• East Asian mathematical journal
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• 제28권3호
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• pp.293-303
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• 2012

Sequential quadratic programming (SQP) has been one of the most important methods for solving nonlinear constrained optimization problems. Recently, filter method, proposed by Fletcher and Leyffer, has been extensively applied for its promising numerical results. In this paper, we present and study an active set SQP-filter algorithm for inequality constrained optimization. The active set technique reduces the size of quadratic programming (QP) subproblem. While by the filter method, there is no penalty parameter estimate. Moreover, Maratos effect can be overcome by filter technique. Global convergence property of the proposed algorithm are established under suitable conditions. Some numerical results are reported in this paper.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1371-1376
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• 2018

Photoplethysmography (PPG) is a convenient method for monitoring a heart rhythm. In addition to specialized devices, smartphones can be used to obtain PPG signals. However, as smartphones are not intended for this purpose, optimization is required to efficiently obtain PPG signals. Determining the optimal region of interest (ROI) is one such optimization method. There are two significant advantages in employing an optimized ROI. One is that the computing load is decreased by reducing the image size used to extract the PPG signal. The other is that stronger and more reliable PPG signals are obtained by removing noisy regions. In this paper, we propose an optimal ROI determination method by recursively splitting regions to locate the region that produces the strongest PPG signal.

• 한국지능시스템학회논문지
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• 제19권2호
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• pp.191-196
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• 2009

본 논문에서는 BPSO(Binary Particle Swarm Optimization)방법과 상호정보량을 이용한 속성선택기법을 제안한다. 제안된 방법은 상호정보량을 이용한 후보속성부분집합을 선택하는 단계와 BPSO를 이용한 최적의 속성부분집합을 선택하는 단계로 구성되어 있다. 후보속성부분집합 선택 단계에서는 독립적으로 속성들의 상호정보량을 평가하여 순위별로 설정된 수 만큼 후보속성들을 선택한다. 최적속성부분집합 선택 단계에서는 BPSO를 이용하여 후보속성부분집합에서 최적의 속성부분집합을 탐색한다. BPSO의 목적함수는 분류기의 정확도와 선택된 속성 수를 포함하는 다중목적함수(Multi-Object Function)을 이용하였다. 제안된 기법의 성능을 평가하기 위하여 유전자 데이터를 사용하였으며, 실험결과 기존의 방법들에 비해 우수한 성능을 보임을 알 수 있었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.187-189
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• 2003

Almost all building/infrastructures made of composite materials are fabricated without proper design. Unlike airplane or automobile parts, prototype test is impossible. One cannot destroy 10 story buildings or 100-meter long bridges. People try to build 100-story buildings or several thousand meter long bridges. In order to realize "composites in construction", the following subjects must be studied in detail, for his design: Concept optimization, Simple method of analysis, Folded plate theory, Size effects in failure, and Critical frequency. Unlike the design procedure with conventional materials, his design should include material design, selection of manufacturing methods, and quality control methods, in addition to the fabrication method.on method.

• 한국멀티미디어학회논문지
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• 제11권12호
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• pp.1758-1764
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• 2008

In this paper, we propose query restructure method which realizes not only to present the result from database in Web page but also to adapt user's browsing environments. Recently, wireless PDA (Personal Digital Assistant) and portable phone and terminals equipped with Web browser become very popular. Various browsers would be required to create the HTML which adapt to the user's browsing environment. We propose an adaptive data presentation system which is an extension of SQL which creates HTML pages dynamically adapting to the size of screen. In our proposed method, the three basic rules for the layout conversion are provided and applying these rules, an efficient layout conversion technique optimized to user environment is proposed. Moreover, we propose a standard for converting layouts and a layout optimization for adaptive conversion of layouts.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.433-436
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• 2003

In this paper, the efficient motion estimation and compensation method for 3 dimensional wavelet transform is proposed. Recently, since the compression performance and scalable functionality are provided by wavelet transform, many researches have been carried out for applying to the video compression. For the temporal filtering, motion estimation and compensation techniques are used, but the unconnected pixels, which are produced by motion compensation result into the degradation of coding performance and quality of the picture. For the efficient motion compensated temporal filtering by reducing the number of these unconnected pixels, we propose the variable block size motion estimation and compensation method. Also we propose a method that determines the block size using rate-distortion optimization technique according to the local characteristics of the frame. The simulation results show the improved performances than the MPEG-4 scalable coding methods and the 3 dimensional wavelet coding methods using fixed block size motion estimation and compensation.

