• Title/Summary/Keyword: underground air

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A Study on the Optimum Cooling Span of the Underground Power Transmission Cable Equipped by a Forced Cooling System (전력구내 지중케이블 강제냉각에서의 적정냉각구간에 관한 연구)

  • Lee, J.H.;Chung, S.H.;Kim, J.G.;Park, M.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.2 no.1
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    • pp.49-62
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    • 1990
  • The forced cooling system has been widely applied to passing more electric current in the underground power transmission cable technology. In this paper, the optimum cooling span of the in-trough-indirect water cooling method within an electric tunnel was investigated. A parametric study was performed for the cable currents, the coolant flow rates, and the coolant inlet temperatures. As a result, the temperature of the inlet air has been found as the most important parameter in determination of the optimum cooling span.

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A Study on the Indoor Air Quality of Public Entertainment Facilities. (공공위락 시설의 실내 공기환경에 관한 연구)

  • 정재국
    • Journal of the Korean housing association
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    • v.9 no.1
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    • pp.143-152
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    • 1998
  • This study aims to suggest ventilation design data for Public Entertainment Facilities in relation to Indoor Air Quality. The concentration of indoor air pollution such as CO, CO2, RH, Radon, HCHO, TSP was investigate, and the reguired ventilation rate of Public Rooms was calculated. As resuits of this study, the following conclusion could be obtained. Field measurement of P.E.F reveals that the concentration of CO2 was mist polluted and higher than IAQ standard, while that of other pollutats did not exceed the standard. In underground the concentration of CO2 increased 1130ppm(2 persons) 2170ppm(4 persons) 1970ppm(6 persons). The CO2 pollution was serions problem in underground more than second floor, in only exhaust ventilation system more than exhaust and supply system.

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Risk Assessment with the Development of CAES (Compressed Air Energy Storage) Underground Storage Cavern (CAES(Compresses Air Energy Storage) 지하 저장 공동 개발에 따른 리스크 사정)

  • Yoon, Yong-Kyun;Seo, Saem-Mul;Choi, Byung-Hee
    • Tunnel and Underground Space
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    • v.23 no.4
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    • pp.319-325
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    • 2013
  • The objective of this study is to assess risks which might occur in connection with the storage of the highly compressed air in underground opening. Risk factors were selected throughout literature survey and analysis for the characteristic of CAES. Large risk factors were categorized in three components; planning and design phase, construction phase, and operation & maintenance phases. Large category was composed of 8 medium risk groups and 24 sub-risks. AHP technique was applied in order to analyze the questionnaires answered by experts and high-risk factors were selected by evaluating the relative importance of risks. AHP analysis showed that the operation & maintenance phases are the highest risk group among three components of large category and the highest risk group of eight medium risk groups is risk associated with the quality and safety. Risk having the highest risk level in 24 sub-risks is evaluated to be a failure of tightness security of inner containment storing compressed air.

Analysis of air pollution in subway area of Busan Metropolitan City (부산광역시 지하철역 지하공간의 대기오염 특성)

  • Lee, Hwa-Woon;Jang, Nan-Sim;Kwak, Jin;Lee, Hee-Ryung;Kim, Hee-Man
    • Journal of Environmental Science International
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    • v.11 no.3
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    • pp.169-176
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    • 2002
  • The purpose of this study is designed to estimate the air quality of subway stations that have the underground platforms in Pusan Metropolitan City, from September to November 2000, over seven times. The subjects include Yonsan-dong station, Somyon station, Pusan station, Nampo-dong station, and Tushil station. The samplings were conducted at three points of each station, i.e. gate, ticket gates, and platforms. The major materials for analysis were CO, NO, NO$_2$, and $O_3$. The experiment was conducted at 7:00 pm with KIMOTO HS-seven Handy sampler and Tedlar Bag of SKC INC(U.S.A). In order to more fully understand station environments, we also measured temperature at each point. The results showed that $O_3$ average concentration at Yonsan-dong station was higher than others with 38~51 ppb. The average concentration of NO was high at ticket gate and platform at Somyon station(119 ppb, 122 ppb), Nampo-dong station(102 ppb, 100 ppb). These results show that the air pollution of stations with underground shopping malls was higher than others. At Somyon station having a junction station, NO and NO$_2$ concentration level of platform-2(noncrowded) was higher than platform-1(crowded). This is most likely due to the accumulation of air pollutants and inadequate ventilation systems.

