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Numerical Visualization of Air Intake Induced by Free Surface Vortex

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Journal of Thermal Science 2017年第6期26卷 540-544页

作者： Young Kyu Park Mohan Kumar Dey Yoon Hwan Choi yeon won lee Research Institute of Industrial Science & Technology Pukyong National University Busan Korea Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering Pukyong National University Busan Korea Department of Mechanical Design Engineering Pukyong National University Busan Korea

Free surface vortex control is vital in a pump sump system because the air absorbed by free surface vortex induc- es noise, vibration, and cavitation corrosion on the pumping system. In this study, the change of free surface vor- tex and air absorption in a pump intake has been investigated by the Volume of Fraction （VOF） method with steady multiphase flow model in order to represent the behavior of the free surface vortex exactly. The homoge- neous free surface model is used to apply interactions of air and water. The results show that air intake by the free surface vortex motion can be visualized using the iso-surface of air volume fraction. The vortices make an air column from the free surface to the pump intake. Also, it was found that the flee surface vortex can be controlled by installing curtain walls.

关键词： free surface vortex numerical visualization curtain wall air intake

Effect of Nozzle Geometry on the Flow Characteristics of Spiral Flow Generated through an Annular Slit

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Journal of Thermal Science 2007年第2期16卷 149-154页

作者： Shigeru MATSUO Tae-Hun KIM Toshiaki SETOGUCHI Heuy Dong KIM yeon-won lee Department of Mechanical Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan Graduate school of Science and Technology Saga University1Honjo-machiSaga shiSaga 840-8502Japan School of Mechanical Engineering Andong National University388Songchun-dongAndong 760749Korea School of Mechanical Engineering College of EngineeringPukyong National UniversitySan 100Young-Dang DongBusanKorea

In comparison with previous researches of swirling flow, spiral flow generated in the spiral nozzle has some different flow characteristics. It does not need a forced tangential momentum to generate its velocity and has some different merits from the swirling flow such as long potential core and low tangential velocity. In this study, the effect of nozzle geometry on the flow characteristics in spiral nozzle was investigated by experiment and computation. As a result, the flow characteristics obtained by experiment has a satisfactory agreement with computational results, quantitatively and qualitatively.

关键词： nozzle flow characteristics momentum numerical simulation

Temperature Distribution and Thermal Stresses in Various Conditions of Moving Heating Source during Line Heating Process

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Journal of Thermal Science 2012年第1期21卷 82-87页

作者： Yoon Hwan Choi yeon won lee Kwang Choi Deog Hee Doh Kyoung Joon Kim Department of Mechanical and Automotive Engineering Pukyong National University Steel Structure Research Division Research Institute of Industrial Science & Technology Division of Mechanical and information Engineering Korea Maritime University

Line heating method is widely used to manufacture curved surfaces in ship building. The main factors governing the quality of the manufactured products are the moving velocity of the heating source, heating strength, and heating ways. In this study, the temperature distributions of the heated plate were investigated with the condition that the line heating process was automatic. The temperature variations were also investigated with the changes of those three variables. The numerical results showed that the peak temperature decreased as the moving velocity of the heating source increased. It also revealed that the peak temperatures changed linearly with the changes of the heating source.

关键词： Moving heat source Line heating Thermal stress Residual deformation Conductive heat transfer

Performance Analyses for a Cyclone Type Filter

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Journal of Thermal Science 2015年第3期24卷 290-294页

作者： Hyoung-June Kim Masahiro Takei Hyun Jin lee yeon won lee Yoon Hwan Choi Deog-Hee Doh School of Mechanical Engineering Artificial Science Division Chiba University Division of Mech. and Energy Systems Eng. Korea Maritime University Dept. of Mechanical and Automotive Engineering Pukyong National University

Flow characteristics inside a cyclone filter were investigated by the use of computational fluid dynamics(CFD). For computations, SST model was adopted. Parametric study was carried out considering the filtering performance. Revolution speeds were changed from 100 to 550 with 50 increments. A skirt is the driving source for cyclone operation. The influence of several design factors, such as the skirt length, the skirt gap and the return length to filtering performance was investigated under the particle diameter 100μm of debris material(Al, s.g.=2.7). The filtering performance was also investigated with the skirt length 28 mm changing the debris diameters from 1μm to 50μm. The flow rate of the working fluid was maintained at 0.55kg/s. It has been verified that the most influential factors to the filtering efficiencies was the skirt gap between the cyclone generator and the cyclone vessel.

