• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.101-106
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• 2007

In this paper, the authors demonstrate a new idea to take the place of the real pressure vessel test, which should be carried out in a high pressure experiment unit before the real sea trial test. The idea is to make a pressure vessel model as a replica of the real pressure vessel test, which can reduce the cost of making a pressure vessel and large pressure experiment unit. The pressure vessel model was designedbased on linear-elastic, buckling equations and Finite Element Analysis. The manufactured pressure vessel model was investigated and monitored while the pressure test was being conducted. After the test, the result and the validity of the pressure vessel model as a replica of the real pressure vessel test was studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.743-749
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• 2005

In this work, two dynamic absorbers are introduced and designed to reduce the vibration of the large-size pressure vessel of a reactor for a petrochemical plant. The vibration modes and harmonic responses of the vessel are firstly analyzed by the finite element method. On the basis of the analyzed results, two dynamic absorbers are designed by a simple design theory. Furthermore, an optimization process is executed and an optimal design of the dynamic absorber is obtained to improve performance and structural safety of the vessel. As a result, the maximum displacement and stress of the vessel is decreased about 85% and 65% respectively, the design criteria being satisfied.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.5 s.98
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• pp.612-619
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• 2005

In this work. two dynamic absorbers are introduced and designed to reduce the vibration of the large-size pressure vessel of a reactor for a petrochemical plant. The vibration modes and harmonic responses of the vessel are firstly analyzed by the finite element method. On the basis of the analyzed results, two dynamic absorbers are designed by a simple design theory. Furthermore, an optimization process is executed and an optimal design of the dynamic absorber is obtained to improve performance and structural safety of the vessel. As a result, the maximum displacement and stress of the vessel is decreased about $85\%$ and $65\%$ respectively, the design criteria being satisfied.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.279-284
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• 2007

As a container vessel becomes larger, the bow flare becomes larger. The large bow flare structures are often subjected to dynamic pressure loads due to bow flare slamming occurring in rough seas. The aim of this paper is to investigate the characteristics of bow flare slamming pressure measured in a real voyage through the North Pacific Ocean. The characteristics of impact pressure load caused by slamming is addressed in terms of the pressure pulse-time history which involves rising time, peak pressure, decaying time and type of pressure decay. The values were presented using non-dimensional parameters.

• Transactions of Materials Processing
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• v.14 no.7 s.79
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• pp.613-618
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• 2005

The paper is concerned with the process design and the die design for manufacturing the preform of a large pressure vessel. The cold-working processes are introduced to improve the fatigue strength and to simplify the manufacturing process. By the finite element simulation, the parameter design is carried out, which is subjected to constraints such as the blank sire, press capacity and other minor limitations. The proposed design results are verified by the model experiments, in which the model is scaled down to one tenth of the original size.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.05a
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• pp.141-153
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• 1995

An incremental Total Lagrangian Formulation is implemented for the finite element analysis of laminated composite pressure vessel with consideration of the material and geometric nonlinearities. For large displacements/large rotations due to geometric nonlinearities, the incremental equations are derived using a quadratic approximation for the increment of the reference vectors in terms of the nodal rotation increments. This approach leads to a complete tangent stiffness matrix. For material nonlinearity, the analysis is performed by using the piecewise linear method, taking account of the nonlinear shear stress-strain relation. The results of numerical tests include the large deflection behavior of the selected composite shell problem. When compared with the previous analysis, tile results are in good agreement with them. As a practical example, filament wound pressure vessel is analyzed with consideration of the geometrically and materially nonlinearity. The numerical results agree fairly well with the existing experimental results.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.234-238
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• 2015

When we use a Finite Elements Method (FEM) to solve a linear static analysis problem, number of elements need to be sufficiently small for convergence of the solution. If we analysis a part, whose curvature is varying heavily, we face to determine how small the elements size is, because the calculated stress is increased as the elements are smaller. In this case, we need to analysis with mesh insensitive method, stress linearization. We can get a solution that is not varying with the elements size if the size is smaller than a certain level. In this paper, we evaluate a pressure vessel having geometrical discontinuities using stress linearization. First, we analysis the vessel with global model, including all part of the vessel, using large shell elements. Second, we analysis the local part of the vessel, which is the small part occurring maximum stress, using small continuum elements. Last, we evaluate the safety of the pressure vessel according to the ASME Sec. VIII Div 2.

• Computational Structural Engineering
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• v.10 no.4
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• pp.155-164
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• 1997

A reactor pressure vessel, which contains fuel assemblies and reactor vessel internals, has the thermal stress resulting from the cool-down and heat-up of the vessel wall in combination with the pressure stress from system pressure resulting in large stresses. The combination of the pressure stress and thermal stress along with a decrease in fracture toughness may cause through-wall propagation of a relatively small crack. Therefore, it is necessary to define the relations between operating pressure and temperature during cool-down and heat-up. In this study, theory of fracture mechanics for a pressure/temperature limit curve is investigated and a numerical procedure for generating it is developed. Plant-specific limit curves for the Kori unit 1 plant, the oldest nuclear power plant in Korea, have been obtained for several cooling and heating rates and their results are discussed.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2859-2874
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• 2024

This paper presents the finite element deformation and failure simulation of a typical Korean high-power reactor vessel under a severe accident characterized by large break loss of coolant (LBLOCA) with in-vessel retention of molten corium through external reactor vessel cooling (IVR-ERVC) conditions. Temperature distributions calculated using Modular Accident Analysis Program Version 5 (MAAP5) as thermal boundary conditions were used, and ABAQUS thermal and structural analyses were performed. After full ablation, the temperature of the inner surface in the thinnest section remained high (920 ℃), but the stress remained relatively low (less than 6 MPa). At the outer surface, the stress was as high as 250 MPa; however, the resulting plastic strain was small owing to the low temperature of 200 ℃. Variations in stress, inelastic strain, and temperature with time in the thinnest section suggest that the plastic and creep strains are saturated owing to stress relaxation, resulting in low cumulative damage. Thus, the lower head of the vessel can maintain its structural integrity under LBLOCA with IVR-ERVC conditions. The sensitivity analysis of internal pressure indicates the occurrence of failure in the thinnest section at an internal pressure >9.6 MPa via local necking followed by failure due to high stresses.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2634-2645
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• 1993

Dome structures of pressure vessels subjected to internal pressure are usually analyzed by linear elastic theory assuming small deformation. Geometric and material nonlinear behaviors appear in actual dome structures because of large deformation and loads exceeding yield strength. In this paper, linear and nonlinear analyses were performed for various hemispherical and torispherical domes to check the effects of geometric and material nonliearity on the stress and displacement by the finite element method. The effect of the geometric nonlinearity decreased the stress levels a lot for very thin general torispherical domes, which enables more realistic and effective design. The material nonlinear effects are negligible for hemispherical and optimum torispherical domes, and those are large for most of the general torispherical domes.