Chemical nature of nascent metal surfaces which is one of the important active sources for tribochemical reactions was investigated using a newly developed method. Some enhanced activities were observed. For example, organic compounds chemisorbed on nascent gold surfaces and aromatic compounds decomposed on nascent nickel surfaces resulting in hydrogen evolution. Non-polar compounds such as organic sulfides had a higher chemisorption activity on nascent steel surfaces than polar compounds such as fatty acids and phosphates. Organic sulfides reacted directly with nascent steel surfaces and the surface was covered with metal sulfides. The activity for the chemisorption of organic compounds was closely dependent on the electronic structure of metals. Although benzene chemisorbed very easily on nascent surfaces of transition metals, it did not chemisorb ell nascent surfaces of simple metals. Boundary lubricating behaviors of extreme pressure additives were explained on the bases of the chemical activities of nascent surfaces obtained in this investigation. Under mild conditions, polar compounds such as fatty acids and phosphates were effective for boundary lubrication, because surfaces are covered with oxide layers. On the other hand, sulfides were more effective under severe conditions where the oxide layers were removed and the nascent surfaces were formed.

The electric contact resistance between ball and disk was measured to estimate the real area of contact under dry and lubrication conditions. The results from the measured constriction resistance using the hypothesis of a single circular contact was compared with those of Hertzian contact theory and hardness. The resistance correlated well with the asperity contact area and friction when the ball slides on the flat disk spreaded with lubricant film. Therefore, the constriction resistance method was useful to identify the lubrication regimes with respect to various loads and speeds. The results of this work will aid in better prediction of lubrication regimes with respect to the operating conditions.

An experimental study was carried out to investigate the effect of nano-contact condition on the nano-adhesion phenomena. SPM(scanning probe microscope) tips with different radius of curvature were fabricated by a series of masking and etching processes. DLC(diamond-like carbon) and W-DLC (tungsten-incorporated diamond-like carbon) were coated on (100) silicon wafer by PACVD(plasma assisted chemical vapor deposition). Pull-off forces of Pure Si-wafer, DLC and W-DLC were measured with SPM(scanning probe microscope). Also, the same series of tests were carried out with the tips with different radius of curvature. Results showed that DLC and W-DLC showed much lower pull-off force than Si-wafer and Pull-off force increased with the tip radius.

The determination of surface morphology is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe morphology of various rubbed surface, the wear test was carried out under different experimental conditions in lubricating wear. And fractal descriptors was applied to rubbed surface of hydraulic driving material with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Morphology of rubbed surface can be effectively obtained by fractal dimensions.

This investigation has been studied about friction and wear properties which were important problem, when carbon fiber reinforced plastic(CFRP) was used practically. Unidirection carbon fiber reinforced composites was fabricated with epoxy resin matrix and carbon fiber as a reinforced, and its surface was modified by the ion-assisted reaction. And then we tested the their friction and wear properties according to the ion-irradiation. when the amount of ion-irradiation was 1${\times}$10l6$\^$16/ ions/$\textrm{cm}^2$, the friction coefficient values were about 0.1, where as, the friction coefficient values of non-treatment composites were about 0.16. The former was the stablest in wear mode. We know that ion-irradiation was not proportioned to the friction coefficient, so we found the optimal conditions of the friction and wear according to the ion-irradiation.

The effect of the alignment of the contacting bodies is concerned. Tilting of a body (indenter) is regarded as a mis-alignment. Recently developed method fur evaluating the contact normal traction is introduced and discussed, in which piecewise parabolic profile is considered as a generalized contact profile. Indentation by a wedge with rounded apex is solved as an example problem. In the case of partial slip regime, the variation of shear traction is examined during the closed path of shear force by using the efficient numerical technique. Concentration of the slip region is also investigated. By evaluating the energy dissipation from the contact surface, the effect of the mis-alignment-alignment on wear is discussed.

