• KIEAE Journal
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• v.17 no.3
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• pp.99-106
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• 2017

Purpose: Most modern office buildings adopt the curtain wall system in order to provide occupants with the sense of openness and high-technology, which requires large window area. As a result, the amount of solar radiation increases, negatively affecting cooling load during the summer and increasing energy costs. However, the performance of window itself is not sufficiently controllable parameter to control thermal comfort and solar radiation. Therefore, a shading device such as venetian blind is required to control them and thus a variety of studies have been performed thus far. So, the purpose of this study is to improve the performance of blind through the development of blind control algorithm. Method: Among various input variables for the control of venetian blinds, the vertical solar radiation has been selected in this study as the primary input variable and the optimal control algorithm for venetian blinds were developed for each window orientation. Result: The developed optimal control algorithm has a positive effect on building energy savings.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.364-371
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• 2005

Fuel cell systems(FCS) have a financial and environmental advantage by providing electricity at a high efficiency and useful heat. For use in a residence, a polymer electrolyte fuel cell system(PEFCS) with a battery pack and a hot water storage tank has been modelled and simulated. The system is operated without connection to grid line. Its electric conversion efficiency and heat recovery performance are highly dependent on operation strategies and also on the seasonal thermal and electric load pattern. The output of the fuel cell is controlled stepwise as a function of the state of the battery and/or the storage water tank. In this study various operation strategies for cogeneration fuel cell systems are investigated. Average fuel saving rates at different seasons are calculated to find proper load management strategy. The scheme can be used to determine the optimal operating strategies of PEFCS for residential and building applications.

• Journal of the Korean Solar Energy Society
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• v.27 no.1
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• pp.83-90
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• 2007

Apartment balcony has been indiscreetly remodeled since the government permitted remodeling on January 2006. But remodeled balcony has a few problems such as increase of heating energy, surface condensation and cold draft. The reason of thermal problem is mainly caused by the window system in a extended balcony. The purpose of this study is to analyze heating and cooling energy and propose the efficient window types for the extended balcony area of a apartment building. 4 types of window system which have fairly high U value in Korea are investigated as follows ; double clear glass, double low-e glass, triple clear glass and triple low-e glass. Comparing double clear 91ass with double low-e glass, triple clear glass and triple low-e glass, simulation results show that 10%, 7% and 15% saving of total primary energy can be expected.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.826-831
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• 2006

In this paper, we discussed the energy performance of underfloor air distribution(UFAD) and overhead air distribution system according to outdoor air intake rates in a office building. For this, the laboratory(S lab.) is selected for measuring the thermal environments of UFAD system and overhead system. Based on the measured data, the TRNSYS simulation is used to evaluate the energy performance of UFAD system and the overhead system according to outdoor air intake rates. By increasing outdoor air intake rates from required outdoor air intake rates(100CMH) to maximum air intake rates, the energy savings of UFAD system comparing with overhead system are varied $15%{\sim}25.6%$ in summer, $12.8%{\sim}19%$ in fall/spring and not varied in winter(8%). As results of simulations on stratification height and cooling set temperature, the lower the stratification height and the higher cooling set temperature, the larger cooling energy savings of UFAD comparing with overhead system according to outdoor air intake rates.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.795-800
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• 2006

A common approach to achieve better thermal comfort with hydronic radiant floor heating system is supply water temperature control. This is the control method through which supply water temperature is varied with outdoor temperature. In this study, a comprehensive, yet simple calculation method to find optimum supply water temperature is evaluated by combining heat loss from the building and heat emission from the hydronic radiant floor heating system. And then the control performance of suggested calculation method is confirmed through experiment. It is shown that indoor air temperature is stably maintained around the set point.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.12
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• pp.73-82
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• 2018

The objective of this study was to evaluate particle collection performance of electrostatic precipitator (ESP) integrated with double skin façade in naturally ventilated residential buildings using numerical method. To evaluate the efficiency, computational fluid dynamics (CFD) simulation based on electric potential and Lagrangian method was applied. The CFD model was validated by comparing the simulated results with the experimental data including thermal characteristic of double skin façade (DSF) and particle removal characteristic of electrostatic precipitator. The validation results showed that the root mean square error (RMSE) between predicted values and measured values of velocity and temperature in intermediate space of DSF was 1.2%. The adequacy of ion space charge density and turbulent model were determined. The RMSE between predicted values and measured values of collection efficiency of ESP was 9.2%. In addition, the case study was performed to present the application of the numerical method based on validation results of ESP integrated with façade.

