• KIEAE Journal
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• v.13 no.3
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• pp.111-120
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• 2013

The purposes of this study were to investigate the actual state of the indoor thermal and air environment in general apartment houses during winter in Cheongju City, to analyze the related factors with the indoor thermal and air environment, and to make suggestions for the improvement. A series of visiting field investigation was conducted in twenty units between 28th December, 2010, and 11th March, 2011. The field investigations included the measurement of physical indoor environmental conditions, the observation of architectural characteristics and resident's behavior, and the on-site questionnaire survey of residents. The measured values of each units were compared to evaluation standard and were categorized to group by the difference between units. Factors related to the difference of the measured values between the groups were analyzed. The findings are summarized as followed. The indoor temperature of apartment houses during winter in Cheongju City was generally suitable. The relative humidity was slightly dry, while the $CO_2$ concentration was found to be excessively high. The factors related indoor environment were analysed as heating operation, ventilation, gas range use, and hanging out the wash to dry in indoors.

• Journal of Environmental Science International
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• v.21 no.11
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• pp.1321-1331
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• 2012

To date, carbon and nitrogen co-doped photocatalysts (CN-$TiO_2$) for environmental application focused mainly on the aqueous phase to investigate the decomposition of water pollutants. Accordingly, the present study explored the photocatalytic performance of CN-$TiO_2$ photocatalysts for the purification of indoor-level gas-phase aromatic species under different operational conditions. The characteristics of prepared photocatalysts were investigated using X-ray diffraction, scanning emission microscope, diffuse reflectance UV-VIS-NIR analysis, and Fourier transform infrared (FTIR) analysis. In most cases, the decomposition efficiency for the target compounds exhibited a decreasing trend as input concentration (IC) increased. Specifically, the average decomposition efficiencies for benzene, toluene, ethyl benzene, and xylene (BTEX) over a 3-h process decreased from 29% to close to zero, 80 to 5%, 95 to 19%, and 99 to 32%, respectively, as the IC increased from 0.1 to 2.0 ppm. The decomposition efficiencies obtained from the CN-$TiO_2$ photocatalytic system were higher than those of the $TiO_2$ system. As relative humidity (RH) increased from 20 to 95%, the decomposition efficiencies for BTEX decreased from 39 to 5%, 97 to 59%, 100 to 87%, and 100 to 92%, respectively. In addition, as the stream flow rates (SFRs) decreased from 3.0 to 1.0 L $min^{-1}$, the average efficiencies for BTEX increased from 0 to 58%, 63 to 100%, 69 to 100%, and 68 to 100%, respectively. Taken together, these findings suggest that three (IC, RH, and SFR) should be considered for better BTEX decomposition efficiencies when applying CN-$TiO_2$ photocatalytic technology to purification of indoor air BTEX.

• Journal of Korean Society for Atmospheric Environment
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• v.6 no.1
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• pp.1-10
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• 1990

The purpose of the study was to analyze air quality in underground shopping centers using pattern recognition methods. In order to perform this, the concentraion of air pollutants such as $CO, NO_2, NO_x, SO_2$, and particulate matters was measured at the 11 different shopping centers in Seoul metropolitan area and the total of 47 samples were obtained at random based on the size of shopping centers. To introduce a new concept of the "average concentration" for the indoor air quality analyses, the various multivariate statistical analyses have been studied. Thus, a cluster analysis was applied to separate the samples into pseudo-patterns and a disjoint principal component analysis was used to generate homogeneous patterns after removing outliers from the pseudo-patterns. The 6 homogeneous patterns were then obtained as follows:the first pattern was a group of clean sites;the second a group of sites having high dust concentration;the third a group of sites having high dust and $NO_x$ concentration;the fourth a group of sites having low dust and $SO_2$ concentraion and high CO concentration;the fifth a group of sites having high $NO_2 and SO_2$ concentration;and the final a group of miscellaneous sites. Thus, the average concentration could be estimated for each pattern.h pattern.

