• 한국정보통신학회논문지
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• 제17권12호
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• pp.2775-2784
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• 2013

Brachistochrone 문제는 중력장내의 수직평면에 존재하는 임의의 두점을 연결하는 곡선경로를 따라 bead가 움직일 때에 가장 빠른 곡선경로를 구하는 것이며, calculus of variation에 의해 최단시간제어량을 구할 수 있지만 매우 복잡한 비선형방정식의 역관계를 테이블 형태로 구해야 하므로 그 정확도가 높지 않다. 본 논문에서는 이러한 근사해의 정확도를 높이기 위해 신경회로망을 이용하여 비선형방정식의 역관계식을 표현하였고, 신경회로망의 보간 기능으로 인해 높은 정확도의 최단시간제어가 가능하였다. 여러 가지 최종목표점에 대한 컴퓨터 시뮬레이션을 통해서 본 논문에서 제안한 방법이 기존의 방법보다 우수함을 확인할 수 있었다.

• 한국정보통신학회논문지
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• 제17권1호
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• pp.117-126
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• 2013

위치에 따라 변화하는 해류가 있는 해상에서 선박이 일정속도로 움직이면서 진행각도를 제어하여 특정목표점에 최단시간으로 도착하고자 한다. 이러한 문제는 Zermelo의 항해문제라고 불리고 있으며 calculus of variation에 의해 최단시간제어의 근사해를 구할 수 있지만 매우 복잡한 비선형방정식의 역관계를 테이블 형태로 이용하여야 하므로 그 정확도가 높지 않다. 본 논문에서는 이러한 근사해의 정확도를 높이기 위해 신경회로망을 이용하여 비선형 방정식의 역관계식을 표현하였고, 신경회로망의 보간 기능으로 인해 높은 정확도의 최단시간제어가 가능하였다. 여러 가지 항해 상황에 대한 컴퓨터 시뮬레이션을 통해서 본 논문에서 제안한 방법이 기존의 방법보다 우수함을 확인할 수 있었다.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.629-637
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• 2016

본 연구는 구강관리행태와의 연관성과 설태지수, 치석, 스케일링 전후의 구강환경에 따른 구취변화를 알아보고자 대전광역시에 위치한 K대학교 치위생학과에 스케일링 실습을 위해 내방한 참여자 130명을 대상으로 설태지수와 구취를 조사하여 조사하였다. 모든 조사대상자에 대하여 설문조사, 설태지수와 치면세균막과 치석정도를 측정한 구강검사, 구취측정 등을 하였다. 그 결과 설태가 구취에 가장 큰 영향을 준다는 것을 확인할 수 있었고, 이러한 설태지수는 흡연과 혀 닦기와 관련이 높았다. 또한 구취는 잇솔질 횟수가 많을수록 낮은 수치를 보였고 비외과적 치료인 스케일링을 통해 구취감소의 효과가 나타났으며, 나이와 설태지수가 관련요인임을 확인하였다. 이에 적절한 구강관리를 실천하여 치태과 설태의 양을 줄이고 정기적인 스케일링을 받음으로써 구강건강증진은 물론 구취감소의 효과를 얻어야 할 것이다.

• 한국수학사학회지
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• 제27권4호
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• pp.271-283
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• 2014

This study takes a look at Polya's analysis on Archimedes' "The Method" from a math-historical perspective. We, based on the elaboration of Polya's analysis, investigate the analytic geometric characteristics of Archimedes' "The Method" and discuss the way of using the characteristics in education of school calculus. So this study brings up the educational need of approach of teaching the definite integral by clearly disclosing the transition from length, area, volume etc into the length as an area function under a curve. And this study suggests the approach of teaching both merit and deficiency of the indivisibles method, and the educational necessity of making students realizing that the strength of analytic geometry lies in overcoming deficiency of the indivisibles method by dealing with the relation of variation and rate of change by means of algebraic expression and graph.

