• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.215-222
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• 1993

A general method is proposed for stiffness analysis of the leaf springs only using the geometric data and Young's modulus of the leaf springs. In this method, an engineering beam theory and Castigliano's theory are applied for the derivation of the stiffness of the leaf springs. To show realiability and effectiveness of this method, the stiffness from the proposed method is compared with the results for various types of leaf springs. From these comparisons the proposed method has been proved to be effective and reliable to estimate the stiffness of the leaf springs.

• Communications of Mathematical Education
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• v.18 no.1 s.18
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• pp.239-248
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• 2004

본 논문에서는 맨델브로트(Mandelbrot) 집합의 개념을 3차의 복소 다항식 z^3$+c 에 확장시켜 3차 분기집합을 정의하고, 이 집합의 2-주기 성분의 경계선 방정식과 관련 기하학적 성질을 고등학교 및 대학에서 다루는 미적분학 관점에서 분석하고자 한다. 복소수, 삼각함수, 매개함수, 함수의 극값, 미분 및 적분 등의 기초 이론을 활용하여 2-주기 성분의 경계선 방정식을 매개함수로 표시하고, 경계선의 내부 면적, 둘레 길이, 무게중심 등을 이론적으로 기술한다. 수학 소프트웨어인 매스매티카(Mathematica)를 활용하여 2-주기성분의 작도 및 기하학적 성질에 관한 수치 해석적 결과를 제시하고자 한다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2000.09a
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• pp.126-132
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• 2000

하수처리장의 수중확산관에서 방류되는 부력제트는 초기혼합, 중력확장, 이송-확산 등의 과정이 시간적, 공간적으로 규모가 상이한 범위에서 일어나며, 하수방류 해역의 주변수 흐름은 지형특성과 조석의 영향을 받아 3차원적 비정상류 특성을 나타낸다. 이러한 부력제트의 거동을 모의하기 위해서는 일반적으로 근역과 원역을 분할하여 예측하는 방법을 사용하는데, 초기혼합 과정과 중력환장 과정을 예측하기 위해서는 정상상태는 가정한 특성길이 모형이나 제트적분 모형을 사용하고, 원역으로의 이송-확산 과정을 모의하기 위해서는 농도 모형이나 임자추적 모형등을 사용한다. (중략)

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.1-9
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• 1999

For roughened annular pipes with diameter ratios of 0.26, 0.39, and 0.56 and with Reynolds numbers ranging 13,000 to 67,000, friction factor, autocorrelation coefficients, power spectral density functions, and integral length scales for each flow condition using X-type hot wire anemometry system are experimentally investigated. Distributions of these quantities show that the times which the streamwise autocorrelation coefficients become zero first increase with decreasing the radius ratios of concentric annuli and Reynolds numbers, however the power spectra density functions increase with increasing the radius ratios and Reynolds number.

• Computational Structural Engineering
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• v.7 no.2
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• pp.111-120
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• 1994

Cracks in rubber bonded to a rigid material such as steel are analyzed with the aid of a mixed finite element technique. Firstly the weak form is derived for finite element analysis of an incompressible material, and the Mooney-Rivlin form is assumed for the constitutive modeling of rubber. The numerical results from finite element analysis is examined to confirm the accuracy and convergence of solution by way of comparison to other numerical results. The interpretation of the J-integral for large elastic deformation as the energy release rate is confirmed, and the J-integral is calculated for varing crack length. The crack growth stability is discussed using the result of finite element analysis.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.127-133
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• 2007

SG-365 steel is an important material and used for manufacturing a pressure vessel which the gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the $J_{IC}$. It is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides, it improves the accuracy of toughness values, decreases a phenomenon of the tunneling and shear lip by the side groove.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.350-356
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• 2001

SG-50 steel is an important material and used for manufacturing a pressure vessel which the gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the an unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the J$_{IC}$. Because it is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides, it improves the accuracy of toughness values, decreases the scattering of them and tunneling and shear lip by the side groove.e.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1442-1446
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• 2004

The heat (mass) transfer characteristics on the blade surface of a first-stage turbine rotor cascade has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is employed for the measurements of the local heat (mass) transfer coefficient on the curved blade surface. The experiments are carried out for two free-stream turbulence intensities of 1.2% and 14.7%. The high free-stream turbulence results in more uniform distributions of heat load on the both pressure and suction surfaces and in an early boundary-layer separation on the suction surface. The heat (mass) transfer enhancement on the suction surface due to the endwall vortices is found to be relatively small under the high free-stream turbulence.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.4
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• pp.661-669
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• 1999

이 논문은 탄성지반위에 놓인 원호형 곡선보의 자유진동에 관한 연구이다. 회전관성 및 전단변형을 고려하여 두 개의 매개변수로 표현되는 탄성지반위에 놓인 원호형 곡선보의 자유진동을 지배하는 미분방정식을 유도하고, 이를 수치적분기법과 시행착오적 행렬값탐사법이 결합된 수치해석기법으로 해석하였다. 회전-회전, 회전-고정 및 고정-고정의 단부조건을 갖는 곡선보의 최저차모드 3개의 고유진동수를 산출하였다. 곡선보의 수평높이 지간길이비, Winkler 지반계수, 전단지반계수에 따른 고유진동수 변화를 분석하였으며, 회전관성 및 전단변형의 영향을 고찰하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.4
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• pp.241-250
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• 1986

Current distributions are the basis of analyzing and designing the antenna. In this paper, a method of deriving the current distribution of a spiral shaped thin wire scattere is proposed when plane wave is incident on it. The calculated results are also shown for severla spiral sizes and incidence angles selected. For numerical calculation, the method of point matching is used with a cubic B-spline function as a basis function.