• 소음진동
• /
• 제6권5호
• /
• pp.587-594
• /
• 1996

이 논문에서는 일정체적의 정다각형 단면을 갖는 보-기둥의 자유진동 및 좌굴하중을 지배하는 비분방정식을 유도하고 이를 수치해석하였다. 정다각형 단면의 단면깊이 변화식으로는 포물선식과 정현식을 채택하였고, 고정-고정, 회전-고정 및 회전-회전의 단부조건에 대하여 고유진동수 및 좌굴하중을 산출하였다. 수치해석의 결과로 무차원 고유진동수와 무차원변들 사이의 관계 및 무차원 좌굴하중과 단면비 사이의 관계를 그림에 나타내었다. 또한, 최강기둥의 단면비와 좌국하중을 산출 하였다.

• 한국강구조학회 논문집
• /
• 제9권2호통권31호
• /
• pp.221-228
• /
• 1997

이 논문은 일정체적 단순지지 보-기둥의 동적 최적단면의 결정에 관한 연구이다. 정다각형 단면의 단면깊이가 포물선으로 변화하는 보-기둥에 대한 자유진동을 지배하는 상미분방정식을 유도하였다. 이 미분방정식에는 축하중효과를 고려하였고, Runge-Kutta method와 Regula-Falsi method를 이용하여 미분방정식을 수치적분하고 고유진동수를 산출하였다. 수치해석 결과로부터 얻어진 진동수-단면비 곡선의 임계값들을 분석하여 동적 최적단면을 결정하고 이 결과들을 표 및 그림에 나타내었다.

• 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.

• Structural Engineering and Mechanics
• /
• 제70권2호
• /
• pp.199-207
• /
• 2019

In this paper, a semi-analytical method will be discussed for free vibration analysis of rotating beams with variable cross sectional area. For this purpose, the rotating beam is discretized through applying the transfer matrix method and assumed the axial force is constant for each element. Then, the transfer matrix is derived based on Euler-Bernoulli's beam differential equation and applying boundary conditions. In the following, the frequencies of the rotating beam with constant and variable cross sections are determined using the transfer matrix method in several case studies. In order to eliminate numerical difficulties in the transfer matrix method, the Riccati transfer matrix is employed for high rotation speed and high modes. The results are compared with the results of the finite elements method and Rayleigh-Ritz method which show good agreement in spite of low computational cost.

• 한국농공학회지
• /
• 제34권1호
• /
• pp.57-65
• /
• 1992

The main purpose of this paper is to present both the natural frequencies and mode shapes of tapered beams under tensile axial force. The differential equation governing planar free vibration for tapered beams under tensile axial force is derived as nondimensional form. The three kinds of cross sectional shape are considered in differential equation. The Runge-Kutta method and Determinant Search method are used to perform the integration of the differential equation and to determine the natural frequencies, respectively. The hinged-hinged, hinged-clamped, clamped-clamped and constraints are applied in numerical examples. The lowest four nondimensional natural frequencies are reported as the function of nondimensional tensile axial force. The fundamental natural frequencies are presented when section ratios and nondimensional axial forces are varied. The effects of cross sectional shapes are reported and some typical mode shapes are also presented.

• 한국식품조리과학회지
• /
• 제17권6호
• /
• pp.549-554
• /
• 2001

Thermal measurements were made for connective tissues of 5 different fish muscles by using a differential scanning calorimeter(DSC), and connective tissues between muscle fibers and the cross sections of muscle fibers were observed by a light microscope. Red sea bream(cultured and wild) and flounder(cultured, cultured with obosan and wild) were used in this study. It was found that the connective tissues of cultured and frozen fish muscle required less endothermic enthalpy and the endothermic peak temperature was lower than those of wild and fresh ones when they were shrunken and denatured. Therefore, it is likely that the former are more unstable to heat than the latter. The cultured flounder fed with obosan and wild flounder which contained more collagen than cultured flounder and the wild red sea bream showed clear connective tissues between fibers. The cross-section of cultured fish muscle fiber was larger than that of wild one. From these results, collagen content and thermal properties of collagen, cross section of muscle fibers seemed to contribute to the textural difference between wild and cultured fish.

• Steel and Composite Structures
• /
• 제2권3호
• /
• pp.223-236
• /
• 2002

An analytical procedure based on the transfer matrix method to estimate not only the natural frequencies but also vibration mode shapes of the thin-walled members composed of interconnected cylindrical shell panels is presented. The transfer matrix is derived from the differential equations for the cylindrical shell panels. The point matrix relating the state vectors between consecutive shell panels are used to allow the transfer procedures over the cross section of the members. As a result, the interactions between the shell panels of the cross sections of the members can be considered. Although the transfer matrix method is naturally a solution procedure for the one-dimensional problems, this method is well applied to thin-walled members by introducing the trigonometric series into the governing equations of the problem. The natural frequencies and vibration mode shapes of the thin-walled members composed of number of interconnected cylindrical shell panels are observed in this analysis. In addition, the effects of the number of shell panels on the natural frequencies and vibration mode shapes are also examined.

• 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.

• 대한전자공학회논문지
• /
• 제25권2호
• /
• pp.125-129
• /
• 1988

The acattering characteristics by the TE incident wave are analysed for its dielectric cylinder with arbitrary cross section partially covered by thin conductors. The integro differential equations consistent with boundary conditions of conductors and dielectric boundaries are derived by the equivalence principle. They are transformed into matrix equations by moment method. The rectangular dielectric ctlinder partially coverd by conductors at the upper and bottom side of the cylinder is chosen for the numerical example. Current distributions on conductors and sacttring cross sections by the cylinder are computed for the TE incident perpendicular to the conductor plane.

• 한국방사선학회논문지
• /
• 제10권5호
• /
• pp.337-341
• /
• 2016

중성자에너지 영역 0.003 eV에서 10 eV에 대해 천연 Sm의 Sm(n,${\gamma}$) 반응에 대한 중성자 포획단면적을 측정하였다. 교토대학교 원자로실험소의 46-MeV 전자선형가속기에서 발생되는 전자의 광핵반응에 의한 중성자를 사용하였고 TOF 방법으로 측정하였다. 사용한 검출기는 12개의 BGO($Bi_4Ge_3O_{12}$) 섬광체로 구성되었고 이 검출장치로 Sm(n,${\gamma}$) 반응으로부터 나오는 즉발감마선을 측정하였다. 검출장치는 중성자 생성 위치로부터 $12.7{\pm}0.02m$ 위치에 설치되었으며 $^{10}B(n,{\alpha}{\gamma})^7Li$ 반응을 이용해 Sm 시료에 입사되는 중성자 선속을 구하였다. 또한 중성자 선속의 변화를 확인하기 위해 $BF_3$ 검출기로 모니터링 하였다. Sm(n,${\gamma}$) 반응단면적 측정결과는 BROND 2.2에 의한 평가결과와 J. C. Chou 및 V. N. Kononov 의 측정값과 비교하였다.