• Nuclear Engineering and Technology
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• 제49권3호
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• pp.484-494
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• 2017

In industrial plants such as nuclear power plants, system operations are performed by embedded controllers orchestrated by Supervisory Control and Data Acquisition (SCADA) software. A targeted attack (also termed a control aware attack) on the controller/SCADA software can lead a control system to operate in an unsafe mode or sometimes to complete shutdown of the plant. Such malware attacks can result in tremendous cost to the organization for recovery, cleanup, and maintenance activity. SCADA systems in operational mode generate huge log files. These files are useful in analysis of the plant behavior and diagnostics during an ongoing attack. However, they are bulky and difficult for manual inspection. Data mining techniques such as least squares approximation and computational methods can be used in the analysis of logs and to take proactive actions when required. This paper explores methodologies and algorithms so as to develop an effective monitoring scheme against control aware cyber attacks. It also explains soft computation techniques such as the computational geometric method and least squares approximation that can be effective in monitor design. This paper provides insights into diagnostic monitoring of its effectiveness by attack simulations on a four-tank model and using computation techniques to diagnose it. Cyber security of instrumentation and control systems used in nuclear power plants is of paramount importance and hence could be a possible target of such applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.994-996
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• 2003

The Response Surface Methodology is frequently used for building an approximation model. However, its approximation errors often occur in engineering problem, because of the use of the Least Square Method. Therefore, this paper introduces the Moving Least Square Method to obtain the more accurate Response Surface Model, and then the detent force of a Permanent Magnet Linear Synchronous Motor is applied to verify the accuracy of the introduced method.

• 한국전산구조공학회논문집
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• 제27권3호
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• pp.183-189
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• 2014

본 연구에서는 다면체 요소의 개발을 위하여 Wachspress 좌표계와 이동최소자승 근사를 기반으로하는 형상함수와 수치적분 방법을 제시하고 있다. 사면체 요소를 사면체 영역으로 분할하여 형상함수가 구성이 되고 이 영역을 사용한 일관성있는 수치적분이 수행되게 된다. 다면체 요소 면에서 Wachspress 좌표계를 사용하고 요소 내부에서 라플라스 방정식을 적용하여 이동최소자승 근사의 가중함수를 정의하게 된다. 본 연구에서 개발되는 다면체 요소의 형상함수와 수치적분 방법은 일반적인 유한요소와 유사한 특성을 갖게 되는데 수치 예제를 통하여 유효성을 보여주었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.599-603
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• 2002

We propose a new meshfree method to be called the fast moving least square reproducing kernel collocation method(FCM). This methodology is composed of the fast moving least square reproducing kernel(FMLSRK) approximation and the point collocation scheme. Using point collocation makes the meshfree method really come true. In this paper, FCM Is shown to be a good method at least to calculate the numerical solutions governed by second order elliptic partial differential equations with geometric singularity or geometric multi-scales. To treat such problems, we use the concept of variable dilation parameter.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.567-574
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• 2006

We present applications of MLS-based finite elements, which enable us to easily treat highly complex nonmatching finite element meshes and discontinuities. The shape functions of MLS-based finite element can be easily generated with the aid of Moving Least Square approximation on the parental domain. The major advantage includes that the position of element nodes as well as the number of the element nodes can be conveniently adjusted according to the nature of the problems under consideration, so that finite-element mesh is straightforwardly adapted to evolving discontinuities and. interfaces. Furthermore, we show that the present MLS-based finite elements are efficiently applied for elastic-plastic deformations, wherein the implicit constraint of incompressibility should be properly handled.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.679-682
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• 1988

From the viewpoint of general recognition system, B-spline is introduced for the approximation and recognition of human profile contours. Profile contour is approximated to the cublic B-spline curve by least square fitting so that B-Spline nodes nearly correspond with the curvature extrema of the contour. This method is designed for the spline to be good features in recognition, and also showed good approximation compared with the variants of B-spline appraximation.

• 정보처리학회논문지B
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• 제9B권2호
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• pp.223-230
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• 2002

유성음원과 무성음원을 사용하는 음성부호화 방식에 있어서, 같은 프레임 안에 모음과 무성자음이 있는 경우에 음성 파형에 일그러짐이 나타난다. 본 논문에서는 최소 자승법을 적용한 새로운 TSIVUC 근사합성법을 제시하였다. 이 방법에서 TSlUVC의 추출에는 zero crossing rate과 FIR-STREAK 필터의 잔차신호를 이용한 개별피치 추출 알고리즘을 사용하였다. 실험결과, 최소 자승법을 적용하여 양호한 TSIUVC 근사합성 파형을 얻을 수 있었다. 또한 최대 오타신호에 있어서의 주파수 신호가 일그러짐이 적은 근사합성 파형에 중요한 역할을 한다는 것이다. 이 방법은 음성합성, 음성분석, 새로운 Voiced/Silence/TSIUVC의 음성부호화 방식에 활용할 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1175-1179
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• 2006

유성음원과 무성음원을 사용하는 음성부호화 방식에 있어서, 프레임 안에 모음과 무성자음이 있는 경우에 음성 파형에 일그러짐이 나타난다. 본 논문에서는 LMS를 적용한 새로운 TSIUVC 근사합성법을 제시하였다. 실험결과, LMS를 적용하여 양호한 TSRIVC 근사합성 파형을 얻을 수 있었으며, 오차신호가 일그러짐이 적은 근사합성 파형에 중요한 역할을 한다는 것을 알 수 있었다. 이 방법은 음성합성, 음성분석, 새로운 Voiced/Silence/TSIUVC의 음성부호화 방식에 활용할 수 있을 것으로 기대된다.

• International Journal of Automotive Technology
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• 제8권1호
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• pp.93-102
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• 2007

The frontal crash optimization of an engine room member using the response surface method was studied. The engine room member is composed of the front side member and the sub-frame. The thicknesses of the panels on the front side member and the sub-frame were selected as the design variables. The purpose of the optimization was to reduce the weight of the structure, under the constraint that the objective quantity of crash energy is absorbed. The response surface method was used to approximate the crash behavior in mathematical form for optimization procedure. To research the effect of the regression method, two different methodologies were used in constructing the response surface model, the least square method and the moving least square method. The optimum with the two methods was verified by the simulation result. The precision of the surrogate model affected the optimal design. The moving least square method showed better approximation than the least square method. In addition to the deterministic optimization, the reliability-based design optimization using the response surface method was executed to examine the effect of uncertainties in design variables. The requirement for reliability made the optimal structure be heavier than the result of the deterministic optimization. Compared with the deterministic optimum, the optimal design using the reliability-based design optimization showed higher crash energy absorption and little probability of failure in achieving the objective.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권4호
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• pp.180-183
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• 2004

This paper presents a description of the point collocation method and its application to the electromagnetic field computation. The interpolation scheme is based on the fast moving least square reproducing kernel approximation. In the method, the integration cell is not required and the essential boundary conditions can be enforced directly. Numerical simulations on 1-D and 2-D problems are carried out to validate the method. It is found that computational efficiency is higher than the general mesh-free methods.