• 한국정밀공학회지
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• 제26권8호
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• pp.62-71
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• 2009

In mobile robotics, ultrasonic sensors became one of the most popular devices for collision avoidance and navigation primarily due to data robustness, the easy availability of low-cost systems, their compact size, simple circuits, and their ease in interfacing with computers. However, ultrasonic sonic sensors are subject to noise which results in inaccuracy of mapping and localization of the robot. This paper introduces a new approach to enhance environmental maps based on ultrasonic range data using linear interpolation and Newton interpolation. The simulation and experimental results show that the proposed method improves of the accuracy of the map through better distance estimation between the mobile robot and obstacles.

• 대한기계학회논문집
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• 제19권2호
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• pp.433-442
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• 1995

For the line search of a multi-variable optimization, an efficient algorithm is presented. The algorithm sequentially employs several polynomial approximations such as 2-point quadratic interpolation, 3-point cubic interpolation/extrapolation and 4-point cubic interpolation/extrapolation. The order of polynomial function is automatically increased for improving the accuracy of approximation. The method of approximation (interpolation or extrapolation) is automatically switched by checking the slope information of the sample points. Also, for selecting the initial step length along the descent vector, a new approach is presented. The performance of the proposed method is examined by solving typical test problems such as mathematical problems, mechanical design problems and dynamic response problems.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권6호
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• pp.235-240
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• 2002

This paper presents a new method for estimating the block pulse series coefficients by using the Lagrange's second order interpolation polynomial. Block pulse functions have been used in a variety of fields such as the analysis and controller design of the systems. When the block pulse functions are used, it is necessary to find the more exact value of the block pulse series coefficients. But these coefficients have been estimated by the mean of the adjacent discrete values, and the result is not sufficient when the values are changing extremely. In this paper, the method for improving the accuracy of the block pulse series coefficients by using the Lagrange's second order interpolation polynomial is presented.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.135-140
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• 2007

In this paper, an Improved Dimension Reduction(IDR) method is proposed for uncertainty quantification that employes Kriging interpolation technic. It has been acknowledged that the DR method is accurate and efficient for assessing statistical moments and reliability due to the sensitivity free feature. However, the DR method has a number of drawbacks such as instability and inaccuracy for problems with increased nonlineality. In this paper, improved DR is implanted by three steps. First, the Kriging interpolation method is used to accurately approximate the responses. Second, 2N+1 and 4N+1 ADOEs are proposed to maintain high accuracy of the method for UQ analysis. Third, numerical integration scheme is used with accurate but free response values at any set of integration points of the surrogated model.

• 환경영향평가
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• 제21권1호
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• pp.219-227
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• 2012

Daily solar radiation is essential for water resources planning and environmental impact assessment. However, radiation data is not commonly available in Korea other than in big cities, and there has been no direct measurement for rural areas where water resources planning and environmental impact assessment is usually most needed. In general, missing radiation data is estimated from nearby regional stations within a certain distance, and this study compared two dominant methods (modified Angstrom equation and transmittance interpolation method) at six stations in Nakdong River watershed area. Two methods shows a similar level of accuracy but the transmittance interpolation method is likely to be superior in that there is no need for any measurement element since the modified Angstrom equation require the sunshine hour measurement. This study will contribute to improve water resource and water quality management in Nakdong River watershed.

• 한국멀티미디어학회논문지
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• 제17권10호
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• pp.1150-1159
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• 2014

This paper proposes a method for extracting tissue cells from an organism image by an electron microscope and getting the whole cell number and the area from the cell. In general, the difference between the cell color and the background is used to extract tissue cell. However, there may be a problem when overlapped cells are seen as a single cell. To solve the problem, we split them by using cell size and curvature. This method has a 99% accuracy rate. To measure the cell area, we compute two areas, the inside and boundary of the cell. The inside is simply calculated by the number of pixels. The cell boundary is obtained by applying super sampling, linear interpolation, and cubic spline interpolation. It improves the error rate, 18%, 19%, and 120% respectively, in comparison to the counting method that counts a pixel area as 1.