Recently, PM-high speed steel(PM-HSS) has reportedly been a good alternative material for rolling mill because of its superior peformance to conventional HSS. This paper has been aimed to investigate the possibility for application to rolling contact element for PM-HSS by X-ray diffraction technique. The X-ray elastic constant for PM-HSS has been found by X-ray diffraction during the four-point bending test. Residual stress and half-value breadth on the contact surface during rolling contact fatigue process by X-ray diffraction have also been measured. The result of this study shows that the application of X-ray diffraction technique to PM-HSS could be as possible alternative material as conventional HSS. Half-value breadth on rolling contact surface by X-ray diffraction is not changed during rolling contact fatigue process. On the other hand, the residual stress is changed. This suggests that dislocation reaction has been hardly occurred in rolling contact, depending on supersaturated carbon in PM-HSS.

A linear elastic fracture mechanics analysis of multiful subsurface cracks propagation in a half-space subjected to moving thermomechanical surface traction was peformed using the finite element method. The effect of frictional heat at the sliding surface on the crack growth behavior is analyzed in terms of the thermal load and peclet number. The crack propagation direction is predicted in light of the magnitudes of the maximum shear and tensile stress intensity factor ranges. When moving thermomechanical surface traction exists, subsurface horizontal cracks are propagation in-plane crack growth rate at the beginning but they are propagation out-of-plane crack growth rate by the frictional heat which is occurrence by the repeated sliding contact.

An experimental study on the effect of silver particles on the sliding behavior of bearing steels was performed by using a ball-on-disk tribometer. Tests were carried out in ambient air, dry and vacuum. Disks of AISI 52100 were silver-coaled by a thermal evaporation method, and the effects of silver particle transfer on friction were firstly analyzed. In order to understand further the mechanism of silver particles transfer and its effect on friction and wear, pre-compressed silver particles were artificially introduced into the friction interface and the results were compared to those of silver-coated specimens. Results showed that the introduced silver particles produced transfer layers and resulted in low friction. It also showed that this low friction is closely related to the characteristic behavior of transfer layers. Shakedown and rachetting occurred at the friction interface and affected the friction and wear.

The wear behaviors of ultrahigh molecular weight polyethylene pins against titanium alloy and stainless steel disks moving in two different kinematic motion were investigated by conducting repeat pass rotational sliding and linear reciprocal sliding wear tests. Linear reciprocal motion wore more the polyethylene pin than did repeat pass rotational motion for both disk materials. It means that the repeated directional change of contact stresses generates more wear debris in polyethylene. For the linear reciprocal sliding tests, titanium alloy disks were damaged with some scratches after one million cycles but no surface damage was observed on the polyethylene pins. On the other hand, for the repeat pass rotational sliding tests, all titanium alloy disks were severely abraded on the entire region of sliding track. This phenomenon can be interpreted by that stress fatigue under repeated sliding contact initiated titanium oxide layer wear particles from disk surface, and these hard particles were embedded into polyethylene pin and then they severely abraded the disk surface. From these results it can be concluded that the kinematic motion in pin-on-disk wear tests play a crucial role on the wear behaviors of UHMWPE pins against titanium alloy and stainless steel disks.

In case of rough contact fatigue, the accurate calculation of surface tractions is essential to the prediction of crack initiation life. Accurate Surface tractions influencing shear stress amplitude can be obtained by contact analysis based on tile morphology of contact surfaces. In this study, to simulate rough contact under sliding condition, gaussian rough surface generated numerically in the previous study was used and to calculate crack initiation life in the substrate, dislocation pileup theory was used.

The plasma spray technics has known as one of the surface modification methods to improve the mechenical properties or the functional charactristics of materials. This paper has been aimed to investigate the effects of plasma sprayed conditions, such as spray distance and arc power level, on sliding wear properties of plasma sprayed $Al_2$O$_3$-40%TiO$_2$coating layer. The sliding wear test using pin-on-disc type wear machine, has been conducted in several sliding speed for coating layer sparyed under different conditions. The result of this paper is that the wear resistance of plasma sprayed $Al_2$O$_3$-40%TiO$_2$coating layer is fluctuated with tile spray distance and the arc power level. The wear resiatance could be improved with decreasing the spray distance and with increasing the arc power level.

