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Development of twin wheel creep-feed grinding machine using continuous dressing for machining of aircraft rotary wing

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Journal of Central South University 2011年第3期18卷 704-710页

作者： KIM Jin-seob HWANG Jong-dae jung yoon-gyo School of Mechatronics Changwon National University

The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-feed *** order to develop such a machine,3D-modeling and machine simulations were performed and a twin wheel creep-feed grinding machine was ***,the axisymmetric precision of the machined workpieces through practical machining was evaluated and the quality of the continuous dressing effect of the developed machine was *** addition,experimental considerations for a proper dresser-to-wheel speed ratio and proper feed rate of the dresser were carried *** a result,a twin wheel creep-feed grinding machine with continuous dressing is developed through machine simulation,manufacturing and performance *** condition for the dresser feed rate is 0.3μm/*** cases of large dressor-to-wheel speed ratio,grinding efficiency can be enhanced,but the surface roughness shows a conflicting *** twin wheel creep-feed grinding machine has satisfactory appraisal with regard to surface roughness,flatness,and *** surface roughness below 0.1μm can be obtained for the blade of ***,in order to perform precise machining,it is necessary to improve the structure of the twin wheel creep-feed grinding machine.

关键词： creep-feed grinding twin wheel surface roughness grinding force continuous dressing flatness parallelism

Development of practical postprocessor for 5-axis machine tool with non-orthogonal rotary axes

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Journal of Central South University 2011年第1期18卷 159-164页

作者： jung Hyoun-Chul HWANG Jong-Dae PARK Ki-Beom jung yoon-gyo School of Mechatronics Changwon National University

In order to develop a practical postprocessor for 5-axis machine tool,the general equations of numerically controlled(NC) data for 5-axis configurations with non-orthogonal rotary axes were exactly expressed by the inverse kinematics,and a windows-based postprocessor written with Visual Basic was developed according to the proposed *** developed postprocessor is a general system suitable for all kinds of 5-axis machines with orthogonal and non-orthogonal rotary *** implementation of the developed postprocessor and verification by a cutting simulation and machining experiment,the effectiveness of the proposed algorithm is *** is improved by allowing exchange of data formats such as rotational total center position(RTCP) controlled NC data,vector post NC data,and program object file(POF) cutter location(CL) data,and convenience is increased by adding the function of work-piece origin ***,a practical post-processor for 5-axis machining is developed.

关键词： post-processor 5-axis machining non-orthogonal rotary axes numerically controlled (NC) data CL data

Continuity control method of cutter posture vector for efficient five-axis machining

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Journal of Central South University 2011年第6期18卷 1969-1975页

作者： HWANG Jong-dae KIM Sang-myung jung Hyun-chul jung yoon-gyo School of Mechatronics Changwon National University

During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.

关键词： five-axis control machining configuration-space B-spline continuity control method impeller interference

Development of tool-path generation module for 5-axis control machining of impellers

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Journal of Central South University 2012年第12期19卷 3424-3429页

作者： jung Hyoun-chul SON Hwang-jin jung yoon-gyo School of Mechatronics Changwon National UniversityChangwon 641-773Korea

An impeller is difficult to machine because of severe collision due to the complex shape,overlapping and twisted shape of the impeller ***,most computer aided manufacturing(CAM)software companies have developed CAM module for manufacturing impeller according to their CAM *** these dedicated modules are difficult to use for inexperienced *** purpose of this work is to develop a tool-path generation module for *** this purpose,it is based on Visual Basic language and used CATIA graphical *** result of simulation for generated tool-path by the module is *** it has slow processing speed compared to other commercial modules,but it is easy to use.

关键词： impeller computer aided manufacturing 5-axis control machining tool path module

Computing Resource Allocation for Blockchain-Based Mobile Edge Computing

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 863-885页

作者： Wanbo Zhang Yuqi Fan Jun Zhang Xu Ding jung yoon Kim School of Computer Science and Information Engineering Intelligent Interconnected Systems Laboratory of Anhui ProvinceHefei University of TechnologyHefei230601China Anhui Province Key Lab of Aerospace Structural Parts Forming Technology and Equipment Hefei University of TechnologyHefei230009China College of Future Industry Gachon UniversitySeongnam13120South Korea