• 한국공간구조학회논문집
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• 제8권4호
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• pp.47-55
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• 2008

이 논문은 지오데식 돔 구조물의 구조최적화에 대한 연구내용과 관련이론 그리고 수치해석결과를 기술하고 있다. 지오데식 돔의 공간 효율성을 알아보기 위해 돔의 기저인 정이십면체의 외피면적과 내부공간의 비율을 계산하고 건축구조물에서 나타나는 다른 입방체의 값과 정량적으로 비교하였다. 지오데식 돔을 형성하기 위한 절차를 세부적으로 정리하고 이를 프로그래밍하여 설계최적화프로그램 ISADO-OPT에 연동하였다. 본 연구에서는 반구 형태의 지오데식 돔이 집중하중에 효율적으로 저항할 수 있는 최적의 부재크기 패턴을 조사하기 위하여 수학적 프로그래밍 기법을 도입하였다. 이때 최소화해야하는 돔 전체 부재의 중량을 목적함수로 이용하고 하중이 가해지는 절점에서 발생하는 변위 값과 각 부재에서 발생하는 응력 값을 허용치 이하로 제한하는 제약조건으로 사용하였다. 목적함수와 주어진 제약조건을 만족하는 최적 설계변수값을 검색하기 위해 설계변수에 대한 목적함수의 민감도 값을 유한차분법을 이용하여 계산하였다. 본 연구에서 기술한 지오데식돔을 위한 설계최적화 기본이론을 바탕으로 도출한 최적 부재패턴은 향후 돔의 최적설계에 기본 벤치마크테스트결과로 유용하게 사용될 것으로 판단된다.

• 융합신호처리학회논문지
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• 제11권3호
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• pp.250-254
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• 2010

As the number of input and fuzzy set of a fuzzy system increase, the size of the rule base increases exponentially and becomes unmanageable (curse of dimensionality). In this paper, tree architectures of fuzzy controller (TAFC) is proposed to overcome the curse of dimensionality problem occurring in the design of fuzzy controller. TAFC is constructed with the aid of AND and OR fuzzy neurons. TAFC can guarantee reduced size of rule base with reasonable performance. For the development of TAFC, genetic algorithm constructs the binary tree structure by optimally selecting the nodes and leaves, and then random signal-based learning further refines the binary connections (two-step optimization). An inverted pendulum system is considered to verify the effectiveness of the proposed method by simulation.

• ETRI Journal
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• 제35권2호
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• pp.270-280
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• 2013

A fast intra-prediction method is proposed for High Efficiency Video Coding (HEVC) using a fast intra-mode decision and fast coding unit (CU) size decision. HEVC supports very sophisticated intra modes and a recursive quadtree-based CU structure. To provide a high coding efficiency, the mode and CU size are selected in a rate-distortion optimized manner. This causes a high computational complexity in the encoder, and, for practical applications, the complexity should be significantly reduced. In this paper, among the many predefined modes, the intra-prediction mode is chosen without rate-distortion optimization processes, instead using the difference between the minimum and second minimum of the rate-distortion cost estimation based on the Hadamard transform. The experiment results show that the proposed method achieves a 49.04% reduction in the intra-prediction time and a 32.74% reduction in the total encoding time with a nearly similar coding performance to that of HEVC test model 2.1.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권4호
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• pp.207-223
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• 2015

In this paper a method for simultaneous swift non-linear analysis and optimal design/posture of mechanical/biomechanical systems is presented. The method is developed to get advantages of iterations in non-linear analysis and/or generations in genetic algorithm (GA) for the purpose of efficient analysis within the optimal design/posture. The method is applicable for both size and geometry optimizations wherein material and geometry non-linearity are present. In addition to established mechanical systems, the method can solve biomechanical models of human musculoskeletal system. Optimization-based procedures are popular methods for resolving the redundancy at joints wherein the number of unknown muscle forces is far more than the number of equilibrium equations. These procedures involve optimization of a cost function(s) which is assumed to be consistent with the central nervous system's strategy when activating muscles to assure equilibrium. However, because of the complexity of biomechanical problems (i.e., due to non-linear biomaterial, large deformation, redundancy of the problem and so on) efficient analysis are required within optimization procedures as suggested in this paper.