• Journal of the Korean Institute of Educational Facilities
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• v.25 no.4
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• pp.19-30
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• 2018

The school classroom is a common living place where students spend 7 to 14 hours a day to prepare for their careers. Therefore, if the ventilation of the classroom is not properly performed, it may lead to the deterioration of learning ability due to the unclear air. The concentration of carbon dioxide in the classroom is reported to be high, and the increase in carbon dioxide concentration has a negative effect on the learner's academic performance. In this context, the purpose of this study is to propose a methodology for intelligent and responsive window opening-closing operation process that can reduce the concentration of $CO_2$ in the classroom in order to build a support space that can create an effective teaching-learning environment for adolescents. The specific objectives are as follows. First of all, we define the concept of window opening-closing operation. Secondly, twe develop the operation process of window opening-closing. Thirdly, we develop an algorithm for real-time window opening and closing (process) (Window Opening-Closing Operation Process). Finally, we verify the intelligent responsive window opening-closing operation process through developing examples of window opening-closing operation process using the parametric design program. This study is a preliminary study to develop algorithms necessary for window opening-closing operation. Based on the first-order algorithm, We simulated window opening-closing operations according to a hypothetical scenario. As a result, This study can show that the window is open and close depending on the $CO_2$ concentration, but the $CO_2$ concentration in the room is higher than outdoors. Consequentially, we suggest that it is necessary to develop an algorithm to supplement these results because window is often not working when the temperature difference between indoor and outdoor in winter is large.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.75-82
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• 2000

This paper presents the predicted results by CFD technique of air flow and contaminant distribution in a full-scale kitchen opened to a living room, ventilated by a exhaust hood. To analyze the characteristics of the indoor environment, the concept of contaminant index was defined. In this study, the locations of the gas range and the window were chosen as the parameters to investigate the indoor environment. The values of the contaminant index for several layout of the gas range and the window were calculated and compared. When the gas range is installed along the wall with specified window location, its position in relation to the wall has unnoticed effect on contaminant infer. Once the location of the gas range is fixed, the indoor air quality may deteriorate by the proximity of the window to the gas range. This is due to the shorter distance that external fresh air must travel within the kitchen before it reaches the exhaust fan.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.453-461
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• 2014

Objective: Based on the fact that fine particles are more likely to produce negative influences on the health of occupants as well as the quality of indoor air compared to coarse particles, it is critical to determine concentrations of aerosol particles with different sizes. Thus, this study focused on the size distribution and concentrations of aerosol particles in university buildings. Method: Aerosol particles in indoor air were collected from four areas: corridors in buildings(In-CO), lecture rooms(In-RO), laboratories(In-LR), and a cafeteria(In-RE). Samples were also collected from outside for comparison between the concentrations of indoor and outdoor particles. For the collection of the samples, an eight stage non-viable cascade impactor was used. Result: The average concentration of $PM_{10}$ in the samples collected from indoor areas was $34.65-91.08{\mu}g/m^3$,and the average for $PM_{2.5}$ was $22.65-60.40{\mu}g/m^3$. The concentrations of the aerosol particles in the corridors, lecture rooms, and laboratories were relatively higher than the concentrations collected from other areas. Furthermore, in terms of mass median aerodynamic diameter(MMAD), the corridors and lecture rooms had higher numbers due to their characteristics, showing $2.36{\mu}m$ and $2.11{\mu}m$, respectively. Laboratories running an electrolysis experiment showed $1.58{\mu}m$, and the cafeteria with regular maintenance and ventilation had $1.96{\mu}m$. Conclusion: The results showed that the $PM_{10}$ concentrations of all samples did not exceed indoor air quality standards. However, the $PM_{2.5}$ concentration was over the standard and, in particular, the concentration of fine particles collected from the laboratories was relatively higher, which could be an issue for the occupants. Therefore, it is important to improve the quality of the indoor air in university buildings.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.2
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• pp.191-200
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• 2011

