• International Journal of Automotive Technology
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• v.7 no.6
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• pp.757-762
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• 2006

Reliability of automotive parts has been one of the most interesting fields in the automotive industry. Especially, a small DC motor was issued because of the increasing adoption for passengers' safety and convenience. For several years, small DC motors have been studied and some problems of a life test method were found out. The field condition was not considered enough in the old life test method. It also needed a lot of test time. For precise life estimation and accelerated life test, new life test procedure was developed based on measured field condition. The vibration condition on vehicle and latent force on fan motor shaft were measured and correlated with each other. We converted the acceleration data into the load data and calculated the equivalent load from integrated value. We found the relationship which can be used for accelerated life test without changing the severity by using different loading factors.

• Journal of Power System Engineering
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• v.21 no.6
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• pp.46-55
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• 2017

Due to the arise of natural disasters caused by global warming, consumers have more interest in the fuel efficiency of their vehicles, and fuel efficiency became an important factor in comparing vehicles. In this market situation, methods to measure fuel efficiency has become one of the main interests of vehicle related organizations and laboratories, and the current method to measure fuel efficiency is to follow the notification established by the ministry of trade, industry and energy, ministry of environment, and the ministry of land, infrastructure and transport. In this study, we analyze the influence of vehicle fuel efficiency according to test temperature and cooling fan condition which have the possibility to cause difference in fuel efficiency. The analysis results of the influence of the fuel efficiency according to the test temperature, the difference of the fuel efficiency of the test temperature ($21{\sim}29^{\circ}C$) within the allowable range of the notification showed a maximum difference of 2.9%. Therefore, it is necessary to consider the introduction of a test method that permits only the temperature change based on the reference point as the allowable range even in the test within the allowable range. The analysis of the influence of the fuel efficiency according to the cooling method showed no significant effect, and it seems reasonable to maintain the test method of the current notification.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.59-64
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• 2014

Integrated Starter Generator (ISG) system improves the fuel economy of hybrid electric vehicles by using idle stop and go function, and regenerative braking system. To obtain the high performance and durability of ISG motor under continuously high load condition, the motor needs to properly design the cooling system (cooling fan and cooling structure). In this study, we suggested the enhanced design by modifying the thermal design of the ISG motor and then analyzed the improvement of the cooling performance under high-speed condition and generating mode by CFD simulation. The temperatures at the coil and the magnet of the enhanced model were decreased by about $4^{\circ}C$ and $6^{\circ}C$, respectively, compared to those of the conventional model. Therefore, we verified the cooling performance enhancement of the novel thermal design in the case of core loss increment due to the higher speed condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.264-269
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• 2001

Axial fans are widely used in household electrical appliances due to their easy usage and high flow rate for cooling capacity. At the same time, the noise generated by these fans causes one of serious problems. In order to calculate the noise of a fan, we develop the software IFD - Intranet Fans Design. With this software we can design, analysis the performance and predict the noise of fan. The prediction model, which allowed the calculation of acoustic pressure at the blade passing frequency and it's higher harmonic frequencies, has been developed by Lowson's equation. To calculate the unsteady resultant force of the blade, time-marching free-wake method is used. The objective of this study is to calculate the effects of number of blades, rotating velocity, and sweep angle on the noise of fan..

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.83-88
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• 2004

In this study, the flow and thermal performance of the heat sink and fan-sink were experimentally studied to predict the operating condition of the fan-sink. The experiments of the flow and thermal resistance of the heat sink with various inlet blockage, which were occurred by the shapes of the axial fans, were conducted for the proof of the effects of the inlet blockages. The greater the inlet blockage of the heat sink, the higher the pressure drop and lower the thermal resistance of the heat sink will be. The operating point of the fan-sink was predicted by the pressure drop curve with the inlet blockage, which was corresponded to the selected fan and the fan performance curve, and verified by the performance test of the fan-sink. The predicted operating point of the fan-sink had good agreement with the result of the performance test of the fan-sink within $0.7\%$ of the volume flow rates. Measured thermal resistance of the fan-sink was equivalent to that of the heat sink with the same inlet blockage of the fan-sink. It was shown that the heat transfer characteristics of the heat sink were influenced by the flow interaction between the selected fan and the heat sink. To improve the thermal resistance of the heat sink, it is necessary to consider appropriate flow patterns of the fan outlet entering into the heat sink.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.730-736
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• 2008

