• KSTLE International Journal
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• v.1 no.2
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• pp.107-112
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• 2000

In case of the limitation of Deep RIE fabrication far Micro Gas Turbine, bearing aspect ratio is limited in very small value. The characteristics such as pressure distribution, load capacity and non-linearity of a short bearing of L/D=0.083 and a conventional bearing of L/D=1.0 with coupled boundary effects are investigated for Micro Gas Turbine bearings. The coupled effect was analyzed by mass conservation at coupled end area. The results, increasing load capacity and non-linearity due to the coupled effect of thrust and journal bearing, are obtained and the selection of journal bearing type is discussed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.243-249
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• 2000

In case of the limitation of Deep RIE fabrication for Micro Gas Turbine, bearing aspect ratio is limited in very small value. The characteristics such as pressure distribution load capacity and non-linearity of a short bearing of L/D=0.083 and a conventional bearing of L/D=1.0 with coupled boundary effects are investigated far Micro Gas Tlubine bearings. The coupled efffect was analyzed by mass conservation at coupled end area. The results, increasing load capacity and non-linearity due to the coupled effect of thrust and journal bearing, are obtained and the selection of journal bearing type is discussed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.29-35
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• 2013

The pitch reducer consists of several planetary gearsets, and they should have good load distribution over gear tooth flank and load sharing among the planets to improve the durability. This work investigates how bearing internal clearances influence both the load distribution over the gear tooth flank and the planet load sharing. A whole system model is developed to analyze a pitch reducer. The model includes non-linear mesh stiffness of gears, non-linear stiffness of bearings. The results indicate that the face load factor and mesh load factor decrease, and the fatigue life of output shaft bearings increase as bearing internal clearances of output shaft decrease. Therefore, the internal clearance of output shaft bearing must be considered when designing the pitch reducer for wind turbines.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6322-6328
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• 2014

Finite element analyses were performed to find out the load bearing behavior of three kinds of shallow foundations. The analysis results for strip footing showed that local shear failure mode could be observed for a zero dilatancy angle and general shear failure mode could be seen for non-zero dilatancy angles. The ultimate bearing loads for non-zero dilatancy angles were approximately 1.5 times higher than that of a zero dilatancy angle. General shear failure mode was observed for circular footing and square footing regardless of the dilatancy angle. The ultimate bearing loads for a non-zero dilatancy angle were slightly greater than that for a zero dilatancy angle. A comparison of the load-settlement curves for three kinds of footing showed that the load bearing capacities for non-zero dilatancy angle were greater than those for a zero-dilatancy angle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.2
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• pp.224-234
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• 1997

It was demonstrated earlier that for laminar, isothermal flow of the lubricant in long journal bearings, inertia has negligible effect on the load carrying capacity and influences only the stability characteristics of the bearing. The question in the present paper is: 'will these conclusions of the isothermal theory remain valid in the presence of significant dissipation, or will lubricant inertia and dissipation interact non-linearly to bring about qualitative changes in bearing performance\ulcorner' The results obtained here assert that the effect of lubricant inertia on load carrying capacity remains negligible, irrespective of the rate of dissipation. The stability of the bearing is, however, affected by lubricant inertia. These results, although obtained here for long bearings with Sommerfeld and Gumbel boundary conditions, are believed to be applicable to practical bearing operations and affirm that bearing load may be calculated from classical, i. e., non-inertial theory.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.3
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• pp.278-286
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• 2015

The effects of the main bearing stiffness combined with vertical non-torque force on the input load and shaft deflection of a gearbox were investigated for the three-point suspension drive train of a wind turbine. A finite element analysis model for the drive train was studied experimentally, and its applicability to the present study was verified. The results show that, as the main bearing stiffness is increased, the input load of the gearbox decreases, whereas the input shaft deflection increases. The stiffness component for the pitch moment has the largest influence on the gearbox input load. Although the gearbox life increases at a higher main bearing stiffness, the economic efficiency and durability of the entire drive train system should also be considered in the selection of the main bearing stiffness.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.101-110
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• 2007

In order to investigate the effect of the pile shape on the bearing capacity of non-displacement piles, a series of model pile load tests were performed using a calibration chamber and three model piles with different shape. Results of the model tests showed that the bearing capacity of tapered piles was affected by its taper angle as well as the stress states and relative density of soil. Based on the results of model pile load tests, a new design equation for estimation of the bearing capacity of non-displacement piles was proposed, and it takes into account the effect of the taper angles on the bearing capacity of non-displacement piles.