关键词： CFD cyclone filter design factors filtering performances

Low temperature-mediated repression and far-red light-mediated induction determine morning FLOWERING LOCUS T expression levels

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Journal of Integrative Plant Biology 2024年第1期66卷 103-120页

作者： Hayeon Kim Hye won Kang Dae yeon Hwang Nayoung lee Akane Kubota Takato Imaizumi Young Hun Song Department of Agricultural Biotechnology Seoul National UniversitySeoul 08826Korea Department of Biology Ajou UniversitySuwon 16499Korea Plant Genomics and Breeding Institute Seoul National UniversitySeoul 08826Korea Graduate School of Science and Technology Nara Institute of Science and TechnologyIkomaNara 630‐0192Japan Department of Biology University of WashingtonSeattleWA 98195USA Institute of Agricultural Life Sciences Seoul National UniversitySeoul 08826Korea

In order to flower in the appropriate season,plants monitor light and temperature changes and alter downstream pathways that regulate florigen genes such as Arabidopsis(Arabidopsis thaliana)FLOWERING LOCUS T(FT).In Arabidopsis,FT messenger RNA levels peak in the morning and evening under natural long-day conditions(LDs).However,the regulatory mechanisms governing morning FT induction remain poorly *** morning FT peak is absent in typical laboratory LDs characterized by high red:far-red light(R:FR)ratios and constant ***,we demonstrate that ZEITLUPE(ZTL)interacts with the FT repressors TARGET OF EATs(TOEs),thereby repressing morning FT expression in natural *** LDs with simulated sunlight(R:FR=1.0)and daily temperature cycles,which are natural LD-mimicking environmental conditions,FT transcript levels in the ztl mutant were high specifically in the morning,a pattern that was mirrored in the toe1 toe2 double *** night-to-morning temperatures increased the inhibitory effect of ZTL on morning FT expression by increasing ZTL protein levels early in the ***-red light counteracted ZTL activity by decreasing its abundance(possibly via phytochrome A(phyA))while increasing GIGANTEA(GI)levels and negatively affecting the formation of the ZTL-GI complex in the ***,the phyA-mediated high-irradiance response and GI play pivotal roles in morning FT *** findings suggest that the delicate balance between low temperature-mediated ZTL activity and the far-red light-mediated functions of phyA and GI offers plants flexibility in fine-tuning their flowering time by controlling FT expression in the morning.

关键词： far-red light FLOWERING LOCUS T flowering time GIGANTEA low night-to-morning temperature natural long days phytochrome A red to far-red ratio ZEITLUPE

Heat Transfer Enhancement of Cu-H<sub>2</sub>O Nanofluid with Internal Heat Generation Using LBM

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Open Journal of Fluid Dynamics 2013年第2期3卷 92-99页

作者： Mohammad Abu Taher yeon won lee Heuy Dong Kim School of Mechanical Engineering Andong National University Andong South Korea School of Mechanical Engineering Pukyong National University Busan South Korea

Fluid flow and heat transfer analysis of Cu-H2O nanofluid in a square cavity using a Thermal Lattice Boltzmann Method (TLBM) have been studied in the present work. The LBM has built up on the D2Q9 model and the single relaxation time method called the Lattice-BGK (Bhatnagar-Gross-Krook) model. The effect of suspended nanoparticles on the fluid flow and heat transfer analysis have been investigated for different non dimensional parameters such as particle volume fraction (φ) and particle diameters (dp) in presence of internal heat generation (q) of nanoparticles. It is seen that flow behaviors and the average rate of heat transfer in terms of the Nusselt number (Nu) as well as the thermal conductivity of nanofluid are effectively changed with the different controlling parameters such as particle volume fraction (2% ≤ φ ≤ 10%), particle diameter (dp = 5 nm to 40 nm) with fixed Rayleigh number, Ra = 105. The present results of the analysis are compared with the previous experimental and numerical results for both pure and nanofluid and it is seen that the agreement is good indeed among the results.

关键词： Nanofluid Lattice-Boltzmann Volume Fractions Particle Diameter Heat Generation

Self-supported VO_(2)on polydopamine-derived pyroprotein-based fibers for ultrastable and flexible aqueous zinc-ion batteries

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Carbon Energy 2024年第7期6卷 1-13页

作者： Jeong Seok yeon Sul Ki Park Shinik Kim Santosh VMohite won Il Kim Gun Jang Hyun-Seok Jang Jiyoung Bae Sang Moon lee won GHong Byung Hoon Kim yeonho Kim Ho Seok Park School of Chemical Engineering College of EngineeringSungkyunkwan UniversityGyeonggi-doRepublic of Korea Department of Engineering University of CambridgeCambridgeUK Department of Applied Chemistry Konkuk UniversityChungjuRepublic of Korea Department of Chemistry Ulsan National Institute of Science and Technology(UNIST)College of Natural SciencesUlsanRepublic of Korea Department of Physics Incheon National UniversityIncheonRepublic of Korea Intelligent Sensor Convergence Research Center Incheon National UniversityIncheonRepublic of Korea Institute of Basic Science Incheon National UniversityIncheonRepublic of Korea Division of Material Analysis and Research Korea Basic Science InstituteDaejeonRepublic of Korea

