• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.348-353
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• 1996

본 논문은 그 동안 원자력발전소 비상디젤발전기(Emergency Diesel Generator : EDG)의 신뢰도 계산에 사용되어 온 Wyckoff 방법의 문제점을 지적하고, 새롭게 Parametric Empirical Bayes(PEB) 방법의 적용을 제안하고자 한다. Wyckoff 방법은 단순히 성공률을 계산하여 그 값을 EDG의 신뢰도로 간주하고 있어 많은 모순점을 내포하고 있다고 지적되어 오고 있다. Martz에 의해 제안된 PEB 방법은 과거의 경험적 자료를 신뢰도 분석에 이용함으로서 계산된 신뢰도의 정도를 높히는 새로운 계산법이라 할 수 있다. 따라서, 본 논문에서는 국내에서 취득한 EDG 운전자료들을 이용하여 Wyckoff 방법과 PEB 방법에 의한 신뢰도를 계산하고 그 결과를 비교하여 PEB 방법의 효용성을 검토하였다.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.37-38
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• 2017

금속으로 이루어진 긴 선이나 구에 대한 전자파 산란 특성을 계산할 때, 산란 계산 속도를 개선하기 위해 사용하는 고성능 컴퓨팅(HPC) 기반 병렬 처리 특성을 제시한다. 산란 행렬 생성, 가우스 소거법, 산란파 계산 등으로 이루어진 전자파 산란 문제는 병렬 처리를 통해 계산 속도를 높일 수 있다. 산란 문제의 계산 절차를 분석하여 병렬화에 유리한 계산 작업을 분류한 후 OpenMP 기반 병렬화를 적용한다.

• Economic and Environmental Geology
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• v.25 no.1
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• pp.73-77
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• 1992

This paper compares numerical quadrature techniques for computing an inverse Fourier transform integral in two-dimensional resistivity modeling. The quadrature techniques using exponential and cubic spline interpolations are examined for the case of a homogeneous earth model. In both methods the integral over the interval from 0 to ${\lambda}_{min}$, where ${\lambda}_{min}$, is the minimum sampling spatial wavenumber, is calculated by approximating Fourier transformed potentials to a logarithmic function. This scheme greatly reduces the inverse Fourier transform error associated with the logarithmic discontinuity at ${\lambda}=0$. Numrical results show that, if the sampling intervals are adequate, the cubic spline interpolation method is more accurate than the exponential interpolation method.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.33-44
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• 1992

In the present paper, three types of analytic and numerical method are applied to the analysis of sloshing problem. Analytic solution with linear free-surface boundary condition is introduced and numerical methods are used to analyze flued flow trapped in two-and three-dimensional tanks. Source-distribution method is applied to two- and three-dimensional rectangular tanks and sphere tank. Finite difference method is utilized to compute fluid motion and pressure evolution in two dimensional tanks with girders or slopes. Calculated results are compared with those of experiment or other numerical techniques.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.39-44
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• 2006

This paper proposes a method of moments(MoM)/Monte-Carlo simulation and Physical Optics(PO) model to determine Bistatic Coherent Reflectivity of sea surfaces at various wind speeds. For the MoM simulation, a Gaussian random rough sea surface was generated based on the data of Tae-An ocean at various wind speeds and sea surface heights. The numerical results of the MoM/Monte Carlo simulations were used to verify the validity region of the PO model. It was found that the numerical result for a flat surface agrees quite well with the Fresnel reflection coefficient. The validity of the PO model on the rough sea surface is shown by using ray tracing method.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.11-18
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• 2002

In this paper, the method calculating hydroelastic responses of very large floating structure close to a breakwater in waves is presented. The source-dipole distribution method is used to calculate the generalized radiation problem considering breakwater effects and the diffraction problem is analyzed by using the source-dipole distribution andvelocity potential continuation method. The response of a VLFS is approximated by anexpansion in terms of a free-free beam. Calculated model is a VLFS with 1000m in length in a sea with a straight breakwater. The vertical displacements and bonding moments around a VLFS are calculated by variations for distance between a VLFS and a breakwater and incident wave angle to know the effect of a breakwater.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.17-27
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• 2004

A new earthquake design method performing iterative calculations using secant stiffness was developed. The proposed design method has the advantages of convenience and stability in numerical analysis because it uses elastic analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it performs the analysis on the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. Design examples using the proposed method were presented, and its advantages were presented by the comparisons with existing design methods using elastic or inelastic analysis. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer. such as ductility limit on each member, the design concept of strong column - weak beam, and etc. In addition, through iterative calculations on the structure preliminarily designed only with member sizing, the strength and ductility demands of each member can be directly calculated so as to satisfy the given design strategy. As the result. economical and safe design can be achieved.

• Geophysics and Geophysical Exploration
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• v.24 no.4
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• pp.158-163
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• 2021

The frequency-domain induced polarization (IP) response based on Cole-Cole model is expressed as a simple equation in close form. However, it is difficult to compute the time-domain IP response based on Cole-Cole model or any other relaxation model because it cannot be written in closed form. In this study, using numerical experiments, we compared three numerical methods for calculating the time-domain IP response of the Cole-Cole model asymptotically: series expansion, digital linear filtering and Fourier transform. The series expansion method is inadequately accurate for certain time values and converges very slowly. A digital linear filter specially designed to calculate the time-domain IP response does not present the desired accuracy, especially at later times. The Fourier transform method can overcome the abovementioned problems and present the time-domain IP response with adequate accuracy for all time values, even though more computing time is required.

• Journal of Educational Research in Mathematics
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• v.22 no.2
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• pp.293-309
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• 2012

The algorithm of natural number multiplication is one of the basic topics of elementary school mathematics. Mastery of algorithm and understanding of the principles are important educational aims. In this paper we analyzed elementary school mathematics textbooks of South Korea, the United States, Singapore, Japan. As a result of analysis, we found out that there are much differences in the teaching of multiplication with three numbers, '${\times}10$', and '${\times}tens$'. We suggested some implication for the teaching of algorithm of natural number multiplication.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.1
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• pp.45-50
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• 1993

The phenomenon of wave diffraction due to structure is an important factor in the wave climate at the site As an approximation, the propagation characteristics of a regular wave train are usually used. instead of those of irregular waves. However, there are great differences between the diffraction coefficients of the irregular waves and monochromatic waves, as shown by Goda (1985). The spectral calculation method. one of the methods to deal with the transformation of random sea waves essentially consists of decomposing a spectrum of the irregular sea state Into various monochromatic components, and assembling the component results by linear superposition. Monoch romatic wave transformation model developed by Chen(1987) is used to make spectral calculation. These calculations agree closely with Goda et al. (1978)'s diffraction diagram for a thin semi-infinite breakwater.