• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.181-186
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• 1998

A modelling method for the vibration analysis of rotating cantilever plates with a concentrated mass is presented. The equations of motion for the rotating plates with a concentrated mass located in an arbitrary position are derived. For the modelling of the concentrated mass, a mass density Dirac delta function is used. The effects of concentrated mass and its location, angular speed, and hub radius of the rotating plate on the natural frequencies are studied. Particularly, mode shape variations due to some parameter variations are investigated.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1031-1041
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• 1999

기존의 한글에 대한 입술 애니메이션 방법은 음소의 입모양을 몇 개의 입모양으로 정의하고 이들을 보간하여 입술을 애니메이션하였다. 하지만 발음하는 동안의 실제 입술 움직임은 선형함수나 단순한 비선형함수가 아니기 때문에 보간방법에 의해 중간 움직임을 생성하는 방법으로는 음소의 입술 움직임을 효과적으로 생성할 수 없다. 또 이 방법은 동시조음도 고려하지 않아 음소들간에 변화하는 입술 움직임도 표현할 수 없었다. 본 논문에서는 동시조음을 고려하여 한글을 자연스럽게 발음하는 입술 애니메이션 방법을 제안한다. 비디오 카메라로 발음하는 동안의 음소의 움직임들을 측정하고 입술 움직임 제어 파라미터들을 추출한다. 각각의 제어 파라미터들은 L fqvist의 스피치 생성 제스처 이론(speech production gesture theory)을 이용하여 실제 음소의 입술 움직임에 근사한 움직임인 지배함수(dominance function)들로 정의되고 입술 움직임을 애니메이션할 때 사용된다. 또, 각 지배함수들은 혼합함수(blending function)와 반음절에 의한 한글 합성 규칙을 사용하여 결합하고 동시조음이 적용된 한글을 발음하게 된다. 따라서 스피치 생성 제스처 이론을 이용하여 입술 움직임 모델을 구현한 방법은 기존의 보간에 의해 중간 움직임을 생성한 방법보다 실제 움직임에 근사한 움직임을 생성하고 동시조음도 고려한 움직임을 보여준다.Abstract The existing lip animation method of Hangul classifies the shape of lips with a few shapes and implements the lip animation with interpolating them. However it doesn't represent natural lip animation because the function of the real motion of lips, during articulation, isn't linear or simple non-linear function. It doesn't also represent the motion of lips varying among phonemes because it doesn't consider coarticulation. In this paper we present a new coarticulation model for the natural lip animation of Hangul. Using two video cameras, we film the speaker's lips and extract the lip control parameters. Each lip control parameter is defined as dominance function by using L fqvist's speech production gesture theory. This dominance function approximates to the real lip animation of a phoneme during articulation of one and is used when lip animation is implemented. Each dominance function combines into blending function by using Hangul composition rule based on demi-syllable. Then the lip animation of our coarticulation model represents natural motion of lips. Therefore our coarticulation model approximates to real lip motion rather than the existing model and represents the natural lip motion considered coarticulation.

• Smart Structures and Systems
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• v.16 no.5
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• pp.891-918
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• 2015

In many of microdevices a part of a microbeam is covered by a piezoelectric layer. Depend on the application a DC or AC voltage is applied between upper and lower side of the piezoelectric layer. A common method in many of previous works for evaluating the response of these structures is discretizing by Galerkin method. In these works often single mode shape of a uniform microbeam i.e. the microbeam without piezoelectric layer has been used as comparison function, and so the convergence of the solution has not been verified. In this paper the Galerkin method is used for discretization, and a comprehensive analysis on the convergence of solution of equation that is discretized using this comparison function is studied for both clamped-clamped and clamped-free microbeams. The static and dynamic solution resulted from Galerkin method is compared to the modal expansion solution. In addition the static solution is compared to an exact solution. It is denoted that the required numbers of uniform microbeam mode shapes for convergence of static solution due to DC voltage depends on the position and thickness of deposited piezoelectric layer. It is shown that when the clamped-clamped microbeam is coated symmetrically by piezoelectric layer, then the convergence for static solution may be obtained using only first mode. This result is valid for clamped-free case when it is covered by piezoelectric layer from left clamped side to the right. It is shown that when voltage is AC then the number of required uniform microbeam shape mode for convergence is much more than the number of required mode in modal expansion due to the dynamic effect of piezoelectric layer. This difference increases by increasing the piezoelectric thickness, the closeness of the excitation frequency to natural frequency and decreasing the damping coefficient. This condition is often indefeasible in microresonator system. It is concluded that discreitizing the equation of motion using one mode shape of uniform microbeam as comparison function in many of previous works causes considerable errors.

