• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.4
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• pp.43-52
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• 1986

With increasing of computer use, a least squares method is now widely used in the regression analysis of various data. Unreliable results of regression coefficients due to the floating point of computer and problems of ordinary least squares method are described in detail. To improve these problems, a least squares method using orthogonal function is developed. Also, Comparison and analysis are performed through an example of numerical test, and re-orthogonalization method is used to increase the accuracy. As an example of application, the optimum order of AR process for the time series of monthly flow at the Pyungchang station is determined using Akaike's FPE(Final Prediction Error) which decides optimum degree of AR process. The result shows the AR(2) process is optimum to the series at the station.

• Journal of the KSME
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• v.34 no.3
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• pp.177-184
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• 1994

이 글에서는 기하공차의 기본적인 개념들에 대한 설명과 삼차원측정기 응용소프트웨어에서 기하 공차를 평가하기 위한 수학적인 방법들에 대해 소개하였다. 최소영역법은 ISO규격에 의한 공차 평가법이란 점에서 근래의 연구의 대부분을 차지하고 있으나 표준적인 알고리즘이라 할 수 있는 방법은 아직 발표되지 않고 있으며 실용적인 소프트웨어의 경우 최소자승법을 근간으로 하고 있는 실정이다. 최근에는 이러한 형상추출과 기하공차평가를 포함하는 좌표식 측정기 술(coordinate metrology)이 컴퓨터통합생산(computer integrated manufacturing)시스템 구축에 있어서 아킬레스건이라 할 수 있는 컴퓨터원용검사(computer aided quality control)의 핵심적인 기술로 인식되어 선진국에서는 이미 표준기술을 확립하고자 하는 목적으로 체계적인 지원하에 연구를 수행하고 있다. 그러므로 국내에서도 품질보증에 의한 제조업 분야의 생산성 제고를 위 하여 좌표식 측정기술에 대한 연구와 투자가 시급하며 국내의 표준기술 확립이 절실히 요청되고 있다하겠다.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.156-161
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• 2000

Least Squares and Minimum Zone method are known for obtaining a datum or a continuous approximate function of measured data. This study is for a Minimum Zone algorithm for a circle, which is useful to obtain the exact roundness from the reference circle of measured data. The proposed method is compared with the Least Squares Limacon method and Chrystal-Peirce algorithm. A computational algorithm for the Minimum Zone circle is suggested and results in less roundness than the other two methods. This Minimum Zone circle method will be used for other geometrical measured data, such as plane or sphere for obtaining the exact flatness or sphericity.

• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.178-184
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• 1993

The procedure using equivalent time at reference temperature has been assessed for the estimation of kinetic parameters with experimental data. Kinetic studies of nonenzymatic browning reaction in model and food system were carried out with linearly increasing temperature method. These kinetic parameters, n, $k_{ref}$ and $E_a$ of the systems were evaluated from original data in one step by nonlinear least square regression. The one step procedure yielded efficiently accurate parameter estimation. Computer simulated data with the kinetic models were well consistent with experimental data (average correlation coefficient=0.96).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.759-765
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• 2017

In this study, a three-dimensional least-square, level-set-based two-phase flow code was developed for the simulation of three-dimensional sloshing problems using finite element discretization. The code was validated by solving some benchmark problems. The proposed method was found to provide improved results against other existing methods, by using a coarser mesh. The results of the numerical experiments conducted during the course of this study showed that the proposed method was both robust and accurate for the simulation of three-dimensional sloshing problems. Using a substantially coarse grid, historical results of the dynamic pressure at a selected position corresponded with existing experimental data. The pressure history with a finer grid was similar to that of a coarse grid; however, a fine grid provided higher peak pressures. The present method could be extended to the analysis of a sloshing problem in a complex geometrical configuration using unstructured meshes owing to the features of FEM.

• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.129-136
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• 2005

The damped least-squares inversion has become a most popular method in finding the solution in geophysical problems. Generally, the least-squares inversion is to minimize the object function which consists of data misfits and model constraints. Although both the data misfit and the model constraint take an important part in the least-squares inversion, most of the studies are concentrated on what kind of model constraint is imposed and how to select an optimum regularization parameter. Despite that each datum is recommended to be weighted according to its uncertainty or error in the data acquisition, the uncertainty is usually not available. Thus, the data weighting matrix is inevitably regarded as the identity matrix in the inversion. We present a new inversion scheme, in which the data weighting matrix is automatically obtained from the analysis of the data resolution matrix and its spread function. This approach, named 'extended active constraint balancing (EACB)', assigns a great weighting on the datum having a high resolution and vice versa. We demonstrate that by applying EACB to a two-dimensional resistivity tomography problem, the EACB approach helps to enhance both the resolution and the stability of the inversion process.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.170-176
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• 2011

This paper analyzes the orbit determination results using azimuth and elevation angle from ground tracking data, which has the standard data interface format, GEOS-C. The ground tracking data is very useful for initial orbit determination after a satellite launch. In this paper, the quality of the measurement data has been investigated using a variety of real tracking passes, compared with the high precision orbit data of KOMPSAT-2. The accumulated tracking data from consecutive satellite-ground passes is processed for orbit determination using least square method. The accuracy of orbit determination result is also presented.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.74-82
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• 2011

To do fuzzy modelling of a nonlinear process needs to analyze the characteristics of input-output of fuzzy inference systems according to the division of entire input spaces and the fuzzy reasoning methods. For this, fuzzy model is expressed by identifying the structure and parameters of the system by means of input variables, fuzzy partition of input spaces, and consequence polynomial functions. In the premise part of the fuzzy rules Min-Max method using the minimum and maximum values of input data set and C-Means clustering algorithm forming input data into the clusters are used for identification of fuzzy model and membership functions are used as a series of triangular, gaussian-like, trapezoid-type membership functions. In the consequence part of the fuzzy rules fuzzy reasoning is conducted by two types of inferences such as simplified and linear inference. The identification of the consequence parameters, namely polynomial coefficients, of each rule are carried out by the standard least square method. And lastly, using gas furnace process which is widely used in nonlinear process we evaluate the performance and the system characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.136-142
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• 1994

This study presents an algorithm and related techniques which could satisfy the important properties of check weighers and conveyor scales. The algorithm of Recursive Least Squares Regression is described for te weighing system simulated as a dynamic model of the second order. Using the model and the algorithm, model parameters and then the mass being weighed can be determined from the step input. The performance of the algorithm is illustrated in digital simulation. Discussions are extended to the development of fast converging algorithm. It turns out that the algorithm shows several desirable features suitable for microcomputer assisted real-time signal processing, which are high precision and stability in noisy environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.129-133
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• 2019

Frequency resource efficiency is important in satellite communication systems. One of the causes of a waste of frequency resource is bad flatness. In the case, flatness of satellite Tx terminals would be worse by ACI and guard band. In order to overcome this problem, this paper proposes a technique for frequency response equalization in satellite Tx terminals. First of all, a general linear polynomial expression which meets least squares of representative measurement data is calculated to interpolate unmeasured data. And then flatness can be adjusted using the polynomial expression. Simulation results illustrate adjusted data have lower peak to peak and standard deviation than original data, and these show that flatness be improved.