• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.348-351
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• 2003

Trichloroethylene, which is one of the representative DNAPL, has been found in underground water sources as a result of the manufactural use, and disposal of the chemical. In this research, in situ air sparging method was chosen to reduce the TCE concentration from the source zone. The concentration reduction in the source zone resulting from air sparging is simulated using the modified STOMP Water-Air operational mode in a two dimensional axisymmetric domain and bench scale test is conducted to analyze the performance of air sparging. The results of laboratory tests are compared with numerical simulations.

• Journal of computational fluids engineering
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• v.10 no.1
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• pp.94-98
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• 2005

Accurate prediction of the fire-induced air velocity, temperature and smoke flow in underground utility tunnel becomes more important for the optimization of design and placement of heat and smoke detectors. In order to improve the safety of underground utility tunnel systems, the behaviors of fire-induced smoke flow and temperature distributions are investigated. Especially, two different cross-sectional shapes of tunnel, such as rectangular and circular types are modeled. Also, fire source is modeled as a volumetric heat source. Three-dimensional thermal-flow characteristics in an underground tunnel are solved by means of FVM using SIMPLE algorithm. The effects of shape geometry on the fire-induced flow characteristics are graphically depicted. It is desirable that heat and smoke detectors are installed on the cables and the top of the wall.

• Tunnel and Underground Space
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• v.5 no.1
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• pp.48-56
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• 1995

Recently, most of the underground excavation works are adopting heavy duty mobile diesel equipments which have outstanding merits in view of efficiency. However, these equipments are causing hygienic problems to the workers due to the various hazardous exhaust contaminants. Considering that there are always dead end workings in underground excavation sites, it is very important how to supply enough airflow to the workings to dilute diesel exhaust contaminants. This paper introduced the theoritical mechanism and actual trends of exhaust contaminants of diesel equipments under operation at local mines and suggested the design method of intake air volume in underground excavation workings using diesel equipments.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.901-905
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• 2008

This study was conducted to clarify the heat load characteristics and heat and moisture behavior of underground structures. The authors achieved this by carrying out a numerical analysis using simple heat diffusion and simultaneous heat and moisture transfer equations based on measurement data. This paper presents the results of a numerical analysis on the heat load characteristics and heat and moisture behavior of an underground basement and its surrounding ground under a condition of internal heat generation. The authors found it difficult to predict the heat behavior and heat load of the underground basement by simple heat diffusion alone. Accurate prediction of the thermal environment and heat load requires careful consideration of the influences of moisture and precipitation

• Journal of Life Science
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• v.10 no.1
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• pp.74-78
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• 2000

This study was investigated to evaluate the distribution of airborne microorganisms at underground shops in Seomyun and Nampodong, Pusan. The number of bacterial colonies on the nutrient agar plate plates were calculated by the open petri dish method for 30 minutes in indoor air of underground shops at every seasons in a year. There was no statistically significant difference between Seomyun and Nampodong in mean colony counts. Isolation rates of Gram positive rods was highest, and Gram positive cocci and Gram negative rods were followed. In Nampodong underground shops, Enterobacteriaceae strains was isolated. Mean colony counts according to seasons was higher at summer and autumn in Seomyun, and spring and winter in Nampodong. In near future, a study on the distribution of bacteria causing respiratory infection should be followed.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.573-581
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• 2019

Excavation of underground cavern and shaft was proposed for the construction of a ventilation facility in an urban area. A shaft connects the street-level air plenum to an underground cavern, which extends down approximately 46 m below the street surface. At the project site, the rock mass was relatively strong and well-defined joint sets were present. A kinematic block stability analysis was first performed to estimate the required reinforcement system. Then a 3-D discontinuum numerical analysis was conducted to evaluate the capacity of the initial support and the overall stability of the required excavation, followed by a 3-D continuum numerical analysis to complement the calculated result. This paper illustrates the application of detailed numerical analyses to the design of the required initial support system for the stability of underground hard rock mining at a relatively shallow depth.

