• Title/Summary/Keyword: 주기함수

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Modification of the Cubic law for a Sinusoidal Aperture using Perturbation Approximation of the Steady-state Navier-Stokes Equations (섭동 이론을 이용한 정상류 Navier-Stokes 방정식의 주기함수 간극에 대한 삼승 법칙의 수정)

  • 이승도
    • Tunnel and Underground Space
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    • v.13 no.5
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    • pp.389-396
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    • 2003
  • It is shown that the cubic law can be modified regarding the steady-state Navier-Stokes equations by using perturbation approximation method for a sinusoidal aperture variation. In order to adopt the perturbation theory, the sinusoidal function needs to be non-dimensionalized for the amplitude and wavelength. Then, the steady-state Navier-Stokes equations can be solved by expanding the non-dimensionalized stream function with respect to the small value of the parameter (the ratio of the mean aperture to the wavelength), together with the continuity equation. From the approximate solution of the Navier-Stokes equations, the basic cubic law is successfully modified for the steady-state condition and a sinusoidal aperture variation. A finite difference method is adopted to calculate the pressure within a fracture model, and the results of numerical experiments show the accuracy and applicability of the modified cubic law. As a result, it is noted that the modified cubic law, suggested in this study, will be used for the analysis of fluid flow through aperture geometry of sinusoidal distributions.

A note on the periodic solutions of the nonlinear suspension bridge equation (비선형 현수교 방정식의 주기함수로 나타나는 해에 대한 연구)

  • Han, Chun-Ho;Shim, Do-Sik
    • Journal of Industrial Technology
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    • v.17
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    • pp.125-130
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    • 1997
  • 이 논문에서는 비선형 빔방정식을 이용할 수 있는 현수교방정식의 존재하는 해의 개수를 조사하였다. 외부에서 주어지는 함수가 주기함수일 경우에 나타나는 여러 가지 성질들을 조사하였으며 주어진 항들의 계수가 상수인 경우 어떤 범위에서 몇 개의 해가 존재할 수 있는지를 조사하였다. Leray-Schauder degree를 이용하여 존재할 수 있는 해의 개수를 판별하는 근거로 삼았다. 특히 일정한 항의 계수가 변수를 포함하는 경우에 나타날 수 있는 변화에 대하여 조사하였다.

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Change of temperature patterns in Seoul (서울의 온도 패턴 변화)

  • Jang, Hak-Jin;Joo, Yong-Sung
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.1
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    • pp.89-96
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    • 2009
  • We examined the characteristics of temperature variation in Seoul between 1961 to 2008 using the spectral heteroscedastic model. The mean function in the propsed model explains the season effect using periodic functions and the overall increase using the quadratic regression spline. The variance function also had periodic functions to explain the seasonality of variance. We found that there has been annual mean temperature increase by about $1.5^{\circ}C$ for the last 48 years. The increase of annual mean temperature was mainly caused by the increase in winter, which made the amplitude decreased.

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Stress analysis for shotcrete lining on uneven tunnel perimeter (비평탄 굴착벽면의 숏크리트 라이닝에 대한 응력해석)

  • Lee, Seungdo;Moon, Hyun-Koo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.6
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    • pp.597-604
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    • 2015
  • When a tunnel is constructed by drilling and blasting operation, the excavated perimeter becomes uneven due to overbreak at the drill holes so that the thickness of shotcrete tends to be irregular. In this case, the conventional stress analyses for tunnel lining of a uniform thickness cannot be readily applicable. In this study, the profile of tunnel perimeter assumed to be sinusoidal in order to simulate the uneven tunnel perimeter and to control the thickness of shotcrete by using the amplitude and wavelength. By adopting the sinusoidal function to a theoretical solution of stress analysis for uniform lining, the range of axial stress of irregular shotcrete can be estimated. The applicability of the approximate solution has been verified by performing a series of numerical analyses for various conditions. It is shown that the axial stress of shorcrete is highly dependent upon the irregularity of shotcrete, together with the ground property and initial stress conditions. It is also shown the shear stress is dependent upon the wavelength, and the stress condition becomes unfavorable where the thickness of shotcrete is relatively small. The approach developed in this study shows that the stress state where the thickness is relatively small is unfavourable, and it is necessary to take complementary measures when installing shotcrete after blasting.

Formalization of Adsorption Isotherm for Heterogeneous Surface (Heterogeneous 표면 흡착등온식의 형식화)

  • Kim, Cheol-Ho;HwangBo, Seung
    • Proceedings of the KIEE Conference
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    • 2001.11a
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    • pp.288-289
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    • 2001
  • 흡착열공간분포를 외형적으로 포함하는 Heterogeneous 표면상의 흡착등온식을 형식화한다 그리고 흡착열공간분포는 위치에 대한 주기함수로서 주어지는 것임을 논한다. 본 논문에서 얻어진 결과를 재료의 박막형성 문제에 결부시켜 논의한다.

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A Study of the discrete for Numerical Approximation Functions by Fourier transform (Fourier 변환을 이용한 수치 근사 함수의 이산화에 관한 연구)

  • Song, Eun-Jee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2003.05a
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    • pp.367-370
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    • 2003
  • 과학자나 공학자들은 빛이나 소리와 같이 주기적인 특성을 갖는 현상을 연구하는 경우가 많다. Fourier 변환은 이러한 주기함수의 근사 함수를 구할 때 유용하게 이용되고 있다. 본 논문에서는 극좌표 표현되는 함수의 근사 함수를 구하는 문제를 다룬다 일반적으로 컴퓨터 상에 구현하기 위해서는 이산형 Fourier 급수전개를 이용하는데 지금까지는 근사 함수를 컴퓨터 상에서 구할 때 이산화 표본수를 경험에 의해 임의로 결정하여 이용하였으나 본 연구에서는 Fourier 변환의 성질을 이용하여 주어진 함수에 따라 필요한 이산화 표본 수를 자동적으로 결정하는 알고리즘을 제안한다.

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A study about caculating the heating load of the wall of underground space to be used undereground temperature (지중온도를 이용한 지하공간 벽체의 난방부하 계산에 관한 연구)

  • Jeong, Soo-Ill
    • Journal of the Korean Solar Energy Society
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    • v.28 no.1
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    • pp.19-24
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    • 2008
  • The energy crisis is culminating for the life of the fossil fuel in the future which is come to end at $30{\sim}40$ years. Moreover above 90% of the energy in our country depend on importing and the crisis is more seγious than it of other countries. So architects devote low energy house research and it means underground space research have become public opinion. But there is not an accurate and utility method calculating the heating load of underground space. In this study it is proposed that the heating load is calculated by setting adiabatic thichness of soil and predicting underground temperature. The prediction of the underground temperature is calculated by the latitude, the level, the distance from sea, the condition of earth surface.