• Title/Summary/Keyword: bearing characteristics

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A Study on the Characteristics of Lower Extremity Weight Bearing in Patients with Low Back Pain (요통환자의 기립시 하지체중 지지특성에 관한 연구)

  • Yoon, Hong-Il;Bae, Soo-Chan
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.5 no.1
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    • pp.59-74
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    • 1999

  • 66 patients with low back pain were evaluated to determine if any differences of weight bearing were existed between the same side leg that feel pain(pain side leg) and that without pain (non-pain side leg) of lower extremities while weight bearing. 66 patients were divided into 3 groups according to pain pattern such as low back pain only(26), radiating pain only(21) and low back pain with radiating pain (19). Control group were 28 normal persons. The weight bearing was rated by Limloader(Model LLD-2000, Ver 1.2) and analyzed by paired and independent t-test, one-way ANOVA, Dunan's analaysis and Pearson's correlation analysis. The results of this study were as follows : 1. In patient group, significant difference of weight bearing rating between pain side leg and non-pain side leg was found. There was borne significantly less weight bearing rating(14.68%) on the pain side leg(P<.001). 2. In normal group, there was no significant difference between left and right leg(P>.05). But there was significant difference(3.21%) in absolute difference of both leg(p<.001). 3. The difference of 1 and 2 was 11.47% : more difference of weight bearing rating between both legs in patient group than that of the control group(p<.001). 4. There were significant differences of weight bearing rating in those 3 groups : low back pain group(10.30%), radiating pain group (17.90%) and low back pain with radiating pain group (17.10%) (p<.001). 5. There was significant correlation between pain intensity and difference of weight bearing rating(p<.05). The severer pain intensity. the more difference of weight bearing rating was found. 6. There was no significant correlation between the age, height and duration of symptom, etc(p>.05).

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Study on Fuel Lubrication Performance of a High Speed Rolling Element Bearing (소형 고속 구름베어링의 연료윤활 특성 연구)

  • Kim, Ki-Tae;Kim, Sung-Kyun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.424-426
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    • 2008

  • A parametric study was carried out to find the fuel lubrication performance of high speed small rolling element bearings. Both MIL-PRF-7808 turbine oil and JP-8 aircraft fuel were used as the lubricant to compare the operational characteristics. 17 mm inner diameter deep groove ball bearing and 20 mm cylindrical roller bearing were used. A high speed bearing test rig was developed and the testing was done with varying applied load, cooling air temperature, lubricant flow rate, and speed. Fuel caused more cage wear than oil for ball bearing with increasing axial load and rotational speed. The bearing temperature using fuel was lower than that using oil, and this seems to be the result of the high cooling capacity of fuel. According to various tests, the fuel lubrication is applicable for the lubrication on the main shaft bearings of expendable small gas turbines.

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Numerical investigation of thermo-flow characteristics in BLDC motor (BLDC 모터 내 열.유동 해석)

  • Kim, Min-Soo;Lee, Kwan-Soo
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2540-2545
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    • 2007

  • A computational study of BLDC motor is presented to elucidate thermo-flow characteristics in winding and bearing with heat generation. Rotation of rotor and blades drives influx of ambient air into the rotor inlet and the inflow rates are predicted more at the front-side inlet than at the rear-side, which can be ascribed to the different pressure distribution. Recirculation zone appears in the tiny interfaces between windings, however, showing the enhanced cooling performance due to the higher velocity distribution near the rotor wall. In contrast, flow separation and incline angle of bearing groove, and relatively slower velocity distribution cause poor cooling performance and therefore the redesign of the bearing groove is significantly required.

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