• Honam Mathematical Journal
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• v.29 no.4
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• pp.535-542
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• 2007

In this paper, for each natural number n, we construct a polynomial $p_n$(x) of degree n so that $p_n(x)\;\leq\;p_{n+1}(x)\;\leq\;e^x$ for $x\;\geq\;-1$. These polynomials are optimal in the sense that if p(x) is a polynomial of degree n with $p_{n-l}(x)\;\leq\;p(x)\;\leq\;e^x$, then $p(x)\;\leq\;p_n(x)$.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.697-702
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• 1994

This paper illustrates a new learning control for robot manipulators using Lyapunov direct method. It has been shown that under the proposed learning control robot manipulators are always guaranteed to be asymptotically stable with respect to the number of trials. The proposed control is also robust in the sense that the exact knowledge of the nonlinear dynamics is not required except for bounding functions on the magnitude.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.302-307
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• 1989

A pressure tracking control of hydroforming process is considered in this paper. To account for nonlinearities and uncertainties of the process, an iterative learning control scheme is proposed using Cerebellar Model Arithmatic Computer (CMAC). The experimental result shows that the proposed learning control is superior to any fixed gain controller in the sense that it enables the system to do the same work more effectively as the number of operation increases.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.554-559
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• 1986

This paper considers the problem of stabilizing a composite system formed by interconnecting a number of single-input single-output linear continuous systems. The problem is general in the sense that in addition to the standard assumption about the uncertainty of the subsystems, the strength of interconnections is assumed unknown. A method to design a local adaptive feedback control is first presented, and then the resultant closed-loop system is assured to be globally stable. Also, a numerical example is illustrated via computer simulation.

• Journal of the Korean Statistical Society
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• v.35 no.3
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• pp.251-260
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• 2006

The proportional hazards model (PHM) can be associated with a non- homogeneous Markov chain (NHMC) in the sense that sample alignments in the PHM correspond to trajectories of the NHMC. As a result the partial likelihood widely used for the PHM is a probabilistic function of the trajectories of the NHMC. In this paper, we show that, as the total number of subjects involved increases, the trajectories of the NHMC, i.e. sample alignments in the PHM, converges to the solution of an ordinary differential equation which, subsequently, characterizes the almost sure limit of the partial likelihood.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2448-2454
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• 2008

Urban areas face congestion problems that diminish personal mobility and freight-transportation productivity. An increasing number of experts suggest that separating freight traffic from passenger traffic makes sense in terms of economics, the environment, and safety. Some experts suggest that underground freight transportation are the solution. The objective of this paper is to review the potential benefits and limitations of freight pipelines as a viable mode of cargo transport that can alleviate congestion on urban highways.

• The Mathematical Education
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• v.39 no.1
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• pp.49-58
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• 2000

The purpose of this study is to investigate how to teach algorithms in mathematics class. Until recently, traditional school mathematics was primarily treated as drill and practice or memorizing of algorithmic skills. In an attempt to shift the focus and energies of mathematics teachers toward problem solving, conceptual understanding and the development of number sense, the recent reform recommendations do-emphasize algorithmic skills, in particular, paper-pencil algorithms. But the development of algorithmic thinking provides the foundation for student's mathematical power and confidence in their ability to do mathematics. Hence, for learning algorithms meaningfully, they should be taught with problem solving and conceptual understanding.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.40.4-40
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• 2001

This paper addresses the problem of designing robust adaptive output tracking control for a class of MIMO nonlinear systems which have different number of inputs and outputs The stability of the whole closed-loop system is guaranteed in the sense of Lyapunov and uniformly Itimately boundedness of the tracking error vector as well as estimated parameters are shown. In addition, we show that the restrictive assumptions on input gain matrix which is presumed in the past works can be eliminated by using proposed control law.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.90-102
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• 2017

Recently, the number of out-of-school adolescents has been increasing, and problems associated with their careers have become an important issue. This study was conducted to identify the relationship between the career barriers and perceived social support type/support source and to examine whether a sense of alienation mediates the relationship between perceived social support and career barriers among out-of-school adolescents preparing for the qualification examination for their high school degree. To accomplish this, a survey of 207 students from the Youth Support Center for out-of-school adolescents-K-Dream-and Qualification Examination Institute located in five regions (Seoul, Busan, Jeju, Gangwon, and Jeonla province) was conducted. Correlation analysis, regression analysis and the Sobel test were used to verify the relationships between variables and mediation effects. The results showed a significant negative correlation between social support and career barriers and a significant positive correlation between alienation and career barriers. Carrier barriers and alienation were highly correlated with parent support and evaluation support. Moreover, a sense of alienation was found to fully mediate the relationship between parental support/teacher support and career barriers, as well as to partially mediate the relationship between peer support and career barriers. A sense of alienation was found to fully mediate the relationship between information support/evaluation support/emotional support/material support and career barriers. These findings imply that, in out-of-school adolescents, career barriers can be reduced through various kinds of social support provided by peers, parents and teachers as it decreases the sense of alienation.

• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.245-250
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• 2011

Parallel imaging technique can provide several advantages for a multitude of MRI applications. Especially, in SENSE technique, sensitivity maps were always required in order to determine the reconstruction matrix, therefore, a number of difference approaches using sensitivity information from coils have been demonstrated to improve of image quality. Moreover, many filtering methods were proposed such as adaptive matched filter and nonlinear diffusion technique to optimize the suppression of background noise and to improve of image quality. In this study, we performed SENSE reconstruction using computer simulations to confirm the most suitable method for the feasibility of filtering effect and according to changing order of polynomial fit that were applied on variation of spatial resolution of sensitivity map. The image was obtained at 0.32T(Magfinder II, Genpia, Korea) MRI system using spin-echo pulse sequence(TR/TE = 500/20 ms, FOV = 300 mm, matrix = $128{\times}128$, thickness = 8 mm). For the simulation, obtained image was multiplied with four linear-array coil sensitivities which were formed of 2D-gaussian distribution and the image was complex white gaussian noise was added. Image processing was separated to apply two methods which were polynomial fitting and filtering according to spatial resolution of sensitivity map and each coil image was subsampled corresponding to reduction factor(r-factor) of 2 and 4. The results were compared to mean value of geomety factor(g-factor) and artifact power(AP) according to r-factor 2 and 4. Our results were represented while changing of spatial resolution of sensitivity map and r-factor, polynomial fit methods were represented the better results compared with general filtering methods. Although our result had limitation of computer simulation study instead of applying to experiment and coil geometric array such as linear, our method may be useful for determination of optimal sensitivity map in a linear coil array.