• Title/Summary/Keyword: moment of method

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Prediction of Organic Acid Chromatogram in High Performance Ion Chromatography (고성능 이온 크로마토그래피에서 유기산의 크로마토그램 예측 연구)

  • 원혜진;한선호;박양순;조기수;김인호
    • KSBB Journal
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    • v.15 no.1
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    • pp.60-65
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    • 2000
  • In order to predict the chromatogram for organic acid in ion chromatography, Langmuir isotherm parameters were obtained by Retention Time Method (RTM) and moment method. Ion chromatography analysis for formic acid was performed and compared with theoretically predicted profiles under isocratic condition. Band profiles were estimated with the equilibrium-dispersive model of chromatography using a PDEsolver Macsyma . The relationship between the characteristics of chromatogram and the variable operating condition in chromatography such as the flow rate, ionic strength and injection volume was studied. Satisfactory agreement was observed between the experimental and the estimated chromatograms with parameters obtained form the moment method.

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Performance Improvement of a Moment Method for Reliability Analysis Using Kriging Metamodels (크리깅 근사모델을 이용한 통계모멘트 기반 신뢰도 계산의 성능 개선)

  • Ju Byeong-Hyeon;Cho Tae-Min;Jung Do-Hyun;Lee Byung-Chai
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.8 s.251
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    • pp.985-992
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    • 2006
  • Many methods for reliability analysis have been studied and one of them, a moment method, has the advantage that it doesn't require sensitivities of performance functions. The moment method for reliability analysis requires the first four moments of a performance function and then Pearson system is used for the probability of failure where the accuracy of the probability of failure greatly depends on that of the first four moments. But it is generally impossible to assess them analytically for multidimensional functions, and numerical integration is mainly used to estimate the moment. However, numerical integration requires many function evaluations and in case of involving finite element analyses, the calculation of the first fo 따 moments is very time-consuming. To solve the problem, this research proposes a new method of approximating the first four moments based on kriging metamodel. The proposed method substitutes the kriging metamodel for the performance function and can also evaluate the accuracy of the calculated moments adjusting the approximation range. Numerical examples show the proposed method can approximate the moments accurately with the less function evaluations and evaluate the accuracy of the calculated moments.

Seismic Performance Evaluation According to Rotation Capacity of Connections for Intermediate Steel Moment Frames - I. Performance Evaluation (접합부 회전성능에 따른 중간 철골 모멘트 골조의 내진 성능 평가 - I 성능평가)

  • Moon, Ki Hoon;Han, Sang Whan;Ha, Seung Jin
    • Journal of the Earthquake Engineering Society of Korea
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    • v.18 no.2
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    • pp.95-103
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    • 2014
  • The current AISC341-10 standard specifiesa value of 0.02 radian for the minimum rotation capacity of connections for the intermediate steel moment frame system. However, despite of the advances realized in the domains of performance evaluation method and analysis method, research onthe minimum rotation capacity of the intermediate steel moment frame systemsatisfying the seismic performance has not been conducted in detail. In this study, the intermediate moment frame systemisdesigned with respect to current standards and the seismic performance in accordance with the rotational capacity of connections is evaluated using the seismic performance evaluation method presented in FEMA-P695. The minimum rotation capacity of intermediate steel moment frames required to satisfy seismic performance as well as the major design values affecting the seismic performance of moment frame areestimated. To that goal, the design parameters are selected and various target frames are designed. The analysis models of the main nonlinear elements are also developed for evaluating seismic performance. The resultsshow that the 20-story structure doesnot meet the seismic performance even if it satisfies the rotation capacity of 0.02 radian.

Calculation of characteristic Impedance of the U-Type Transmission Line by the Moment Method (모먼트법에 의한 U형 부송선의 특성임피던스 계산)

  • 이상설
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.19 no.1
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    • pp.29-34
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    • 1982
  • We can find the characteristic impedances of the U-type transmission lines by finite d ifference method. In this paper, the characteristic impedances of the lines are computed by the moment method. There are 10% differences between the results of the finite difference method and those of the moment method. But when the interior conductor of the line is located at the center of the exterior conductor, the results of the moment method approache to that of analytical result when the length of outer conductor becomes in finite.

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Creep analysis of concrete filled steel tube arch bridges

  • Wang, Y.F.;Han, B.;Du, J.S.;Liu, K.W.
    • Structural Engineering and Mechanics
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    • v.27 no.6
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    • pp.639-650
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    • 2007
  • Applying the method calculating creep of Concrete Filled steel Tube (CFT) members based on the Elastic Continuation and Plastic Flow theory for concrete creep with the finite element method, the paper develops a new numerical method for the creep of CFT arch bridges considering effects of bending moment. It is shown that the method is feasible and reasonable through comparing the predicted stresses and deflection caused by the creep with the results obtained by the method of Gu et al. (2001) based on ACI209R model and experimental data of an actual CFT arch bridge. Furthermore, nine CFT arch bridges with different types are calculated and analyzed with and without the effects of bending moment. As a result, the bending moment has considerable influences on long-term deformations and internal forces of CFT arch bridges, especially when the section of arch rib is subjected to a large bending moment.

