• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.747-752
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• 1994

Ussing's flux ratio theorem (1978) reflects a reciprocal relationship behavior between the unidirectional fluxes in asymmetric steady diffusion-convection in a membrane slab. This surprising result has led to many subsequent studies in a wide range of applications, in particular involving linear models of time dependent problems in biology and physiology. Ussing's theorem and its extensions are inherently linear in character. It is of considerable interest to ask to what extent these results apply, if at all, in situations involving, for example, nonlinear reaction. A physiologically interesting situation has been considered by Weisiger et at. (1989, 1991, 1992) and by McNabb et al. (1990, 1991) who studied the role of albumin in the transport of ligands across aqueous diffusion barriers in a liver membrane slab. The results are that there exist reciprocal relationships between unidirectional fluxes in the steady state, although albumin is chemically interacting in a nonlinear way of the diffusion processes. However, the results do not hold in general at early times. Since this type of study first started, it has been speculated about when and how the Ussing's flux ratio theorem fails in a general diffusion-convection-reaction system. In this paper we discuss the validity of Ussing-type theorems in time-dependent situations, and consider the limiting time behavior of a general nonlinear diffusion system with interaction.

• Journal of Advanced Marine Engineering and Technology
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• 제5권1호
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• pp.20-27
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• 1981

The alignment of propulsion shaft systems by the fair curve method has been developed over the past twenty years and in recent years its basic problems have been almost solved. At the present time, studies on introducing actual conditions are being undertaken. In a fair curve alignment, its aim is to achieve a stable shaft system which will be relatively insensitive to misalignment or the influence of external factors such as thermal variations due to the sunshine, speed change, etc. The key point of fair curve alignment is the calculations of reactions in the straight support and reaction influence numbers. The present authors have developed those calculating method by the matrix method of the three-moment theorem. The fair curve alignment is based on the analysis of propulsion shaft system which is assumed as a continous beam on multiple support points. The propeller shaft is divided into several elements. For each element, the nodal point equation is derived by the three-moment theorem. Reaction of supporting points of straight shaft and reaction influence numbers are calculated by the matrix calculation of each nodal point equation. It has been found that results of calculation for the model shaft agree well with those of experiment which had been measured by the strain gauge method. Results of calculation for the actual propulsion shafting of the steam turbine had been compared also with those of Det norske Vertas.

• 대한수학회논문집
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• 제14권2호
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• pp.429-440
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• 1999

In this paper an electrochemistry model which consists of three charged species is considered. A dissociation-association reaction is allowed to take place between these species. The species of ions diffuse owing to concentration gradients and migrate because of electric forces. We prove that any initial distribution of species concentrations will settle down to the unique steady state as time becomes large.

• 한국전자파학회논문지
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• 제20권7호
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• pp.617-624
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• 2009

본 논문에서는 가역 정리에 기초한 반응 이론을 이용하여 유도탄 및 항공기 등에 적용되는 원뿔형 비구면 레이돔에 대한 전자파 성능 해석 방법을 제안하였으며 제작된 레이돔에 대한 전자파 성능 측정 결과를 해석 결과와 비교함으로써 제안한 해석 방법의 타당성을 검증하였다. 안테나는 "X" 형태의 2축 모노펄스 구조를 갖는 도파관 슬롯 배열 안테나로 가정하였다. 레이돔 형상은 본 칼만 형태로 가정하였으며, 레이돔 길이 대 직경비를 2:1 로 가정하였다. 실제 제작된 레이돔에 대한 전자파적 특성은 레이돔 전용 측정 장비를 이용하여 측정하였으며, 레이돔 측정 결과가 본 논문에서 제시한 해석 기법을 이용하여 해석한 결과와 잘 일치하는 것을 확인하였다. 본 논문에서 개발한 해석 기법은 유도탄이나 항공기용 레이돔 개발에 적용할 수 있을 것으로 기대된다.

• 한국수학사학회지
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• 제29권1호
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• pp.31-44
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• 2016

This essay aims to suggest roughly the "philosophy of limits." The limits mainly refer to those of human experiences and rational thoughts. The philosophy of limits consist of three theses and two consequences(L, M). (1) The limits are necessarily supervenient in the course of searching knowledge. (2) The limits cannot be dissipated ultimately. (3) To recognize the limits is not only an intellectual recognition but also a beginning of whole personality's reaction. (L) It is a rational decision to accept the limits and leave the margins (yeoback/yeoheuck) rather than to try to remove them. (M) To leave the margins (yeoback/yeoheuck) is characteristic of being human, and enables one to harmoniously communicate with others. To justify the philosophy of limits, this essay examine the limits discussed in mathematics and philosophy: set theory, Godel's Incompleteness Theorem, Galois Theorem in mathematics; and Hume, Kant, Kierkegaard, and Wittgenstein in philosophy. I try to interpret consciousness of limits in various cultures. I claim that consciousness of the limits contribute to lucidity of human identity, communication between persons, stimulation of creative thinking.

