• 전기학회논문지
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• 제56권2호
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• pp.428-431
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• 2007

A floating-point number system is used to represent a wide range of real numbers using finite number of bits. The standard the IEEE adopted in 1987 divides the range of real numbers into intervals of [$2^E,2^{E+1}$), where E is an Integer represented with finite bits, and defines equally spaced equal counts of discrete numbers in each interval. Since the numbers are defined discretely, not only the number representation itself includes errors but in floating-point arithmetic some strange behaviors are observed which cannot be agreed with the real world arithmetic. In this paper errors with floating-point number representation, those with arithmetic operations, and those due to order of arithmetic operations are analyzed theoretically with help of and verification with the results of some MATLAB program executions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2557-2561
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• 2005

The PID controller design and choosing PID parameters according to system response are proposed in this paper. Here PID controller is employed to control DC motor speed and Matlab program is used for calculation and simulation. Choosing PID parameters are demonstrated by several contrast experiments and a way for setting PID parameters values is discussed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.423-426
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• 2002

This paper presents a new analytical representation and simulation of the phase inductance of a Switched Reluctance Motor(SRM) using Matlab/M-file. This simulation method has many advantages: it is free from expression, can be applied widely, demonstrates inductance profile using motor parameter only, and save run time. Moreover, this simulation method can be easily realize various SRM model unlikely the existing method that limited itself to one model. And analytical expression for inductance profile is welcome as it allows for easier analysis of the motor, for it can bring insight in it working, in formulating control strategies and in achieving high accuracy in performance computations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.512-514
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• 2002

The dynamic permittivity of a microstrip structure leads to a convenient and modified Smith-chart representation that includes the frequency-dependent influence of the lossy characteristics of the line cohesively. The efficacy of the model is illustrated with an example concerning a microstrip patch antenna. Relevant simulations show that the input impedances calculated from the model are more accurate than those from the previous model in the literature by comparing to the measure results, as illustrated with an example of a patch antenna. This model is compatible for CAD efforts with MATLAB$\^$TM/ facilitation fast and user-friendly implementations.

• 조명전기설비학회논문지
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• 제14권3호
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• pp.88-96
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• 2000

순시전력이론은 수학적으로 이해가 용이하며, PWM 전력변환기를 $\alpha$-$\beta$ 정지 좌표에서 비교적 쉽게 제어할 수 있기 때문에 많은 연구가 되어 오고 있다. 그런데 순시진력이론은 보상기준전류 계산과정에 없어서 많은 전류 성분과 전력성분이 얻어지며 이는 순시전력이론의 불리적인 해석에 영향을 주고 있다. 특히 순시전력이론올 처음 접하는 초보 연구자들은 이와 같은 순시전력의 직류 및 교류성분 그리고 순시전류획 $\alpha$-$\beta$정분의 표준 파형에 대한 정보가 부족하기 때문에 각 성분들의 계산이 맞는지 확인하기 어려웠다. 따라서 본 연구에서는 MATLAB/SIMULINK에 의하여 순시전력이론의 전류성분파 전력성분올 파형과 $\alpha$-$\beta$공간궤적으로 나타내어 초보 연구자들의 이해를 돕도록 하였다. 또한 순시전력 성분 보상애 따른 보상기준 전류 파형이 비선형 부하 계통의 전원전류 파형에 미치는 영향을 쉽게 파악할 수 있도록 하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.412-417
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• 2008

In a traditional topology optimization method, material properties are usually distributed by finite element density and visualized by a gray level image. The distribution method based on element density is adequate for a great mass of 2-D topology optimization problems. However, when it is used for 3-D topology optimization, it is always difficult to obtain a smooth model representation, and easily appears a virtualconnect phenomenon especially in a low-density domain. The 3-D structural topology optimization method has been developed using the node density instead of the element density that is based on SIMP (solid isotropic microstructure with penalization) algorithm. A computer code based on Matlab was written to validate the proposed method. When it was compared to the element density as design variable, this method could get a more uniform density distribution. To show the usefulness of this method, several typical examples of structure topology optimization are presented.

