• Journal of the Korea Convergence Society
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• v.13 no.3
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• pp.191-196
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• 2022

Unlike an international combustion engine car, a battery-powered electric vehicle requires an additional heat source for its heating system. A high-voltage coolant heater has the advantages of high efficiency and a wide operating temperature range. In its development, the geometry design of the coolant flow path is essential. This paper presents the thermal flow simulations of a 7kW high-voltage heater with symmetric serpentine flow channels arranged parallelly. The heater performance was evaluated from the simulation results in terms of the pressure and temperature differences and the flow uniformity. The proposed design showed a greater flow resistance and similar heat exchanging capability than the existing parallel serpentine design. It has the advantage of a relatively wide low-temperature surface area, where the control circuit board susceptible to high temperatures can be located.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.703-709
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• 2017

Korea Utility Helicopter(KUH) is a project to replace the aging helicopter presently being operated by the military with a domestic helicopter. The auxiliary power unit is a device that supplies emergency power to the system by an alternator installed when the main generator fails and the start motor converts the electrical energy of the battery into mechanical rotational energy to rotate the auxiliary power unit engine. With continuing power and operation, defects of the starting motor were found and improvements were carried out to solve it. In the failure mode analysis, the causes of possible defects were classified into 5 categories. Analysis of the 5 factors revealed that the main cause of defects is mechanical wear, which was found to be related to spring pressure. 250 tests were conducted through the theoretically determined pressure and regression analysis was performed with 4 sampling.The results showed that pressure was related to wear rate. In conclusion, early wear and breakage due to wear can be controlled through spring force and test showed the prediction of wear and the validity of the result were confirmed.