• Title/Summary/Keyword: journal bearing

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The Effect of Aerated Oil Considering Live Oil Surface Tension on High-Speed Journal Bearing

  • Chun, Sang-Myung
    • KSTLE International Journal
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    • v.2 no.2
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    • pp.103-113
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    • 2001
  • The influence of aerated oil on high-speed journal bearing is examined by classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The live oil surface tension is considered as functions of temperature, API gravity and air volume ratio. With changing eccentricity ratio, it is investigated the effects of air bubbles on the performance of a high-speed plain journal bearing. Just at the moderate eccentricity ratios, even if the involved aeration levels are not so severe and the entrained air bubble sizes are not so small, it is found that the bearing load and friction farce may be changed so visibly for the high speed bearing operation.

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The Effect of Eccentricity on Aerated Oil in High-Speed Journal Bearing

  • Chun, Sang Myung
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.1-11
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    • 2001
  • The influence of aerated oil on a high-speed journal bearing is examined by classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. With changing eccentricity ratio, it is investigated the effects of air bubbles on the performance of a high-speed plain journal bearing. Just at the moderate eccentricity ratios, even if the involved aeration levels are not so severe and the entrained air bubble sizes are not so small, it is found that the bearing load and friction force may be changed so visibly for the high speed bearing operation.

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An Experimental Study on the Pressure and Temperature Distribution in a Plain Journal Bearing (저어널베어링의 압력 및 온도분포에 관한 실험적 연구)

  • 신영재;김경웅
    • Tribology and Lubricants
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    • v.4 no.1
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    • pp.69-73
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    • 1988
  • The effects of journal speed and bearing load on pressure distribution and the temperature distribution of bearing surface are investigated experimentally. The journal bearing which has 219.94mm diameter, length-to-diameter ratio of L/D=0.8 and clearance ratio of 0.004 is used. Journal has a built-in pressure transducer for the measurement of pressure distribution in the mid plane of bearing. Bearing surface temperatures are measured at 60 points. The bearing load is varied from 300 N to 5900 N and journal speed from 300 rpm to 2500 rpm. As the load is increased under constant speed, the location of maximum pressure moves to the site of minimum film thickness, and maximum pressure and absolute value of minimum pressure are increased. The temperature distribution in vicinity of oil inlet shows that heated lubricant's carry-over exists around the oil inlet.

Proportional and Derivative Control of Hydrodynamic Journal Bearings (동압 베어링의 비례 및 미분 제어)

  • 노병후;김경웅
    • Tribology and Lubricants
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    • v.17 no.4
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    • pp.283-289
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    • 2001
  • The paper presents the stability characteristics of a rotor-bearing system supported by actively controlled hydrodynamic journal bearing. The proportional and derivative controls including coupled motion are adopted for the control algorithm to control the hydrodynamic journal bearing with a circumferentially groove. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than a conventional analysis which uses the Reynolds condition. The stability characteristics of a rotor-bearing system supported by actively controlled hydrodynamic journal bearing are investigated for various control gains with the Routh-Hurwitz criteria using the linear dynamic coefficients which are obtained from the perturbation method. It is found that the speed at onset of the instability is increased for both proportional and derivative control of the bearing. It is also found that the proportional and derivative control of the coupled motion is more effective than that of the uncoupled motion.

The Effects of Early Weight Bearing and Vibration Exercise on Disuse Osteoporpsis in Stroke Patients (조기 체중부하 및 진자운동이 뇌졸중 환자의 무용성 골다공증에 미치는 영향)

  • Kang Jeong-IL
    • The Journal of Korean Physical Therapy
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    • v.17 no.1
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    • pp.27-42
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    • 2005
  • This study aims to investigate the effect of Early Weight Bearing and Vibration Exercise and is focusing on the difference between changes if experimental before and after on 30 stroke patients. The obtained results are as follows; First, the chang due to Early Weight Bearing and Vibration in the comparison of experimental duration, Early Weight Bearing and Vibration Exercise showed improvement of Bone Density(P<.05). Second, in the comparison of change according to Early Weight Bearing and Vibration Exercise, Bone Density was significantly changed between two experimental group(P<.05). Third, the chang due to Early Welght Bearing and Vibration Exercise, Bone Density of sound femoral head and affected femoral head was significantly changed(P<.05). Fourth, the chang due to Early Weight Bearing and Vibration Exercise, Bone Density of femoral head was significantly changed between two experimental group(P<.05).

