• Transactions on Electrical and Electronic Materials
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• 제6권6호
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• pp.249-255
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• 2005

In recent years, a novel tiny piezoelectric linear motor converting a radial mode vibration to a longitudinal mode vibration driven by the impact force has been developed for a camera optical module. The tiny piezoelectric motor is consisted of a shaft, mobile element, and piezoelectric transducer. In this work, the frictional coefficient and static friction force of the interface between the shaft and the mobile element have been investigated according to their respective materials. It was found that two combinations, namely Pyrex glass or stainless steel for the shaft and stainless steel (SUS) for the mobile element, exhibited good dynamic behaviors in the tiny ultrasonic linear motor, which was newly developed based on operating concepts based on Newton's law.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.82-90
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• 1998

Machines that normally operate under fluid film lubricated condition also experience surface damage. This is largely due to the failure of the lubricant film which leads to boundary lubrication. Thus, it is important to have a good understanding of boundary lubrication behavior. In this paper the major tribological parameters that influence the boundary lubrication properties are evaluated. It is shown that disk roughness, hardness and normal load affect the friction and wear of metals in boundary lubrication. Also, the mechanism of surface damage is attributed to abrasion and wear particle interaction.

• Tribology and Lubricants
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• 제17권2호
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• pp.97-108
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• 2001

This paper describes the development of performance analysis technique for a leaf-type gas lubricated fail bearing. Stiffness coefficient and frictional damping due to the slip between all contacts of leaves are evaluated for various leaf structures. The fluid film thickness and pressure distribution are computed but it is not considered the elastic deformation by film pressure. The analysis results include the effects that the curvature radius and the length of leaf and the friction coefficient have on the static and dynamic characteristics of the foil bearings.

• Tribology and Lubricants
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• 제11권5호
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• pp.177-183
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• 1995

Recent work with phosphate esters has shown that a lubricious polymeric film can formed from the vapor phase on interacting during and sliding. This lubrication technique has led to methods to reduce friction and wear to very low values at high temperatures up to 700$^{\circ}$C. Preliminary with synthetic tri aryl phosphates are very promising. The vaporized lubricant forms a polymeric film on the sliding and rolling surfaces reducing the coefficient of friction below 0.05. In-situ formation of the polymeric films shows that the polymer that is formed on the surface exists in different states depending on surface temperature.

• 한국정밀공학회지
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• 제20권4호
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• pp.143-150
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• 2003

Frictional properties of ultra-thin carbon coatings on silicon wafer were investigated based on Taguchi experimental design method. Sensitivity analysis was performed with normal load, relative humidity, deposition process, and coating thickness as the variables. It was found that despite low thickness, the carbon coating resulted in relatively low friction coefficient. Also, the frictional behavior was affected significantly by humidity and normal load.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.436-440
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• 2013

An haptic tactile interface (HTI) is presented with its modeling. Its design is dedicated to perform friction coefficient measurement to characterize reachable feelings with that kind of interface. Friction measurements are presented and discussed.

• Tribology and Lubricants
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• 제15권2호
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• pp.178-183
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• 1999

This paper presents friction and wear related results of thermite and gas pressure welded rails under various environmental contact conditions. A welded rail which was fabricated by thermite welding and gas pressure one has been tested over full range of test conditions in a pin-on-disk wear testing machine. The results show that the friction coefficient and wear rates of a welded rail are heavily dependent on the contact pressures and sliding environments for two welding methods such as thermite and gas pressure weldings.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.89-92
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• 2003

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging from 10nN to 100nN. At low applied loads, a ridge pattern was formed on the PMMA surface. No wear particles were observed during the pattern-forming mild wear. At high applied loads, severe wear occurred accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the Scratching was closely related with surface deformation of the film.

• Tribology and Lubricants
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• 제9권2호
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• pp.36-48
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• 1993

This study is concerned with the changes (deterioration) of the mechanical properties of used oil in the gasoline engine. The analysed properties of used oil were friction, antiwear, wear debris, load-carrying ability and the formation of surface film. From this study, it was found that the oil used in engine was deteriorated to increase the wear and fricion and decrease the load-carrying ability as the running distance of oil was increased. Also the main cause of deterioration was related to the formation of the protective film on the contact zone. When the film was composed with rich additives (sulfur), this could properly protect contact zone from the increase of wear and friction. But as oil was deteriorated, it could not form such a film and therefore the protective ability of sliding surface diminished.

• 반도체디스플레이기술학회지
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• 제3권1호
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• pp.15-20
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• 2004

Through shallow trench isolation (STI) chemical mechanical polishing (CMP) tests, we investigated the dependence of pad surface temperature on the abrasive and additive concentrations in ceria slurry under varying pressure using blanket film wafers. The pad surface temperature after CMP increased with the abrasive concentration and decreased with the additive concentration in slurries for the constant down pressure. A possible mechanism is that the additive adsorbed on the film surfaces during polishing decreases the friction coefficient, hence the pad surface temperature gets lower with increasing the additive concentration. This difference in temperature was more remarkable for the higher concentration of abrasives. In addition, in-situ measurement of spindle motor was carried out during oxide and nitride polishing. The averaged motor current for oxide film was higher than that for nitride film, meaning the higher friction coefficient.