• Transactions on Electrical and Electronic Materials
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• 제15권4호
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• pp.182-188
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• 2014

When the windowed DFT algorithm is applied in harmonic measurements, the problem of initial-phase sensitivity will be encountered, this has an effect on harmonic amplitude accuracy. In this paper, the origin of initial-phase sensitivity is analyzed and the main factors that influence the level of initial-phase sensitivity are demonstrated. A method of reducing initial-phase sensitivity is proposed to increase the stability of harmonic measurements. We found that initial-phase sensitivity is determined by the side lobe peak level of the window functions when synchronous deviation is fixed. In addition, increasing the length of the time recorded can be used to remove initial-phase sensitivity. The correctness and validity of our conclusions have been confirmed through numerical results and field tests.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.355-362
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• 2004

An efficient boundary-based technique is developed for addressing shape design sensitivity analysis in various problems. An analytical sensitivity formula in the form of a boundary integral is derived based on the continuum formulation for a general functional defined in problems. The formula, which is expressed in terms of the boundary solutions and shape variation vectors, can be conveniently used for gradient computation in a variety of shape design problems. While the sensitivity can be calculated independent of the analysis means, such as the finite element method (FEM) or the boundary element method (BEM), the FEM is used for the analysis in this study because of its popularity and easy-to-use features. The advantage of using a boundary-based method is that the shape variation vectors are needed only on the boundary, not over the whole domain. The boundary shape variation vectors are conveniently computed by using finite perturbations of the shape geometry instead of complex analytical differentiation of the geometry functions. The supercavitating flow problem and fillet problem are chosen to illustrate the efficiency of the proposed methodology. Implementation issues for the sensitivity analysis and optimization procedure are also addressed in these problems.

• International Journal of Human Ecology
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• 제13권1호
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• pp.39-56
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• 2012

This study aims at exploring Korean mothers' beliefs on the development of emotion of their children. In specific, sensitivity and maternal reactions to their children's both negative and positive emotion expressions were explored. Further, associations among maternal sensitivity, maternal reactions and child emotion regulation were examined. A total of 100 Korean mothers whose children were between 6 and 7 years old participated in the study. In order to assess mothers' beliefs about sensitivity, vignettes in a forced-choice format were presented through individual interviews. Mothers' self reported reactions to their children's negative emotions and positive emotions and mothers' perceptions of children's emotion regulation were assessed using questionnaires. Results revealed that Korean mothers endorsed both proactive and reactive sensitivity. However, their sensitivity differed depending on the situation. Mothers tended to endorse either Emotion Focused or Problem Focused reactions to their children's negative emotions. Mothers reported that they were most likely to restrict their child positive emotional expression with explanation in supportive way followed by invalidating through reprimanding it. Mothers' reported Distress Reactions and Punitive Reactions to children's expression of negative emotion were associated with children's liability whereas Emotion-Focused Reaction and Problem-Focused Reaction were associated with children's functional emotion regulation. The results are discussed within a theoretical framework of socialization of emotions.

• Structural Engineering and Mechanics
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• 제56권5호
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• pp.871-897
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• 2015

This paper presents a novel method based on sensitivity of structural response for identifying both the system parameters and input excitation force of a bridge. This method, referred to as "Adjoint Variable Method", is a sensitivity-based finite element model updating method. The computational cost of sensitivity analyses is the main concern associated with damage detection by these methods. The main advantage of proposed method is inclusion of an analytical method to augment the accuracy and speed of the solution. The reliable performance of the method to precisely indentify the location and intensity of all types of predetermined single, multiple and random damages over the whole domain of moving vehicle speed is shown. A comparison study is also carried out to demonstrate the relative effectiveness and upgraded performance of the proposed method in comparison to the similar ordinary sensitivity analysis methods. Moreover, various sources of error including the effects of noise and primary errors on the numerical stability of the proposed method are discussed.

• Journal of Advanced Marine Engineering and Technology
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• 제22권4호
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• pp.560-568
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• 1998

Recently to develop an automobile with better properities many researches and investments have been executed. In this paper we intend to improve the automobile properties by reducing the weight of the engine without changing the dynamic characteristics. At first the vibration analysis by the Substructure Synthesis Mehtod and the exciting test of the engine model performed to confirm the reliability of the analyzing tools. And the weight minimiza-tion is performed by the Sensitivity Analysis and the Optimum Structural Modificationl. To decrease the engine weight ideally the weight of the parts with the low sensitivity is to cut mainly and the changing quantity of the natural frequency by the cut is to be recovered by the weight modification of the parts with the high sensitivity. As actually the mathematical unique solution for the homogeneous problem(i. e. 0 object func-tion problem)does not exist we redesign the engine block with much thinner initial thickness and recover the natural frequencies and natural modes of original structure by the sensitivity analy-sis and then observe the Frequency Response Function(FRF) for the interesting points. In this analysis the original thickness of the engine model is 8mm and the redesigned initial thicknesses are 5mm and 6mm, And the number of the interesting natural frequencies are 1, 2, 3, 4 and 5 respectively.

