• Kyungpook Mathematical Journal
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• 제48권4호
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• pp.665-684
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• 2008

Runge-Kutta-Nystr$\"{o}$m (RKN) methods provide a popular way to solve the initial value problem (IVP) for a system of ordinary differential equations (ODEs). Users of software are typically asked to specify a tolerance ${\delta}$, that indicates in somewhat vague sense, the level of accuracy required. It is clearly important to understand the precise effect of changing ${\delta}$, and to derive the strongest possible results about the behaviour of the global error that will not have regular behaviour unless an appropriate stepsize selection formula and standard error control policy are used. Faced with this situation sufficient conditions on an algorithm that guarantee such behaviour for the global error to be asympotatically linear in ${\delta}$ as ${\delta}{\rightarrow}0$, that were first derived by Stetter. Here we extend the analysis to cover a certain class of ODEs with low-order derivative discontinuities, and the class of ODEs with constant delays. We show that standard error control techniques will be successful if discontinuities are handled correctly and delay terms are calculated with sufficient accurate interpolants. It is perhaps surprising that several delay ODE algorithms that have been proposed do not use sufficiently accurate interpolants to guarantee asymptotic proportionality. Our theoretical results are illustrated numerically.

• 대한공간정보학회지
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• 제18권2호
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• pp.93-97
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• 2010

본 연구에서는 카메라 자세 정보가 없는 무인헬기에 탑재된 카메라로부터 취득된 연속영상을 등록하기 위한 개량형 KLT기법을 제시하였으며 그 절차는 다음과 같이 구성된다. 초기 특징점은 연속영상에서 모서리점을 검출하고 동적프로그래밍에 의한 특성곡선매칭에 의해 특징점을 추적하였다. 추적된 특징점 중 오류점은 RANSAC추정법에 의해 제거되며 호모그래피이론에 의해 나머지점은 정확한 정합점으로 분류되었다. 영상등록에 의한 편위보정영상모자이크생성은 쌍일차보간법에 의해 생성하였으며, 결과분석을 통해 제시된 방법이 흔들림이 있는 연속영상을 등록하는데 적합한 방법임을 제시하였다.

• 대한공간정보학회지
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• 제17권1호
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• pp.71-78
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• 2009

GPS/INS를 이용한 항공사진측량의 경우 GPS 이동측위를 위해 촬영지역에 GPS 지상기준국의 설치가 필수적이다. 하지만 항공사진측량을 위한 지상기준국의 설치는 여러 가지 제한 요소들로 인해 현실적으로 어려운 경우가 많다. 이러한 문제점을 해결하기 위해 본 연구에서는 상시관측소 자료를 이동측위에 이용하여도 충분한 정확도를 확보할 수 있는 지를 분석하였다. 30초 간격으로 저장되어 있는 상시관측소 자료의 내삽을 통해 결정한 외부표정요소와 촬영지역에서 수신된 지상기준국 자료로부터 결정한 외부표정요소를 GPS/INS 항공삼각측량에 각각 적용한 후 정확도를 비교하였다. 그 결과 상시관측소 자료로 지상기준국 자료를 대체하여 사용하여도 충분한 정확도를 얻을 수 있었다.

• 한국통신학회논문지
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• 제36권12C호
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• pp.738-743
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• 2011

고해상도 3차원 깊이 영상은 고품질의 3차원 방송을 위해 필요한 중요한 정보이다. 깊이 카메라는 정확한 깊이 정보를 실시간으로 얻을 수 있지만, 카메라 물리적 한계로 인해 저해상도의 깊이 영상만 이용한다. 본 논문에서는 저해상도의 깊이 영상과 색상 영상을 이용하여 색상 영상을 보간 하는 방법을 제안한다. 제안하는 방법은 랜덤워크 확률 모델을 이용하여 각 화소들이 초기 깊이값과 같을 확률값을 정의하여 가장 높은 확률을 가지는 초기 깊이값을 나머지 화소들에 복사한다. 제안한 방법은 인접한 화소들만을 이용하는 것이 아니라 경로를 따라 비용을 계산함으로써, 여러 화소에 걸친 색상의 변화율이 고려되어 물체의 경계 주변에서 색상 영역과 깊이 영상간의 경계가 일치하는 향상된 깊이 영상을 얻을 수 있다.

• 대한기계학회논문집
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• 제14권3호
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• pp.646-655
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• 1990

본 연구에서는 EPIES 프로그램의 상세한 내용과 이를 이용한 5가지 파괴역학 시편에 대한 사례 연구에 대하여 보고하고자 한다.

