• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.871-879
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• 1999

Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectrums of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared of the experimental rig with and without the bounding fence for various flow rates.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.947-955
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• 2005

For the purpose of evaluating the thermal performance for air-barrier air conditioning system in perimeter zone, two air-conditioning systems, conventional perimeter air-conditioning system and air-barrier system, are evaluated and compared by scale model experiment and simulation during cooling season. As a result, measurement shows that supply air velocity of 1 m/s in the upstream direction at perimeter is more effective. Air-barrier system could reduce the cooling energy by $10\sim20\%$ compared with conventional system. Numerical simulation was carried out considering solar effect for reliable result. This method has improved the accuracy of numerical simulation for the space affected by the solar radiation. Both measurement and simulation results show that supply air velocity of 1 m/s at perimeter is the most effective.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.3
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• pp.433-442
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• 2013

This study aimed to compare the dynamics of air temperature and velocity under two different ventilation and housing systems during summer and winter in Korea. The $NH_3$ concentration of both housing systems was also investigated in relation to the pig's growth. The ventilation systems used were; negative pressure type for the enclosed pig house (EPH) and natural airflow for the conventional pig house (CPH). Against a highly fluctuating outdoor temperature, the EPH was able to maintain a stable temperature at 24.8 to $29.1^{\circ}C$ during summer and 17.9 to $23.1^{\circ}C$ during winter whilst the CPH had a wider temperature variance during summer at 24.7 to $32.3^{\circ}C$. However, the temperature fluctuation of the CPH during winter was almost the same with that of EPH at 14.5 to $18.2^{\circ}C$. The NH3 levels in the CPH ranged from 9.31 to 16.9 mg/L during summer and 5.1 to 19.7 mg/L during winter whilst that of the EPH pig house was 7.9 to 16.1 mg/L and 3.7 to 9.6 mg/L during summer and winter, respectively. These values were less than the critical ammonia level for pigs with the EPH maintaining a lower level than the CPH in both winter and summer. The air velocity at pig nose level in the EPH during summer was 0.23 m/s, enough to provide comfort because of the unique design of the inlet feature. However, no air movement was observed in almost all the lower portions of the CPH during winter because of the absence of an inlet feature. There was a significant improvement in weight gain and feed intake of pigs reared in the EPH compared to the CPH (p<0.05). These findings proved that despite the difference in the housing systems, a stable indoor temperature was necessary to minimize the impact of an avoidable and highly fluctuating outdoor temperature. The EPH consistently maintained an effective indoor airspeed irrespective of season; however the CPH had defective and stagnant air at pig nose level during winter. Characteristics of airflow direction and pattern were consistent relative to housing system during both summer and winter but not of airspeed. The ideal air velocity measurement favored the EPH and therefore can be appropriate for the Korean environment. Further emphasis on its cost effectiveness will be the subject of future investigations.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.633-635
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• 2010

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.5
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• pp.304-313
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• 2008

This paper investigates the indoor-air-quality (IAQ) characteristics of the interior space equipped with system air-conditioner. The behaviors of individual variables such as temperature, humidity and concentration of carbon dioxide ($CO_2$) that influence on IAQ of the interior space were characterized under various cooling conditions by numerical and experimental studies. The numerical analysis predicting the temperature behavior of the interior space was conducted, and its results showed a good agreement with the experimental ones. The $CO_2$ concentration and humidity were measured and their time dependent behaviors were monitored and analyzed. From the results, it was found that there existed the differences of the time-dependent behaviors of IAQ variables according to the locations. In addition, it is demonstrated that the large discharge angle of $45^{\circ}$ made the temperature profile more irregular and the high discharge flow of 5.34 m/s produced similar temperature profiles at three different sensing locations. Finally, the humidity of interior space was less sensitive to the changes of the air cooling conditions than the case of temperature and the $CO_2$ concentration increase mainly depended on the number of individuals inside the space.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.508-516
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• 2010

An efficient code has been developed to predict dispersion of indoor air pollutants The computing capability of the code has been compared with that of a commercial code inn a benchmark test. After that, the code has been employed to compute dispersion of a pollutant released from a new furniture, a kind of Sick Building Syndrome (SBS). A sofa which generates formaldehyde is implemented by using an immersed boundary method. Large Eddy Simulation (LES) is employed to obtain time-dependent velocity and scalar fields. LES has bee regarded as an academic tool, but the newly-developed code reveals a possibility of application of LES to practical problems, especially dispersion of indoor pollutants.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.448-453
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• 2006

Electrical resistivity is an important property for the collection efficiency in the electrostatic precipitator. In this paper, electrical resistivities of tobacco dusts, yellow sand dusts and pine pollens are measured using a high voltage conductivity cell based on JIS B 9915. The resistivities of three kinds of indoor dusts are about $1{\times}10^7\;{\Omega}{\cdot}cm^2$ in the normal range and dust collection efficiency using an electrostatic precipitator at to face velocity of 1.0 m/s shows over 99% for the three kinds of indoor dusts.

