• Title/Summary/Keyword: sliding-type bearing

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Assesment on the Characteristics of Foundation Bearing Capacity in Reinforced Soil Wall Structure of Large Scale (대규모 보강토옹벽 구조물에서의 기초지반 지지력특성 평가)

  • Han, Jung-Geun;Yoo, Seung-Kyung;Cho, Sam-Deuk;Lee, Kyang-Woo;Hong, Ki-Kwon
    • Journal of the Korean Geosynthetics Society
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    • v.5 no.1
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    • pp.9-14
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    • 2006
  • The reinforced soil retaining wall structures of serious types with environmental are widely expanding more and more in Korea, which divided conventional type's reinforced soil retaining wall on segmental retaining wall. The causes of most crack occurred at block in reinforced soil retaining wall structure caused by the differential settlement of foundation. It is difference of settlement for significant factor that with overall slope stability. In this study, design assessment of foundation bearing capacity related to differential settlement of foundation ground was considered. And, also, through case study, the countermeasure methods and its application were suggested that the bearing capacity of foundation had to stabilize. The foundation ground in charge of bearing capacity should be affected by the resisting force of sliding, because the foundation parts of reinforced soil retaining wall were belongs to potential slope sliding area in overall stabilizing including retaining wall structures. Therefore, the analyzing or the designing of bearing capacity for foundation should be considered control capacity on the overall slope sliding.

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Analysis on the frictional loss of a bent-axis type hydraulic piston pump (사축식 유압 펌프의 마찰손실 해석)

  • Hong, Yeh-Sun;Doh, Yoon-Ho
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1548-1553
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    • 2003
  • The design of a high speed axial piston pump for hydrostatic transmission systems requires specific understanding on where and how much its internal frictional and flow losses are generated. In this study, the frictional loss of a bentaxis type hydraulic piston pump was analyzed in order to find out which design factors influence the mechanical efficiency most significantly. To this end, the friction coefficients of the sliding components were experimentally identified by a specially constructed tribometer. Applying them to the three-dimensional dynamic model of the pump presented by Doh and Hong [1], the friction torques generated by the sliding components such as piston head , bearing and valve plate were theoretically computed. The accuracy of the computed results was confirmed by the comparison with the experimentally measured mechanical efficiency. In this paper, it is shown that the viscous friction on the valve plate and the drive shaft bearing is the primary sources of the frictional losses of the bent-axis type pump, while the friction forces on the piston contribute to them only slightly.

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Internal Flow Characteristic Analysis and Deformation of Foil Considering Slip between Foils (Foil사이의 미끄러짐을 고려한 Foil Bearing변형 및 내부유동특성해석)

  • Lee, S.H.;Won, C.S.;Hur, N.;Jeon, S.B.
    • 유체기계공업학회:학술대회논문집
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    • 2001.11a
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    • pp.482-487
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    • 2001
  • Leaf type foil bearings have been used successfully in many aerospace applications such as air cycle machines, turbocompressors and turboexpander. These applications are characterized by light loads, constant speeds and low to moderate temperatures. But, as system on start-up or shutdown, sliding contact between the shaft and foil surfaces cause wear. So, in present study, to understand pressure-flow characteristics and deformation of foil bearing, flow/structure interaction analysis was used. and using this method, 2D and 3D calculation was peformed for shape of foil bearing to know circumferential direction flow and leakage flow characteristics of axial direction.

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Actuating Characteristics of Electrostatic Micro-motors

  • Kim, Young-Cheol;Kim, Byung-Ok
    • 연구논문집
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    • s.33
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    • pp.53-65
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    • 2003
  • Electrostatic micro-motors can be divided into three classes: (i) salient type side drive motor, (ii) radial gap type wobble motor, (iii) axial gap type wobble motor. The working mechanism, torque evaluation, fabrication, and operational characteristics of each micro motors are compared. It is proved that axial gap type wobble motor has the bigger generating torque than that of the other type. The gear ratio of wobble motors increases the driving torque at the cost of a decreasing angular speed and decreases the friction because of the rolling motion instead of sliding at the bearing. Techniques for characterizing micro-motors performance are presented.

