• Journal of the Korean Solar Energy Society
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• v.38 no.4
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• pp.67-76
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• 2018

Cooling the building by natural ventilation is one of the passive methods widely used from ancient times. It can be effectively applied especially in case of cooling load during the intermediate season of the year. In this study, the effect of 4 cases of window ventilation control mode which are 'Always Close', 'Temperature', 'Enthalpy' and 'Always Open' is simulated by Energyplus program and analyzed to improve the comfort of occupants and reduce energy consumption of the school classroom.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.328-334
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• 2013

A greenhouse heating system to improve heat pump performance using inside and outside air of greenhouse as a heat source selectively and cut $CO_2$ enrichment costs by delay of greenhouse ventilation was developed. In this system, thermal storage modes divided into inside circulation mode using surplus solar energy and outside circulation mode using outside air heat. The thermal storage modes were designed to be switched mutually according to inside greenhouse temperature and six temperature values were input to control the heat pump operating, thermal storage mode switching and greenhouse heating automatically. Operating characteristics of this system were tested in a plastic greenhouse of non-ventilation condition. The results of test showed that the inside circulation mode began at about 11:00 and lasted for about 210 minutes and inside greenhouse temperature was maintained between $20{\sim}28^{\circ}C$ in spite of non-ventilation. System heating COP of the inside circulation mode in the daytime was 3.35, which was 36% and 25% higher than that of the outside circulation modes in the nighttime and daytime respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.335-338
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• 2009

The process of charging an oxidizer in the liquid propellant rocket can divide into the cooling of the oxidizer tank, the high flow charge, the small flow charge, and the replenishment charge for the correction of temperature. The oxidizer of the Naro(KSLV-I) first stage uses the liquid oxygen. And the flow rate and the temperature specification corresponding to each charge mode are presented for the requirement. The flow throttling valve and heat exchanger are installed in the oxidizer filling system in order to satisfy this kind of the flow rate and temperature requirement specification. In this research, by using the Flowmaster which is a commercial one-dimension thermo-fluidic analysis program, one dimensional flow system analyses was performed to predict the exact flow rate at each specific mode. Also, the flow rate correction sensitivity of the flow control valves was analytically determined to satisfy the flow condition refinement at each mode within the limited certification test.