• 전자공학회논문지A
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• 제30A권3호
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• pp.76-87
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• 1993

We present a self-consistent, 2-dimensional solution of the Poisson and Sch rodinger equation based on the finite difference method with a nonuniform mesh size for a AlGaAs/GaInAs/GaAs HEMT devide. During the interative self-consistent calculation, however, we calculate Schrodinger equation only a some region of device, not a fully region in order to save the moemory and the speed-up of computation, and then use the approximated data for the other region using by a interpolation method with a given values. Also we adopt the proper matrix transformation method that allows preservation of the symmetric, form of the discretized Schrodinger equation, even with the use of a nonumiform mesh size, therefor, can reduce the computation time. We calculate the wavefunction, eigenstates and the electron concentration uat channel layer nder the thermal equilibrium and the biased conditions, respectively. Also,these parameters are used to solve 2-dimensional tdistribution of potential in he entire region of device. It is proved that the method is very efficient in finding eigenstages extending over relatively large spatial area without loss of accuracy. So, it can be used rather easily in any sarbitrary modulation doped utucture.

• Structural Engineering and Mechanics
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• 제38권2호
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• pp.211-229
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• 2011

In this paper, we present a new explicit procedure using periodic cubic B-spline interpolation polynomials to solve linear and nonlinear dynamic equation of motion governing single degree of freedom (SDOF) systems. In the proposed approach, a straightforward formulation was derived from the approximation of displacement with B-spline basis in a fluent manner. In this way, there is no need to use a special pre-starting procedure to commence solving the problem. Actually, this method lies in the case of conditionally stable methods. A simple step-by-step algorithm is implemented and presented to calculate dynamic response of SDOF systems. The validity and effectiveness of the proposed method is demonstrated with four examples. The results were compared with those from the numerical methods such as Duhamel integration, Linear Acceleration and also Exact method. The comparison shows that the proposed method is a fast and simple procedure with trivial computational effort and acceptable accuracy exactly like the Linear Acceleration method. But its power point is that its time consumption is notably less than the Linear Acceleration method especially in the nonlinear analysis.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.251-254
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• 2006

A precise real-time method of using the IGS ultra rapid products (IGU) and the GPS broadcast ephemeris to calculate the VRS orbit corrections was presented here which was suited for GPS/VRS reference station network based positioning. Test data acquired from both the SGRSN (Sichuan GPS Reference Station Network) and SCIGN (Southern California integrated GPS network) were used to evaluate the performance of the modeling techniques. The new method was proven to be more precise and reliable compared with the existing conventional network-based orbit error interpolation method. It was shown that 0.004ppm relative accuracy was reached, namely the influence from the orbit bias for the RTK positioning within 100km area can be of sub-millimeter level.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.283-287
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• 1996

This paper described the estimator and eliminator far three kinds of artifacts in electrocardiogram. The most efficient estimation of baseline drift could be obtain in the cubic spline interpolation method with the PQ and TP segment which are considered to be isoelectric, from the experimental results obtained from the applied 4 types of algorithms. The time loss and distortion could be avoided with the aid of detection criteria by checking if baseline drifts exist or not. The AIEF proposed in this paper was verified as having the best removal performance with less distortion in the QRS complex through the comparison of 5 proposed algorithms. furthermore, the AIEF are most suitable far the ECG analyzer which was only needed relatively short time data due to the fast conversion into the stable state. The proposed parabolic filter with 11 points width was identified as having the best performance for the elimination of muscle artifacts. Also we could obtain 99.7% detection accuracy of spike component and minimize the error identifying QRS complex as spike.

• 전기학회논문지
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• 제65권7호
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• pp.1144-1150
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• 2016

Short-term load forecasting is essential to the electricity pricing and stable power system operations. The conventional weekday 24-hour load forecasting algorithms consider the temperature model to forecast maximum load and minimum load. But 24-hour load pattern forecasting models do not consider temperature effects, because hourly temperature forecasts were not present until the latest date. Recently, 3 hour temperature forecast is announced, therefore hourly temperature forecasts can be produced by mathematical techniques such as various interpolation methods. In this paper, a new 24-hour load pattern forecasting method is proposed by using similar day search considering the hourly temperature. The proposed method searches similar day input data based on the anomalous weather features such as continuous temperature drop or rise, which can enhance 24-hour load pattern forecasting performance, because it uses the past days having similar hourly temperature features as input data. In order to verify the effectiveness of the proposed method, it was applied to the case study. The case study results show high accuracy of 24-hour load pattern forecasting.