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FEA technique of hot plate forming process using cell-typed die with cooling device

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中国有色金属学会会刊：英文版 2012年第S3期22卷 831-837页

作者： Jung-Min lee In-Kyu lee Kyung-Hun lee Dae-Soon KIM byung-Min KIM Dongnam Regional Division Korea Institute of Industrial Technology School of Mechanical Engineering Pusan National University Industrial Technology Division Hyundai Heavy Industries

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG ***-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process,and an air-cooling device is separately installed inside the lower die.A finite element analysis (FEA) technique was developed,which included hot forming,air flow,cooling and thermal deformation analysis for the hot plate forming process using the cell-typed ***,the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis.A small-scale model test of the process was conducted to verify the FEA *** analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

关键词： cell-typed die hot plate forming spherical LNG tank heat transfer coefficient

1.45 GPa ultrastrong cryogenic strength with superior impact toughness in the in-situ nano oxide reinforced CrMnFeCoNi high-entropy alloy matrix nanocomposite manufactured by laser powder bed fusion

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Journal of Materials Science & Technology 2022年第2期97卷 10-19页

作者： Young-Kyun Kim Min-chul Kim Kee-Ahn lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Atomic Energy Research Institute(KAERI) Daejeon 34057Republic of Korea

CrMnFeCoNi high-entropy alloys(HEAs)exhibit an excellent combination of tensile strength and ductility at cryogenic *** study led to the introduction of a new method for the development of high-performance CrMnFeCoNi HEAs at cryogenic temperatures by jointly utilizing additive manufacturing(AM)and the addition of interstitial *** interstitial oxygen present in the powder feedstock was transformed into beneficial nano-sized oxides during AM *** HEA nanocomposite fabricated using laser powder bed fusion(L-PBF)not only contains heterogeneous grains and substructures but also a high number density of nano-sized *** tensile results revealed that the L-PBF HEA nanocomposite has superior yield strengths of 0.77 GPa and 1.15 GPa,and tensile strengths of 0.92 GPa and 1.45 GPa at 298 K and 77 K,*** addition,the Charpy impact energies of the samples tested at 298 K and 77 K were measured as 176.2 J and 103.7 J,*** results indicate that the L-PBF HEA nanocomposite successfully overcomes the well-known strength-toughness *** tensile deformation microstructure contained a relatively large number of deformation twins(DTs)at cryogenic temperature,a possible consequence of the decrease in the stacking fault energy with decreasing *** the other hand,cracks were found to propagate along the grain boundaries at room temperature,whereas a transgranular crack was observed at cryogenic temperature in the specimens fractured as a result of the Charpy impact.

关键词： Laser powder bed fusion High-entropy alloy matrix nanocomposite Nano-oxide:cryogenic Tensile Impact toughness

Dynamic Modeling and Experiment of a Fish Robot with a Flexible Tail Fin

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Journal of Bionic Engineering 2013年第1期10卷 39-45页

作者： Phi Luan Nguyen Van Phu Do byung Ryong lee ~ Intelligent Control and Mechatronics Lab School of Mechanical Engineering University of Ulsan Daehak-ro 93 Nam-gu Ulsan 680-749 South Korea School of Mechanical Engineering University of Ulsan Daehak-ro 93 Nam-gu Ulsan 680-749 South Korea

This paper presents the dynamic modeling of a flexible tail for a robotic fish. For this purpose firstly, the flexible tail was simplified as a slewing beam actuated by a driving moment. The governing equation of the flexible tail was derived by using the Euler-Bernoulli theory. In this equation, the resistive forces were estimated as a term analogous to viscous damping. Then, the modal analysis method was applied in order to derive an analytical solution of the governing equation, by which the relationship between the driving moment and the lateral movement of the flexible tail was described. Finally, simulations and experiments were carried out and the results were compared to verify the accuracy of the dynamic model. It was proved that the dynamic model of a fish robot with a flexible tail fin well explains the real behavior of robotic fish in underwater environment.

