• Computational Structural Engineering
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• v.17 no.2
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• pp.42-49
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• 2004

강체스프링 모델은 분할된 요소를 강체라고 가정하고, 각 요소는 스프링 시스템을 연결되어 있다고 생각하여 구조물을 해석하는 방법이다. 먼저 보의 휨 문제에 대한 강체스프링 모델의 개념을 설명하고자 한다. (중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.84-90
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• 2018

In constructing the multi-body dynamics model to analyze the behavior of the railway vehicle, it is very important to understand the properties of the suspension elements that constitute the suspension system. Among them, coil springs, which are mainly used in primary and secondary suspension systems, clearly show the axial stiffness in the drawings, but the lateral properties of the coil springs are not specified clearly, making it difficult to construct a dynamic analysis model. Therefore, in this paper, the model for analyzing the lateral stiffness of the coil spring is examined. A finite element method was applied to analyze the lateral stiffness of the coil spring and numerical analysis was performed by applying the coil spring lateral stiffness analysis model proposed by Krettek and Sobczak. And the test to analyze the lateral stiffness of coil spring was conducted. As a result of comparing with the test results, it was found that the results obtained by applying the lateral stiffness analysis model of Krettek and Sobczak and correcting the correction coefficient are similar to those of the test results.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.42-49
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• 2019

This paper presents a method to predict the storage reliability of springs for turbo engine components based on an accelerated degradation test. The reliability assessment procedure for springs is established to proceed with the accelerated degradation test. The spring constant is selected as the performance degradation characteristic, the temperature is determined to be the stress factor that deteriorates the spring constant. The storage tests are performed at three temperature test conditions. The spring constant is measured periodically to check the degradation status of the springs. Failure times of the springs are predicted by using the degradation model. Finally, the storage lifetime of the springs at normal use conditions is predicted using an accelerated model and failure times of all test conditions.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.559-566
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• 2012

In this study, fiber elements and a spring are used to build a reinforced concrete shear wall model. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The spring parameters representing strength and stiffness degradation, pinching, and slip were determined by comparing behaviors of fiber element and VecTor2 results. 'Pinching4' model in OpenSees is used for shear spring. The parameter selecting process for shear spring is a complicated and time consuming process. To study the applicability of the fiber element, reinforced concrete buildings containing a shear wall are evaluated using nonlinear dynamic analysis with various wall aspect ratio (H/L), various beam heights, and stiffness and flexural strength of beam and wall ratios. The aspect ratio of the wall showed distinct difference in IDR (interstory drift ratio) of the models with and without spring. On the other hand, the height of beam and ratio of stiffness and flexural strength of beam and wall did not show clear relation.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.46-51
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• 2008

The damping of a shock absorption device composed of nonlinear disk spring stacks and rubber rings was investigated. Friction forces of rubber rings and hysteresis of disk springs were obtained experimentally. The hysteresis curves of several types of disk spring stacks were approximated, from which the energy dissipated was estimated. Based upon the friction force and the energy dissipated, 4 damping models were presented and shock responses of the damping models were investigated. The hysteresis of disk spring is more meaningful than the friction of the rubber ring for the damping. For practical use, equivalent viscous damping model for total energy dissipated per cycle was suggested.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.245-253
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• 2020

In this study, natural frequencies are compared using several pile-soil interaction (PSI) models to evaluate the effects of each model on resonance safety checks for a monopile type of wind turbine structure. Base spring, distributed spring, and three-dimensional brick-shell models represented the PSIs in the finite element model. To analyze the effects of the PSI models on a natural frequency, after a stiffness matrix calculation and Winkler-based beam model for base spring and distributed spring models were presented, respectively; natural frequencies from these models were investigated for monopiles with different geometries and soil properties. These results were compared with those from the brick-shell model. The results show that differences in the first natural frequency of the monopiles from each model are small when the small diameter of monopile penetrates hard soil and rock, while the distributed spring model can over-estimate the natural frequency for large monopiles installed in weak soil. Thus, an appropriate PSI model for natural frequency analyses should be adopted by considering soil conditions and structure scale.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.68-69
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• 2011

