• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.99-100
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• 2002

Radial, tilting-pad proceeding bearings are applied in high speed rotating machines operating at stable small and mean loads and the peripheral speeds of proceeding reaching 150 m/s. The operation of bearing can be determined by static characteristics including the oil film pressure, temperature and viscosity distributions, minimum oil film thickness, load capacity, power loss, oil flow. The operation of 5-lobe tilted-pad proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions habe received by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss. oil flow, maximum oil film pressure, maximum temperature were computed for different sets of bearing geometric parameters as: bearing length to diameter ratio, pad angular length and width as well as pad relative clearance.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.387-392
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• 2008

In order to improve the efficiency of the main transformer in a tilting train, the optimal operation of a cooling system is necessary. For the development of the optimal control algorithm of a cooling system, the mathematical model of a main transformer cooling system was developed. This includes the dynamic model of a main transformer, an oil pump, an oil cooler and a blower. The system algorithm of a cooling system, which consists of the temperature setpoint algorithm and the temperature control algorithm, was developed. Optimal oil temperatures of the inlet and the outlet of the main transformer were obtained by considering the total electric power consumption of the system. The oil inlet temperature was controlled by the blower and the oil outlet temperature was controlled by the oil pump. A simulation program was developed by using the mathematical model and the system algorithm. Simulation results showed that the system algorithm developed from this study may be effectively used to control the main transformer cooling system in a tilting train.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2017-2022
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• 2008

The crude oil pump system is the equipment for transporting crude oil and it consists of 3 major components, a motor and an impeller which discharge underground crude oil, a pipestack that transmits the cooling oil and power, and a cooling oil unit & junction box that provides cooling oil and electric power. When considering the system characteristics that it has to be installed at a depth of deeper than 100 m, a design technology for the efficient control of the heat occurring at a conductor and motor is necessary and it is the essential factor for ensuring system durability. In this paper, therefore, cooling oil flow has been calculated to satisfy the limit value of the system temperature by analyzing heat flow considering the related losses such as loss of conductor, contact resistor loss at the conductor connection, and operation loss of motor. And the operation temperature has been set up based on the temperature of crude oil and the heat of motor and conductor. Also, a design for cooling of crude oil pump system has been proposed by calculating the operation pressure loss and selecting the capacity of a cooling oil pump and a heat exchanger.

• Tribology and Lubricants
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• 제20권2호
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• pp.84-90
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• 2004

It is very important to improve the durability and reliability of crankshaft because of conflicting demands for lower fuel consumption and higher power output. In this study, for the crankshaft bearing design, analyses were conducted to determine the lubrication characteristics such as oil flow rate, minimum oil film thickness, friction force and increase of oil temperature at main bearing and connecting rod bearing. Additionally, supplied oil pressure and temperature effects on the bearings were simulated to figure out lubrication characteristics on the bearings. Finally the effects of increasing the bearing width and clearance were introduced on the lubrication characteristics.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.90-95
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• 2004

In this study, for the crankshaft bearing design adapting discontinuous oil supply system, analyses were conducted to determine the lubrication characteristics such as oil flow rate and increase of oil temperature at main bearing and connecting rod bearing. Additionally, supplied oil pressure and temperature effects on the bearings were simulated to figure out lubrication characteristics on the bearings. Finally the effects of increasing the bearing width and clearance were introduced on the lubrication characteristics.

• 전기학회논문지
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• 제60권2호
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• pp.338-343
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• 2011

In this paper, the FT-IR, conductivity and flow electrification phenomena of Vegetable oils were discussed. Vegetable oil has high flash point and eco-friendly properties compared to conventional mineral oil. Accelerated aging transformer oil samples produced in the oven at 140[$^{\circ}C$] for 500 hours, 1000 hours, 1500 hours, 2000 hours. Serial device to measure the flow electrification phenomena was designed and fabricated. Pico ammeter and the Labview data measurements were utilized. The effects of Temperature and antistatic agent on fluid flow electrification were investigated. Both Mineral and vegetable oil showed similar trends for temperature change. The polarity reversal occurred in mineral oil with antistatic agent above 10 ~ 30[ppm] and in vegetable oil with antistatic agent above 5[ppm].