• Journal of the Korean Institute of Rural Architecture
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• v.22 no.1
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• pp.1-12
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• 2020

The main purpose of the research is to prevent residents who are using underground parking lot from being exposed to pollusion, and to allow them to enjoy clean indoor environment. The study subject for the research are underground parking lots in 20 different apartments, 4 of them were constructed before 2000, 10 were constructed from 2000-2010, and the rest were constructed after 2010. By analyzing the air quality in these underground parking lots, we found out that O3, NO2, CO, PM10, Radon in all parking lots were not excessive compared to the standard limit. TVOC rate was measured with the value in between 312 ~ 2,137㎍/m3, with CO2 value in between 193~1,824 ppm, and HCHO with the value in between 0.01~1.52ppm. The lightning system in underground parking lots in apartments constructed before 2000 were using manual light control system, while automatic light control system was used in all apartments constructed after 2000, and the brightness of parking lots in apartments constructed before 2000 was quite low. The apartments constructed after 2000 are performing cleaning and ventilation due to management agreement, while the apartments constructed before 2000 are not performing regular cleaning and there was no mechanical ventilation system installed. The difference of indoor air quality was significant seasonally, daily, and yearly (year of construction), while illuminance was significantly different yearly.

• International Journal of High-Rise Buildings
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• v.3 no.2
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• pp.155-165
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• 2014

This study measured and compared the variation of ventilation rate and fan energy consumption according to various control strategies after installing wireless sensor-based pilot ventilation system in order to verify the applicability of demand-controlled ventilation (DCV) strategy that was efficient ventilation control strategy for underground parking lot. The underground parking lot pilot ventilation system controlled the ventilation rate by directly or indirectly tracking the traffic load in real-time after sensing data, using vehicle detection sensors and carbon monoxide (CO) and carbon dioxide ($CO_2$) sensor. The ventilation system has operated for 9 hours per a day. It responded real-time data every 10 minutes, providing ventilation rate in conformance with the input traffic load or contaminant level at that time. A ventilation rate of pilot ventilation system can be controlled at 8 levels. The reason is that a ventilation unit consists of 8 high-speed nozzle jet fans. This study proposed vehicle detection sensor based demand-controlled ventilation (VDS-DCV) strategy that would accurately trace direct traffic load and CO sensor based demand-controlled ventilation (CO-DCV) strategy that would indirectly estimate traffic load through the concentration of contaminants. In order to apply DCV strategy based on real-time traffic load, the minimum required ventilation rate per a single vehicle was applied. It was derived through the design ventilation rate and total parking capacity in the underground parking lot. This is because current ventilation standard established per unit floor area or unit volume of the space made it difficult to apply DCV strategy according to the real-time variation of traffic load. According to the results in this study, two DCV strategies in the underground parking lot are considered to be a good alternative approach that satisfies both energy saving and healthy indoor environment in comparison with the conventional control strategies.

• Journal of the Korean Society of Safety
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• v.10 no.3
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• pp.96-105
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• 1995

The better industry develops, the more spaces need but in the limited area. Most building become larger and more complicated if the more spaces need in the constant area. And this leads to do underground work in long period generally six(6) months for 6 basement stories due to the selection of TOP DOWN technique. Working environment in this underground area can be problems and should not be overlooked, because air quality in underground spaces become quickly worse. Recently, department name to control construction safety has been changed to ENVIRONMENT & SAFETY TEAM from SAFETY TEAM. This means that it is very important to control against environmental condition at site so much. Overall construction work as well as underground work should conform to the requirement of working environment, particularly against inhabitants around the construction area. Strut protection, one of earth protection method, in case to 40m long strut may become weaker due to thermal stress or its longitudinally compressive strain and the another one, earth anchor protection may not be applied to the site In case of encroaching on vertical underground borderline because of regulation to prohibit it. It is necessary that TOP DOWN technique should be introduced in order to solve the external and internal problem of the site such as difficulty level of the work, potential danger with excavating depth, and shortening workperiod. It is needed that improving way of working condition should be shown and simplified computer simulation program should be also provided for checking pollution level & ventilation, excluding of lighting problem here. Results measured with conformance to the Regulation for Working Environment Measurement, enforced by Ministry of Labor have been applied to the computer program developed here. Sample air taken at unit workplace which was considered as exposing condition of pollutant at breathing point and within a range of behavior of the workers, Identified exposing group in underground work, using Moded Flow Life Finally, three types of ventilation system, type I with blower & ventilator, type II natural supply with mechanical ventilation system, and type I mechanical ventilation with Drivent Fan Unit System are selected for this study.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.89-94
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• 2008

In this study it was evaluated that hybrid air conditioning and ventilation system to reduce energy consumption and keep on comfortable indoor environment in an underground shopping center. Room temperature by hybrid HAVC system was controled as $1.8{\sim}2.1^{\circ}C$ low and indoor humidity was controled as $4.1{\sim}5.0%RH$ low, and response was fast in $2.0{\sim}2.5$ times compared with conventional system. And also transportation efficiency of hybrid HVAC system was improved in about 27%, and total energy consumption rate of hybrid HVAC system is decreased in 16% compared with conventional system.