• Proceedings of the KSME Conference
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• 2001.06d
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• pp.164-169
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• 2001

There is a chilled ceiling panel which carries out the air conditioning by radiation and convection between the room and cold ceiling panel surface. In order to verify heat transfer characteristics between them in cooling system with radiant chilled ceiling panel, analytical and experimental studies were performed for various design and operating parameters such as tube space and diameter, inlet water temperature, mass flow rate, cooling load, and so on. In this study, we found that the tube space and inlet water temperature were more important elements than the tube diameter and water flow rate for the performance of radiant chilled ceiling panel. The cooling capacity of the radiant chilled ceiling panel had the maximum value of $65W/m^{2}$ because the highest cooling capacity was limited by the condensation on the panel surface. The results of comparison between numerical analysis and experiment showed a resonable agreement qualitatively, especially for low cooling capacity.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.305-313
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• 2012

We conducted thermal analyses and cooling tests of the space observation camera (SOC) of the multi-purpose infrared imaging system (MIRIS) to verify passive cooling. The thermal analyses were conducted with NX 7.0 TMG for two cases of attitude of the MIRIS: for the worst hot case and normal case. Through the thermal analyses of the flight model, it was found that even in the worst case the telescope could be cooled to less than $206^{\circ}K$. This is similar to the results of the passive cooling test (${\sim}200.2^{\circ}K$). For the normal attitude case of the analysis, on the other hand, the SOC telescope was cooled to about $160^{\circ}K$ in 10 days. Based on the results of these analyses and the test, it was determined that the telescope of the MIRIS SOC could be successfully cooled to below $200^{\circ}K$ with passive cooling. The SOC is, therefore, expected to have optimal performance under cooled conditions in orbit.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.203-208
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• 2009

This paper presents demonstration study results derived through field testing of a solar assisted cooling and heating system for the library of a cultural center building located in Gwangju, Korea. The area of demanded cooling and heating for building was about 350m2. Solar hot water was delivered by means of a 200m2 array of evacuated tubular solar collector (ETSC) to drive a single-effect (LiBr/H2O) absorption chiller of 10RT nominal cooling capacity. From March in 2008 to February in 2009, demonstration test were performed for solar cooling and heating system. After experiments and analysis, this study found that solar thermal system was 84% for the solar hot water supply and 12% for space heating and 4% for space cooling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.641-651
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• 2003

In order to assess the reliability of a building energy simulation program (TRNSYS) from the standpoint of user, a set of verification experiment and calculation of cooling load for a test space is carried out. This work is a complement of the previous study that dealt with heating load for the same space. The test space is kept airtight to eliminate the source of uncertainties in modeling. A window-mounted, on/off controlled air-conditioner is used for cooling, whose performance has been established a priori. The calculation encompasses two models for evaluating cooling load in TRNSYS: energy rate control and temperature level control. Comparison of the total cooling loads obtained from different sets of experimental data enables to validate the measurements. The experimental result shows that the latent load is fairly large even in the absence of apparent air change in the space, which needs to be clarified. Each of hourly and daily accumulated sensible loads is compared between the experiment and two calculation models. Despite an inconsistency associated with solar irradiation, both of the models agree favorably with the experiment within a tolerance, illustrating their capability of properly predicting space thermal loads.

• Korean Journal of Remote Sensing
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• v.26 no.6
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• pp.675-680
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• 2010

Temperature is one of the main issues in climate change, and the urban heat island effect in highly developed urban areas is an important issue that we need to deal with. This study analyzed the extent of the cooling effects of urban green spaces. The study used a surface temperature map of Seoul. It found that the cooling effects of green space was observed within limited distances, although it varied a little depending on the parks investigated. The cooling effect distance ranged from 240m to 360m, averaging about 300m. It also found the size of an urban green space does not make much difference in cooling the surrounding areas. Although further investigation with diverse urban areas should be conducted on this matter, the results did imply that many small green spaces in the neighborhood are more effective than a single big green space in mitigating the heat island effects of cities.

• 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 the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.111-117
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• 2004

An analytical study was carried out to evaluate the regenerative cooling characteristics in the liquid rocket engine of a 10tf-thrust level using kerosene as a fuel. As a supplementary cooling method, a radiative cooling was applied to the nozzle extension. It was found out from this work that the cooling system with the regenerative and radiation cooling only is not adaptable for the liquid rocket engine of a 10tf-thrust level using kerosene as a fuel for the $2^{nd}$ stage of the space launch vehicle, with the viewpoint of the thermal and thermo-structural instability and the excessive pressure drop in the cooling channel.

• Journal of Environmental Impact Assessment
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• v.32 no.3
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• pp.176-186
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• 2023

Urban Heat Island (UHI) is caused by an energy imbalance in urban areas, where building design and land cover contribute to its amplification. To mitigate UHI, increasing green space is one of the well known and the most effective approach. This study aims aimed to identify specific components of green spaces that lower temperatures and demonstrate the cooling effects based on their size and composition. Forests within green spaces have had a greater impact on temperature reduction due to shading and blocking solar radiation. Although lakes also contributed to temperature reduction, the effect to cooling intensity was not significant. The cooling distance does not depended on green space size or composition. The study emphasizes that initial temperature has a strongerinfluence on cooling intensity than green space size, highlighting the importance of vegetation type within green spaces to achieve a cooling effect. These findings provide valuable insights for urban planning and the design of green spaces to mitigate the effects of the urban heat island.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.2
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• pp.86-96
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• 2010

The paper describes development and evaluation of a simple method for determining gradient of modified linear setpoint variation to reduce peak electrical cooling demand in buildings using building precooling and setpoint adjustment. The method is an approximated approach for minimizing electrical cooling demand during occupied period in buildings and involves modified linear adjustment of cooling setpoint temperature between $26^{\circ}C$ and $28^{\circ}C$. The gradient of linear variation or final time of linear increase is determined based on the cooling load shape in conventional cooling control having a constant setpoint temperature. The potential to reduce peak cooling demand using the simple method was evaluated through building simulation for a calibrated office building model considering four different weather conditions. The simple method showed about 30% and 20% in terms of reducing peak cooling demand and chiller power consumption, respectively, compared to the conventional control.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.756-762
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• 2011

A gas deflector cooling system plays an important role in the suppression of shock wave generated during the ignition of a launch vehicle engine. Also, this system decrease a large vibration of damaging the payload and structure of the launch vehicle. The gas deflector cooling system in the launch pad of NARO space center was constructed to directly inject water into the plume of the launch vehicle engine. The flight test result of NARO space launch vehicle showed that this method had a good performance on the viewpoint of cooling the gas deflector.