A way to adsorptively remove indoor carbon dioxide at relatively lower concentration under ambient temperature was studied. A small lab-scale carbon dioxide adsorption and desorption reactors were prepared, and 5A and 13X zeolites were packed in this reactors to investigate their adsorption and desorption characteristics. The inflow carbon dioxide concentration was controlled to 5,000 ppm, relatively higher concentration found in indoor spaces with air quality problems, by diluting carbon dioxide with nitrogen gas. The flow rate was varied as 1~5 L/min, and the carbon dioxide concentration after this reactor was constantly monitored to examine the adsorption characteristics. It was found that 5A adsorbed more carbon dioxide than 13X. A lab-scale carbon dioxide desorption reactor was also prepared to investigate the desorption characteristics of zeolites, which is essential for the regeneration of used zeolites. The desorption temperature was varied as $25{\sim}200^{\circ}C$, and the desorption pressure was varied as 0.1~1.0 bar. Carbon dioxide desorbed better at higher temperature, and lower pressure. 5A could be regenerated more than three times by thermal desorption at $180^{\circ}C$. It is required to modify zeolites for higher adsorption and better regeneration performances.

• Particle and aerosol research
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• v.14 no.2
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• pp.25-33
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• 2018

In this study, the concentration of fine indoor dust and the size distribution of fine indoor dust were analyzed by measuring the dust generated during the cleaning process of an indoor office. We measured $PM_{10}$, $PM_{2.5}$, and $PM_{1.0}$ and analyzed the size distributions of dust larger than $0.3{\mu}m$ in diameter during cleaning. The results showed that the concentration of $PM_{10}$ increased rapidly during cleaning, however $PM_{1.0}$ did not increase. Before cleaning with a broom, the fine dust concentration was about $50{\mu}g/m^3$, but increased to about $400{\mu}g/m^3$ as cleaning progressed. In the case of indoor cleaning with a vacuum cleaner, the concentration of $PM_{10}$ increased during the cleaning process and the increase of $PM_{2.5}$ was relatively small. $PM_{1.0}$ did not increase as in the case of cleaning the broom.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.9
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• pp.506-515
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• 2013

The PFT (PerFluorocarbon Tracergas Technique) is of advantage to field surveys for evaluating the ventilation condition, due to its simplicity and convenience. On the other hand, it requires researchers to make some additional considerations that include uncertainties, such as the substance concentration distribution in indoor air, representativeness of a sampler, deviation of emission sources, and analysis error. In this study, the PFT and $CO_2$ tracer gas methods were applied simultaneously, to evaluate the accuracy of PFT on six ventilation conditions in the three-storied detached house. The air exchange and the outdoor air introduction a between and into zones were measured. As the results, deviations of PFT concentration distributions were observed at a sufficiently low level for an accurate determination for a house where the interior height was large, and there were relatively many partition walls. However, when a uniform airflow appeared in the indoor air, it was also validated that the indoor air would be exhausted without sufficient mixing, and consequently the measurement error of the PFT would be large.

• Journal of Environmental Science International
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• v.12 no.2
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• pp.207-215
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• 2003

The purpose of this study is to estimate the air quality of subway stations having underground platforms in Busan Metropolitan City, from September to November 2000, over seven times. The places of the investigation include Yonsan-dong station, Somyon station, Busan station, Nampo-dong station, and Dusil station. Samplings were conducted at three points in each station, i.e. gates, ticket gates, and platforms. CO, NO, $NO_2$, and $O_3$ were the main components of air for this analysis. In order to more fully understand station environments, we also measured an air temperature at each point. The results showed that the $O_3$ average concentration of Yonsan-dong station was higher than others with 38~51 ppb. The average concentration of NO was high at the ticket gate and platform at Somyon station (119 ppb, 122 ppb) and Nampo-dong station (102 ppb, 100 ppb). These results show that the air pollution of stations with underground shopping malls were higher than others. At Somyon station having a junction station, NO and $NO_2$ concentration levels of platform-2 (noncrowded) were higher than platform-1 (crowded). This is most likely due to the accumulation of air pollutants and inadequate ventilation systems. To find the relationship of the indoor (platform) and outdoor (gate), we analyzed the I/O ratio. The averages of CO and $O_3$ were both higher than one: 1.16 and 1.82, respectively. In the correlations between each material and the others, NO vs $NO_2$ was the highest with R=0.63. In the correlations between indoor and outdoor, $O_3$ was the highest with R=0.64.