• 전기의세계
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• v.21 no.3
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• pp.48-52
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• 1972

The application of pontryagin's Maximum Principle to the optimal control eventually leads to the problem of solving the two point boundary value problem. Most of problems have been related to their own special factors, therfore it is very hard to recommend the best method of deriving their optimal solution among various methods, such as iterative Runge Kutta, analog computer, gradient method, finite difference and successive approximation by piece-wise linearization. The gradient method has been applied to the optimal control of two point boundary value problem in the power systems. The most important thing is to set up some objective function of which the initial value is the function of terminal point. The next procedure is to find out any global minimum value from the objective function which is approaching the zero by means of gradient projection. The algorithm required for this approach in the relevant differential equations by use of the Runge Kutta Method for the computation has been established. The usefulness of this approach is also verified by solving some examples in the paper.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.109-117
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• 2016

Recently, corporate environment is faced with uncertainty that did not suffer in the past. In addition, as the supply chain was expanded and lengthened, the flow of information and material was complicated. Increase in complexity which amplifies the variability of the individual steps in supply chains further adds to the uncertainty. The bullwhip effect that refers the phenomenon where order variability increases as the orders move upstream in the supply chain became serious. The bullwhip effect is more and more important especially for the enterprise in the supply chain. So, there are many studies now since it was observed about 100 years ago. The aim of this paper is to analyze how to solve the bullwhip effect by using TRIZ (Teoriya Resheniya Izobretatelskikh Zadach). TRIZ is one of the most famous tools for creative solving that applied in many fields ranging from management as well as engineering. Among problems, the dilemma needs creative solutions that require handling the contradictions inherent in that. Among various kinds of problem solving techniques, TRIZ provides the concept of physical contradiction as a common problem solving principle. This study provides a simple process of solving problem explains a case of solving problem in the management field and shows the availability of theory in the inventory control. In accordance with the proposed solving process, the paper analyzes the bullwhip effect by applying the TRIZ tools and then identifies the solution directions. Next, the current studies are classified by the above analysis and important managerial concepts are proposed. Lastly, directions for future research on this area are suggested.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.77-84
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• 2014

TRIZ was developed and refined in the Soviet Union between 1946 and 1985 by Genrich Altshuller. Its primary application has been for solving inventive problems in the areas of engineering. But, recently the elements of TRIZ began to be applied non-technical areas by Darrell Mann. TRIZ theroy was brought into South Korea in 1995 and it is used by the LG, SAMSUNG, POSCO. TRIZ is simply not the tool for technical problem solving, covering many areas of comprehensive approach is being recognized. TRIZ is a methodology for defining problem, finding root cause through RCA(Root cause analysis), defining technical contradiction and physical contradiction. TRIZ overcomes contradiction and purses problem solving method through innovation. TRIZ is a problem solving method in this study using the principles of non-technical fields applied to the improvement of the logistics area study. The method to overcome contradiction is 40 principles. It is possible to generate idea by using 40 principles. This study was applied to logistics field of non-technical area by using TRIZ principle.

• Research in Community and Public Health Nursing
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• v.8 no.1
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• pp.133-143
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• 1997

This study measures the subjectivity of nursing students' experience in community fields through community nursing practice. The purpose of this study is as follows: 1) to find out typologies based on opinions and attitudes toward community nursing practice. 2) to describe the characteristic of each type. 3) to provide alternative strategies for solving community nursing practice problems. A Q-Methodological method was used for that purpose. As a research method, Q-statements were collected through indepth interviews and review of the current literature. For this study 34 Q-statements were selected. 24 nursing students were subjects for the research. The 24 nursing students sorted 34 Q-statements using the principle of Forced Normal Distribution. The principle of Forced Normal Distribution, which has nine scales to measure individual opinions, was called, a Q- Factor Analysis by using a PC Quanl Program to supply the material. According to the results of this study, there were three categories of opinion concerning community nursing practice. The first type is the realistic problem-oriented approach: the second type is the self-responsibility or pursuit of life meaning approach: the third type is the group approach for problem solving. As a result, we need to develop and revise a more realistic way of community nursing practice for nursing students. Finally, the result of this study will provide to the educational program alternative strategies for community nursing practice for nursing students.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.3
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• pp.120-130
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• 2001

We present an approach to parallelizing optimal power flow that is suitable for distributed implementation and is applicable to very large interconnected power systems. This approach can be used by utilities to optimize economy interchange without disclosing details of their operating costs to competitors. Recently, it is becoming necessary to incorporate contingency constraints into the formulation, and more rapid updates of telemetered data and faster solution time are becoming important to better track changes in the system. This concern led to a research to develop an efficient algorithm for a distributed optimal power flow based on the Auxiliary Problem Principle and to study the convergence rate improvement of the distributed algorithm. The objective of this paper is to find a set of control parameters with which the Auxiliary Problem Principle (Algorithm - APP) can be best implemented in solving optimal power flow problems. We employed several IEEE Reliability Test Systems, and Korea Power System to demonstrate the alternative parameter sets.

