• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.6 no.2
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• pp.1-7
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• 2010

The objective of this study is to find the optimal control algorithm of a hybrid Plant, which is combined by renewable energy plant of the GSHP(Geothermal Source Heat Pump) and the normal plant (Chiller, boiler). The work presented in this study was carried out in the EnergyPlus(Version 2.0). The EnergyPlus was modified in order to simulate the hybrid plant. The plant system was controlled by the load-range-based operation in which schemes select a user specified set of equipment for each user specified range of a particular simulation condition. In the use of the load-range-based operation, four kind of control cases were defined and simulated in order to obtain the optimal control algorithm of the hybrid plant. The result showed that the Case 2 was the optimal control algorithm which used the GSHP as a base operating plant and the normal plant as an assistant operating plant. Even though the normal plant was operated in full load and the renewable energy plant of the GSHP was operated in partial load, the annual energy consumption of the normal plant was larger than that of the GSHP plant.

• Advances in aircraft and spacecraft science
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• v.9 no.1
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• pp.59-68
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• 2022

The physical and mathematical foundations of the heat-shielding composite materials functioning under the conditions of aerodynamic heating of aircraft, as well as under the conditions of the point effect of high-energy radiation are considered. The problem of deformation of a thin shallow shell under the action of a local temperature field is approximately solved. Such problems arise, for example, in the case of local destruction of heat-protective coatings of aircraft shells. Then the aerodynamic heating acts directly on the load-bearing shell of the structure. Its destruction inevitably leads to the death of the entire aircraft. A methodology has been developed for the numerical solution of the entire complex problem on the basis of economical absolutely stable numerical methods. Multiple results of numerical simulation of the thermal state of the locally heated shallow shell under conditions of its thermal destruction at high temperatures have been obtained.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.11
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• pp.972-980
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• 2002

This work is aimed at estimating the effects of various factors on the energy consumption of Korean-style apartment houses using TRNSYS. The factors considered here include the nominal size of floor area, type of remodeling, azimuth, sidewall insulation, and window type. Based on some assumptions, an actual apartment house is simplified into a model that is used for thermal load calculations. The simplified model is validated by showing a good agreement with the actual one in the predicted result. Remodeling balconies into unconditioned buffer spaces yields a favorable thermal performance in comparison with the original type regardless of the nominal size. Incorporating balconies into a conditioned indoor space leads to sharp increases in thermal loads, which must be avoided in view of energy conservation as well as structural problem. A quantitative assessment on the azimuthal effect indicates that the heating energy can be saved up to 16％ by taking the south or southeast direction. Reduction in the heating load with enhancing the sidewall insulation is gradual, so that a cost-effectiveness analysis may be needed when amending the regulations concerned. Glazing appears to significantly affect the heat transfer through window. A typical case illustrates that the heating load is decreased about 25％ by simply adopting triple glazing instead of double glazing.

• Journal of the Korean Solar Energy Society
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• v.38 no.5
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• pp.37-47
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• 2018

The heating performance of a solar thermal seasonal storage system applied to a glass greenhouse was analyzed numerically. For this study, the gardening 16th zucchini greenhouse of Jeollanam-do agricultural research & extension services was selected. And, the heating load of the glass greenhouse selected was 576 GJ. BTES (Borehole Thermal Energy Storage) was considered as a seasonal storage, which is relatively economical. The TRNSYS was used to predict and analyze the dynamic performance of the solar thermal system. Numerical simulation was performed by modeling the solar thermal seasonal storage system consisting of flat plate solar collector, BTES system, short-term storage tank, boiler, heat exchanger, pump, controller. As a result of the analysis, the energy of 928 GJ from the flat plate solar collector was stored into BTES system and 393 GJ of energy from BTES system was extracted during heating period, so that it was confirmed that the thermal efficiency of BTES system was 42% in 5th year. Also since the heat supplied from the auxiliary boiler was 87 GJ in 5th year, the total annual heating demand was confirmed to be mostly satisfied by the proposed system.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.8 no.4
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• pp.221-236
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• 1979