• Structural Engineering and Mechanics
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• 제54권6호
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• pp.1217-1244
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• 2015

In this research a theoretical and numerical study on a bridge damage detection procedure is presented based on vibration measurements collected from a set of accelerometers. This method, referred to as "Adjoint Variable Method", is a sensitivity-based finite element model updating method. The approach relies on minimizing a penalty function, which usually consists of the errors between the measured quantities and the corresponding predictions attained from the model. Moving mass is an interactive model and includes inertia effects between the model and mass. This interactive model is a time varying system and the proposed method is capable of detecting damage in this variable system. Robustness of the proposed method is illustrated by correct detection of the location and extension of predetermined single, multiple and random damages in all ranges of speed and mass ratio of moving vehicle. A comparative study on common sensitivity and the proposed method confirms its efficiency and performance improvement in sensitivity-based damage detection methods. In addition various possible sources of error, including the effects of measurement noise and initial assumption error in stability of method are also discussed.

• 전기학회논문지
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• 제62권1호
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• pp.49-56
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• 2013

In this paper, for constrained optimization problem, one multi-objective optimization algorithm that ensures both performance robustness and constraint feasibility is proposed when uncertainties are involved in design variables. In the proposed algorithm, the gradient index of objective function assisted by design sensitivity with the help of finite element method is applied to evaluate robustness; the reliability calculated by the sensitivity-assisted Monte Carlo simulation method is used to assess the feasibility of constraint function. As a demonstration, the performance and numerical efficiency of the proposed method is investigated through application to the optimal design of TEAM problem 22--a superconducting magnetic energy storage system.

• 아동학회지
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• 제28권6호
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• pp.183-199
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• 2007

This longitudinal study investigated developmental changes in temperament and examined social adjustment problems by early temperamental characteristics and developmental patterns of temperamental change during infancy. Subjects were 153 six-month-old infants and their mothers. Infant temperament and toddler's problem behavior were measured by the Infant Behavior Questionnaire-Revised (Garstein & Rothbart, 2003) and the Toddler Behavior Checklist (Larzelere et al., 1989), respectively. Results showed that distress to limitations, high pleasure, perceptual sensitivity, and approach increased with age, while activity level, cuddliness, and vocal reactivity decreased. Infants with high scores in activity level, fear, sadness, and approach at 6 months showed more problem behaviors at 18 months. Infants showing abrupt developmental change of high pleasure and perceptual sensitivity developed more negative behavior.

• 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.

• 정보화정책
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• 제24권2호
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• pp.68-86
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• 2017

본 연구는 한국정보화진흥원에서 주관하는 월드프렌즈 IT봉사단의 성과지표로서 단원들의 '역량(문제해결능력, 셀프리더쉽), 인성(자아효능감), 인적네트워크(문화 간 감수성)'의 변화와 개인별 특성에 따른 성과 차이를 알아보고자 2016년에 모집되어 개도국에 파견된 IT봉사단 364명을 대상으로 사전 검사, 봉사 활동 수행, 사후 검사를 실시하였다. 그리고 수집된 자료는 사전검사의 결과를 공변수로 하여 공분산분석(ANCOVA)으로 검증하였다. 그 결과, 단원들은 문제해결력, 셀프 리더쉽, 문화 간 감수성이 향상된 것으로 나타났다. 또한 개인적 특성별로 보면, 여학생이 남학생보다 문화 간 감수성이, 남학생이 여학생보다 자아효능감이, 영어의사소통능력이 높은 학생이 낮은 학생보다 문화 간 감수성과 셀프 리더쉽이 향상되었다. 또한 단기체류 유경험자가 무경험자보다 문제해결력과 문화 간 감수성이, 장기체류 유경험자가 무경험자보다 문화 간 감수성이 높아진 것으로 나타났다. 그리고 리더 역할을 담당한 단원이 팀원들보다 자아효능감이 향상되는 것으로 확인되었다.