• Title/Summary/Keyword: approximate values

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Development of an Automatic Design Program for the Aspherical Lens by using the Ray Tracing Method (광선추적방식을 적용한 비구면렌즈 자동설계 프로그램 개발)

  • Kim S.Y.;Kim T.H.;Jang S.G.;Park J.W.;Jeon E.C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.494-498
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    • 2005
  • In order to design the aspherical lens, the revisions and the steps of the mathematical method are influenced with a lot of variables. The accuracy of the aspherical lens can be changed by these variables. Besides, to design the aspherical lens, many mathematical functions should be used. To use these mathematical functions is protected by patent administration. Therefore it is very difficult for most of developed countries to use them. This fact has been interrupting not only the development of the technique of a design of the aspherical lens but also the development of the equipments of optics. Because approximate values are used in most of common programs which create the aspherical lens : basically these common programs have variations. Therefore these aspherical lens are not accurate. In the paper, we calculated accurate values by using the refractive index of lens. Based on these data, wee created self-operating design programs. Consequently, our lens is more accurate than the aspherical lens which is created by the common programs influenced with approximate values. The used programs belonging to AutoCAD is Visual LISP.

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Inhomogeneities in Korean Climate Data (II): Due to the Change of the Computing Procedure of Daily Mean (기상청 기후자료의 균질성 문제 (II): 통계지침의 변경)

  • Ryoo, Sang-Boom;Kim, Yeon-Hee
    • Atmosphere
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    • v.17 no.1
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    • pp.17-26
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    • 2007
  • The station relocations, the replacement of instruments, and the change of a procedure for calculating derived climatic quantities from observations are well-known nonclimatic factors that seriously contaminate the worthwhile results in climate study. Prior to embarking on the climatological analysis, therefore, the quality and homogeneity of the utilized data sets should be properly evaluated with metadata. According to the metadata of the Korea Meteorological Administration (KMA), there have been plenty of changes in the procedure computing the daily mean values of temperature, humidity, etc, since 1904. For routine climatological work, it is customary to compute approximate daily mean values for individual days from values observed at fixed hours. In the KMA, fixed hours were totally 5 times changed: at four-hourly, four-hourly interval with additional 12 hour, eight-hourly, six-hourly, three-hourly intervals. In this paper, the homogeneity in the daily mean temperature dataset of the KMA was assessed with the consistency and efficiency of point estimators. We used the daily mean calculated from the 24 hourly readings as a potential true value. Approximate daily means computed from temperatures observed at different fixed hours have statistically different properties. So this inhomogeneity in KMA climate data should be kept in mind if you want to analysis secular aspects of Korea climate using this data set.

On Information Criteria in Linear Regression Model

  • Park, Man-Sik
    • The Korean Journal of Applied Statistics
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    • v.22 no.1
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    • pp.197-204
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    • 2009
  • In the model selection problem, the main objective is to choose the true model from a manageable set of candidate models. An information criterion gauges the validity of a statistical model and judges the balance between goodness-of-fit and parsimony; "how well observed values ran approximate to the true values" and "how much information can be explained by the lower dimensional model" In this study, we introduce some information criteria modified from the Akaike Information Criterion (AIC) and the Bayesian Information Criterion(BIC). The information criteria considered in this study are compared via simulation studies and real application.

Estimation of Power Generation Capacity from Agricultural Biomass (농업부산물 부존량 조사 및 발전 가능량의 추정)

  • Hong, Seong-Gu
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2003.10a
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    • pp.595-598
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    • 2003
  • Elemental data was collected for agricultural biomass such as pruned branches with respect to unit area production and heating values. The results indicated that higher heating values for the biomass was comparable to those of woody biomass. Approximate estimations of power generation from biomass showed that over 100kW power plants could be installed in some districts.

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Estimation based on lower record values from exponentiated Pareto distribution

  • Yoon, Sanggyeong;Cho, Youngseuk;Lee, Kyeongjun
    • Journal of the Korean Data and Information Science Society
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    • v.28 no.5
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    • pp.1205-1215
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    • 2017
  • In this paper, we aim to estimate two scale-parameters of exponentiated Pareto distribution (EPD) based on lower record values. Record values arise naturally in many real life applications involving data relating to weather, sport, economics and life testing studies. We calculate the Bayesian estimators for the two parameters of EPD based on lower record values. The Bayes estimators of two parameters for the EPD with lower record values under the squared error loss (SEL), linex loss (LL) and entropy loss (EL) functions are provided. Lindley's approximate method is used to compute these estimators. We compare the Bayesian estimators in the sense of the bias and root mean squared estimates (RMSE).

