• Tribology and Lubricants
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• v.24 no.1
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• pp.1-6
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• 2008

An experimental study was conducted to evaluate the viscosity characteristics of multi-grade engine oils in which contain diesel fuels. Unused engine oils of SAE 5W40, 10W40 and 15W40 were blended with a diesel fuel ratio of 5%, 10%, and 15%. The viscosity of a diluted engine oil was measured with temperature variation ranging from $-20^{\circ}C$ to $120^{\circ}C$ using a rotary viscometer. The diluted engine oil in which is blended to a diesel fuel plays an important role for decreasing an engine oil viscosity, which may decrease the oil film thickness and a load-carrying capacity. Test results show that the viscosity tends to fall for the increased temperature when engine oil is mixed with a diesel fuel. Especially, the viscosity at a low temperature zone is radically decreased compared with a high temperature zone. Based on the experimental results, the empirical equation that can predict the viscosity of diluted engine oil is expressed in the exponential function with the variation of the temperature and a fuel ratio of diluted engine oil. This equation may be possible to predict the limitation of the oil-fuel dilution rate at the concept design stage of the CDPF system, which doesn't affect the influence of the tribological components.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.96-99
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• 2003

In this paper, ageing diagnostics in the large capacity oil transformer are investigated. Following items are investigated for the ageing diagnostic in transformer oils (leakage current of sensor, power consumption and temperature of transformer oil). All temperature data are gathered from daily report in the substation. The power consumption of transformer are gathered output report of APIS(Airport Power Information System). Especially, data of sensor leakage current are accumulated from the online diagnostic system for transformer oil. The temperature of transformer oils major change factor was ambient temperature and capacity of power load. The leakage current are change by oil temperature. The leakage current ware not more than 2 [nA] in summer,

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.86.6-86
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• 2001

For discriminating between water and oil, a novel method is proposed in this paper. As a fundamental result, the temperature dependence of ultrasonic travel time of water and oil measured from 5$^{\circ}C$ to 40$^{\circ}C$ at a step of 5$^{\circ}C$ is found as that the ultrasonic travel time of oil increases with increasing temperature, whereas that of water decreases. The proposed method for discriminating between water and oil is based on the opposite temperature dependence of ultrasonic travel time of water and oil. Besides the advantages of non-invasion and on-line measurement, there are no requirements of measuring the temperature of liquid being detected and obtaining previously a large quantity of database, and furthermore, only two times of measurements are ...

• Journal of the Society of Disaster Information
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• v.18 no.2
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• pp.324-332
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• 2022

Purpose: In order to conduct a spontaneous ignition test in which a fire occurs in the absence of an ignition source due to the oil adsorbed on the towel. A phenomenon in which spontaneous ignition occurs when adsorbed to fibers using flaxseed oil, which is drying oil and olive oil, which is non-drying oil, is tested through an experiment. Method: After placing the sample container in the experimental device, observe the change in the central temperature of the sample, and when the central temperature rises above the set temperature and a fire occurs, it is judged as "ignition", and the experiment is stopped after checking the maximum value of the central temperature of the sample,When the central temperature of the sample was maintained similar to the set temperature, it was judged as "non-ignition" and the experiment was stopped. Result: In the towels with adsorbed flaxseed oil, the temperature in the sample container increased rapidly and combustion occurred in sheets 5, 10, and 15. Olive oil is a non-drying oil, does not ignite because it is difficult to dry because carbon is a single bond and it is difficult to bond with oxygen. Conclusion: It was confirmed that the more the amount of towel adsorbed to the drying oil, flaxseed oil, the longer the time to reach the set temperature and the occurrence of ignition.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.2
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• pp.78-83
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• 2007

An experimental study has been carried out to analyze the thermal stability and to estimate the lifetime of refrigerating lubricants. PAG and POE oil are considered as test oils in this study. The viscosity of PAG and POE oil was measured by the vibration type viscometer while temperature is varied periodically in the range of $0^{\circ}C{\sim}100^{\circ}C$. In order to estimate lifetime of PAG and POE oil with temperature, the viscosity was measured while the test temperature of oils was maintained continuously at $180,\;200\;and\;220^{\circ}C$. The lifetime of oils is estimated as the decrease in viscosity change by 15%. The results indicate that the reduction rates of viscosity of PAG and POE oil are less than 5% after 510 temperature variation cycles. However, when the oils are kept at high temperature, it is found that the lifetimes of PAG oil is seen to be 244, 177 and 89 hours at the test temperature of $180,\;200\;and\;220^{\circ}C$, respectively, where as the lifetimes of POE oil are estimated to be 1,744, 1,007 and 334 hours at the temperature of $180,\;200\;and\;220^{\circ}C$, respectively. Thus, the lifetime of POE oil is found to be much longer than that of PAG oil. The lifetime correlations of PAG and POE oil are also obtained by Arrhenius's equation method in this paper.

