• 대한수학회지
• /
• 제54권1호
• /
• pp.87-99
• /
• 2017

To indicate the statistical complexity of dynamical systems, we introduce the notions of higher order irregular set and higher order maximal Birkhoff average oscillation in this paper. We prove that, in the setting of topologically mixing Markov chain, the set consisting of those points having maximal k-order Birkhoff average oscillation for all positive integers k is as large as the whole space from the topological point of view. As applications, we discuss the corresponding results on a repeller.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
• /
• pp.1119-1120
• /
• 2007

Nano-sized metal patterns were successfully fabricated on flexible PET substrate using nanoimprint lithography. 70nm line and space PMMA resist pattern was formed on PET substrate without residual layer by 'artial filling effect' and 20nm thin Cr metal layer was deposited by e-beam evaporation. Then, PMMA resist was selectively removed by acetone and 70nm narrow Cr pattern was formed.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제16권1호
• /
• pp.1-13
• /
• 2012

In this paper we present an a posteriori error estimator for the stabilized P1 nonconforming finite element method of the linear elasticity problem based on a nonsymmetric H(div)-conforming approximation of the stress tensor in the first-order Raviart-Thomas space. By combining the equilibrated residual method and the hypercircle method, it is shown that the error estimator gives a fully computable upper bound on the actual error. Numerical results are provided to confirm the theory and illustrate the effectiveness of our error estimator.

• 대한전기학회논문지
• /
• 제37권6호
• /
• pp.414-421
• /
• 1988

This paper is concerned with a design procedure for constructing finite dimensional compensators for a class of infinite dimensional aystems. Basically, this procedure consists of decomposing the state space of the basis of its modes and utilizing well-known finite dimensional algorithms for constructing observers and state feedback control laws. The finite dimensional observer dynamics is modified to account for the effect of the residual modes so as to achieve the stabelity of the closed loop system asymptotically.

• Journal of applied mathematics & informatics
• /
• 제23권1_2호
• /
• pp.193-203
• /
• 2007

In this paper we consider the inverse minimum flow (ImF) problem, where lower and upper bounds for the flow must be changed as little as possible so that a given feasible flow becomes a minimum flow. A linear time and space method to decide if the problem has solution is presented. Strongly and weakly polynomial algorithms for solving the ImF problem are proposed. Some particular cases are studied and a numerical example is given.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2007년도 춘계학술발표회 초록집
• /
• pp.24-25
• /
• 2007

Nano-sized metal patterns were successfully fabricated on flexible PET substrate using nanoimprint lithography. 70nm line and space PMMA resist pattern was formed on PET substrate without residual layer by "partial filling effect' and 20nm thin Cr metal layer was deposited by e-beam evaporation. Then, PMMA resist was selectively removed by acetone and 70nm narrow Cr pattern was formed.

• 한국항공우주학회지
• /
• 제31권4호
• /
• pp.8-15
• /
• 2003

본 연구는 적분 방정식과 반복 "오차-수정" 개념을 이용하는 Takanashi의 이론에 기초한 초음속 실용적인 설계방법의 개발 결과로서, 형상의 수정량은 목표 압력분포와 설계대상의 압력분포와의 차를 경계조건으로 이용해 LSP 방정식을 풀므로써 계산되어진다. 이 연구에서는 Green의 정리를 이용하여 편미방정식 형태의 LSP 방정식을 적분방정식으로 변환하여 계산하는 방법을 이용하고 있다. 여기서는 Isolated wing과 wign-nacelles 두가지 경우의 설계를 예로 들었다.

• 소음진동
• /
• 제6권5호
• /
• pp.567-574
• /
• 1996

This paper concerns an articulated space robot with flexible links. The equations of its motion are derived by means of the Lagrangian mechanics. Assuming that magnitude of elastic motions are relatively small, the perturbation approach is taken to separate the original equations of motion into linear and nonlinear equations. Th effect the desired payload motion, open loop control inputs are first determined based on the nonlinear equations. One the other hand, in order to reduce the positional errors during the maneuver, vibration suppression is actively done with a feedforward control for disturbance cancellation to some extent. Additionally, for performance robustness against residual disturbance, an LQ control modified to have a prescribed degree of stability is applied based on the linear equations. Measurement equations are formulated to be used for the maximum likelihood estimator to reconstruct states from the original robot equations of motion. Finally, numerical simulations show effectiveness of the proposed control design scheme.

• Journal of Chest Surgery
• /
• 제26권5호
• /
• pp.390-394
• /
• 1993

This study elvaluated clinically the surgical results of the thirty-eight patients who had exploratory thoracotomy for spontaneous pneumothorax between Jan. 1989 and Nov. 1992. Thirty three, or 86.8%, of the patients were male. The most frequent age of the spontaneous pneumothorax requiring thoracotomy was between fifteen years and twenty years. Sudden onset dyspnea and chest pain, which developed in thirty-five patients[89.5%], were the major chief complaints. Bleb and Bulla located in the both upper lobes were the most frequent causes of spontaneous pneumothorax for exploratory thoracotomy. There was no operative death. Postoperative morbidity included three cases of residual air space in the apical pleural space, tow cases of atrial fibrillation, and one each case of reoperation for bleeding, mediasitinitis, and sternal osteomyelitis. All postoperative complications were treated without any serious problems. This study suggests that early exploratory thoracotmy is desirable for patients with prolonged air-leak, massive air-leak, or multiple blebs and giant bullae on the computed tomography of the chest.

• International Journal of Aeronautical and Space Sciences
• /
• 제15권2호
• /
• pp.113-122
• /
• 2014

The objective of the paper is to clarify a methodology based on the use of the existing component mode synthesis methods for the case of two damped substructures which are coupled through a linking viscoelastic flexible substructure and for which the structural modes with free geometrical interface are used for each main substructure. The proposed methodology corresponds to a convenient alternative to the direct use either of the Craig-Bampton method applied to the three substructures (using the fixed geometric interface modes) or of the flexibility residual approaches initiated by MacNeal (using the free geometric interface modes). In opposite to a geometrical interface which is a topological interface on which there is a direct linkage between the degrees of freedom of substructures, we consider a physical flexible interface which exists in certain present technologies and for which the general framework linear viscoelasticity is used and yields a frequency-dependent damping and stiffness matrices of the physical flexible interface.