• Structural Engineering and Mechanics
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• 제57권1호
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• pp.65-89
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• 2016

This paper presents the development of methodologies using Extended Finite Element Method (XFEM) for cracked unstiffened and concentric stiffened panels subjected to constant amplitude tensile fatigue loading. XFEM formulations such as level set representation of crack, element stiffness matrix formulation and numerical integration are presented and implemented in MATLAB software. Stiffeners of the stiffened panels are modelled using truss elements such that nodes of the panel and nodes of the stiffener coincide. Stress Intensity Factor (SIF) is computed from the solutions of XFEM using domain form of interaction integral. Paris's crack growth law is used to compute the number of fatigue cycles up to failure. Numerical investigations are carried out to model the crack growth, estimate the remaining life and generate damage tolerant curves. From the studies, it is observed that (i) there is a considerable increase in fatigue life of stiffened panels compared to unstiffened panels and (ii) as the external applied stress is decreasing number of fatigue life cycles taken by the component is increasing.

• 한국전산구조공학회논문집
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• 제30권2호
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• pp.153-158
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• 2017

본 논문에서는 재료 탄성계수의 공간적 불확실성을 고려한 위상최적화 문제를 다루었다. 88줄로 작성된 MATLAB Code를 사용하여 MBB(messerschmidt-$b{\ddot{o}}lkow$-blohm) model에 대해 5,000개의 추계장 표본을 작성하여 해석에 사용하였다. 재료탄성계수의 추계장 표본은 스펙트럼 모사법을 적용하여 작성하였고, 구조계영역 내에서 정규분포하는 것으로 가정하였다. 해석결과에 대한 통계처리를 통하여 형상최적화의 결과를 나타내는 체적률의 변화도를 추계장의 상관거리에 대하여 나타내었다. 최적형상의 변화도는 상관거리가 작을 경우 크게 산정되었고, 상관거리가 큰 경우에는 적은 값을 나타내었다. 큰 상관거리에서 변화도가 적은 것은 위상최적화가 선형해석에 따르기 때문이다. 따라서 위상최적화 시 구조재료 불확실성의 특성에 따른 고려가 필요한 것으로 사료된다.

• 한국초전도ㆍ저온공학회논문지
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• 제18권4호
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• pp.40-43
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• 2016

Beam trajectory is needed to be controlled in heavy ion accelerator system. Quadruple magnets are widely used in heavy ion accelerator for focusing the transporting particles. A quadruple triplet system which consists of three consecutive quadrupoles, Q1, Q2 and Q3, is used to control beam trajectory at a focused position. Q1 and Q3 have symmetry with respect to Q2. The beam trajectory in magnet system is affected by higher order fields existed in real fields. For quadrupoles, the representation simulation of beam trajectory was carried out to study the beam trajectory and to estimate an effect of higher order field in triplet system. SCALA program was used to simulate the beam trajectory in $Opera^{TM}$. SCALA can analyze a large number of beam trajectories at the same time by adjusting the size of finite element of the emitter. With $Opera^{TM}$ and $Matlab^{TM}$ programs, the position of focused beam spot in quadruple triplet system can be increased or decreased using evolution strategy (ES) method, therefore the length of triplet system can be controlled. Finally, the quadruple triplet system with the appropriate length and expected beam spot range was suggested in this paper.

• Structural Engineering and Mechanics
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• 제72권1호
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• pp.31-41
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• 2019

Structural integrity assessment of piping components is of paramount important for remaining life prediction, residual strength evaluation and for in-service inspection planning. For accurate prediction of these, a reliable fracture parameter is essential. One of the fracture parameters is stress intensity factor (SIF), which is generally preferred for high strength materials, can be evaluated by using linear elastic fracture mechanics principles. To employ available analytical and numerical procedures for fracture analysis of piping components, it takes considerable amount of time and effort. In view of this, an alternative approach to analytical and finite element analysis, a model based on relevance vector machine (RVM) is developed to predict SIF of part through crack of a piping component under fatigue loading. RVM is based on probabilistic approach and regression and it is established based on Bayesian formulation of a linear model with an appropriate prior that results in a sparse representation. Model for SIF prediction is developed by using MATLAB software wherein 70% of the data has been used for the development of RVM model and rest of the data is used for validation. The predicted SIF is found to be in good agreement with the corresponding analytical solution, and can be used for damage tolerant analysis of structural components.