• Title/Summary/Keyword: 이중 목적 함수

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DFT를 사용한 고속 constant modulus algorithm 의 성능분석

  • Yang, Yoon-Gi;Lee, Chang-Su;Yang, Soo-Mi
    • Journal of IKEEE
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    • v.13 no.1
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    • pp.1-10
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    • 2009
  • Recently, some frequency domain CMA (Constant Modulus Algorithm) have been introduced in an effort to reduce computational complexities [1,2]. In [1], a fast algorithm that minimizing cost function designed for block input signal is employed, while in [2], a novel cost function that minimizing sample by sample input is used. Although, the two fast algorithm save computational complexities as compared to CMA, the convergence behaviors of the two fast algorithm show different results with repsect to CMA. Thus, in this paper, some analytical results on the error surface of the fast frequency domain CMA are introduced. From the analytical results, we show that the more recent algorithm [2] outperforms the previous algorithm [1]. Simulation results reveals that the recent algorithm [2] shows 50% enhanced convergence with respect to the old fast algorithm [1]. Also, we show that the recent fast algorithm [2] has comparable convergence performance with respect to conventional CMA algorithm.

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Pre-Service Teachers' Understanding of Radian (예비교사의 라디안에 대한 이해)

  • Kang, Hyangim;Choi, Eun Ah
    • School Mathematics
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    • v.17 no.2
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    • pp.309-329
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    • 2015
  • This study is to provide didactical implications for teaching and learning of radian through a analysis of investigation result about pre-service teachers' understanding of radian. The results of this study are as follows. First, pre-service teachers understood the radian as ${\frac{180^{\circ}}{\pi}}$, rather than as the definition. Secondly, the definition style of radian affected the problem solving strategy for the measurement of the angle. Thirdly, pre-service teachers had insufficient content knowledge about properties of measurement as a pure number of radian. Lastly, They failed to describe the usefulness of circular measure. We suggested the definition of radian in textbooks should be changed from ${\frac{180^{\circ}}{\pi}}$ to mathematical definition of radian. And the general angle should be stated as the reason why the domain of trigonometric function is real numbers.

Multiobjective Genetic Algorithm for Design of an Bicriteria Network Topology (이중구속 통신망 설계를 위한 다목적 유전 알고리즘)

  • Kim, Dong-Il;Kwon, Key-Ho
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.39 no.4
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    • pp.10-18
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    • 2002
  • Network topology design is a multiobjective problem with various design components. The components such as cost, message delay and reliability are important to gain the best performance. Recently, Genetic Algorithms(GAs) have been widely used as an optimization method for real-world problems such as combinatorial optimization, network topology design, and so on. This paper proposed a method of Multi-objective GA for Design of the network topology which is to minimize connection cost and message delay time. A common difficulty in multiobjective optimization is the existence of an objective conflict. We used the prufer number and cluster string for encoding, parato elimination method and niche-formation method for the fitness sharing method, and reformation elitism for the prevention of pre-convergence. From the simulation, the proposed method shows that the better candidates of network architecture can be found.

Delamination Analysis of Orthotropic Laminated Plates Using Moving Nodal Modes (이동절점모드를 사용한 직교이방성 적층평판의 층간분리해석)

  • Ahn, Jae-Seok
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.4
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    • pp.293-300
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    • 2012
  • In this study, the delamination analysis has been implemented to investigate the initiation and propagation of crack in composite laminates composed of orthotropic materials. A simple modeling was achieved by moving nodal technique without re-meshing work when crack propagation occurred. This paper aims at achieving two specific objectives. The first is to suggest a very simple modeling scheme compared with those applied to conventional h-FEM based models. To verify the performance of the proposed model, analysis of double cantilever beams with composite materials was implemented and then the results were compared with reference values in literatures. The second one is to investigate the behavior of interior delamination problems using the proposed model. To complete these objectives, the full-discrete-layer model based on Lobatto shape functions was considered and energy release rates were calculated using three-dimensional VCCT(virtual crack closure technique) based on linear elastic fracture mechanics.

Network Management System Architecture for Enhanced Network Survivability (생존성 향상을 위한 네트워크 관리 시스템의 구조)

  • Lee, Jung-Su;Kim, Nam-Hun;Jo, Pyeong-Dong;Lee, Yeong-Hui
    • Journal of KIISE:Information Networking
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    • v.27 no.4
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    • pp.498-506
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    • 2000
  • 네트워크 관리 시스템은 네트워크를 모니터링하고 감독하여 잘 유지하고 활용성을 높이는 것을 목적으로 하는 시스템이다. 네트워크 관리 시스템 자체의 생존성이 보장되지 않으면 네트워크를 안정한 상태로 유지하는 것은 매우 어렵다. 본 논문에서는 네트워크 관리 시스테 자체의 생존성을 높일수 있도록 매니저들간의 세션을 형성하고 SNA를 통해 고장이 발생한 매니저의 관리 작업을 세션 내의 다른 매니저들이 대행해 주도록 하여 네트워크가 항상 관리될수 있도록 하는 방법을 제안하였다. 제안한 방법은 하나의 관리 스테이션에 집중되던 부하를 하위의 매니저들에게 분산시키고 SNMP 메시지를 전송하기 위해 백본을 통과하는 트래픽을 줄일 수 있다. 제안한 방법의 우수성을 보이기 위해 노드의 오류에 관한 생존성 함수를 도출하였고 그에 따른 분석결과를 도시하였다