• Smart Structures and Systems
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• v.4 no.3
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• pp.343-365
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• 2008

In this study, the frequency domain method which utilizes the evaluation of changes in the structural mode shape is adopted to identify regions which contain localized damages. Frequency response function (FRF) values corresponding to the modal frequency, analogous to the mode shape coefficients, are used since change in natural frequency of the system is usually insignificant for localized damage. This method requires only few sensors to obtain the dynamic response of the structure at specific locations to determine the FRF via fast-Fourier transform (FFT). Numerical examples of an aluminum plate, which includes damages of varying severity, locations and combinations of multiple locations, are presented to demonstrate the feasibility of the method. An experimental verification of the method is also done using an aluminum plate with two different degrees of damage, namely a half-through notch and a through notch. The inconsistency in attaining the FRF values for practical applications due to varying impact load may be overcome via statistical averaging, although large variations in the loading in terms of the contact duration should still be avoided. Nonetheless, this method needs special attention when the damages induce notable changes in the modal frequency, such as when the damages are of high severity or cover more extensive area or near the boundary where the support condition is modified. This is largely due to the significant decrease in the frequency term compared to the increase in the vibration amplitude. For practical reasons such as the use of limited number of sensors and to facilitate automation, extending the resolution of this method of identification may not be efficient. Hence, methods based on wave propagation can be employed as a complement on the isolated region to provide an accurate localization as well as to trace the geometry of the damage.

• Steel and Composite Structures
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• v.28 no.5
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• pp.589-606
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• 2018

The previous studies reflected the significant effect of neutral-axis position and coupling of in-plane and out-of-plane displacements on behavior of functionally graded (FG) nanobeams. In thin FG beam, this coupling can be eliminated by a proper choice of the reference axis. In shear deformable FG nanobeam, not only this coupling can't be eliminated but also the position of neutral-axis is dependent on through-thickness distribution of shear strain. For the first time, in this paper it is avoided to guess a shear strain shape function and the exact shape function and consequently the exact position of neutral axis for arbitrary gradation of higher order nanobeam are obtained. This paper presents new methodology based on differential transform and collocation methods to solve coupled partial differential equations of motion without any simplifications. Using exact position of neutral axis and higher order beam kinematics as well as satisfying equilibrium equations and traction-free conditions without shear correction factor requirement yields to better results in comparison to the previously published results in literature. The classical rule of mixture and Mori-Tanaka homogenization scheme are considered. The Eringen's nonlocal continuum theory is applied to capture the small scale effects. For the first time, the dependency of exact position of neutral axis on length to thickness ratio is investigated. The effects of small scale, length to thickness ratio, Poisson's ratio, inhomogeneity of materials and various end conditions on vibration and buckling of local and nonlocal FG beams are investigated. Moreover, the effect of axial load on natural frequencies of the first modes is examined. After degeneration of the governing equations, the exact new formulas for homogeneous nanobeams are computed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.4
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• pp.370-380
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• 2002

This paper proposes an ATR (Automatic Target Recognition) algorithm for identifying non-occluded and occluded military vehicles in natural FLIR (Forward Looking InfraRed) images. After segmenting a target, a radial function is defined from the target boundary to extract global shape features. Also, to extract local shape features of upper region of a target, a distance function is defined from boundary points and a line between two extreme points. From two functions and target contour, four global and four local shape features are proposed. They are much more invariant to translation, rotation and scale transform than traditional feature sets. In the experiments, we show that the proposed feature set is superior to the traditional feature sets with respect to the similarity-transform invariance and recognition performance.

