• Title/Summary/Keyword: Rigid Bearing

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An Study of Behavior of Granuler soil for the Piled raft from the Model Test (모형실험을 이용한 사질토지반에서의 Piled raft 거동특성에 대한 연구)

  • Kwon, Oh-Kyun;Lee, Whoal;Kim, Jin-Bok;Lee, Seung-Hyun;Oh, Se-Boong
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.10a
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    • pp.358-365
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    • 2002
  • In this paper the model tests have been conducted and the results were compared with those by the theoretical methods to study the behaviors of the piled raft. The size of model box is 2.2m${\times}$2m${\times}$2m. The raft is made of rigid steel plate and piles are made of steel pipes. Generally the bearing capacity of group piles is designed with only the pile capacities, which is Ignored the bearing capacity of raft. But the uncertainty of pile-raft-soil interaction leads to conservative design ignoring the bearing effects of raft. In the case of considering the bearing capacity of raft, the simple sum of bearing capacity of raft and that of each pile cannot be the bearing capacity of piled raft. Because the pile-raft-soil interaction affects the behavior of piled raft. Thus the effects of pile-raft-soil interaction are very important in the optimal design. In this paper, the behaviors of piled raft are studied through model tests of 2${\times}$2, 2${\times}$3, and 3${\times}$3 pile groups. The spacing between piles is changed in the model tests. And the behaviors of free standing and piled raft are also studied.

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Stability analysis of pump using finite element method (유한요소법에 의한 펌프축계의 안정성해석)

  • 양보석
    • Journal of Advanced Marine Engineering and Technology
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    • v.10 no.4
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    • pp.31-40
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    • 1986
  • With the tendency toward high speed and high pressure in centrifugal pumps, the problem of sub-synchronous vibration has arisen, caused by the hydraulic forces of the working fluid, such as wearring, balance piston, impeller, etc.. These forces can drastically alter the rotor critical speeds and stability characteristics, and can be acted significant destabilizing forces. For preventing such self-excited vibration, the desing of the rotor system needs, which would secure the stability of the machine. In this paper, a procedure is presented for dynamic modeling of rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter finite rotor elements and discrete bearings, seals and impellers. A finite element model including the effects of rotatory inertia and gyroscopic moments is developed using the consistent matrix approach. The technique of dynamic matrix reduction is applied to the shaft matrices to reduce them to a set of matrices of dynamic of significantly fewer degrees of freedom. The representation of bearing, seal and impeller elements is in term of linearized stiffness and damping matrices by reasonably small perturbations from equilibrium. The stability behavior of a typical double suction centrifugal pump is presented. Results show the influence of clearance and flow conditions on running speeds and stability characteristics.

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A Study on Development of Forming Roller for Metal Ball Manufacturing Process for Machine Parts (기계부품용 금속구 제조공정의 성형롤러 개발에 관한 연구)

  • Joe H.S.;Park C.K.;Kim Y.H.;Kim Y.H.;Park C.W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1686-1690
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    • 2005
  • Although metal ball can be used as parts of bearing or metal filter, that is used by single product with solder ball or shot ball. Also, according as demand of metal ball of various diameter increase, processing property 솜 extension of coverage are important. Especially an optimal design of cutting roller was investigated for determining appropriate dimensions of components of manufacturing system. In this study, the effects of the diameter and the round radius of cutting roller were calculated and analyzed. We applied data of rigid-plastic FEM Simulation in basis design of equipment to solve these issues, and confirmed processing factor about metal ball manufacturing process that use cutting process of metal wire in this research

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Process Analysis and Design in Forming of Bearing Rings by the FEM (유한요소법을 활용한 궤도륜의 프레스 성형공정 설계)

  • 강범수;이진희;변상규;최한호;김완두
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1994.03a
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    • pp.80-91
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    • 1994
  • This study aims detecting forming defects for the forming process of bearing rings, which is designed by an industry expert. The designed process consists of one forming operation for the outer ring and four operations for the inner ring. The thickness of the sheet used is 1.6mm, and is in between of thin sheet and bulk material. Here the rigid-plastic finite element method is applied to the analysis and design of the process without considering anisotropy of thin sheet. Thinning and folding defects are detected if the initially designed process is applied for manufacturing. so a new process is designed by referring the results of the FEM. It is confirmed that the industry expert agree the possibility of defects derived from FEM results.

