• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.143-148
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• 2007

Recently indoor air pollution caused by exposing hazardous chemicals (VOCs, formaldehyde) due to undiscriminated use of new construction materials and air-tightness to save energy is becoming a big issue. We have developed technologies to estimate the amounts of contaminants from constructions materials and method. We have further developed construction technologies to reduce and characterize these contaminants. The developed technologies were then refined to eliminate defects through considering field applicability.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.166-176
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• 2003

Experiments have been conducted in order to make comparisons of a alternative refrigerant (R-410A) cycle characteristic with an existing refrigerant (R-22) cycle characteristic in terms of cooling capacity and coefficient of performance (COP). The parameters examined in the present work include air flow rate, indoor/outdoor air temperatures, and indoor relative humidity. These two refrigeration cycles share all components except compressor, accumulator, oil separator, and piping connecting them. The measurements were made using an air-enthalpy calorimeter. The experimental results show that the R-410A cycle has many advantages over indoor conditions while the R-22 cycle has better performance over outdoor conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.202-211
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• 2007

Ventilation system is being recommended as an effective tool to improve indoor air quality (IAQ) in apartment houses. Recently, in Korea, apartment house suppliers must establish ventilation system in apartment houses in law. In this study, improvement of IAQ by establishing mechanical ventilation system at apartment house was investigated by mockup test. Seven apartment houses were arranged for the test and improvement of IAQ was examined under the various conditions of ventilation rates, ventilator type and duct works. The results of this study show that IAQ in the test houses which were established mechanical ventilation system was improved about from 30% to 40% compared with IAQ in the apartment house which was not established ventilation system. However, there were no apparent concentration differences between the cases of changing ventilation rates, ventilator types and ductworks.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1799-1802
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• 2008

More than 7 million people use the Seoul metropolitan subway network daily. This number tends to increase due to the increase of oil price. Indoor air quality of electrical multiple unit (EMU) is strongly affected by outdoor air quality, however, indoor thermal comfort is subjected to heating, ventilating, and air conditioning (HVAC) system of EMU. In general, air temperature, humidity, air velocity, surface temperature, and illumination are key parameters affecting thermal comfort of passenger. It is known that the well-designed HVAC system should improve the thermal comfort of passengers and should increase the energy efficiency of HVAC system also. In this study, we analyzed the thermal comfort of advanced EMU developed by Korea Railroad Research Institute by using the computational fluid dynamics (CFD) in order to find the optimum HVAC system which can improve thermal comfort of passengers with a minimal energy use.

• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.468-477
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• 2009

To evaluate the current indoor air quality condition of private academic facilities in Korea and investigate its association with subjective symptoms of student residing at the same academic facilities, air quality monitoring was carried out in total of 20 academic facilities located in Seoul, Daejon and Chungnam from the beginning of January to the end of April, 2009. To assess the air quality condition of academic facilities, 6 air pollutants with temperature and humidity were measured simultaneously inside and outside of academic facilities. The rate of exceeding the Indoor Air Quality (IAQ) guideline concentrations in 6 air pollutants were 5%, 85%, 15%, 5%, 10% and 30% for CO, $CO_2$, PM10, HCHO, TVOCs and TBC, respectively. A questionnaire on 16 subjective symptoms related to indoor air quality was given to 342 students who studied at the 20 academic facilities. The most frequent symptom of students was 'I feel easily tired or sleepy', and this was followed by 'I feel muscular pain or stiffness on shoulder, back and neck'. The association of net difference (subjective symptoms at the academic facility - subjective symptoms of the usual situation) with air pollutants was analyzed using spearman rank correlation. In logistic analysis using proportional odds method, the students whose indoor air concentration of HCHO was ${\geq}60{\mu}g/m^3$ hadsignificant odds of having more subjective symptoms of 'My eyes are dry or feel irritated or itching' (OR=5.026: CI=1.587-15.911), 'I feel easily tired or sleepy' (OR=2.956: CI=1.072-8.152), 'I lose my concentration and I feel my memory is falling' (OR=7.745: CI=1.938-30.955) and 'I feel dizzy' (OR=4.424: CI=1.292-15.149) than those of <$60{\mu}g/m^3$.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.745-751
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• 1998

