• Structural Engineering and Mechanics
• /
• 제17권1호
• /
• pp.29-50
• /
• 2004

A total life model was developed to assess the service life of aging aircraft. The primary focus of this paper is the development of crack growth life projection using the response surface method. Crack growth life projection is a necessary component of the total life model. The study showed that the number of load cycles N needed for a crack to propagate to a specified size can be linearly related to the geometric parameter, material, and stress level of the component considered when all the variables are transformed to logarithmic values. By the Central Limit theorem, the ln N was approximated by Gaussian distribution. This Gaussian model compared well with the histograms of the number of load cycles generated from simulated crack growth curves. The outcome of this study will aid engineers in designing their crack growth experiments to develop the stochastic crack growth models for service life assessments.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 춘계학술대회 논문집
• /
• pp.383-389
• /
• 2013

Rotor system is a very important part which produces lift, thrust and control force in helicopter. Component of rotor system must endure various flight load for the required life. In helicopter rotor system, bearingless rotor system is the highest technology rotor system compare with articulated and hingeless rotor system. Baaringless rotor system is not include mechanical flap hinge, lag hinge and pitch bearing. Bearingless rotor component flexbeam which made by composite material has conduct hinge and bearing role instead of mechanical flap hinge, lag hinge and pitch bearing. These characteristics has less part number and lass weight than others. In this paper, conduct safe life analysis of bearingless composite component flexbeam and torque tube applying to utility helicopter load condition.

• Journal of the Korean Data and Information Science Society
• /
• 제6권1호
• /
• pp.105-110
• /
• 1995

In this paper, we shall convey preservation of some partial orderings and closures of some positive ageing classes under k-out-of-n systems of like components. That is, if the life time of a component A is larger than that of a component B in any of the NBU, DMRL, NBUE, HNBUE, NBUFR and NBUFRA orderings, then a k-out-of-n system formed by i.i.d.. components of type A has larger life time, in that ordering, than that of a similar system consisting of n i.i.d. components type of B. And using these partial orderings, closures of positive aging classes(NBU, DMRL, NBUE, HNBUE, NBUFR and NBUFRA) under the coherent system like components.

• Structural Engineering and Mechanics
• /
• 제4권4호
• /
• pp.347-364
• /
• 1996

Presently welded components are designed using S/N curves which predict only the fatigue life of the component. In order to ascertain the condition of the weld at any intermediate period of its life inspection is carried out. If cracks are detected in a weld fracture mechanics is used to find their remaining life. A procedure for assessment is developed here that can be used to verify the condition of a weld before inspection is carried out to detect cracks. This simple method has been developed using linear fracture envelopes by combining S/N curves with linear elastic fracture mechanics.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.690-693
• /
• 2005

In this paper, probabilistic distribution of fatigue life of chassis component is determined statistically by applying the design of experiments and the Pearson system. To construct $p-\varepsilon-N$ curve, the case that fatigue data are random variables is attempted. Probabilistic density function(p.d.f) for fatigue life is obtained by design of experiment and using this p.d.f fatigue reliability about any aimed fatigue life can be calculated. Lower control arm and rear torsion bar of chassis component are selected as examples for analysis. Component load histories, which are obtained by multi-body dynamic simulation for Belsian load history, are used. Finite element analysis are performed using commercial software MSC Nastran and fatigue analysis are performed using FE Fatigue. When strain-life curve itself is random variable, probability density function of fatigue life has very little difference from log-normal distribution. And the case of fatigue data are random variables, probability density functions are approximated to Beta distribution. Each p.d.f is verified by Monte-Carlo simulation.