• Journal of the Korean Wood Science and Technology
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• v.43 no.5
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• pp.652-660
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• 2015

To study the bearing characteristics of glass fiber reinforced glulam for structural design, bearing strength tests were performed. Bearing loads were applied in the direction parallel to the grains, and the holes were prepared in such a way that the bolts would bear and support all the layers. The yield bearing strengths of the glass fiber reinforced glulam were found to be similar to those of the non-reinforced glulam, and were almost constant regardless of increases in bolt diameter. The ratio of the experimental yield bearing strength to the estimated bearing strength according to the suggested equation of the Korea Building Code and National Design Specification was 0.91~1.03. For the non-reinforced glulam and the sheet glass fiber reinforced plastic glulam, the maximum bearing load was measured according to the splitting fracture of specimens under bolt. The textile glass fiber reinforced glulam underwent only an embedding failure caused by the bearing load. The failure mode of reinforced glulam according to bearing load will influence the failure behavior of bolted connection, and estimating the shear yield strength of the bolted connection of the reinforced glulam is necessary, not only by using the bearing strength characteristics but also using the fracture toughness of the reinforced glulam.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.5.2-5.2
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• 2010

인체 경조직인 뼈와 치아는 콜라겐 단백질과 인산칼슘 무기질 성분으로 구성된 최적의 복합체라 볼 수 있다. 이러한 인산칼슘 무기질 성분은 결정학적, 화학적으로 hydroxyapatite (HA, Ca10(PO4)6(OH)2)와 거의 유사하여 높은 생체활성과 골전도성을 보이는 것으로 알려져 있다. 또한, hydroxyapatite의 고온 분해 산물로 볼 수 있는 tricalcuim phosphate(TCP, Ca3(PO4)2)는 체내에 이식시 체액에 용해되어 신생골을 유도하는 생체흡수성 세라믹스로 알려져있다. 이러한 HA와 TCP는 우수한 생체친화성에도 불구하고 기계적 특성이 낮아, non-load bearing 부위에 적용이 되어 다공질의 골수복재 용도로 활용되거나, load-bearing부위의 적용을 위한 금속 implant 등의 생체친화성 보완을 위한 표면 코팅재로 사용되고 있는 실정이다. 본 발표에서는 생체특성이 매우 우수한 인산칼슘 생체세라믹스의 load-bearing part 적용을 위하여 강도 및 파괴인성의 기계적 특성을 증진시킨 사례를 살펴보고, non-load bearing part에 실제 사용되는 인산칼슘 생체세라믹스의 다공질(porous) 골수복재(bone graft)의 역학 특성 증진을 위한 아이디어와 함께, 역학 특성이 매우 뛰어난 지르코니아 생체세라믹스의 강화-소결법에 대하여 소개하고자 한다.

• Tribology and Lubricants
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• v.36 no.2
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• pp.82-87
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• 2020

In thrust bearings, the thrust collar and bearing surface need to be parallel to each other to ensure that all pads share the same load. In rotating machines, the shaft system cannot achieve perfect alignment. Misalignment of the thrust collar results in some pads supporting a higher load than others and excessive loads being placed on some pads. Consequently, high loads and high temperatures may occur in the bearing. Thus, in this study, we aim to analytically evaluate the performance of a misaligned non-equalizing direct lubricated tilting pad thrust bearing. We define the oil film thickness of the misaligned thrust bearing using the Byrant angle. Additionally, we calculate the pressure distribution and temperature distribution of the thrust bearing using the generalized Reynolds equation and energy equation. The design limit of the thrust bearing is defined by the load and temperature. Therefore, we evaluate the allowable misalignment angle as the limit of the maximum load and temperature. The analysis results demonstrate that an increase in the speed and load corresponds to a smaller allowable misalignment angle. However, as this is not the same for all thrust bearings, evaluating the allowable misalignment angle at each thrust bearing is essential.