마그네슘 판재의 온간 스프링백 거동 예측을 위한 재료 거동 모델을 고찰하였다. V-굽힘 시험에 관한 기존 문헌의 결과와 비교하여 재료 모델의 타당성을 토하였다. 스프링백 거동의 정량화를 위해 온간 S-rail 프레스금형에 의한 성형 시험을 수행하였다. 성형 시험은 다양한 온도, 속도, 성형깊이 조건에서 수행하였으며 시험 결과를 서로 비교하였다. 재료 모델을 사용하여 S-레일 성형에 따른 스프링백 예측을 위한 유한요소해석을 수행하고 그 결과를 시험 측정값과 비교하였다. 이로부터 재료 모델의 한계와 가능성을 고찰하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.297-302
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• 1998

유한요소법을 이용하여 스프링으로 연속 지지되고 축방향 하중이 작용하는 핵연료봉의 자유진동 해석올 수행하였다. 본 해석에는 지지격자 지지점에서 핵연료봉의 변위가 구속되지 않는 실제 경계조건을 반영하였다. 이러한 경계조건은 지지점 스프링 상수에 의하여 핵연료봉 해석모델의 탄성항이 약화되는 현상을 반영할 수 있어서 지지점이 구속된 기존의 모델보다 고유진동수를 작게 예측한다. 스프링 상수가 어떤 임계값 이하를 갖는 경우 고유진동수 뿐만 아니라 모드형상도 크게 변하기 때문에 지지점을 구속한 모델에 의한 해석은 실제 진동현상을 상당히 왜곡 할 수 있다. 핵연료봉에 작용하는 축방향력이 인장력에서 압축력으로 감소함에 따라 고유진동수도 감소하지만 핵연료봉의 고유형상은 변하지 않았다. 지지격자 스프링 상수의 점진적인 감소와 핵연료봉 축방향 압축력의 감소를 동시에 적용하는 경우 고유 진동수는 두 변수를 별도로 적용했을 때 얻은 최소값의 변화에 따르는 경향을 나타내었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.407-410
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• 2011

본 연구에서는 탑승객의 안전과 국내 환경에 적합한 제동거리 확보를 위해 새로운 개념의 스프링을 사용한 제동장치를 설계하고자 한다. 새로운 제동장치에 사용되는 스프링은 변위에 따라 감쇠 성능 특성을변화시키는 Multi-Rate 변위 감응형 스프링을 최적화하여 적용하였다. 이를 위한 최적화 기법으로는 비선형 최적화 기법인 순차적 2차계획법(Sequential Quadratic Programming, SQP)을 사용하였으며 먼저 Ziprider의 운동을 제동거리와 제동시 발생하는 회전각의 관계로 표현 가능한 수치모델을 개발하였다. 또한 개발된 수치모델은 Matlab을 이용하여 코드화하고 그 결과를 RecurDyn과 비교 분석하였다.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.3
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• pp.208-217
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• 2006

This paper presents a cloth simulation technique that implements plastic deformation. Plasticity is the property that material does not restore completely to the original state once deformed, in contrast to elasticity. We model cloth using a particle model, and posit two kinds of connections between particles, i.e. the sequential connections between immediate neighbors, and the interlaced connections between every other neighbors. The sequential connections represent the compression and tension of cloth, and the interlaced connections the bending in cloth. The sequential connections are modeled by elastic springs, and the interlaced connections by elastic or plastic spring depending on the amount of the current deformation of the connections. Our model is obtained by adding plastic springs to the existing elastic particle model of cloth. Using the new model, we have been able to simulate bending wrinkles, permanently deformed wrinkles, and small wrinkles widely distributed over cloth. When constructing elastic and plastic spring models for sequential and interlaced connections, we took pain to prevent the stiffness matrix of the whole cloth system from being indefinite, in order to help achieve physical stability of the cloth motion equation and to improve the effectiveness of the numerical method.