• Tribology and Lubricants
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• v.12 no.3
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• pp.39-47
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• 1996

The magnetic fibrous polymeric oil filter elements for industrial lub-systems were obtained by pneumoextrusion processing prepared from thermoplastic pqlymer (polyamide) containing a magnetic particulate filler (Ba ferrite), and treated subsequently in a magnetic fields. Using the standard laboratory oil filtration test rig, metallic particle quantifier and image analyser system, the dependence of filtration charateristics of the magnetic filter media on the parameters of porosity and magnetic properties was investigated. The pressure drops and efficiencies of lubricating filter elements were measured on the packing density and magnetised filler content of filter element. Also, the industrial lub-systems such as lubricant filters for gear test rig and electric discharge processing machine were used for testing the flitrational characteristics of tl, c magnetised filter elements. The magnetic fibrous polymeric filter material was shown to possess a highly filtration efficiency in filtering the fine ferrous particles with increasing the magnetic force of filter element. Therefore, it is expected that the magnetic fibrous polymeric filter material should be used for effective oil filrers on the industrial lub-systems.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.1
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• pp.3-9
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• 2009

Recently, a high speed cutting is essential requirement to satisfy latest demand of high precision product and machining of hard materials. However heat generation by high speed rotation causes many problems. The machining error and shortening spindle lifetime by thermal stress is typical example. Generation of heat is mostly caused by sliding at the rotor and bearing. For minimization of heat generation at bearing, decision of the condition of proper lubrication is necessary. The thermal study about 40,000rpm spindle by changing the condition of oil-air lubrication method is carried out in this paper. The results of this paper can be used effectively in the decision of oil-air lubrication condition of other types of spindle for machine tools.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.326-333
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• 2004

This paper presents the structural characteristics analysis of a high-speed horizontal machining center with spindle speed of 50, 000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motor and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guide. The structural analysis model of the high-speed horizontal machining center is constructed by the finite element method, and the validity of structural design is estimated based on the structural deformation of the high-speed horizontal machining center and spindle nose caused by the gravity and inertia forces.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.69-75
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• 2004

This paper presents the thermal characteristics analysis of a high-speed motor-separated spindle system consisted of angular contact ball bearings and built-in motor with oil-jet lubrication. The spindle system is composed of the main spindle and sub-spindle which are mechanically connected by a flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front and rear bearings of the sub-spindle. The thermal analysis model of spindle system is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on temperature distribution and heat flow under the various testing conditions related to material of bearing ball, spindle speed and coolant temperature.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.151-158
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• 2001

This paper presents a method for evaluating the lubrication characteristics between the plunger and cylinder in a radial type plunger pump. A numerical analysis is carried out in order to obtain the pressure distribution and acting forces between the plunger and cylinder. The pressure distribution is also measured experimentally by using pressure transducer through the cam type test machine. The experimental pressure distribution result is compared with the numerical result which is estimated by the computer simulation. In conclusion, the acting forces to the plunger are expressed for the operating conditions such as clearance, supply pressure, rotation speed and viscosity of oil.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.1
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• pp.64-73
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• 2011

Oil price prediction is an important issue for the regulators of the government and the related industries. When employing the time series techniques for prediction, however, it becomes difficult and challenging since the behavior of the series of oil prices is dominated by quantitatively unexplained irregular external factors, e.g., supply- or demand-side shocks, political conflicts specific to events in the Middle East, and direct or indirect influences from other global economical indices, etc. Identifying and quantifying the relationship between oil price and those external factors may provide more relevant prediction than attempting to unclose the underlying structure of the series itself. Technically, this implies the prediction is to be based on the vectoral data on the degrees of the relationship rather than the series data. This paper proposes a novel method for time series prediction of using Semi-Supervised Learning that was originally designed only for the vector types of data. First, several time series of oil prices and other economical indices are transformed into the multiple dimensional vectors by the various types of technical indicators and the diverse combination of the indicator-specific hyper-parameters. Then, to avoid the curse of dimensionality and redundancy among the dimensions, the wellknown feature extraction techniques, PCA and NLPCA, are employed. With the extracted features, a timepointspecific similarity matrix of oil prices and other economical indices is built and finally, Semi-Supervised Learning generates one-timepoint-ahead prediction. The series of crude oil prices of West Texas Intermediate (WTI) was used to verify the proposed method, and the experiments showed promising results : 0.86 of the average AUC.

• Tribology and Lubricants
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• v.39 no.4
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• pp.133-138
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• 2023

This paper presents a discussion on lubricating oil filters. The maintenance of lubricating oil filters can improve the performance of mechanical systems and extend the service life of the lubricating oil. Therefore, the effective management of the lubricating oil can extend the service life of the machine and reduce maintenance costs. A representative method for managing lubricating oil is filtering the lubricating oil using a lubricant filter. However, effectively managing a lubricating oil using a lubricant filter requires an understanding of the related knowledge. In this paper, we present the definition, classification, characteristics, specifications, performance, and self-cleaning function of lubricating oil filters. The lubricant filters are classified based on the filter material, filtering method, filtering location, and amount of filtered fluid. Cellulose and glass fiber materials are conventionally used as materials for lubricant filters, and recently, metal materials, which show excellent durability, are being increasingly adopted. The filtering methods can be classified into physical, chemical, magnetic, and electric field methods, and the lubricant filters can be classified according to their location in the lubrication system. The beta ratio and efficiency of the lubricant filter can be determined based on the performance of the filter. Finally, there are many products or technologies that add a self-cleaning function to the filter to remove foreign substances or contaminants for efficient management.

• Tribology and Lubricants
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• v.6 no.1
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• pp.57-67
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• 1990

For increasing the performance of Machine tools, the improvement of the static and dynamic characteristics of spindle bearing is important. In this paper are the static characteristics, the pressure distribution, friction force and outlet flow rate, and the dynamic characteristics stiffness and damping coefficient, of a cylindrical hydrostatic journal bearing with multi oil pockets are analyzed.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.137-144
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• 2000

In order to achieve systematical method for improving motion accuracy of hydrostatic table, an algorithm using finite element method is proposed in this paper. Quantification of averaging effect of oil film on motion error is performed theoretically by analysis on the relationship between spacial frequency of rail form error and motion error of table. Influences of film stiffness and pocket size on the motion error of table are also analyzed theoretically. Validity of the algorithm is verified experimentally from the test on the motion error of table with three types of rail which have different form profile. Experimental results show that the algorithm is very effective to analyze theoretically the motion error of hydrostatic table.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.105-111
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• 2012

High speed machining is the core technology that influences the performance of machine tools, and the high speed motor spindle is widely used for the high speed machine tools. The important problem in high speed spindle is to minimize the thermal effect by motor and bearing and frequency effect. This paper presents the thermal characteristic analysis and frequency experiment for a high speed spindle considering the flow rate of cooling oil. A high speed spindle is composed of angular contact ceramic ball bearings, high speed built-in motor, oil cooling jacket and so on. The thermal analyses of high speed spindle need to minimize the thermal effect and maximize the cooling effect and they are carried out under the various cooling conditions. Heat generations of the bearing and the high speed motor are estimated from the theoretical and experimental data. To find out the characteristic of vibration, the high speed spindle is excited in operational range. This result can be applied to the design and manufacture of a high speed tapping spindle.