• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.775-782
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• 2004

Recently, the cases which are constructed close by neighboring structure or underground structure are on the increase to get the utmost out of the land exploitation of underground space in the downtown area. As the building becomes larger, the excavation depth is getting deep, and the excavation area is getting, wide too. These are frequent occasions that the application of Strut or Anchor method is difficult, because of site boundary, civil application and the ground condition. Therefore, to solve these problem, we analyze and compare design with measuring data, change the design factor and show the improvement of course through the application of self-supported diaphragm wall using counterfort technique which is a new method. It is expected to be a contribution to the suitable exploitation method of construction.

• ALGAE
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• v.21 no.1
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• pp.133-139
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• 2006

Outdoor cultivation of cyanobacterium Spirulina platensis was carried out for 40 days in a batch mode. A half concentration of the SOT based on the underground water was used as culture medium. Working volume was 5.7 tons with 0.2 m depth. During cultivation, mean water temperature, DO and light intensity were all in proper conditions for the S. platensis growth. The adjustment of pH to over 10 with Na2CO3 and addition of the 1.5% natural salt were very effective to delete contaminant organisms, Chlamydomonas moewusii and Chlorella minutissima occurred one after the other in the culture. The mean productivity of the biomass based on the dry cell weight from 14 to 25 days, after the contaminants were deleted, was 7.8 g ·m–2· d–1, which was relatively high productivity in that a half concentration of the SOT was used for the culture. Underground water used in the culture minimized contaminants invasion and addition of the 1.5% natural salt was effective to delete contaminants as well as acted as mineral supplement in outdoor cultivation of S. platensis. Harvesting using the floating activity of S. platensis was effective from mass floating in day time after overnight without agitation and illumination.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.1
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• pp.41-51
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• 2006

This paper concerns the effect of lining interface adherence on the lining's load carrying capacity. A series of reduced scale laboratory tests and finite element anlayses were carried out with the aim of gaining insight into the effect of shotcrete lining adherence on the load carrying capacity of double shell lining. The results indicated among other things that the load carrying capacity of a double shell tunnel is significantly affected by the adherence between layers. Also revealed was that for cases with low lining layer adherence stress concentration may occur due to relative movement between the lining layers with this trend being more pronounced with increasing tunnel cover depth. Practical implications from the results of this study are discussed in great detail.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.1
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• pp.51-69
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• 2011

This paper presents the effect of tunneling on bridge pile foundation being operated using three-dimensional numerical modeling. Also the parametric study on the depth of tunnel of which the diameter was 10 m was carried out in order to evaluate the behaviors of pile foundation due to the tunnel excavation. This paper expresses the changes of vertical and horizontal displacement, movement of soil and stress of the pile. Based on the results obtained from the numerical analysis some insights into the changes of pile foundation behaviors due to variations of tunneling location were mentioned and discussed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.531-555
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• 2011

This study aims to derive the statistical models for the estimation of the required specifications of a rock TBM as well as for its cutterhead design suitable for a given rock mass condition. From a series of multi-variate regression analysis of 871 TBM driving data and 51 linear rock cutting test results, the optimum models were newly proposed to consider a variety of rock properties and mechanical cutting conditions. When the derived models were applied to two domestic shield tunnels, their predictions of cutter penetration depth, cutter acting forces and cutter spacing were very close to real TBM driving data, showing their high applicability.

• Tunnel and Underground Space
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• v.1 no.2
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• pp.181-203
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• 1991

The effects of geologic structures such as rock joins and bedding planes on the thermal conductivity of a discontinuous rock mass are studied. The expressions for the equivalent thermal conductivities of jointed rock masses are derived and found to be anisotropic. The degree of anisotropy depends primarily on the thermal properties contrast between the joint phase and surrounding intact rock, the joint density expressed as volume fraction and the inclination angle of the joint. Within the context of 2-dimensional finite element heat transfer scheme, the isotherms around a circular hole are analyzed for both the isotropic and anisotropic rock masses in 3 different thermal boundary conditions. i.e. temperature, heat flux and convection boundary conditions. The temperature in the stratified anisotripic rock mass is greatly influenced by the thermal properties of the rock formation in contact with the heat source. Using the excavation-temperature coupled elastic plastic finite element method, analyzed is the thermo-mechanical stability of a circular opening subjected to 10$0^{\circ}C$ at a depth of 527m. It is found that the thermal stress concentration was enough to deteriorate the stability and form a plastic yield zone around the opening, in contrast to the safety factor greater than 2 resulted form the excavation-only analysis.