关键词： robotic fish flexible tail dynamic modeling lateral movement

Thrust and Swimming Speed Analysis of Fish Robot with Non-uniform Flexible Tail

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Journal of Bionic Engineering 2016年第1期13卷 73-83页

作者： Phi Luan Nguyen byung Ryong lee Kyoung Kwan Ahn School of Mechanical Engineering University of Ulsan Ulsan Korea

We present a dynamic model of a fish robot with a Non-uniform Flexible Tail （NFT）. We investigate the tendencies of the thrust and swimming speed when the input driving moment changes. Based on the proposed dynamic model of the NFT, we derive the thrust estimation, equation of motion, and performance evaluation of a fish robot with a NFT. By defining the optimal stiffness of the NFT in simulation, a fish robot prototype is then designed and fabricated. A series of experiments are performed to verify the proposed model. Experiment results are in good agreement with simulation data. The results show that the thrust and swimming speed of the fish robot are proportional to the amplitude of the driving moment. There are two resonant fre- quencies （f = 1.4 Hz and 2.2 Hz）, the maximum thrust and swimming speed （about 0.7 BL.s-1） are found to be around f = 1.4 Hz. The above results inidicate the proposed model is suitable for predicting the behavior, thrust and swimming speed of a fish robot with a NFT.

关键词： fish robot flexible tail dynamic modeling swimming speed thrust Froude efficiency

Propulsive Velocity Optimization of 3-Joint Fish Robot Using Genetic-Hill Climbing Algorithm

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Journal of Bionic Engineering 2009年第4期6卷 415-429页

作者： Tuong Quan Vo Hyoung Seok Kim byung Ryong lee School of Mechanical and Automotive Engineering University of UlsanSan 29Muger 2-dongNam-guUlsan 680-749Korea

Underwater robot is a new research field which is emerging quickly in recent *** researches in this field focus on Remotely Operated Vehicles(ROVs),Autonomous Underwater Vehicles(AUVs),underwater manipulators,*** robot, which is a new type of underwater biomimetic robot,has attracted great attention because of its silence in moving and energy efficiency compared to conventional propeller-oriented propulsive mechanism. However,most of researches on fish robots have been carried out via empirical or experimental approaches,not based on dynamic *** this paper,we proposed an analytical optimization approach which can guarantee the maximum propulsive velocity of fish robot in the given parametric ***,a dynamic model of 3-joint(4 links)carangiform fish robot is derived,using which the influences of parameters of input torque functions,such as amplitude,frequency and phase difference,on its velocity are investigated by ***,the maximum velocity of the fish robot is optimized by combining Genetic Algorithm(GA)and Hill Climbing Algorithm(HCA).GA is used to generate the initial optimal parameters of the input functions of the ***,the parameters are optimized again by HCA to ensure that the final set of parameters is the'near'global ***,both simulations and primitive experiments are carried out to prove the feasibility of the proposed method.

关键词： fish robot carangiform velocity optimization propulsive model

Dynamic Modeling of a Non-Uniform Flexible Tail for a Robotic Fish

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Journal of Bionic Engineering 2013年第2期10卷 201-209页

作者： Phi Luan Nguyen Van Phu Do byung Ryong lee Intelligent Control and Mechatronics Lab School of Mechanical Engineering University of Ulsan Ulsan 680-749 Korea School of Mechanical Engineering University of Ulsan Ulsan 680-749 Korea

In this paper, a non-uniform flexible tail of a fish robot was presented and the dynamic model was developed. In this model, the non-uniform flexible tail was modeled by a rotary slender beam. The hydrodynamics forces, including the reactive force and resistive force, were analyzed in order to derive the governing equation. This equation is a fourth-order in space and second-order in time Partial Differential Equation （PDE） of the lateral movement function. The coefficients of this PDE were not constants because of the non-uniform beams, so they were approximated by exponential functions in order to obtain an analytical solution. This solution describes the lateral movement of the flexible tail as a function of material, geometrical and actuator properties. Experiments were then carried out and compared to simulations. It was proved that the proposed model is suitable for predicting the real behavior of fish robots.

