• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
• /
• pp.353-354
• /
• 2002

This study represents the newly advanced formulation of hydraulic fluids for extended drain interval and introduces the performance results of used oil samples from various excavators. The used oil samples, in this paper, show that there is a sharp change in viscosity drop and moderate additive depletion. For the extension of hydraulic fluid life. it is necessary to improve the stability of viscosity and oxidation. New target properties from the used oil analysis were proposed for extended life. Hydraulic oil with the viscosity index of 140 and improved thermal stability consists of group III base oil, showed the possibility of extension of fluid life.

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

• Tribology and Lubricants
• /
• 제27권4호
• /
• pp.209-212
• /
• 2011

The capacitive application(prove) can be used to measure the complex permittivity of dielectric material of various thickness and cross section. This paper presents that we designed the analysis system of engine oil permittivity to know the relation between the engine oil deterioration and the prove dimension. Each of the dimension of capacitive prove is changed and then electric capacity is measured by LCR {Inductance(L), Capacitance (C), and Resistance (R)} meter. The engine oil permittivity has extracted in the prove measurement. As the additional research, this paper suggest the best of the prove dimension for the permittivity measurement.

• Tribology and Lubricants
• /
• 제22권2호
• /
• pp.99-104
• /
• 2006

The dielectric constants of fresh engine oils were obtained according to various types of oil, temperatures and frequencies. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constant of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated by cross capacitances measured by a sensor tube. Before finding the correlation, as a prerequisites study, the best condition measuring the dielectric constant was found. In general, it was found that the value of dielectric constant became stable below $60^{\circ}C$ regardless frequency variation. Further, above 6kHz, the dielectric constant became stable even if temperature had been above $100^{\circ}C$.

• Tribology and Lubricants
• /
• 제26권1호
• /
• pp.73-77
• /
• 2010

One of the important trends for condition monitoring in the 21st century is the development of smart sensors that will permit the cost-effective continuous monitoring of key machine equipments. In this study, an integrated in-line oil monitoring sensor assigned for continuous in situ monitoring multiple parameters of oil performance is presented. The sensor estimates oil deterioration based on the information about chemical degradation, total contamination, water content of oil and oil temperature. The oil oxidation is estimated by "chromatic ratio", total contamination is measured by the changes in optical density of oil in three optical wave-bands ('Red', 'Green' and 'Blue') and water content is evaluated as relative saturation of oil by water. In order to evaluate the sensor's effectiveness, the sensor was applied to several used oil samples in steel making industry and the results were compared with those measured by standard test methods.

• Tribology and Lubricants
• /
• 제19권5호
• /
• pp.251-258
• /
• 2003

New method and device for the on-line measurement of soot concentration in a diesel engine oil are proposed, where the measurement principle is based mainly on attenuated internal total reflection. The detector were evaluated in various ranges of contaminated oils by carbon black particles. It was found that the proposed detector could be well used to monitor the oil deterioration due to soot contamination. Operational range of the detector was found from 0 to 5 mass percentage of soot content. Test results with water and fuel dilution showed that these effects were not remarkable. However, adsorption of carbon black particles onto the measurement surface was considered to be a critical problem of the detector. Effects of particle deposition on the interface was experimentally evaluated with the oil temperature and flow turbulence and discussed throughout this work.

• 드라이브 ㆍ 컨트롤
• /
• 제19권1호
• /
• pp.26-33
• /
• 2022

This study dealt with a self-propelled spinach harvester, which is capable of carrying out sequential harvesting work. This study aimed to find the cause of the harvester's occasional performance deterioration, which occurs in the process of simplifying the hydraulic circuit, using a multi-domain analysis model. The study was carried out in the following manner. First, a hydraulic system analysis model, which combines linear motion, rotary motion, hydrodynamic behavior, and an electrical signal, was developed through SimulationX software, specialized in multi-domain analysis. Second, a scenario for single behavior and coupled behavior was set out on an actuator basis. Third, the flow rate of the hydraulic system, which is not required for the movement of the actuator, was quantitatively analyzed. The results showed that a change in oil temperature was the cause of the harvester's occasional performance deterioration. And the higher the oil temperature, the more serious the performance deterioration, especially as the number of actuators operated simultaneously was small.

• Tribology and Lubricants
• /
• 제11권3호
• /
• pp.40-47
• /
• 1995

The engine oil life was examined experimentally for small size single cylinder engines. This study was conducted in the laboratory. An Eddy Current type engine dynamometer was used with a motorcycle and a cultivator engine. Physical and chemical properties of used oil was analyzed to examine the oil life. Flushed oil was used for the reference instead of the new oil. It were found that deterioration of dynamic viscosity and anti-wear property of engine oil was due to dilution by fuel not depletion of ZDTP.

• 한국인쇄학회지
• /
• 제29권3호
• /
• pp.41-53
• /
• 2011

For manufacturing the tape for repairing archival documents, we tested ten carrier candidates for selecting best material. The tensile strength, transmissivity, stability of deterioration, and processability were determined. Physical-chemical characteristics and stability of deterioration was best to the Hanji. Tensile strength and transmissivity was best in tracing paper, but was low in oil paper, white sketch paper, lyon coat paper. Synthetic carrier to tensile strength showed higher than paper carrier and to the transmissivity showed 2-8 times higher than paper carriers. The tracing paper to the transmissivity was 10 times higher than others. To determine characteristic of conservation to the selected carriers, stability of deterioration was examined at conditions of $90^{\circ}C$ for 15 days. Oil paper and white sketch paper turned strongly yellowish. Cellulopane, Felt, and Cpp film showed stable stability of deterioration, but deformation like wrinkles. PET film and Syntheletic film showed excellent conservation characteristics without any change of exterior. Test of adhesive uniform between carriers and adhesive processability was performed. PET film > Syntheletic film > Tracing Paper in order were determined. Ununiformal adhesive characteristics appeared to Hangi. Accordingly, we thought that Hanji as carrier material might be unsuitable because of low adhesive processability.

• 전기학회논문지
• /
• 제63권2호
• /
• pp.297-305
• /
• 2014

Nowadays new water supply projects have been on the decline as the water-power constructions have saturated, which means that the existing power equipment have slowly aged and they require more efforts to maintain the system performance. An effective asset management method of power equipment has become a great necessity from both economical and technical aspects. To be balanced, the asset management should look into all three parts: management, engineering, and information. The purpose of this paper is to study a Risk-Based Maintenance (RBM) matrix method through the deterioration evaluation algorithm for an efficient reliability assessment of oil-immersed power transformers by considering both asset management and technical evaluation. Make use of this result, the equipment will be decided to be replace or repair otherwise on service.