• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1935-1939
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• 2006

In this study, the new dispersion-correction terms are added to leap-frog finite difference scheme for the linear shallow-water equations with the purpose of considering the dispersion effects such as linear Boussinesq equations for the propagation of tsunamis. And, dispersion-correction factor is determined to mimic the frequency dispersion of the linear Boussinesq equations. The numerical model developed in this study is tested to the problem that initial free surface displacement is a Gaussian hump over a constant water depth, and the results from the numerical model are compared with analytical solutions. The results by present numerical model are accurate in comparison with the past models.

• 대한전자공학회논문지
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• 제25권8호
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• pp.884-892
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• 1988

An asymptotic solution of electromagnetic waves scattered by an arbitrary-angled dielectric wedge in the E-polarized plane wave incidence is obtained by adding a correction to the physical optical fields given in the previous paper of these companion papers, Part I. The source for the asymptotic correction field valid in the far-field region can be equivalent to the multipole line sources at the tip of the wedge, of which coefficients are evaluated numerically by solving a dual series equation. The corrected field patterns are plotted for the typical case treated in Part I.

• 전기학회논문지
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• 제59권2호
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• pp.417-422
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• 2010

When memory devices are exposed to space environments, they suffer various effects such as SEU(Single Event Upset). Memory systems for space applications are generally equipped with error detection and correction(EDAC) logics against SEUs. In this paper, several error detection and correction codes - RS(10,8) code, (7,4) Hamming code and (16,8) code - are analyzed and compared with each other. Each code is implemented using VHDL and its performances(encoding/decoding speed, required memory size) are compared. Also the failure probability equation of each EDAC code is derived, and the probability value is analyzed for various occurrence rates of SEUs which the STSAT-3 possibly suffers. Finally, the EDAC algorithm for STSAT-3 is determined based on the comparison results.

• 대한토목학회논문집
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• 제3권3호
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• pp.53-61
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• 1983

침투능을 계산하기 위한 공식으로서 Green-Ampt 공식은 식의 간편성과 정확성으로 인하여 많은 연구의 대상이 되어왔다. 그러나 이 공식의 변수인 습윤전선(Wetting Front)에서의 모세관 압력수두항은 연구자에 따라 해석이 많이 다르다. 침투능해석을 위하여 2개 유체의 흐름방정식의 해는 Green-Ampt 공식과 같은 형태를 가지므로서 Green-Ampt 공식의 모세관 압력 수두항을 결정할 수 있게 되었다. 이러한 2개 유체 해석에 의한 침투능 산정공식의 유도는 1개층으로만 구성되어 있는 경우에 이루어 졌으나 특성이 각각 다른 여러 층의 흙으로 구성 되어 있는 경우에는 아직 이루어진 바 없다. 본 논문에서는 이러한 2개 유체의 흐름 해석에 의하여 여러층의 흙인 경우 침투능 산정공식을 유도하였다.

• 한국전산유체공학회지
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• 제17권3호
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• pp.99-107
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• 2012

In this paper, the shock waves in compressible solids and liquids are simulated using a six-equation diffuse interface multiphase flow model that is extended to the Cochran and Chan equation of state. A pressure relaxation method based on a volume fraction function and a pressure-correction equation are newly implemented to the six-equation model. The developed code has been validated by a shock tube problem with liquid nitromethane and an impact problem of a copper plate on a solid explosive. In addition, a new problem, an impact of a copper plate on liquid nitromethane, has been solved. The present code well shows the wave structures in compressible solids and liquids without any numerical oscillations and overshoots. After the impact of a solid copper plate on liquid, two shock waves (one propagates into liquid and the other into solid) are generated and a material interface moves to the impacting direction. The computational results show that the shock velocity inside the liquid linearly increases with the impact velocity.

• 한국해안해양공학회지
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• 제16권2호
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• pp.57-63
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• 2004

지진해일파는 조석에 비하면 파장이 짧아 상대적으로 분산성이 장하므로, 먼 거리를 전파하는 경우에는 분산성을 고려하여 해석하여야 한다. 본 연구에서는 파동방정식에 기초한 일차원 유한요소모형을 이용하여 지진해일 전파를 수치모의할 때 시간단계를 2단계로 나누어 양해법을 사용하면서도 분산효과를 고려할 수 있는 능동적인 분산보정기법을 개발하였다. 제안된 기법을 이용하여 계산한 수치해와 파의 분산효과를 고려한 해석해의 비교를 통해 본 연구에서 제안한 분산보정기법의 타당성을 확인하였다.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.77-88
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• 2017

Correction Factor Method (CFM) is one of the earliest methods for simulating the actual behavior of structure according to construction sequences and practical implementation steps of the construction process which corrects the results of the conventional analysis just by the application of correction factors. The most important advantages of CFM are the simplicity and time-efficiency of the computations in estimating the final modified forces of the beams. However, considerable inaccuracy in evaluating the internal forces of the other structural members obtained by the moment equilibrium equation in the connection joints is the biggest disadvantage of the method. This paper proposes a novel method to eliminate the aforementioned defect of CFM by using the column shortening correction factors of the CFM to modify the axial stiffness of columns. In this method, the effects of construction sequences are considered by performing a single step analysis which is more time-efficient when compared to the staged analysis especially in tall buildings with higher number of elements. In order to validate the proposed method, three structures with different properties are chosen and their behaviors are investigated by application of all four methods of: conventional one-step analysis, sequential construction analysis (SCA), CFM, and currently proposed method.

• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.98-106
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• 2014

The effect of blockage ratio on wind tunnel testing of small vertical-axis wind turbine has been investigated in this study. Height and rotor diameter of the three blades Darrieus vertical axis wind turbine used in present test were 0.4m and 0.35m respectively. We measured the wind speeds and power coefficient at three different wind tunnels where blockage ratio were 3.5%, 13.4% and 24.7% respectively. The test results show that the measured powers have been strongly influenced by blockage ratio, generally increased as the blockage ratio increases. The maximum power at higher blockage ratio has been obtained at relatively high tip speed ratio compared with that at low blockage ratio. The measured power coefficients under high blockage ratio can be improved from proper correction using the simple correction equation based on blockage factor. In present study, the correction error for power coefficient can be less than 5%, however correction effectiveness reveals relatively poor at high blockage ratio and low wind speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.636-638
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• 2014

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 추계학술발표대회 요약집
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• pp.56-56
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• 2003