This report describes the results of analysis, synthesis and evaluation of antimony dithiocarbamates (SbDTC). Sb-DTC were synthesized by reacting antimony oxide with dithiocarbamates whish were prepared by reaction of dialkylamines and carbon disulfide. The chemical structures and properties of synthesized Sb-DTCs in lab. were discussed. The frictional properties of SbDTC were tested with Four-Ball Wear Scar Tester and Four-Ball Extreme Tester by ASTM method.

Recently, the population of vehicles using LPG as fuel has been increasing due to relatively low fuel price and low tax. Although gasoline engine oils we usually used to lubricate LPG engines, some troubles such as oil thickening and TBN depletion were found in them under severe operating condition. In order to investigate the deterioration mechanism of lubricants in LPG engine, field trials were performed. The results from the field trials showed that the deterioration of oils in LPG engine is different from that in normal gasoline engine. LPG engine oil was deteriorated mainly through oxidation and nitration at high temperature rather than contamination of fuel combustion products.

As one of the strategies to sustain the maximum output with the total minimum cost, huge plants worldwide, such as steel mills, refineries, petrochemical plants, and etc., may and will plan and implement the minimization of operating and maintenance costs for their own. This paper is to review the foreign cases of energy savings through lubrication improvements as one of the actions for that purpose and summarize their directions, and also to look at one such local test case.

The contaminant seperation performance of fitters has been widely investigated for many years. However, most of the proposed filter assessment techniques have proven disappointing for practical use. Although the Multipass (Beta) Filtration test method (ISO 4572) provides valuable information in assessing fi ters, it has a limitation on evaluating the increasing family of low-flow and high Beta filters. The limitation stems from two main sources: the over simplified theoretical model and the inherently complicated procedure in analysis of data. Hence a new advanced filtration theory, the Beta Prime developed on a draw-down test basis is applied to predict field operating characteristics of a filter for tractor hydraulic systems in this study.

Vapor oil fer radiator fm press in heat exchangers of air conditioners is carefully considered as the cooling performance can be affected by the residual vapor oil on the surface of radiator fin after fin press working. In this work, vapor oil for radiator fin press was developed in consideration of several properties such as physical characteristics, the rate of volatility, hazardous properties and material compatibility. In addition, it was confirmed that radiator fin press workability adopting the vapor oil and the cooling performance of air conditioner using the radiator fin were good.

New engine design changes and ever increasing requirements make the design of gear oils challenging. Proper understanding of fundamental lubrication theory and formulation knowledge is necessary to develop new gear oils. This paper provides an overview on fundamentals of lubrication theory and functions of each additive. Also, key technical issues facing gear oils are discussed.

To improve the vehicle fuel economy, various technologies such as improvement of power train efficiency, use of light weight material, improvement of aerodynamic design, have been studied. One of the possible way to improve the vehicle fuel economy is to reduce the engine friction loss by improving the engine oil characteristics. In the present paper, it was examined the effect of the engine oil viscosity and the addition of friction modifier to engine oil on vehicle fuel economy improvements. Moreover, the effect of engine oil degradation on vehicle fuel economy was examined with two gasoline vehicles and one diesel vehicle by using the fuel economy test facility.

Synthetic water-based metal-cutting fluids are increasingly popular in the metal-working industry because of its environmental friendliness. However, the fluids have the problem to be decomposed by microbes with use. Thus, it is very important to evaluate the stabilities of the fluids against microbes for the excellent fluids. The purpose of this study is to investigate the biodegradability of several lubricating agents used to improve anti-wear property of the fluids. From the study, it was found that there existed some difference on the biodegradability against microbes such as Escherichia coli and Klepsiella pneumoniae depended on the structure of the lubricating agents and pH of the fluids.

In development process of engine lubrication system, many failure cases are related with aeration problem. Therefore, it is very important to clarify the aeration in the engine oil circuit system. As of today, many factors have been introduced as the major cause in the engine oil aeration. However, still many test data related with those are required to clearly understand it. In this paper the aeration measurement system and calculation method are introduced. And also using this system we measured engine oil aeration fur various cases. From these results some conclusions are reduced.

