• Proceedings of the Korean Geotechical Society Conference
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• 1990.10a
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• pp.25-34
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• 1990

For the construction of twin single track subway tunnels by NATM within close proximity of existing vehicle underpass in the highly congested area of downtown Seoul, finite element analyses were performed to evaluate the ground responses during tunnelling and also the stability and safety of the underpass structure and subway tunnels. Results of the analyses indicated the need to improve the soil beneath the underpass, and pre-grouting was carried out prior to the tunnel excavation. During tunnel construction field measurement program was implemented to confirm the results of anslyses and to control the tunnel construction procedures, thus ensuring stability of the existing structres.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.12a
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• pp.43-54
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• 1996

• Journal of Industrial Technology
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• v.26 no.B
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• pp.73-81
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• 2006

A sensitivity analysis about effects of influencing factors on the stability of Soil cut slope was performed. Slope stability analyses were carried out under dry, rainy and seismic conditions. Dominant factors controlling the slope stability were chosen such as cohesion and internal friction angle, unit weight of soil, water table and seismic horizontal coefficient used for the slope stability during earthquake. Parametric stability analysis with those factors was performed for sensitivity analysis. As results of analyzing the sensitivity of factors under dry and rainy conditions, effects of cohesion, internal friction angle and unit weight of soil on the stability of slope are more critical in the dry condition than in the rainy condition. Cohesion and internal friction angle are more dominant factors influencing the slope stability irrespective of dry or rainy conditions than unit weight of soil and the horizontal seismic coefficient. The unit weight and the horizontal seismic coefficient affects crucially the stability according to conditions of slope formation and dry or rainy seasons. For the effect of horizontal seismic coefficient on stability of slope, safety factor of slope is not affected significantly by dry or rainy conditions. However, increase of the horizontal seismic coefficient under the rainy condition floes reduce the safety factor significantly rather than the dry condition. Therefore, it is needed that the location of the water table is assigned appropriately to satisfy the required safety factor of stability in the case of checking slope stability for the rainy and seismic conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.811-818
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• 2005

Stability analyses on the 17 railroad cut-off soil slopes were carried out. The influences of rainfall infiltration on the slope stabilities were taken into account by seepage analyses using finite element method and by assuming ground water tables to be located adjacent to soil surface. The validity of those analyses were evaluated by comparing the slope failure characteristics between analysis results and the past failure records. The analyses were not appropriate to estimate the failure surface and the method considering only the increase of pore-water pressure (reduction of matric suction) as the influence of rainfall cannot appropriately estimate the surficial failures that occurred most of the cut-off soil slopes. For the better estimation of the surficial failure, the influence of water flows over slope surface which erode soil mass and/or increase driving force, should be evaluated and considered.

• Geomechanics and Engineering
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• v.28 no.1
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• pp.77-87
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• 2022

Many geotechnical analyses require the investigation of water flow within partially saturated soil zone to incorporate the effect of climatic conditions. It is widely understood that the hydraulic properties of the partially saturated soil should be included in the transient seepage analyses. However, the characteristics of dual porosity soils with dual-mode water retention curve are normally modelled using single-mode mathematical equation for simplification of the analysis. In reality, the rainwater flow can be affected significantly by the dual-mode hydraulic properties of the soil. This paper presents the variations of safety factor for dual porosity soil slope with dual-mode water retention curve and dual-mode unsaturated permeability. This paper includes the development of the new dual-mode unsaturated permeability to represent the characteristics of soil with the dual-mode water retention curve. The finite element analyses were conducted to examine the role of dual-mode water retention curve and dual-mode unsaturated permeability on the variations of safety factor under rainfall loading. The results indicate that the safety factor variations of dual porosity soil slope modelled using the dual-mode water retention curve and the unsaturated permeability equation are lower than those of dual porosity slope modelled using single-mode water retention curve and unsaturated permeability equations.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.199-206
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• 2005

Engineers have performed slope stability analyses, including Limit Equilibrium Analysis, Finite Difference Analysis and Finite Element Analysis. Each analysis results in different Factor of Safety(FS) for slopes. The comparison of FS results from these stability analyses has been carried out for various conditions, such as geometry of slopes, dry and fully saturated soils, nail and anchor reinforcements. Standard deviations of FS calculated from various slope analyses are 0.03 to 0.04 and 0.22 to 0.48 for the slopes without and with nail or anchor reinforcement, respectively. Construction of tiered concrete retaining wall in addition to nail or anchor reinforcement increases FS of 12% to 29% for fully saturated soils.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.125-131
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• 2021

