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Sung-Soo Cha Kang-Kun Lee Gwang-Ok Bae Dae-Hyuck Lee Nicolas Gatelier 《Engineering Geology》2007,93(3-4):117-129
Hydrogeological monitoring was conducted around a pilot cavern for underground cryogenic LNG (Liquefied Natural Gas) storage. The monitoring was mainly focused on the operation of a drainage and recharge system. After the operation of the drainage system commenced, the drainage rate decreased rapidly in the initial stages and then decreased gradually. Hydrogeological monitoring revealed that the rock drainage system operated effectively. During drainage, the water table was maintained below the cavern roof. The recharge for ice-ring formation was performed in two phases. The first phase involved the cessation of pumping in downward-drainage holes and the second involved the closure of upward boreholes. Since the water table was maintained below the cavern roof, artificial recharge was planned at first. However, it was not implemented due to heavy rainfall in the recharge stage. On the basis of hydrogeological monitoring and hydraulic tests, it was found that the fractures above the roof and on the right wall of the pilot cavern mainly affected seepage into the cavern and thermal variation due to the storage of liquid nitrogen. Thermal variation was examined by the thermometers installed around the pilot cavern. The cooling and thawing processes reveal the characteristics of thermal distribution in the rock and the 0 °C isotherm. The cooling phase lasted for six months, and the 0 °C isotherm progressed in time after the injection of liquid nitrogen into the cavern. The isotherm propagated up to about 4 m from the floor and the sidewall of the cavern and about 3 m from the cavern roof. The cooling rate of the rock mass above the cavern roof was lower than that of the other cavern sides due to the gaseous space in the upper part of the containment. The fractures were analyzed and considered for thermal modeling. A two-dimensional finite element analysis was performed to compare the field monitoring at the pilot cavern. The numerical modeling shows the distance between the ice ring and heat transfer pattern of the fractures around the pilot cavern. The propagation of the measured and calculated 0 °C isotherm reveals that the water-conveying joint on the right wall might affect thermal propagation through a thermal pipe. 相似文献
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General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structures have diverse variables, studies to assess behaviors resulting from various variables are continuously required to supplement the imperfections related to such variables. In the present study, materials elastic modulus and yield strength were selected as variables for strength that would be applied to diagrid structural systems in the form of Twisters among the irregular shaped buildings classified by Vollers and that affect the structural design of these structural systems. The purpose of this study is to conduct sensitivity analysis for axial rotation diagrid structural systems according to changes in brace angles in order to identify the design variables that have relatively larger effects and the tendencies of the sensitivity of the structures according to changes in brace angles and axial rotation angles. 相似文献
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Northward shifts due to global warming are apparent in various organisms in the Northern Hemisphere such as insects, fish, birds, and plants. However, these findings were mainly reported in Europe and North America. Therefore, such range shifts should be examined in other regions such as Asia to confirm global northward shifts in the Northern Hemisphere. In South Korea, we tested whether the distribution margins of Korean butterflies shifted northward or southward. We used occurrence data from two Korean butterfly atlases (1938-1950 and 1996-2011). The margin (northern or southern) shifts were evaluated using both latitudinal shifts of margin records (direct evaluation) and the intercept shift in the regression equation between the margin shift and the change in occurrence (intercept evaluation). Northern margins of southern species shifted northwards, whereas southern margins of northern species shifted southwards due to habitat enlargement (national reforestation in South Korea). The annual northward shift of northern margins of 10 Korean southern species was 1.6 km for 60 years, which is similar to the Korean isothermal shift (1.5 km per year). 相似文献
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Local Meteorological and Synoptic Characteristics of Fogs Formed over Incheon International Airport in the West Coast of Korea 总被引：2，自引：0，他引：2
Fogs observed over Incheon international airport (IIA) in the west
coast of Korea from January 2002 to August 2006 are classified into categories
of coastal fog, cold sea fog, and warm sea fog based on the areal extent of the
fogs and the difference between the air temperature (T) and the SST, i.e.,
cold sea fog if TSST = T-SST>0oC and warm sea fog if TSST
<0oC. The numbers of coastal, cold, and warm sea fog cases
are 64, 26, and 9. Coastal fogs form most frequently in winter, while cold sea
fogs occur mostly in summer and warm sea fogs are observed from January to May
but not in November and December. On average the air gets colder by
1.6oC during the three hours leading up to the coastal fog
formation, and an additional cooling of 1.1oC occurs during the
fog. The change in the dew point temperature (Td) is minimal except
during the fog (0.6oC). Decreases in T for the cold and warm
sea fogs are relatively smaller. The average Td is higher than SST
during the cold sea fog periods but this Td is more than
4oC higher than that for the corresponding non-fog days,
suggesting that cold sea fogs be formed by the cooling of already humid air
(i.e., Td>SST). Increases of Td are significant during the
warm sea fog periods (1.4oC), implying that efficient moisture
supply is essential to warm sea fog formation. Four major synoptic patterns are
identified in association with the observed fogs. The most frequent is a north
Pacific high that accounts for 38% of cases. Surface or upper inversions are
present in 77%, 69%, and 81% of the fog periods for coastal, cold, and
warm sea fogs, respectively. 相似文献
5.
