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Transactions of Nonferrous Metals Society of China 2024年

作者： Yeongjung Kim Yong-Sung Eom Kwang-Seong Choi jong-hyun lee Department of Materials Science and Engineering， Seoul National University of Science and Technology， 232 Gongneung-ro Low-Carbon Integration Tech， Creative Research Section， ETRI， 218 Gajeong-ro Materials Research Institute for Future Convergence， Seoul National University of Science and Technology， 232 Gongneung-ro

Four types of submicron Ag-coated Cu particles with different Ag contents were prepared as sintering paste fillers， and the Ag contents of the particles were measured to be 10， 20， 30， and 40 wt%. Four types of particles （in order of increasing Ag content: A10， A20， A30， and A40） were surface-modified with stearic acid， to suppress the Ag shell dewetting and improve sinterability. The surface-modified particles were mixed with a polyol-based solvent to fabricate a resin-free paste. Subsequently， the pastes were screen-printed onto a slide glass and sintered at 250 ℃ in a nitrogen atmosphere for 1–10 min to form an electrode. The electrical resistivity of the sintered film as a function of sintering time was measured using a four-point probe. All the four surface-modified Cu@Ag particles with different Ag contents exhibited decreased electrical resistivity. Particularly， the largest difference in values after and before the surface modification was observed for A40 with the highest Ag content; the electrical resistivities of the initial and surface-modified particles were 1.51×10-4and 6.67×10-5Ω·cm， respectively， after sintering for 10 min. The findings of this study confirmed that the surface modification using stearic acid effectively suppressed the dewetting of the Ag shell and improved the sinterability of the submicron Cu@Ag particles.

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Die sinter bonding in air using copper formate preform for formation of full-density bondline

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Transactions of Nonferrous Metals Society of China 2021年第6期31卷 1717-1728页

作者： Yun-Ju lee jong-hyun lee Department of Materials Science and Engineering Seoul National University of Science and Technology232 Gongneung-roNowon-guSeoul 139-743Korea

Pressure-assisted sinter bonding was performed in air at 250−350℃ using a preform comprising copper formate particles to form a bondline that is sustainable at high temperatures.H2 and CO generated concurrently by the pyrolysis of copper formate at 210℃ during the sinter bonding removed the native oxide and other oxides grown on bulk Cu finishes,enabling interface ***,Cu produced in situ by the reduction of Cu(II)accelerated the sinter ***,the bonding achieved at 300−350℃ under 5 MPa exhibited sufficient shear strength of 20.0−31.5 MPa after 180−300 min of sinter *** addition,an increase in pressure to 10 MPa resulted in shear strength of 21.9 MPa after an extremely short time of 30 s at 250℃,and a near-full-density bondline was achieved after 300 *** obtained results indicate the promising potential of the preform comprising copper formate particles for high-speed sinter bonding.

关键词： structural materials microstructure mechanical properties copper formate preform sinter bonding pyrolysis

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

Reliability of flip-chip bonded RFID die using anisotropic conductive paste hybrid material

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 175-181页

作者： Jun-Sik lee Jun-Ki KIM Mok-Soon KIM Namhyun KANG jong-hyun lee Advanced Joining Technology Team/Microjoining Center Korea Institute of Industrial Technology(KITECH) Yeonsu-gu Incheon 406-840 Korea School of Materials Science & Engineering Inha University Department of Materials Science & Engineering Pusan National University Department of Materials Science & Engineering Seoul National University of Technology

A reliability of flip-chip bonded die as a function of anisotropic conductive paste (ACP) hybrid materials, bonding conditions, and antenna pattern materials was investigated during the assembly of radio frequency identification(RFID) inlay. The optimization condition for flip-chip bonding was determined from the behavior of bonding strength. Under the optimized condition, the shear strength for the antenna printed with paste-type Ag ink was larger than that for Cu antenna. Furthermore, an identification distance was varied from the antenna materials. Comparing with the Ag antenna pattern, the as-bonded die on Cu antenna showed a larger distance of identification. However, the long-term reliability of inlay using the Cu antenna was decreased significantly as a function of aging time at room temperature because of the bended shape of Cu antenna formed during the flip-chip bonding process.