Moment Redistribution for Moment-Resisting Frames using Secant Stiffness Analysis Method (할선강성해석법을 이용한 모멘트저항골조의 모멘트 재분배)

  • Park, Hong-Gun;Kim, Chang-Soo;Eom, Tae-Sung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.221-224
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    • 2008
  • A secant stiffness linear analysis method was developed for moment redistribution of moment-resisting frames. In the proposed method, rotational spring models are used for plastic hinges of the members whose flexural moments are needed to be redistributed. At the plastic hinges, secant stiffness is used to address the effect of the flexural stiffness reduced by inelastic deformation. Linear analysis is repeated with adjusted secant stiffness until the flexural equilibrium is satisfied in the structure and members. By using the secant stiffness analysis, the effect of the inelastic deformation on the moment redistribution can be considered. Further, the safety of plastic hinges can be evaluated by comparing the inelastic rotation resulting from the secant stiffness analysis with the rotational capacity of the plastic hinges. For verification, the proposed method was applied to a continuous beam tested in previous study. A application example for a multiple story moment-resisting frame was presented.

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Inertia Identification Algorithm Using Speed Observer (속도관측기를 이용한 관성 추정 알고리즘)

  • Choi, Jong-Woo;Lee, Kwang-Soo;Kim, Heung-Geun
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.542-545
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    • 2005
  • This paper proposes an algorithm for the moment of inertia estimation. The algorithm finds the moment of inertia observing the position error signal, which contains an error information of moment of inertia, generated by speed observer. Moreover, the proposed algorithm is easily realized in the observer -based speed detection method. The experimental results are also presented to confirm the performance of moment of inertia estimation method. The results show that the moment of inertia converges to the actual value with the proposed method.

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Estimation of Knee Muscle Length and Moment Arm Using Knee Joint Angle (무릎 관절각을 이용한 무릎 근육 길이와 모멘트 암 추정)

  • Lee, Jae-Kang;Nam, Yoon-Su
    • Journal of Industrial Technology
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    • v.28 no.A
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    • pp.167-176
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    • 2008
  • Recently, lots of studies are performed in developing of active orthosis. Exact and simple muscle force estimation is important in developing orthosis which assists muscle force for disabled people or physical laborers. Hill-type muscle model dynamics is common method for estimation of muscle forces. In Hill-type muscle model, we must know muscle length and moment arm which largely affect muscle force. And several methods are proposed to estimate muscle length and moment arm using joint angle. In this study, we compared estimation results of those method with data from body model of opensim to find which method is exact for estimation of muscle length and moment arm.

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Improving Efficiency of the Moment Estimator of the Extreme Value Index

  • Yun, Seokhoon
    • Journal of the Korean Statistical Society
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    • v.30 no.3
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    • pp.419-433
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    • 2001
  • In this paper we introduce a method of improving efficiency of the moment estimator of Dekkers, Einmahl and de Haan(1989) for the extreme value index $\beta$. a new estimator of $\beta$ is proposed by adding the third moment ot the original moment estimator which is composed of the first two moments of the log-transformed sample data. We establish asymptotic normality of the new estimator and examine and adaptive procedure for the new estimator. The resulting adaptive estimator proves to be asymptotically better than the moment estimator particularly for $\beta$<0.

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Design of 3-component Force/Moment Sensor with Force/Moment Ratio of Wide Range (넓은 범위의 힘/모멘트비를 갖는 3분력 힘/모멘트 센서 설계)

  • Kim, Gap-Sun
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.2
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    • pp.214-221
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    • 2001
  • This paper describes the design of 3-component force/moment sensor with the force and moment ratio of wide range. It can measure the x-direction force Fx, y-direction force Fy and z-direction moment Mz simultaneously. In order to accurately measure forces and moment using 3-component force/moment sensor, it should get suitable force and moment ratio(the ratio of force Fx=200 N and moment Mz=20 Nm is ten to one), and small interference error. In this paper, in order to design the 3-component force/moment sensor with the force and moment ratio of wide range, the procedures are performed as follow : 1) the derivation of the equations to predict the bending strains on the surfaces of the plate-beams under the force or the moments, 2) the determination of the size of the sensing elements of the force/moment sensor by using the derived equations, 3) the Finite Element Method(FEM) analysis and the characteristic test for confirming the strains from the theory analysis, 4) the selection of the attachment locations of the strain gages of each sensor, 5) the analysis of the rated strain and the interference error at the attachment location of strain gages. It reveals that the rated strains calculated from the derived equations make a good agreement with the results from the Finite Element Method analysis and the characteristic test.

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