A Study on the Evaluation of DCSG Steam Efficiency of Oil Sand Plants for Underground Resources Development (지하자원개발을 위한 오일샌드플랜트의 DCSG 증기생산효율 평가에 관한 연구)

  • Young Bae Kim;Kijin Jeong;Woohyun Jung;Seok Woo Chung
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.18 no.4
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    • pp.12-21
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    • 2022
  • Steam assisted gravity drainage(SAGD) is a process that drills well in the underground oil sands layer, injects hightemperature steam, lowers the viscosity of buried bitumen, and recovers it to the ground. Recently, direct contact steam generator(DCSG) is being developed to maximize steam efficiency for SAGD process. The DCSG requires high technology to achieve pressurized combustion and steam generation in accordance with underground pressurized conditions. Therefore, it is necessary to develop a combustion technology that can control the heat load and exhaust gas composition. In this study, process analysis of high-pressurized DCSG was conducted to apply oxygen enrichment technology in which nitrogen of the air was partially removed for increasing steam production and reducing fuel consumption. As the process analysis conditions, methane as the fuel and normal air or oxygen enriched air as the oxidizing agent were applied to high-pressurized DCSG process model. A simple combustion reaction program was used to calculate the property variations for combustion temperature, steam ratio and residual heat in exhaust gas. As a major results, the steam production efficiency of DCSG using the pure oxygen was about 6% higher than that of the normal air due to the reducing nitrogen in the air. The results of this study will be used as operating data to test the demonstration device.

Experimental Study for the Capacity of Ordinary and Emergency Ventilation System in Deeply Underground Subway Station (대심도 지하역사 승강장 및 대합실 평상시/비상시 급·배기 풍량에 대한 실험적 연구)

  • Jang, Yong-Jun;Lee, Ho-Seok;Park, Duck-Shin
    • Journal of the Korean Society for Railway
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    • v.15 no.6
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    • pp.579-587
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    • 2012
  • Shin-gumho station in Seoul underground subway have been selected to be experimentally investigated and analyzed for the real air supply & exhaust capacity compared to the original capacity of ordinary and emergency condition. The depth of Shin-gumho station is 43.6m which consists of the island-type platform ($8^{th}$ floor in underground) and a two-story lobby (first & second floor in underground). An emergency staircase connects between the platform and the lobby. Hot-wire anemometer, capture hood, wind vane & velocity meter and data acquisition systems are employed to perform the automatic measurement in this experiment. For ordinary case, air supply and exhaust capacity in the lobby were reduced by 34% and 46% compared to the original capacity, respectively. Air supply and exhaust capacity in the platform were reduced by 66% and 38%, respectively. For emergency case, air supply in the lobby was reduced by 42% and air exhaust in the platform was reduced by 28% compared to the original capacity. Therefore, air pollution in the station is expected to be worse in the ordinary environment and smoke control capability in the platform will be weakened in case of fire emergency.

Fluctuation Features and Numerical Model for Underground Temperature in Shallow Subsurface Soil (천층 토양 내 지중온도 변동 특성과 수치모델 평가)

  • Jeong, Jaehoon;Kim, Gyoobum;Park, Hyoungki;Kim, Hyoungsoo;Kim, Taehyung
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.5
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    • pp.35-42
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    • 2015
  • This is conducted to observe underground temperature and to analyze its change affected by climate condition and soil infiltration in the mountainous area, Yesan region, Chungcheong-namdo province. Additionally, underground temperature change is also simulated using air temperature and soil thermal properties with a numerical model. Soil temperature monitoring data acquired from each depth, 20 cm, 50 cm, and 100 cm, indicates that the data within 50 cm in depth shows peak-shaped big fluctuation directly affected by air temperature and it at 100 cm has open-shaped small fluctuation. Underground temperature variation, a difference between high and low values, during monitoring period is weakly proportional to hydraulic conductivity of the sediment and it is assumed that water plays a part in delivering air temperature in soil. The underground temperature estimated by a numerical model is very similar to the observed data with an average value of 0.99 cross-correlation coefficient. From the result of this study, the aquifer unsaturated hydraulic conductivity of the soil and the groundwater recharge is likely to be able to estimate with underground temperature profile calculated using a numerical model.

Cause of Corrosion and Evaluation of Material Corrosion Resistance on Underground Heat Transport Facilities Connected to Manhole (맨홀과 연결된 지하 열수송설비의 부식 원인 및 재질 내식성 평가)

  • Song, M.J.;Choi, G.;Kim, W.C.;Lee, S.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.35 no.4
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    • pp.193-202
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    • 2022
  • Manholes and underground spaces are installed to manage the buried heat transport pipes of the district heating system, and the corrosion damage of the equipment placed in this space often occurs. The purpose of this work is to identify locations with a high risk of corrosion damage in the air vent and to establish preventive measures based on precise analysis via sampling of heat transport pipes and air vents that have been used for about 30 years. The residual thickness of the air vent decreased significantly by reaching ~1.1 mm in thickness, and locations of 60~70 mm away from a transport pipe were the most vulnerable to corrosion. The energy dispersive X-ray spectroscopy (EDS) analysis was performed in the corroded oxides, and it was found that chloride ion was contained in the corrosion products. Anodic polarization tests were carried out on the air vent materials (SPPS250, SS304) with varying the amounts of chloride ions at two different temperatures (RT, 80℃). The higher concentration of chloride ions and temperature are, the lower corrosion resistances of both alloys are.

