• Korean Journal of Heritage: History & Science
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• v.52 no.4
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• pp.264-271
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• 2019

Cheomseongdae in Gyeongju, known as an astronomical observatory, is a cultural monument with great historical, academic, and artistic value, as its unique shape is preserved well in its original form. The outer structure, ground stability, and seismic reliability of Cheomseongdae have been assessed by numerous researchers through various scientific methods, but research on the underground structure has been insufficient. This paper contains detailed models of the underground structure of Cheomseongdae interpreted in 2D and 3D images based on the data acquired through GPR surveys conducted of features in and around the base of Cheomseongdae. As a result, the existence of twelve small features arranged in a circle, although only about half of them remain, was confirmed at a depth of 0.4 - 0.6m. Furthermore, a structure three bays long (north-south direction) and four bays wide (east-west direction) was detected beneath Cheomseongdae at the depth of 0.7 - 1.0m. Other than 2 layers of foundations as is known, a square structure with the dimensions of 7m × 7m is situated at a depth of 0.6m, directly under Cheomseongdae, and what is reading that is expected to be the foundation structure of Cheomseongdae was detected and confirmed. This foundation structure is circular with a diameter in the east-west direction of 11m and in the north-south direction of 12m. The northern, western, and eastern edges of this foundation structure are about 1m away from the foundation of Cheomseongdae, whereas the the south side extends to about 5m wide.

• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.95-102
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• 2014

There are a variety of structures below the surface are buried. In particular, if It is experiencing problems in the city gas pipe or electrical wire, our safety would be greatly jeopardized. Therefore, the underground structures which encounter a variety of pollutants are highly sensitive to corrosion. So if you are not identify the degree of corrosion, it can lead to large accidents such as gas leakage. Until now, person visit directly every underground structure to measure and record manually, but This approach requires a lot of human and material resources and the continuity of management. Therefore, the research to find out the risk factors quickly via the continuous management is needed, and in this paper the structures management systems in the vehicle being moved by combining ICT underground structures for state information wirelessly collects and analyzes system is proposed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.4
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• pp.323-333
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• 2005

Recently the fire is happening at the tunnel and underground - structure internationally. We are socially the economy the actual circumstances which serious loss is happening due to an fire occurrence when fire happened which is closed like tunnel and underground - structure, the collapse from the burglar degradation of strength of tunnel concrete lining and human life damage happen. It causes big problem while the long time disconnects a traffic network. While the fire happened in this research at the tunnel, the paper construct a basis data to deduce the specification regulation about stability of tunnel concrete lining. In this paper, the experiment was carried out for the prevention of explosive spalling of tunnel to use a reinforced Polypropylene concrete which mixes a Polypropylene which are known for the thing by being efficient at a protect of explosive spalling of the concrete. According to the firproof test result of reinforced Polypropylene admixture mortar, Polypropylene admixture of prevention of explosive spalling analyzed 0.2%-0.25%.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.43-53
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• 2004

In this study, scaled-model tests were performed to investigate the effect of underground openings on the stability of surface structure around the abandoned coal mine areas. Four types of test models which had respectively different depths of openings and different ground reinforcement conditions were introduced, where the modelling materials were the mixture of sand, plaster and water. The model with deep openings were turned out more stable to the structure than the model with shallow ones, because the crack-initiating pressure of the former was 2.5 times as much as that of the latter. The models with ground reinforcement were also fumed out more stable than the model without reinforcement, because the crack-initiating pressure of the former was 2.4 times as much as that of the latter. Subsidence profiles were analysed to find the characteristics of slope and curvature, and the model with large reinforcement were turned out the most stable.

