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Virtual Mold Technique in Thermal Stress Analysis during Casting Process

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Journal of Materials Science & Technology 2008年第3期24卷 359-363页

作者： Si-Young Kwak Jae-wook Baek Jeong-ho Nam Jeong-kil Choi E-Design Center Korea Institute of Industrial Technology Department of Virtual Engineering Korea University of Science & Technology

It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.

关键词： Casting process Thermal stress analysis Virtual mold

On the global existence of weak solutions for the Cucker-Smale-Navier-Stokes system with shear thickening

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Science China Mathematics 2018年第11期61卷 2033-2052页

作者： Seung-Yeal ha hwa kil Kim Jae-Myoung Kim Jinyeong Park Department of Mathematical Sciences and Research Institute of Mathematics Seoul National University Seoul 08826 Republic of Korea Korea Institute for Advanced Study Seoul 02455 Republic of Korea Department of Mathematics Education Hannam University Daejeon 34430 Republic of Korea Department of Mathematical Sciences Seoul National University Seoul 08826 Republic of Korea Department of Mathematics and Research Institute of Natural Sciences Hanyang University Seoul 04763 Republic of Korea

we study the large-time dynamics of Cucker-Smale(C-S)flocking particles interacting with nonNewtonian incompressible *** of particles and fluids were modeled using the kinetic Cucker-Smale equation for particles and non-Newtonian Navier-Stokes system for fluids,respectively and these two systems are coupled via the drag force,which is the main flocking(alignment)mechanism between particles and *** present a global existence theory for weak solutions to the coupled Cucker-Smale-Navier-Stokes system with shear *** also use a Lyapunov functional approach to show that sufficiently regular solutions approach flocking states exponentially fast in time.

关键词： emergence flocking Cucker-Smale model Navier-Stokes equation non-Newtonian fluid

ENERGY ABSORPTION CONTROL ChARACTERISTICS OF AL ThIN-wALLED TUBES UNDER IMPACT LOAD

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Acta Mechanica Solida Sinica 2008年第4期21卷 383-388页

作者： kil-Stmg Lee Yong-Jun Yang Sun-Kyu Kim In-Young Yang Department of Mechanical Design Engineering Chostrn University 375 Seosuk-dong Dong-gu Gwangju 501-759 Korea Department of Advanced Parts and Materials Engineering Graduate School Chosun University 375 Seosuk-dong Dong-gu Gwangju 501-759 Korea Department of Automobile Engineering Iksan National College 194-5 Ma-dong Iksan Chonbuk 570-752 Korea

An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by impact loading to develop the optimum structural members. here, the controller is introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. when the controller were used, the experimental results of crushing of square tubes controlled by the controller＇s elements showed a good candidate for a controllable energy absorption capability in impact crushing.

关键词： impact load Al thin-walled tubes energy absorption controller

Increasing concentrations of dietary threonine,tryptophan,and glycine improve growth performance and intestinal health with decreasing stress responses in broiler chickens raised under multiple stress conditions

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Animal Nutrition 2024年第3期18卷 145-153页

作者： hyun woo Kim Jong hyuk Kim Gi Ppeum han Dong Yong kil Department of Animal Science and Technology Chung-Ang UniversityAnseong-siGyeonggi-do 17546Republic of Korea Department of Animal Science Chungbuk National UniversityCheongju 28644Republic of Korea

The current study aimed to compare the effects of increasing concentrations of dietary threonine(Thr),tryptophan(Trp),and glycine(Gly)on growth performance,stress biomarkers,and intestinal function in broiler chickens under multiple stress *** hundred sixty broiler chickens at 21 d old were randomly allotted to 5 treatments with 8 *** in a positive control(PC)treatment were raised under low stock density(16.9 birds/m^(2) per cage)with recommended environmental conditions,whereas birds in 4 treatments were subjected to multiple stress conditions:a cyclic heat stress of 30±0.3℃ for 10 h and 23±0.2℃ for 14 h per day with high stock density(25.3 birds/m^(2) per cage).A basal diet was assigned to both PC and negative control(NC)*** additional diets were individually formulated to contain double concentrations of digestible Thr,Trp,or Gly+Ser compared with their concentrations in the basal *** experiment lasted for 14 *** showed that NC treatment had less growth performance(Phelial electrical resistance(TEER;Pher corticosterone(CORT)concentrations than PC *** treatment showed the least(Phad less(P=0.026)feather CORT concentrations,but had greater(Phan NC *** conclusion,increasing concentrations of dietary Thr,Trp,or Gly improve the growth performance and intestinal health in broiler chickens with decreasing stress response under multiple stress conditions.

