• Journal of the Korean Geosynthetics Society
• /
• v.7 no.4
• /
• pp.1-8
• /
• 2008

Soil vapor extraction (SVE) is an effective and cost efficient method of removing volatile organic compounds (VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. The aim of this study is to investigate numerically the performance of a prefabricated vertical drain (PVD) as a SVE well, and the pattern of the induced air flow. A validated numerical model for a single PVD extraction well is developed based on the result of a well-designed laboratory model test. The validity of the simple analytical approach to determine air permeability based on the results of model tests is also discussed.

• Journal of the Korean Society of Safety
• /
• v.27 no.1
• /
• pp.1-6
• /
• 2012

In crowded subway stations indoor air quality (IAQ) is a key factor for ensuring the safety and health of passengers. Since physical variables that describing IAQ such as the concentration of particulate, $CO_2$, VOCs and biological agents need to be closely monitored and controlled in multiple locations within subway stations and in remote sites, concept of web-based monitoring and control network using both wireless and wired media needs to be implemented. Connecting remote wireless sensor network and device (LonWorks) networks to the IP network based on the concept of VDN can provide a powerful, integrated, distributed monitoring and control performance. In this study, performance of wireless and wired network in VDN for monitoring and control of IAQ in subway stations is evaluated. Specifically, delay induced in wireless and wired networks, and data transmission rate are evaluated. A key parameter is identified in assuring safety and health of passengers in subway stations.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2005.11a
• /
• pp.307-310
• /
• 2005

In recent years, our society is confronted with many environmental problems. Among them, Especially, Sick House Syndrome is brought into relief as a society's issue and the people's concern of Indoor Air Quality is also increased. Nowadays, about 20percent of korean children is suffered from allergic respiratory diseases such as asthma or rhinitis. From student's physical and mental point of view, indoor environmental condition of school is very important and must be kept by strict regulation Therefore, the aim of this thesis is focused on the measurement and analysis of indoor air quality of classroom.

• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.6
• /
• pp.876-887
• /
• 2006

Recently, there have been a large number of remodeling (or renovation) works in old buildings in urban areas. Compared to new buildings, environmental risk might be more significant in such buildings where remodeling works are going on, since some parts of the building may still be in service for people. This study was carried out to investigate the impacts of remodeling works on the indoor air quality (IAQ) of a large building (a 22 stories university library). Indoor air monitoring was conducted during and after the remodeling works every two weeks for a one year period, and target compounds included BTEX, styrene, TVOC, carbonyl compounds such as formaldehyde and acetaldehyde. $CO,\;CO_2,\;PM_{10}$, and $PM_{2.5}$. Overall, the IAQ appeared to be recovered within two months after the remodeling works. However, in some places, concentrations of formaldehyde, toluene, xylene. and ethylbenzene showed higher levels even after works than those during the works. The results indicate that painting, glues and office furnitures are major sources of aromatic VOCs and formaldehyde. Therefore, in order to decrease the concentrations of toxic VOCs, the use of environmental-friendly building materials is strongly recommended during the remodeling works. In addition, IAQ control and management scheme (for example, baking the inside of the building) should be taken into consideration before reopening the buildings.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.4
• /
• pp.121-129
• /
• 2011

Hydrocarbons which are the main sources of VOCs from motor vehicles are emitted not only from the engine exhaust gas but also from evaporation of the fuel in storage and supplying systems. Evaporative emissions from gasoline fuel systems could be classified by diurnal, hotsoak and running loss. Diurnal loss test procedures are different as countries. Korea introduced new evaporative regulation in 2009 with 24hour VT-shed test procedure and relaxed emission standards. The estimations on different test procedures in this study show that the new Korean regulation get a little more severe than before and the 2 day diurnal loss test of U.S. is the most severe. So the test procedures as well as the stronger standards should be considered in the next evaporative emission regulation to reduce VOCs from motor vehicles. The important parameters to affect evaporative emissions are air and fuel temperature and fuel vapor pressure. Diurnal loss increases exponentially as rising air temperature and vapor pressure. The effects of vapor pressure on running loss are different as the capacities of canisters. Tests with simulating real temperature and driving conditions show that hydrocarbons in evaporative emissions could be more than those in exhaust gas in summer season because of the higher air temperature.

• Journal of Environmental Science International
• /
• v.21 no.2
• /
• pp.241-251
• /
• 2012

The emissions of several air pollutants ($NO_x$, CO, VOCs, etc.) for the replacement of all diesel buses by Compressed Natural Gas (CNG) buses were estimated in the Busan Metropolitan Area (BMA). These emissions were calculated from emission factors considering the different driving speeds with bus routes, distance traveled, and deterioration factors. For the purpose of this study, three categories of fuel type were selected: (1) the combination of diesel (65%) and CNG buses (35%) (DSL+CNG case), (2) all diesel buses (DSL case), and (3) all CNG buses (CNG case). The emissions of $NO_x$ and CO in the CNG case were estimated to be significant decreases (by about 50% and 98%, respectively) relative to the DSL case. Conversely, the emission of VOCs (980.7 ton/year) in the CNG case were a factor of 3.3 higher than that (299.8 ton/year) in the DSL case. In addition, the diurnal variations of emissions between two city buses (e.g. diesel and CNG) and all other vehicles were distinctly different because the two city buses operate at a regular time interval. Our overall results suggest the possibility that the pollutant emissions from the CNG buses can exert less influence on air quality in the target area than those from the diesel buses.

