• 한국소음진동공학회논문집
• /
• 제21권6호
• /
• pp.570-579
• /
• 2011

This paper deals with free vibrations of the circular curved beams with constant volume, whose cross sectional shapes are the circular solid cross-sections. Volumes of the objective beam are always held in constant regardless shape functions of the cross-sectional radius. The shape functions are chosen as the linear, parabolic and sinusoidal ones. Ordinary differential equations governing free vibrations of such beam are derived and solved numerically for determining the natural frequencies. In numerical examples, the hinged-hinged, hinged-clamped and clamped-clamped end constraints are considered. As the numerical results, relationships between frequency parameters and various beam parameters such as rise ratio, section ratio, elasticity ratio, volume ratio, slenderness ratio and taper type are reported in tables and figures.

• 융복합기술연구소 논문집
• /
• 제6권1호
• /
• pp.17-21
• /
• 2016

The analysis of circular plates under the constant pressure are simplified as the loading conditions of the circular manhole. The theoretical solution of circular plates with respect to the constant pressures are derived by using the governing equation of plate deflection. The deflection and the radial stress distributions were calculated by the theory. Finite element solutions were conducted with respect to the element types of the continuum elements. The most accurate element was selected by comparisons of the theoretical solutions and simulated solutions. The C3D8I element type in brick-type continuum elements gave in a good accordance with the theoretical solutions.

• International Journal of Fluid Machinery and Systems
• /
• 제10권1호
• /
• pp.63-75
• /
• 2017

Many axial fans have circular arc blades with constant thickness. It is still a challenging task to calculate their performance, i.e. to predict how large their pressure rise and pressure losses are. For this task a need for cascade data exists. Therefore, the designer needs a method which works quickly for design purposes. In the present contribution a design method for such cascades consisting of circular arc blades with constant thickness is described. It is based on a singularity method which is combined with a CFD-data-based flow loss model. The flow loss model uses CFD-data to predict the total pressure losses. An interpolation method for the CFD-data are applied and described in detail. Data of measurements are used to validate the CFD-data and parameter variations are conducted. The parameter variations include the variation of the camber angle, pitch chord ratio and the Reynolds number. Additionally, flow patterns of two dimensional cascades consisting of circular arc blades with constant thickness are shown.

• 설비공학논문집
• /
• 제4권2호
• /
• pp.137-145
• /
• 1992

coefficient precisely, experiments were carried out in three categories which contain the regime of (1) constant wire temperature (2) constant fluid temperature (3) constant temperature difference between wire and fluid. Measurements were made with electrically heated circular tungsten wire placed normal to air stream at the exit of jet. Heat transfer coefficient was increased with wire temperature increasing and decreased by fluid temperaure increasing and was not changed with varying both temperature if their difference were kept constant.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.540-545
• /
• 2001

An experimental study was conducted to compare the heat transfer characteristics of an impinging slot jet and three kinds of impinging circular jets. Thermochromic liquid crystal with an image processing system was employed to measure the temperature of impinging wall where constant heat flux condition was applied. The distribution of convective heat transfer coefficients were then evaluated for eight nozzle-to-surface distance settings for each jet cases. The cooling effect was linearly proportional to the number of nozzles for circular jet cases at the same nozzle exit speed. However, the heat transfer under constant volume flow rate was the most at single circular jet. It was concluded that the overall convective heat transfer was better at the circular jets than the slot jet.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 추계학술대회논문집
• /
• pp.716-720
• /
• 2006

In order to examine the effect of constant excitation on nonlinear interactions in vibrating modes of circular plates, we added a constant term to a harmonic excitation. A two-degree-of freedom system is derived by using the Galerkin's procedure. The system is shown to have quadratic and cubic nonlinearities subjected to a harmonic excitation.

• 한국소음진동공학회논문집
• /
• 제20권2호
• /
• pp.144-152
• /
• 2010

This paper deals with free vibrations of the tapered circular arches with constant volume, whose cross sectional shape is the solid regular polygon. Volumes of the objective arches are always held constant regardless shape functions of the cross-sectional depth. The shape functions are chosen as the linear, parabolic and sinusoidal ones. Ordinary differential equations governing free vibrations of such arches are derived and solved numerically for determining the natural frequencies. In the numerical examples, hinged-hinged, hinged-clamped and clamped-clamped end constraints are considered. As the numerical results, the relationships between non-dimensional frequency parameters and various arch parameters such as rise ratio, section ratio, side number, volume ratio and taper type are reported in tables and figures.

• 콘크리트학회논문집
• /
• 제11권3호
• /
• pp.81-88
• /
• 1999

원형 철근콘크리트 기둥의 전단보강철근에 의한 저항강도의 평가를 위하여 전단에 의한 사인장 균열 면을 관통하는 원형 전단보강철근의 횡하중 작용방향의 평균 인장력을 산정하였다 이를 위하여 원형 전단보강철근이 이루는 원의 중심선간 직경, 수직 배근간격 및 기둥축 방향에 대한 사인장 균열면을 고려하였으며, 이들 변수들을 이용하여 원형 전단보강철근의 유효단면적을 계산하는 공식을 제안하였다. 연구결과, 원형 전단보강철근의 유효단면적 계산을 위하여 근 10년 간 사용되어 온 상수 계수가 모든 경우에 일률적으로 사용될 수 없음을 보여주고 있다 즉, 기존에 사용되는 원형전단철근 유효단면적은 기둥의 전단저항강도의 계산에 있어서, 전단철근의 배근간격이 비교적 넓은 비내지진 지역에서는 안전 측의 예측을 하게 되어 구조물의 안전상 큰 문제가 없지만, 배근간격이 촘촘하거나 원통형강관을 사용하게 되는 내진 지역에서는 기둥의 전단저항강도를 실제보다 20% 정도 과하게 예측하여 구조물의 안전에 좋지 않은 결과를 낳을 수도 있다.

• 대한전자공학회논문지
• /
• 제25권12호
• /
• pp.1582-1585
• /
• 1988

A cavity perturbation technique is employed to determine the dielectric property of thin samples. Substrates in microwave integrated circuits are fabricated in sheet form and are expected to have a dielectric constant less than 10 and a dielectric loss better than 10**-3. This research aimed to determine both dielectric constant and dielectric loss with good accuracy. The tecynique makes use of thin circular disk samples placed in a right circular cylindrical cavity. The accuracy of measurements is within \ulcorner% for dielectric constnat and 3x10**-4 for dielectric loss.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제14권3호
• /
• pp.141-149
• /
• 2010

The aim of this work is to determine the quasi-static thermal stresses of an infinitely long circular cylinder having constant initial temperature under steady-state field. The arbitrary heat flux is applied on the lower surface and the upper surface of the cylinder is at initial temperature. The fixed circular edge is thermally insulated. The results are obtained in series form in terms of Bessel's functions. These have been computed numerically and illustrated graphically.