• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.77-82
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• 2010

This study has conducted numerical analysis for lubrication system of transmission for commercial vehicle. The lubrication oil system in transmission can be applied to a large scale commercial vehicle which is over 15tons. The flow rate of lubricating oil has been obtained for each of branch port from the lubrication pipe. The results from numerical simulation are mainly suggested for the mass flow rate of lubrication oil in the rotating main shaft of transmission system. It has been found that the mass flow rate from oil hole increased with an rotating rate of main shaft. The flow characteristic from oil hole has been presented for the lubricating system in the manual transmission.

• Tribology and Lubricants
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• v.21 no.5
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• pp.227-235
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• 2005

This paper presents a tribological study on the failure cases of automatic transmission components in a passenger car. The automatic transmission system is composed of torque converter, clutch, brake, planetary gear, and valve body controlling oil pressure of an automatic transmission fluid. The most largest influence components in an automatic transmission are a torque converter and clutch plate in which are influenced by a wear and torque converting energy loss. The failure case study of an automatic transmission indicates that the tribological design and maintenance technologies should be considered as a key design concept. This means that the failure and power energy loss come from the friction, wear and a oil leakage of an automatic transmission, which is related to the oil seal and O-ring seal failures.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.185-190
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• 2003

Synchronizer ring performance is strictly required in order to extend manual transmission oil drain interval. Zn type additive, which is used as dispersant and anti-wear additive instead of SP additives in manual transmission oil, is applied to improve Synchronizing function and durability. But only Zn type additive is not suitable for high torque transmission because it has not good extreme pressure characteristics. We research on the synchronizer friction and extreme pressure properties in according to change additive types. As a result, it was found that the use of non-active extreme pressure and friction modifier additives has benefit in the improvement of synchronizer friction characteristics and durability.

• Applied Microscopy
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• v.50
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• pp.21.1-21.3
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• 2020

Sample preparation is significantly important to the high-resolution transmission electron microscopy (HRTEM) characterization of nanomaterials. However, many general organic solvents can dissolve the necessary organic polymer support layer in TEM grid, which causes it difficult to obtain high-quality samples of oil-soluble nanomaterials. In this study, a new sample preparation method for oil-soluble nanomaterials has been developed by using the sublimable material as a transition layer. Experiments also show that there is no damage to TEM grids and high-quality HRTEM images can be obtained via this method. This approach paves the way to applicable HRTEM sample preparation of oil-soluble nanomaterials.

• Environmental and Resource Economics Review
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• v.22 no.4
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• pp.671-689
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• 2013

Transmission mechanisms of volatility between two crude oil markets (WTI and Brent markets) have drawn the attention of numerous academics and practitioners because they both play crucial roles in portfolio and risk management in crude oil markets. In this context, we examined the volatility linkages between two representative crude oil markets using a VECM and an asymmetric bivariate GARCH model. First, looking at the return transmission through the VECM test, we found a long-run equilibrium and bidirectional relationship between two crude oil markets. However, the estimation results of the GARCH-BEKK model suggest that there is unidirectional volatility spillover from the WTI market to the Brent market, implying that the WTI market tends to exert influence over the Brent market and not vice versa. Regarding asymmetric volatility transmission, we also found that bad news volatility in the WTI market increases the volatility of the Brent market. Thus, WTI information is transmitted into the Brent market, indicating that the prices of the WTI market seem to lead the prices of the Brent market.

• Tribology and Lubricants
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• v.17 no.1
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• pp.16-21
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• 2001

The wear particles is released from the moving surfaces in gear systems of transmission and its morphology is directly related to the damage and failure to gear system from which the particles originated. It is the effective method for damage condition estimation of automobile transmission gear to observe wear debris in gear oil. We tested with new transmission and took out gear oil according to driving distance. To be applied to damage condition of gear system in transmission of automobile,4 shape parameters of wear particles in gear oil were calculated and wear volume were presumed with the image processing system.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.235-240
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• 2003

Auto transmission system is composed by torque converter. clutch, brake, planetary goat and valve body controlling oil pressure. In the automatic transmission, the most largest influence elements are torque converter and clutch for oil performance. In this piper I studied failure of tribology causing sealing poor of the acting parts, leakage of the oil pressure and poor of the lubrication.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.272-278
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• 1999

It is the effective method to diagnosis damage process of gear system such as automobile transmission to observe wear particle in gear oil. We tested with new transmission and took out gear oil according to drive distance. 4 shape parameters of wear particles in gear oil were calculated and wear volume were presumed with the image processing system. To be applied to damage diagnosis of gear system in transmission of automobile, we discuss number of wear particles, shape characteristics and total wear volume according to driving distance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.40-46
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• 2012

In this study, numerical analysis was conducted to understand the flow characteristics of lubrication system in a manual transmission installed in a commercial vehicle. Also, the analysis was conducted with the purpose of improving the heat and lubricative condition of the transmission. Discharging flow rates on each oil hole outlet according to various engine rotating speed and the length of oil hole branch was calculated. In conclusion, as engine rotating speed is high and the length of oil hole branch is long, the discharging flow rate is high by virtue of the centrifugal force. In addition, this study proposed data for optimal design of lubrication system in manual transmission for a commercial vehicle.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1512-1519
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• 2013

Oil-impregnated paper is a major type of insulation used in oil-filled converter transformers for both traditional and new energy systems. This paper presents and analyzes the results of the experiment conducted on the electrical aging of oil-impregnated paper under AC-DC combined voltages using the pulsed electro-acoustic (PEA) technique. The formation and dynamics of space charge affected the performance of insulation material. The electrical aged oil-paper insulation was obtained through electrical aged experiments under the voltages. Based on the PEA technique, measurements were carried out when the oil-paper insulation system was subjected to different stressing and aging times. The space charge dynamics in the bulk of the oil-paper insulation system with different aging times were measured and analyzed. Characteristic parameters such as the total charge injection amount, the total charges of fast moving and slow moving, and the distortion factor of electric field were calculated and discussed. Results show that the longer electrical aging time, the more charges trapped in the bulk of aging sample. It leads to larger distortion factor of electric field in the bulk of aging samples and accelerate degradation of oil-paper insulation under AC-DC combined voltages.