• The Transactions of the Korean Institute of Power Electronics
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• 제6권2호
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• pp.115-124
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• 2001

In this paper, authors propose a new nonlinear rotor flux observer for rotor field oriented control of an induction motor which is designed based on the extended Luenberger Observer theory. Extended Luenberger Observer requires minimal solution of nonlinear partial differential equation on its coordinate transformation and linearization needed on a nonlinear observer design in general. The proposed rotor flux observer is derived from the 2 phase model of induction motor on the orthogonal coordination and it has the reduce gain matrix. Simulation and experimentation were performed under the conventional indirect vector control and direct vector control with the proposed observer at different rotor resistance. Simulation results show that the convergence of the proposed observer is influenced by the chosen eigenvalues. Experimentation results on load operation show the direct vector control with the proposed observer is better than the indirect vector control to maintain the characteristics of the vector control.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제17권2호
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• pp.129-136
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• 2016

This was a methodological study that verified the validity and reliability by translating and modifying the Korean Version of LRM (leader rapport management) tool. This study verified the content validity, construct validity, concurrent validity and convergent validity on 200 nurses working in general hospitals. The LRM tool was analyzed using a total of 3 factors (ego, autonomy, association) and 12 items. The reliability of this tool (Cronbach's ${\alpha}$) was 0.83 to 0.86. The tool showed a high level of reliability and validity. The difference from preceding studies showed that the LRM is a measurement tool that considers multi-dimensional aspects, and it can provide the basic material of report management methods in diverse aspects for clinical nurse managers.

• Journal of the Korean Institute of Intelligent Systems
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• 제15권7호
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• pp.893-898
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• 2005

Due to the merits that only a small amount of computation is needed for solutions and stochastic policies can be handled explicitly, the actor-critic algorithm, which is a class of reinforcement learning methods, has recently attracted a lot of interests in the area of artificial intelligence. The actor-critic network composes of tile actor network for selecting control inputs and the critic network for estimating value functions, and in its training stage, the actor and critic networks take the strategy, of changing their parameters adaptively in order to select excellent control inputs and yield accurate approximation for value functions as fast as possible. In this paper, we consider a new actor-critic algorithm employing an RLS(Recursive Least Square) method for critic learning, and policy gradients for actor learning. The applicability of the considered algorithm is illustrated with experiments on the two linked robot arm.

• Journal of the Korea institute for structural maintenance and inspection
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• 제16권5호
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• pp.29-39
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• 2012

The main objective is to predict the future degradation and maintenance budget for a suspension bridge system. Bayesian inference is applied to find the posterior probability density function of the source parameters (damage indices and serviceability), given ten years of maintenance data. The posterior distribution of the parameters is sampled using a Markov chain Monte Carlo method. The simulated risk prediction for decreased serviceability conditions are posterior distributions based on prior distribution and likelihood of data updated from annual maintenance tasks. Compared with conventional linear prediction model, the proposed quadratic model provides highly improved convergence and closeness to measured data in terms of serviceability, risky factors, and maintenance budget for bridge components, which allows forecasting a future performance and financial management of complex infrastructures based on the proposed quadratic stochastic regression model.

• Journal for History of Mathematics
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• 제21권4호
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• pp.79-86
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• 2008

The sex ratio at birth of South Korea is exceeding the natural sex ratio at birth, which is estimated to be about 105. One of the reasons of high sex ratio at birth is due to sex-selective abortion which is caused by strong son preference. The main objective of this study is to identify whether the families which are trying to bear children only until they acquire one son contribute to high sex ratio at birth. As a result, we obtain the theorem that if the number of such families diverge, the sex ratio at birth converges to the natural sex ratio almost surely. Therefore, we conclude that the existence of the families which are trying to bear children only until they receive one son does not affect the sex ratio at birth.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제20권4호
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• pp.501-507
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• 2007

In the first part of this study, the moving least squares finite difference method for solving solid mechanics problems was formulated. This second part verified the accuracy, robustness and effectiveness of the developed method through several numerical examples. It was shown that the method gives excellent convergence rate for elasticity problem. The solution process of elastic crack problems showed the easiness in discontinuity modeling and demonstrates the accuracy and efficiency in finding singular stress solution based on adaptive node distribution. The applicability to the engineering problem with abrupt change in displacement and stresses gradient fields is verified through a localization band problem. The developed method is expected to be extended to the various special engineering problems.

• Journal of the Korea Society of Computer and Information
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• 제11권2호
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• pp.93-99
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• 2006

Ontology is an indispensable component in intelligent and semantic processing of knowledge and information, such as in semantic web. Ontology is considered to be constructed generally on the basis of taxonomy of human concepts about the world. However. as human concepts are unstructured and obscure, ontology construction based on the taxonomy of human concepts cannot be realized systematically furthermore automatically. So, we try to do this from the relation among linguistic symbols regarded representing human concepts, in short, words. We show the similarity between taxonomy of human concepts and relation among words. And we propose a methodology to construct and generate automatically ontologies from these relations mon words and a series of algorithm to convert these relations into ontologies. This paper presents the process and concrete application of this methodology.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제11권7호
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• pp.2436-2443
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• 2010

The present study aims at investigating conflict-raising factors generable for or during a familial travel in our country, with an outlook that understanding of such conflict raisers in an analytic manner be utilized as the basic data for research on travel behaviors. More specifically, key focus in this study was made on the aspect of tourism science, to wit, how sort of conflict inducers existent between a decision maker of a family and its constituents during outdoor travel of that family vary with familial life-cycle in terms of the tourist behavior theory. Such research attempts are likely, firstly, to offer some clues to invigorate inter-communicability among familial stakeholders in determining the travel intention. Secondly, such attempts also expectedly provide better trustability among family members affordable from converged opinions by familial stakeholders. Thirdly, the predictive recognition of factors inducing familial conflicts in a detailed manner is deemed to lead to reduced trial and error in determining decisions among family members.

• Journal of the Korean Magnetics Society
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• 제8권6호
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• pp.357-361
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• 1998

For CoZr/Ag/CoCr trilayered films deposited by DC and FR magnetron sputtering method, ferromagentic resonance experiments have been used to investigate the dependence of the exchange coupling between CoZr and CoCr layers separated by Ag layer on the thickness of the Ag layer. The coupling strength K increases with increasing Ag thickness up to 10 $\AA$ with a maximum value of 748 Oe, but oscillates with increasing Ag thickness in the range from 20 to 100 $\AA$. The coupling strength is positive for all samples. Hence, it seems that the exchange coupling between CoZr and CoCr layers separated by Ag layer is ferromagnetic.

• Journal of the Korean Geophysical Society
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• 제7권4호
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• pp.313-324
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• 2004

The finite element method and statistics of the convergence measurement are useful method of the stability analysis of the tunnel adjacent to the pier. It is the purpose of the this case study to certificate of validity of the application of those methods. The safety of the pilot tunnel method and LW pre-grouting has been evaluated from the FEM analysis. The three-dimensional finite element method is carried out for the decision of the level of stress redistribution at the two-dimensional numerical analysis. An analysis of the convergence is carried out by the estimation of preceding convergence at tunnel excavation. F-examination is applied for this estimation. As results of that analysis, The F-value is from 10.81 to 158.74 and the coefficient of determination is from 0.82 to 0.99. An analysis of convergence is carried out by using regression analysis. Consequently, it is shown that the convergence can be modeled as following function C(t) = a[1-exp(-bt)].