The three years Performance of a liquid type solar heating system has been determined for a system which has been determined for a system which has been operating continuously since 1976 in Seoul with no serious maintenance. A flat plate collector is used to transform incident solar radiation into thermal energy. This energy is stored if the form of sensible energy and used as needed to supply the space heating loads. An electric auxiliary heaters are provided to supply energy for space heating load when the energy in the storage tank is depleted. The ratio of useful collected solar heat divided by the total solar radiation on the collector was obtained about 84 per cent. It is also obtained the relation between ratio of solar collector area to the heating area and the ratio of useful collected solar energy to the heating load for the useful design data. A comparison between the measured and simulated results with the solar space heating system is described. Hour by hour simulation is made on unsteady state basis using the system parameters and meteorological data at the experiment site. The result of comparison turned out satisfactory for the solar heating system, though the simulation was formed somewhat higher than by experimental.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.83-88
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• 2001

This paper presents modelling and analyzing method of centrifugal chiller which has a rated capacity of 200 RT(703 kW) through on-site performance test. Field data of chiller installed in the clean-room building of KIST have been collected, Simple models were developed for predicting the heat exchangers and system performances by regression of chiller operation data during 5 days in August. The models proposed here account for the effect of variations of cooling capacity, temperatures and flow rates of secondary fluids. The models are consistent with real performance data from June to September within ${\pm}5%$ error. The COP of centrifugal chiller are estimated under the standard rating conditions and reduced mass flow rate of chilled and cooling water.

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.67-75
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• 2007

This study intends to the adequacy inspection of the room temperature variation rate that is available in the building heat performance evaluation index, so we performed the sensitivity analysis about the room temperature variation rate and the energy consumption in the room. For these purpose, we supposed the models which are composed of the various window area, insulation thickness and ventilation rate. Then we analyzed the simulation using the ESP-r and Seoul weather data. In this research, the pattern of the increasing & decreasing rate of annual load according to the change of the various design factors is similar to the pattern of increasing & decreasing rate of not the K-values but the room temperature variation rate. Also we derive the optimum value of the various design factors and the room temperature variation rate in this analysis model. Further study is to be required the development of convenient tool to use in the real design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.346-351
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• 2003

This paper aims at suggesting design guidelines for a perimeter-less HVAC system that contributes energy savings. Perimeter-less HVAC system is one that relieves difficulties fuck as handling mixing loss, uneven radiative environment, and maintenance and repair. It prevents heat load gained through window and outdoor wall without modifying a previously equipped building skin system. In this paper, we performed several kinds of CFD (computational fluid dynamics) cases through numerical simulation to obtain an optimized perimeter-less design, and then we conducted a large-scale model experiment to see how the push-pull air flow would handle indoor heat to obtain an optimized perimeter-less design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.879-885
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• 2000

It is a serious subject for energy conservation to prevent the energy loss caused by mixing of heated and cooled air jets in a building which two types of air-conditioning systems are adopted in perimeter and interior zone. The purpose of this paper is to clarify the quantitative and qualitative mechanisms of the mixing loss and to propose preventive methods for it. In this paper, by using the dynamic heat load calculation method, heat extraction loads of a typical office building in Pusan are calculated. According to the results, numerical simulation based on the computational fluid dynamics were peformed in order to measure the mixing loss in physical size HVAC system. Then, the distributions of air temperature and velocity are analyzed in order to grasp the relations by setting temperature differences influence on the mixing loss.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.970-978
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• 2003

This paper aims at suggesting design guidelines for a perimeter-less HVAC system that contributes energy savings. Perimeter-less HVAC system is one that relieves difficulties such as handling mixing loss, uneven radiative environment, and maintenance and repair. It prevents heat load gained through window and outdoor wall without modifying a previously equipped building skin system. In this paper, we conducted a large-scale model experiment to see how the push-pull air flow would handle indoor heat to obtain an optimized perimeter-less design, and then we plan to perform several kinds of CFD (computational fluid dynamics) cases through numerical simulation