• Nuclear Engineering and Technology
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• 제23권1호
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• pp.12-19
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• 1991

본 연구에서는 반타원 표면결함의 응력세기계수를 계산하는 공학적-일반식을 유도하였다. 가중치함수를 이용하여 임의의 응력이 작용할 시에 평잔 및 실린더에 존재하는 반타원결함에 대한 응력세기계수 산출에 유한요소해석이나 탄성파괴 핸드북을 사용하지 않고 2차원적 해석방법을 이용한 단일화된 식으로서 쉽게 계산할 수 있는 방법을 제시하였다. 본 방법엘 의한 계산결과는 기존에 발표된 연구물에 제시된 값과 잘 일치하였으며, ASME의 산출방법보다도 현실적이며 실제 경우에 사용하기 용이함을 보여준다.

• Structural Engineering and Mechanics
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• 제20권4호
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• pp.451-463
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• 2005

Structural members commonly employed in marine and off-shore structures are usually fabricated from plates and shells. Collision of this class of structures is usually modeled as plate and shell structures subjected to dynamic impact loading. The understanding of the dynamic response and energy transmission of the structures subjected to low velocity impact is useful for the efficient design of this type of structures. The transmissions of transient energy flow and dynamic transient response of these structures under low velocity impact are presented in the paper. The structural intensity approach is adopted to study the elastic transient dynamic characteristics of the plate structures under low velocity impact. The nine-node degenerated shell elements are adopted to model both the target and impactor in the dynamic impact response analysis. The structural intensity streamline representation is introduced to interpret energy flow paths for transient dynamic response of the structures. Numerical results, including contact force and transient energy flow vectors as well as structural intensity stream lines, demonstrate the efficiency of the present approach and attenuating impact effects on this type of structures.

• Earthquakes and Structures
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• 제12권5호
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• pp.569-581
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• 2017

The Monte Carlo Simulation (MCS) based seismic fragility analysis (SFA) approach allows defining more realistic relationship between failure probability and seismic intensity. However, the approach requires simulating large number of nonlinear dynamic analyses of structure for reliable estimate of fragility. It makes the approach computationally challenging. The response surface method (RSM) based metamodeling approach which replaces computationally involve complex mechanical model of a structure is found to be a viable alternative in this regard. An adaptive moving least squares method (MLSM) based RSM in the MCS framework is explored in the present study for efficient SFA of existing structures. In doing so, the repetition of seismic intensity for complete generation of fragility curve is avoided by including this as one of the predictors in the response estimate model. The proposed procedure is elucidated by considering a non-linear SDOF system and an existing reinforced concrete frame considered to be located in the Guwahati City of the Northeast region of India. The fragility results are obtained by the usual least squares based and the proposed MLSM based RSM and compared with that of obtained by the direct MCS technique to study the effectiveness of the proposed approach.

• 대한기계학회논문집
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• 제15권1호
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• pp.201-208
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• 1991

본 연구에서는 균일 열유동이 접합면에 수직으로 흐르고 접합 경계면 균열의 열경계조건이 단열되어 있는 경우에 균질 및 접합재료 모두에 적용될 수 있는 열응세 기계수를 복소해석방법을 이용하여 구하고자 한다.

• Journal of the Korean Data and Information Science Society
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• 제21권3호
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• pp.555-560
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• 2010

One-dimensional approach to two-dimensional warranty data involves modeling us- age as a function of time. Iskandar (1993) suggests a simple linear model for usage. However, simple linear form of intensity function is of limited value to model the situa-tion where the intensity varies over time. In this study Weibull intensity is considered where the scale parameter is expressed in terms of different models. We will nd out how each parameter in the model a ects the warranty cost and which model gives a bigger number of failures within the two-dimensional warranty region.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.165-169
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• 2000

A simple method was suggested to calculate the stress intensity factor for a one-sided patched crack with finite thickness. To consider out-of-plane bending effect resulting from the load-path eccentricity, the spring constant as a function of the through-thickness coordinate z was calculated from the stress distribution in the un-cracked plate, ${\sigma}_{yy}(y=0,\;z)$, and the displacement for the representative single strip Joint, $u_y(y=0,\;z)$. The stress Intensity factors were obtained using Rose's asymptotic solution approach and compared with the finite element results. In short crack region, two results had a little difference. However, two results were almost same in long crack region. On the other hand, the stress intensity factor using plane stress assumption was more similar to finite element result than plane strain condition.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.172-181
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• 2003

In this study, the stress intensity factor of center crack tip is calculated by the superposition method when it is surrounded by symmetrically distributed small cracks. The values of stress intensity factors of center crack tips are compared with those of the center crack tips calculated by the superposition method. These compared errors are influenced by the locations of distributed small cracks. These errors are inspected. When small cracks overlap and approach near the center crack tip, the effect of interaction caused by these cracks becomes noticeable and these errors become larger. In case of multiple distributed small cracks except this case, the stress intensity factor of the center crack tip is easily calculated by the superposition method.

• 한국정밀공학회지
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• 제15권11호
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• pp.244-250
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• 1998

In this study, the stress intensity factors of center crack are analyzed when it is surrounded by symmetrically distributed small cracks. The values of stress intensity factors of the center crack are greatly influenced by the locations of distributed small cracks. When small cracks overlap or approach near the tip of a center crack, the effect of interaction arisen by these cracks becomes noticeable. In case of multiple distributed small cracks, the stress intensity factor of a center crack is found to be efficiently determined by the superposition method.

• 아태비즈니스연구
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• 제11권2호
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• pp.45-60
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• 2020

Purpose - This study examines the impact of company ownership nature and of the dual role of CEO and board chair on R & D investment intensity, as well as the moderating effect of this dual role. Most previous research focused on the impact of the dual role of CEO and board chair on firm performance. Design/methodology/approach - This study uses A-share companies listed on the Shenzhen and Shanghai stock exchanges in China from 2008 to 2017. The univariate and the multivariate regression analysis were hired In order to analyze the data. Findings - The results show that there is a significant negative relationship between state-owned companies and R & D investment intensity. In addition, there is a significant positive relationship between the dual role and R & D investment intensity. The effect of state ownership on R & D investment intensity is more negative when CEO-board chair duality exists. This means that in case of state-owned companies, if CEO serves as the board chair, the propensity to invest in R&D is further reduced. Research implications or Originality - This is a pioneering study that considers the joint effect of state-owned companies and dual role on R & D investment intensity in the Chinese economy.

• International Journal of Reliability and Applications
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• 제14권2호
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• pp.107-114
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• 2013

Modelling of failures is an important element of reliability modelling. Empirical modelling approach suitable for complex item is explored in this paper. First step of the empirical modelling approach is to plot hazard function, density function, Weibull probability plot as well as cumulative intensity function to see which model fits best for the given data. Next step of the empirical modelling approach is select appropriate model for the data and fit the parametric model accordingly and estimate the parameters.