• Journal of IKEEE
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• v.26 no.4
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• pp.671-680
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• 2022

In this paper, A 200kW traction motor driver that covers most of the traction motor specification of commercial electric vehicles (EV) is developed. In order to achieve high efficiency and high power density, a next-generation power semiconductors (Silicon carbide, SiC) are applied instead of power semiconductor(IGBT), which is Si based. Through hardware analysis for optimal use of SiC, expected efficiency and heat dissipation characteristics are obtained. A vector control algorithm for an IPMSM (Interior permanent magnet synchronous motor), which is mostly used in EV(Electric vehicle) traction motor, is implemented using DSP (Digital signal processor). In this paper, a prototype traction motor driver based SiC for EV is designed and manufactured, and its performance is verified through experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.72-78
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• 2022

A vacuum brazed cooling passage for an aircraft engine controller was designed. In order to predict the total pressure loss, which is the main design factor of the cooling passage, theoretical and numerical methods for the major loss and the minor loss considering the overall shape of the cooling passage are presented. This design and evaluation method can predict the pressure loss of the complex cooling passage shape for various flow conditions at the initial design step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4725-4732
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• 2012

This paper studies MR16 that can strengthen the strength and make up for the weakness of MR16 by replacing halogen light source using multifaceted Reflector(MR16) with LED light source. To achieve this, developed MR16 for LED applying optical system that four aspheric lens is one sheet. Optical system is designed by optics software and lighting performance of the designed data is predicted lighting simulation program. Also, heatsink's heat radiation analysis program to predict the thermal performance. Finally, optical prototype system based on simulation analysis data is manufactured and the results comparing performance of the developed system and the designed data are follows: Radiation angle was around $50^{\circ}{\sim}60^{\circ}$ in results of simulation analysis and the test of the prototype system. Also, temperature measurement result indicates that the thermal equilibrium is realized after one minute and thirty seconds and heat is generated up $60^{\circ}C$ in all of simulation analysis and the test of the prototype system. Finally, simulation analysis result on light disturbance curve of MR16 is similar to that of performance of the prototype system.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.62-67
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• 2019

This study was focused on the design and the performance analysis of integral Hot BoP for recovering waste heat from high-temperature exhaust gas in 2 kW class solid oxide fuel cell (SOFC). The hot BoP system was consisted of a catalytic combustor, air preheater and steam generator for burning the stack exhaust gas and for recovering waste heat. In the design of the system, the maximum possible heat transfer was calculated to analyze the heat distribution processes. The detail design of the air preheater and steam generator was carried out by solving the heat transfer equation. The hot BoP was fabricated as a single unit to reduce the heat loss. The simulated stack exhaust gas which considered SOFC operation was used to the performance test. In the hot BoP performance test, the heat transfer rate and system efficiency were measured under various heat loads. The combustibility with the equivalent ratio was analyzed by measuring CO emission of the exhaust gas. As a result, the thermal efficiency of the hot BoP was about 60% based on the standard heat load of 2 kW SOFC. CO emission of the exhaust gas rapidly decreased at an equivalent ratio of 0.25 or more.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.638-644
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• 2019

In this study, the fluid flow and heat transfer characteristics within sandwich panels are investigated using computational fluid dynamics. Within the sandwich panels having periodic cellular cores, air can freely move inside the core section so that the structure is able to perform multi-functional roles such as simultaneous load bearing and heat dissipation. Thus, there needs to examine the thermal and flow analysis with respect to design variables and various conditions. In this regard, ANSYS Fluent was utilized to explore the flow and heat transfer within the pyramidal truss sandwich structures by varying the truss angle and inlet velocity. Without the entry effect in the first unitcell, the constant rate of pressure and the constant rate of Nusselt number was observed. As a result, it was demonstrated that Nusselt number increases and friction factor decreases as the inlet velocity increases. Moreover, the rate of Nusselt number and friction factor was appreciable in the range of V=1-5m/s due to the transition from laminar to turbulent flow. Regarding the effect of design variable, the variation of truss angle did not significantly influence the characteristics.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.1-10
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• 2011