Users and edge servers are not fullymutually trusted inmobile edge computing(MEC),and hence blockchain can be introduced to provide *** blockchain-basedMEC,each edge server functions as a node in bothMEC and blockchain,processing users’tasks and then uploading the task related information to the *** is,each edge server runs both users’offloaded tasks and blockchain tasks *** that there is a trade-off between the resource allocation for MEC and blockchain ***,the allocation of the resources of edge servers to the blockchain and theMEC is crucial for the processing delay of blockchain-based *** of the existing research tackles the problem of resource allocation in either blockchain or MEC,which leads to unfavorable performance of the blockchain-based MEC *** this paper,we study how to allocate the computing resources of edge servers to the MEC and blockchain tasks with the aimtominimize the total systemprocessing *** the problem,we propose a computing resource Allocation algorithmfor Blockchain-based MEC(ABM)which utilizes the Slater’s condition,Karush-Kuhn-Tucker(KKT)conditions,partial derivatives of the Lagrangian function and subgradient projection method to obtain the *** results show that ABM converges and effectively reduces the processing delay of blockchain-based MEC.

关键词： Mobile edge computing blockchain resource allocation

Efficacy of adjuvant mitomycin-C and triamcinoloneimpregnated nasal packing for endoscopic dacryocystorhinostomy

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International Journal of Ophthalmology(English edition) 2024年第3期17卷 480-484页

作者： Sang yoon Kim Christopher B Chambers jung Hyo Ahn Department of Ophthalmology Pusan National University Yangsan HospitalPusan National University School of MedicineResearch Institute for Convergence of Biomedical Science and TechnologyYangsanGyeongnam 50612Republic of Korea Department of Ophthalmology Harborview Medical CenterUniversity of Washington MedicineSeattleWashington 98109USA

●AIM:To compare the success rate and complications of adjuvant use of mitomycin C and triamcinoloneimpregnated biodegradable nasal packing(TABP)in endoscopic dacryocystorhinostomy(DCR).And to evaluate the efficacy of combining intraoperative mitomycin C and TABP for endoscopic DCR.●METHODS:A total of 198 eyes of 148 patients who underwent endoscopic DCR for acquired nasolacrimal duct obstruction were retrospectively *** patients were randomly divided into three groups:Group A included patients treated without intraoperative mitomycin C but with TABP,Group B included patients treated without triamcinolone but with intraoperative mitomycin C and normal saline-impregnated nasal packing,and Group C included patients treated with intraoperative mitomycin C and TABP.●RESULTS:The results revealed no significant difference in the overall success rates between Groups A(86.8%)and B(89.2%;P=0.377).However,Group C(97.5%)showed a significantly higher overall success rate than Groups A and *** incidence of granulomas was significantly lower in group C(5%)than in Groups A(20.8%)and B(15.2%;P=0.009).Other complications,such as crust,synechiae,and revision surgery,did not differ significantly among the three groups.●CONCLUSION:The combination of intraoperative mitomycin C and TABP effectively prevents granulomas and enhances surgical success ***,there is no statistically significant difference observed between the use of mitomycin C or TABP alone.

关键词： dacryocystorhinostomy endoscopic mitomycin C triamcinolone biodegradable

Effects of Initial and Boundary Conditions on Heavy Rainfall Simulation over the Yellow Sea and the Korean Peninsula:Comparison of ECMWF and NCEP Analysis Data Effects and Verification with Dropsonde Observation

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Advances in Atmospheric Sciences 2024年第9期41卷 1787-1803页

作者： Jiwon HWANG Dong-Hyun CHA Donghyuck yoon Tae-Young GOO Sueng-Pil jung Department of Civil Urban Earth and Environmental Engineering Ulsan National Institute of Science and TechnologyUlsan 44919South Korea Program in Atmospheric and Oceanic Sciences Princeton UniversityPrincetonNew Jersey 08544USA National Institute of Meteorological Sciences NIMSJeju 63568South Korea

