• Journal of applied mathematics & informatics
• /
• 제29권3_4호
• /
• pp.653-668
• /
• 2011

This paper presents a new hybrid method for solving nonlinear complementarity problems with $P_0$-functions. It can be regarded as a combination of smoothing trust region method with ODE-based method and line search technique. A feature of the proposed method is that at each iteration, a linear system is only solved once to obtain a trial step, thus avoiding solving a trust region subproblem. Another is that when a trial step is not accepted, the method does not resolve the linear system but generates an iterative point whose step-length is defined by a line search. Under some conditions, the method is proven to be globally and superlinearly convergent. Preliminary numerical results indicate that the proposed method is promising.

• Journal of Electrical Engineering and Technology
• /
• 제8권4호
• /
• pp.686-693
• /
• 2013

Generation Expansion Planning (GEP) is one of the most important decision-making activities in electric utilities. Least-cost GEP is to determine the minimum-cost capacity addition plan (i.e., the type and number of candidate plants) that meets forecasted demand within a pre specified reliability criterion over a planning horizon. In this paper, Differential Evolution (DE), and Opposition-based Differential Evolution (ODE) algorithms have been applied to the GEP problem. The original GEP problem has been modified by incorporating Virtual Mapping Procedure (VMP). The GEP problem of a synthetic test systems for 6-year, 14-year and 24-year planning horizons having five types of candidate units have been considered. The results have been compared with Dynamic Programming (DP) method. The ODE performs well and converges faster than DE.

• 전기학회논문지
• /
• 제67권5호
• /
• pp.663-668
• /
• 2018

A combined CPG (Central Pattern Generator) based foot trajectory and GA (Genetic Algorithm) based joint compensation method is presented for adaptive humanoid walking. In order to increase an adaptability of humanoid walking for rough terrains, the experiment for rolling terrains are introduced. The CPG based foot trajectory method has been successfully applied to basic slops and variable slops, but has a limitation for the rolling terrains. The experiments are conducted in an ODE based Webots simulation environment using humanoid robot Nao to verify a stability of walking for various rolling terrains. The proposed method is compared to the previous CPG foot trajectory technique and shows better performance especially for the cascade rolling terrains.

• 전기학회논문지
• /
• 제65권9호
• /
• pp.1551-1556
• /
• 2016

A combined CPG (Central Pattern Generator) based foot trajectory and GP (Genetic Programming) based joint compensation method is presented for the adaptive humanoid walking. The CPG based foot trajectory methods have been successfully applied to basic slops and variable slops with slow rates, but have a limitation for the steep slop terrains. In order to increase an adaptability of humanoid walking for the rough terrains, a GP based joint compensation method is proposed and combined to the CPG (Central Pattern Generator) based foot trajectory method. The experiments using humanoid robot Nao are conducted in an ODE based Webots simulation environmemt to verify a stability of walking for the various aslope terrains. The proposed method is compared to the previous CPG foot trajectory technique and shows better performances especially for the steep varied slopes.

• Journal of Electrical Engineering and Technology
• /
• 제9권1호
• /
• pp.45-51
• /
• 2014

Distribution system is a critical link between customer and utility. The control of power loss is the main factor which decides the performance of the distribution system. There are two methods such as (i) distribution system reconfiguration and (ii) inclusion of capacitor banks, used for controlling the real power loss. Considering the improvement in voltage profile with the power loss reduction, later method produces better performance than former method. This paper presents an advanced evolutionary algorithm for capacitor inclusion for loss reduction. The conventional sensitivity analysis is used to find the optimal location for the capacitors. In order to achieve a better approximation for the current candidate solution, Opposition based Differential Evolution (ODE) is introduced. The effectiveness of the proposed technique is validated through 10, 33, 34 and85-bus radial distribution systems.

• 한국지능시스템학회논문지
• /
• 제17권6호
• /
• pp.843-848
• /
• 2007

본 논문은 휴머노이드 로봇이 넘어질 경우, 충격에 의한 손상을 최소화하기 위한 자세의 자동 생성 방법을 제안한다. 유전알고리즘(GA)를 사용하여 로봇이 선방 또는 후방으로 넘어질 때 충격량등을 최소화 할 수 있는 관절각들의 궤적을 구하였다. 또한, 다양한 적합도 함수를 정의하여 서로 다른 넘어짐 자세를 생성할 수 있도록 하였다. 제안된 기법의 검증을 위하여 Sony QRIO 로봇에 대해서 ODE 기반 물리적 특성의 시뮬레이션이 가능한 Webots를 이용하여 실험을 수행하였다.

• Steel and Composite Structures
• /
• 제17권5호
• /
• pp.753-776
• /
• 2014

In this paper, nonlinear vibration and post-buckling analysis of beams made of functionally graded materials (FGMs) resting on nonlinear elastic foundation subjected to thermo-mechanical loading are studied. The thermo-mechanical material properties of the beams are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents, and to be temperature-dependent. The assumption of a small strain, moderate deformation is used. Based on Euler-Bernoulli beam theory and von-Karman geometric nonlinearity, the integral partial differential equation of motion is derived. Then this PDE problem which has quadratic and cubic nonlinearities is simplified into an ODE problem by using the Galerkin method. Finally, the governing equation is solved analytically using the variational iteration method (VIM). Some new results for the nonlinear natural frequencies and buckling load of the FG beams such as the influences of thermal effect, the effect of vibration amplitude, elastic coefficients of foundation, axial force, end supports and material inhomogenity are presented for future references. Results show that the thermal loading has a significant effect on the vibration and post-buckling response of FG beams.