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Bearing Load Distribution Studies in a Multi Bearing Rotor System and a Remote Computing Method Based on the Internet

  • Yang, Zhao-Jian;Peng, Ze-Jun;Kim, Seock-Sam
    • Journal of Mechanical Science and Technology
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    • v.18 no.6
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    • pp.946-954
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    • 2004
  • A model in the form of a Bearing Load Distribution (BLD) matrix in the Multi Bearing Rotor System (MBRS) is established by a transfer matrix equation with the consideration of a bearing load, elevation and uniform load distribution. The concept of Bearing Load Sensitivity (BLS) is proposed and matrices for load and elevation sensitivity are obtained. In order to share MBRS design resources on the Internet with remote customers, the basic principle of Remote Computing (RC) based on the Internet is introduced ; the RC of the BLD and BLS is achieved by Microsoft Active Server Pages (ASP) technology.

A Study on the Correction and Management of Bearing Drawings in the Defense Field (국방분야 베어링 도면정비 및 관리방안 연구)

  • Yi, Il-Lang;Kim, Tae-Won
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.2_2
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    • pp.225-232
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    • 2020
  • In this paper, we introduce the results of investigating and overhauling bearing drawings in the defense field, and propose an effective bearing drawing management system. We identify the features and performance items that must be regulated in the bearing drawing. After reviewing the validity of the bearing drawings, we classify the incorrect drawings by factor. To achieve greater effect, standardized formats are needed to incorporate into the drawing in the early stage. We propose the introduction of a bearing drawing management system so that the developing bearing technology can be applied quickly to the defense sector. As other elementary parts of the machine have similar problems, we think this study will help develop improvement plans.

Stepwise Decision making Methodology Based on Artificial Intelligence: An Application to Bearing Design (인공지능에 기반한 단계적 의사결정방법 : 베어링 설계에의 적용)

  • 서태설;한순홍
    • Korean Journal of Computational Design and Engineering
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    • v.4 no.2
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    • pp.100-109
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    • 1999
  • The bearing design includes the steps of selection bering type, selection bearing subtype, and determining the peripheral equipments. In this paper decision making methodologies are compared to propose a stepwise decision methodology to the bearing selection problem. An artificial neural network trained with design cases is used for selecting a bearing type in the first step. Then the subtype of the bearing is selected using the weighting method, high is a kind of multi-criteria decision making method. Finally, the types of peripheral equipments such as lubrication devices, seals and bearing housings are determined using a rule-based expert system.

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Estimation of the Unmeasured Unbalance Responses and Identification of Bearing Parameters in Flexible Rotor-Bearing Systems (회전체 베어링계의 불균형응답 간접추정과 베어링 매개변수 규명)

  • 홍성욱;이종원
    • Journal of KSNVE
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    • v.2 no.3
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    • pp.193-202
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    • 1992
  • The unbalance response analysis is one of the essential area in the forced vibration analysis of rotor bearing systems because of it usefulness in balancing and diagnosis as well as identification of parameters involved in rotor bearing systems. However some unbalance responses are not measurable due to the fact that rotor bearing systems are often encapsulated by fixtures or safety protectors. In the present paper, an efficent estimation scheme for unmeasured unbalance responses in rotor bearing systems is developed. The fundamental fearture of the proposed method is characterized by the linear formulae to estimate the unbalance responses from the measured unbalance responses and the finite element auxilliary model equation which is constructed to be identical to the prototype excluding the uncertain parameters such as bearing coefficients. The identification formulae for bearing parameters are also derived by using the unbalance response and the finite elements auxiliary model. Simulation is provided to verify the effectiveness of the proposed method.

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The study on the bearing capacity and settlement of a foundation placed over a tunnel (Tunnel 상부지반의 기초 지지력과 침하에 관한 연구)

  • 김수삼;정승용;김용수;권태창
    • Journal of the Korean Society for Railway
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    • v.2 no.4
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    • pp.20-31
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    • 1999
  • When a foundation on the ground with tunnel is constructed, the ultimate bearing capacity of a footing is reduced by tunnel. In practice, structure may bate a considerable damage because of large settlement. This study shows that the settlement which is caused by variety of the ultimated bearing capacity leads fatal damages to the footing above tunnel. Therefore, it is necessary to study on the reduction both of the ultimate bearing capacity which leads a failure and of tolerable settlement which satisfies the safety of the building. For this reason, the variety of ultimated bearing capacity was analyzed using tub-dimensional elasto-plastic finite difference method in this paper. As a result, bearing capacity of the foundation above tunnel should be determined after establishing limit of allowable settlement and considering reduction-ratio of bearing capacity.

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