• Proceedings of the KSME Conference
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• 2000.11a
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• pp.486-491
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• 2000

In this study, finite elements addition and removal method by stress range is applied to optimize shapes in structures, without using classical and numerical optimization methods and search methods. The program based on this algorithm is developed and compared to theoritial results with considerable accuracy. Classical methods need mesh generation for finite element analysis for every iteration, the developed method needs updated mesh data such as coordinates of nodes, elements connectivity, and loads on nodes. And other tools of finite element analysis can be in use as a black box to interface with this program.

• Journal of Communications and Networks
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• v.14 no.3
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• pp.273-279
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• 2012

In this paper, we propose an iterative interstream interference cancellation technique for system with frequency selective multiple-input multiple-output (MIMO) channel. Our method is inspired by the fact that the cancellation of the interstream interference can be regarded as a reduction in the magnitude of the interfering channel. We show that, as iteration goes on, the channel experienced by the equalizer gets close to the single input multiple output (SIMO) channel and, therefore, the proposed SIMO-like equalizer achieves improved equalization performance in terms of normalized mean square error. From simulations on downlink communications of $2{\times}2$ MIMO systems in high speed packet access universal mobile telecommunications system standard, we show that the proposed method provides substantial performance gain over the conventional receiver algorithms.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.148-159
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• 1999

A numerical method is presented for the dynamic analysis of spur gears rotating with very high angular speeds. For an efficient computation each gear is assumed to consist of a rotating rigid disk and an elastic tooth having mass, and finite element formulations are used for the equations of motion of the tooth. The geometric constraint is imposed between the rigid disk and the elastic tooth to fix them, and contact condition is imposed between the meshing teeth of the gears. At each iteration of each time step the Lagrange multiplier and contact force are revised by using the constraint error vector, and then the whole equations of motion are time integrated with the given Lagrange multiplier and contact force. For the accurate solution the velocity and acceleration constraints as well as the displacement constraint are satisfied by the monotone reductions of the constraint error vectors. Computing procedures associated with the iterative schemes are explained and numerical simulations are conducted with the spur gears.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.470-478
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• 2006

An efficient method for change of eigenvectors and eigenvalues due to the modifying proportional damping structure using sensitivity coefficients is presented. Sensitivity coefficients are determined by iteration with eigenvalue and eigenvectors before modification of system. The proposed method is applied to examples of 3 degrees of freedom system and plate by modifying mass and stiffness. The predicted change of eigenvectors and eigenvalues are in a good agreement with these from the structural re-analysis after modification of mass and stiffness.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.2
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• pp.63-68
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• 1998

This study is aimed to predict the configuration and tension of a towing cable of a side-scan sonar which plays an important role in developing ocean resources. The governing equations of 3-D static equilibrium equations for a flexible cable are derived and solved using a finite difference method. The forces considered in this paper are effective weights, drag forces due to currents and ship moving, and the tension at both ends of the towing cable. The governing equations are non-linear, so an iteration method is applied to solve the equation. A case study is carried out for several different conditions. The result will be useful for predicting the location of a side-scan sonar and to design the towing system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.1
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• pp.137-142
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• 1990

A theory for the synthesis of a SDF including the filter modulation is suggested. In the filter synthesis, the iteration equation was used to iterate trial solution vectors. A computer simulation of the fSDF method using threshold binary images of the flight objects over a range of aspect angles was performed for POF and BPOF. The constructed fSDF filters are capable of obtaining the specified peak correlation response within a 1.7%-4.0% error range, after several iterations. However, the conventional pSDF/POFs, BPOFs are not. The results indicate POFs and BPOs can be made to perform well for distortion invariant optical pattern recognition using the fSDF method.

• International Journal of Reliability and Applications
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• v.3 no.3
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• pp.133-145
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• 2002

The traditional methods of evaluating the performance of a network by enumerating all possible states may quickly become computationally prohibitive, since the number of states grows exponentially as the number of components increases. In such cases, enumerating only the most probable states would provide a good approximation. In this paper, we propose a method which efficiently generates upper and lower bounds for coherent performance measures utilizing the most probable states. Compared with Yang and Kubat's method, our procedure significantly reduces the complexity and memory requirement per iteration for computing the bounds and thereby, achieves the given degree of accuracy or the coverage within a shorter time.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.266-273
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• 1995

An efficient dynamic analysis method is developed f3r building structures subjected to ground home loadings. The soil medium is modeled using the finite elements and infinite elements. Then, the dynamic stiffness of the soil medium is calculated at the interfacial nodes between the soil and the building foundation. The equivalent subway loading at the interfacial nodes are obtained from the wave propagation analysis of the subway loading through the soil medium. The dynamic response of the building Is computed using the mode superposition method equipped with gauss-seidel iteration technique. The analysis is carried out by the frequency domain and the time domain methods.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.333-342
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• 1999

An improved optimization algorithm for multi-objective and multi-level (MO/ML) optimum design of steel frames is proposed in this paper. In order to optimize the steel frames under seismic load, two main objective functions need to be considered for minimizing the structural weight and maximizing the strain energy. For the efficiency of the proposed method, well known multi-level optimization techniques using decomposition method that separately utilizes both system-level and element-level optimizations and an artificial constraint deletion technique are incorporated in the algorithm. And also dynamic analysis is executed to evaluate the implicit function of structural strain energy at each iteration step. To save the numerical efforts, an efficient reanalysis technique through sensitivity analysis of dynamic properties is unposed in the paper. The efficiency and robustness of the improved MOML algorithm, compared with a plain MOML algorithm, is successfully demonstrated in the numerical examples.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.87-94
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• 1997

The circular plate resting on Boussinesq's half-space model under axisymmetric loading is studied by a finite element procedure to evaluate the distribution of contact pressure between plate and elastic half-space. The displacement of half-space due to axisymmetric surface loading can be evaluated by double integration of Boussinesq's solution. On that case the analytical integration can be executed for the radial direction but the analytical integration for the circumferential direction is impossible and the numerical integration should be considered. With the radial integration we can get non-dimensional function. Then the numerical integration for the formula is executed for the circumferential direction and the results are approximated 5th order Polynomials by using the least square method. With these 5th order approximate formula, the flexibility matrix of half-space is constructed as the coefficient matrix of nodal contact pressure by the finite element procedures. Iteration procedures are attempted by using this method to determine the separated region.