• 대한수학회지
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• 제49권4호
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• pp.703-713
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• 2012

In this paper we study ${\omega}$-limit sets and attraction of non-autonomous discrete dynamical systems. We introduce some basic concepts such as ${\omega}$-limit set and attraction for non-autonomous discrete system. We study fundamental properties of ${\omega}$-limit sets and discuss the relationship between ${\omega}$-limit sets and attraction for non-autonomous discrete dynamical systems.

• Journal of applied mathematics & informatics
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• 제26권1_2호
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• pp.383-387
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• 2008

The problem of recursive filtering for discrete market model with unknown parameters is considered. In this paper, we develop an effective filtering algorithm for discrete market systems with unknown parameters and the error covariance equation determining the accuracy of the proposed algorithm is derived.

• The Journal of the Acoustical Society of Korea
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• 제15권3E호
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• pp.74-77
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• 1996

In this paper we implement the Discrete Rotational Fourier Transform(DRFT) which is a discrete version of the Angular Fourier Transform and its inverse transform. We simplify the computation algorithm in [4], and calculate the complexity of the proposed implementation of the DRFT and the inverse DRFT, in comparison with the complexity of a DFT (Discrete Fourier Transform).

• 대한수학회논문집
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• 제14권4호
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• pp.833-842
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• 1999

In this paper, we construct a fully discrete solution of the incompressible Navier Stokes equations using implicit Runge kutta method. We prove the existence of the fully discrete solution.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.172-172
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• 2000

In this paper, we propose a new discrete-time sliding mode controller for reference tracking. Stability of tracking error is analyzed. Design method of sliding surface for tracking control is proposed. Simulation and experimental results are included to show the effectiveness of the proposed method.

• 한국전자통신학회논문지
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• 제7권4호
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• pp.727-732
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• 2012

본 논문은 DCT, DWT와 역전파 신경망을 이용하여 MIT-BIH 부정맥 데이터베이스의 심전도 신호로부터 정상파와 부정맥 분류를 제안하였다. 역전파 신경망에 사용할 특징입력을 추출하기 위해 첫 번째 단계에서는 DCT 변환을 이용하여 15개의 계수를 선택하였다. 두 번째 단계에서는 DWT 변환 후 각 detail 계수들의 최대값, 최소값, 평균, 분산, 표준편차를 추출하였다. 역전파 신경망은 55개의 특징입력을 이용하여 정상파와 부정맥 파형을 분류하였고, 98.8%의 분류 성능을 나타냈다.

• 한국학교수학회논문집
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• 제6권2호
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• pp.87-99
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• 2003

본 논문에서는 제 7차 교과과정에 의하여 새로운 선택과목으로 선정된 이산수학의 효율적인 교수방안을 논의한다. 이를 위하여 이산수학의 가장 핵심적인 내용인 알고리즘의 개발 필요성 및 목적 등을 강조하기 위하여 행렬 곱셈에 관한 전통적인 방법의 문제점을 분석하며 또한 효율적인 행렬 곱셈 알고리즘을 분석한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.331-336
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• 2005

A lot of manufacturing knowledge and method have applied to increase manufacturing efficiency in industry field. DES(Discrete Event Simulation) is one of solution to deal with manufacturing problems in factory. Beginning of research, old maintenance system of KNR ( Korea National Railroad) and its technical problems are basically investigated. KNR has maintained railway vehicle with their own solution based on experience. Very advanced railway vehicles such as KTX (Korea Train Express) and TTX(Tilting Train Express) will be difficult to maintain with their old maintenance method. In order to apply knowledge of DES, maintenance field of railway must be considered. Imaginary maintenance machine are selected to variable of DES. Maintenance capability of each machine will be evaluated base on imaginary data from imaginary machine. The machine could be very expensive as well as difficult to replace. Target of research is minimization of number of machine in railway workshop. So basic knowledge of discrete event simulation is introduced. Then five essential stages of discrete event simulation are provided. Each maintenance case defined as event. Each event is discrete and simulated base on different case such as one maintenance line with one machine and one maintenance line with two machines in railway workshop. simple maintenance method, discrete event simulation, will be come out very powerful in complicate maintenance system and will be helpful to reduce maintenance cost as well as maintenance labor.

• Structural Engineering and Mechanics
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• 제55권2호
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• pp.315-334
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• 2015

This study's primary aim is to check the existence of a representative volume element for granular materials and determine the link between the properties (responses) of macro structures and the size of the discrete particle assembly used to represent a constitutive relation in a two-scale model. In our two-scale method the boundary value problem on the macro level was solved using finite element method, based on the Cosserat continuum; the macro stresses and modulus were obtained using a solution of discrete particle assemblies at certain element integration points. Meanwhile, discrete particle assemblies were solved using discrete element method under boundary conditions provided by the macro deformation. Our investigations focused largely on the size effects of the discrete particle assembly and the radius of the particle on macro properties, such as deformation stiffness, bearing capacity and the residual strength of the granular structure. According to the numerical results, we suggest fitting formulas linking the values of different macro properties (responses) and size of discrete particle assemblies. In addition, this study also concerns the configuration and displacement fluctuation of discrete particle assemblies on the micro level, accompanied with the evolution of bearing capacity and deformation on the macro level.

• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.71-80
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• 2008

본 연구에서는 조선 공정 계획의 수립 완성도 향상을 위한 다양한 시뮬레이션 시스템의 개발을 지원하는 시뮬레이션 프레임 워크(simulation framework)를 제안하였다. 그리고 제안된 시뮬레이션 프레임워크의 핵심 부분인 시뮬레이션 커널을 구현하였다. 구현된 시뮬레이션 커널은 이산 사건(discrete event)과 이산 시간(discrete time) 시뮬레이션뿐만 아니라 이들이 혼합된 형태의 시뮬레이션도 처리 가능하도록 하였다. 제안된 시뮬레이션 프레임워크의 효율성과 효용성을 평가하기 위해, 이를 조선 분야의 블록 탑재 공정(block erection process)에 적용하였다. 그 결과, 제안된 시뮬레이션 프레임워크가 조선 공정 계획을 위한 다양한 시뮬레이션 시스템을 개발하는데 효과적으로 사용될 수 있음을 확인하였다.