• Journal of KSNVE
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• v.8 no.1
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• pp.187-194
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• 1998

In order to predict the train noise propagation from a level railroad, this paper presents the model of train noise source and the prediction model based on the results by using the sound intensity method. The prediction model gives the effects of geometric attenuation, ground attenuation, and barrier attenuation of noise. There are several principal assumption in developing model: (a) the train noise is primarily rolling noise; (b) the rail head and wheels are in good condition; (c) the height of source is 10cm above track; (d) the directivity pattern of train noise sources is a dipole source. Calculated results based on this model are compared with available field data and good agreement has been obtained.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.85-95
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• 2007

In this study, in order to propose the prediction method of the residual settlement of clayey ground improved by vertical drains, a series of numerical analyses for a model ground were carried out using the elasto-viscous consolidation model. And the effects of ground improvement conditions of the ratio of effective radii $(r_e/r_w)$, consolidation pressure $({\Delta}p)$ on normally consolidated state, and the OCR (overconsolidation ratio) on overconsolidated state to reduce the residual settlement in three-dimensional consolidation by vertical drains were investigated by performing a series of numerical analyses. Furthermore, based on the results of a series of numerical analyses for the model ground, the predicting method of the residual settlement of clayey ground with vertical drains and the determination method of the value of OCR required to control the residual settlement within an acceptable value are proposed.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.2
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• pp.37-44
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• 2008

A theoretical equation was proposed to consider the effect of ponding for the excess pore water pressure in agricultural reservoir on soft clay ground. The value of excess pore water pressure predicted using the proposed equation was compared to those predicted with the Terzaghi's method and the finite difference method(FDM), respectively, for the purpose of verification. The degree of consolidation according to ponding predicted by applying the proposed equation was close to the observed degree of consolidation on the double drainage condition(at DP-3) but it was less than the observed degree of consolidation on the single drainage condition(at DP-5). The equation was very applicable to practice because the analysis result by the equation was close to the observed data.

• Tunnel and Underground Space
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• v.13 no.6
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• pp.476-485
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• 2003

The purpose of this study is to present an analysis method for the prediction of the change of ground conditions. To this end, three-dimensional convergence displacements is analyzed in several ways to estimate the trend of displacement change. Three-dimensional arching effect is occurred around the unsupported excavation surface including tunnel face when a tunnel is excavated in a stable rock mass. If the ground condition ahead of tunnel face changes or a weak fracture zone exists a specific trend of displacement change is known to be occurred from the results of the existing researches. The existence of a discontinuity, whose change in front of the tunnel face, can be predicted from the ratio of L/C (longitudinal displacement at crown divided by settlement at crown) etc. Therefore, the change of ground condition and the existence of a fracture zone ahead of tunnel face can be predicted by monitoring three-dimensional absolute displacements during excavation, and applying the methodology presented in this study.

• Journal of the Korean GEO-environmental Society
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• v.19 no.3
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• pp.35-45
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• 2018

It is essential to predict ground conditions ahead of the tunnel face during tunnel excavation. Various studies on tunnel prediction method of the ground condition ahead of the tunnel face have already been done and applied to in mechanized tunnelling job sites. So, all the methods used in mechanized tunnelling to predict ground conditions ahead of the tunnel face were reviewed. A questionnaire surveying Tunnel Boring Machine (TBM) operators with at least 10 years' experience in TBM operation was used to determine the requirements for prediction methods as well as the distance from the tunnel face that must be assessed. Based on the result of questionnaire survey, the most feasible prediction methods applicable to mechanized tunnelling job-sites are suggested. One of the prediction methods applicable to mechanized tunnelling job-sites might be the electrical resistivity survey by utilizing the disk cutter on the cutterhead as electrode. So, in this study, laboratory tests were performed to evaluate the feasibility of prediction method utilizing electrical resistivity survey at mechanized tunnelling job-sites. It was found that geological condition ahead of 0.3 times of TBM's diameter from tunnel face could be predicted.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.1-11
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• 2020

