• Interaction and multiscale mechanics
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• v.6 no.4
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• pp.357-375
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• 2013

In this paper, the forced vibration problem of an Euler-Bernoulli beam that is joined with a semi-infinite field of a compressible fluid is considered as a boundary value problem (BVP). This BVP includes two partial differential equations (PDE) and some boundary conditions (BC), which are introduced comprehensively. After that, the closed-form solution of this fluid-structure interaction problem is obtained in the frequency domain. Some mathematical techniques are utilized, and two unknown functions of the BVP, including the beam displacement at each section and the fluid dynamic pressure at all points, are attained. These functions are expressed as an infinite series and evaluated quantitatively for a real example in the results section. In addition, finite element analysis is carried out for comparison.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.525-529
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• 2004

A novel translational 3-dof parallel mechanism is proposed and analyzed. The mechanism consists of three RRPS serial subchains and an additional passive 3-dof type serial subchain. Three RRPS serial subchains alone may form a structure of the 6-DOF Stewart Platform mechanism. However, in the proposed mechanism, an additional passive serial subchain acts as constraints to restrict the output motion of the mechanism in 3-DOF translational space. The closed form position solutions of the proposed mechanism and its first-order kinematic model are derived. Then its workspace size and kinematic characteristics are examined via kinematic isotropic index.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.520-524
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• 2004

In this work, a novel spherical 3-dof parallel mechanism is proposed and analyzed. The mechanism consists of three RRPS serial subchains and an additional passive 3-dof type serial subchain. Three RRPS serial subchains alone may form a structure of 6-DOF Stewart Platform mechanism. However, in the proposed mechanism, an additional passive serial subchain acts as constraints to restrict the output motion of the mechanism within 3-DOF spherical space. The closed form solutions of position analysis of the proposed mechanism and its first-order kinematic model are derived. Then its workspace size and kinematic characteristics are examined via kinematic isotropic index.

• Bulletin of the Korean Mathematical Society
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• v.49 no.2
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• pp.435-443
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• 2012

The Yamabe invariant is a topological invariant of a smooth closed manifold, which contains information about possible scalar curvature on it. It is well-known that a product manifold $T^m{\times}B$ where $T^m$ is the m-dimensional torus, and B is a closed spin manifold with nonzero $\^{A}$-genus has zero Yamabe invariant. We generalize this to various T-structured manifolds, for example $T^m$-bundles over such B whose transition functions take values in Sp(m, $\mathbb{Z}$) (or Sp(m - 1, $\mathbb{Z}$) ${\oplus}\;{{\pm}1}$ for odd m).

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.546-549
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• 1990

This study introduces the three-dimensional information about moving objects. Relative motion between textured objects and observer generates a time varying optic array at the image, from which image motion of contours can be extracted. Closed-form solutions are proposed for the structure and motion of planar and curved surface patches. The analytic solution for curved surface patches combines the transformation of Longuet-Higgins with the planar surface solution of Subbarao and Waxman. Ovoid patches are shown to construct a unique transform angle. Thus, ovoid patches almost always yield a unique 3D interpretation.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.98-109
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• 2000

A new PC-based Engine Control system (ECS) is developed using an object oriented programming method. This system provides more convenient environment for engine tests, easier user interface and extended functions. A Windows-based ECS software is developed with class, and the class structure is built on encapsulation and abstraction. The closed-loop engine control scheme can be easily constructed by using dynamic link library and multitasking. This means that a user can perform desired experiments without clear knowledge of the hardware structure of the ECS. Also this system allows a user to individually control the ignition and fuel injection for each cylinder in a simple manner such as through a keyboard/mouse or in a real-time operation from a closed-loop control program.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.459-466
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• 2002

The purpose of this study is to propose a new method for evaluating equivalent damping ratios of a structure with supplemental damping devices to assess their control effect quantitatively. A MDOF system is transformed to an equivalent SDOF system based on the assumption that the first mode dominates structural response. Approximate closed-form formulas for the evaluation of the first damping ratio are presented for various damping devices. Through numerical analysis of a ten-story building equipped with damping devices, the effectiveness of equivalent SDOF model and closed form formulas are verified.

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.63-66
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• 2001

In order to derive simple and accurate closed-form spatial Greep’s functions for the thick microstrip substrate, an efficient method based on the two-level approach, which circumvents the burdensome steps (i.e., without necessity of extraction of quasi-static contributions and subsequent determination of approximation parameters) in the previous complex image method, is considered in conjunction with the use of the original Prony`s method. The present method is observed to give more accurate results for the evaluation of the Green`s functions over wider frequency range independently of the source-to-field distances than the previous method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.938-943
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• 2004

In this paper, we propose a T-shaped DGS for CPW and provide the closed-form solutions for power loss rate, and bandwidth of the DGS. The proposed T-shaped DGS structure has a range of capacitance(C) 5.5 times wider than the dumbbell-shaped DGS structure. In addition we also analyze relations between R, L, C values of the DGS equivalent circuit and total loss rate, BW, $\omega_0$ of the DGS.

• Coupled systems mechanics
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• v.3 no.4
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• pp.385-403
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• 2014

In this paper, the forced vibration problem of an Euler-Bernoulli beam that is joined with a semi-infinite field of a compressible fluid is considered as a boundary value problem (BVP). This BVP includes two partial differential equations (PDE) and some boundary conditions (BC), which are introduced comprehensively. After that, the closed-form solution of this fluid-structure interaction problem is obtained in the frequency domain. Some mathematical techniques are utilized, and two unknown functions of the BVP, including the beam displacement at each section and the fluid dynamic pressure at all points, are attained. These functions are expressed as an infinite series and evaluated quantitatively for a real example in the results section. In addition, finite element analysis is carried out for comparison.