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Process Analysis and Design in Forming of Bearing Rings by the FEM (유한요소법을 활용한 궤도륜의 프레스 성형공정 설계)

  • 강범수;이진희;변상규;최한호;김완두
    • Transactions of Materials Processing
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    • v.3 no.2
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    • pp.189-201
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    • 1994
  • This study aims detecting forming defects for the forming process of bearing rings, which is designed by and industry expert. The designed process consists of one forming operation for the outer ring and four operations for the inner ring. The thickness of the sheet used is 1.6mm, and is in between of thin sheet and bulk material. Here the rigid-plastic finite element method is applied to the analysis and design of the process without considering anisotropy of thin sheet. Thinning and folding defects are detected if the initially designed process is applied for manufacturing. So a new process is designed by referring the results of the FEM. It is confirmed that the industry expert agree the possibility of defects derived from FEM results.

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A Control of an Active Magnetic Bearing System (능동형 자기베어링 시스템의 제어)

  • Kim, Jong-Moon;Park, Min-Kook;Kim, Seog-Joo
    • Proceedings of the KIEE Conference
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    • 2003.04a
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    • pp.75-78
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    • 2003
  • In this paper, an active magnetic bearing-based motor-generator(M-G) system is designed and controlled using a digital PID control concept. The plant dynamics consisting of actuator and rigid rotor dynamics are described. And some experiments are conducted with each global control and local control concept. From the whirl test, the M-G set can be controlled within about ${\pm}10{\mu}m$ gap variation at the rotational speed of 6000rpm.

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Elasto-Hydrodynamic Lubrication Characteristics of Bump Foil Bearings (범프포일베어링의 탄성유체윤활 특성)

  • Kim, Young-Cheol;Lee, Dong-Hyun;Kim, Kyung-Woong
    • 유체기계공업학회:학술대회논문집
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    • 2004.12a
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    • pp.98-103
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    • 2004
  • This paper presents modeling and simulation of the bump foil bearings with consideration of the elastic behavior of the foil and gas compressibility. Heshmat had originally introduced the simple compliance model to estimate the EHL(elasto-hydrodynamic lubrication) performance. But this approach can not consider the deflection of top foil at the edge of bearing, so model is insufficient to analyze in case that the eccentricity ratio is greater than I. So the top foil is considered as a simple beam model supported by linear spring elements, and the bump foil deflection can be simple compliance model. The EHL calculations are performed for convention rigid type, classical foil type, variable pitch type and double bump type toil bearings. This paper presents that 2nd or 3rd generation bearings have excellent performance in every speeds.

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Control of Non-Contact Bearing-Based Motor-Generator System (비접촉 베어링 지지 모터-발전기 시스템의 제어)

  • Kim, Jong-Moon;Kang, Do-Hyun;Park, Min-Kook
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.861-863
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    • 2003
  • In this paper, a controller for a non-contact bearing-based motor-generator system is designed. The levitation control method is a digital PID control. The plant dynamics consisting of actuator and rigid rotor dynamics are described. And some experiments are conducted with each global control and local control concept. From the whirl test, the Motor-Generator System can be controlled within about ${\pm}10{\mu}m$ gap variation at the rotational speed of 600rpm and generate electric power of AC100V.

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LMI-based $H_\infty$ Robust Control of Asymmetric Rotor-magnetic Bearing System (비대칭 로터-자기베어링 시스템의 LMI에 기초한 $H_\infty$ 강건제어)

  • 강호식;송오섭
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.3
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    • pp.172-179
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    • 2003
  • Linear matrix Inequality based $H_\infty$ robust controller is designed to control the motion of a 4-axis unbalanced rigid asymmetric rotor supported and controlled by two active magnetic bearings in this paper. To this end, the equations of motion of the system are derived via Hamilton's variational principle and transformed to a state-space form for the standard $H_\infty$ control problem. LMI-based controller, which does not require additional assumptions beyond the usual stabilizability and detectability assumptions, is designed based upon the pole place weighting function and loopshaping technique. The obtained results are compared with those reported in the available literature and the efficiency of the proposed LMI-based $H_\infty$ control is revealed.

$H_{\infty}$ Control of Magnetic Bearing-Rotor System : LMI- based approaches (자기베어링-로터시스템의 LMI 접근법에 의한 $H_{\infty}$ 제어기 설계)

  • 박충남;송오섭;강호식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.948-953
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    • 2001
  • Nonlinear dynamic equation of a 4-axis rigid rotor supported by two an-isotropic magnetic bearings is derived via Hamilton's principle. It is transformed to a state-space form for the standard Η$_{\infty}$ control problem. we present a robust Η$_{\infty}$ control design methods of continuous and discrete LMI-based approaches and improve performance using loopshaping.

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