• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.4
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• pp.179-186
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• 2015

In this study, the actual energy consumption of the secondary side District Heating System (DHS) with different hot water supply temperature control methods is compared. The two methods are Outdoor Temperature Reset Control and Outdoor Temperature Predictive Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side system, the results show that the Outdoor Temperature Predictive Control method saves more energy. In general, the Outdoor Temperature Predictive Control method lowers the supply temperature of hot water, and it reduces standby losses and increases the overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, the Outdoor Temperature predictive Control method saves about 6.6% of energy when compared to the Outdoor Temperature Reset Control method. Also, it is found that at partial load condition, such as during daytime, the fluctuation of hot water supply temperature with Outdoor Temperature Reset Control is more severe than that with Outdoor Temperature Predictive Control. Thus, it proves that Outdoor Temperature Predictive Control is more stable even at partial load conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.3
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• pp.137-145
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• 2015

In this study, the actual energy consumption of the secondary side of District Heating System (DHS) with different hot water supply temperature control methods are compared. Three methods are Set-point Control, Outdoor Temperature Reset Control and Outdoor Temperature Prediction Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side of the system, the results show that Outdoor Temperature Prediction Control method saves more energy. In general, Outdoor Temperature Prediction Control method lowers the supply temperature of hot water, and it reduces standby losses and increases overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, Outdoor Temperature Prediction Control method saves about 7.1% in comparison to Outdoor Temperature Reset Control method and about 15.7% in comparison to Set-point Control method. Also, it is found that at when partial load condition, such as daytime, the fluctuation of hot water supply temperature with Set-point Control is more severe than Outdoor Temperature Prediction Control. Therefore, it proves that Outdoor Temperature Prediction Control is more stable even at the partial load conditions.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.4
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• pp.8-14
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• 2016

In this study, the effects of prediction and reset control of outdoor air temperature on energy consumption for central heating system are researched by using TRNSYS program package, and the control performances with the suggested methods of prediction and reset control of outdoor air temperature are compared with the existing ones. As a result, the value of coefficient of determination $R^2$ for the predicted outdoor temperatures is improved and the suggested control method shows maximum 21.8% energy saving in comparison with existing control ones.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.2
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• pp.30-36
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• 2011

In this study, energy saving performance of outdoor temperature reset control strategy for central cooling system is researched by experiments. Outdoor temperature reset control is the control method to change indoor air set temperature according to outdoor air temperature change. The range of indoor air set temperature is represented by the comfort temperature range of indoor air temperature offered from ASHRAE and indoor air set temperature is programmed between $22^{\circ}C$ and $27^{\circ}C$ by outdoor air temperature $20^{\circ}C{\sim}32^{\circ}C$ in summer. As a result of applying outdoor temperature reset control to central cooling system, the suggested control method shows better performances of energy savings than the conventional method which indoor temperature maintains constantly.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.11
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• pp.1165-1173
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• 2001

The objectives of this study are to analyze the application of radiant floor cooling and to evaluate the control methods through experiments when the radiant heating system is used for cooling. Through the experiment analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The cooling curve (reset ratio) is found for radiant cooling, which shows tole relation between outside air temperature and supply water temperature. Comparison of cooling methods shows that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.6
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• pp.532-540
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• 2001

The objectives of this study are to analyze the control variables according to condensation occurrence, to find the range in floor surface temperature and frequency of condensation, and to evaluate the control methods through simulations when the radiant heating system is used for cooling. Through the simulation analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The results show that the lowest floor surface temperature is around $23^{\circ}C$, the surface condensation can be prevented by controlling indoor humidity within 20g/kg(DA0, and that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1073-1074
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• 2008

This paper presents outdoor reset control based on fuzzy algorithm for radiant floor heating system. We construct fuzzy system under indoor temperature and outdoor temperature. Simulation is based on TRNSYS with MATLAB. MATLAB is calculating and decide heat source using fuzzy system. Energy efficiency of Fuzzy algorithm is analyzed in term of indoor by TRNSYS System.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.12
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• pp.830-836
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• 2012

In this study, the effects of heating control methods on heating control performance and energy consumption in the floor radiant heating control system of residential apartments were research by computer simulation. A general regression neural network(GRNN) control method for reducing indoor temperature overshoot and saving energy in floor radiant heating system is suggested. The GRNN control method shows good responses in comparison with the conventional and outdoor reset control methods for improving indoor thermal environment and reducing energy consumption.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.4
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• pp.1-7
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• 2012

In this study, computer simulation for demand control strategies to save the electric energy and power price in the building central cooling system is done. The demand control and outdoor reset control algorithms are applied by consideration the electric energy and power price according to the energy consumption characteristics. The suggested control methods show better responses in the power price and energy consumption in comparison with the conventional one.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.12
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• pp.572-578
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• 2014

Heating energy was measured in an apartment housing unit with a district heating system, varying the kind of hot water distributors. Ondol coils passing through a living room raised the temperature of the room where the heating was turned off. Including this characteristic of Ondol heating into the modeling, we performed simulations and showed a verification by comparison with the results of measurements. As a result, a main flow control method, which changes hot water flow rate supplied to a housing unit according to the thermal load, can reduce the supplied flow rate and lower the return temperature, compared with a constant flow method. That can result in decreased heat loss in utility-pipe conduits even though the heating energy supplied is almost the same. An outdoor reset control that raises the temperature of the supplied hot water if the outdoor temperature falls has the effect of a quicker response in heating than the reduced flow rate and return temperature.