For the vibration reliability tests, the jigs for mounting the test specimen on a vibration reliability tester are required. The dynamic stabilities of the jigs should be verified before the tests for obtaining the accurate reliability of the test specimen. This paper proposes an analytical technology for ensuring the dynamic structural stability for the test setup including the jig. The technology includes the mode analyses for checking resonance, the harmonic analyses for evaluating the dynamic structural stability of test setup including the jig, and the fatigue analyses for obtaining the durable reliability time with calculating the life cycles at the area of weakness. The cause investigation of the damaged jig during vibration reliability test of a rubber hose and the design of new revised jig are performed by using the technology. The vibration reliability test for the rubber hose with the new revised jig by analysis results is successfully conducted without any problem. Therefore the jig's design technology proposed in this paper may be useful for other items as well.

• Geomechanics and Engineering
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• v.34 no.2
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• pp.187-195
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• 2023

Intensive rainfall during the summer season in Korea has triggered numerous devastating landslides outside of downtown in mountainous areas. The 2D slope stability analysis that is generally used for cut slopes and embankments is inadequate to model slope failure in mountainous areas. This paper presents a new 3D slope stability formulation using the global sliding vector in the limit equilibrium method, and it uses an ellipsoidal slip surface for static and quasi-static analyses. The slip surface's flexibility of the ellipsoid shape gives a lower FS than the spherical failure shape in the Fellenius, Bishop, and Janbu's simplified methods. The increasing sub-columns of each column tend to increase the FS and converge to a steady value. The symmetrical geometric conditions of the convex turning corners do not indicate symmetrical failure of the surface in 3D analysis. Pseudo-static analysis shows that the horizontal seismic force decreases the FS and increases the mass volume at the critical failure state. The stability index takes the FS and corresponding sliding mass into consideration to assess the potential risk of slope failure in complex mountainous terrain. It is a valuable parameter for selecting a vulnerable area and evaluating the overall risk of slope failure.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3039-3044
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• 2007

A few fluid structure interaction analyses have been developed for turbomachinery blades in comparison with aircraft wings. Also, the existing aeroelastic analyses for turbomachinery blades have been mostly limited to cases with a steady freestream. In reality, however, the inflowing freestream is often pulsating. Therefore, this paper presents stability and forced response analyses of an isolated three-dimensional blade under pulsating freestream conditions. A new three-dimensional unsteady vortex lattice model under a pulsating freestream has been developed in discrete time domain to examine unsteady aerodynamic forces acting on a vibrating blade. The blade's structural behaviors have been analyzed by using a three-dimensional plate model. In the aeroelastic analysis, the flutter onset of a blade under pulsating freestream is predicted by the Floquet analysis. The new time domain method can predict aeroelastic stability as well as time history.

• Journal of Pharmacopuncture
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• v.18 no.1
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• pp.44-55
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• 2015

Objectives: Scolopendra subspinipes mutilans (S. subspinipes mutilans) is known as a traditional medicine and includes various amino acids, peptides and proteins. The amino acids in the pharmacopuncture extracted from S. subspinipes mutilans by using derivatization methods were analyzed quantitatively and qualitatively by using high performance liquid chromatography (HPLC) over a 12 month period to confirm its stability. Methods: Amino acids of pharmacopuncture extracted from S. subspinipes mutilans were derived by using O-phthaldialdehyde (OPA) & 9-fluorenyl methoxy carbonyl chloride (FMOC) reagent and were analyzed using HPLC. The amino acids were detected by using a diode array detector (DAD) and a fluorescence detector (FLD) to compare a mixed amino acid standard (STD) to the pharmacopuncture from centipedes. The stability tests on the pharmacopuncture from centipedes were done using HPLC for three conditions: a room temperature test chamber, an acceleration test chamber, and a cold test chamber. Results: The pharmacopuncture from centipedes was prepared by using the method of the Korean Pharmacopuncture Institute (KPI) and through quantitative analyses was shown to contain 9 amino acids of the 16 amino acids in the mixed amino acid STD. The amounts of the amino acids in the pharmacopuncture from centipedes were 34.37 ppm of aspartate, 123.72 ppm of arginine, 170.63 ppm of alanine, 59.55 ppm of leucine and 57 ppm of lysine. The relative standard deviation (RSD %) results for the pharmacopuncture from centipedes had a maximum value of 14.95% and minimum value of 1.795% on the room temperature test chamber, the acceleration test chamber and the cold test chamber stability tests. Conclusion: Stability tests on and quantitative and qualitative analyses of the amino acids in the pharmacopuncture extracted from centipedes by using derivatization methods were performed by using HPLC. Through research, we hope to determine the relationship between time and the concentrations of the amino acids in the pharmacopuncture extracted from centipedes.