• Applied Biological Chemistry
• /
• 제42권4호
• /
• pp.366-368
• /
• 1999

• Applied Biological Chemistry
• /
• 제49권4호
• /
• pp.334-338
• /
• 2006

장수풍뎅이 유충의 MeOH추출물에서 얻어진 n-BuOH 분획으로부터 silica gel column chromatography를 반복하여 핵산성분을 분리하였으며, NMR, MS 및 IR 등의 스펙트럼 데이터를 해석하여 inosine으로 동정하였다. Inosine을 지표성분으로 하여 $NH_2$-column을 이용한 HPLC 분석방법을 확립하였고, 열풍건조한 시료와 원적외선 건조기로 건조한 장수풍뎅이 유충 시료 중의 inosin의 함량을 각각 0.003% 및 0.055%로 정량분석하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.384-389
• /
• 2008

An accelerated fatigue test is essentially required to maintain the reliability of the actual structure of KTX under operation conditions. However, actual fatigue life cannot be obtained if specimens are not adequate to the conventional fatigue test. Moreover component maker did not provide data of loading stress (S) - cycles at the failure (N). In this study, we suggest a prediction method of the S-N curve for establishing an accelerating test under various load levels. Load history was acquired from the field tests. A Rainflow method was used on the cycle counting of the field load data, and then, an S-N curve was obtained through the iteration process under the condition that the damage index satisfies to 1 in the Miner's rule.

• 한국정밀공학회지
• /
• 제24권2호
• /
• pp.110-117
• /
• 2007

In this paper, probabilistic distribution of chassis component fatigue life is determined statistically by applying the design of experiments and the Pearson system. To construct p - ${\varepsilon}$ - N curve, the case that fatigue data are random variables is attempted. Probabilistic density function (p.d.f) for fatigue life is obtained by the design of experiment and using this p.d.f fatigue reliability, any aimed fatigue life can be calculated. Lower control arm and rear torsion bar of chassis components are selected as examples for analysis. Component load histories which are obtained by multi-body dynamic simulation for Belsian load history are used. Finite element analysis is performed by using commercial software MSC Nastran and fatigue analysis is performed by using FE Fatigue. When strain-life curve itself is random variable, the probability density function of fatigue life has very little difference from log-normal distribution. And the cases of fatigue data are random variables, probability density functions are approximated to Beta distribution. Each p.d.f is verified by Monte-Carlo simulation.

• 한국수산과학회지
• /
• 제45권6호
• /
• pp.586-593
• /
• 2012

To identify the food component characteristics of seven oysters(four cultured oysters and two wild oysters Crassostrea gigas and one dendely lamellated oyster Ostrea denselamellos Korean name beotgul) in Korea, the proximate, fatty/amino acid, mineral compositions, texture, color, chemical and taste compounds were investigated. The proximate compositions were not significantly different between cultured and wild oysters, whereas beotgul had lower levels of crude protein, ash and lipid content, and a higher carbohydrate content. The amino nitrogen contents of the three main types were 232.8-258.2, 160.5-213.9, and 218.5 mg/100 g, respectively, and the salinities were 1.5-1.7, 1.5-1.8, and 0.9%, respectively. Regarding the muscle texture, the shearing forces were 95-114, 105-132, and 170 g, respectively. Amounts of total amino acids of cultured, wild oysters and beotgul were 9,004-10,198, 8,165-8,942, and 7,767 mg/100 g, respectively. The major amino acids were aspartic acid (Asx), glutamic acid (Glx), proline, alanine, leucine, phenylalanine, lysine and arginine. Regarding inorganic ions, beotgul had much lower Fe and S contents than the cultured and wild oysters. The major fatty acids of cultured and wild oysters were 16:0, 18:0, 16:1n-9, 18:1n-9, 22:1n-9, 16:4n-3, 20:5n-3, and 22:6n-3, and there was little difference between the two. Beotgul had a higher polyenes ratio, i.e., 20:5n-3, and a lower monoenes ratio than the cultured and wild oysters. The free amino acid contents of cultured, wild oysters and beotgul extracts were 1,444-1,620, 1,017-1,277, and 1,144 mg/100 g, respectively, and the major free amino acids were taurine, glutamic acid, glycine, alanine, tryptophan, ornithine, and lysine. There was a little difference in the glycine, tryptophan, ornithine, and arginine contents.