• Journal of applied mathematics & informatics
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• v.30 no.5_6
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• pp.759-772
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• 2012

In this paper, semi-infinite constrained programming, a class of constrained nonsmooth optimization problems, are transformed into unconstrained nonsmooth convex programs under the help of exact penalty function. The unconstrained objective function which owns the primal-dual gradient structure has connection with $\mathcal{VU}$-space decomposition. Then a $\mathcal{VU}$-space decomposition method can be applied for solving this unconstrained programs. Finally, the superlinear convergence algorithm is proved under certain assumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1402-1413
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• 2004

In non-rigid image registration, the Jacobian determinant of the estimated deformation should be positive everywhere since physical deformations are always invertible. We propose a constrained optimization technique at ensures the positiveness of Jacobian determinant for cubic B-spline based deformation. We derived sufficient conditions for positive Jacobian determinant by bounding the differences of consecutive coefficients. The parameter set that satisfies the conditions is convex; it is the intersection of simple half spaces. We solve the optimization problem using a gradient projection method with Dykstra's cyclic projection algorithm. Analytical results, simulations and experimental results with inhale/exhale CT images with comparison to other methods are presented.

• Journal of applied mathematics & informatics
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• v.4 no.1
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• pp.167-178
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• 1997

In this paper we present an application to airfoil design of an optimum design method based on optimal control theory. The method used here transforms the design problem by way of a change of variable into an optimal control problem for a distributed system with Neumann boundary control. This results in a set of variational inequalities which is solved by adding a penalty term to the differential equation. This si inturn solved by a finite element method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.4
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• pp.121-127
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• 1983

In this paper an efficient algorithm for Pontriagin's maximum principle is developed. Fletcher-Powell method is adopted as optimization technique which shows fast and stable convergence characteristics. Terminal constraints are alse considered by using Hestens' algorithm and penalty function method together. Control variable inequality constraints are also considered by using Gradient Projection technique combined with Flectcher-Powell method. Test experiment shows good and reliable results.

• International Journal of Railway
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• v.2 no.2
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• pp.70-79
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• 2009

An optimal driving strategy of a train in a long journey on a nonsteep track has four phases: an initial power phase, a long hold speed phase, a coast phase and a final brake phase. The majority of the journey is speed holding. On a track with steep gradients, it becomes necessary to vary the strategy around steep sections of track because it is not possible to hold a constant steep on steep track. Instead we must interrupt the speed hold phase with a power phase. The aim of this paper is to show that there is a unique power phase that satisfies the necessary conditions for an optimal journey. The problem is developed and solved for various cases, from a simple single steep gradient to a complicated multiple steep gradient section. For each case, we construct a set of new conditions for optimality of the power phase that minimises the energy used during the power phase subject to a weighted time penalty. We then use the new necessary conditions to develop a calculate scheme for finding an optimal power phase for a steep incline. We also present an example to confirm the uniqueness of an optimal power phase.

• Journal of the Korean Mathematical Society
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• v.38 no.1
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• pp.1-23
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• 2001

This paper is concerned with an optimal shape control problem for the stationary Navier-Stokes system. A two-dimensional channel flow of an incompressible, viscous fluid is examined to determine the shape of a bump on a part of the boundary that minimizes the viscous drag. by introducing an artificial compressibility term to relax the incompressibility constraints, we take the penalty method. The existence of optima solutions for the penalized problem will be shown. Next, by employing Lagrange multipliers method and the material derivatives, we derive the shape gradient for the minimization problem of the shape functional which represents the viscous drag.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.46-52
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• 2016

We propose a new type of semi-global matching (SGM) in order to solve a streaking problem arising from conventional SGM. Conventional SGM imposes a penalty to a pixel when the disparity of the pixel differs from that of the previous pixel along a scan path, and thus, disparity changes are not easily allowed, causing the streaking effect. The road surface is an appropriate target for such an effect, because the colors of the surfaces are very similar, and the image pixels corresponding to the surfaces show disparities that change very smoothly along the viewing direction. In contrast to conventional SGM, the new type of SGM imposes penalties depending on the disparity gradients, and thus, the streaking effect is controlled. The experimental results show the effectiveness of the proposed SGM method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.3
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• pp.443-452
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• 1992

본 연구에서는 소성가공 공정의 최적설계를 위한 새로운 접근 방법이 소개 된다.이방법은 소성가공 공정의 유한요소해석 기술과 기계시스템의 최적설계 기술 에 바탕을 두고 있다. 벌칙 강소성유한요소법, 정상 상태의 소성가공 공정(steady -state metal forming process)을 위한 최적설계 문제의 수식화, 설계민감도의 해석 방법, 설계민감도의 정확성에 관한 고찰, 구배투영법(gradient projection emthod)등 이 본 논문에서 상세하게 소개된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.159-167
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• 2004

The objective of this study is development of the optimum design program to minimize the cost for PSC box girder bridge using the full staging method to indicate the necessity for the optimum design applied many types of bridges. It also considered the proper span length to girder depth ratio and the cell number along the width of bridge. This program used SUMT procedure and Kavlie's extended penalty function to allow infeasible design points in the process. Powell's direct method was used in searching design points and Gradient Approximate Method was used to reduce design hours. This study showed the convergence in design parameter and correlation of totally optimized cost according to cell numbers, span lengths, and lane numbers.

• Journal of Digital Convergence
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• v.19 no.7
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• pp.271-282
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• 2021

This study was conducted to develop a model for predicting the length of stay for premature infants through machine learning. For the development of this model, 6,149 cases of premature infants discharged from the hospital from 2011 to 2016 of the discharge injury in-depth survey data collected by the Korea Centers for Disease Control and Prevention were used. The neural network model of the initial hospitalization was superior to other models with an explanatory power (R²) of 0.75. In the model added by converting the clinical diagnosis to CCS(Clinical class ification software), the explanatory power (R²) of the cubist model was 0.81, which was superior to the random forest, gradient boost, neural network, and penalty regression models. In this study, using national data, a model for predicting the length of stay for premature infants was presented through machine learning and its applicability was confirmed. However, due to the lack of clinical information and parental information, additional research is needed to improve future performance.