The characteristics of multi-leaf feil bearing are investigated. The Foil bearing is preloaded and has several leaf foils modeled by curved beams. An analysis of the air foil bearing was performed, considering effects of foil deflection and compressible lubrication equation simultaneously. A parametric study shows that the number of foils significantly affect the static characteristics of air foil bearings and describes what the minimum film thickness means. The results include pressure profile, load capacity, dimensionless torque and minimum film thickness in the foil bearing.

The heat generated in contact type braking system can cause an unacceptable braking performance. Thermal behavior of ventilated disk brake system is presented in this paper. The temperature and velocity fields of 3-D unsteady simulated model are obtained using a software package "FLUENT". The numerical results show that there exits a temperature nonuniformity between the disk faces contacting with pads. The conduction rate through the disk and pad is calculated and the effect of material conductivity is also investigated.estigated.

Near-field recording NFR), advanced optical storage technology, relies on maintaining a small gap between the optical head and the media. This can be accomplished by utilizing the flying optical head concept as in the magnetic recording. In this research, slider/suspension system and plastic disk are tested for their head/disk interface performance. CSS tests are conducted to monitor the frictional and flying characteristics of sliders.

A cylindrical brake device with plastic deformation is designed to stop the object moving at high velocity. Baseline model is determined based on the design specification and analytic solutions. Using finite element method, effects of various design parameters, such as thickness of the cylinder, clearance between cylinder and rod, and cone angle, to the performance of the brake device are investigated. Cone-type brake device shows better performance than cylindrical brake device with constant thickness in that plastic hinges are generated sequentially from impact end to fixed boundary, thus increasing the reliability of braking operation.

Friction control is highly desirable for optimization of tribological systems. In this work, the effect of geometric structure of the solid surface on friction is investigated using a Scanning Electron Microscope equipped with a tribotester. Silicon and silicon oxide specimens were used and undulations on the surface were fabricated by mechanical and chemical methods. It is shown that the friction coefficient depends on the relative dimensions of the ball and the width of undualation. By optimizing the geometry of the undulation, friction reduction may be achieved.

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding. The temperature of polymer melts and injection pressure play a very important role in the injection molding machine. Thermal distortion and displacement of screw by temperature difference and injection pressure difference cause adhesive wear by metal-to-metal contact. In this paper we analyze thermal distortion and stress of screw includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of screw.

The design of the valve plate is most important to increase efficiency in the oil hydraulic axial piston pump. A theoretical study was carried out to clarify the pressure characteristics at the land of the valve plate in the oil hydraulic axial piston pump. Dynamic pressure acts on the land of the valve plate was computed numerically with discharge pressure, rotational speed and swash plate angle. Pressure distribution between the valve plate and the cylinder block also was obtained with dynamic pressure. The results are applicable to improve the design technique of the valve plate in the oil hydraulic axial piston pump.

The vibration characteristics of the pad fluttering in a fluid film tilting pad journal bearing(4-pad LBP) have been investigated experimentally under the different values of oil supply flow rate, bearing load and shaft speed. The vibration characteristics of the pad fluttering are estimated by measuring the time signal of circumferential distribution of the film thickness and the cascade plot of the response of the relative displacement between the bearing and the shaft. It is shown that the vibration frequency of the pad fluttering has a sub-synchronous frequency and 31mos1 does not change by the increase of shaft speed. However the vibration amplitude is increased by the increase of shaft speed. From those experimental results, pad fluttering can be thought of as a self-excited vibration. The incipient pad fluttering velocity is increased by the increase of oil supply rate and by the decrease of bearing load. It is observed that the vibration amplitude of the pad fluttering can be decreased by the control of supply oil flow rate effectively. And also It is known that the outbreak of pad fluttering does not concern with the shaft vibration.

In this paper, the dynamic characteristics of coupled herringbone groove journal bearings and spiral groove thrust bearings with conical motion were numerically analyzed, The bearing performance characteristics were calculated by the perturbation method and are solved by FDM. Stability of bearing was obtained from the threshold of instability.

