• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.451-454
• /
• 2003

The Oil Coolers is very important unit for the stable thermal performance in machine tools, semiconductor equipments and high precision measuring systems. To select a proper oil cooler for the temperature control of core unit in a machine, not only cooling ability but also static and dynamic sensitivity of temperature sensors are considered. In this paper, the relationship between cooling ability and inflow oil temperature is identified. The cooling ability is increased with the increase of inflow oil temperature. The oil temperature control errors of a cooler are influenced by mainly sensitivity of temperature sensors and heating velocity in a machine. The validity of error cause analysis for temperature control is proved by real cooling experiments with inflow and outflow temperature sensors.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.2 no.4
• /
• pp.11-16
• /
• 2003

Recently, CNC lathe is in need of higher speed for precision works. So more intensive and compact heat exchanger is necessary to cool down the heat in short time from drills and works during high speed working. In this study, to increase heat transfer coefficient per unit volume, inner groove tube is designed and compact oil cooler, 57% volume of conventional type, is manufactured. The heat transfer performance is experimented and is compared with the performance of conventional type.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.955-960
• /
• 2009

In order to improve the efficiency of the main transformer in a tilting train, the optimal operation of a cooling system is necessary. Mathematical models of a main transformer cooling system were developed. These include models for the main transformer, the oil pump, the oil cooler, and the blower. The optimal oil temperature algorithm was also developed. This consists of the optimal setpoint algorithm and the control algorithm. A simulation program was developed by using mathematical models and the optimal oil temperature algorithm. Simulation results showed that the dynamic behavior of a main transformer cooling system was predicted well by mathematical models and a main transformer cooling system was controlled effectively by the optimal oil temperature algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.10a
• /
• pp.277-277
• /
• 2003

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.22-29
• /
• 2008

In order to improve the efficiency of a main transformer in a tilting train, the optimal operation of a cooling system is necessary. For the development of optimal control algorithms of a cooling system, mathematical models of a main transformer cooling system were developed. These include dynamic models of a main transformer, an oil pump, an oil cooler, a blower, and a pipe. Control algorithms for a blower and an oil pump were selected in order to identify the effectiveness of dynamic models. A simulation program was developed by using the developed dynamic models and the selected control algorithms. Simulation results showed good predictions of dynamic behaviors of a main transformer cooling system. Therefore, dynamic models, which were developed in this study, may be effectively used to develop control algorithms of a main transformer cooling system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.62-67
• /
• 2003

In this Paper, the dynamic temperature sensitivity and mu. temperature measurement errors of oil and air sensor in oil cooler are evaluated to predict design validity of sensors under special oil and atmosphere temperature changes. The temperature tracking of oil sensors for periodic temperature changes is simulated by obtaining thermal response coefficient from experiment. By this method, it is possible to design the optimal sensors with the admitted temperature measurement errors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.10a
• /
• pp.354-355
• /
• 2010

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.687-692
• /
• 2016

When turbochargers are applied to engines, the temperature of the engine becomes high, making the cooling of pistons very important. To solve this problem, an oil jet is used. The oil jet provides oil to the underside of piston for cooling. When an oil jet is used, oil pump size-up and oil cooler are needed because of the increased oil flow rate and higher oil temperature. On the other hand, these increase the friction torque of the engine. This study examined how much the friction torque of an engine increases by an oil jet, oil cooler, and oil pump size-up. In addition, the proportions of the friction torque of the engine increased by each part were measured by changing the engine assembly condition. At low speed, the oil pump and oil cooler had a larger effect on the friction torque than the other factors. At high speed, oil cooler had a larger effect than the other factors.

• Tribology and Lubricants
• /
• v.25 no.6
• /
• pp.387-398
• /
• 2009

The operation condition of recently designed pistons for high power and high speed diesel engine become more severe due to the increment of combustion pressure and temperature. So, in order to overcome high temperature, the application of the mono-metal cast aluminum alloy piston featuring an enclosed cast-in open cooling gallery has increased. In this research, it is developed a PCJ (piston cooling jet) rig tester, described the test procedure and validated the performance of sample piston cooling gallery design. Then the test rig will be used for developing the design technology of piston cooling gallery. The test rig is composed with oil reservoir and pumping system, oil jet system, piston fixing and moving system, collecting oil measuring system, and data measuring and recording system. It will be measured collecting efficiencies under conditions of a few piston positions, oil jet pressures and oil viscosities for a piston cooling gallery. Furthermore, the PCJ rig tester will be used for the optimum design of the oil cooling gallery which being applied to increase the cooling efficiency of pistons in diesel engines satisfying the EURO V emission regulation and the more.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.668-669
• /
• 2016

The retarder as a hydraulic brake system in order to assist a service brakes in commercial vehicle is operated by automatic and manual mode due to driver. Braking energy by retarder operation is transmitted to the engine radiator of vehicle cooling system, passing through the retarder oil heat exchanger. At this moment, the retarder ECU performs the function that is controlled a braking torque with consideration for automatic and manual mode, temperature of retarder oil/water, engine coolant temperature, vehicle speed, and etc. In this paper, it deals with the design of retarder control logic and the results of retarder braking performance test regarding a cooling system of retarder and vehicle.