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Optimization of a High Speed Spinning Disk Spindle System for Minimum RRO,NRRO,and Lightweight by Using G.A.

厦门大学学报(自然科学版) 2002年第S1期41卷 89-90页

作者： y H Choi S T kim K C yoon J M kim y J Kang Dept.of Mechanical Design and Manufacturing Changwon National UniversityKyungnam 641-773Korea Dept.of Mechanical Engineering Changwon National UniversityKyungnam 641-773Korea Senoir Research Engineer R&D Cente FAGHANWHA Bearing Corp.Kyungnam 641-020Korea Graduate Student Dept.of Mechanical Design and ManufacturingChangwon National UniversityKyungnam 6412773Korea

Law level of RRO(Repeatable Run Out),NRRO(Non Repe at able Run Out),and lightweight construction are a major trend in the high-speed HDD(Hard Disk Drive)sytem to reduce track misregestration and to achieve high track density,which lead to succeed in the ***,it is not easy to r educe RRO,NRRO,and the weight of the spinning disk spindle system efficiently because lightweight construction and or bearing stiffness changes often yields a decrease in the static and dynamic stiffness of the system,and consequently hi gh vibrations may be generated as a ***,it is of importance to e valuate in advance the accurate dynamic behavior of the high speed spinning disk spindle system of a HDD *** study introduces an optimum design of the high speed spinning disk spindle system of a HDD for minimum RRO,NRRO,and lightweight construction using a gene tic *** spinning disk,hub,and bearing components of a HDD system ar e modelled as appropriate finite elements respectively and their equations of mo tion are derived to construct the system equations of the whole spinning disk sp indle system of the HDD *** RRO and NRRO responses of the spinning disk,due to exciting forces arised from ball bearing faults and rotating unbalance,are *** the design optimation,the hub thickness,the disk thickness,bearing positio ns(or bearing span)and bearing stiffness were set as design *** uni que objective function is obtained by multiplying an appropriate weighting facto r by multi-objective functions,such as RRO,NRRO,and the total weight of HDD the *** constraints are maximum RRO limit,maximum weight linit,and the critical speed limit of the HDD spindle *** show that the RRO,NRRO,and weight are reduced by 6%,66.7%and 28%r espectively compared with the initial design of the HDD ***,thi s present study can be used for an optimum design of the spinning disk spindle s ystem of a HDD for lightweight construction

关键词： design optimization genetic algorithm multiobjective optimization repeatable run out non repeatable run out

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The Effect of Reflector with Sound-Absorbing Material on Supersonic Jet Noise

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Journal of Thermal Science 2005年第1期14卷 22-27页

作者： y.-H.KWEON M.TSUCHIDA y.MIyAZATO T.AOKI H.-D.kim T.SETOGUCHI Department of Energy and Environmental Engineering Kyushu University Kasuga 816-8580Japan School of Mechanical Engineering Andong National University Andong 760-749Korea Department of Mechanical Engineering Saga University Saga 840-8502Japan

This paper describes an experimental work to investigate the effect of a reflector on supersonic jet noise radiated from a convergent-divergent nozzle with a design Mach number *** the present study,a metal reflector and reflectors made of three different sound-absorbing materials(grass wool and polyurethane foam)were employed,and the reflector size was *** measurement is carried out to obtain the acoustic characteristics such as frequency,amplitude of screech tone and overall sound pressure level(OASPL).A high-quality schlieren optical system is used to visualize the detailed structure of supersonic *** results obtained show that the acoustic characteristics of supersonic jet noise are strongly dependent upon the jet pressure ratio and the reflector *** is also found that the reflector with sound-absorbing material reduces the screech tone amplitude by about 5-13dB and the overall sound pressure levels by about 2-5dB,compared with those of the metal reflector.

关键词： supersonic jet supersonic jet noise screech tone OASPL reflector sound-absorbing material.

