• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.71-80
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• 2015

This paper proposes a convenient thermal modeling method for loss distribution control method of 3-level Active NPC(Neutral Point Clamped) inverter. In the drawback of conventional 3-level NPC, the generated losses can occur unbalance in each switching device, as a result, thermal utilization of designed system has been decreased. In order to compensate unbalanced losses, Active NPC inverter performed loss balancing control with thermal modeling during operation of each switching device. Therefore, this paper deals with a convenient thermal modeling method based on newton's law of cooling rather than conventional thermal modeling method. Both simulation and experimental results based on 10kW 3-level Active NPC inverter confirm the validity of the analysis performed in the study.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.183-186
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• 2007

The injection molding process has high accuracy and good reproducibility that are essential for mass production at low cost. Conventional molding processes typically use the water-based mold heating and air cooling methods. However, in the nano injection molding processes, this semi-active mold temperature control results in the several defects such as air-flow mark, non-fill, sticking and tearing, etc. Therefore, in order to control temperature of the molds actively and improve the quality of the molded products, the novel nano injection molding system, which uses active heating and cooling method, has been introduced. By using the Peltier devices, the temperature of locally adiabatic molds can be controlled dramatically and the quality of the molded patterns can be improved.

• Transactions of Materials Processing
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• v.17 no.5
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• pp.337-342
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• 2008

The injection molding process has high accuracy and good reproducibility that are essential for mass production at low cost. Conventional molding processes typically use the water-based mold heating and air cooling methods. However, in the nano injection molding processes, this semi-active mold temperature control results in the several defects such as air-flow mark, non-fill, sticking and tearing, etc. In order to actively control temperature of the molds and effectively improve the quality of the molded products, the novel nano injection molding system, which uses active heating and cooling method, has been introduced. By using the Peltier devices, the temperature of locally adiabatic molds can be controlled dramatically and the quality of the molded patterns can be improved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.551-552
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• 2010

• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.33-38
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• 2011

Medicated water electrolysis apparatus, which electrolyzes water into acidic water and alkaline water, was in the spotlight as becoming known the effect of alkaline water. It is known as good for health as removing active oxygen in the human's body and promoting digestion. But, the customers could not get that desired water temperature because these apparatuses are directly connected with a water pipe. So, the cooling system was developed for controlling the temperature of the alkaline water. One of the typical way is to store water in water tank and control the temperature. But, in this way, storing water can be polluted impurities coming from outside. For protecting this pollution, the cooling system based on indirect heat exchange method through phase change between water and ice was developed. In this study, we have calculated efficiency of the cooling system with phase change by experiment and commercial CFD(Computational Fluid Dynamics) code, ANSYS CFX. To consider the effect of latent heat that is generated by melting ice, we have simulated two phase numerical analyses used enthalpy method and found the temperature, velocity, and ice mass distribution for calculating the efficiency of cooling. From the results of numerical analysis, we have obtained the relationship between the cooling efficiency and each design factor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1615-1620
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• 2010

A thin film thermoelectric cooler for COB direct assembly was proposed and the COB cooler structure was modeled by electrical equivalent circuit by using SPICE model of thermoelectric devices. The embedded cooler attached between the die chip and metal plate can offer the possibility of thin film active cooling for the COB direct assembly. We proposed a driving method of TEC by using pulse width modulation technique. The optimum power to the TEC is simulated by using a SPICE model of thermoelectric device and passive components representing thermal resistance and capacitance. The measured and simulated results offer the possibility of thin film active cooling for the COB direct assembly.

• Journal of Power System Engineering
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• v.21 no.3
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• pp.85-92
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• 2017

Global air traffic is forecast to grow at an average annual rate of around 5% in the next 20 years. The continuous growth of air traffic and raised environmental awareness put increasing pressure on aero engine manufacturers to reduce fuel burn and emissions. NEWAC are a new integrated program of the European Union with focus on innovative core engine concepts to achieve this problem. In this paper, Within NEWAC, active core engine configurations will be investigated. the investigation is focused on the optimal design of the CAC heat exchanger for active core. For optimal design of he CAC heat exchanger, the HTFS of basic design of heat exchanger are analyzed so as to proceed an optimization routines based on Response Surface Method(RSM) and Design of Experiment(DOE). As a result, CAC heat exchanger optimized by 1.0314 lb/s mass flow rate and 3.9058 mm TP of tube layout and 206.8181 mm height of heat exchanger and 918 tube number for heat transfer and pressure drop. We confirm the design optimization using RSM and DOE is useful on complex structure of heat exchanger.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.513-516
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• 2008

We have replicated nanopillar arrays using injection molding process of active heating and cooling method by several peltier devices. The injection melding has a high accuracy ed good reproducibility that are essential for mass production at low cost. Conventional molding processes widely use the water-based mold heating and air cooling methods. However, in case of replication for nano-patterned structures, it caused several defects such as air-flow mark, non-fill, sticking and tearing. In this study, periodic nano-scale patterns are replicated by using injection molding with Peltier devices. Porous nano-scale patterns, which have pore diameter range from 120nm to 150nm, were fabricated by using anodizing process. Periodic nano-pore structures ( $20mm\;{\times}\;20mm$) were used as a mold stamp of injection molding. Finally, PMMA with nanopillar arrays was obtained by injection molding process. By using the Peltier devices, the temperature of locally adiabatic molds can be dramatically controlled and the quality of the molded patterns can be slightly improved.

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

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.284-292
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• 2009

The stack-effect in high-rise buildings in winter causes many problems such as difficulties in opening or closing doors, infiltration, energy loss, noise and fire protection. Stack effect is influenced by temperature difference between the interior and exterior of building and the height of building. As an attenuation method for stack effect, the architectural methods are generally used. However, as though architectural methods were fully adopted, the problems are reported as ever in tall building. In this study, a new method to reduce stack effect will be suggested. As an active control method against the stack effect, E/V shaft natural cooling method is suggested. In this paper, the concept of E/V shaft natural cooling system and its reduction performance of stack effect by simulation and field measurement will be reported.