• Journal of the Korean Society of Tobacco Science
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• v.24 no.2
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• pp.101-106
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• 2002

This study was conducted to investigate the pyrolysis products of patchouli oil by Curie-Point pyrolysis. The pyrolysis of patchouli oil was performed at the temperature of 16$0^{\circ}C$, 42$0^{\circ}C$, $650^{\circ}C$, 76$0^{\circ}C$, and 92$0^{\circ}C$ by Curie-Point Pyrolyzer. The pyrolysis products were analyzed by gas chromatography(GC) and mass selective detector(MSD). Total 21 components were identified in the pyrolyzates of patchouli oil. The temperature for maximum formation of most of these compounds was in the range of 76$0^{\circ}C$~92$0^{\circ}C$. The major components were $\beta$-patchoulene, $\alpha$-guaiene, $\beta$-caryophyllene, $\alpha$-patchoulene, seychellene, $\delta$-guaiene, and patchouli alcohol. The numbers of the pyrolyzed products of patchouli oil were increased by increasing temperature, however, the yields of major components such as patchoulene, guaiene, seychellene and patchouli alcohol decreased as the temperature of pyrolysis was raised to 92$0^{\circ}C$, the highest temperature in this experiment. The optimum temperature for formation of the pyrolysis products such as styrene, indane and naphthalene was at 92$0^{\circ}C$.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.244-247
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• 2008

The phenomena of oil whip in steam turbine takes place for the un-balancing force between rotor shaft and bearing oil film. The several parameters that affect onset of oil whip have been well known. However, the major parameter of oil whip is shaft mis-alinement. A oil whip causes the high vibration and the shutdown of rotor system. We mostly stop the steam turbine to adjust a shaft re-alinement concerning oil whip. In this case, It needs many costs for maintenance and long shutdown times. In this study, we study and observe the oil whip of the 300MW steam turbine in many years and we conduct the field test for another steam turbine for reducing vibration from oil whip. The results of this study are that a oil whip takes place with a particular rotating speed or a particular turbine output and the oil temperature change is a very effective method for on-line oil whip treatment.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.386-391
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• 2005

An experimental study was conducted to analyze the thermal stability and to estimate the lifetime of refrigerating lubricants. PAG and POE oil are considered as a test fluids in this study. The viscosity of PAG and POE oil was measured by the vibration type viscometer while temperature is varied periodically in the range of $0^{\circ}C{\sim}100^{\circ}C$. The results indicate that the reduction rates of viscosity of PAG and POE oil were less than 5% after 510 cycles. In order to estimate lifetime of PAG and POE oil with temperature, the viscosity was measured while the temperature of oils was maintained at 180, 200 and $220^{\circ}C$. It is found that the lifetimes of PAG oil were shown to be 244, 177 and 89 hours at the temperature of 180, 200 and $220^{\circ}C$, respectively. Also the lifetimes of POE oil were estimated to be 1,744, 1,007 and 334 hours at the temperature of 180, 200 and $220^{\circ}C$, respectively. The lifetime correlations of PAG and POE oil are suggested in this paper.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.87-94
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• 2004

Recently, technical trend in machine tools is focused on enhancing of speed, accuracy and reliability. The high speed usually results in thermal displacement and structural deformation. To minimize the thermal effect, precision machine tools adopt a high precision cooling system. This study proposes a temperature control for an oil cooler system using Pill control with fuzzy logic. In the cooler system, refrigerant flow rate is controlled by rotational speed of a compressor, and outlet oil temperature is selected as the control variable. The fuzzy control rules iteratively correct PID parameters to minimize the error and difference between the outlet temperature and the reference temperature. Here, ambient temperature is used as the reference one. To show the effectiveness of the proposed method, a series of experiments are conducted for an oil cooler system of machine tools, and the results are compared with the ones of a conventional Pill control. The experimental results show that the proposed method has advantages of faster response and smaller overshoot.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.280-285
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• 2024

In this paper, the electrical properties of liquid insulating oil were analyzed by changing the ambient temperature change at 10℃ in-tervals from 0℃ to 30℃ through an insulation breakdown experiment in order to analyze the insulation performance of liquid in-sulating oil that varies according to temperature changes. As a result, it was confirmed through experiments that the lower the am-bient temperature, the higher the insulation breakdown voltage, depending on both the electrode shape and the electrode interval, and it was determined that the lower the ambient temperature, the higher the insulation performance of the liquid insulating oil.