• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.6
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• pp.543-550
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• 2003

In order to saving the energy for HVAC system of buildings, utilization of wind-induced cross ventilation is thought to be promising. However, utilization of natural ventilation alone is not sufficient for maintaining the human thermal-comfort such as in hot and humid regions. A hybrid air conditioning system with a controlled natural ventilation system, or combination of natural ventilation with mechanical air conditioning is thought to overcome the deficiency of wind-driven cross ventilation and to have significant effects on energy reduction. This paper describes a concept of hybrid system and propose a new type of hybrid system using radiational cooling with wind-induced cross ventilation. Moreover, a radiational cooling system is compared with an all-air cooling system. The characteristics of the indoor environment will be examined through CFD (Computational Fluid Dynamics) simulation, which is coupled with a radiation heat transfer simulation and with HVAC control in which the PMV value for the human model in the center of the room is controlled to attain the target value.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.4
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• pp.385-395
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• 2015

This study evaluated indoor environmental characteristics in an office room equipped both with ventilation window system and central cooling system. Fresh air is supplied only by the central cooling system whereas indoor air is discharged outside through both ceiling diffuser and a ventilation window system. Numerical study is conducted by changing the volumetric flow rates of exhaust ports of each system. For estimating the performance of this coupled system, $CO_2$ concentration and Predicted Mean Vote (PMV) were calculated using Computational Fluid Dynamics (CFD) simulation. The more the ceiling diffuser exhausts indoor air, the more the $CO_2$ concentration decreases. However, when the ventilation window system exhausts more indoor air, thermal comfort level gets improved in the office room with cooling system. Therefore, when the ventilation window system is operated, the coupled operation with central cooling system should be considered for enhancing indoor air quality and thermal comfort, together.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.1
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• pp.8-15
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• 2011

Cooling load reduction was analysed of a ventilation system adopting a regenerative evaporative cooler. The regenerative evaporative cooler is a kind of indirect evaporative cooler which cools the air down to its inlet dewpoint temperature in principle without change in the humidity ratio. The regenerative evaporative cooler was found able to cool the ventilation air to $18{\sim}21^{\circ}C$ when the outdoor condition ranges $25{\sim}35^{\circ}C$ and 0.01~0.02 kg/kg. When the outdoor humidity ratio is lower than 0.018 kg/kg, the regenerative evaporative cooler was found to provide cooling performance enough to compensate the ventilation load completely and to supply additional cooling as well. Energy simulation during the summer was carried out for a typical office building with the ventilation system using the regenerative evaporative cooler. The results showed that the seasonal cooling load can be reduced by about 40% by applying the regenerative evaporative cooler as a ventilation conditioner. The reduction was found to increase as the outdoor temperature increases and the outdoor humidity ratio decreases.

• KIEAE Journal
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• v.4 no.3
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• pp.203-210
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• 2004

This dissertation identifies and investigates the possible control modes of hybrid ventilation system in applying to general apartments. It evaluates range of hybrid ventilation control modes in terms of indoor air quality, thermal comfort, and energy consumption in a living room and a kitchen of the $1000m^2$ apartment. The TRNSYS simulation program was used for evaluating the following four ventilation types : A ventilation mode relying on only infiltration for supplying air, A natural ventilation mode considering with weather condition, A hybrid ventilation (natural + mechanical ventilation) mode allowing minimum ventilation with no heat exchange, and a hybrid ventilation mode with heat exchange. This study shows the following results. As temperature being controlled by heating cooling equipments, there is without significant difference in thermal performance among ventilation types. Regarding Indoor Air quality, Indoor air contamination level of the hybrid ventilation case consistently keep the lower levels. The hybrid ventilation modes consume more energy by a 49% as compared to the A ventilation mode relying on only infiltration for supplying air. It is caused by the continuous ventilation for keeping good indoor air quality; the increase of energy consumption can be attributable to the increase of the heating energy. Therefore, the heat exchange between indoor and outdoor air is required during heating season in severe weather conditions. During the cooling seasons, Introducing natural ventilation can achieve energy saving by 40 ~ 45%. Thus, it can be an effective strategies for energy saving. Based on these results, a hybrid ventilation system can be suggested as an effective ventilation strategy for archiving high level of indoor air quality, thermal comfort, and energy consumption.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.112-121
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• 2006