• Spatial Information Research
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• 제14권1호
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• pp.29-41
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• 2006

공간통계자료는 비록 공간상 모든 위치에 그 값이 존재하나, 실제 우리는 모든 지점에서 공간자료를 수집하지 못한다. 따라서 몇 개의 대표 지점에서 자료를 수집한 후 이를 미관측 지역까지 확장하여 사용하게 되는데, 이때 공간보간 기법이 적용된다. 본 논문에서는 다양한 분야에서 매우 중요하게 사용되는 강우자료에 대해 공간보간을 실시하고 그 정확성을 검증하였다. 기상청에서 운영하는 총 373 개의 강우관측소의 2004 년도 연 총강우량에 대해 공간보간을 실시하였으며, 그로부터 이론적 베리오그램으로 가우시안 함수를 사용한 일반 크리깅이 가장 높은 정확성을 보인 것으로 확인되었다. 다른 보간기법에 비해 크리깅 기법은 비교적 정확성이 높은 것으로 분석되었으며, 결과에 있어서는 예측값의 분포 범위가 좁은 일반화의 특성을 갖는 것으로 나타났다. 지역경향면 분석(local trend surface analysis), IDW, RBF의 경우 강우자료에 대한 예측값의 범위가 크리깅에 비해 매우 넓게 분포하는 것으로 나타났으며, 공간적으로는 인접한 지역의 예측값이 크리깅에 비해 급변하는 것으로 분석되었다.

• 디지털융복합연구
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• 제13권9호
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• pp.209-218
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• 2015

디지털 전산모사(computer simulation)는 모든 융합기술 분야에서 실험을 통한 이론 정립에 중요한 역할을 담당하고 있으며, 보간법은 격자위에서의 알고 있는 값을 이용하여 모르는 값을 알아내는 방법론이다. 그러므로 보간법의 선택은 디지털 전산모사에서 아주 중요한 문제이다. 본 논문에서는 디지털 전산모사 작업에서 사용되는 6종류의 보간법(Quartic-Lagrangian, Cubic Spline, Fourier, Hermite, PWENO, SL-WENO)의 성능을 비교, 평가한다. 디지털 전산모사의 선형 이류 방정식을 각 방법에 적용함으로써 장단점을 분석하였다. 각 방법론의 성능을 비교하기 위하여, 정확도 계산과 오차 함수를 도입한다. 정확도의 계산은 잘 알고 있는 $L^1-norm$ 계산, 분산 계산, 소멸 오차 그리고 전체적인 오차를 시행한다. 고차의 방법론이 효과적이기는 하나 진동 등 기타의 요인이 발생한다.

• Structural Engineering and Mechanics
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• 제51권6호
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• pp.923-937
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• 2014

The rational finite element method is different from the standard finite element method, which is constructed using basic solutions of the governing differential equations as interpolation functions in the elements. Therefore, it is superior to the isoparametric approach because of its obvious physical meaning and accuracy; it has successfully been applied to the isotropic elasticity problem. In this paper, the formulation of rational finite elements for plane orthotropic elasticity problems is deduced. This method is formulated directly in the physical domain with full consideration of the requirements of the patch test. Based on the number of element nodes and the interpolation functions, different approaches are applied with complete polynomial interpolation functions. Then, two special stiffness matrixes of elements with four and five nodes are deduced as a representative application. In addition, some typical numerical examples are considered to evaluate the performance of the elements. The numerical results demonstrate that the present method has a high level of accuracy and is an effective technique for solving plane orthotropic elasticity problems.

• 한국산학기술학회논문지
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• 제7권4호
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• pp.690-696
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• 2006

본 연구는 연구논제[1]에서 제안한 보정방법을 평창강 지역 11개 강우관측소를 대상으로 적용하였다. 또한 본 연구는 방법별 오차범위 및 주변관측소 개수에 따른 공간적 분포 영향을 분석하였다. 연구 적용 결과 선형계획법이 가장 작은 오차를 나타내었으나 계산을 위한 프로그램이 필요하므로 현장의 실무적용에는 어려움이 있는 것으로 나타났다. 역거리법은 선형계획법과 비교해서 비교적 간단하고 정확한 결과를 보이는 것으로 나타났다. 따라서, 본 연구결과는 강우량 보정의 정확도를 높이는데 기여할 수 있을 것으로 판단된다.