• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.453-457
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• 2006

This study predicts the modified structure of eigenvectors and eigenvalues due to the changes in the mass and the stiffness of the structure. The sensitivity method of natural frequency using partial differential are derived with respect to the physical parameter to calculate the structure modification. The method are applied to the 3 degree of freedom???slumped mass model by modeling the mass and stiffness, and then applies the method to a real crankshaft system. The position, direction of parameter change and modified value were predicted for modification. Finally the predicted value is used to investigate the magnitude of vibration and we found that the effect of modification results to reduce the level of magnitude vibration is satisfactory.

• 한국항해학회지
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• 제25권1호
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• pp.45-52
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• 2001

본 논문은 선체구조에 많이 이용되고 있는 보강판 구조물의 동적 특성을 최적 변경하는데 그 목적이 있다. 유한요소법(FEM), 동적 감도해석법, 최적구조 변경법을 이용하여 보강판의 동적 특성을 최적화한다. 먼저, FEM을 이용하여 보강판 구조물의 동적 특성을 해석한다. 다음으로 설계변수의 변화에 따른 동적 특성의 변화율을 동적 감도해석법으로 해석한다. 감도해석법으로 구한 감도값과 최적구조 변경법을 이용하여 설계변수들의 변경 량을 계산한다. 보강판 구조물의 고유진동수의 변경을 목적함수로 하고, 보강판의 두께와 보강재의 단면2차 모우멘트를 설계 변수로 한다. 본 논문에서 이용한 최적구조 변경법이 보강판 구조물의 동특성을 최적화하는데 유용함을 보여준다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.364-369
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• 1997

It is very difficult to execute the vibration analysis of a huge structure, which takes up much time and expense. In this paper we intend to make the equivalent system of a local vibration system of a huge structure with a view to improving the dynamic characteristics and reducing time and expense. First of all, upper deck structure model is maded. And we perform the vibration analysis by the Substructure Synthesis Method and execute the exciting test for the upper deck structure model, and observe the coincidences of two results to confirm the reliability of the analyzing tools used. To make the equivalent system, we give boundary condition to sub-structure that want to be modified and execute the Sensitivity Analysis Method and the Optimum Structural Modification Method. And we execute the structural modification of the equivalent system.

• 한국분말재료학회지
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• 제6권1호
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• pp.36-41
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• 1999

The present work has attempted to investigate the dependence of Cu infiltration kinetics on in-situ structure modification of W powder skeleton in W-Cu system. In-situ structure modification of W skeleton by addition of 0.3wt%Ni-P eutectic alloy was designed to proceed during heat-up of the W compact for Cu infiltration process. It was found that the Ni-P added W skeleton underwent remarkable stucture change only during heating-up. its structure was composed of large necks of W particles above 0.5 in the ratio of neck to particle size and smooth pore channels. The infiltration experiment showed that the infiltration kinetics for the W-Ni-P followed well the linear relationship of h vs. $t^{1/2}$ the rate constant K of which was in good agreement with the theoretical value. On the other hand, in case of the pure W skeleton a lower K value by 20% than the theoretical one was obatined. Such discrepancy is discussed in terms of skeleton structure induced infiltration mechanics.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.48-58
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• 2002

There is a purpose of this study for the proposal of the optimum technique utilized for the vibration design initial step. The stiffened plate structure for the ship hull is made for analysis model. To begin with, dynamic characteristics of stiffened plate structure is analysed using FEM. Main vibrational mode of the structure is decided in the analytical result of FEM. The simplified equation on the natural frequency of the main vibrational mode is induced. Next, sensitivity analysis is carried out using the simplified equation, and rate of change of dynamic characteristics is calculated. Then, amount of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of panel, cross section moment of stiffener and girder become a design variable. The validity of the optimization method using simplified equation is examined. It is shown that the result effective in the optimum modification for natural frequency of the stiffened plate structure.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제3권1호
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• pp.33-40
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• 1996

A convergence structure defined by Kent [4] is a correspondence between the filters on a given set X and the subsets of X which specifies which filters converge to points of X. This concept is defined to include types of convergence which are more general than that defined by specifying a topology on X. Thus, a convergence structure may be regarded as a generalization of a topology. With a given convergence structure q on a set X, Kent [4] introduced associated convergence structures which are called a topological modification and a pretopological modification. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.354-359
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• 2012

Improvement of structure-borne noises in the vehicle compartments has been one of the primary concerns in the development of vehicles. The booming is an annoying low frequency interior noise and vibration in vehicle. But it is difficult to reduce the structure-born booming noise in traditional method - trial and error within the shorten development schedule. So in present, the structure dynamic modification (SDM) method helpful to predict the effect of the local mass, stiffness, and damping is introduced. So in order to reduce the interior booming noise, the SDM was performed, and verified with modal test result. It was shown that the interior booming noise was reduced as predicted.

• 한국산학기술학회논문지
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• 제12권1호
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• pp.45-54
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• 2011

본 논문은 소형 냉동 시스템에서 왕복동식 압축기는 주요한 진동원이자 소음원으로서 압축기의 외부 구조 동특성을 변경함으로써, 진동과 소음을 줄이는 방법에 관한 것이다. 구조 동특성의 변경은 유한요소 모델에 의한 해석적 방법을 적용하고, 구조 변경의 시도는 두 유한요소들 간의 모드합성법(CMS)을 적용한다. 효과적인 CMS의 적용방법을 찾아내고, 이 방법에 대하여 압축기 모델에 대한 실험적 검증을 통하여 검증하였다.

• 대한수학회논문집
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• 제11권4호
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• pp.1087-1094
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• 1996

In this paper, we introduce the notion of the n-th pretopological modification. Also, we find some properties which hold between convergence quotient maps and n-th pretopological modifications.

• East Asian mathematical journal
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• 제17권2호
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• pp.217-224
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• 2001

In this paper, we introduce the notion of some modification of given convergence structure and product convergence. Also, we find some properties which hold between the modification associated with a product of convergence structures and the product of modifications associated with the factor convergence structures.