Sung-Soo Cha Jin-Yong Lee Dae-Hyuck Lee Eric Amantini Kang-Kun Lee 《Engineering Geology》2006,84(3-4):229-243
Feasibility of storing LNG in a lined rock cavern was evaluated using a pilot cryogenic rock cavern constructed in Daejeon, Korea. The pilot program included hydrogeological and engineering characterization of the rock mass around the cavern, design and construction of a drainage system, and pilot operation of the cryogenic cavern. An appropriate drainage system is most important to protect the containment system of LNG from thermal shocks due to ice lenses and hydrostatic pressure of groundwater. As a part of the pilot program, this study focused on the evaluation of hydraulic and engineering properties of the rock mass around the cavern. For this purpose, engineering logging of the rock cores, single and cross-hole hydraulic tests, and recharge/drainage tests were performed using seven drilled holes with different trends and plunges. Three main joint sets were found from the logging of the rock cores, acoustic borehole televiewer, and window mapping. The orientations of the three major joint sets were 60/209, 40/171, and 29/331, which can provide the main groundwater flow paths. Mean RQD values ranged from 56 to 88, which were classified as fair and good, although varying with depth along single boreholes. Hydraulic conductivity from the single and cross-hole hydraulic tests estimated in the order of 10−6 or 10−7 m/s and corresponding transmissivity ranged between 10−5 and 10−6 m2/s. Permeable intervals identified from the hydraulic tests were mostly located above the cavern roof. Below the roof, the permeable zone was difficult to observe. According to the hydraulic communication tests performed for some designated intervals, hydraulic connection between boreholes was highly varied with depth or location, which indicated a very different distribution of water conducting joint sets along the boreholes. When water was injected at R1 with constant or varying flow rates, monotonous and stable seepage was observed at observation boreholes. From this, some stable drainage was expected even in relatively heavy rainfalls. When designing the drainage system of the cavern, the drainage holes should be orientated to maximize frequency of encountering the major joint sets and the permeable intervals identified from this study. 相似文献
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Myoung-Joo LEE Ki-Ho CHANG Gyun-Myoung PARK Jin-Yim JEONG Ha-Young YANG Ki-Deok JEONG Joo-Wan CHA Sung-Soo YUM Jae-Cheol NAM Kyungsik KIM Byung-Chul CHOI 《大气科学进展》2009,26(2):222-228
The snow enhancement experiments, carried out by injecting AgI and water vapor into orographically enhanced clouds (fog), have been conducted to confirm Li and Pitter’s forced condensation process in a natural situation. Nine ground-based experiments have been conducted at Daegwallyeong in the Taebaek Mountains for the easterly foggy days from January–February 2006. We then obtained the optimized condi- tions for the Daegwallyeong region as follows: the small seeding rate (1.04 g min-1) of AgI for the easte... 相似文献
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Maritime/continental microphysical contrasts in stratus 总被引：5，自引：0，他引：5
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云滴谱宽度对模式中云的光学厚度的参数化、气溶胶间接效应的评估以及降水形成过程的研究至关重要。本文利用美国POST（Physics of Stratocumulus Top）项目2008年7月19日的飞机观测资料，分析了微物理量和云滴谱的垂直分布及微物理过程。结果表明，该云系云滴谱宽度在云底附近较大，这是由低层核化过程导致的；中层凝结增长过程使得云滴谱宽度随高度增加逐渐减小；云顶附近夹卷混合过程导致云滴谱宽度增大。绝热云中垂直速度的增大会促进云凝结核的活化使云滴数浓度增大，促进凝结增长使云滴尺度增大、云滴谱宽度减小，云滴谱宽度与云滴数浓度、云滴尺度呈现负相关关系；云洞中受夹卷混合过程影响，垂直速度减小，云滴蒸发，云滴数浓度和云滴尺度减小、云滴谱宽度增大，且该效应随绝热程度减小而增强。建议云滴谱宽度的参数化将垂直速度、云滴数浓度、云滴尺度和绝热程度等考虑在内。 相似文献
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