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.

This paper reports on the development of the analysis program of the piston skirt system, PS-LAP. It is essential to verify the stability of the design and to improve the performance of the system. In order to do that efficiently, it is required that integrated and interactive simulation analysis program. PS-LAP is developed in the base of the object-oriented, capsulation, modulization, OLE(objected linking and embedding) and variational design theory. So it contain the expandability and flexibility of the structure. In addition to that, it is programed to make the convenient user interface by using the visualization programming. It can support the modification of the piston skirt shape, lubrication condition and so on. It is expected to reduce the money and effort for design the piston skirt system.

This study is to develop a Fe-based disc brake tinning with sponge structure for passenger car of 150km/h train and to concept design with 3 groove type for brake disc reducing hot hair-crack and certainly friction coeifficient. The developping brake linning would be to presumption of thermal stress Max.5.53k9/m0 of the 3 groove type. and It is stable friction coeifficient and wear rate on the Full Scale Brake dynamometer. So 3 groove type must be reduced to hot stress between Brake disc and Linning and Friction temperature is reduced about 20$^{\circ}C$

The importance of variable displacement piston pump is recently increasing in industrial applications, as it is widely used for raising the energy level of the fluid in hydraulic system. The regulator is the device that controls the pump output flow depending on the machine load and engine speed, and that regulates the discharge flow of the piston pump by controlling the swivel angel. This work deals with constant power control of a regulator system in bent-axis type piston pump. In order to use engine power effectively, it is important to keep the horsepower from the engine to the pump constant. Therefore, optimum power usage is obtained by accurately following the power hyperbola. First, the governing equations of the regulator are derived, and analysis is performed by numerical simulation in which significant parameters of regulator are identified. Also, we designed and manufactured the prototype of the constant power control regulator for experiments. The experimental results show the responsibility and pressure-flowrate characteristics and these are compared with the theoretical analysis. As the result, it is confirmed that the characteristics of the designed regulator correspond to the numerical simulation.

Until recently performance requirements for automatic transmission fluids have continued to change to reflect the design changes of automatic transmission. The major purpose for these design changes is to improve the fuel economy and easy driving. To meet recent performance requirements fur automatic transmission the needs for special base oils Bike API Group III and IV base oils become larger. In this paper to evaluate the effects of base oils on performance of automatic transmission fluids formulated with API Group I,II,III and IV and Dexron III and Hereon Type additive package, Brookfield viscosity, oxidation test, SAE No.2 friction test and seal compatibility test were examined. From the test we knew that the use of Croup III and IV base oils in ATF has several benefits in low temperature viscosity, oxidation stability and SAE No.2 friction characteristics.

In this study, flow factors are evaluated in terms of kurtosis using random rough surface generated numerically. As h/$\sigma$become large øx, øy, øfp approach to 1 and øs, øfs to 0 asymptotically regardless of kurtosis. øx, øy, øfp increase with increasing kurtosis in the mixed lubrication regime. øs, øfs is associated with an additional flow transport due to the combined effect of sliding and roughness. As h/$\sigma$ decreases øs, øfs increase up to a certain point, and then decrease toward zero. This behavior can be attributed to the increasing number of contacts in the mixed lubrication regime. øx in the presence of elastic deformation on the surface is larger than øx in the absence of it because local film thickness( h$\_$T/) increases by elastic deformation.

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface, the harding test was carried out under different experimental conditions in try friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing system These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

The 3 mol% yttria stabilized zirconia (3-Y PSZ) powder was heat treated at 50 0$^{\circ}C$ to evaporate the polymer binder and stabilize the tetragonal phase. The wear experiments were carried out on a ring-on-plate type reciprocating wear tester at selected temperatures with in the range room temperature to 600$^{\circ}C$ The results show that the heat treatment of powder decreases the wear rate due to the reduction of microcracks and pores in coatings and the stabilization of the tetragonal phase. Powder heat treatment enhanced the quality of the coating layer by removing remnant gases during coating process and the powder heat treatment at which tetragonal phase is stable diminished phase ratio of monoclinic. These two effects improved wear resistance characters.

