• 한국환경교육학회지:환경교육
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• 제24권4호
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• pp.1-10
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• 2011

The purpose of this study is to investigate effects of environmental education using method of rephrasing lyrics of songs on environmental sensitivity. In order to perform this study, 60 sixth-grade students in an elementary school in Seoul are selected and divided into two groups. Half of the students belong to the experimental group which undergoes environmental education using method of rephrasing lyrics of songs. The others are in the control group which gets traditional environmental education with textbook. A questionnaire was used to survey effects of environmental education using method of rephrasing lyrics of songs. The results of this study are as follows: First, it is found that the environmental education using method of rephrasing lyrics of songs is effective on building up the environmental sensitivity. Second, the environmental education using method of rephrasing lyrics of songs is effective on 4 domains of the environmental sensitivity - positive reception, expectation, disagreeableness and anger for environment and environmental problems. Moreover, the environmental education using method of rephrasing lyrics of songs makes the students in the experimental group have pro-environmental attitudes and behavior. This study revealed that using method of rephrasing lyrics of songs could be effective on the environmental education. Therefore, we have to provide a variety of chances using this method to enhance the environmental sensitivity.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.577-582
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• 2007

A variational formulation for plane elasticity problems is derived based on an isogeometric approach. The isogeometric analysis is an emerging methodology such that the basis functions in analysis domain arc generated directly from NURBS (Non-Uniform Rational B-Splines) geometry. Thus. the solution space can be represented in terms of the same functions to represent the geometry. The coefficients of basis functions or the control variables play the role of degrees-of-freedom. Furthermore, due to h-. p-, and k-refinement schemes, the high order geometric features can be described exactly and easily without tedious re-meshing process. The isogeometric sensitivity analysis method enables us to analyze arbitrarily shaped structures without re-meshing. Also, it provides a precise construction method of finite element model to exactly represent geometry using B-spline base functions in CAD geometric modeling. To obtain precise shape sensitivity, the normal and curvature of boundary should be taken into account in the shape sensitivity expressions. However, in conventional finite element methods, the normal information is inaccurate and the curvature is generally missing due to the use of linear interpolation functions. A continuum-based adjoint sensitivity analysis method using the isogeometric approach is derived for the plane elasticity problems. The conventional shape optimization using the finite element method has some difficulties in the parameterization of boundary. In isogeometric analysis, however, the geometric properties arc already embedded in the B-spline shape functions and control points. The perturbation of control points in isogeometric analysis automatically results in shape changes. Using the conventional finite clement method, the inter-element continuity of the design space is not guaranteed so that the normal vector and curvature arc not accurate enough. On tile other hand, in isogeometric analysis, these values arc continuous over the whole design space so that accurate shape sensitivity can be obtained. Through numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

• 대한기계학회논문집A
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• 제25권1호
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• pp.153-160
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• 2001

A general procedure for the design sensitivity analysis of structural dynamic problems has been presented in frame of the FRF-based substructuring formulation. For a system response function, the proposed method gives a parametric design sensitivity formula in terms of the partial derivatives of the connection element properties and the transfer matrix of the subsystems. The derived design sensitivity formula is applied to an engine mount system. An interior noise problem in the passenger car is analyzed using the FRF-based substructuring method and the proposed formulation is adopted to study the response variations with respect to the dynamic characteristics of the engine mounts and the bushes. To obtain the FRFs, a finite element model is built for the engine mount structures, and test data is used for the trimmed body including cabin cavity. The comparison of sensitivities derived by the proposed method and the finite difference method shows that the proposed method is efficient and accurate. The proposed sensitivity analysis method indicates effectively the most sensitive location to the interior noise among the engine mounts and the bushes.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권7호
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• pp.307-314
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• 2003

This paper presents a 3D shape optimization algorithm for electromagnetic devices using the design sensitivity analysis with finite element method. The structural deformation analysis based on the deformation theory of the elastic body under stress is used for mesh renewing. The design sensitivity and adjoint variable formulae are derived for the 3D finite element method with edge element. The results of sensitivity analysis are used as the input data of the structural analysis to calculate the relocation of the nodal points. This method makes it possible that the new mesh of analysis region can be obtained from the initial mesh without regeneration. The proposed algorithm is applied to the shape optimization of 3D electromagnet pole to net a uniform flux density at the target region.

• Steel and Composite Structures
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• 제15권1호
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• pp.15-39
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• 2013

The sensitivities of a structural response due to variation of its design parameters are prerequisite in the majority of the algorithms used for fundamental problems in engineering as system uncertainties, identification and probabilistic assessments etc. The paper presents the concept of probabilistic sensitivity of suspension bridges with respect to near-fault ground motion. In near field earthquake ground motions, large amplitude spectral accelerations can occur at long periods where many suspension bridges have significant structural response modes. Two different types of suspension bridges, which are Bosporus and Humber bridges, are selected to investigate the near-fault ground motion effects on suspension bridges random response sensitivity analysis. The modulus of elasticity is selected as random design variable. Strong ground motion records of Kocaeli, Northridge and Erzincan earthquakes are selected for the analyses. The stochastic sensitivity displacements and internal forces are determined by using the stochastic sensitivity finite element method and Monte Carlo simulation method. The stochastic sensitivity displacements and responses obtained from the two different suspension bridges subjected to these near-fault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts stochastic sensitivity responses of suspension bridges. The stochastic sensitivity information provides a deeper insight into the structural design and it can be used as a basis for decision-making.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.128-137
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• 1998

A numerical approach for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. Compared with the conventional analytical methods, which require explicit derivation of sensitivity equations, the proposed numerical method can be applied to any type of suspension systems without obtaining sensitivity equations, once any kinematic analysis procedure is established. To obtain sensitivity equations, a numerical differentiation algorithm that uses the third order Lagrange polynomial is developed. The algorithm efficiently and accurately computes the sensitivity of various vehicle static design factors with respect to kinematic design variables. Through a suspension design problem, the validity and usefulness of the method is demonstrated.