The purpose of this study is to find out a flow characteristics when a crossflow-fan is installed inside the computer case and to provide information about the preliminary data of cooling efficiency of CPU and a flow inside and outside of a computer case. Under the condition of operating the fan inside the experimental duct we changed the position of a installation of the slot, and the experiment measured with PIV and the results are as follows. Under the influence of the crossflow-fan installed to the air discharging side, mean velocity between 35 to 45 on the point 80 of the Slot 0.2.3 of the case increased and it influences discharging the air inside of the computer case. On the left-upper end. which isn't directly influenced by the suction-discharging fan installed inside the PC, a flow occurs caused by vortex due to the Sirocco-Fan and Slot installed on the center of the right side. We can see that a flow distribution increases when the Sirocco-Fan operates and a whirl appears stronger between the slot and the suction fan. It is thought that this phenomenon is influenced by a flow while it is on the way of entering from the suction-fan and going out to the discharging-fan.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.4
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• pp.91-98
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• 2014

In this study, the first and second electronically controlled cooling systems for a bimodal tram were developed. The performance characteristics of the cooling systems were assessed experimentally with actual and identical conditions, and a simulation was run using ANSYS Fluent. The results of the experimental and FEA method were standardized. In order to confirm the reliability of the experimental method, the experiment was carried out by a testing institution. The low-volume flow-rate condition was found to be better, but the cooling system performed in a minimal condition. Therefore, it is important to find the optimum performance levels. The cooling system equipment was revised to determine the optimized design parameters, after which the cooling performance levels increased at the radiation area. Specifically, with a greater fan diameter. Through this study, the newly developed cooling system will be reevaluated after being mounted on an actual bimodal tram. This will lead to a completely domestically produced bi-modal tram cooling system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.775-780
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• 2013

In recent years, a notebook like an ultrabook gets thinner. Its thickness causes problems in cooling fan performance, system installation condition, and so on. In this study, we installed a small turbofan in notebook system with very narrow gap in order to generate similar condition to a real product. Experiments were performed to measure the fan's performance and the flow and noise characteristics, its results were compared with computational ones. Prediction of P-Q curve using CFD showed under about 5% error in high flow rate and its trend was agreed with experimental one over the flow field. Experimental data to measure the noise at a distance of 100 mm from a rotation axis direction of an impeller corresponded well with computational ones of broadband and BPF noise. The noise experiments to measure at a distance of 100 mm from a rotation axis direction of an impeller corresponded well with computational ones of broadband and BPF noise. Especially, tip part of impeller blade and part of exit and bottom near in an analysis by a commercial program(FlowNoise).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.407-412
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• 2000

Response surface method is employed in optimizing the acoustic performance of automotive engine-cooling axial fans. The effects of modifications in blade geometry on noise reduction are investigated. Taking the far-field noise level as the objective, a quadratic response surface is constructed utilizing D-Optimality condition as the candidate-points selection criteria. It is shown that the quadratic model exhibits an excellent fitting capability resulting in the blade design with low far-field noise level.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.33-38
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• 2011

In this paper, the effect of pulse current and generated heat on characteristics of the LED is measured and evaluated. For experiments, the LED driving circuit and digital logic which determines period and duty ratio of lighting are designed. At rated current, the temperature and optical characteristics of the LED with change in duty ratio and period are compared, and those of the LED with change in duty ratio and existence of cooling fan are also compared at constant average current. As a result, frequency does not affect device temperature and optical characteristic of the LED but duty ratio does. Also, the cooling fan is less effective on those of the LED at rated current.