• 전기학회논문지
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• 제59권12호
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• pp.2179-2189
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• 2010

This paper deals with analytical techniques for performance evaluation of small scaled wind power generator with outer permanent magnet rotor. In part (1), using transfer relations theorem, magnetic field distribution characteristics by PM and armature reaction field are derived. Moreover, electrical parameters such as back-EMF, inductance and resistance are calculated from the obtained field characteristic equations. The proposed analytical techniques are validated by nonlinear finite element method using commercial software 'Maxwell' and performance experiments of the manufactured generator. In part (2), generating characteristics analysis such as constant speed characteristics and constant resistive load characteristics, and performance evaluation according to variation of wind speed will be accomplished using the derived electrical parameters.

• Journal of Advanced Marine Engineering and Technology
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• 제2권1호
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• pp.3-14
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• 1978

The authors have developed a calculating method of propeller shaft alignment by the finite element method. The propeller shaft is divided into finite elements which can be treated as uniform section bars. For each element, the nodal point equation is derived from the stiffness matrix, the external force vector and the section force vector. Then the overall nodal point equation is derived from the element nodal point equation. The deflection, offset, bending moment and shearing force of each nodal point are calculated from the overall nodal point equation by the digital computer. Reactions and deflections of supporting points of straight shaft are calculated and also the reaction influence number is derived. With the reaction influence number the optimum alignment condition that satisfies all conditions is calculated by the simplex method of linear programming. All results of calculation are compared with those of Det norske Veritas, which has developed a computor program based on the three-moment theorem of the strength of materials. The authors finite element method has shown good results and will be used effectively to design the propeller shaft alignment.

• Structural Engineering and Mechanics
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• 제54권4호
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• pp.793-807
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• 2015

Constructing the influence lines of forces of statically indeterminate structures is a traditional issue in structural engineering and mechanics. However, the existing kinematic method for establishing these force influence lines is an indirect or mixed approach by combining the force method with the theorem of reciprocal displacements, which is yet inconsistent with the kinematic method for statically determinate structure. This paper proposes the direct kinematic method in conjunction with the load-displacement differential relation for exactly constructing influence lines of reaction and internal forces of indeterminate structures. Firstly, through applying the principle of virtual displacement, the formula for influence lines of reaction and internal forces of indeterminate structure via direct kinematic method is derived based on the released structure. Then, a computational approach with a clear concept and unified procedure as well as wide applicability based on the load-displacement differential relation of beam is suggested to achieve conveniently the closed-form expression of force influence lines, and exactly draw them. Finally, three representative examples for constructing force influence lines of statically indeterminate beams and frame illustrate the superiority of the proposed method.

• 한국항공우주학회지
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• 제41권2호
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• pp.98-106
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• 2013

본 논문에서는 슬라이딩 모드 제어와 간단한 적응 법칙을 이용하여 반작용 휠 고장에 대한 고장 허용 제어 법칙을 제안한다. 위성의 동역학식에 시스템 파라미터 오차와 고장 불확실성을 고려하여 자세 제어 법칙을 설계하였다. 고장은 구동기 고장인 반작용 휠 고장만을 고려하였으며, 반작용 휠 고장은 곱 형태로 반영된다. 제안된 자세 제어 법칙은 르야프노프 안정성 이론을 통해 안정성을 확인하였고, 수치 시뮬레이션을 통하여 기존의 슬라이딩 모드 제어기와 비교하였으며 위성의 자세 각속도가 안정화되지 않은 경우 제안된 적응 슬라이딩 자세 제어기가 고장에 더욱 빠른 응답 속도를 갖는 것을 확인하였다.

• 한국통신학회논문지
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• 제18권10호
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• pp.1461-1468
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• 1993

본논문은 임의의 유전율 텐서를 포함하는 비등방성 매질에 비스듬하게 입사되는 전파문제를 변분유한 요소법을 통하여 고찰하였다. 먼저, 변분수식은 유기정리, 리액션 이론, 가역정리에 기초한 새로운 접근방법을 통해 유도하였다. 그다음, 유한요소법을 이용하여 구해진 범함수로 부터 전파특성을 해석하였다. 또한, magnetoplasma 슬랩에 입사되는 전파에 대한 수치결과를 나타냈다.