关键词： Broiler chicken Glycine Multiple stress Threonine Tryptophan

Impact analysis of casting parts considering shrinkage cavity defect

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China Foundry 2011年第1期8卷 112-116页

作者： Si-Young Kwak Jie Cheng Jeong-kil Choi Center for e-Design Korea Institute of lndustrial Technology Incheon 406-800 Korea Department of Virtual Engineering School of Engineering Korea University of Science ＆ Technology Daejeon Korea

Shrinkage cavity may be detrimental to mechanical performances of casting *** a consequence,design engineers often use overly large safety factors in many designs due to insufficient understanding of quantitative effects of shrinkage cavity *** this paper,process of Al alloy wheel impact test was computationally analyzed for both the wheel models with and without shrinkage cavity *** on shrinkage cavity data obtained from industrial CT (Computerized Tomography),the shrinkage cavity defects were modeled with SSM (Shape Simplification Method),which reconstructs shrinkage cavity defects to hollow spheroid *** the impact simulation was conducted,the results show that under impact test condition,the wheel considering shrinkage cavity defects may fracture while the sound-assumed wheel may not.

关键词： casting shrinkage cavity defect impact computational analysis Al alloy wheel

Novel Architecture of OneM2M-Based Convergence Platform for Mixed Reality and IoT

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Computers, Materials & Continua 2022年第4期71卷 51-69页

作者： Seungwoon Lee woogeun kil Byeong-hee Roh SJ Kim Jin-suk Kang Department of Computer Engineering and Department of AI Convergence Network Ajou UniversitySuwon16499Korea howard R.hughes College of Engineering University of NevadaLas VegasNV89154USA AST Co.Ltd. Suwon16681Korea

There have been numerous works proposed to merge augmented reality/mixed reality(AR/MR)and Internet of Things(IoT)in various ***,they have focused on their specific target applications and have limitations on interoperability or reusability when utilizing them to different domains or adding other devices to the *** paper proposes a novel architecture of a convergence platform for AR/MR and IoT systems and *** proposed architecture adopts the oneM2M IoT standard as the basic framework that converges AR/MR and IoT systems and enables the development of application services used in general-purpose environments without being subordinate to specific systems,domains,and device *** implement the proposed architecture utilizing the open-source oneM2M-based IoT server and device platforms released by the open alliance for IoT standards(OCEAN)and Microsoft holoLens as an MR device *** also suggest and demonstrate the practical use cases and discuss the advantages of the proposed architecture.

关键词： Internet of things(IoT) augmented realty(AR) mixed reality(MR) microsoft holoLens oneM2M convergence platform

Multi-Binary Classifiers Using Optimal Feature Selection for Memory-Saving Intrusion Detection Systems

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Computer Modeling in Engineering & Sciences 2024年第11期141卷 1473-1493页

作者： Ye-Seul kil Yu-Ran Jeon Sun-Jin Lee Il-Gu Lee Department of Future Convergence Technology Engineering Sungshin Women’s UniversitySeoul02844Republic of Korea Department of Convergence Security Engineering Sungshin Women’s UniversitySeoul02844Republic of Korea

with the rise of remote work and the digital industry,advanced cyberattacks have become more diverse and complex in terms of attack types and characteristics,rendering them difficult to detect with conventional intrusion detection ***-based intrusion detection methods can be used to detect attacks;however,they cannot detect new *** detection and response(EDR)tools are attracting attention as a means of detecting attacks on endpoints in real-time to overcome the limitations of signature-based intrusion detection ***,EDR tools are restricted by the continuous generation of unnecessary logs,resulting in poor detection performance and memory *** learning-based intrusion detection techniques for responding to advanced cyberattacks are memory intensive,using numerous features;they lack optimal feature selection for each attack *** overcome these limitations,this study proposes a memory-efficient intrusion detection approach incorporating multi-binary classifiers using optimal feature *** proposed model detects multiple types of malicious attacks using parallel binary classifiers with optimal features for each attack *** experimental results showed a 2.95%accuracy improvement and an 88.05%memory reduction using only six features compared to a model with 18 ***,compared to a conventional multi-classification model with simple feature selection based on permutation importance,the accuracy improved by 11.67%and the memory usage decreased by 44.87%.The proposed scheme demonstrates that effective intrusion detection is achievable with minimal features,making it suitable for memory-limited mobile and Internet of Things devices.