• 한국수학교육학회지시리즈A:수학교육
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• 제53권3호
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• pp.313-327
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• 2014

'Tangent' is one of the most important concepts in the middle and high school mathematics, especially in dealing with calculus. The concept of tangent in the current textbook consists of the ways which make use of discriminant or differentiation. These ways, however, do not present dynamic view points, that is, the concept of variation. In this paper, after applying 'Roberval's way of finding tangent using vectors in terms of kinematics to parabola, ellipse, circle, hyperbola, cycloid, hypocycloid and epicycloid, we will identify that this is the tangent of those curves. This trial is the educational link of mathematics and physics, and it will also suggest the appropriate example of applying vector. We will also help students to understand the tangent by connecting this method to the existing ones.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.234-239
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• 1993

Most of the control problem is for the redundant manipulators use the pseudo-inverse control, thit is, the redundancy is resolved by the pseudo-inverse of the Jacobian matrix and then the controller is designed based on this resolution. However, this pseudo-inverse control has some problems when the redundant robot repeats the cyclic tasks. This is because the pseudo-inverse resolution is a local solution that generates the different configurations of the robot arm for the same hand position. Therefore it is necessary to find the global solution that maintains the optimal configuration of the robot for the repetitive tasks. In this paper, we want to propose a redundancy resolution method by the optimal theory that uses the calculus of variation. The problem formulations are : first to convert the optimal resolution problem to an optimal control problem and then to resolve the redundancy using the necessary conditions of optimal control.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.547-554
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• 2006

This paper is concerned with an optimal control suspension system using the preview information of road input based on a quarter car model. The main purpose of the control is to combine good vibration isolation characteristics with improved attitude control. The optimal control law is derived with the use of calculus of variation, consisting of three parts. The first part is a full state feedback term that includes integral control acting on the suspension deflection to ensure zero steady-state deflection in response to static body forces and ramp road inputs. The second part is a feed-forward term which compensates for the body forces when they can be detected, and the third part depends on previewed road input. The performance of the suspension is evaluated in terms of frequency domain characteristics and time responses to ramp road input and cornering forces. The effects of each part of the suspension controller on the system behavior are examined.

• 대한수학회지
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• 제54권5호
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• pp.1521-1536
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• 2017

This paper introduces a representation style of variable binding using dependent types when formalizing meta-theoretic properties. The style we present is a variation of the Coquand-McKinna-Pollack's locally-named representation. The main characteristic is the use of dependent families in defining expressions such as terms and formulas. In this manner, we can handle many syntactic elements, among which wellformedness, provability, soundness, and completeness are critical, in a compact manner. Another point of our paper is to investigate the roles of free variables and constants. Our idea is that fresh constants can entirely play the role of free variables in formalizing meta-theories of first-order predicate logic. In order to show the feasibility of our idea, we formalized the soundness and completeness of LJT with respect to Kripke semantics using the proof assistant Coq, where LJT is the intuitionistic first-order predicate calculus. The proof assistant Coq supports all the functionalities we need: intentional type theory, dependent types, inductive families, and simultaneous substitution.

• 전기의세계
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• 제26권6호
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• pp.48-54
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• 1977

The object of this work is to study the optimal control strategy of constant speed characteristics for a D.C control motor under influence of disturbance. In the course of the analysis, the linearization and time invariance schemes on motor dynamics are presumed throughout under certain prescribed conditions and the performance measure for optimality is assumed to be quadratic in state and the control effort, with the initial and final time specified. When the motor speed is deviated from a stationary operating point by any external disturbance, the optimal continuous feedback control law is investigated by the application of the calculus of variation and realizability of the required control meachanism is suggested. Finally, the comparative study of the speed reasponses of the motor, with and without the optimal control effort is also presented to confirm the obtained results.

• 설비공학논문집
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• 제15권2호
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• pp.95-102
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• 2003

Optimization for the insulation thickness and external shape of a household refrigerator is peformed in order to minimize thermal load through the insulation wall. The one dimensional conduction heat transfer model is adopted to calculate thermal load. Calculus of variation is employed to optimize the thickness and shape of refrigerator or freezer. The uniform distribution of an insulation thickness and cubed external shape make thermal load minimize. Finally, by using both of the computational and experimental method, the thermal load is minimized for a refrigerator/freezer. It is shown that there exists optimal thickness of insulation walls and external shape for given the external cabinet dimensions and freezer and refrigerator internal volumes, Also, the analytical results are well agreed with the experimental results.