• Tribology and Lubricants
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• 제17권4호
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• pp.335-340
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• 2001

It was reviewed that the kinds of lubricating oil, viscosity, temperature and strength of materials affected the wear of the surface heat treatment. When lubricants is used under severe running conditions, their tribological characteristics are very important. We have studied the lubricating oil viscosity, kinds of additives and their amounts, and lubricating oil temperatures were changed. In order to study the effect of oil temperature on the wear of the surface, the temperature of the oil was changed for the same sample. It was shown from the test results that wear is not greatly affected by the amount of ZnDTP (Zinc dialkyl dithio phosphate) antiwear agent, but EP (Extreme pressure) additives are less effective against wear than ZnDTP additives. The viscosity of lubricating oil and its temperature greatly affect the wear of the surface. Combining all the wear data with those of the surface strength, it was observed that the higher the load, the lower the scratch of wear, and also in the case of the same running load, the lower the wear, the longer the life of the surface strength.

• 설비공학논문집
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• 제14권4호
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• pp.285-292
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• 2002

The vapor pressure and miscibility measurement apparatus was developed and used to obtain data for refrigerant/oil mixture. The vapor pressure and miscibility data for R-404A/32 ISO VG polyol ester (POE) oil mixture and R-404A/46 ISO VG polyol ester oil mixture are obtained over the temperature range from -20 to $60^{\circ}$ with at $10^{\circ}$ intervals and the oil concentration range from 0 to 70 wt%. Using the experimental data, an empirical model was developed to predict the temperature vapor pressure-concentration relations for R-404A/46 ISO VG polyol ester oil mixtures at equilibrium. In the R-404A/32 ISO VG polyol ester oil mixture, the average root-mean-square deviation between measured data and calculated results from the empirical model is 1.24% and in the R-404A/46 ISO VG polyol ester oil mixture, that is 1.37%. Miscibility for R-404A/32 ISO VG polyol ester oil mixture was observed all over the experimental conditions. Immiscibility for R-404A/So1est 46 oil mixture was observed at the low oil concentrations (20~30 wt%) over the high experimental temperature range (50~$60^{\circ}$).

• 한국분무공학회지
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• 제27권3호
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• pp.161-166
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• 2022

To measure the change in friction loss due to the control of fuel mass and oil temperature in a gasoline engine, the floating liner method was used to measure the friction generated by the piston of a single-cylinder engine. First, to check the effect of combustion pressure on friction, the friction loss was measured by adjusting the fuel mass. It was confirmed that the friction loss increased as the fuel mass increased under the same lubrication conditions. In addition, it was confirmed that the mechanical efficiency decreased as the fuel mass increased. Next, to check the effect of lubrication conditions on friction, the friction loss was measured by controlling the oil temperature. It was confirmed that friction loss increased as the oil temperature decreased at the same fuel mass. As the oil temperature decreases, the viscosity increases, resulting in decreased mechanical efficiency and increased friction loss.

• Journal of Advanced Marine Engineering and Technology
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• 제39권6호
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• pp.604-608
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• 2015

본 연구에서는 다심관(Multi Core Tube)에 단열재로 글라스울(Glass wool)을 사용한 단열 다심관(Insulated Multi Core Tube)의 열전달 특성에 관하여 검토하였다. 제작된 단열 다심관에 대하여 외기온도, 유압 오일 공급온도, 유압 오일 공급유량에 따른 단열 다심관 내부의 유압 오일의 온도특성에 관하여 실험 및 모델링을 통하여 검토하였다. 그 결과 본 연구의 범위 내에서 최소 유압 오일 공급유량인 0.29(l/min)인 경우 실험결과와 수치해석 결과의 온도차이가 최대 약 $3^{\circ}C$정도 발생하였다. 외기온도가 일정한 경우 유압 오일 공급온도가 높을수록 유압 오일의 공급유량에 관계없이 유압 오일 출구온도가 높아지고, 유압 오일 공급유량이 1.01(l/min)이상일 경우에는 유압 오일의 온도강하에 외기온도의 영향이 적음을 알 수 있었다.