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Design of small-area multi-bit antifuse-type 1 kbit OTP memory

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Journal of Central South University 2009年第3期16卷 467-473页

作者：李龙镇 LEE J H kim T H JIN K H PARK M H HA P B kim y H Department of Electronic Engineering Changwon National University Department of Computer Science and Technology Yanbian University

A multi-bit antifuse-type one-time programmable （OTP） memory is designed, which has a smaller area and a shorter programming time compared with the conventional single-bit antifuse-type OTP memory. While the conventional antifuse-type OTP memory can store a bit per cell, a proposed OTP memory can store two consecutive bits per cell through a data compression technique. The 1 kbit OTP memory designed with Magnachip 0.18 μm CMOS （complementary metal-oxide semiconductor） process is 34% smaller than the conventional single-bit antifuse-type OTP memory since the sizes of cell array and row decoder are reduced. And the programming time of the proposed OTP memory is nearly 50% smaller than that of the conventional counterpart since two consecutive bytes can be compressed and programmed into eight OTP cells at once. The layout area is 214 μm× 327 μ,, and the read current is simulated to be 30.4 μA.

关键词： multi-bit OTP programming time antifuse memory data compression

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Retrieval of the Single Scattering Albedo of Asian Dust Mixed with Pollutants Using Lidar Observations

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Advances in Atmospheric Sciences 2014年第6期31卷 1417-1426页

作者： Sungkyun SHIN young Min NOH Kwonho LEE Hanlim LEE Detlef MLLER y.J.kim Kwanchul kim Dongho SHIN School of Environmental Science and Engineering Gwangju Institute of Science and TechnologyKorea Department of Geoinformatics Engineering Kyungil UniversityKorea Department of Spatial Information Engineering Pukyong National UniversityKorea Science System and Applications Inc. NASA Langley Research CenterUSA University of Hertfordshire United Kingdom

The vertical distribution of single scattering albedos （SSAs） of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju （35.10°N,126.53°E）.Vertical profiles of both backscatter and extinction coefficients for dust and non-dust aerosols were extracted from a mixed Asian dust plume using the depolarization ratio from lidar *** profiles of backscatter and extinction coefficients of non-dust particles were input into an inversion algorithm to retrieve the SSAs of non-dust *** aerosol layers at different heights had different light-absorbing *** SSAs of non-dust particles at each height varied with aerosol type,which was either urban/industrial pollutants from China transported over long distances at high altitude,or regional/local pollutants from the Korean *** advantage of independent profiles of SSAs of non-dust particles,vertical profiles of SSAs of Asian dust mixed with pollutants were estimated for the first time,with a new approach suggested in this study using an empirical determination of the SSA of pure *** SSAs of the Asian dust-pollutants mixture within the planetary boundary layer （PBL） were in the range 0.88-0.91,while the values above the PBL were in the range 0.76-0.87,with a very low mean value of 0.76 ± *** total mixed dust plume SSAs in each aerosol layer were integrated over height for comparison with results from the Aerosol Robotics Network （AERONET） *** of SSA retrieved from lidar observations of 0.92 ± 0.01 were in good agreement with the results from AERONET measurements.

关键词： lidar Asian dust depolarization ratio microphysical properties single scattering albedo

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Probiotic effects on intestinal fermentation patterns in patients with irritable bowel syndrome

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World Journal of Gastroenterology 2008年第32期14卷 5020-5024页

作者： Jacqueline S Barrett kim EK Canale richard B Gearry Peter M Irving Peter R Gibson Monash University Department of Medicine and Department of Gastroenterology Box Hill Hospital

