• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.52-58
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• 2005

The assessment on characteristics of hydraulic behavior and water quality variations of underground reservoirs of buildings were studied. Firstly, it was thought that underground reservoir capacities($m^3$) of buildings should be not determinated by the uniform and same methods but be estimated on the basis of the dwelling areas on dominated households and their residential characteristics, because these characteristics influence significantly on actual water usages and patterns of buildings. Secondly, it was likely that the average reduction rate of residual chlorine in underground reservoirs were affected from the their capacities, because the average reduction rate of residual chlorine in underground reservoirs under $1,000m^3$ was 43 percent, on the other hand, that rate of underground reservoirs over $1,000m^3$ was 60 percent. Thirdly, through the field investigation, the retention time of drinking water in underground reservoirs were in the range from 0.3 day to 3.9 day. In addition to, the average reduction rate of residual chlorine were depended largely on the retention time of drinking water. When the retention time was under 24 hours, the average reduction rate of residual chlorine was 45 percent, and in case of over 24 hours, was 49 percent. Fourth, water level in underground reservoirs was averagely varied in the range from 0.1 m to 2.65 m at the height of underground reservoirs. If considered actual height of underground reservoirs, 37.6 percent of the height of underground reservoirs was only used. Consequently, the frequency of the inflow and outflow of drinking water in underground reservoir were very increased, and had an effect on the reduction of residual chlorine. Lastly, the investigations on hydraulic structure characteristics of underground reservoirs inside showed the locations of inflow and outflow of drinking water almost were in the opposite direction. And some buildings had several baffles in the middle. Nevertheless, their installations had no beneficial for the improvement of water quality.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.690-694
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• 2003

Groundwater preferentially flows through sediment layers with high permeability such as colluvium. Its flow paths are called groundwater vein streams. An underground temperature survey is a method to locate vein streams by underground temperature anomalies associated with flowing groundwater. A groundwater flow system near an irrigation reservoir located in the upper part of a landslide block was surveyed with this method. After a geomembrane lining was installed in the reservoir, the total cross-sectional area of the vein streams in the aquifer decreased to as little as 0.35 times that before installation of the liner. A change in groundwater quality also indicated that the mixing of groundwater with leaked water from the reservoir stopped after installation of the lining.

• Journal of Korean Society on Water Environment
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• v.39 no.2
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• pp.153-161
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• 2023

The reservoir tank in an apartment is crucial for maintaining the quality of drinking water after it has undergone treatment. Investigating the water quality and potential contaminants in the reservoir tank is essential to ensure the safety of the drinking water. This study examined the water quality and precipitated suspended solids that accumulate at the bottom of the reservoir tanks in four apartments located in Gyeonggi province. As a result of the water quality investigation, turbidity increased proportionally to the distance from the water treatment plant (WTP) to the household. Heavy metals were also detected in the reservoir tank inlet but not in the water supplied from the WTP. The precipitated suspended solids (SS) in the reservoir tank contain high levels of heavy metals and total organic carbon (TOC). The precipitated SS mainly consists of Al, Mn, and Fe, which are expected to be a combination with turbidity-inducing substances. The X-ray diffraction (XRD) analysis revealed the presence of γ-FeO(OH), MnO₂, and β-Fe₂O₃ in the SS. Additionally, F-EEM analysis indicates that the dissolved organic matter in the SS is mainly derived from a natural water source and microorganism activities, including metal-oxidizing bacteria and biofilms that can absorb metal ions. Based on these findings, several countermeasures can be taken to prevent the inflow of SS into the household, including regularly cleaning the reservoir tank, replacing or cleaning old pipes in the water supply system, and implementing monitoring and filtering systems to manage the SS.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.313-320
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• 2004

In this study, variable characteristics of drinking water and the influences on underground water reservoirs, rooftop water tanks, and service water pipes in the building were assessed. The influence of underground water reservoir material and water capacity on water quality also were assessed. The results are the following as; First of all, the drinking water passing through underground water reservoirs or service water pipes in the building, averagely metal component concentration more increased from percent of 41.3 to percent of 74.2 totally than other items of water quality. On the other hand, both residual chlorine and total solid highly decreased 65.6 percent and 35.3 percent, respectively. Therefore, it was thought that water quality could be getting worse for microorganism re-growth by residual chlorine reduction, and total solid also could be a cause for extraneous matters accumulated in water reservoir. Secondly, the variations on water quality of each stage for water supply system in the building were higher in water service pipes connected from rooftop water tanks to the tap than in underground water reservoirs. In addition to, among of twelve items on water quality, ten items on water quality except dissolved oxygen and residual chlorine increased. Therefore, it was thought that the influence of water service pipes connected from rooftop water tanks to the tap on water quality were higher than other stages of water supply system in the building. Thirdly, in case of materials of underground water reservoir, it was likely that the variation on water quality by stainless steel and concrete materials got some similar. In case of water capacity, the variations on water quality of underground water reservoirs over $1,000m^3$ higher than those under $1,000m^3$. That reasons was likely that the retention time(49.72 hours averagely) of underground water reservoirs over $1,000m^3$ was two times longer than it of those under $1,000m^3$(23.37 hours). Therefore, it was thought that the influence on water quality by materials were some similar, but in case of water capacity, the influence of underground water reservoirs were higher.