The Air-stripping Process Conjugated with the Ultrasonic Treatment to Remove TOC in Groundwater around the LPG Underground Storage Cavern (탈기법과 초음파 처리법을 연계한 LPG 지하공동저장소 주변 오염지하수 내 TOC 제거)

  • Han, Yikyeong;Jun, Seongchun;Kim, Danu;Jeon, Soyoung;Lee, Minhee
    • Economic and Environmental Geology
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    • v.55 no.5
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    • pp.511-519
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    • 2022
  • In order to develop an air-stripping based remediation process to remove the TOC (Total Organic Carbon) in groundwater around the underground LPG storage cavern, the laboratory scale experiments at various conditions (change of air injection volume and temperature, the application of ultrasonic treatment, etc.) for two types of groundwater (initial TOC concentration of 608 mg/L and 153 mg/L, respectively). From results of experiment, as the air injection rate for stripping into groundwater increased from 2 L/min to 11 L/min and as the air-stripping time increased from 1 hour to 24 hour, the TOC removal efficiency of air-stripping increased. However, the TOC concentration of treated groundwater was higher than the discharge tolerance limit (100 mg/L) even after 24 hour stripping at the maximum air injection rate of 11 L/min. The main compounds of the TOC in groundwater were identified as methanol and propane and the long stripping time (more than 24 hour) was needed to separate the methanol from groundwater because of the affinity between water and methanol. At 20℃ and 4 L/min of air injection, the TOC removal efficiency increased to 59.1% after 24 hour air-stripping. When the temperature of groundwater increased to 30℃ and 40℃, the TOC removal efficiency increased up to 80.0% and 82.8%, suggesting that more than 24 hour air-stripping at 40℃ is needed to lower the TOC concentration to below 100 mg/L and the additional TOC removal process as well as the air-stripping is necessary. When the temperature increased to 60℃ and the ultrasonic treatment was conjugated with the air-stripping, the TOC removal efficiency increased to 87.8% within 5 hour stripping and the final TOC concentration (72.4 mg/L) was satisfied with the TOC discharge tolerance limit. The TOC removal efficiency for groundwater having low TOC concentration (153 mg/L) also showed similar removal efficiency of 89.7% (the final TOC concentration: 18.9 mg/L). Results in this study supported that the air-stripping conjugated with the ultrasonic treatment could remove successfully the TOC in groundwater around the underground LPG strorage cavern.

The Size-Oriented Particulate Mass Ratios and Their Characteristics on the Seoul Metropolitan Subway Lines

  • Lee, Eun-Sun;Lee, Tae-Jung;Park, Min-Bin;Park, Duckshin;Kim, Shin-Do;Kim, Dong-Sool
    • Asian Journal of Atmospheric Environment
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    • v.10 no.4
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    • pp.217-225
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    • 2016
  • The purpose of the study was to initially investigate the concentration patterns of $PM_1$, $PM_{2.5}$ and $PM_{10}$ in the Seoul subway lines, and then to figure out the PM behaviors of internal and external sources inside subway tunnels. The PMs were monitored by a light scattering real-time monitor during winter (Jan. 8-26 in 2015) and summer (July 2-Aug. 7 in 2015) in tunnel air, in passenger cabin air, and in the ambient air. The daily average $PM_{10}$, $PM_{2.5}$, and $PM_1$ concentrations on these object lines were $101.3{\pm}38.4$, $81.5{\pm}30.2$, and $59.7{\pm}19.9{\mu}g/m^3$, respectively. On an average, the PM concentration was about 1.2 times higher in winter than in summer and about 1.5 times higher in underground tunnel sections than in ground sections. In this study, we also calculated extensively the average PM mass ratios for $PM_{2.5}/PM_{10}$, $PM_1/PM_{10}$, and $PM_1/PM_{2.5}$; for example, the range of $PM_{2.5}/PM_{10}$ ratio in tunnel air was 0.82-0.86 in underground tunnel air, while that was 0.48-0.68 in outdoor ground air. The ratio was much higher in tunnel air than in outdoor air and was always higher in summer than in winter in case of outdoor air. It seemed from the results that the in/out air quality as well as a proper amount of subway ventilation must be significant influence factors in terms of fine PM management and control for the tunnel air quality improvement.