• International Journal of Highway Engineering
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• v.5 no.2 s.16
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• pp.25-35
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• 2003

During construction of circular lifeline pipe, the non-proper compaction along the pipe and the decrease of compaction efficiency are the main problems to induce the failure of underground pipe. The use of CLSM(controlled low strength materials) is one of the applications to overcome those problems. In this research, the numerical analysis by PENTAGON FEM program was carried out for 20 cases with the couple of combinations on bedding materials, backfill materials, and pipes. From the FEM analysis, the use of CLSM as backfill materials reduced the settlement of ground surface and the deformation of pipe employed. In case of the vertical deformation on the pipe, common soil backfill for flexible pipes showed 2 times for rigid pipes, but CLSM backfill case did less deformation than the soil backfill for rigid pipes. CLSM backfills for rigid pipes showed the similar results. Judging from the FEM analysis, the use of CLSM increases the structure capacity of the underground pipes.

• Tunnel and Underground Space
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• v.18 no.2
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• pp.125-133
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• 2008

The rock treatment methods for improving bearing capacity and reducing settlement of the underground roadway structure foundation on fractured rock was studied in this paper. Also, effective reinforcement scheme was evaluated by numerical analysis for the application to the practical construction. Various in-situ and laboratory tests were executed systematically at Yeongi-goon, Ohoongchungnam-do, Korea, for the purpose of defining the physical and mechanical properties of rock. Consequently the effective treatment methods insuring the bearing capacity of fractured rock were proposed. In addition, the adequate reinforcing depth of the comparatives measure, such as double rod, triple rod injection methods and micropile, were investigated from the case study. Finally, the most effective construction scheme with the consideration of safety and economical aspects were proposed by using numerical analysis(Plaxis ver. 8.2).

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1306-1312
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• 2011

Underground Subway station's air pollutants are introduced from the indoor or outdoor. And Radon is a major pollutant in the subway station. Radioactive substances Radon is occuring naturally in granite tunnel wall and underground water. Especially inert gas Radon that causes lung cancer in human is anywhere but 5678 S.M.R.T. tunnels deep and pass through the granite plaque have a lot of Radon. The Radon concentration is determined by the following reasons : radon content of soil and concrete, underground water, ventilation, pressure difference, building structure, temperature, etc. So Radon concentration is hard to predict. And we can't only ventilate owing to era of high oil prices. This study focuses on our efforts for the reduction of Radon concentration. And the purpose is to provide basically datas of specially managed 15 subway station's Radon concentration.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.470-471
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• 2008

SVL is installed at underground transmission system to protect cables and insulation joint-box from overvoltages caused by lightning, switching, and line-to-ground fault. Domestic underground power system adopts cross bonding type to reduce the induced voltage at sheath, but single-point bonding is required depending the system installation configuration. SVL can be easily broken by overvoltages induced at joint-box because single-point bonding has uneffective system structure to extract fault current. ANSI/IEEE recommends Parallel Ground Continuity Conductor(PGCC) to prevent SVL breakdown. In this paper, EMTP simulation is performed to analyze effects on SVL under PGCC installation when single-line-to-ground fault occurs. The result shows that PGCC and short single-point bonding distance can reduce overvoltages at SVL.

• Tunnel and Underground Space
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• v.15 no.5 s.58
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• pp.352-358
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• 2005

For non-destructive testing of concrete structures, time and frequency domain method were applied to detect cavity in underground model and pier model. To interpret the measured data, time domain method made use of tomography which was completed with first arrivaltime and inversion method. In this steady, frequency domain method using Fourier transform was tried. Maximum frequency in the frequency domain was analyzed to calculate location of cavity.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.37-40
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• 2007

As a demand for underground structure is increasing with more parking and retail spaces required. Various construction methods are reviewed and selected for each specific site for economical and fast construction. In this study, factors for selecting construction methods were categorized for substructure construction. Construction processes of substructure are consisted of methods for excavation, earth retaining systems, and placement of slabs. Factors for the selection of substructure construction method are the condition of surrounding, geotechnical, information and constraint by comfortness for others nearby. After survey for the construction data of 5 different sites, analysis about reliable substructure construction selection method was suggested.