关键词： RFID inlay ACP flip-chip, bonding process reliability

Rapid pressure-assisted sinter bonding in air using 200 nm Cu particles and enhancement of bonding strength by successive pressureless annealing

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Transactions of Nonferrous Metals Society of China 2022年第2期32卷 629-638页

作者： Myeong In KIM jong-hyun lee Department of Materials Science and Engineering Seoul National University of Science and Technology232 Gongneung-roNowon-guSeoul 139-743Korea

To design an effective and realistically applicable sinter bonding process for power devices,we proposed a two-step process using a 200 nm Cu-particle-based paste to form a bondline having high-temperature sustainability and superior thermal *** process involved rapid pressure-assisted sinter bonding in air followed by pressureless annealing in a nitrogen *** the case of a paste prepared with a mixture of 20 wt.%malic acid and 80 wt.%ethylene glycol,sinter bonding at 300℃and 5 MPa for only 30 s resulted in a sufficient shear strength of 23.1 *** shear strength was significantly enhanced to 69.6 MPa by the additional pressureless aging for 30 ***,the two-step sinter bonding process is expected to provide an outstanding production rate as a next-generation sinter bonding process.

关键词： submicron Cu particles Cu paste malic acid sinter bonding successive annealing shear strength

Mechanical characteristics of tensile strength ratio method compared to other parameters used for moisture susceptibility evaluation of asphalt mixtures

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第6期6卷 621-630页

作者： Thanh Chung Do Van Phuc Tran Van Phuc Le hyun jong lee Won Jae Kim Department of Civil and Environmental Engineering Sejong UniversitySeoul 143-747South Korea Faculty of Civil Engineering University of Transport and CommunicationsHo Chi Minh CityVietnam

In this study,mechanical characteristics of tensile strength ratio(TSR)were evaluated by comparing it to other methods in evaluating moisture sensitivity of asphalt *** types of asphalt mixtures with and without anti-stripping additives were prepared and tested in the *** compressive strength(UCS)and indirect tensile(IDT)testing were conducted to determine the mixture’s tensile strength ratio and cohesion ratio(CR).Determining TSR alone was found to be insufficient when evaluating moisture *** is a need to consider both TSR and wet IDT strength to properly evaluate moisture behavior of asphalt ***,it was found that the cohesion and the IDT strength have a good relation in which the minimum condition of the slope,must be ***,it was observed thatβvalues change depending on material type and ***,there is a need to evaluate theseβvalues for varying material and testing *** addition,it was found that the TSR and CR results are highly correlated with an average difference of 1.5%.Furthermore,other tests such as Marshall stability and dynamic immersion were also *** was found that Marshall stability ratio(MSR)and Marshall stability to flow ratio(MSFR)values are less sensitive to moisture effect when measuring moisture resistance compared to TSR ***,the 48 h testing result of the dynamic immersion test showed better correlation with TSR values.

关键词： Asphalt mixtures Moisture damage Anti-stripping additives Tensile strength ratio Cohesion strength ratio

Small but big leaps towards neuroglycomics:exploring N-glycome in the brain to advance the understanding of brain development and function

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Neural Regeneration Research 2024年第3期19卷 489-490页

作者： Boyoung lee hyun Joo An Center for Cognition and Sociality Institute for Basic Science(IBS)DaejeonSouth Korea Asia-Pacific Glycomics Reference Site DaejeonSouth Korea Graduate School of Analytical Science&Technology Chungnam National UniversityDaejeonSouth Korea

