• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.71-80
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• 2001

The quantitative analysis of bearing capacity with stone column-mat is not ease because the bearing capacity of stone column is affected by so many parameters. The bearing capacity of stone column is mainly governed by horizontal resistance along the interface with soil. Also, this foundation system is affected by geometric factors such as column spacing, embedment ratio and failure surface inclination. Therefore, in this study, critical length and the effect of failure surface inclination was studied with single and group end bearing stone columns by loading tests. Results of model tests are compared to the present theoretical methods and are examined with FEM analysis.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.162-169
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• 2005

The functional external fixator system fur bone deformity near joints in legs using the worm gear was developed for curing the difference angles in fracture bone and the lengthening bar for curing the difference length in fracture bone. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for the bone deformity. The FE model using the compressive and bending FE analysis was applied to the FE analysis due to the angle differences. The results show that the compressive stiffness value in experiment was 175.43N/mm; the bending stiffness value in experiment was 259.74N/mm; compressive stiffness value in FEM was 188.67N/mm; bending stiffness value in FEA was 285.71N/mm. The errors between experiments and FEA were less than 10%. The maximum stress (157MPa) to the angle of clamp was lower than the yield stress (176.4MPa) of SUS316L. The stiffnesses in both axial compressive and bending of the new fixator are about 2 times higher than other products except EBI (2003).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1248-1251
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• 2004

The functional external fixator system for bone deformity near joints in legs using the worm gear was developed for curing the difference angles in fracture bone and the lengthening bar for curing the difference length in fracture bone. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for bone deformity near joints in legs. The FE model using the compressive and bending FE analysis was applied the FE analysis due to the angle differences. The results show that the compressive stiffness value in experiment was 175.43N/mm, the bending stiffness value in experiment was 259.74N/mm, compressive stiffness value in FEM was 188.67N/mm, bending stiffness value in FEA was 285.71N/mm. The errors between experiments and FEA were less than 10％. The maximum stress (157MPa) to the angle of clamp was lower than the yield stress (176.4MPa) of SUS316L. The stiffnesses in both axial compressive and bending of the new fixator are about 2 times higher than other products except EBI (2003).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.136-140
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• 2006

We are developing a vol-oxidizer which transforms the spent $UO_2$ pellets into the $U_3O_8$ power through oxidizing process. The vol-oxidizer consists of furnace, filter, heater and valve etc. When the filter is blocked by the powder, the internal pressure of the furnace is increased owing to the air flow restriction. Then, the furnace vessel is swelled and deformed by it. In this paper, we proposed a procedure of the thermal analysis for furnace vessel design of spent fuel vol-oxidizer. In this work, we determined the thickness of the furnace through analyzing the internal pressure and the thermal stress of the furnace with respect to various pressure and temperature. To analyze the thermal stress, we used ANSYS 8.0 for constructing a FEM model of the furnace, and then analyzed it based on the ASME code. We also surveyed the material property and yield stress of SUS304 with various temperature. Analysis results are compared with the yield stress of the material. We manufactured the furnace and conduct the verification experiments.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.21-29
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• 2006

Light weight filling method prevents settlement of ground by decreasing the weight of fills. This method is increasingly used for it's convenience and workability. Styrofoam is increasingly used as a lightweight filling material in soft ground. The beneficial effects of the use of EPS derive from minimizing the stress increment, increasing the bearing capacity and reducing the settlement. For this study, model test and FEM analysis of bearing capacity is carried out composing two-layered ground with clay in the lower layer and lightweight filling material in upper layer. Based on the results obtained here in this study, it is concluded that the use of recycled EPS beads is acceptable lightweight fill. Light weight fills used for disposal is superior to typical embankment fills in bearing capacity.

• Journal of the Korean Institute of Gas
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• v.9 no.1 s.26
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• pp.26-32
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• 2005

This paper presents the design safety of metal seals in pressure vessels. For a high-pressure vessel, a metal seal is usually used as a primary sealing, and an elastomeric rubber O-ring is adopted as a secondary sealing unit. The FEM computed results show that an aluminium material for sealing a gas leakage is superior to a steel one because of the thermal expansion rate. The deformation and stress distributions on the metal seal and pressure vessel structures are mainly dominated by transferred temperature compared to those of the gas pressure in which is supplied by an external pump. Thus, the temperature of a metal seal material should be restricted to under $200^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.10 no.1 s.30
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• pp.56-60
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• 2006

The connection part (corbel) between bottom slab and side wall in inground LNG storage tank has hinge conditions partly fixed by using anchor bars to reduce stress concentration. The corbel deforms in both radial and vertical directions under load conditions of the LNG tank such as LNG temperature, hydraulic pressure, etc. Membrane is an important part from the viewpoint of design because the deformation of the corbel is transformed directly to the membrane and superposed with other deformations. Behavior of the corbel has been investigated through various sensors to measure temperature, load and displacement. And the test data have been compared with finite element results analysis to propose a more reasonable design of LNG storage tank.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.537-544
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• 2003

This paper deals with stress corrosion cracking behavior of high strength steel exposed to marine environments. The objective is to determine the time to failure as a function of hydrogen concentration and tensile stress in the wires. A crack growth curve is modeled using finite element method (FEM) program. The coupled hydrogen diffusion-stress analyses of SCC were programmed separately. The first part is calculating stress and stress intensity /sup 1)/factor of a cylindrical shell, prestressing tendon or suspension bridge wires, from the initiation of cracks to rupture. Virtual crack extension method, contour integral method, and crack tip elements are used for the calculation of stresses in front of the crack tip. Comparisons of the result show a good agreement with the analytical equations and wire tests. The second part of the study deals with the programming of hydrogen diffusion, affected by hydrostatic stress, calculated at the location of boundary of plastic area around the crack tip. The results of paper can be used in the design and management of prestressed structures, cable stayed and suspension bridges. Time dependent correlated parallel reliabilities of a cable, composed of 36 wires, were evaluated by the consideration of the deterioration of stress corrosion cracking.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.7-12
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• 2000

The automatic turbine startup system provides turbine control based on thermal stress. During the startup, control system monitors and evaluates main components of turbine using damage mechanism and life assessment. In case of valve chest, the temperature of inner/outer wall is measured by thermo-couples and the safety of these values are evaluated by using allowable ${\Delta}T$ limit curve during the startup. Because allowable ${\Delta}T$ limit curve includes life assessment, it is possible to apply this curve to turbine control system. In this paper, low cycle fatigue damage and combined rupture and low cycle fatigue damage criterion proposed for yielding the allowable ${\Delta}T$ limit curve of CV(control valve) chest. To calculate low cycle fatigue damage, the stress analysis of valve chest has peformed using FEM. Automatic turbine startup to assure service life of CV was achieved using allowable ${\Delta}T$ limit curve.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.1-6
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• 2002

The automatic turbine startup system provides turbine control based on thermal stress. During the startup, control system monitors and evaluates main components of turbine using damage mechanism and life assessment. In case of valve chest, the temperature of inner/outer wall is measured by thermo-couples and the safety of these values are evaluated by using allowable △T limit currie during the startup. Because allowable ΔT limit curve includes life assessment, it is possible to apply this curve to turbine control system. In this paper, low cycle fatigue damage, combined rupture and low cycle fatigue damage criterion were proposed for yielding the allowable ΔTf limit curve of CV(control valve) chest. To calculate low cycle fatigue damage, the stress analysis of valve chest has been performed using FEM. Automatic turbine startup to assure service life of CV was achieved using allowable ΔT limit curve.