• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.2
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• pp.78-86
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• 1990

The vertical attenuation of structureborne noise in a ship structure is studied by means of the wave guide theory. When modeling a ship structure as an acoustic wave guide system the cross mode is derived from the assumption about the boundary of the system, i.e. the constraint due to transverse frames. In this paper, the constraint is relaxed so that the displacement at the boundaries could take place. The numerical result shows better agreement with the measured one than that of the previous assumption of fixed boundary condition in the low frequency region. The effect of local changes of mass and damping factors on the attenuation losses are also investigated numerically.

• Nuclear Engineering and Technology
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• v.21 no.3
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• pp.193-204
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• 1989

This paper develops a new method for reconstructing neutron flux distribution, that is based on the maximum entropy Principle in information theory. The Probability distribution that maximizes the entropy Provides the most unbiased objective Probability distribution within the known partial information. The partial information are the assembly volume-averaged neutron flux, the surface-averaged neutron fluxes and the surface-averaged neutron currents, that are the results of the nodal calculation. The flux distribution on the boundary of a fuel assembly, which is the boundary condition for the neutron diffusion equation, is transformed into the probability distribution in the entropy expression. The most objective boundary flux distribution is deduced using the results of the nodal calculation by the maximum entropy method. This boundary flux distribution is then used as the boundary condition in a procedure of the imbedded heterogeneous assembly calculation to provide detailed flux distribution. The results of the new method applied to several PWR benchmark problem assemblies show that the reconstruction errors are comparable with those of the form function methods in inner region of the assembly while they are relatively large near the boundary of the assembly. The incorporation of the surface-averaged neutron currents in the constraint information (that is not done in the present study) should provide better results.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1146-1154
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• 2008

This paper presents a method for the acceleration analysis of multi-legged walking robots in consideration of the frictional ground contact. This method is based on both unified dynamic equation for finding the acceleration of a robot's body and constraint equation for satisfying no-slip condition. After the dynamic equation representing relationship between actuator torques and body acceleration, is derived from the force and acceleration relationship between foot and body's gravity center, the constraint equation is formulated to reconfigure the maximum torque boundaries satisfying no-slip condition from given original actuator torque boundaries. From application of the reconfigured torques to the dynamic equation, interested acceleration boundaries are obtained. The approach based on above two equations, is adapted to the changes of degree-of-freedoms of legs as well as friction of ground. And the method provides the maximum translational and rotational acceleration boundaries of body's center that are achievable in every direction without occurring slipping at the contact points or saturating all actuators. Given the torque limits in infinite normsense, the resultant accelerations are derived as a polytope. From the proposed method, we obtained achievable acceleration boundaries of 4-legged and 6-legged walking robot system successfully.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.4
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• pp.285-289
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• 2002

This study is object to flow analysis of ice cone die. The finite element model was developed to compute the flow, velocity and pressure for ice cone die. For flow analysis using result from FEM Code. This flow analysis results, many variables such as internal pressure, boundary condition, constraint condition and velocity condition are considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.418-421
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• 2003

This study is object to design and souctural analysis of duck breeding system. Design tool is Auto CAD and souctural analysis of duck breeding system using result from ANSYS Code. The finite element model was developed to compute the stress, strain and displacement for duck breeding system. This structural analysis results, many variables such as boundary condition, constraint condition and load condition are considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.326-330
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• 2004

This study is object to design and structural analysis of Leg Extension Machine. Design tool is AutoCAD and structural analysis of Leg Extension Machine using result from ANSYS Code. This structural analysis results, many variables such as boundary condition, constraint condition and load condition are considered.

• International Journal of Automotive Technology
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• v.1 no.2
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• pp.79-87
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• 2000

Analytical approach was followed in this work under both the steady state and transient operating conditions to find optimum boundary conditions, where the optically accessible quartz engine can run safely without breaking. Temperature and stress distribution was predicted by FEM analysis. In order to validate thermal boundary condition, model reliability and constraint, outside cylinder temperature was measured and previous study was also followed up numerically. To reduce thermal stress level, three types of outside cooling (natural, moderate forced and intensive forced convection) were considered. Effects of clamping force and combustion pressure were conducted to investigate mechanical stress level. Cylinder thickness, was changed to fine the optimum cylinder thickness. The versatile results achieved from this work can be basic indication, which is capable of causing a sudden quartz cylinder breaking during fired operation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.411-418
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• 2004

Using a level set method we develop a shape optimization method applied to energy flow problems in steady state. The boundaries are implicitly represented by the level set function obtainable from the 'Hamilton-Jacobi type' equation with the 'Up-wind scheme.' The developed method defines a Lagrangian function for the constrained optimization. It minimizes a generalized compliance, satisfying the constraint of allowable volume through the variations of implicit boundary. During the optimization, the boundary velocity to integrate the Hamilton-Jacobi equation is obtained from the optimality condition for the Lagrangian function. Compared with the established topology optimization method, the developed one has no numerical instability such as checkerboard problems and easy representation of topological shape variations.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.191-204
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• 2006

This paper investigate the optimum thickness distribution of plate structure with different essential boundary conditions in the fundamental natural frequency maximization problem. In this study, the fundamental natural frequency is considered as the objective function to be maximized and the initial volume of structures is used as the constraint function. The computer-aided geometric design (CAGD) such as Coon's patch representation is used to represent the thickness distribution of plates. A reliable degenerated shell finite element is adopted calculate the accurate fundamental natural frequency of the plates. Robust optimization algorithms implemented in the optimizer DoT are adopted to search optimum thickness values during the optimization iteration. Finally, the optimum thickness distribution with respect to different boundary condition

• Architectural research
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• v.3 no.1
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• pp.37-44
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• 2001

This study aims to find out sector effects with the appraisal of building energy systems of urban ecosystem considering cost effects and environmental constraints condition such as climatic change factors including $CO_2$ gas which are not dealt in the institutional boundary as components standards and performance standards on energy performance of each part of a building applied on heavy energy spending buildings at present. The results of the appraisal of building energy systems shows that the existing building energy systems are not enough to fulfil the environmental condition under the environmental constraints supposing QELROs(Quantified Emission Limitation and Reduction Objectives) of carbon-dioxide exhaust. Henceforth, it is needed to fulfill the environmental criteria required by the Climatic Change Agreement for improving the adiabatic performance of each part of a building and active using of the solar energy.