To evaluate the performance of ventilation system properly, the correlations among the ventilation rate, indoor air-quality and cooling/heating load should be analysed. In this study, simulation tool to analyze the performance of ventilation system was developed. The simulation tool is based on the TRNSYS and some modules to calculate concentration of pollutants with the operation of ventilation system and to decide the signal of ventilation system were newly developed in this study. And these modules coupled with building load and heating/cooling simulation modules. To verify the validity of developed simulation tool, comparison study between simulation and field study were accomplished. As results, the simulation tool developed in this study can be used to predict the performance of ventilation system with accuracy.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.35 no.12
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• pp.41-48
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• 2006

For the Designing a Dedicated Outdoor Air System with Ceiling Radiant Cooling Panels the concept of a dedicated outdoor air system(DOAS) with parallel sensible cooling was born from the decoupled system concept, which can be summarized as decoupling of ventilation and air-conditioning functions, or decoupling of sensible and latent load functions. First , remove the latent loads from the outside air(OA) intake and generated in spaces using a 100% OA ventilation system(i.e., DOAS). Second, remove the space sensible loads using a parallel mechanical cooling system, such as fan coil units, conventional variable air volume , and ceiling radiant cooling panel(CRCP) independent of the ventilation system.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.217-222
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• 2005

Building energy consumption according to the ventilation has been considered to be an important subject. The purpose of this study is to investigate the cooling loads in a test space with a forced ventilating system. In the test space, on/off controlled air-conditioning and forced ventilating facility were operated between 8:30 to 21:00 during 4 days and some important data like temperatures and energy consumption were measured to obtain actual cooling loads. The simulation was carried out in a mode of temperature level control using a TRNSYS 15.3 with a precisely measured air change amount and performance data of air-conditioner. Cooling loads including sensible and latent were compared between by experiment and by simulation. Both of cooling loads associated with ventilation show a close agreement within an engineering tolerance.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.147-152
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• 2015

In order to develop the cooling load estimation method in the greenhouse, the cooling load calculation formula based on the heat balance method was constructed and verified by the actual cooling load measured in the fog cooling greenhouse. To examine the ventilation heat transfer in the cooling load calculation formula, we measured ventilation rates in the experimental greenhouse which a cooling system was not operated. The ventilation heat transfer by a heat balance method showed a relatively good agreement. Evaporation efficiencies of the two-fluid fogging system were a range of 0.3 to 0.94, average 0.67, and it showed that they increased as the ventilation rate increased. We measured thermal environments in a fog cooling greenhouse, and calculated cooling load by heat balance equation. Also we calculated evaporative cooling energy by measuring the sprayed amount in the fogging system. And by comparing those two results, we could verify that the calculated and the measured cooling load showed a relatively similar trend. When the cooling load was low, the measured value was slightly larger than calculated, when the cooling load was high, it has been found to be smaller than calculated. In designing the greenhouse cooling system, the capacity of cooling equipment is determined by the maximum cooling load. We have to consider the safety factor when installed capacity is estimated, so a cooling load calculation method presented in this study could be applied to the greenhouse environmental design.

• Land and Housing Review
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• v.10 no.1
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• pp.25-32
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• 2019

In this study, the case analysis data on underground temperature are presented. In addition, numerical analysis of the ventilation load reduction plan was derived according to the residence schedule change for the building with cool tube. The research scope and method are as follows. The overall system principle was examined through reviewing the theory of the Cool tube system. Case study and analysis were conducted. Numerical simulation was used to examine the change in energy usage. Also, the change of load energy in case of varying amount of ventilation was derived based on actual building room schedule. When the Cool tube system was applied to the residential buildings, the cooling load was reduced from 3,331 kW to 193 kW, which showed a reduction effect of about 90%.The heating load was reduced from 42,276kW to 32,575kW by 23%.Also, result shows that the cooling load decreased by 24% and the heating load decreased by 66% when the number of ventilation according to the occupancy schedule was applied.

• Journal of the Korean housing association
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• v.14 no.3
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• pp.119-126
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• 2003

The purpose of this study is to evaluate the natural ventilation performance for variable external wind speed as a preliminary step to determining the seasonal operating modes of the Double-skin Facade System applied to apartment buildings. For this purpose, two simulation programs are used to compare the Double-Skin Facade System with the Double Sash Window. First, TAS is used to plan a schedule for natural ventilation during the intermediate season and to analyze the cooling loads. Second, CFD is used for a more detailed airflow analysis on a typical floor plan of the model building. The results of the simulations on natural ventilation performance show that the Double-Skin Facade System can reduce the cooling load by 10.5% compared to the Double Sash Window.