• 경영과학
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• 제15권1호
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• pp.49-62
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• 1998

The purpose of this paper is to develope a large-scale simplex method program LPAKO. Various up-to-date techniques are argued and implemented. In LPAKO, basis matrices are stored in a LU factorized form, and Reid's method is used to update LU maintaining high sparsity and numerical stability, and further Markowitz's ordering is used in factorizing a basis matrix into a sparse LU form. As the data structures of basis matrix, Gustavson's data structure and row-column linked list structure are considered. The various criteria for reinversion are also discussed. The dynamic steepest-edge simplex algorithm is used for selection of an entering variable, and a new variation of the MINOS' perturbation technique is suggested for the resolution of degeneracy. Many preprocessing and scaling techniques are implemented. In addition, a new, effective initial basis construction method are suggested, and the criteria for optimality and infeasibility are suggested respectively. Finally, LPAKO is compared with MINOS by test results.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.42-50
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• 2013

The reactionary responses to control human standing dynamics were estimated under the assumption that postural complexity mainly occurs in the mid-sagittal plane. During the experiment, the subject was exposed to continuous horizontal perturbation. The ankle and hip joint rotations of the subject mainly contributed to maintaining standing postural control. The designed mobile platform generated anterior/posterior (AP) motion. Non-predictive random translation was used as input for the system. The mean acceleration generated by the platform was measured as $0.44m/s^2$. The measured data were analyzed in the frequency domain by the coherence function and the frequency response function to estimate its dynamic responses. The significant correlation found between the input and output of the postural control system. The frequency response function revealed prominent resonant peaks within its frequency spectrum and magnitude. Subjects behaved as a non-rigid two link inverted pendulum. The analyzed data are consistent with the outcome hypothesized for this study.

• Journal of the Korean Data and Information Science Society
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• 제7권2호
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• pp.257-262
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• 1996

본 논문은 스플라인 희귀모형에서 평활모수를 추정할 때 사전 작업으로 영향력 진단을 하는 문제를 다룬다. 평활모수의 추정방법으로 일반화최대우도함수법을 사용할 때, 얻어지는 추정 치에 영향을 주는 관측치를 진단하는 측도를 제안하고, 찾아낸 영향력 관측치를 수정하여 올바른 평활모수 추정치를 찾는 방법을 소개한다.

• 에너지공학
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• 제23권4호
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• pp.215-222
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• 2014

A theory-based methodology for describing the thermodynamic properties of molecular nitrogen is presented. The results obtained indicate a successful application of a fully consistent statistical method for the description of a molecular system in different phase states. The method employs a density of states equation for solid nitrogen and a perturbation potential for gaseous and liquid nitrogen. The main characteristics of the calculation method include the need for a minimal number of initial data and the absence of fitting parameters. The adequacy of the physical model that is the basis for the method allows a description of existing experimental data and the peculiarities of the thermodynamic properties.

• 한국경영과학회지
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• 제29권1호
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• pp.43-56
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• 2004

The purpose of clustering is to partition a set of objects into several clusters based on some appropriate similarity measure. In most cases, clustering is considered without any prior information on the number of clusters or the structure of the given data, which makes clustering is one example of very complicated combinatorial optimization problems. In this paper we propose a general-purpose clustering method that can determine the proper number of clusters as well as efficiently carry out clustering analysis for various types of data. The method is composed of two stages. In the first stage, two different hierarchical clustering methods are used to get a reasonably good clustering result, which is improved In the second stage by ASA(accelerated simulated annealing) algorithm equipped with specially designed perturbation schemes. Extensive experimental results are given to demonstrate the apparent usefulness of our ASA clustering method.

• Journal of the Korean Statistical Society
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• 제26권2호
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• pp.277-288
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• 1997

For the analysis of survival data including covariates whose effects vary in time, the multiprocess discount survival model is proposed. The parameter vector modeling the time-varying effects of covariates is to vary between time intervals and its evolution between time intervals depends on the perturbation of the next time interval. The recursive estimation of the parameter vector can be obtained at the end of each time interval. The retrospective estimation of the survival function and the forecasting of the survival function of individuals of the specific covariates also can be obtained based on the information gathered until the end of the time interval.

• 천문학회보
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• 제36권2호
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• pp.51.2-51.2
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• 2011

We have studied the topology of volume-limited galaxy sample selected from the very luminous red galaxies (LRGs) in the completed Sloan Digital Sky Survey. LRGs are predominantly massive elliptical galaxies and tend to reside in massive dark matter halos. We compared the observed genus statistics with predictions from perturbation theory and mock LRG surveys constructed from dark matter halos in a Lambda CDM model. To compare with the observational data, we made 129 mock surveys in the past light cone space by using three different size CDM simulations: 41203 particle 6592 Mpc/h, 60003 particle 7200 Mpc/h, and $7210^3$ particle 10815 Mpc/h.

• 대한전자공학회논문지
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• 제17권5호
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• pp.1-7
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• 1980

본 논문에서는 스트라입구조형 DH Laser Diode에서의 lateral guiding에 대한 이론적 해석이 시도되었다. 해석과정에서 활성층내의 반송자밀도를 스트라입폭함수로 모멜링하고 섭동이론(Perturbation Theory)을 사용하여 새로이 전개된 모드이론으로부터 빔폭변화를 계산하여 Hakki의 이론치 및 Kirkby의 실험치와 비교분석을 하였다.

• Transactions on Electrical and Electronic Materials
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• 제17권1호
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• pp.29-32
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• 2016

Using the various exchange-correlation functionals, such as LDA, GGA-PBE, GGA-PBEsol and GGA-AM05 functionals, first principle studies were conducted to determine the structures of paraelectric and ferroelectric PbTiO₃. Based on the structures determined by the various functionals, the piezoelectric properties of PbTiO₃ are predicted under the density-functional perturbation theory (DFPT). The present prediction with the various GGA functionals are closer to the experimental findings compared to the LDA values. The present DFT calculations using the GGA-PBEsol functional estimate the experimental data more reasonably than the conventional LDA and GGA fucntionals. The GGA-AM05 functional also predicts the experimental data as well as the GGA-PBEsol. The piezoelectric tensor calculated with PBEsol is relatively insensitive to pressure.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.877-882
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• 2001

The solvent effects on the relative free energies of Eu3+ to Yb3+ ion mutation in solution have been investigated using a Monte Carlo simulation of statistical perturbation theory (SPT). Our results agree well with available data that were obtained by others. Particularly, the results of water (SPC/E) solvent are almost identical with experimental data. For the present Eu3+ and Yb3+ ions, the relative free energies of solvation vs. Born’s function of bulk solvents decrease with increasing Born’s function of bulk solvents. There is also good agreement between the calculated structural properties in this study and the published works obtained by computer simulation and experimental work.