• Proceedings of the Korean Geotechical Society Conference
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• 2002.11a
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• pp.209-236
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• 2002

Ultimate pile capacity - Point resistance - Frictional resistance - Determination of point and frictional resistances from field tests - Summary of recommendations from design Group effects Settlement analysis.

• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.12-17
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• 2004

By using an experimental approach recently developed to determine the torque-tension relationship for bearing frictional characteristics of several typical bolted joints were studied. The experimental approach allows the direct determination of the bearing friction between the nut and its bearing surface. Detailed friction studies were made on the influences of the size and shape of the hole, the use of a slot in a bolted joint, contact area and position, and other factors such as turning speed, coating, and the use of wax on the bearing surface. The contact area and position of the washer have a marginal effect on the bearing friction. The organic coating on the nuts reduces the bearing friction significantly. Nuts with organic coating over a washer with zinc finish provide the smallest and the most consistent bearing friction. The results from the experimental investigation will be helpful for the better design of bolted joints bearing friction. The results from the experimental investigation Will be helpful for the better design of bolted joints.

• Journal of the KSME
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• v.16 no.2
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• pp.122-127
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• 1976

It was reported in the Journal of KSME Vol. 15, No. 3 and No. 4, 1975 that could be finished the best smooth surface by applying frictional work to the metal surface. Even if we can finish the best smooth surface of methal, it is not available when it has not anti-wear. Present study tried to investigate the anti-wear and the characteristics of frictional worked surface by using the sliding contact between plain bearing of brass and frictional worked jornal of mild steel. The results were compared with the case of ground journal.

• 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.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.218-227
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• 1998

Present study is undertaken to optimize the lubrication reliability and frictional loss of the dynamically-loaded journal bearing in hermetic reciprocating compressor with alternative refrigerant R600a application. Thermodynamic and dynamic analysis has been conducted to investigate cylinder pressure variations by substitution alternative refrigerant R600a for R12. The modeling of the dynamics of the compressor mechanism has been performed with lumped mass method. A mathematical model is developed for analyzing the dynamics of the journal bearing system with the mobility method. It takes into account the effects of the refrigerant species, aspect ratio, clearance ratio and surface roughness. A corresponding computer program is described which enables to obtain the minimum film thickness and frictional loss. Design optimization is graphically performed by parametric studies of the aspect ratio and clearance ratio.

• Tribology and Lubricants
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• v.15 no.1
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• pp.108-115
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• 1999

The electrical and frictional properties of oil-impregnated sintered-metal bearing (OSB) and herringbone-grooved fluid bearing (HFB) with varying loads and speeds were measured. OSB shows very good performance up to 20,000 rpm and 0.05 N, and HFB successfully works up to 35,000 rpm and 0.05 N. From the endurance tests on start-stop and continuous operation, it was confirmed that those bearings could be mass-produced fur use on scanner motor in a laser scanner unit.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.151-156
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• 2001

Experimental frictional and wear characteristics of silicon graphite materials is studied in this paper. Those specimens are lubricated with high temperature and highly pressurized water to simulate the same operating condition for the journal bearing and the thrust bearing on the main coolant pump bearing in the newly developing nuclear reactor named SMART(System-integrated Modular Advanced ReacTor). Operating condition of the bearings is realized by the tribometer and the autoclave. Friction coefficient and wear loss are analyzed to choose the best silicon graphite material. Pin on plate test specimens are used and coned disk springs are used to control the applied force on the specimens. Wear loss ana wear width are measured by a precision balance and a micrometer. The friction force is measured by the strain gauge which can be used under high temperature and high pressure. Three kinds of silicon graphite materials are examined and compared with each other, and each material shows similar but different results on frictional and wear characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.359-360
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• 2010

• Tribology and Lubricants
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• v.15 no.1
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• pp.24-28
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• 1999

This paper describes a new pivoting technique to improve bearing performance in pivoted pad thrust bearings. This new technique adjusts the pivot line in a line pivoted pad thrust bearing to be parallel to the trailing edge of a sector shaped pad. Bearing performance factors such as load carrying capacity, frictional torque and flow rate are numerically investigated for conventional point-pivoted and line-pivoted pads and for the new parallel-line pivoting technique. It is shown that the load carving capacity can be maximized with the new technique.

• Journal of the Korean Institute of Rural Architecture
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• v.23 no.3
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• pp.1-8
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• 2021

Rural multi-purpose buildings needs to ensure their safety against various disasters. Therefore, a pile foundation, which is a foundation type that can transmit the load of the structure to the bedrock layer, has been designed. The pile foundation method is largely divided into driving piles method and pre-bored pile method. Recently, in order to respond to the Noise and Vibration Control Act and related environmental complaints, construction of pile foundation adopts pre-bored pile method. The bearing capacity of the pre-bored pile method is calculated through a load test in situ. However, a disadvantage stems in that it is difficult to measure the ultimate bearing capacity due to field conditions. Therefore, in this study, the skin frictional force of pre-bored pile was measured through a model test in laboratory for each pile filling material. In result, the pile filling material with using circulating resources shows superior skin frictional force than ordinary portland cement. This study also judged that the result can be applied in place of ordinary Portland cement in the field.