• Journal of Korean Society on Water Environment
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• v.38 no.6
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• pp.275-281
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• 2022

To maintain water quality after water treatment, monitoring whether the quality of treated tap water quality changes is essential. However, current investigations are insufficient to prevent secondary contamination in drinking water supply systems. This study investigated Gyeonggi's e apartment where a red water problem occurred and monitored the water quality and corrosiveness of the overall water supply system to the apartment from June 2021 to April 2022. In a comparison of drinking water quality after water treatment and the influent of the reservoir, turbidity and heavy metal concentrations were increased and residual chlorine was decreased due to increases in temperature. Correlation analysis and principal component analysis (PCA) indicated that a low level of residual chlorine may cause the abscission of Mn²⁺ and Fe²⁺ through microorganism activation, which also causes a high level of turbidity. The corrosion index (LI) in the influent of the reservoir tank was increased due to Ca²⁺ and temperature. These results indicate that the corrosiveness of drinking water and the deterioration of drinking water quality were mainly increased between the drinking water treatment plant and the reservoir tank's influent. The findings provide clear evidence that it is essential to manage water supply systems and reservoir tanks to prevent the secondary contamination of drinking water.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.215-225
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• 2019

The mechanical behavior of rock is essential to estimate the capacity and long-term stability of $CO_2$ storage in deep saline aquifers. As the depth of reservoir increases, the pressure and temperature that applied on the rock increase. To answer the question of how the confining pressure and temperature influence the mechanical behavior of reservoir rock, triaxial compression experiments were carried out on brine-saturated sandstone at elevated temperature. The triaxial compressive strength of brine-saturated sandstone was observed to decrease with increasing testing temperature, and the temperature weakening effect in strength enhanced with the increase of confining pressure. Sandstone specimens showed single fracture failures under triaxial compression. Three typical regions around the main fracture were identified: fracture band, damaged zone and undamaged zone. A function was proposed to describe the evolution of acoustic emission count under loading. Finally, the mechanism of elevated temperature causing the reduction of strength of brine-saturated sandstone was discussed.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.1-6
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• 2021

The average annual rainfall in Busan to increase, and in case of Oncheon-Chen in Busan, frequent flooding occurred frequently. The middle and lower reaches of the Oncheon-Chen are relatively flat and urban areas are developed. Therefore, due to the frequent flooding of rivers and the large flood damage, a method of effectively eliminating the flow rate of Oncheon-Chen in the event of heavy rain is needed. In this study, underground waterway was established in the east of Hoedong-Reservoir as a measure to reduce floods in hot springs and simulated with EPA-SWMM. The information needed to construct the basin was utilized by GIS. In middle part of the Suyeong-Gang, there is a Hoedong-Reservoir and a dam is installed and has better conditions than the Nakdong-Gang. It also analyzed the effect of the Oncheon-Chen flow through the underground waterway on the Suyeong-Gang when it was transferred to the Hoedong-Reservoir. It was analyzed that the flood reduction rate at the flood risk points set up in this study was reduced by 24.64% on average when the underground waterway was installed, and the inflow of the water into the Suyeong-Gang increased by 1% on average when the flow rate was excluded by the Suyeong-Gang.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.304-324
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• 2018

Singapore government is strongly promoting the development and utilization of underground space in national level due to the nature of the city state which lacks the land. As well as conventional underground utilization in shallow depth such as metro and underground roads, large rock cavern utilization has been started after the successful completion of the underground ammunition depot in the rock, and Jurong Rock Cavern, the second large underground cavern project has just been completed. In this paper, after evaluating the conditions of the underground development in rock mass through the analysis of the geology of Singapore, the history and current status of underground development are examined. Several creative development plans from Singapore government such as underground reservoirs, underground automation logistics systems and underground warehouses storage etc. are introduced with technical issues. This paper also discusses the problems and issues related to the development of large underground space in rock mass in Singapore. It is expected that such active development of underground space in Singapore can give many opportunities and also challenges for rock engineering and industry in the future.

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.5-14
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• 2020

This study analyzed the reinforcement effect by conducting laboratory test, model test and program analysis to utilize the surface stabilizer used for the restoration work of collapsed slopes as a reinforcing material for aging reservoirs that exhibits a curing reaction similar to cement. Based on the results of the laboratory test, a model test and program analysis were performed by applying 9% of the mixing ratio. As a result, when the surface stabilizer was used in aging reservoir, it was found that the flow of water only occurred on part of the slope and underground in reservoir. And the water flow could be reduced inside the reservoir. In addition, it was analyzed that the seepage discharge could be reduced by about 42% and the saturated area within the reservoir by about 73%, thereby securing the stability of the aged reservoir.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.9-20
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• 2013

Depleted gas reservoir has been already explored and its geologic data, along with its reservoir properties, are already known through seismic exploration and drilling. Therefore it would be less difficult to develope a gas storage from depleted gas reservoir. Cushion gas which remains in the reservoir to maintain pressure affects withdrawal rate of working gas in underground gas storage. In this study, we attempted to investigate the relationship between cushion gas and withdrawal rate using a commercial simulator. From the analyses of the results, it is found that the minimum limit for a cycle of 5-month injection and 5-month withdrawal is 10 wells with 50% cushion gas, and 12 wells with 60% cushion gas for a cycle of 7-month injection and 3-month withdrawal.