• Journal of Animal Environmental Science
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• v.18 no.1
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• pp.1-8
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• 2012

The study was conducted to investigate the effects of climate on indoor environment of a swine house with natural. This study was tested in the beef swine stall at Young-in, Kyung-ki do. The test was experimented for the effect of interior environment by the outdoor environment and the interior-pan. The results are as follows. 1. In test 1 ($T_{out}$ : $25.7^{\circ}C$, without fan), an indoor air flow pattern was showed that entered from sidewall winch-curtain to went out of a indoor by the ridge winch-curtain. And the velocity of a section of the center was measured two times as large as the velocity of the floor. It is the acceleration of the velocity by thermal buoyancy. And, the entered air was rapidly dissipated by flow energy. So that in the swain livestock with sidewall winch-curtain is effected by thermal buoyancy. And the air temperature of the indoor was distributed more higher as compared with the outdoor temperature. This result is caused by the sensible heat from swine and the ventilation is restricted. 2. In test 2 (($T_{out}$ : $25.7^{\circ}C$, with fan), the velocity of a section of the center was measured more higher as compared with the test 1. And the variance of air velocity was distributed higher as compared with the test 1. This result is showed dead region of air flow with a fan operation. And, the variance of gas density was distributed lower as compared with the test 1.

• Journal of Environmental Health Sciences
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• v.36 no.5
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• pp.402-410
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• 2010

The objectives of this study were to evaluate the air quality surrounding an indoor swimming pool, to estimate the cancer risk based on the airborne exposure to trihalomethanes (THMs), and to examine the ventilation efficiency by Computational Fluid Dynamics (CFD). Chlorine and THMs were measured poolside, and in the staff room and reception area. The indoor swimming pool was modeled using the Airpak program, with ventilation drawings and actual survey data. Temperature, flow and mean age of the air were analyzed. Levels of chlorine poolside, and in the staff room, and reception area were $203\;{\mu}g/m^3$, $5\;{\mu}g/m^3$, and $10\;{\mu}g/m^3$, respectively. Chloroform was the dominant THM in all sampling sites and mean concentrations were $16.30\;{\mu}g/m^3$, $0.51\;{\mu}g/m^3$, and $0.06\;{\mu}g/m^3$ poolside, in the staff room and reception area, respectively. Bromodichloromethane and Dibromochloromethane levels were respectively estimated as $10.3\;{\mu}g/m^3$ and $1.7\;{\mu}g/m^3$ poolside, $1.3\;{\mu}g/m^3$ and $0.1\;{\mu}g/m^3$ in the staff room, and were not detected in the reception area. The cancer risks from inhalation exposure to THMs were estimated between $3.37{\times}10^{-7}$ and $1.84{\times}10^{-5}$. A short circulation phenomenon was observed from the supply air vents to the exhaust air vents located in the ceiling. A high temperature layer was formed within one meter of the ceiling, and a low temperature layer was formed under this layer due to the low velocity and high temperature of the supply air, and the improper locations of the supply air vents and exhaust air vents. The stagnation was evident at the above adult pool and the mean age of the air was 22 minutes. Disinfection by-products in the indoor swimming pool were present in higher concentrations than in the outdoor air. In order to increase the removal of pollutants, adjustment was required of the supply air volume and the supply/exhaust position.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.353-360
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• 2010

Recently H1N1(swine flu) and SARS has been infected widely in the world; we have to care about germs and virus in indoor air environment. The air sterilization system investigated in this study allows occupants to turn on/off and to control the incoming air speed and direction. To predict the performance of air sterilization system without real experiment, a simulation is considered to compare and analyze the performance of the air sterilization systems in a typical office space. Multiple system parameters including volume flow rate and velocity of supply air were varied and investigated during the simulation. The investigation result shows that difference (between simulation and experiment) was about 3.5% in case of minimum air flow rate and about 0.2% in case of maximum air flow rate. The results indicate that multi-zone simulation technique can be used to predict the performance of a sterilization system in personalized office.