Unfortunately, in current microprocessors, increasing the frequency causes increased power consumption and reduced reliability whereas it improves the performance. To overcome the power and thermal problems in the singlecore processors, multicore processors has been widely used. For 2D multicore processors, interconnection is regarded as one of the major constraints in performance and power efficiency. To reduce the performance degradation and the power consumption in 2D multicore processors, 3D integrated design technique has been studied by many researchers. Compared to 2D multicore processors, 3D multicore processors get the benefits of performance improvement and reduced power consumption by reducing the wire length significantly. However, 3D multicore processors have serious thermal problems due to high power density, resulting in reliability degradation. Detailed thermal analysis for multicore processors can be useful in designing thermal-aware processors. In this paper, we analyze the impact of workload distribution, distance to the heat sink, and number of stacked dies on the processor temperature. We also analyze the effects of the temperature on overall system performance. Especially, this paper presents the guideline for thermal-aware multicore processor design by analyzing the thermal problems in 2D multicore processors and 3D multicore processors.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1016-1021
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• 2011

The enhancement for cooling performance of heat sink is surely necessary to guarantee the performance of electronic products. So in this paper, the cooling performances of the aluminum heat sink with pulsating heat pipe(PHP) were investigated experimentally and numerically. The pulsating heat pipe was used as a heat spreader. Working fluid of PHP was R-22. Heat inputs were 30W, 60W, 80W and 100W, respectively. Heat sink was tested for forced convection conditions with air velocity of 1 ~ 4m/s. And CFD simulations were conducted for two different heat sinks. The results showed that the cooling performance of heat sink with pulsating heat pipe was higher than that of conventional heat sink. Therefore, the pulsating heat pipe can be a good tool to improve cooling performance of heat sink.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.12-19
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• 2004

A Molded Case Circuit Breaker (MCCB) is an electric control device to interrupt the abnormal currents which result from the over-loads or short-circuits. Its malfunction will result in severe accidents. In the development of the MCCB, higher current-rating and improved thermal performance become more and more important in providing the safe function and reliability for the modern devices requiring small scale and high performance. It is also very important to consider the factors of temperature rise in the design of MCCB. The major reasons of temperature rise in the MCCB result from the resistances, which are come from the connection and contact surfaces. These resistances are influenced by current, time, configuration of contact surfaces and applied voltage. In order to predict the temperature distribution inside MCCB, we have simulated the model with some assumptions and simplifications, using commercial code ICEPAK. To verify the results of temperature field analysis, the numerical results are compared with experimental ones for the same model. The results show a good agreement with actual temperature rise obtained by experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.66-72
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• 2016

An LED lighting control system was developed to combine information technology and LED lights for efficient management and energy savings. The system can monitor and control the status of an LED luminaire using Bluetooth wireless communication, sensor technology, and smart phones. An LED lighting control circuit was designed using a temperature sensor, illumination sensor, and Bluetooth module with a fuzzy constant-current control circuit. We extended the lifetime and prevented damage to the LED by optimizing the supply current of the LED luminaire based on the heat-generation temperature of $70^{\circ}C$ of an LED heat sink. We also automatically adjusted the ON/OFF time depending on the ambient illumination of the LED luminaire. By allowing easy control of the LED luminaires on a smartphone, we improved the efficiency and achieved energy savings. The control system was validated through experiments for normal operation.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.42-50
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• 2017

A study has been conducted to develop an aluminum EGR cooler for the LPL EGR system of a diesel engine. Aluminum has a much lower density and thermal conductivity that is about 12 times or more than that of stainless steel, so it is advantageous for use in an EGR cooler for weight reduction and cooling performance effects. A design process has been carried out to ensure heat dissipation performance in a restricted space to investigate the geometric parameters and satisfy the requirements for pressure drops at both fluid sides. The tubes of exhaust gas have been designed as extruded tubes. An aluminum EGR cooler consisting of extruded tubes entails a simpler manufacturing process compared to a stainless steel EGR cooler with conventional heat transfer fins. A prototype has been manufactured from the final model selected through the design process. The performance of the aluminum EGR cooler was evaluated and compared with that of the conventional one. The weight of the aluminum EGR cooler is reduced by 22.9%, while performance is significantly improved.