A conventional electrode composite for rechargeable zinc-ion batteries(ZIBs)includes a binder for strong adhesion between the electrode material and the current ***,the introduction of a binder leads to electrochemical inactivity and low electrical conductivity,resulting in the decay of the capacity and a low rate *** present a binder-and conducting agent-free VO_(2)composite electrode using in situ polymerization of dopamine on a flexible current collector of pyroprotein-based *** as-fabricated composite electrode was used as a substrate for the direct growth of VO_(2)as a self-supported form on polydopamine-derived pyroprotein-based fibers(pp-fibers@VO_(2)(B)).It has a high conductivity and flexible nature as a current collector and moderate binding without conventional binders and conducting agents for the VO_(2)(B)*** addition,their electrochemical mechanism was *** energy storage is induced by Zn^(2+)/H^(+)coinsertion during discharging,which can be confirmed by the lattice expansion,the formation of by-products including Zn_(x)(OTf)_(y)(OH)_(2x−y)·nH_(2)O,and the reduction of V^(4+)to V^(3+).Furthermore,the assembled Zn//pp-fibers@VO_(2)(B)pouch cells have excellent flexibility and stable electrochemical performance under various bending states,showing application possibilities for portable and wearable power sources.

关键词： aqueous battery binder free conducting agent‐free flexible electrode zinc‐ion battery

Intelligent structured nanocomposite adhesive for bioelectronics and soft robots

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Nano Research 2024年第2期17卷 534-549页

作者： yeon Soo lee Min-Seok Kim Da Wan Kim Changhyun Pang School of Chemical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Mechanical Metrology Group Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Electronic Engineering Korea National University of TransportationChungbuk 27469Republic of Korea Samsung Advanced Institute for Health Sciences and Technology Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea

The remarkable functionality of biological systems in detecting and adapting to various environmental conditions has inspired the design of the latest electronics and robots with advanced *** review focuses on intelligent bio-inspired strategies for developing soft bioelectronics and robotics that can accommodate nanocomposite adhesives and integrate them into biological *** underlying principles of the material and structural design of nanocomposite adhesives were investigated for practical applications with excellent functionalities,such as soft skin-attachable health care sensors,highly stretchable adhesive electrodes,switchable adhesion,and untethered soft *** addition,we have discussed recent progress in the development of effective fabrication methods for micro/nanostructures for integration into devices,presenting the current challenges and prospects.

关键词： biomimetics bio-adhesive switchable adhesion bioelectronics nanocomposite soft robotics

Suboptimal Feature Selection Techniques for Effective Malicious Traffic Detection on Lightweight Devices

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1669-1687页

作者： So-Eun Jeon Ye-Sol Oh yeon-Ji lee Il-Gu lee Department of Future Convergence Technology Engineering Sungshin Women’s UniversitySeoul02844Korea Department of Convergence Security Engineering SungshinWomen’s UniversitySeoul02844Korea

With the advancement of wireless network technology,vast amounts of traffic have been generated,and malicious traffic attacks that threaten the network environment are becoming increasingly *** signature-based detection methods,static analysis,and dynamic analysis techniques have been previously explored for malicious traffic detection,they have limitations in identifying diversified malware traffic *** research has been focused on the application of machine learning to detect these ***,applying machine learning to lightweight devices like IoT devices is challenging because of the high computational demands and complexity involved in the learning *** this study,we examined methods for effectively utilizing machine learning-based malicious traffic detection approaches for lightweight *** introduced the suboptimal feature selection model(SFSM),a feature selection technique designed to reduce complexity while maintaining the effectiveness of malicious traffic *** performance was evaluated on various malicious traffic,benign,exploits,and generic,using the UNSW-NB15 dataset and SFSM sub-optimized hyperparameters for feature selection and narrowed the search scope to encompass all *** improved learning performance while minimizing complexity by considering feature selection and exhaustive search as two steps,a problem not considered in conventional *** experimental results showed that the detection accuracy was improved by approximately 20%compared to the random model,and the reduction in accuracy compared to the greedy model,which performs an exhaustive search on all features,was kept within 6%.Additionally,latency and complexity were reduced by approximately 96%and 99.78%,respectively,compared to the greedy *** study demonstrates that malicious traffic can be effectively detected even in lightweight device *** verified the possibility of detecting various attack

关键词： Feature selection lightweight device machine learning Internet of Things malicious traffic