a piece of the cylinder block as the reciprocating specimen and a segment of the piston ring material as the fixed *** coatings on the ring specimen were used,such as DLC,TiN,Cr-ceramic and TiAlN,in order to improve the tribological characteristics of the *** coefficients of friction were monitored during the tests,and the wear volumes of the piston ring surfaces with various coatings were *** results show that the DLC coating exhibits better tribological properties than the other *** graphite structure of this coating is responsible for the low friction and wear of the DLC *** TiN and DLC coatings show better scuffing resistance than the other *** TiN and Cr-ceramic coated rings show good wear resistance and high friction.

关键词：涂层表面摩擦评价生活划伤磨损

Synthesis of tin nanoparticles through modified polyol process and effects of centrifuging and drying on nanoparticles

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中国有色金属学会会刊：英文版 2012年第S3期22卷 707-711页

作者： Sang-Soo CHEE Jong-hyun lee Department of Materials Science and Engineering Seoul National University of Science and Technology

Sn nanoparticles with average diameter of 13.1 nm were synthesized by modified polyol process,and their melting point was observed to be about 40 °C less than that of bulk *** though Sn nanoparticles are solid and covered with thin PVP capping and oxide layer,Sn nanoparticles in solution agglomerate upon centrifugation,resulting in a melting point *** to stickiness of the PVP capping layer,extensive aggregation between Sn nanoparticles was observed after ***,the aggregation behavior did not further influence the melting point,because actual agglomeration did not occur in the aggregates.

关键词： tin nanoparticle melting point centrifugation agglomeration aggregation

Enhancing Identity Protection in Metaverse-Based Psychological Counseling System

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Computers, Materials & Continua 2024年第1期78卷 617-632页

作者： Jun lee Hanna lee Seong Chan lee hyun Kwon Department of Game Software Hoseo UniversityAsan-si31499Korea Yatav Enter Seoul04799Korea Department of Artificial Intelligence and Data Science Korea Military AcademySeoul01805Korea

Non-face-to-face psychological counseling systems rely on network technologies to anonymize information regard-ing client ***,these systems often face challenges concerning voice data leaks and the suboptimal communication of the client’s non-verbal expressions,such as facial cues,to the *** study proposes a metaverse-based psychological counseling system designed to enhance client identity protection while ensuring efficient information delivery to counselors during non-face-to-face *** proposed systemincorporates a voicemodulation function that instantlymodifies/masks the client’s voice to safeguard their ***,it employs real-time client facial expression recognition using an ensemble of decision trees to mirror the client’s non-verbal expressions through their avatar in the metaverse *** system is adaptable for use on personal computers and smartphones,offering users the flexibility to access metaverse-based psychological counseling across diverse *** performance evaluation of the proposed system confirmed that the voice modulation and real-time facial expression replication consistently achieve an average speed of 48.32 frames per second or higher,even when tested on the least powerful smartphone ***,a total of 550 actual psychological counseling sessions were conducted,and the average satisfaction rating reached 4.46 on a 5-point *** indicates that clients experienced improved identity protection compared to conventional non-face-to-face metaverse counseling ***,the counselor successfully addressed the challenge of conveying non-verbal cues from clients who typically struggled with non-face-to-face psychological *** proposed systemholds significant potential for applications in interactive discussions and educational activities in the metaverse.

关键词： Metaverse counseling system face tracking identity protection