• Journal of the Korean Mathematical Society
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• v.48 no.6
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• pp.1101-1123
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• 2011

Numerical schemes are routinely used to predict the behavior of continuous dynamical systems. All such schemes transform flows into maps, which can possess dynamical behavior deviating from their continuous counterparts. Here the common bifurcations of scalar dynamical systems are transformed under a class of algorithms known as linearized one-point collocation methods. Through the use of normal forms, we prove that each such bifurcation in an originating flow gives rise to an exactly corresponding one in its discretization. The conditions for spurious period doubling behavior under this class of algorithm are derived. We discuss the global behavioral consequences of a singular set induced by the discretizing methods, including loss of monotonicity of solutions, intermittency, and distortion of attractor basins.

• Journal of applied mathematics & informatics
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• v.3 no.2
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• pp.193-204
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• 1996

Overflow queuing models are ofter analyzed by explicitly solving a large sparse singular linear systems arising from Kolmogorov balance equation. The system is often converted into an eigenvalue problem the dominant eigenvector of which is the desired null vector. In this paper we convert an overflow queuing problem the dominant eigenvector of which is the desired null vector. In this paper we convert an overflow queuing problem into an overflow queuing problem into an eigen-value problem into an eigen-value problem of size 1/2 of the original. Then we devise an orthogonal projector that enhances its convergence by removing unsanted eigen-components effectively. Numerical result with some suggestion is given at the end.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.762-769
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• 2002

This paper presents how effective it is to use many features for improving the speed and accuracy of visual servo systems. Some rank conditions which relate the image Jacobian to the control performance are derived. The focus is to describe that the accuracy of the camera position control in the world coordinate system is increased by utilizing redundant features in this paper. It is also proven that the accuracy is improved by increasing the number of features involved. Effectiveness of the redundant features is evaluated by the smallest singular value of the image Jacobian which is closely related to the accuracy with respect to the world coordinate system. Usefulness of the redundant features is verified by the real time experiments on a Dual-Arm robot manipulator made by Samsung Electronic Co. Ltd..

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.15-23
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• 2011

The purpose of this paper is to investigate the time behavior of a multiple crack problems. It is assumed that the medium contains cracks perpendicular to the crack surfaces, that the thermo-mechanical properties are continuous functions of the thickness coordinate. we use the laminated composite plate model to simulate the material non-homogeneity. By utilizing the Laplace transform and Fourier transform techniques, the multiple crack problems in the non-homogeneous medium is formulated. Singular integral equations are derived and solved to investigate the multiple crack problems. As a numerical illustration, transient thermal stress intensity factors(TSIFs) for a functionally graded material plate subjected to sudden heating on its boundary are provided. The variation in the TSIFs due to the change in material gradient and the crack position is studied.

• Korean Institute of Interior Design Journal
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• v.17 no.1
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• pp.162-169
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• 2008

Philippe Starck is a famous french designer known for his creative works in all aspects of life from architectural space to product design. Especially, in regard to furniture, he designed more than 250 works with various design characteristics. This study therefore aims to examinate the characteristics of furniture designed by Philippe Starck through assessment of his design background and philosophy, evaluation of fifty or so of his works in terms of their function, form, material, and emotions, and lastly through a chronological analysis. As a result from this study, following various results are drawn as design characteristic through forty six representative cases: 1) possibility of fabrication and transformation 2) multi-function or optional function for user 3) pursuit of simplicity using the characteristic of singular material or mono block and immateriality 4) emotional approach in design 5) non-design method such as use of archetype or historical form.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1944-1948
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• 2005

This paper presents how it is effective to use many features for improving the speed and the accuracy of the visual servo systems. Some rank conditions which relate the image Jacobian and the control performance are derived. It is also proven that the accuracy is improved by increasing the number of features. Effectiveness of the redundant features is evaluated by the smallest singular value of the image Jacobian which is closely related to the accuracy with respect to the world coordinate system. Usefulness of the redundant features is verified by the real time experiments on a Dual-Arm Robot manipulator made in Samsung Electronic Co. Ltd

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.517-523
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• 2010

In this paper, we proposed an algorithm to detect aggressive driving status by analysing six kinds of driving patterns, which was achieved by comparing for the feature vectors using mahalanobis distance. The first step is to construct feature matrix of $6{\times}2$ size using frequency response of the time-series accelerometer data. Singular value decomposition makes it possible to find the dominant eigenvalue and its corresponding eigenvector. We use the eigenvector as the feature vector of the driving pattern. We conducted real experiments using three drivers to see the effects of recognition. Although there exists differences from individual drivers, we showed that driving patterns can be recognized with about 80% accuracy. Further research topics will include the development of aggressive driving warning system by improving the proposed technique and combining with post-processing of accelerometer signals.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.54.3-55
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• 2016

We model the spectral energy distribution (SED) of the Class 0 protostar L1527 IRS using a dust continuum radiative transfer code RADMC-3D to study the initial condition of gravitational collapse. To constrain the envelope structure, we use the data obtained by Herschel /PACS, which covers the far-infrared regime ($55-190{\mu}m$) where the SED of L1527 IRS peaks. According to our modeling, a more flattened density profile fits the far-infrared SED of L1527 IRS better than the density profile of a rotating and infalling envelope. Thus, we employ the density structure of a Bonnor-Ebert sphere, which consists of the inner flat-topped and the outer power-law regions and is often used for describing the density structure of the youngest sources in the low mass star formation process. A Bonnor-Ebert sphere fits very well the observed SED at ${\lambda}$ > $10{\mu}m$, suggesting that L1527 IRS might collapse from an unstable Bonnor-Ebert sphere rather than a singular isothermal sphere.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.12
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• pp.427-434
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• 1983

Singular Value Decomposition of 2-D Finite Impulse Response was used to design a variable cutoff 2-D FIR filters. Basically this approach allows to use 1-D techniques while dealing with 2-D filters. In this paper, our aim is to provide away of easily tuning 2-D FIR filters. For example, one would like to adjust interactively the cutoff frequency of a 2-D Circular Symmetric low-pass filter on an image processing system. The decomposition of 2-D FIR filters along with techniques available for tuning 1-D FIR filters allows such adjustment. Several design examples are shown.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.497-501
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• 2009

When modal tests on the large structures and machinery are performed, it is in general difficult and inaccurate to use artificial excitation devices such as impact hammers, because of insufficient capacity of the device and different environmental conditions of the concerned structures. Therefore, the Operational Modal Analysis(OMA) technique, which is performed by measuring only vibration responses during the operation of the objective product, can be one alternative. In this paper, the way to identify natural frequencies, mode shapes and damping ratios of a ship by using the OMA during the sea trail is described.