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The Multi-objective Optimization of Switched Reluctance Motor (스위치드 릴럭턴스 전동기의 다중목적함수의 최적화 방법 연구)

  • Choi, Jae-Hak;Shin, Hyun-Hun;Lim, Jin-Jae;Lee, Ju;Lee, Jung-Ho;Baek, Soo-Hyun
    • Proceedings of the KIEE Conference
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    • 2002.11d
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    • pp.118-120
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    • 2002
  • In this paper, a multi-object optimization based on a progressive quadratic response surface method (PQRSM) and a time stepping finite element method (FEM) is proposed. The new PQRSM and FEM are able to decide optimal geometric and electric variables of the switched reluctance motor (SRM) with two objective functions: torque ripple minimization and average torque maximization. The result of the optimum design for SRM show an improved performance of motor and a relationship between torque ripple and average torque.

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Optimal Shape Design of Dual Reflector Antenna Based on Genetic Algorithm (유전 알고리즘 기반의 이중 반사경 안테나 형상최적화 기법)

  • Park, Jung-Geun;Chung, Young-Seek;Kang, Won-June;Shin, Jin-Woo;So, Joon-Ho;Cheon, Chang-Yul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.5
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    • pp.445-454
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    • 2015
  • In this paper, we propose an optimal design method for a dual reflector antenna(DRA) using the Genetic algorithm. In order to reduce the computational burden during the optimal design, we exploit the iterative physical optics(IPO) to calculate the surface current distribution at each reflector antenna. To improve the accuracy, we consider the shadow effect by the structure and the coupling effect by the multi-reflection based on the iterative MFIE(Magnetic Field Integral Equation). To reduce the number of design variables and generate a smooth surface, we use the Bezier function with the control points, which become the design variables in this paper. We adopt the HPBW(Half Power Beam Width), the FNBW(First Null Beam Width), and the SLL(Side Lobe Level) as the objective or cost functions. To verify the results, we compare them with the those of the commercial tool.

Transit Frequency Optimization with Variable Demand Considering Transfer Delay (환승지체 및 가변수요를 고려한 대중교통 운행빈도 모형 개발)

  • Yu, Gyeong-Sang;Kim, Dong-Gyu;Jeon, Gyeong-Su
    • Journal of Korean Society of Transportation
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    • v.27 no.6
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    • pp.147-156
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    • 2009
  • We present a methodology for modeling and solving the transit frequency design problem with variable demand. The problem is described as a bi-level model based on a non-cooperative Stackelberg game. The upper-level operator problem is formulated as a non-linear optimization model to minimize net cost, which includes operating cost, travel cost and revenue, with fleet size and frequency constraints. The lower-level user problem is formulated as a capacity-constrained stochastic user equilibrium assignment model with variable demand, considering transfer delay between transit lines. An efficient algorithm is also presented for solving the proposed model. The upper-level model is solved by a gradient projection method, and the lower-level model is solved by an existing iterative balancing method. An application of the proposed model and algorithm is presented using a small test network. The results of this application show that the proposed algorithm converges well to an optimal point. The methodology of this study is expected to contribute to form a theoretical basis for diagnosing the problems of current transit systems and for improving its operational efficiency to increase the demand as well as the level of service.

Reliability Based Design Optimization for the Pressure Recovery of Supersonic Double-Wedge Inlet (이중 쐐기형 초음속 흡입구의 압력회복률에 대한 신뢰성 기반 최적설계)

  • Lee, Chang-Hyuck;Ahn, Joong-Ki;Bae, Hyo-Gil;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.11
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    • pp.1067-1074
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    • 2010
  • In this study, RBDO(Reliability Based Design Optimization) was performed for a supersonic double-wedge inlet. By considering uncertainty of design with given design space, the pressure recovery was transformed into the probabilistic constraint while the inlet drag was considered as a deterministic objective function. To save computational analysis cost and to search good design space, Latin-Hypercube design of experiment and the Kriging model were incorporated and then RBDO was performed. Monte-Carlo simulation was performed to verify the accuracy of AFORM(Advanced First Order Reliability Method). It was found that AFORM result agreed very well with the Monte-Carlo simulation result. The system reliability was guaranteed by considering uncertainty of the design variables. In case of considering diverse uncertainty of system design, RBDO was found to be useful.

A VSMFC Controller Design of Robot Manipulators Using Computed Torque Method (CTM을 위한 로보트 매니퓰레이터의 VSMFC 제어기 설계)

  • Park, Sei-Seung;Park, Chong-Kug
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.10
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    • pp.53-59
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    • 1990
  • In the control of robot manipulators, this paper presents a design of a new variable structure model following controller(VSMFC) using computed torque method (CTM). A sufficient condition for the existence of a sliding mode is derived by Lyapunov function. The reference model is a double integrators and the acceleration input consists of a proportional-derivative controller for the purpose of the stabilization of system and the desired performance. The proposed control scheme which consists of upper bounded and estimated value of each term of the manipulator of matrix inversion. Therefore the simulation results show that this controller is improved to the convergence of desired trajectories.

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