• 전산구조공학
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• 제7권1호
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• pp.91-98
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• 1994

선박, 자동차, 항공기등 수송체 구조해석에 유한요소법이 사용됨에 따라 초기 설계 후 대형 복합구조물의 해석이 ANSYS, NASTRA등의 범용 유한요소 코드에 의해 수행되고 있다. 설계변경을 시도할 때 설계자의 경험과 인지만으로 대형 구조물의 성능변경을 예측하기는 어렵다. 비록 대형 컴퓨터의 사용으로 구조 재해석이 용이하나 정량적 및 이론적 설계수정방향 없이는 인력과 계산시간 소모를 초래하고 때로는 시간 제약으로 충분한 재해석을 못할 수가 있다. 이때 긴요하게 사용될 수 있는 정보는 민감도로서 설계변수 변화에 대한 구조응답 변화를 수치적으로 나타내므로 설계변경에 도움을 줄 수 있다. 본 논문에서 계산된 정확한 민감도는 선체데크구조와 수송체구조물 프레임 강성도를 설계 변수로 하였으며 구조물 진동저감 설계에 사용될 수 있다. 즉 유한요소법에 의한 구조 재해석에 의하지 않고 민감도 값으로 구조 진동변위 증감을 예측할 수 있음이 예제로 보여지고 있다.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4685-4694
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• 2023

The ability to calculate the material density sensitivity coefficients of power with respect to the material density has broad application prospects for accelerating Monte Carlo-Thermal Hydraulics iterations. The second-order material density sensitivity coefficients for the general Monte Carlo score have been derived based on the differential operator sampling method in this paper, and the calculation of the sensitivity coefficients of cell power scores with respect to the material density has been realized in continuous-energy Monte Carlo code RMC. Based on the power-density sensitivity coefficients, the sensitivity coefficients of power scores to some other physical quantities, such as power-boron concentration coefficients and power-temperature coefficients considering only the thermal expansion, were subsequently calculated. The effectiveness of the proposed method is demonstrated in the power-density coefficients problems of the pressurized water reactor (PWR) moderator and the heat pipe reactor (HPR) reflectors. The calculations were carried out using RMC and the ENDF/B-VII.1 neutron nuclear data. It is shown that the calculated sensitivity coefficients can be used to predict the power scores accurately over a wide range of boron concentration of the PWR moderator and a wide range of temperature of HPR reflectors.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.237-244
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• 2002

Analyzing acoustic-structural systems such as automobiles and aircraft, the FRF-based substructuring (FBS) method is one of the most powerful tools. In this paper, a general procedure for the parametric sensitivity analysis of vibro-acoustic problems has been presented using the multi-domain FRF-based substructuring formulation. For an acoustic-structural system sub-structured by multiple domains, the substructuring formulation gives the reaction farces on the interface boundaries. The design sensitivity formula is obtained from the direct differentiation of the reaction force expression with respect to the design vector. As a practical application, the proposed design sensitivity formula is applied to an engine mount system of passenger car. An objective of the problem is to identify the most effective engine mounts and bushes in minimizing the interior noise over the concerned rpm range. The comparison of the sensitivity results with those of the finite difference method shows excellent agreement. In addition, stiffness modifications of the mounts and bushes identified through the design sensitivity analysis lead to a successful decrease of the interior noise. This results show usefulness of the present method very well.

• Journal of Mechanical Science and Technology
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• 제14권2호
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• pp.197-206
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• 2000

A boundary integral equation method in the shape design sensitivity analysis is developed for the elasticity problems with axisymmetric non-homogeneous bodies. Functionals involving displacements and tractions at the zonal interface are considered. Sensitivity formula in terms of the interface shape variation is then derived by taking derivative of the boundary integral identity. Adjoint problem is defined such that displacement and traction discontinuity is imposed at the interface. Analytic example for a compound cylinder is taken to show the validity of the derived sensitivity formula. In the numerical implementation, solutions at the interface for the primal and adjoint system are used for the sensitivity. While the BEM is a natural tool for the solution, more generalization should be made since it should handle the jump conditions at the interface. Accuracy of the sensitivity is evaluated numerically by the same compound cylinder problem. The endosseous implant-bone interface problem is considered next as a practical application, in which the stress value is of great importance for successful osseointegration at the interface. As a preliminary step, a simple model with tapered cylinder is considered in this paper. Numerical accuracy is shown to be excellent which promises that the method can be used as an efficient and reliable tool in the optimization procedure for the implant design. Though only the axisymmetric problem is considered here, the method can be applied to general elasticity problems having interface.