In this study, study on the internal ballistic analysis method for single-chamber dual-thrust rocket motors meeting a dual-thrust profile requirement by tailoring the grain burning area is presented. The analysis method, which can acquire variables required for the performance prediction, considering gradual change of burning rate correction factor and specific impulse in the transition phase, is proposed. Improvements compared to the analysis method in the previous study, which do not consider change in the transition phase, are verified through comparison between the newly proposed method and the method in the previous study. Internal ballistic variables are obtained for four different ground firing test conditions using the proposed method, and the performance prediction for each condition is conducted using these variables. These prediction results and the ground test data are in good agreement, so it is confirmed that the performance prediction of dual-thrust motors with same design geometries based on the proposed analysis method is available.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1348-1357
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• 2006

For the rational aseismatic design of a structure constructed on the ground which has weakness for liquefaction or flow, it is necessary to predict ground deformation as well as force acting on the ground. In general, the prediction of liquefaction is based on solid mechanics while the prediction of flow is basis of fluid mechanics. Since liquefaction and flow occur continuously, unified analysis methods have been developed. Among of them is Rue-elasto plastic model that is based on small deformation theory. This methods, however, is not adequate for such a large deformable ground condition. In this paper, a large deformaion theory using the finite deformation theory proposed by Dietal and the updated lagrangian method is presented. In addition, the applicability of the theory is verified by 1-d consolidation analysis and flow tests.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.2
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• pp.227-242
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• 2019

This paper presents a method to predict ground types ahead of a tunnel face utilizing operational data of the earth pressure-balanced (EPB) shield tunnel boring machine (TBM) when running through soil ground. The time series analysis model which was applicable to predict the mixed ground composed of soils and rocks was modified to be applicable to soil tunnels. Using the modified model, the feasibility on the choice of the soil conditioning materials dependent upon soil types was studied. To do this, a self-organizing map (SOM) clustering was performed. Firstly, it was confirmed that the ground types should be classified based on the percentage of 35% passing through the #200 sieve. Then, the possibility of predicting the ground types by employing the modified model, in which the TBM operational data were analyzed, was studied. The efficacy of the modified model is demonstrated by its 98% accuracy in predicting ground types ten rings ahead of the tunnel face. Especially, the average prediction accuracy was approximately 93% in areas where ground type variations occur.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.479-489
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• 2009

Appropriate investigation of ground condition near excavation face in tunnelling is an inevitable process for safe and economical construction. In this study mechanical parameters from drilling process for blasting were investigated for the purpose of predicting the ground condition, especially rock mass strength, ahead of tunnel face. Rock mass strength is one of the most important factors for classification of rock mass and making a decision of support type in underground construction. Several rock specimens which are considered homogeneous and having different strength values respectively were tested by hydraulic drill machines generally used. As a result, penetration rate is fairly related with rock mass strength among drilling parameters. It is also found that penetration rate increases along with the higher impact pressure even under same rock strength condition. It is finally suggested that new prediction method for rock mass strength using percussive pressure and penetration rate during drilling work can be utilized well in construction site.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.914-921
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• 2010

When industrial structures are constructed on soft ground, ground subsidence is occurred by problems of bearing capacity. To protect ground subsidence have to improve soft ground, and have to predict settlement estimation for reasonable construction. Artificial Neural Networks(ANN) is adopted for prediction of settlement of construction during the initial design. In the study, Artificial Neural Networks are applied to predict the settlement estimation of initial condition ground and ground improved by D.C.M method. Also, this study compares results of Artificial Neural Networks and results of continuum analysis using Mohr-Coulomb models. In result, settlements of initial condition ground decreased over 0.7 times. Also, by comparing ANN and continuum analysis, coefficient of determination was comparatively high value 0.79. Thought this study, it was confirmed that settlements of improvement ground is predicted using laboratory experiment data.