• KIEAE Journal
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• 제12권2호
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• pp.111-116
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• 2012

Faced with the international issue of environmental problems from global warming and energy consumption, the Korean Government has made many efforts on reducing energy and $CO_2$ emission under the motto of "Low-Carbon Green Growth". In order to reduce energy in the building sector, severe design standards and regulations on saving energy in new buildings have been established. Now, it is necessary to focus on deteriorated buildings where applications of energy saving designs and techniques have been insufficient, for maximizing energy saving in the building sector. Specially, it is very important to reduce energy through the remodeling process at deteriorated school buildings which were built over 20 years ago and sharply changed into the excessive energy consumption structure from new educational curricula. Thus, this paper examined the effects of potential factors to reduce energy at deteriorated elementary school buildings using the energy simulation on the Visual DOE 4.0 program. Among applied factors of insulations, southern louver, window's SHGC, indoor setup temperature, and system efficiency, all factors except window's SHGC turned out contribute to reduce energy at the deteriorated elementary school buildings, compared with the baseline energy performance.

• KIEAE Journal
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• 제13권5호
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• pp.97-102
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• 2013

Many countries over the world have acknowledged the global warming problem by greenhouse gas emission and tried to solve the problem. The Korean government has also taken many actions such as The Act on Low Carbon, Green Growth and on Promoting Green Building in that architectural building section takes 1/4 of national greenhouse gas emission. Under the situation that buildings constructed 15 years ago when insulation standards were reinforced take about 74%, The Plan on Vitalizing Green Remodeling, finally established on July 2013, will induce energy-efficient remodeling of deteriorated buildings. Using the energy simulation by the Visual DOE 4.0 program, this paper proposed the ways of energy-efficient remodeling of deteriorated high school buildings by measuring energy saving performance of factors that were drawn from the previous study. The factors considered are insulation, window's SHGC, south louver, system efficiency, and indoor setting temperature. Among them, all factors except SHGC proved contribution to reducing energy use at deteriorated high school buildings, compared with the baseline energy consumption.

• Wind and Structures
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• 제11권6호
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• pp.479-496
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• 2008

In this paper, computer simulation of wind flow around a single cooling tower with louver support at the base in the KAZERUN power station in south part of IRAN is presented as a case study. ANSYS FLOTRAN, an unstructured finite element incompressible flow solver, is used for numerical investigation of wind induced pressure load on a single cooling tower. Since the effects of the wind ribs on external surface of the cooling tower shell which plays important role in formation of turbulent flow field, an innovative relation is introduced for modeling the effects of wind ribs on computation of wind pressure on cooling tower's shell. The introduced relation which follows the concept of equivalent sand roughness for the wall function is used in conjunction with two equations ${\kappa}-{\varepsilon}$ turbulent model. In this work, the effects of variation in the height/spacing ratio of external wind ribs are numerically investigated. Conclusions are made by comparison between computed pressure loads on external surface of cooling tower and the VGB (German guideline for cooling tower design) suggestions.

• 한국산업보건학회지
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• 제15권3호
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• pp.239-249
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• 2005

Ventilation effect is analyzed for boiler building with multiple heat sources. Air flow inside the boiler building is characterized as turbulent mixed convection. Analysis methodology is set up with two different $k-{\varepsilon}$ type models (standard $k-{\varepsilon}$, RNG $k-{\varepsilon}$). Two different cases with high and low outside temperature are analyzed. In case of high outside temperature condition, mixed convection is well realized inside the boiler building. With different upper louver opening rate, air flow is also well established and proper opening rate is found to meet design limit in case of low outside temperature condition. Difference of analysis results for two different turbulence models are not significant. Therefore, analysis methodology with simple $k-{\varepsilon}$ turbulence model is found to be reliable for the boiler building ventilation analysis. However, more simplified geometrical model is desired to expand its application.

• 한국산업보건학회지
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• 제26권3호
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• pp.342-349
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• 2016

Objectives: The objective of this paper is to find flow and heat transfer characteristics numerically in boiler buildings for three different ventilation window configurations. Methods: Turbulent natural convection flow in boiler buildings with a constant heating wall temperature was analyzed numerically. Governing equations were solved with standard finite-volume method using the SIMPLE algorithm. Conclusions: Flow and heat transfer characteristics are found for three different ventilation types. In the lower area under furnace, velocity and temperature distributions show similar patterns among the three different ventilation types. In the upper area over furnace, however, air flow is well mixed with lower peak temperatures for types B and C, which have roof ventilation windows, compared to type A which has side wall louvers only. Also, type B, with a single large roof window, shows better ventilation effect than does type C with its distribution roof windows.

