• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.556-561
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• 2005

The steel shows plastic deformation after the yield point exceeds. The plastic deformation due to overloads occurs at the interior support of a continuous bridge. The plastic deformation is concentrated at the interior support and the permanence deformation at the interior support remains after loads apply. Because local yielding causes the positive moment at the interior support, it is called 'auto-moment'. Auto-moment redistributes the elastic moment. Because of redistribution, auto-moment decreases the negative moment at the interior support of a continuous bridge. In this paper, the plastic rotation is evaluated using the moment-rotation curve proposed by Schalling and Beam-line method. Moreover, auto-moment is derived from the experiment curve.

• Journal of Astronomy and Space Sciences
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• 제39권3호
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• pp.99-108
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• 2022

There are two models that explain the rotation curves of galaxies: dark matter, which gives the missing contribution to the gravitational potential of the standard theory of gravity, and modified theories of gravity, according to which the gravitational potential is created by ordinary visible mass. Both models have some disadvantages. The article offers a new look at the problem of galactic rotation curves. The author suggests that the moment of inertia creates an additional gravitational potential along with the mass. The numerical simulation carried out on the example of fourteen galaxies confirms the validity of such an assumption. This approach makes it possible to explain the constancy of gas velocities outside the galactic disk without involving the hypothesis of the existence of dark matter. At the same time, the proposed approach lacks the disadvantages of modified theories of gravity, where the gravitational potential is created only by the mass of visible matter.

• Computers and Concrete
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• 제4권6호
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• pp.457-475
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• 2007

A simple analytical procedure to analyze reinforced concrete (RC) beams with cracked section is proposed on the basis of the simplified moment-curvature relations of RC sections. Unlike previous analytical models which result in overestimation of stiffness and underestimation of structural deformations induced from assuming perfect-bond condition between steel and concrete, the proposed analytical procedure considers fixed-end rotation caused by anchorage. Furthermore, the proposed analytical procedure, compared with previous numerical models, promotes effectiveness of analysis by reflecting several factors which can influence nonlinearity of RC structure into the simplified moment-curvature relation. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed analytical procedure to the nonlinear analysis of RC structures.

• Structural Engineering and Mechanics
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• 제74권2호
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• pp.189-199
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• 2020

Researchers have elaborated several accurate methods to calculate member-end rotations or moments, directly, for bridge-type structures. Recently, the concept of rotation and moment propagation (RMP) has been presented considering bending flexibility, only. Through which, in spite of moment distribution method, all joints are free resulting in rotation and moment emit throughout the structure similar to wave motion. This paper proposes a new set of closed-form equations to calculate member-end rotation or moment, directly, comprising both shear and bending flexibility. Furthermore, the authors program the algorithm of Timoshenko beam theory cooperated with the finite element. Several numerical examples, conducted on the procedures, show that the method is superior in not only the dominant algorithm but also the preciseness of results.

• Journal of the Korean Data and Information Science Society
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• 제10권1호
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• pp.19-27
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• 1999

An orientation-shift model for unit random vectors in $R^3$ is defined. The Euler angles are introduced to parametrize orientation-shifts and their moment estimators are found. Through the analytic perturbation method, the asymptotic distributions of the estimators are obtained.

• Steel and Composite Structures
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• 제29권6호
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• pp.717-734
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• 2018

This paper presents the flexural performance of steel beam-to-column joints composed of hollow structural section beams and columns. A finite element (FE) model was developed incorporating geometrical and material nonlinearities to evaluate the behaviour of joints subjected to bending moments. The numerical outcomes were validated with experimental results and compared with EN1993-1-8. The demountability of the structure was discussed based on the tested specimen. A parametric analysis was carried out to investigate the effects of steel yield strength, end-plate thickness, beam thickness, column wall thickness, bolt diameter, number of bolts and location. Consequently, an analytical model was derived based on the component method to predict the moment-rotation relationships for the sub-assemblies with extended end-plates. The accuracy of the proposed model was calibrated by the experimental and numerical results. It is found that the FE model is fairly reliable to predict the initial stiffness and moment capacity of the joints, while EN1993-1-8 overestimates the initial stiffness extensively. The beam-to-column joints are shown to be demountable and reusable with a moment up to 53% of the ultimate moment capacity. The end-plate thickness and column wall thickness have a significant influence on the joint behaviour, and the layout of double bolt-rows in tension is recommended for joints with extended end-plates. The derived analytical model is capable of predicting the moment-rotation relationship of the structure.

