• Tunnel and Underground Space
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• v.11 no.4
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• pp.339-343
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• 2001

Shield tunnel having circular section located in the soil or soft rock layer is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately during earthquakes. Based on this knowledge, the ground-tunnel interaction effect for this particular vibration mode is investigated. The ground surrounding a tunnel is assumed to be a homogeneous elastic medium. The bonded boundary condition on the ground-tunnel interface is considered. This suggests a firm bond between the ground and the tunnel lining. As Poisson's ratio and stiffness of the ground increases, the strain induced within the tunnel lining increases.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.55-72
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• 2018

A method that can predict the mixed-ground condition ahead of a TBM tunnel face during tunnel construction utilizing electrical resistivity and induced polarization (IP) was proposed in this study. Effect of TBM advancement approaching the mixed-ground condition (composed of soil layer overlying rock layer) when currently running through soil zone on the electrical resistivity and IP measuring was assessed with laboratory-scale experiments. The resistivity and IP values were measured using four electrodes, by installing two electrodes on the tunnel face (at the cutterhead), and the other two electrodes on the segment lining. The test results showed that both of the measured resistivity and IP values were kept increasing as the TBM is approaching the soil-rock mixed-ground. Also, to get the more reliable results for predicting the mixed-ground condition, it was recommended that the measurement is made at the tunnel face utilizing 4-electrodes installed at the cutterhead as well as it is made utilizing the 2-electrodes installed at the segment lining along with the 2-electrodes installed on the tunnel face (at the cutterhead) so that two measured results are compared each other.

• Journal of the Korean Geotechnical Society
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• v.34 no.12
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• pp.19-27
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• 2018

Terzaghi proposed a 2D formula for arching based on the assumption of a vertical sliding surface induced in the upper part due to the downward movement of a trapdoor. The formula was later expanded to consider 3D tunnel excavation conditions under inclined sliding surfaces. This study further extends the expanded formula to consider the effects of different ground properties and inclined sliding conditions in the transverse and longitudinal directions considering anisotropic ground conditions, as well as 3D tunnel excavation conditions. The 3D formula proposed in this study was examined of the induced vertical stress under various conditions (ground property, inclined sliding surface, excavation condition, surcharge pressure, earth pressure coefficient) and compared with the 2D Terzaghi formula. The examination indicated that the induced vertical stress increased as the excavation width and length increased, the inclination angle increased, the cohesion and friction angle decreased, the earth pressure coefficient decreased, and the surcharge pressure increased. Under the conditions examined, the stress was more affected at low excavation lengths and by the ground properties in the transverse direction. In addition, The comparison with the 2D Terzaghi formula showed that the induced vertical stress was lower and the difference was highly affected by the ground properties, inclined sliding conditions, and 3D tunnel excavation conditions. The proposed 3D arching formula could help to provide better understanding of complex arching phenomena in tunnel construction.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.233-240
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• 2003

A GIS-based tunnelling risk management system (GIS-TURIMS) has been developed in this study The developed system uses ArcView 8.2 as a basic platform and the built-in interface(VBA) has been used to perform first-order simplified analyses for prediction of tunnelling-induced ground movements and building damage assessment. The main emphasis in this study was to develop a working framework that can be used in the perspective of tunnelling risk management. The developed system is capable of carrying out computationally intensive first-order analyses for ground movement prediction as well as building/utilities damage assessment with fully taking advantage of the GIS technologies. This paper describes the concept and details of the GIS-TURIMS development and implementation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.88-95
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• 2007

Generally, the integrated system using ion beam consists of 4 major parts, which are SEM, FIB, nano stage, and chamber. Among them, the nano stage and the chamber are designed and manufactured. The whole systems are integrated. Also, FE models are built to perform modal analyses of each part and the whole integrated system with a commercial program. Through these analyses, it is found that each part and the integrated system are very safe against vibrations including external excitations from ground and any others, because their natural frequencies are much larger than frequencies of external excitations. Also, isolation of ground induced vibration is considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.365-370
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• 1998

In this study, the method of analysis which is developed for calculating dynamic train loads and ground vibration by Shin-Chu Yang is verified comparing measurements of real structure. The results of analysis are agreed well with measurements of ground and structural vibration induced by passing train. The vibration level of analyzed results which is more than that of measured gives conservative result. To analyze frequency characteristics, the analyzed results are applied to the ISO environmental vibration regulation and reveal the possibility of application in analysis of frequency characteristics.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1659-1662
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• 1998

This paper is to analyze electromagnetic fields on a 154kV substation system and induced voltages on the substation fence when the network is operating in a normal condition or a fault condition in which one phase is shorted with the overhead ground wire. Also, changing the scalar potential and electromagnetic fields that are changed in accordance with changing resistivity and permeability of ground are studied. A finding of the study is that the scalar potential and electromagnetic fields are raised near the tower: The values of electric field on the corner of fence and at the edge of the ground grid are higher than other locations.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.311-318
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• 2002

A GIS-based tunnelling risk management system (GIS-TURIMS) has been developed in this study, The developed system uses ArcView 8.2 as a basic platform and the built-in interface (VBA) has been used to perform first-order simplified analyses for prediction of tunnelling-induced ground movements and building damage assessment. The main emphasis in this study was to develop a working framework that can be used in the perspective of tunnelling risk management. The developed system is capable of carrying out computationally intensive analyses for ground movement prediction as well as building/utilities damage assessment with fully taking advantage of the GIS technologies. This paper describes the concept and details of the GIS-TURIMS development and implementation

• Structural Engineering and Mechanics
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• v.6 no.3
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• pp.347-362
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• 1998

In this study an improved design method for the traditional A-type(or V-type) offshore template platform system was proposed to mitigate the vibration induced by the marine environmental loadings and the strong ground motions of earthquakes. A newly developed material model was combined into the structural system and then a nonlinear dynamic analysis in the time domain was carried out. The analysis was focused on the displacement and rotation induced by the input wave forces and ground motions, and the mitigation effect for these responses was evaluated when the viscoelastic damping devices were applied. The wave forces exerted on the offshore structures are based on Stokes fifth-order wave theory and Morison equation for small body. A step by step integration method was modified and used in the nonlinear analysis. It was found that the new design approach enhanced with viscoelastic dampers was efficient on the vibration mitigation for the structural system subjected to both the wave motion and the strong ground motion.

• Explosives and Blasting
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• v.23 no.3
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• pp.1-10
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• 2005

Blast-induced ground vibration nay cause an environmental impact such as neighbour's complaints or damage on adjacent structures and facilities. Complaints associated with blasting have often become a target of public grievances. One of the difficulties to solve the problem is that we do not have a national standard for the acceptance level of blast-induced ground vibration. A peak particle velocity criterion, which was suggested for urbane underground construction, has often been widely used. Efforts have been made to establish more rational criteria. It seems that differing cultures have often differing thresholds of the toleration of vibration, and that technical data or rational grounds for establishing the limits are hardly provided. In this paper, national standards for allowable limit of blast vibration were presented and discussed.