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Dry sliding wear behavior of plain low carbon dual phase steel by strain hardening and oxidation (가공경화와 산화층 형성에 의한 이상조직 저탄소강의 건식 미끄럼 마멸 거동)

  • Yu, H.S.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.05a
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    • pp.149-152
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    • 2006
  • Dry sliding wear behavior of low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the dual phase steel was compared with that of a plain carbon steel which was normalized at $950^{\circ}C$ for 30min and then air-cooled. Dry sliding wear tests were carried out using a pin-on-disk type tester at various loads of 1N to 10N under a constant sliding speed condition of 0.2m/sec against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss measured to the accuracy of $10^{-5}g$ by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and a profilomter. Micro vickers hardness values of the cross section of worn surface were measured to analyze strain hardening behavior underneath the wearing surfaces. The were rate of the dual phase steel was lower than the plain carbon steel. Oxidation on the sliding surface and strain hardening were attributed for the higher wear resistance of the dual phase steel.

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A Study on the Friction and Wear Characteristics of $Al_2O_3-TiC$ ($Al_2O_3-TiC$의 마찰 및 마모특성에 관한 연구)

  • 조구환;이기현;김경웅
    • Tribology and Lubricants
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    • v.8 no.2
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    • pp.20-25
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    • 1992
  • Friction and wear behavior of hot isostatic pressed $Al_2O_3-TiC$ was experimentally examined. Pin-on-disk type friction and wear apparatus was designed and manufactured for the experiment. The experiments were conducted under unlubricated sliding motion in both low and high humidity for three kinds of sliding speed. $Al_2O_3-TiC$ and bearing steel were used as counterface materials. Friction coefficient, wear rate, and surface roughness were measured. Wear surface and wear debris were observed through optical microscope and SEM and analyzed by EDAX. The results showed that the counterface materials, the sliding speed, and the moisture at the sliding surface have significant influence on the friction coefficient and wear rate of $Al_2O_3-TiC$.

Sliding Wear Mechanism of Ultra-Fine Grained Low Carbon Dual Phase Steel as n Function of Applied Load (결정립 미세화에 따른 이상조직 탄소강의 하중에 따른 마멸 기구)

  • Yu, H.S.;Yi, S.K.;Shin, D.H.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.421-424
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    • 2007
  • Dry sliding wear behavior of ultra-fine grained (UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.

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Sliding Wear Mechanism of Ultra-Fine Grained Low Carbon Dual Phase Steel as a Function of Applied Load (경정립 미세화에 따른 이상조직 탄소강의 하중에 따른 마멸기구)

  • Yu, H.S.;Yi, S.K.;Shin, D.H.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.16 no.4 s.94
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    • pp.299-303
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    • 2007
  • Dry sliding wear behavior of ultra-fine grained(UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.

Improved Effects of Reinforced Wall with Types of Connection Methods (보강재 연결 유.무에 따른 보강토옹벽의 보강효과)

  • 신은철;최찬용
    • Geotechnical Engineering
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    • v.14 no.5
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    • pp.67-76
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    • 1998
  • The commonly used method to secure the stability of reinforced retaining structure is the reinfocement of backfill with connection attached or unattached to the geogrid type wall. Laboratory model tests for both cartes were conducted to investigate the effectiveness of geogridreinforcement, length of reinforcement inclusion, failure envelop, and the relationships between the face wall displacement and vertical settlement. The bearing capacity of each case was also determined. According to the model test results, geogrid-reinforced rigid wall is very effective for increasing the bearing capacity and reducing the displacement of retaining wall. The observed sliding line of model test is similar to the theoretical one.

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Transmission characteristics of nonlinear torsional vibration of a rotating system with magnet coupling (평판 자기결합 회전장치의 비선형 비틀림 진동 전달 특성)

  • 서상준;전오성;은희준
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.5
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    • pp.593-600
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    • 1986
  • In direct contact power transmission from primary driver to a secondary follower system, one of the important problems is the vibration transmission. In some applications the reduction of vibration level at the follower as low as possible is utmost important. The magnetically coupled power transmission system is often used for this purpose. In this paper, we report the results of a study on the nonlinear torsional vibration transmission characteristics of the rotating system with face-type magnet coupling. The equation of motion is solved analytically up to 3rd harmonics. The frictional force of the sliding bearing which is used to support the follower shaft is considered as the damping term. Numerical calculations are carried out by the Newton-Raphson method, and the calculated results are compared with the experiment for face-type magnet coupling. The experimental result shows that the reasonant frequency of the magnet coupling is very low and is in good agreement with the theoretical result when the average damping constant per unit area of the sliding bearing is 0.5kg*f*sec/cm$^{3}$.