• Computational Structural Engineering
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• v.9 no.4
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• pp.117-126
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• 1996

Damage detection methods using structural tests can be divided into two methods, i.e., static and dynamic. The static methods which use the stiffness properties of the structure are simpler than the dynamic methods. However, static approaches are very sensitive to the displacement measurement noises and modeling errors. The dynamic methods also have limitations in acquiring the natural frequencies and mode shapes of the high frequencies. In this study, a method for the structural damage assessment using sensitivity matrices is developed, in which the drawbacks of the static and dynamic methods can be compensated. Based on the measurement data for the static displacements and dynamic modal properties, the damage locations and the degree of damage are determined using the presented sensitivity matrix method. The efficiency of the proposed method has been examined through numerical simulation studies on truss type structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2727-2734
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• 2013

This study was designed to examine the effect of maternal attachment of infant and parenting efficacy on infant-mother's interaction. The subject were 180 infant and their mother who were early childhood education service in G city. Data analysed with Pearson correlation, regression. The results were as follows. First, there were showed tendency of normal level that mother's attachment and parenting efficacy to infant, infant-mother's interactions. Second, there were significant positive relationships between the mother's attachment of infant and infant-mother's interactions. Third, there were significant positive relationships between the mother's parenting efficacy and infant-mother's interactions. Fourth, the mother's attachment of infant and parenting efficacy has effect on the infant-mother's interactions.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.402-407
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• 2001

Sensitivity analysis scheme is developed in the elasto-plastic finite element method with explicit time integration using direct differentiation method. The direct differentiation is concerned with the time integration, constitutive relation, shell element with reduced integration and the contact scheme. Sensitivity analysis results are mainly examined with the highly nonlinear and quasi-static problem with the complicated contact condition. The result shows stable sensitivity especially in the sheet metal forming analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.108-116
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• 2017

In this study, the prototype structure of seismically designed steel moment frame was analyzed statically and dynamically in order to demonstrate the applicability of energy-based approximate analysis with the dynamic effect of sudden column loss in the evaluation of the collapse resistance and a method for assessing the sensitivity to progressive collapse was proposed. For the purpose of comparing the structural behavior of buildings with different structural systems, the sensitivity of the structure to the sudden removal of vertical members can be used as a significant measure. The energy-based approximate analysis prediction for the prototype structure considered in the study showed good agreement with the dynamic analysis result. In the sensitivity evaluation, the structural robustness index that indicates the ability of a structure to resist collapse induced by abnormal loads was used. It was confirmed that the proposed methods can be used conveniently and rationally in progressive collapse analysis and design.

• Journal of KIISE:Software and Applications
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• v.27 no.9
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• pp.986-1002
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• 2000

정적 분석을 사용하여 프로그램의 입력에 의존하는 성질을 예측하는 방법을 제안한다. 제안된 방법은 입력에 무관한 성질을 예측하도록 설계된 정적 분석을 입력에 의존하는 성질을 예측하는 분석으로 변환한다. 이 방법은 실행 중에 프로그램의 성질을 알아내기 위해서 실행중인 프로그램을 관찰하는 코드가 필요 없고 계측된 자료를 모으는 과정도 필요 없다. 정적 분석의 가장 마지막 부분을 프로그램의 실행 시간으로 미루는 것이 이 논문의 핵심 아이디어다. 먼저 정적 분석을 분석하여, 프로그램의 입력에 민감하여 프로그램의 실행시간으로 연기되어야 하는 부분을 찾아낸다. 그 후, 값을 자른 분석을 사용하여 이 부분을 재구성하여 프로그램의 입력에 대한 간단한 멤버쉽 테스트에 의해 분석이 풀어질 수 있도록 한다. 이런 재구성 과정을 통해 준비된 분석들은 프로그램의 입력이 나타나기만 하면 순간적으로, 동시에 풀려질 수 있다. 모든 과정은 엄밀하게 정의되고 증명되었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.3
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• pp.264-273
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• 1984

초기경향이 있는 보강평판의 비선형 운동 방정식을 Galerkin method에 의하여 유도하였다. Runge Kutta method를 사용하여 step-load를 받고 있는 보강평판의 동적 좌굴문제의 수치해를 구하였다. 정적 좌굴실험에 의하여 좌굴하중을 결정함에 있어 동적 해석법을 응용할 수 있음을 입증하였으며, step-load를 받는 보강평판의 동적 좌굴해석으로 정적좌굴의 초기결함 민감성을 해 석하였다. 보강평판의 초기결함민강성은 평판보다 훨씬 낮으며 보강재의 편심비가 높을수록 민감 성은 둔화된다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1088-1094
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• 1997

An indirect cutting torque and cutting force estimation method is presented. This method uses a time-domain model between the spindle motor power, which calculated form measured spindle motor current and voltage. Spindle motor power is linear with cutting torque in this model. The cutting force is proportional to the cutting torque. Using trial cut, parameters are determined. Static sensitivity is suitable for various cutting conditions. The presented method is verified under several cutting tests on the CNC horizontal machining center.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.150-156
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• 1996

Static variations of cutting forces are estimated using spindle motor current. Static sensitivity of spindle motor current is higher than feed motor current. The linear relationship between the cutting force and RMS value of the spindle motor current is obtained. Using cutting force estimation, tool overload in milling process can be well detected, and cutting force is regulated at a constant level by feedrate adaptive control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1811-1820
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• 2010

Most components in the real world show nonlinear response. The nonlinearity may arise because of contact between the parts, nonlinear material, or large deformation of the components. Structural optimization considering nonlinearities is fairly expensive because sensitivity information is difficult to calculate. To overcome this difficulty, the equivalent load method was proposed for nonlinear response optimization. This method was originally developed for size and shape optimization. In this study, the equivalent load method is modified to perform topology optimization considering all kinds of nonlinearities. Equivalent load is defined as the load for linear analysis that generates the same response field as that for nonlinear analysis. A simple example demonstrates that results of the topology optimization using equivalent load are very similar to the numerical results. Nonlinear response topology optimization is performed with a practical example and the results are compared with those of conventional linear response topology optimization.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.641-646
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• 2002

A new damage detection technique using static displacement data was developed, in order to assess the structural integrity of bridge structures. In conventional damage assessment techniques using dynamic response, the variation of natural frequencies is intrinsically insensitive to the damage of the bridge: thus, it is usually difficult to obtain them from the measured data. The proposed detection method enables the estimation of the stiffness reduction of bridges using the static displacement data that are measured periodically, without requiring a specific loading test. Devices such as a laser displacement sensor can be used to measure static displacement data due to the dead load of the bridge structure. In this study, structural damage was represented by the reduction in the elastic modulus of the element. The damage factor of the element was introduced to estimate the stiffness reduction of the bridge under consideration. Likewise, the proposed algorithm was verified using various numerical simulations and compared with other damage detection methods. The effects of noise and number of damaged elements on damage detection were also investigated. Results showed that the proposed algorithm efficiently detects damage on the bridge.