• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.1
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• pp.80-86
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• 2011

Vertical open display cabinets are widely used in shopping mall, supermarkets, retail stores. Maintaining the temperature of foods in the display cabinet is vitally important to retailers to ensure optimal food quality and safety. The purpose of this study is to reduce the infiltration of air and heat loss from ambient space to display cabinet. The three-dimensional Computational Fluid Dynamics(CFD) simulation is used for the analysis of air flow patterns and temperature distribution in refrigerated display cabinets. Under several operating conditions which vary both the inner and outer jet velocities in the range from 0.3 to 1.1 m/s, simulations were carried out. This paper presents a performance of display cabinets with single jet and double jet. The energy consumption due to thermal entrainment ratio is plotted with varying Re. It was found that the double jet system is better than single jet system in terms of temperature distribution and energy saving.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.32-35
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• 2006

The validation of a groundwater source heat pump system installation site is estimated by bydrogeothermic model ing. The hydraulic characteristics of the aquifer system is evaluated from pumping and recovery tests. In addition, the temperature distribution by the pumping and the injection of groundwater, and water level fluctuations are simulated by numerical modeling. The total cooling and heating load for the building is designed as 120RT(refrigeration ton) and the ground water source heat pump system covers 50RT as a subsidiary system The scenario of heat pump operation is organized as pumping and inject ion of groundwater that is performed for 8 hours per day in cooling mode for 90 days during the summer season The heat transfer by the injected warm water is limited near the inject ion wells in the simulated temperature distribution. The reason is that the given operation time is too short to expect broad thermal diffusion in large volume of the aquifer in the simulation time The simulated groundwater level and temperature distribution can be used as important data to develope an energy effective pumping and injection well system. Also it will be very useful to evaluate the hydraulic capacity of a target groundwater reservoir.

• KIEAE Journal
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• v.15 no.4
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• pp.105-110
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• 2015

Purpose: This study aimed at finding the optimal input variables of the artificial neural network-based predictive model for the optimal controls of the indoor temperature environment. By applying the optimal input variables to the predictive model, the required time for restoring the current indoor temperature during the setback period to the normal setpoint temperature can be more precisely calculated for the cooling season. The precise prediction results will support the advanced operation of the cooling system to condition the indoor temperature comfortably in a more energy-efficient manner. Method: Two major steps employing the numerical computer simulation method were conducted for developing an ANN model and finding the optimal input variables. In the first process, the initial ANN model was intuitively determined to have input neurons that seemed to have a relationship with the output neuron. The second process was conducted for finding the statistical relationship between the initial input variables and output variable. Result: Based on the statistical analysis, the optimal input variables were determined.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1209-1214
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• 2009

Various automatic temperature control systems have been used widely in Korea for the conservation of heating energy and the enhancement of thermal comfort in residential buildings. But the heating control performance for automatic temperature control systems extensively vary with the design and operational conditions of the heating system, the climate condition and others. It was introduced in this study a numerical calculation program package to analyze heating control characteristics of the automatic temperature control system. This package is able to analyze the room air temperature, return water temperature, supplied heating flux and flow rate, and so on. One the other hand, the simulation results were verified by comparing with the field test results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.392-397
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• 2013

To fulfill the demands concerning energy efficiency for zero energy buildings, various technologies of architects and engineers are required. This study aims to estimate the thermal performance of heat source equipment in which part load characteristics are considered in an office building. Overestimation of heat source equipment was reviewed through literature survey, and heating and cooling loads depending on the capacity and division of the equipment were analyzed through a simulation program (DOE-2.1E). The conclusions gained from this study are as follows; 1) The more the division of equipment, the less the heating and cooling energy consumption. 2) When a large item of equipment is divided into two small items of equipment, the optimum application rate showed as 5:5 for chiller, and 7:3 for boiler, respectively.

• Advances in concrete construction
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• v.9 no.5
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• pp.459-467
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• 2020

Mechanical and thermal properties of composite sandwich wall panels are affected by changes in their external environment. Humidity and temperature changes induce stress on wall panels and their core connectors. Under the action of ambient temperature, temperature on the outer layer of the wall panel changes greatly, while that on the inner layer only changes slightly. As a result, stress concentration exists at the intersection of the connector and the wall blade. In this paper, temperature field and stress field distribution of UHPC-RW-RC (Ultra-High Performance Concrete - Rock Wool - Reinforced Concrete) wall panel under high temperature-sprinkling and heating-freezing conditions were investigated by using the general finite element software ABAQUS. Additionally, design of the connection between the wall panel and the main structure is proposed. Findings may serve as a scientific reference for design of high performance composite sandwich wall panels.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.199-205
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• 2014

The integration of FC (Fuel Cell) and GSHP (Ground Source Heat Pump) hybrid system could produce a synergistic advantage in thermal and electric way. This study intends to analyse the economical aspect of a FC integrated GSHP hybrid system compared to the conventional system which is consisted with a boiler and a chiller. Based on the hourly simulation, the study indicated that GSHP system and FC+GSHP hybrid system could reduce the energy consumption on a building. The method of the economic assessment has been based on IEA ECBCS Annex 54 Subtask C SPB(Simple Payback) method. The SPB was calculated using the economic balanced year of the alternative system over the conventional (reference) system. The SPB of the alternative systems (GSHP and FC+GSHP) with 50% initial incentive was 4.06 and 26.73 year respectively while the SPB without initial incentive of systems was 10.71 and 57.76 year.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.693-699
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• 2013

This paper describes a method for size optimization of the major design variables for solar water heating systems at the stage of concept design. The widely used RETScreen simulation tool was used for optimization. Currently, the RETScreen tool itself does not provide a function for optimization of the design parameters. In this study, an optimizer was combined with the software. A comparative study was performed to evaluate the RETScreen-based approach with the case study of a solar heating system in an office building. The optimized results using the RETScreen model were compared to previously published results with the TRNSYS model. The objective function of the optimization is the life-cycle cost of the system. The optimized design results from the RETScreen model showed good agreement with the optimized TRNSYS results for the solar collector area and storage volume, but presented a slight difference for the collector slope angle in terms of the converged direction of the solutions. The energy cost, life-cycle cost, and thermal performance regarding collector efficiency, system efficiency, and solar fraction were compared as well, and the RETScreen model showed good agreement with the TRNSYS model for the conditions of the base case and optimized design.

• 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.

• Journal of the Korean Solar Energy Society
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• v.28 no.2
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• pp.50-57
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• 2008

This study intends to evaluate the effect on indoor environment(annual thermal load, sunshine)by the application of the movable horizontal shading device on summer and winter season. For these purpose, we supposed the models which are composed of the several horizontal shading devices. Then we analyzed the simulation using the IES5.5.1 and Seoul weather data. The results of this study are as follows: 1) The proper length, angle of horizontal shading device is 2.1m, 28 degree, respectively. 2) The decreasing rate of the annual load of the Movable Horizontal Shading Model(MHSM) in comparison with the No Shading Model(NSM) & Conventional Horizontal Shading Model(CHSM) is 31.11%, 6.63% respectively. 3) The decrease of sunshine of the MHSM on summer season is effective the alleviation of visual displeasure. On the other hand, the increase of sunshine of the MHSM on winter season is effective the psychological comfort. Further study is to be required the sensitivity analysis on the various shading length for the realistic proper shading length.