• Asian Journal of Atmospheric Environment
• /
• v.11 no.4
• /
• pp.300-312
• /
• 2017

To improve the understanding of secondary organic aerosol (SOA) formation from the photo-oxidation of anthropogenic and biogenic precursors at the regional background station on Baengnyeong Island, Korea, gas phase and aerosol chemistries were investigated using the Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS) and the Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS), respectively. HR-ToF-AMS measured fine particles ($PM_1$; diameter of particle matter less than $1{\mu}m$) at a 6-minute time resolution from February to November 2012, while PTR-ToF-MS was deployed during an intensive period from September 21 to 29, 2012. The one-minute time-resolution and high mass resolution (up to $4000m{\Delta}m^{-1}$) data from the PTR-ToF-MS provided the basis for calculations of the concentrations of anthropogenic and biogenic volatile organic compounds (BVOCs) including oxygenated VOCs (OVOCs). The dominant BVOCs from the site are isoprene (0.23 ppb), dimethyl sulphide (DMS, 0.20 ppb), and monoterpenes (0.38 ppb). Toluene (0.45 ppb) and benzene (0.32 ppb) accounted for the majority of anthropogenic VOCs (AVOCs). OVOCs including acetone (3.98 ppb), acetaldehyde (2.67 ppb), acetic acid (1.68 ppb), and formic acid (2.24 ppb) were measured. The OVOCs comprise approximately 75% of total measured VOCs, suggesting the occurrence of strong oxidation processes and/or long-range transported at the site. A strong photochemical aging and oxidation of the atmospheric pollutants were also observed in aerosol measured by HR-ToF-AMS, whereby a high $f_{44}:f_{43}$ value is shown for organic aerosols (OAs); however, relatively low $f_{44}:f_{43}$ values were observed when high concentrations of BVOCs and AVOCs were available, providing evidence of the formation of SOA from VOC precursors at the site. Overall, the results of this study revealed several different SOA formation mechanisms, and new particle formation and particle growth events were identified using the powerful tools scanning mobility particle sizer (SMPS), PTR-ToF-MS, and HR-ToF-AMS.

• Applied Chemistry for Engineering
• /
• v.16 no.2
• /
• pp.194-199
• /
• 2005

The principle of vortex cyclone was applied to enhance the treatment efficiency of waste air streams containing particulate matters, phenol, and others. Adsorption, condensation, and/or coagulation could be induced at low temperature zone formed by Joule-Thomson expansion as the pressurized air and pulverized activated carbon were introduced at the tangential direction into the cyclone system applied with the coaxial funnel tube of vortex cyclone. Easily condensible vapors were adsorbed and/or condensed forcibly on coagulated or condensed materials which were formed as cores for coagulation or condensation by themselves or on pulverized activated carbons. These types of coagulation or condensation rates were rapidly promoted by increase in their diameter. The maximum removal efficiency obtained from this experiment for the removal of carbon dioxide and phenol was about 87.3 and 93.8 percent, respectively. Phenol removal efficiency was increased with the relative humidities and enhanced by pulverized activated carbon added. The Joule-Thomson coefficients were increased with the pressure of air injected in the range of the relative humidities between 10% and 50%. It is believed that the moisture, particulate matters, and the pressure of the process air introduced could control the removal efficiency of VOCs.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.8
• /
• pp.649-655
• /
• 2006

The recent indoor air quality problem in a newly-built apartment house is resulted from the improvement of airtightness performance and the use of the building material contained harmful chemical substances. As a result, these cause indoor air quality gradually to become worse and the harmful effect on occupant health called Sick House Syndrome. The most effective solution to improve the indoor air quality is to encourage the use of green building material. However, if the house is built with general building material, ventilation with outdoor air is alternative to dilute the pollutant concentration. The purpose of this re-search is to find optimum ventilation time in a newly-built apartment house at which the ventilatoris installed. It is found that the HCHO and toluene concentrations are remarkably decreased with the elapse of ventilation time and the concentration reduction rate is increased with increment of air change rate after one hour after operating the ventilator.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.1244-1249
• /
• 2006

Because students are spending more time in their classroom for learning and study, indoor air quality problems in school classrooms are very important. when the classroom is built for the first time, namely newly built school, the selection of inside finishing material is directly connected with indoor air quality problems especially with HCHO and TVOC. But until now, there is no plenty of study about this. Moreover, there are some concerns about the desks and chairs which are used in classroom will affect the air quality. but almost no study is being made at all Therefore, this study focuses on the field survey and analysis of classroom indoor air quality in newly built schools in Changwon. In this study filed surveys and analysis are conducted as follows. 1) The effect of the material difference in general classroom. 2) The effect of the material and loading ratio difference in special classroom. 3) The effect of the desks and chairs in general classroom.