This study evaluated the simulation performance of mesoscale convective system(MCS)-induced precipitation,focusing on three selected cases that originated from the Yellow Sea and propagated toward the Korean *** evaluation was conducted for the European Centre for Medium-Range Weather Forecasts(ECMWF)and National Centers for Environmental Prediction(NCEP)analysis data,as well as the simulation result using them as initial and lateral boundary conditions for the Weather Research and Forecasting ***,temperature and humidity profiles from 3D dropsonde observations from the National Center for Meteorological Science of the Korea Meteorological Administration served as validation *** showed that the ECMWF analysis consistently had smaller errors compared to the NCEP analysis,which exhibited a cold and dry bias in the lower levels below 850 *** model,in terms of the precipitation simulations,particularly for high-intensity precipitation over the Yellow Sea,demonstrated higher accuracy when applying ECMWF analysis data as the initial *** advantage also positively influenced the simulation of rainfall events on the Korean Peninsula by reasonably inducing convective-favorable thermodynamic features(i.e.,warm and humid lower-level atmosphere)over the Yellow *** conclusion,this study provides specific information about two global analysis datasets and their impacts on MCS-induced heavy rainfall simulation by employing dropsonde observation ***,it suggests the need to enhance the initial field for MCS-induced heavy rainfall simulation and the applicability of assimilating dropsonde data for this purpose in the future.

关键词： initial conditions dropsonde heavy rainfall forecast global model analysis evaluation

Predictive modeling of critical temperatures in magnesium compounds using transfer learning

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Journal of Magnesium and Alloys 2024年第4期12卷 1540-1553页

作者： Surjeet Kumar Russlan Jaafreh Subhajit Dutta jung Hyeon Yoo Santiago Pereznieto Kotiba Hamad Dae Ho yoon School of Advanced Materials Science&Engineering Sungkyunkwan University Suwon 16419Republic of Korea

This study presents a transfer learning approach for discovering potential Mg-based superconductors utilizing a comprehensive target ***,a large source dataset(Bandgap dataset)comprising approximately∼75k compounds is utilized for pretraining,followed by fine-tuning with a smaller Critical Temperature(T_(c))dataset containing∼300 ***,there is a significant improvement in the performance of the transfer learning model over the traditional deep learning(DL)model in predicting ***,the transfer learning model is applied to predict the properties of approximately 150k *** are validated computationally using density functional theory(DFT)calculations based on lattice dynamics-related ***,to demonstrate the extended predictive capability of the transfer learning model for new materials,a pool of virtual compounds derived from prototype crystal structures from the Materials Project(MP)database is generated.T_(c) predictions are obtained for∼3600 virtual compounds,which underwent screening for electroneutrality and thermodynamic *** Extra Trees-based model is trained to utilize E_(hull)values to obtain thermodynamically stable materials,employing a dataset containing Ehull values for approximately 150k materials for *** with Ehull values exceeding 5 meV/atom were filtered out,resulting in a refined list of potential Mg-based *** study showcases the effectiveness of transfer learning in predicting superconducting properties and highlights its potential for accelerating the discovery of Mg-based materials in the field of superconductivity.

关键词： Superconductivity Critical temperature Transfer learning Crystal structure features Thermodynamic stability

Confluence of ZnO and PTFE Binder for Enhancing Performance of Thin-Film Lithium-Ion Batteries

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Energy & Environmental Materials 2024年第5期7卷 52-60页

作者： Subhashree Behera Swathi Ippili Venkatraju Jella Na-Yeong Kim Seong Cheol Jang Ji-Won jung Soon-Gil yoon Hyun-Suk Kim Department of Materials Science and Engineering Chungnam National University School of Materials Science and Engineering University of Ulsan Department of Energy and Materials Engineering Dongguk University

Developing anode materials with high specific capacity and cycling stability is vital for improving thin-film lithium-ion batteries. Thin-film zinc oxide （ZnO）holds promise due to its high specific capacity, but it suffers from volume changes and structural stress during cycling, leading to poor battery performance. In this research, we ingeniously combined polytetrafluoroethylene （PTFE） with ZnO using a radio frequency （RF）magnetron co-sputtering method, ensuring a strong bond in the thin-film composite electrode. PTFE effectively reduced stress on the active material and mitigated volume change effects during Li+ion intercalation and deintercalation. The composite thin films are thoroughly characterized using advanced techniques such as X-ray diffraction, scanning electron microscopy,and X-ray photoelectron spectroscopy for investigating correlations between material properties and electrochemical behaviors. Notably, the ZnO/PTFE thin-film electrode demonstrated an impressive specific capacity of1305 mAh g-1(=7116 mAh cm-3) at a 0.5C rate and a remarkable capacity retention of 82%from the 1st to the 100th cycle, surpassing the bare ZnO thin film （50%）. This study provides valuable insights into using binders to stabilize active materials in thin-film batteries, enhancing battery performance.

关键词： li-ion batteries metal oxides anodes polytetrafluoroethylene (PTFE) thin films