关键词： Endpoint detection and response feature selection machine learning malware detection

Interannual Variation of Tropical Night Frequency in Beijing and Associated Large-Scale Circulation Background

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Advances in Atmospheric Sciences 2012年第2期29卷 295-306页

作者： Jong-kil PARK 陆日宇李超凡 Eun Byul KIM Department of Atmospheric Environment Information Engineering Atmospheric Environment Information Research Center Inje University State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

This study examined the variability in frequency of tropical night occurrence （i.e., minimum air tem- perature 25℃） in Beijing, using a homogenized daily temperature dataset during the period 1960–2008. Our results show that tropical nights occur most frequently in late July and early August, which is consis- tent with relatively high air humidity associated with the rainy season in Beijing. In addition, year-to-year variation of tropical night occurrence indicates that the tropical nights have appeared much more frequently since 1994, which can be illustrated by the yearly days of tropical nights averaged over two periods： 9.2 days of tropical nights per year during 1994–2008 versus 3.15 days during 1960–1993. These features of tropical night variations suggest a distinction between tropical nights and extreme heat in Beijing. we further investigated the large-scale circulations associated with the year-to-year variation of tropical night occurrence in July and August, when tropical nights appear most frequently and occupy 95% of the annual sum. After comparing the results in the two reanalysis datasets （NCEP/NCAR and ERA-40） and considering the possible effects of decadal change in the frequency of tropical nights that occurred around 1993/94, we conclude that on the interannual time scale, the cyclonic anomaly with a barotropic structure centered over Beijing is responsible for less frequent tropical nights, and the anticyclonic anomaly is responsible for more frequent occurrence of tropical nights over Beijing.

关键词： tropical night large-scale circulation interannual variability decadal change Beijing

Dietary intake of bamboo vinegar and charcoal powder(BVC)enhances resistance of African catfi sh Clarias gariepinus to bacterial pathogen

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Journal of Oceanology and Limnology 2022年第1期40卷 336-346页

作者： Kwangjin JU Moyngsuk kil Sanghyok RI Tongchol KIM Lining ZhANG Maocang YAN Guangxu LIU College of Animal Sciences Zhejiang UniversityHangzhou 310058China College of Aquaculture Wonsan Fisheries UniversityWonsan 999093DPR Korea College of Life Science Kim Hyong Jik University of EducationPyongyang 99903DPR Korea Zhejiang Mariculture Research Institute Wenzhou 325005China

Although the immunomodulatory activity of bamboo vinegar and charcoal powder(BVC)has been increasingly documented in domestic animals,the use of BVC as immunostimulant in fi sh aquaculture awaits verifi *** the present study,the immunostimulatory impacts of dietary BVC intake were investigated in an important aquaculture fi sh species,the African catfi sh Clarias *** show that the pathogen resistance of African catfi sh was signifi cantly improved by dietary BVC intake at the tested levels(0.5%-2%),as indicated by higher survival rates(approximately 1.52-1.85 times that without BVC supplementation)upon intraperitoneally injection of bacterial pathogen Aeromonas *** addition,both the count and phagocytic activity of blood cells were signifi cantly up-regulated by a 45-day dietary supplementation of ***,compared to that of the control,fi sh individuals fed BVC containing diets exhibited signifi cant higher activities of superoxide dismutase(SOD),myeloperoxidase(MPO),and lysozyme(LYZ).The content of immunoglobulin M(IgM)in serum of African catfi sh was also induced by dietary BVC ***,the expression levels of interleukin-8(IL-8),toll-like receptor 1 and 5(TLR1 and TLR5),myeloid diff erentiation factor 88(MyD88),and nuclear factor kappa B(NFκB)in the head kidney were signifi cantly *** fi ndings indicate BVC could be an eff ective immunostimulant in teleost species,which may enhance fi sh immunity through improving hematic parameters,activating bioactive humoral molecules,and up-regulating immune related molecular pathways.

关键词： bamboo vinegar and charcoal powder(BVC) African catfi sh immunostimulant pathogen resistance