• 설비공학논문집
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• 제22권10호
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• pp.710-718
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• 2010

A numerical study was performed to predict refrigerant charge amount in a mini-channel condenser for a R410A residential air-conditioning system. Multi-channel flat tubes with 12 mini-channels of 1.17 mm average hydraulic diameter for each tube were applied to the condenser. The condenser consisted of 3 passes, and the first, second, and third pass had 44, 19, and 11 tubes, respectively. Each pass was connected by a vertical header. In this study, the condenser was divided into 410 finite volumes, and analyzed by an $\varepsilon$-NTU method. With thermophysical properties and void fraction models for each volume element, the R410A amount distribution and a total charge amount in the condenser were calculated. The predicted total charge amount was compared with the experimentally measured charge amount under a standard ARI A condition. The developed model could predict the charge amount in the mini-channel condenser within prediction errors from -23.9% to -3.0%. Air velocity distribution at the condenser face was considered as non-uniform and uniform by the simulation model, and its results showed that the air velocity distribution could significantly influence the charge amount and vapor phase distribution in the condenser.

• 설비공학논문집
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• 제8권1호
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• pp.166-175
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• 1996

In recent years, air-conditioning units designed with higher efficiency and more compactness are required due to emphasis on energy efficiency in home electrical appliances. This trend in the air-conditioning industries has accelerated the development of improved heat exchanger with a better performance in heat transfer aspects. In this study, experiments were performed to investigate the shape and configuration of fins affecting on the performance of the conventional fin-and-tube type heat exchanger equipped in a commercial air conditioners. The geometry similtude method was employed to measure the heat transfer coefficient and pressure drop. Experimental results show that this method is very useful to analyze the heat transfer characteristics of the fin-and-tube type heat exchanger. It is also found that the slit fin has better performance than the conventional fin type in the air conditioners. The present results indicate that heat transfer from the fin si influenced by the parameters such as the forming area of the slit fin, the type of interrupted surfaces like a louver or slit, slit patterns and slit raised direction, and it also affects the overall heat exchanger performance.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권2호
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• pp.49-56
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• 2006

Heat transfer performances of individual row of two-row fin and tube heat exchangers are experimentally investigated. Tested are four heat exchangers which are geometrically identical with the exception of fin shape, slit or louver, and that the fins between the first row and the second row are connected or separated. The tube diameter and fin spacing of the heat exchangers examined are 7mm and 1.4mm, respectively. All thermal fluid measurements are made using a psychrometric calorimeter. In order to evaluate air-side heat transfer coefficients of individual rows, tube-side water flow rates of individual rows are independently controlled such that the water-side temperature drops in each row remain at $5^{\circ}C$. Frontal air velocity varies in the range from 0.7m/s to 2.5m/s. Heat transfer coefficients are presented in terms of Colburn ${\jmath}-factor$. The results show that the heat transfer coefficient of the upstream row is larger than that for the downstream row at low Reynolds numbers.

• 한국실내디자인학회논문집
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• 제14권3호
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• pp.139-146
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• 2005

This paper focuses on the response of architectural form to the technological characteristics in the institute facilities. For this, we study the meaning of technology in the aspect of physical, formal and social concepts and their architectural expression and sort by grouping through analyzing 27 cases of foreign current Institute facilities. Conclusions can be summarized as followings: 1) Vocabulary of technology in physical concept is presented by the environmental control through the experimental surface such as louver and glazing and the independent exposed equipment. 2) Vocabulary of technology in physical concept is presented using the machine like aesthetics by exposing the structural members and designing the exterior form using dynamical images. 3) The expression of social meaning in technology is presented by standardization, parts assembling through mass production system, the unit material for expression of today's industrial society. The expressions of technological language in the institute facilities are used not only one vocabulary but comprehensive ones.

• 설비공학논문집
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• 제10권3호
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• pp.315-323
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• 1998

This paper contains a verification of simulation program to predict the capacity of a condenser used in car air-conditioners. Verification of simulation program is carried out with the comparison error between experiment and simulation bounds within 3.5%. The present investigation shows the results for heat transfer rates of condenser under different operating conditions, such as velocity and degree of superheat. The range of front velocity of air is 1∼5m/s. As the front velocity is increased, the heat transfer rate of condenser is largely increased at a low velocity range. In a meanwhile, heat transfer rate of condenser is almost constant in a range of velocity over 3m/s. As for the effect of inlet pressure of refrigerant on the heat transfer rate, we obtained the similar trend of heat transfer rates as like varying the front velocity, Also we have calculated the heat transfer rates with varying inlet superheats of refrigerant, the larger the superheat is, the more heat transfer rate is obtained.