• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.191-193
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• 2016

본 논문에서는 SSD 저장장치를 포함하는 하둡의 Iterative Processing에 대한 성능 분석 결과를 소개한다. 하둡은 맵 리듀스 병렬 프로그래밍 모델을 통해 Batch Processing에 특화된 구조를 가지고 있는 프레임 워크이다. 이는 병렬/분산 환경에서 큰 성능향상을 보장하지만, 반복 작업을 수행하는 Iterative Processing에 대하여는 성능이 낮아지는 문제가 존재하고 있다. 이에 본 논문에서는 점차 낮아지는 가격으로 인해 하둡시스템에 적용 가능성이 타진되는 SSD를 통해 반복 작업의 성능이슈를 해결할 수 있는지 확인하고, SSD를 통한 성능향상의 요소가 존재하는지 알아보고자 실험을 진행하였다. 실험에서는 Batch Processing인 word count와 Iterative Processing인 Page Rank 알고리즘을 MapReduce로 구현하고 데이터 크기에 따른 성능 향상도를 측정하였고, SSD 추가와 같은 하드웨어적인 성능을 통한 하둡의 반복 작업은 큰 효율을 기대하기가 어렵다는 결론을 보였다.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.425-436
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• 2016

In this paper, a parameter optimization based iterative learning control strategy is presented for permanent magnet synchronous motor control. This paper analyzes the mechanism of iterative learning control suppressing PMSM torque ripple and discusses the impact of controller parameters on steady-state and dynamic performance of the system. Based on the analysis, an optimization problem is constructed, and the expression of the optimal controller parameter is obtained to adjust the controller parameter online. Experimental research is carried out on a 5.2kW PMSM. The results show that the parameter optimization based iterative learning control proposed in this paper achieves lower torque ripple during steady-state operation and short regulating time of dynamic response, thus satisfying the demands for both steady state and dynamic performance of the speed regulating system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.615-622
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• 2002

In this paper, the modification of double projection method for the adaptive analysis of Element-free Galerkin(EFG) method were proposed. As results of the double projection method, the smoothed error profile that is adequate for adaptive analysis was obtained by re-projection of error that means the differences of EFG stress and projected stress. However, it was found that the efficiency of double projection method is degraded as increase of the numerical integration order. Since, the iterative refinement to single step error estimation made the same effect as increasing of integration order, the application of the iterative refinement base on double projection method could be produced the inadequately refined analysis model. To overcome this defect, a modified scheme of double projection were proposed. In the numerical example, the results did not show degradation of double projection effect in iterative refinement and the efficiency of proposed scheme were proved.

• Korean Journal of Mathematics
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• v.21 no.3
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• pp.213-222
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• 2013

In this paper, we introduce and consider a new system of generalized variational inequalities involving five different operators. Using the sunny nonexpansive retraction technique we suggest and analyze some new explicit iterative methods for this system of variational inequalities. We also study the convergence analysis of the new iterative method under certain mild conditions. Our results can be viewed as a refinement and improvement of the previously known results for variational inequalities.

• YAKHAK HOEJI
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• v.48 no.1
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• pp.6-12
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• 2004

Near-infrared spectra of methanol-water mixtures and acetonitrile-water mixtures were acquired to find interactions between solvents widely used for reverse-phase liquid chromatography. Mixtures were prepared to give a series of increasing mole fractions of methanol or acetonitrile in water. Data matrices of acquired spectra were analyzed to determine the proper number of principal components of each mixture system using Malinowski's factor indicator function. Initial guess of score matrix and loading matrix were calculated by nonlinear iterative partial least squares (NIPALS) algorithm for faster computation. Iterative target transform factor analysis (ITTFA) was applied to convert the initial estimation of score matrix to true concentration profile and loading matrix to pure spectra of pure components of the mixtures. In case of methanol-water the number of principal components was found to be 4 and those initial guess of factors were converted to the pure spectra of water methanol and two kinds of complexes. In case of acetonitrile-water the number of pure components of the mixtures was found to be 3 and the pure spectrum of acetonitrile-water complex was found. The nonlinear characteristics of concentration profiles of complexes in the solvent mixtures may give a good criteria in understanding their elution characteristics in reverse-phase liquid chromatogrsphy.

