• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.176-180
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• 1997

Evaluating an optimum seal design to minimize leakage is concerned in the aspect of flow control. Flow is characterized into five categories according to its leakage path. Effect of geometry and leakage path are evaluated according to variation of sealing geometry. To simulate an oil jet or oil mist type high speed spindle lubrication, the working fluid is regarded as two phases that are mixed flow of oil phase and air phase. Both of the turbulence and the compressible flow model were introduced in CFD(Computational Fluid Dynamics) analysis. This offers a methodological way of enhancement seal design for high speed spindle.

• Tribology and Lubricants
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• v.26 no.1
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• pp.61-67
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• 2010

The purpose of this paper is to study and analyze the failure examples on tribological characteristics of an automotive steering system. In this failure study, the grease leakage may stick leaked grease, dust, and wear particles between pinion and rack gears in mechanical steering system. In the case of seal failures such as a rod seal, o-ring and oil seals, the gear box and oil pump do not operate properly due to lack of oils. This means that oil pump does not supply a working fluid and produce a normal oil pressure of the steering system. This leads to leak a working fluid from the seals and produce a wear between pinion and rack gears. Especially, the leaked oil is usually mixed with internal wear particles and foreign dust/fine sands. Thus no leakage of working oils is very important design concepts, which is strongly related to the sealing components and smoothly operating of the mechanical friction parts of power steering system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.613-617
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• 2001

The test items like as endurance, air leakage and oil endurance test is requested for reliability evaluation about O-ring which is a kind of core machinery accessories of semi-conduct manufacturing equipment. For verification of these, we design and manufactured a test system for endurance, air leakage and oil endurance of O-ring for semi-conduct manufacturing equipment, and also performed the test for two kinds of O-ring, as it were Viton and Kalretz. The characteristics of this test equipment consist in realization of the test conditions of semi-conduct manufacturing equipment and satisfying the test method. The test conditions are cut gas, vacuum grade, temperature and revolution numbers in the endurance test system, vacuum grade and temperature in the air leakage test system, temperature and time in the oil endurance test system. The separating test results for wearing which is an oil endurance test item, the wearing index of domestic produced Viton O-ring is higher than foreign product by 2%, wearing rate of Kalretz O-ring better than Viton O-ring by 17%, and particles existed in various place. The test result of air leakage which is measured through the RGA sensor used Helium, the vacuum grade was $10^-3$Torr. And the test result of oil endurance, the volume change rate was 7~15%. Hereafter, we intend to analysis the reliability test evaluation and to utilize for domestic manufacturing companies by establishing data base and developing reliability softwares.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.7-11
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• 2008

This paper presents the experimental results on the oil leakage characteristics of stem seals depending on the driving distance in LPG vehicle. The increased speeds of the camshaft and oil temperatures do not affect to the oil leakage of the seals because of the low level of driving distances less than 40,000 km. But the increased driving distance over 50,000 km to 100,000 km shows a rapid deteriorating the sealing performance, which may increase the oil leakage through the rubbing surfaces between the poppet valves and stem seals. In this result, the stem seal may be exchanged about the driving distance of 50,000 km to 60,000 km with a currently used stem seal in LPG car. Thus, the stem seal for a poppet valve should be resigned for the increased durability and long life.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.51-59
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• 2021

In this study, the purpose of this study was to quantitatively grasp the specific correlation between the raw material and the occurrence of leakage by analyzing the characteristics of leakage by adjusting the type and content of the raw material constituting the asphalt mastic coating waterproofing material. To this end, two raw materials, CA (calcium carbonate) and ASE (anti-sedimentation), which are organic and mineral extender for asphalt mastic waterproofing membrane coating, were selected. viscosity and oil leakage stability (20 ℃, 40 ℃) was evaluated. As a result of the evaluation, the oil leakage stability and viscosity were inversely proportional to the CA average particle size, and it was quantitatively proven that a correlation in proportion to the ASE content was established. The results of this study are expected to be used as core data for basic mixing design in the future mixing studies to improve leakage of asphalt mastic waterproofing membrane coating.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.337-345
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• 2018

In this study, observations of oil leakage samples taken from the actual site were performed to identify the causes of the oil leakage phenomenon. As a result, the separation of the material components was determined as the main cause of the oil leakage phenomenon based on the changes in the surface conditions, and verification of this was conducted. The evaluation results confirmed that the filler component of the asphalt mastic subsided with the lapse of the settling time, and that the difference ratio of the filler contents of the upper and lower specimens was up to 23.8% after day 28. Based on these results, a hypothesis on the oil leakage mechanism of asphalt mastic was established, and then modeling of the entire process of oil leakage was performed.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.31-39
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• 1997

Between 40,000 and 60,000 liters of light oil were spilled when an underground pipe broke at a newly constructed landfill site in coastal area, Korea. Methods were presented to examine the subsurface distribution of the contaminants in hydrocarbon-contaminated soil. As results, large quantities of oil and grease were found to have migrated horizontally at the site. Oil and grease plume at concentrations of 38-88 mg/kg was formed horizontally through silty sand with gravel fill and the vertical movement of the contaminants was thought to be limited to groundwater level between 2 and 4 m corresponding to sea water level. Right after finding the leakage area, the early action of excavation and pumping out the mixture of groundwater and oil was taken and it was proved to be very effective for preventing further contamination. Two months after the leakage, oil and grease in sea water sample near contaminated area was not detectable.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.610-614
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• 1996

Sealing of lubricat-air mixture in the high performance machining conte is one of most the important characteristics to carry out enhanced lubrication. High speed spindle requires non-contact type of sealing mechanism. Evaluating an optimum seal design to minimize leakage is concerned in the aspect of flow control. Effect of geometry and leakage path are evaluated according to variation of sealing geometry, Velocity, pressure, turbulence intensity of profile is calculated to fina more efficient geometry and variables. This offers a methodological way of enhancement seal design for high speed spindle. The working fluid is regarded as two phases that are mixed flow of oil phase and air phase. It is more reasonable to simulate an oil jet or oil mist type high speed spindle lubrication. Turbulence and compressible flow model are used to evaluate a flow characteristic, This paper arranges a geometry of mostly used non-contact type seal and analyzes leakage characteristics to minimize a leakage on the same sealing area.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.91-95
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• 2004

Utilization of underground construction if increased by the large size ＆ skycraperlization of building recently. Therefore. waterproof dependence of underground construction is risen. However, water leakage was happened by rupture by concrete conduct, drying shrinkage. form tie. In underground environment soil class, degradation of waterproofing is showing to corrode by oil. An odious smell by oil, promotion evil of reinforcing rod corrosion, declination of durability can happen. Then, practical un degree of underground spare becomes low, Because oil or water permeates by construction by degradation to waterproof class corrode by oil, is considered to affect evil durability of construction.

• KSTLE International Journal
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• v.3 no.2
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• pp.79-83
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• 2002

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindle requires non-contact type of sealing mechanism. Current work emphases on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet was injected against through the leakage flow, It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement The sealing effects of the leakage clearance and the air jet magnitude are studied in various parameters. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient Effect of sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.