• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1583-1589
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• 2004

In this paper, A new finite element method for the time domain analysis of the dynamic stress intensity factor of two-dimensional viscoelastic body with a stationary central crack under the transient dynamic load is presented, which is based on the intergrodifferential equations of motion in the isotropic linear viscoelasticity and the Galerkin's method. The vlscoelastic material is assumed to be elastic in dilatation and behaves like a standard linear solid in shear. As a numerical example, the Chen's problem in viscoelastodynamic version is solved for the parametric study about the effect of viscosity and relaxation time on the dynamic stress intensity factor.

• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.1
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• pp.51-61
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• 2003

In the normal equations approach in which the ordering and factorization phases are separated, the factorization in the augmented system approach is computed dynamically. This means that in the augmented system the numerical factorization should be performed to obtain the non-zero structure of Cholesky factor L. This causes much time to set up the non-zero structure of Cholesky factor L. So, we present a method which can separate the ordering and numerical factorization in the augmented system. Experimental results show that the proposed method reduces the time for obtaining the non-zero structure of Cholesky factor L.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.05a
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• pp.325-329
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• 2003

This paper discuss the method of the system's efficient control using a Intelligent hybrid algorithm in nonlinear dynamics systems. Existing neural network and genetic algorithm for the control of non-linear systems work well in static states. but it be not particularly good in changeable states and must re-learn for the control of the system in the changed state. This time spend a lot of time. For the solution of this problem we suggest the intelligent hybrid self-tuning controller. it includes neural network, genetic algorithm and immune system. it is based on neural network, and immune system and genetic algorithm are added against a changed factor. We will call a change factor an antigen. When an antigen broke out, immune system come into action and genetic algorithm search an antibody. So the system is controled more stably and rapidly. Moreover, The Genetic algorithm use the memory address of the immune bank as a genetic factor. So it brings an advantage which the realization of a hardware easy.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.1-6
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• 2019

Foreground/background segmentation in video sequences is often one of the first tasks in machine vision applications, making it a critical part of the system. In this paper, we present an improved sample-based technique that provides robust background image as well as segmentation mask. The conventional multiple interval sampling (MIS) algorithm have suffer from the unbalance of computation time per frame and the rapid change of confidence factor of background pixel. To balance the computation amount, a random-based pixel update scheme is proposed and a spatial and temporal smoothing technique is adopted to increase reliability of the confidence factor. The proposed method allows the sampling queue to have more dispersed data in time and space, and provides more continuous and reliable confidence factor. Experimental results revealed that our method works well to estimate stable background image and the foreground mask.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.383-386
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• 2007

Recently, The percentile of the apartment housing within the apartment construction of domestic is increasing daily. Especially the construction duration in apartment construction is an very important factor which affects project cost. Therefore the construction companies the effort to shorten construction duration. The influence factors of the construction duration are analyzed to shorten construction duration through this tendency. The shown factors are needed to assessment method efficiently. This study is to suggest a method for the assessment of influence factors about the shortening of the construction time in apartment housing based on the FMEA(Failure Mode and Effect Analysis) method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.942-945
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• 2005

The purpose of this study is to suggest a fundamental data for change of dynamic properties according to the loading time of resilient materials. 18 kinds of resilient materials included 4 representative types were measured at the load time of 24hours and 2hours by the method of Korea standard (KS F 2868) measuring the dynamic stiffness and the loss factor of materials under floating floors. As a result, the dynamic stiffness was increased rapidly in case of expandable polystyrene and rubber materials according to the load time, especially before 2 hours. The loss factor was represented that rubber materials with high elasticity are high, and expandable polystyrene, polyester, poly ethylene materials with low elasticity are low.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.518-521
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• 1989

Recently, PWM cycloconverters that are frequency conversion system have been studied for eliminating do links of conventional converter and inverter systems. A new real-time method for generating PWM patterns is proposed in this paper. This method realizes sinusoidal input and output currents, controllable input displacement factor regardless of load power factor, and maximum output voltage range. Finally, feasibility of the proposed method is confirmed by simulation and experiments.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.157-164
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• 2004

Air voids in hardened concrete have an important influence on concrete durability such as resistance of freezing and thawing, permeability and surface scaling resistance. Linear traverse method and point count method in ASTM standard method have been widely used to estimate the air void system in hardened concrete. However, these methods are not used at present time, because they are is exhausted much time and effort. In previous study, air voids system of concrete was estimated by spacing factor. The purpose of this study organizes image analysis method by analyzing air contents, air voids distributions by diameters, air voids system as well as spacing factors after hardened concrete. The experimental variables institute of depth of specimen(top, middle, bottom), air contents(AE contents 0, 0.01, 0.03%).

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.11
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• pp.421-429
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• 1985

With the rapid increase of contingency cases due to complication of power system, the reduction of computation time in contingency analysis has become more significant than ever before. This paper deals with the development of a fast contingency analysis algorithm by using a matrix decomposition method. The proposed matrix decomposition method of contingency analysis yields an accurate solution by using the original triangular factor table. An outstanding feature of this method is of no need of factor table modification for network changes due to contingency outages. The proposed method is also applicable to multiple contingency analysis withremarkable reduction of computation time. The algorithm has been tested for a number of single and multiple contigencies in 17-bus and 50-bus systems. The numerical results show its applicability to practical power systems.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.2
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• pp.63-76
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• 2009

A study on the interference effects of overlapping tandem rotors in forward flight is conducted using the time-marching free-wake panel method which adopts field velocity boundary integral formulation. The conventional boundary integral formulation is numerically unstable for the cases when the blade and the wake are in close proximity to each other. In order to avoid this problem, this study applies the field velocity method and modifies the boundary integration formulation. The improved method is used for the parametric study on the advance ratio and the distance between the rotors. These are the parameters that most affect the interference of the tandem rotor in forward flight. Comparison of the aerodynamic performance shows that the horizontal distance between the rotors negligibly influences the overlap-induced power factor for high advance ratio. In addition, it shows that the overlap-induced power factor is inversely proportional to the squared vertical distance between the rotors, and that the overlap-induced power factor increases to a certain extent and decrease back as the advance ratio increases.