• The Mathematical Education
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• v.42 no.3
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• pp.387-402
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• 2003

Realistic Mathematics Education (RME) focuses on guided reinvention through which students explore experientially realistic context problems to develop informal problem solving strategies and solutions. This research applied this philosophy of RME to design a differential equation course at a university level. In particular, the course encouraged the students of the course to use numerical methods to solve differential equations. In this context, the purpose of this research was to describe the developmental process in which the students constructed and reinvented Euler algorithm in the class. For the purpose, this paper will present the didactical principle of RME and describe the process of developmental research to investigate the inferential process of students in solving the first order differential equation numerically. Finally, the qualitative analysis of the students' reasoning and use of symbols reveals how the students reinvent Euler algorithm under the didactical principle of guided reinvention. In this research, it has been found that the students developed deep understanding of Euler algorithm in the class. Moreover, it has been shown that the experience of doing mathematics in the course had a positive impact on students' mathematical belief and attitude. These findings imply that the didactical principle of RME can be applied to design university mathematical courses and in general, provide a perspective on how to reform mathematics curriculum at a university level.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1009-1012
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• 1993

An association memory, solving an optimization problem, a Boltzmann machine scheme learning and a back propagation learning in our chaos neuron models are reviewed and some new results are presented. In each model its microscopicrule (a parameter of a chaos system in a neuron) is subject to its macroscopic state. This feedback and chaos dynamics are essential mechanisms of our model and their roles are briefly discussed.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.5
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• pp.592-599
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• 1998

In this paper, we design a tracking controller which satisfies transient response specifications and maintains tracking error within a tolerable limit for the uncertain track-following system of an optical disk drive. To this end, a robust $H_{\infty}$ control problem with regional stability constraints and sinusoidal disturbance rejection is considered. The internal model principle is used for rejecting the sinusoidal disturbance caused by eccentric rotation of the disk. We show that a condition satisfying the regional stability constraints can be expressed in terms of a linear matrix inequality (LMI) using the Lyapunov theory and S-procedure. Finally, a tracking controller is obtained by solving an LMI optimization problem involving two linear matrix inequalities. The proposed controller design method is evaluated through an experiment.

• Korean Journal of Child Studies
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• v.23 no.1
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• pp.55-70
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• 2002

The influence of peer collaboration on children's analogical abilities was studied with 120 9-year-old participants. After the pre-test, which determined the analogical level of the children, each child was assigned to 1 of 4 different learning conditions: cued/non-cued peer collaborative learning, or cued/non-cued individual learning conditions. The post-test showed changes in their analogical abilities. That is, results showed that cued peer collaborative learned improved the analogical abilities of the children, but the pattern of improvement was different by prior level of analogical abilities. We explained improvement in analogical ability by the context effect of peer collaborative learning and by the interactive effect of context with basic cognitive abilities of the children. We suggested implications of the present results for educational practice.

• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.3
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• pp.63-80
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• 2007

This study is a generalization of 'stable dynamics' recently suggested by Nesterov and de Palma[29]. Stable dynamics is a new model which describes and provides a stable state of congestion in urban transportation networks. In comparison with user equilibrium model that is common in analyzing transportation networks, stable dynamics requires few parameters and is coincident with intuitions and observations on the congestion. Therefore it is expected to be an useful analysis tool for transportation planners. An equilibrium in stable dynamics needs only maximum flow in each arc and Wardrop[33] Principle. In this study, we generalize the stable dynamics into the model with multiple traffic classes. We classify the traffic into the types of vehicle such as cars, buses and trucks. Driving behaviors classified by age, sex and income-level can also be classes. We develop an equilibrium with multiple traffic classes. We can find the equilibrium by solving the well-known network problem, multicommodity minimum cost network flow problem.