• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.97-104
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• 2007

Vibration analysis of a rigid body supported by in-parallel linear springs can be greatly simplified by utilizing the conditions for a plane of symmetry. The vibration modes of an oscillatory system having plane of symmetry are classified into the in-plane and out-of-plane modes. From the viewpoint of screw theory, they represent respectively the vibration axes perpendicular to the plane of symmetry and lying in the plane of symmetry. In this paper, the sets of orthogonal and mutually intersecting three springs are used as resilient support of a rigid body. The geometrical conditions for the system to have a plane of symmetry and diagonalized stiffness matrix are presented. From the orthogonality of the vibration modes with respect to the inertia matrix, the geometrical relation between the reaction wrenches and the vibration modes are derived. This geometrical relation is then used to get the cubic design equation for the design of out-of-plane modes. The numerical design example of engine mounts is presented in order to explain the suggested design technique.

• Journal of KSNVE
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• v.9 no.5
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• pp.984-990
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• 1999

This paper presents the geometrical methodology to decouple the vibration modes of an elastically supported single rigid body in three-dimensional space. It is shown that the vibration modes can be decoupled by placing the center of elasticity at suitable locations and thereby yielding the plane(s) of symmetry for the given stiffness matrix. The developed methodology has been applied to the actuator supported by the 4-wire suspensions in optical discs, which has one plane of symmetry. For this numerical example, the axes of vibrations have been computed and illustrated with the natural frequencies. The forced response at the objective lens is represented and its geometrical interpretation has been explained as the mutual moment between the axis of vibration and the applied wrench times the line coordinates of the axis of vibration.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.285-286
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• 1996

A systematric method of exploring the 'geometrical' and 'non-geometrical' constants of the motion for an arbitrary spacetime is presented. This is done by introducing a series of coupled differential equation for the generators of the symmetry group of Vlasov's equation. The method is applied to the case of the maximaly symmetric spectime, and the geometrical and non-geometrical constants of motion are obtained.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1367-1370
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• 1997

This paper presents a vision algorithm for finding the centers of steam generator tubes using the generalized symmetry transform, which is used for ECT(Eddy Current Test) of steam generator tubes in nuclear power plants. The geometrical properties of the image representing steam generator tubes shows that they have amost circular or somewhat elliptic appearances and each tube has strong symmetry about its center. So we apply the generalized symmetry transform to finding centers of steam geneator tubes. But applying the generalized symmetry transform itself without any modification gives difficulties in obtaining the exact centers of steam generator tubes. But applying the generalized symmetry transform itself without any modification gives difficulties in obtaining the exact centers of tubes due to the shadow effect generated by the local light installed inside steam generator. Therefore we make the generalized symmetry transform modified, which uses a modified phase weight function in getting the symmetry magnitude in order to overcome the misleading effect by the local light. The experimental results indicate that the proposed vision algorithm efficiently recongnizes centers of steam generator tubes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.49-50
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• 2006

• Journal of The Korean Association For Science Education
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• v.15 no.1
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• pp.1-5
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• 1995

One of the problem of science education in terms of its status as a unique discipline is the tendency of qualitative, rather than quantitative, arguments and judgements on research activities. In this study, a model called "Diamond Model" and an index formula for the balance of researches are suggested for achieving more pictoricaI and quantitative understandings on the distribution of researches in science education. Diamond Model is consisted of two dimensions corresponding to two main long-debated issues in science education, i.e. the dimension of cognitive-affective and the dimension of concept-process. In Diamond Model the geometrical symmetry represents the the balance of researches. An index formula for the balance was developed in order to ensure that the value of the index is between 0 to 1 and the numerical values of the index corresponds to the geometrical symmetry of the diamond. Then, in order to check their utility, the model and the index formula were applied to analyze the research papers appeared in JKARSE for the last 10 years.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.7
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• pp.462-467
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• 2000

In general, when geometry and current distribution have a periodic or symmetric property, the analysis of a part model is sufficient to represent that of a whole model by using the periodic boundary condition. It is impossible, however, to apply the periodic boundary condition when the current distribution is not symmetric even if the geometry of the model is symmetric. In this paper, a novel technique to resolve this problem is proposed. Even when the geometry is symmetric and the current distribution is not, the proposed method enables that calculation time for a whole model is reduced to that for a part model. The proposed method is applied to a deflection yoke (DY), and validness and efficiency of the method are verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.110-117
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• 2000

Vibration modes obtained from a modal analysis can be better explained from a screw theoretical standpoint. A vibration mode can be geometrically interpreted as a pure rotation about the vibration center in a plane and as the twisting motion on a screw in a three dimensional space. This paper, presents the method to diagonalize a spatial stiffness matrix by use of a parallel axis congruence transformation. It also describes that the stiffness matrix diagonalized by a congruence transformation, can have the planes of symmetry depending on the location of the center of elasticity. For a plane of symmetry, any vibration mode can be expressed by the axis of vibration. Analytical solutions for the axis of vibration has been derived.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.89-92
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• 2003

A geometrically uniform code in AWGN channel has strong symmetry properties such as a) the distance profiles form codewords On C to all other codewords are all the same, and b) all Voronoi regions of codewords in C have the same shape. Such properties make the word error probability of geometrically uniform codes be transparent to the transmitted codeword. In this paper, we extend the geometrically uniform codes in AWGN channel to the geometrical uniform codes in fading channel with multiple transmit antennas.

• Korean Institute of Interior Design Journal
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• no.26
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• pp.95-103
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• 2001

This study was performed to search for the geometrical principles in modern architecture and design based on Frobel's educational idea and Kindergarten system. Especially, it studies on the geometrical principles of Froebel's building gifts and it's types, and then illustrates applied examples in modern architecture and design. As the architectural scope, the architecture and design theory of Frank Lloyd Wright and Bauhaus in early 20th century is analyzed. The conclusions of this study that starts these purpose are as follows. First, Froebel's educational theory is based on principles and rules which are perceived through the observation of nature, and Froebel's Kindergarten system consists of geometrical building gifts and categories of geometrical forms. Second, the characteristics of Froebel's building gifts are mathematical size, proportion, symmetry and the rules of spatial relation. Third, the influence of Froebel's kindergarten system on Bauhaus is that it based on the rational rules of $\bigtriangleup\square\bigcirc$ organized by geometrical basic forms as like Froebel's educational idea. And the influence of Froebel's Kindergarten system on Frank Lloyd Wright is that he used unit system, unity of space and structure and modular system as like the Froebel's building gifts.