• Korean Journal of Remote Sensing
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• v.33 no.5_1
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• pp.547-557
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• 2017

In this paper, a new spectral unmixing based target detection algorithm is proposed which adopted Iterative Error Analysis as a tool for extraction of background endmembers by using the target spectrum to be detected as initial endmember. In the presented method, the number of background endmembers is automatically decided during the IEA by stopping the iteration when the maximum change in abundance of the target is less than a given threshold value. The proposed algorithm does not have the dependence on the selection of image endmembers in the model-based approaches such as Orthogonal Subspace Projection and the target influence on the background statistics in the stochastic approaches such as Matched Filter. The experimental result with hyperspectral image data where various real and simulated targets are implanted shows that the proposed method is very effective for the detection of both rare and non-rare targets. It is expected that the proposed method can be effectively used for mineral detection and mapping as well as target object detection.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.5
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• pp.385-392
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• 2002

This paper introduces a new approach to analysis of error convergence for a class of iterative teaming control systems. Firstly, a nonlinear plant is represented using a Takagi-Sugeno(T-S) fuzzy model. Then each iterative learning controller is designed for each linear plant in the T-S fuzzy model. From the view point of two-dimensional(2-D) system theory, we transform the proposed learning systems to a 2-D error equation, which is also established if the form of T-S fuzzy model. We analyze the error convergence in the sense of induced L$_2$-norm, where the effects of disturbances and initial conditions on 2-D error are considered. The iterative teaming controller design problem to guarantee the error convergence can be reduced to the linear matrix inequality problem. This method provides a systematic design procedure for iterative teaming controller. A simulation example is given to illustrate the validity of the proposed method.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4350-4356
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• 2023

Radiation detection systems working at high count rates suffer from the overlapping of their output electric pulses, known as pulse pile-up phenomenon, resulting in spectrum distortion and degradation of the energy resolution. Pulse tail extrapolation is a pile-up correction method which tries to restore the shifted baseline of a piled-up pulse by extrapolating the overlapped part of its preceding pulse. This needs a mathematical model which is almost always nonlinear, fitted usually by a nonlinear least squares (NLS) technique. NLS is an iterative, potentially time-consuming method. The main idea of the present study is to replace the NLS technique by an integration-based non-iterative method (NIM) for pulse tail extrapolation by an exponential model. The idea of linear extrapolation, as another non-iterative method, is also investigated. Analysis of experimental data of a NaI(Tl) radiation detector shows that the proposed non-iterative method is able to provide a corrected spectrum quite similar with the NLS method, with a dramatically reduced computation time and complexity of the algorithm. The linear extrapolation approach suffers from a poor energy resolution and throughput rate in comparison with NIM and NLS techniques, but provides the shortest computation time.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.472-477
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• 2004

A new earthquake design method performing iterative calculations with secant stiffness was developed. Since basically the proposed design method uses linear analysis, it is convenient and stable in numerical analysis. At the same time, the proposed design method can accurately estimate the inelastic strength and ductility demands of the structural members through iterative calculations. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed method, as an integrated analysis and design method, can directly address the earthquake design strategy intended by the engineer, such as limited ductility of member and the concept of strong column - weak beam. Through iterative calculations on a structural model with member sizes preliminarily assumed, the strength and ductility demands of each member can be determined so as to satisfy the given design strategy. As the result, structural safety and economical design can be achieved.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.384-387
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• 2003

A new Direct Nonlinear Strut-Tie Model design method performing iterative calculations using secant stiffness was developed. Since basically the proposed design method uses elastic analysis, it has the advantages of convenience and stability in numerical analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it analyzes the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer, such as ductility limit on each member. Through iterative calculations on the structure preliminary designed with member sizes, the strength and ductility demands of each member can be estimated so that they satisfy the given design strategy, and as the result economical and safe design is achieved.