Glycosylation is a process that involves the addition of sugar moieties or glycans to different types of molecules,including proteins,lipids,and nucleic *** these,protein glycosylation is one of the most prevalent forms of post-translational modification,playing a crucial role in biological *** more than ten monosaccharides identified within mammalian brain cells and more than 1×1012 possible combinations,the heterogeneity of glycosylation is extensive(Conroy et al.,2021).The diversity of glycans and the complexity of their structures allow for a wide range of protein functions.N-glycans are one of the most abundant forms of glycans and are involved in various cellular functions.N-glycans can be added to proteins at specific sequons,Asn-X-Ser/Thr,and are classified into three main types in mature glycoproteins:high mannose,complex,and *** mannose N-glycans consist of 5-9 mannose residues linked to a chitobiose core and undergo processing into complex or hybrid forms in the Golgi apparatus(Varki et al.,2017).Complex N-glycans are more diverse and contain various branched structures such as antennae with fucose,galactose,and sialic acid *** N-glycans contain one or more complex branches in conjunction with an oligomannose branch(Fisher and Ungar,2016).Understanding the specific functions of these different types of N-glycans in protein regulation,folding,and function is an active area of research in the life sciences,including glycobiology.

关键词： functions function apparatus

Novel Rifle Number Recognition Based on Improved YOLO in Military Environment

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Computers, Materials & Continua 2024年第1期78卷 249-263页

作者： hyun Kwon Sanghyun lee Department of Artificial Intelligence and Data Science Korea Military AcademySeoulKorea Graduate School of Information Security Korea Advanced Institute of Science and TechnologyDaejeonKorea

Deep neural networks perform well in image recognition,object recognition,pattern analysis,and speech *** military applications,deep neural networks can detect equipment and recognize *** military equipment,it is necessary to detect and recognize rifle management,which is an important piece of equipment,using deep neural *** have been no previous studies on the detection of real rifle numbers using real rifle image *** this study,we propose a method for detecting and recognizing rifle numbers when rifle image data are *** proposed method was designed to improve the recognition rate of a specific dataset using data fusion and transfer *** the proposed method,real rifle images and existing digit images are fusedas trainingdata,andthe final layer is transferredto theYolov5 *** detectionand recognition performance of rifle numbers was improved and analyzed using rifle image and numerical *** used actual rifle image data(K-2 rifle)and numeric image datasets,as an experimental *** was used as the machine learning *** results show that the proposed method maintains 84.42% accuracy,73.54% precision,81.81% recall,and 77.46% F1-score in detecting and recognizing rifle *** proposed method is effective in detecting rifle numbers.

关键词： Machine learning deep neural network rifle number recognition detection

Realizing High Thermoelectric Performance in n-Type Se-Free Bi2Te3 Materials by Spontaneous Incorporation of FeTe2 Nanoinclusions

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Energy & Environmental Materials 2024年第4期7卷 344-354页

作者： Jamil Ur Rahman Woo hyun Nam Yong-Jae Jung jong Ho Won jong-Min Oh Nguyen Van Du Gul Rahman Víctor M.García-Suárez Ran He Kornelius Nielsch Jung Young Cho Won-Seon Seo jong Wook Roh Sang-il Kim Soonil lee Kyu Hyoung lee hyun Sik Kim Weon Ho Shin Leibniz Institute for Solid State and Materials Research Advanced Materials Convergence R&D Division Korea Institute of Ceramic Engineering & Technology Department of Electronic Materials Engineering Kwangwoon University Department of Energy Engineering Dankook University Faculty of Fundamental Science Phenikaa University Department of Physics Quaid-i-Azam University Departamento de Física Universidad de Oviedo Nanomaterials and Nanotechnology Research Center-CINN Department of Materials Science and Engineering Yonsei University School of Nano & Materials Science and Engineering Kyungpook National University Department of Materials Science and Engineering University of Seoul School of Materials Science and Engineering Changwon National University

Bi2Te3-based materials have drawn much attention from the thermoelectric community due to their excellent thermoelectric performance near room ***,the stability of existing n-type Bi2（Te,Se）3materials is still low due to the evaporation energy of Se (37.70 kJ mol-1) being much lower than that of Te (52.55 kJ mol-1).The evaporated Se from the material causes problems in interconnects of the module while degrading the efficiency.

关键词： Bi2Te3 energy harvesting FeTe2 nanoinclusion n-type materials thermoelectric

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