• Smart Structures and Systems
• /
• 제22권1호
• /
• pp.105-120
• /
• 2018

In this paper, the nonlinear free and forced vibration responses of sandwich nano-beams with three various functionally graded (FG) patterns of reinforced carbon nanotubes (CNTs) face-sheets are investigated. The sandwich nano-beam is resting on nonlinear Visco-elastic foundation and is subjected to thermal and electrical loads. The nonlinear governing equations of motion are derived for an Euler-Bernoulli beam based on Hamilton principle and von Karman nonlinear relation. To analyze nonlinear vibration, Galerkin's decomposition technique is employed to convert the governing partial differential equation (PDE) to a nonlinear ordinary differential equation (ODE). Furthermore, the Multiple Times Scale (MTS) method is employed to find approximate solution for the nonlinear time, frequency and forced responses of the sandwich nano-beam. Comparison between results of this paper and previous published paper shows that our numerical results are in good agreement with literature. In addition, the nonlinear frequency, force response and nonlinear damping time response is carefully studied. The influences of important parameters such as nonlocal parameter, volume fraction of the CNTs, different patterns of CNTs, length scale parameter, Visco-Pasternak foundation parameter, applied voltage, longitudinal magnetic field and temperature change are investigated on the various responses. One can conclude that frequency of FG-AV pattern is greater than other used patterns.

• 한국광학회지
• /
• 제16권3호
• /
• pp.182-190
• /
• 2005

본 논문은 효율적으로 라만 증폭기의 이득을 예측하고 잡음 특성을 분석하기 위해서 라만 증폭기 상관된 상미분방정식 (Ordinary Differential Equation: ODE)을 유효거리(Effective Length) 기반의 상관된 적분형(closed integral form)방정식 및 매트릭스로 전개하고 이 전개를 활용한 라만 증폭기 모델링 및 수치해석 알고리즘을 기술한다. 광섬유 라만 증폭기는 유연하고 넓은 이득 대역폭 및 낮은 잡음 등의 장점 때문에 최근 광통신 시스템에서 핵심기술로 각광받고 있으며, 특히 멀티채널 펌핑구조에서 성능예측을 위해 많은 라만 증폭기 모델링 방법들이 연구되어 왔다. 그러나 기존의 많은 연구들은 라만 증폭기 상관된 상미분방정식의 해를 "fiber propagation axis"를 기반으로 구해왔기 때문에 광섬유 길이에 의존적이고 복잡한 계산으로 상당히 많은 시간이 필요했으며, 실제 전송 시스템에서의 활용이 어려웠다. 이러한 문제점을 해결하기 위해서 본 논문에서는 기존의 상관된 상미분방정식을 접근이 용이한 "유효거리" 기반의 적분형 방정식으로 전개하고 매트릭스 및 벡터 형태로 알고리즘을 공식화하여 빠른 라만 이득 계산과 "iteration axis"를 이용한 해의 도출을 통해 새로운 라만 증폭기 모델링 방법과 수치해석 알고리즘을 제시하였다. 제안한 수치해석 알고리즘을 전방, 후방 및 양방향 펌핑구조의 라만 증폭기가 도입된 시스템에 적용하는 컴퓨터 모의실험을 수행한 결과 기존의 "Average power method와 비교하여 라만 이득과 광선로 내의 펌프 및 신호 광의 진행정도를 18배 이상의 정밀도에서 0.03 dB 이내의 매우 작은 오차범위 및 100배 이상 단축된 짧은 시간으로 정확히 예측하였다. 또한, 수치해석 알고리즘을 통해서 얻은 신호 광 파워의 분포를 바탕으로 Amplified Spontaneous Emission(ASE), 후방 ASE의 레일레이 산란 및 신호의 이중 레일레이 산란과 같은 라만 증폭기 잡음 요소들을 분석하였다. 새롭게 제안한 수치해석 알고리즘은 실제 광통신 시스템에 적용되어 신속하고 효율적으로 라만 증폭기 성능을 예측하고 분석할 수 있을 것으로 기대된다.

• Journal of the Korean Data and Information Science Society
• /
• 제26권2호
• /
• pp.301-312
• /
• 2015

본 연구는 전염병의 확산 과정을 설명하기 위한 질병 확산 모형을 구축 하고자 하였다. 질병의 확산 과정은 결정적인 과정과 확률적인 과정으로 크게 분류할 수 있다. 대부분의 연구가 질병의 확산 과정을 결정적 과정으로 움직인다고 가정을 하고 상미분방정식을 이용하여 모형을 구축하였다. 본 연구에서는 질병 확산 모형인 SIR (Suspectible - Infectious - Recovered) 모형을 기반으로 하여 질병의 확산 예측 모형을 구현하고자 하였다. 최소제곱법을 이용하여 모수를 추정한 후, 상미분방정식을 이용한 결정적 모형 방법과 더불어 Gillespie가 제안한 방법에 기반하여 확률적인 과정을 따르는 모형 적합을 함께 시도하였다. 본 연구에서 소개된 방법들은 질병관리본부의 2001년 1월부터 2002년 3월까지의 국내 말라리아 주별 발병자 수 자료를 이용하여 모형 적합을 시도 하였으며, 그 결과 구현된 모형이 실제 질병의 확산과정을 잘 설명하였다.