关键词： fish robot flexible tail dynamic modeling kinematic lateral movement

EMMS drag model for simulating a gas-solid fluidized bed of geldart B particles: Effect of bed model parameters and polydisperity

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Particuology 2020年第4期18卷 142-154页

作者： Krishnadash SKshetrimayum Seongho Park Chonghun Han chul-Jin lee School of Chemical Engineering and Materials Science Chung-Ang University06974 SeoulSouth Korea School of Chemical and Biological Engineering Seoul National UniversitySan 56-1Shillim-dongKwanak-guSeoul151-742South Korea

The energy minimization multi-scale(EMMS)is a heterogeneous drag model widely used to simulate gas-solid fluidized *** this work,we conducted computational fluid dynamics simulations of a gas-solid fluidized bed for Geldart B particles to compare the EMMS with the homogeneous Gidaspow drag *** results from both the homogeneous and heterogeneous drag models were compared with literature experimental data on pressure drop and bed *** was no noticeable difference in predicted bed characteristics in the slugging ***,in the turbulent regime,the EMMS model predicted slightly lower bed expansion than did the Gidaspow *** evaluated the effects of solid-solid and solid-wall interaction parameters by varying the restitution and specularity *** expansion increases by a factor of 1.05-1.08 when the restitution coefficient increases from 0.9 to *** models predict a higher solid volume fraction and higher solid downflow velocity near the wall for a low specularity coefficient of 0.01 or *** we considered solid phases of different sizes to model polydisperity,the simulation predicted vertical segregation of 300,350,and 400μm in the fluidized region due to ***,the drag models made similar predictions in bad characteristics from cold model simulation ofa polysilicon fluidized-bed reactor,although there was very little vertical segregation of solid particles for this case.

关键词： CFD simulation Energy minimization multi-scale drag Gas-solid fluidized bed Polydisperity Fluidized-bed reactor

Neuroprotection by resveratrol-glucuronide and quercetin-glucuronide via binding to polyphenol-and glycosaminoglycan-binding sites in the laminin receptor

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Neural Regeneration Research 2025年第3期20卷 819-820页

作者： Rayudu Gopalakrishna Jennifer Aguilar Emily lee William J.Mack Department of Integrative Anatomical Sciences Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCAUSA Department of Neurological Surgery Keck School of MedicineUniversity of Southern CaliforniaLos AngelesCAUSA

The dietary polyphenolic compounds resveratrol and quercetin prevent neurodegenerative diseases in experimental models;however, they reach the brain only in nanomolar concentrations in the glucuronidated and sulfated ... 详细信息

关键词： resveratrol molar dated

Nanocrystalline low-silica X zeolite as an efficient ion-exchanger enabling fast radioactive strontium capture

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Frontiers of Chemical Science and Engineering 2024年第9期18卷 15-23页

作者： Hyungmin Jeon Susung lee Jeong-chul Kim Minkee Choi Department of Chemical and Biomolecular Engineering(BK21 Four) Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Center for Nanomaterials and Chemical Reactions Institute for Basic Science(IBS)Daejeon 34141Republic of Korea

NaA zeolite(Si/Al=1.00)has been commercially applied for capturing radioactive 90Sr^(2+)because of its high surface charge density,effectively stabilizing the multivalent ***,owing to its narrow micropore opening(4.0Å),large micron-sized crystallites,and bulkiness of hydrated Sr^(2+),the Sr^(2+)exchange over NaA has been limited by very slow *** this study,we synthesized nanocrystalline low-silica X by minimizing a water content in a synthesis gel and utilizing a methyl cellulose hydrogel as a crystal growth *** resulting zeolite exhibited high crystallinity and Al-rich framework(Si/Al of approximately 1.00)with the sole presence of tetrahedral Al sites,which are capable of high Sr^(2+)uptake and ion ***,the zeolite with a FAU topology has a much larger micropore opening size(7.4Å)and a much smaller crystallite size(~340 nm)than NaA,which enable significantly enhanced ion-exchange *** to conventional NaA,the nanocrystalline low-silica X exhibited remarkably increased Sr^(2+)-exchange kinetics(>18-fold larger rate constant)in batch *** both the nanocrystalline low-silica X and NaA exhibited comparable Sr^(2+)capacities under equilibrated conditions,the former demonstrated a 5.5-fold larger breakthrough volume than NaA under dynamic conditions,attributed to its significantly faster Sr^(2+)-exchange kinetics.

关键词： Sr^(2+)removal low-silica X zeolite nanocrystal hydrogel methyl cellulose