Si$_3$N$_4$-6wt%Y$_2$O$_3$-lwt%Al$_2$O$_3$was prepared by hot pressed and gas pressure sintering to investigate the effect of microstructure on erosion behaviors. Hardness and fracture toughness were measured with prepared specimens to study the high temperature erosion properties. A gas blast type erosion tester was used In examine erosion behavior of the specimens up to 700$^{\circ}C$. In case of GPS silicon nitride, the erosion rate increases up to 500$^{\circ}C$ and decreases over 500$^{\circ}C$. Maximum erosion rate was observed at 300$^{\circ}C$ for HP silicon nitride. The principal factors affecting the high temperature erosive wear of brittle materials are largely dependent on high temperature properties of grain boundaries.

Tribological properties of friction materials containing different volume ratios of solid lubricants (graphite and MoS$_2$) were studied using a pad-on-disk type friction tester. Morphology and thickness of the friction film were carefully examined to correlate the friction performance with the property of the friction film. Results showed that the friction materials containing 16vo1. % of graphite and 5 vol. % of MoS$_2$exhibited best friction stability among others. In particular, the thickness of the friction film decreased as the amount of MoS$_2$increased and severe friction oscillation was observed when the friction material contained MoS$_2$only (21 vol. %). Microscopic observations and friction tests suggested that the coherent thick transfer film improved the friction stability.

Electrical and tribological behaviours of a copper-graphite brush in a slipring-brush assembly were investigated to evaluate the characteristics of electric signal transmission between a slipring and a brush. Five brush materials containing different amounts of copper and graphite were studied. The result showed that a copper-graphite brush at a particular graphite content exhibited the most stable frictional and electrical behaviour suggesting an optimum amount of a solid lubricant in a metal-graphite brush system. Microscopic observation and the surface analysis showed good agreements with this phenomena. In addition, the deviation of the friction coefficient and electric signal distortion has a close relationship with a microscopic mechanical vibration and the change of a real contact area.

Friction properties of automotive brake pads containing different types of abrasivess were investigated. Five different abrasives, including o-quartz, magnesia, magnetite, alumina, zircon, were employed in this investigation and size effects of the abrasives on friction characteristics were also studied using 1, 50, 140$\mu\textrm{m}$ size zircon. Experimental results showed that the hardness and size of these abrasive particles were strongly related to friction behaviors and wear mechanisms. Harder and smaller abrasives showed higher friction coefficient and more wear. The surfaces of friction materials with different sizes of abrasives showed that two different modes of abrasion (two-body and three-body abrasion) appeared during sliding. Considering the above results, abrasive materials were thought to destroy transfer film and the extent of the destruction depends on the types and sizes of abrasive particles. A mechanism of the wear mode transition (two-body to three body abrasive motion) was suggested considering the binding energy and friction energy in terms of abrasive particle size.

The effect of OTS(octadecyltrichlorosilane) SAM(self-assembled monolayer) on the micro-adhesion has been studied. OTS SAM was formed on the Si(100) surface and SPM (scanning probe microscope) tips with different radius of curvature were fabricated by a series of masking and etching processes. Pull-off forces of different tips on Si and OTS SAM surfaces were measured by SPM in different relative humidities. The surface of OTS SAM was changed to hydrophobic surface and the micro-adhesion force of OTS SAM was lower than that of pure Si. As the tip radius of curvature and the relative humidity increased. the micro-adhesion force increased. Based on the test results. the main parameter affected to the micro-adhesion was absorbed humidity on the surface.

Before investigating the performance of NA-Q additive oil, we have studied the properties of the commercial reference oil by using an engine dynamometer. Experimemts were conducted for 300 hours with 2,950rpm and 22kw and every 50 hours the used oil was sampled for analyzing its physical and chemical propreties. The reference oil shows stable but slightly increasing viscosities during the experiment. It has good agreements with the change of its TAN and TBN. Friction coefficients and anti-wear characteristics are compared with its ZDTP depletion factor and the diameters of wear scar. The concentrations of metal particles are analyzed with the results of ICP and spectrometer, However it is found that the concentrations by filtration method shows large difference with those by standard method in spectrometer.

Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. In this study, static and dynamic compressible isothermal lubrication problems are analyzed by the finite element method together with the Newton-Raphson iterative procedure. This analysis is introduced for prediction of the static and dynamic characteristics of air lubricated HGJB for various bearing configurations. The bearing load characteristics and dynamic characteristics are dependent on geometric parameters such as asymmetric ratio, groove depth ratio, groove width ratio and groove angle.

There are some concepts that could achieve Near-Field Recording (NPR). One of concepts is the use of the flying head with Solid Immersion Lens (SIL). The basic concept of this is almost same with that of Hard Disk Drive (HDD). This study presents the flying characteristics of the slider for NFR. Numerical simulations are performed using FEM and Broydon-Fletcher-Goldfarb-Shanno (BFGS) method. Some modifications are considered to improve flying characteristics of the slider.

Recently, fluid bearing have been studied to apply to spindle motors for hard disk drive, printer and others. Since fluid bearing have excellent stiffness and good load carrying capacity, the bearing proved to be suitable for those devices related to computer industry. In this paper, the friction and wear characteristics of the bearing were studied. The bearing appears good performance at a high temperature and high wear resistance.

This paper presents the results of the repeated sliding tests to determine the wear-life of TiN coated AISI 52100 bearing balls deposited by PVD method and to show the wear mechanisms of those. The sliding tests were carried out using a ball-on-disk tribometer under ambient conditions. The coefficient of friction, wear volume and the cycles to failures of TiN coated bearing balls were measured with different normal loads and roughness of lower specimens. On the wear-life diagram, the normal loads and the cycles to failure showed the good linear relation on log-log coordinate. With a decreasing normal load, the diagram showed that the wear-limits, at which the coated bearing balls survived more than 4000cycles were under 0.1N of the normal load.

The secondary motion of piston occurs due to the transient forces and moments in the clearances between piston skirt and cylinder liner The motions are very related to the skirt profile and the magnitude of piston-pin offset. Above all, the elastic deformation is another major effect on the piston secondary motion that has not been considered in the previous researches. In this work, the effects of elastic deformation of the piston skirt on the secondary piston motion are studied for the frictional power loss by using commercial softares, PISDYN and ANSYS.

Many computational researches have been performed about EHL film thickness in the contact between cam and follower. However, those computations do not explain the characteristics of dynamic film thickness which means squeeze film effect. Without the consideration of transient term in the Reynold's equation, the predicted film thickness has large difference from the actual film thickness. In this study, we have investigated the kinematic and dynamic simulations of rocker-arm valve train system. From the simulation, the applied load and the entraining velocity of the lubricant between cam and follower are obtained and with these values the dynamic film thickness is computed by Newton-Raphson method and compared with the steady state film thickness.

The friction and wear behaviors of Magnetron Sputtered MoS$_2$films were investigated by using a pin on disk type tester which was designed and manufactured for this experiment. The experiment was conducted by using silicon nitride (Si$_3$N$_4$) as a pin material and Magnetron Sputtered MoS$_2$on bearing steel (STB2) as a disk material, under operating conditions that include different surface roughness (Polishing specimen, Grinding specimen)(2types), linear sliding velocities in the range of 22, 44, 66mm/sec (3types), normal loads vary from 9.8N, 19.6N, 29.4N(3types), corresponding to contact pressures of 1.9∼2.7GPa and atmospheric conditions of high vacuum( 1.3${\times}$10$\^$-4/Pa), medium vacuum( 1.3${\times}$10$\^$-l/Pa), ambient air(10$\^$5/Pa)(3types). We investigated fracture mechanism in magnetron sputtered MoS$_2$films with Magnetron Sputtering method in each experiment.

This paper presents the knowledge and information construction trends in the oil industry. The investigated results show that the website construction and e-business level in oil industries including oil circulation distributors are very low and introduction stage compared with those of other industries.