Sequential Approximate Optimization by Dual Method Based on Two-Point Diagonal Quadratic Approximation (이점 대각 이차 근사화 기법을 쌍대기법에 적용한 순차적 근사 최적설계)

  • Park, Seon-Ho;Jung, Sang-Jin;Jeong, Seung-Hyun;Choi, Dong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.3
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    • pp.259-266
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    • 2011
  • We present a new dual sequential approximate optimization (SAO) algorithm called SD-TDQAO (sequential dual two-point diagonal quadratic approximate optimization). This algorithm solves engineering optimization problems with a nonlinear objective and nonlinear inequality constraints. The two-point diagonal quadratic approximation (TDQA) was originally non-convex and inseparable quadratic approximation in the primal design variable space. To use the dual method, SD-TDQAO uses diagonal quadratic explicit separable approximation; this can easily ensure convexity and separability. An important feature is that the second-derivative terms of the quadratic approximation are approximated by TDQA, which uses only information on the function and the derivative values at two consecutive iteration points. The algorithm will be illustrated using mathematical and topological test problems, and its performance will be compared with that of the MMA algorithm.

A Study on the Effective Free Surface of Fluid Cargo (유동화물의 유효자유표면에 관한 연구)

  • Hur, I.;Wang, J.S.
    • Journal of the Korean Institute of Navigation
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    • v.11 no.2
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    • pp.73-88
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    • 1987
  • It is well known that the height of tank metacenter above the centroid of fluid in a tank is given by i/v where I is the inertia moment of free surface and v is the fluid volume. It is supposed in this formula that the inclination of ship is small and that the free surface of fluid do not touch the top and the bottom of tank. It the inclination of ship is large, the height of tank metacenter may be possibly greater than that given by i/v. The height of tank metacenter is smaller than i/v when the free surface of fluid touch the top or the bottom of tank. The reasonable method to calculate the height of tank metacenter is presented in this paper and prepared in FORTRAN program by FUNCTION EFFRES. The approximate formula was also developed and given by $g_m=(1+\frac{2}{1}tan^2\theta)[1-EXP\{-12(\frac{\alpha(1-\alpha)k}{tan\theta})^{1.25}\}]\frac{i}{v}$ where $g_m$ is the distance from the centroid of fluid to the tank metacenter, $\theta$ is inclined angle of ship, $\alpha$ is the ratio of filled volume to tank capacity and k is the ratio of the depth to the width of tank. The values calculated by the approximate formula given in this paper were compared with the exact values from the computer program and proved out to be sufficiently precise for practical use.

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Response prediction of laced steel-concrete composite beams using machine learning algorithms

  • Thirumalaiselvi, A.;Verma, Mohit;Anandavalli, N.;Rajasankar, J.
    • Structural Engineering and Mechanics
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    • v.66 no.3
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    • pp.399-409
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    • 2018
  • This paper demonstrates the potential application of machine learning algorithms for approximate prediction of the load and deflection capacities of the novel type of Laced Steel Concrete-Composite (LSCC) beams proposed by Anandavalli et al. (Engineering Structures 2012). Initially, global and local responses measured on LSCC beam specimen in an experiment are used to validate nonlinear FE model of the LSCC beams. The data for the machine learning algorithms is then generated using validated FE model for a range of values of the identified sensitive parameters. The performance of four well-known machine learning algorithms, viz., Support Vector Regression (SVR), Minimax Probability Machine Regression (MPMR), Relevance Vector Machine (RVM) and Multigene Genetic Programing (MGGP) for the approximate estimation of the load and deflection capacities are compared in terms of well-defined error indices. Through relative comparison of the estimated values, it is demonstrated that the algorithms explored in the present study provide a good alternative to expensive experimental testing and sophisticated numerical simulation of the response of LSCC beams. The load carrying and displacement capacity of the LSCC was predicted well by MGGP and MPMR, respectively.

Approximate methods to evaluate storey stiffness and interstory drift of RC buildings in seismic area

  • Caterino, N.;Cosenza, E.;Azmoodeh, B.M.
    • Structural Engineering and Mechanics
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    • v.46 no.2
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    • pp.245-267
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    • 2013
  • During preliminary design of a RC building located in a seismic area, having quick but reliable analytical measurement of interstory drifts and storey stiffnesses might be helpful in order to check the fulfillment of damage limit state and stiffness regularity in elevation required by seismic design codes. This paper presents two approximate methods, strongly interrelated each other, and addressed to achieve each of these two purposes for frame buildings. A brief description of some already existing methods addressed to the same aims is included to compare the main differences in terms of general approaches and assumptions. Both new approximate methods are then applied to 9 'ideal' frames and 2 'real' buildings designed according to the Italian seismic code. The results are compared with the 'exact' values obtained by the code-based standard calculation, performed via FEM models, showing a satisfactory range of accuracy. Compared with those by the other methods from literature, they indicate the proposed procedures lead to a better approximation of the objective structural parameters, especially for those buildings designed according to the modern 'capacity design' philosophy.