• International Journal of High-Rise Buildings
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• v.13 no.1
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• pp.85-95
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• 2024

A composite member made of concrete-filled steel tubes (CFT columns) has been recognized for its fire resistance due to the thermal mass effect of concrete inside the steel tube, as shown in various studies. In this study, the fire resistance performance of reinforced CFT columns under constant axial load was evaluated using finite element analysis with ABAQUS. For this purpose, the variables including cross-section size, steel tube thickness, and concrete cover thickness were set, and the temperature distribution in the column cross-section exposed to a standard fire was investigated using heat transfer analysis. Ultimately, a P-M interaction curve was obtained by evaluating the overall residual strength of columns, and the fire resistance time was determined by evaluating axial displacement-time responses due to the reduction in load capacity during fire through stress analysis.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.197-204
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• 2016

Concrete walls of neutron generating facilities such as fusion reactors and fission reactors become radioactive by neutron irradiation. Both low-activation and neutron shielding are a critical concern at the dismantling stage after the shutdown of facilities with a requirement of radioactive waste management. To tackle this, two types of additives were investigated in fabricating mortar specimens: synthetic high polymers and boron carbide. It is well known that a hydrogen atom is effective in neutron shielding by an elastic scattering because its mass is almost the same as that of the neutron. And boron is an effective neutron absorber with a big neutron absorption cross section. In this study, the effect of the type, shape, and size of polymers were investigated as well as that of boron carbide. Total 16 mix designs were prepared to reveal the effect of polymers on mechanical properties and neutron shielding performance. The neutron does equivalent of polymers-based mortar for fast neutrons decreased by 36 %, and the count rate of boron carbide-based mortar with regard to thermal neutrons decreased by 90 % compared to conventional mortar. These results showed that a combination of polymers and boron carbide compounds has potential to reduce the thickness of neutron shields as well as radioactive waste from reactors.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.96-108
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• 2015

A passive containment cooling system has been designed to remove the heat inside a containment during accidents without external power supply. In this work, the PCCS was introduced in the APR1400 plant to replace the containment spray system and, then, the thermal-hydraulic performance of the PCCS was analyzed using the system thermal-hydraulic computer code, MARS. A double-ended cold-leg break accident, which is known to induce the maximum pressure in the containment, is simulated, where the thermal hydraulics of the PCCS, the reactor coolant system, and the containment are simultaneously simulated. The results of the calculations showed that the PCCS can replace the existing spray system and that the containment building and its internal structure also play a very important role for the heat removal during the accident. Some sensitivity calculations were carried out to evaluate the model uncertainty and the effects of design parameters. The limitations of the PCCS are also discussed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.276-284
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• 2022

In this study, performance evaluation and rheological characteristics were analyzed for recycling the fine powder of nuclear power plant dismantled waste concrete as a solidifying agent for radioactive waste disposal. The radioactive concrete fine powder was used to prepare a simulated sample, and the test specimen was prepared using Di-water, CoCl₂, and 1 mol CsCl aqueous solution as mixing water. Regardless of the aggregate mixing ratio and the type of mixing water, it satisfies the performance standard of 3.45 MPa for compressive strength at 28 days of age. All specimens satisfied the criteria for submersion strength, and the thermal cycle compressive strength satisfies the criteria for all specimens except Plain-50. As a result of evaluating the rheological properties of the solidifying agent, it was found that the increase in the aggregate mixing rate decreased the yield stress and plastic viscosity. The leaching index for cobalt and cesium of all specimens was 6 or higher, which satisfies the standard. In order to secure the stable performance of the solidifying agent, it is considered effective to use 40 % or less of the aggregate component in the solidifying agent.