• Structural Engineering and Mechanics
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• v.68 no.4
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• pp.399-408
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• 2018

Cable supported structures have been widely used in civil engineering. Cable tension estimation has great importance in cable supported structures' analysis, ranging from design to construction and from inspection to maintenance. Even though the Bernoulli-Euler beam element is commonly used in the traditional finite element method for calculation of frequency and cable tension estimation, many elements must be meshed to achieve accurate results, leading to expensive computation. To improve the accuracy and efficiency, a dynamic finite element method for estimation of cable tension is proposed. In this method, following the dynamic stiffness matrix method, frequency-dependent shape functions are adopted to derive the stiffness and mass matrices of an exact beam element that can be used for natural frequency calculation and cable tension estimation. An iterative algorithm is used for the exact beam element to determine both the exact natural frequencies and the cable tension. Illustrative examples show that, compared with the cable tension estimation method using the conventional beam element, the proposed method has a distinct advantage regarding the accuracy and the computational time.

• Journal of KSNVE
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• v.10 no.2
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• pp.312-318
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• 2000

A modeling method for the vibration analysis of rotating cantilever plastes with stiffeners is presented. The equations of motion for the plates aer derived and trnasformed into a dimensionless form. A mass density Dirac's delta function is used to idealize the stiffener mathematically. The effects of stiffeners on the model characteristics of the plate are investigated, and mode shape variations due to some parameter variation are exhibited. It is found that veering phenomena occur between some loci and associated mode shapes change significantly during the veering phenomena.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.476-490
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• 2016

This paper defines mode shape function of a composite solar panel assumed as Kirchhoff-Love plate for considering a torsional mode of composite solar panel. It then goes on to define dynamic model of a high-agility satellite considering the flexibility of composite solar panel as well as stiffness of a solar panel's hinge using Lagrange's theorem, Ritz method and the mode shape function. Furthermore, this paper verifies the validity of dynamic model by comparing numerical results from the finite element analysis. In addition, this paper performs a dynamic response analysis of a rigid satellite which includes only natural modes for solar panel's hinges and a flexible satellite which includes not only natural modes of solar panel's hinges, but also structural modes of composite solar panels. According to the results, we confirm that the torsional mode of solar panel should be considered for the structural design of high-agility satellite. Finally, we performed optimization of high-agility satellite for minimizing mass with solar panel's area limit using the defined dynamic model. Consequently, we observed that the defined dynamic model for a high-agility satellite and result of the optimal design are very useful not only because of their optimal structural design but also because of the dynamic analysis of the satellite.

• Journal of the Korean Society of Costume
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• v.51 no.2
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• pp.93-103
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• 2001

This Study shows local characters, meaning, value and others (kind, function, material, shape, name) on Shroud through documents and fact-finding survey. In Shroud′s kind and function, Shroud of Kwangju Area is similar with one of Youngsan-river Area, while Sumjin-river Area and Coastal Area, each has its own character due to difference of Burial Culture. In Shroud′s Material, hemp cloth, white cotton cloth and calico, have been well-used in Kwangju and Youngsan-river Area, while silk has used in Sumjin-river and Coastal Area. Shroud′s color has followed Natural color. In Shroud′s shape, Male Jeoksam, Female Trousers, Um, Myokmok, Aksoo, Bib have their local characters. They are reformed in Kwangju Area and Youngsan-river Area. Jeoksam in Coastal Area, Female Trousers in Sumjin-river Area. Um in Coastal Area and Myokmok in Sumjin-river Area, have its unique character. In Shroud′s name, Shroud has widely been called "Dead Clothes", and called "Blind Clothes", "Munnyung Clothes" some areas. In Sumjin-river Area, Summer Jacket has been failed "Deungjigae", Dango called "Ddangjungwee". In Coastal Area, Myokmok and Aksoo have been called "Face Cover" and "Hands Cover", Shroud′s local characters have been caused by Next World, which has reflected local natural environment and cultural features. Next World is so abstract that it can not be expressed well, while Reality is clearly divided into dual spaces : Real World, Next World. Comprehension on Next World, helps harmonize recent values with Shroud meaning and prevents Shroud from standardization and transformation.