AIM： To determine whether Lactobacillus casei strain Shirota （yakult） can alter small intestinal bacterial overgrowth （SIBO）, as tested by the lactulose breath test, and whether this is associated with changes in symptoms in irritable bowel syndrome （IBS）. METHODS： 18 patients with IBS （Rome Ⅱ criteria）, who showed an early rise in breath hydrogen with lactulose （ERBHAL）, consumed 65 mL of yakult daily for 6 wk. Lactulose breath test was repeated at the end of the treatment period. Symptoms were recorded daily using a 10 cm visual analogue scale. RESULTS： 14 patients completed the study, 9 （64%） had reversal of ERBHAL, with the median time of first rise in breath hydrogen increasing from 45 to 75 min （P = 0.03）. There was no significant improvement in the symptom score with probiotic therapy, except for wind （P = 0.04）. Patients commencing with at least moderate symptoms and who no longer had ERBHAL at the end of treatment, showed improvement in the overall symptoms scores [median final score 5.3 （IQR 3.9-5.9）, 55% reduction; n = 6] to a greater extent than those who had had persisting ERBHAL [final score 6.9 （5.0-7.0）, 12% reduction; n = 5; P = 0.18]. CONCLUSION： yakult is effective in altering fermentation patterns in the small bowel, consistent with reducing SIBO. The loss of ERBHAL was associated with reduced symptoms. The true interpretation of these findings awaits a randornised, controlled trial.

关键词： Probiotics Small intestinal bacterial overgrowth Breath hydrogen testing Functional gut symptoms

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Time-Lapse 3-D Seismic Wave Simulation via the Generalized Multiscale Finite Element Method

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Communications in Computational Physics 2020年第6期28卷 401-423页

作者： yongchae Cho richard L.Gibson,Jr. Hyunmin kim Mikhail Artemyev yalchin Efendiev Shell International Exploration&Production Inc. 150 N Dairy Ashford RoadHoustonTX 77079USA Department of Geology&Geophysics Texas A&M UniversityCollege StationTexas 77843-3115USA Shell Exploration&Production Company 701 Poydras StreetNew OrleansLA 70139USA Arista Networks DublinIreland Department of Mathematics Texas A&M UniversityCollege StationTexas 77843-3368USA Multiscale Model Reduction Laboratory North-Eastern Federal UniversityYakutskRepublic of Sakha 677980Russia

Numerical solution of time-lapse seismic monitoring problems can be challenging due to the presence of finely layered *** wave modeling using fine layered meshes also adds more computational *** approaches such as finite difference and finite element methods may be prohibitively expensive if the whole domain is discretized with the cells corresponding to the grid in the reservoir subdomain.A common approach in this case is to use homogenization techniques to upscale properties of subsurface media and assign the background properties to coarser grid;however,inappropriate application of upscaling might result in a distortion of the model,which hinders accurate monitoring of the fluid change in *** this work,we instead investigate capabilities of a multiscale method that can deal with fine scale heterogeneities of the reservoir layer and more coarsely meshed rock properties in the surrounding domains in the same *** address the 3-D wave problems,we also demonstrate how the multiscale wave modeling technique can detect the changes caused by fluid movement while the hydrocarbon production activity proceeds.

关键词： Fluid simulation time lapse Generalized multiscale finite element elastic wave

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EFFECT OF CARBON AND BORON ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF A SINGLE CRySTAL SUPERALLOy RR 2072

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Acta Metallurgica Sinica(English Letters) 2005年第1期18卷 33-38页

作者： D.H.kim D.H.ye J.H.Lee y.S.yoo C.y.Jo High Temperature Materials Laboratory Korea Institute of Machinery&Materials 66 SangnamChangwonKyungnam 640-010S.Korea Dept.of Metallurgy Changwon National Univerisity 9 SarimChagwonKyungnam 640-773S.Korea

Carbon and boron have been considered to strengthen grain boundaries that might form during single crystal *** this study the effect of boron on solidification behavior and creep properties of the carbon doped single crystal RR 2072 has been *** order to understand solidification behavior with boron addition,the solid/liquid interface morphology and solidification microstructure were examined with solidification *** relationship between mi-crostructural evolution and creep properties of the carbon and boron modified single crystal has been also investigated.