• Structural Engineering and Mechanics
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• 제87권1호
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• pp.19-28
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• 2023

This paper describes the experimental investigation of steel pallet rack beam-to-column connec-tions. Total behavior of moment-rotation (M-φ) curve and the effect of particular characteristics on the behavior of connection were studied and the associated load strain relationship and corre-sponding failure modes are presented. In this respect, an estimation of SPRBCCs moment and rotation are highly recommended in early stages of design and construction. In this study, a new approach based on Support Vector Machines (SVMs) coupled with discrete wavelet transform (DWT) is designed and adapted to estimate SPRBCCs moment and rotation according to four input parameters (column thickness, depth of connector and load, beam depth,). Results of SVM-WAVELET model was compared with genetic programming (GP) and artificial neural networks (ANNs) models. Following the results, SVM-WAVELET algorithm is helpful in order to enhance the accuracy compared to GP and ANN. It was conclusively observed that application of SVM-WAVELET is especially promising as an alternative approach to estimate the SPRBCCs moment and rotation.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.131-136
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• 2001

The purpose of this paper is to develop image inspection system endows an automatic operating and measuring that the moment values are invariant with respect to variable object size and rotation. In this paper, using these moment feature vector with Hu s 7 invariant moment is also given. The characteristics of section which is applied in the mechanics used moment descriptor of invariant moment detection algorithm for image inspection system. Corresponding rates between 94% and 96% have been achived for all object tested.

• 한국융합학회논문지
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• 제11권6호
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• pp.393-400
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• 2020

본 연구는 테니스 1st 플랫서브 동작에서 어깨 통증 유무에 따른 견갑골의 움직임 차이를 확인하기 위해 테니스 선수 15명(남8, 여7)을 대상으로 3차원 영상분석시스템을 활용하여 견갑골의 앞쪽/뒤쪽 기울임, 아래쪽/위쪽 회전 및 안쪽/바깥쪽 회전에 대한 각속도와 모멘트를 산출하여 이를 집단 간 비교 분석을 하였다. 그 결과, 앞쪽/뒤쪽 기울임에 대한 최대 각속도는 실험군인 어깨통증집단(SPG)보다 대조군 집단(CG)이 빠른 경향을 보였으며, 팔로우 스로우 구간을 제외하고 모든 국면에서 안쪽/바깥쪽 회전 최대 각속도가 SPG가 CG보다 빠른 것으로 나타났다. 후기 코킹 구간에서의 앞쪽/뒤쪽 기울임 최대 모멘트가 SPG보다 CG가 더 크게 나타났고 통계적으로 유의한 차이를 보였다. 코킹 구간의 위쪽/아래쪽 회전 최대 모멘트 또한 SPG가 CG보다 작게 나타나면서 통계적으로 유의한 차이를 보였다. 안쪽/바깥쪽 회전 모멘트는 모든 국면에서 CG가 SPG보다 큰 것으로 나타났다.

• 한국강구조학회 논문집
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• 제23권4호
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• pp.405-415
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• 2011

건축물의 안전한 내진설계를 위해서는 층간변위비 뿐만 아니라 부재에 요구되는 소성변형을 평가하여야 한다. 본 연구에서는 복잡한 비선형해석 없이 탄성해석을 사용하여 강기둥-약보로 설계된 철골 특수모멘트골조의 보에 요구되는 소성변형을 평가하는 간편한 방법을 개발하였다. 개발한 방법은 탄성해석 결과를 근거로 모멘트 재분배, 기둥 단면치수 및 보 소성힌지 이동, 패널존 변형, 중력하중, 변형경화 거동 등을 고려하여 보의 소성변형각을 직접적으로 예측한다. 또한 가새골조 또는 코어벽 등 횡력 저항구조와 모멘트골조의 상호 작용인 로킹 효과 고려한다. 검증을 위하여 강기둥-약보로 설계된 6층 특수모멘트골조에 제안된 방법을 적용하여 보의 소성변형각을 예측하고, 그 결과를 비선형 해석 결과와 비교하였다. 검증 결과, 제안된 방법은 설계 변수에 따른 보의 소성변형각을 합리적으로 예측하는 것으로 나타났다.