The well-mixed room model has been traditionally used to predict the concentrations of contaminants in indoor environments. However, this is inappropriate because the flow fields in many indoor environments distribute contaminants non-uniformly, due to imperfect air mixing. Thus, some means used to describe an imperfectly mixed room are needed. The simplest model that accounts for imperfect air mixing is a two-zone model. Therefore, this study on development of computer program far the two-zone model is carried out to propose techniques of estimating the concentration of contaminants in the room. To do this, an important consideration is to divide a room into two-zone, i.e. the lower and upper zone assuming that the air and contaminants are well mixed within each zone. And between the zones the air recirculation is characterized through the air exchange parameter. By this basic assumption, the equations for the conservation of mass are derived for each zone. These equations are solved by using the computational technique. The language used to develope the program is a VISUAL BASIC. The value of air exchange coefficient($f_12$) is the most difficult to forecast when the concentrations of contaminants in an imperfectly mixed room are estimated by the two-zone model. But, as the value of $f_12$ increases, the air exchange between each zone increases. When the value of $f_12$ is approximately 15, the concentrations in both zone approach each other, and the entire room may be approximately treated as a single well-mixed room. Therefore, this study is available for designing of the ventilation to improve the air quality of indoor environments. Also, the two-zone model produces the theoretical base which may be extended to the theory for the multi-zone model, that will be contributed to estimate the air pollution in large enclosures, such as shopping malls, atria buildings, atria terminals, and covered sports stadia.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.831-841
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• 2006

The study on school indoor air quality was carried out at classrooms, computer-rooms, laboratories and play- grounds for carbonyl compounds including formaldehyde during the winter time from November to December 2004 and during the summer time from June to July 2005. The sampling was conducted under the general school condition without any artificial intervention such as the sealing, ventilating or heating at indoor environments. The concentrations of formaldehyde at all types of indoor environments were lower than air quality standard of $120{\mu}g/m^3$ for public facilities. The mean concentrations of formaldehyde at indoors were $4.5{\sim}6.1$ times higher than those at outdoors. From the comparison between two year and one year old schools after construction, the concentrations of formaldehyde in two year old school were $30{\sim}38%$ lower than those in one year old school measured at classrooms and laboratories.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.19-26
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• 2006

This study was undertaken to determine the concentrations of 15 aldehydes in air samples collected from 21 households including 9 atopy patient's homes and to assess the extent of exposure and risk for an individual due to inhalation. Of all the aldehydes identified in both indoor and outdoor environment, formaldehyde and acetaldehyde were the most abundant aldehydes, which were occupied $60\%\;and\;17\%$ of total amount, respectively. The geometric mean concentration of formaldehyde and acetaldehyde in indoor air were $170.5\pm1.9\;{\mu}g/m^3\;and\;47.3\pm1.5\;{\mu}g/m^3$, respectively. There existed a strong correlation between formaldehyde, acetaldehyde and other aldehydes. And the ratio of indoor and outdoor concentrations (I/O) exceeded 1.0 for almost every measured aldehydes except m-tolualdehyde... No associations were found between the level of aldehydes and either housing characteristics or living habits in most of the samples with only a few exception. And the concentrations of all aldehydes indoor air between atopy patient's homes and control homes were not significant(p>0.05). Formaldehyde and acetaldehyde exposures and risks were estimated by using the inhalation unit risk, mean concentrations and the 95th percentiles, and which were $2.6\times10^{-3}\;and\;1.1\times10^{-4}$, respectively. The mean and the 95th percentile risk estimates were 25 times higher for formaldehyde than for acetaldehyde in homes.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.47-57
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• 2013

Studies evaluating the health effects of hazardous air pollutants assume that people's exposure to typical pollutant level is the same as specific regional pollutant level. However, depending on social and demographic factors, time-activity pattern of people can vary widely. Since most people live in indoor environments over 88% of the day, evaluating exposure to hazardous air pollutants is hard to characterize. Objective of this study was to estimate the exposure levels of university students of $NO_2$, VOCs(BTEX) and $PM_{10}$ using the scenarios with time-activity pattern and indoor concentrations. Using data from time-use survey of National Statistical Office in 2009, we investigated time-activity pattern of university students and hourly major action. A total of 1,057 university students on weekday and 640 on weekend spent their times at indoor house 13.04 hr(54.32%), other indoors 7.70 hr(32.06%), and transportation 2.36 hr(9.83%). Indoor environments in which university students spent their times were mainly house and school. Air pollutants concentrations of other indoor environments except house and school such as bar, internet cafe and billiard hall were higher than outdoors, indicating that indoor to outdoor ratios were above 1. According to three types of exposure scenarios, exposure to air pollutants could be reduced by going home after school.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.9
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• pp.863-872
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• 2005

It is important to control indoor environment for influence on health and comfort of occupants in large-sized discount stores. On the other hand large-sized discount stores have a large number of visitors, vestibules, open spaces, high energy consumption and increasing of outside air intake. This study aims to offer the design data of building services system that can save energy and control environment through field measurement selecting two large-sized discount stores. Indoor environment factors such as temperature, relative humidity, air velocity and concentrations of $CO_2$, CO gas and TSP were measured and evaluated. In each case of $CO_2$, and CO gas, its maximum values were 2,800 ppm and 20 ppm. So proper strategy for the indoor air quality is indispensable in this type of building. Dry bulb temperature varies from $18^{\circ}C$ to $28^{\circ}C$ according to a measuring point and time. From this results, it is inferred these buildings had excessive equipment capacity. In terms of economical and environmental points, these data will be utilized to the design of HVAC system of retail facilities.