关键词： single crystal superalloy defect tolerance directional solidification creep rupture

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Suction Performance and Internal Flow of a 2-Bladed Helical Inducer with Inlet Asymmetric Plate

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Journal of Thermal Science 2013年第5期22卷 395-403页

作者： S.Watanabe y.Uchinono K.Ishizaka A.Furukawa J.-H.kim Department of Mechanical Engineering Kyushu University744 Motooka Nishi-ku Fukuoka 819-0395 Japan Graduate School of Engineering Kyushu University744 Motooka Nishi-ku Fukuoka 819-0395 Japan Oita National College of Technology Hyosung Goodsprings Co. Ltd.Korea

It has been found in our past studies that the installation of asymmetric plate at the inlet of inducer is effective for the suppression of cavitation surge *** the present study,the suction performance of 2-bladed helical inducer with an inlet asymmetric plate is experimentally *** is observed that the suction performance in large flow rate conditions is not significantly influenced by the asymmetric plate,whereas the head of inducer with the asymmetric plate increases just before the head breakdown in partial flow *** understand the mechanism of this additional head,the flow measurements and the numerical simulations are carried *** is found that the circumferential component of absolute velocity at the exit of inducer slightly increases with the development of cavitation in both cases with and without the inlet asymmetric plate,indicating the increase of the theoretical *** theoretical head increase with the inlet asymmetric plate is also confirmed by the unsteady numerical simulations,suggesting that the additional head is achieved through the increase of the theoretical head with the change of the exiting flow from the inducer associated with some amount of cavitation.

关键词： Inducer Cavitation Suction performance Internal flow Inlet asymmetric plate

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Development of mathematical model with a genetic algorithm for automatic arc welding process

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Acta Metallurgica Sinica(English Letters) 2010年第3期23卷 230-240页

作者： D.T.Thao I.S.kim J.W.Jeong J.H.Lee J.y.Shim H.H.kim Department of Mechanical Engineering Mokpo National University

This paper is to represent new algorithms to predict process parameters on top-bead width in robotic gas metal arc（GMA） welding *** models have been developed：linear, curvilinear and intelligent model based on full factorial design with two *** analysis was employed for optimization of the coefficients of linear and curvilinear models, while genetic algorithm（GA） was utilized to estimate the coefficients of an intelligent *** only the fitting of these models were checked and compared by using a variance test（ANOVA）, but also the prediction on top-bead width using the developed models were carried out based on the additional *** developed models were employed to investigate the characteristic between process parameters and top-bead *** solutions and graphical representation showed that the intelligent model developed can be employed for prediction of bead geometry in GMA welding process.

关键词： Top-bead width Genetic algorithm Multiple regression Robotic arc welding GMA welding

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Microstructure and creep properties of Mg-4Al-2Sn-1(Ca,Sr) alloys

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1184-1191页

作者： B.H.kim K.C.PARK y.H.PARK I.M.PARK Department of Material Science and Engineering Pusan National UniversitySan 30 Jangjeon-dongGeumjeong-guBusan 609-735Korea

The effects of Ca and Sr addition on the microstructure and creep properties of Mg-4Al-2Sn alloys were examined. Tensile tests at 25 ℃ and 200 ℃ and creep tests at 150 ℃ and 200 ℃ were carried out to estimate the room temperature and high temperature mechanical properties of these alloys. The microstrueture of the Mg-4Al-2Sn alloy showed dendritic a-Mg, Mg17Al12 and Mg2Sn phases. The latter two phases precipitated along the grain boundaries. The addition of Ca and Sr resulted in the formation of ternary CaMgSn and SrMgSn phases within the grain. The grain size was reduced slightly with the addition of Sr and Ca. The tensile strength was decreased by the addition of Ca and Sr at room temperature. However, the high temperature tensile strength was increased. The creep strength was improved by the addition of Ca and Sr.

关键词： magnesium alloys Ca Sr void initiation mechanical properties creep mechanism

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