• Korean Journal of Artificial Intelligence
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• v.7 no.2
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• pp.1-8
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• 2019

This paper, we argue that sector in terms of the creative industries the need to the institutional settle of the rent-a-driver business; the industry could create more than 200,000 jobs, the effect is to bring out the about 4 trillion underground economy and Can be interpreted industry, which contributes to reduce social costs, ranging from 1.7 trillion won to 5.7 trillion per year. Through institutionalization of policy should support. Observation and in-depth interviews were conducted with the law and the president of the rent-a-driver business company. The operating system should be improved. the rent-a-driver business, for the formulation of the work ethic and education is desperately needed. The effect socio-economic contribution effect of the rent-a-driver business industry can be summarized as follows. First, it is an industry that has an operating system utilizing state-of-the-art technology and equipment, and the convergence of creative industries to comply with the market. Second, the effect appears as an industry that creates jobs for the populace to replace the social security system, social safety net is considered as an industry. Third, this is an industry that can be self-reliant in the short term at least political support, the industry is considered in the industry to maximize the effectiveness and efficiency of the support policy.

• Journal of the Society of Disaster Information
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• v.4 no.2
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• pp.138-154
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• 2008

The conventional non-dig underground structure building method which made an appearance to reduce the social and environmental costs and maximize the efficiency of the social overhead capital facilities could not help being uneconomical because of many problems such as unnecessary excessive excavation, water leakage, obstacle interference, difficulty of curvilinear application and connection complexity between propelled and injected bodies due to indiscriminate application of small and large circular steel pipes without consideration of the site conditions. The T.S.T.M, in which a protruded square tube is applied as a propulsion and injection body in a design that considered site conditions such as ground condition, depth of soil and live load, was able to be economical as it solved the problems of water resistance, minimization of obstacle interference and curvilinearity, and we can see that it can be applied to all grounds by utilizing or complementing the target ground in terms of engineering. Also in configuring the transverse section, it is possible to not only secure excellent structural safety but also implement all of the above engineering characteristics not only in the square cross section but also in the arch cross section, so it was possible to build structures on any section or ground, and we could confirm the LCC reduction effect and the VE effect.

• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.43-46
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• 2017

Recently, the development of underground space is being actively carried out in the urban area by saturation, and the excavation works are mainly carried out by various excavation methods by the structures adjacent to the ground and underground excavation. During such excavation work, ground subsidence accidents are occurring due to inattention construction, lack of construction technology, and leakage of ground water. For the prevention of ground subsidence we studied the method of risk influence factors by soil investigation. Analysis of 75 sites soil investigation by U.S.C.S (Unified Soil Classification System), construction method, depth of excavation and we studied the risk influence factors with ground subsidence.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.361-367
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• 2009

The criteria such as ASTM recommends that the zero reading process of CPT must be performed in the same temperature condition with underground in order to reduce the effect of temperature. However, this method can not consider the change of temperature occurred during penetration. In this study, ultra small size temperature sensor with 0.5mm in diameter is manufactured to estimate and compensate the effect of temperature by using FBG sensor. The continuous temperature changes are monitored during cone penetration by using FBG temperature sensor installed in cone penetrometer. The temperature compensated tip resistances show the uniform and similar distributions with depth in different with originally measured tip resistance in cohesive soil. This study verifies that the tip resistances measured by previous zero reading method are affected by the change of underground temperature, and suggests the new temperature compensation technique using by FBG temperature sensor.