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기하학적 초기형상결함을 갖는 보강 원통의 충격좌굴 신뢰성 해석
김두기 한국소음진동공학회 1996 소음 진동 Vol.6 No.6
In this paper, buckling reliability analyses of stiffened cylinder with random initial geometric imperfection under axial impact load are performed by the combined response surface method. The effect of random geometric imperfection on the failure probability and reliability is recognized quantitatively. Buckling reliability decreases with the increase of mean value, cov of initial geometric imperfection under the same external load. Buckling probability under impact load is greater than those under static load with the same condition. From the probabilistic characteristics of imapct buckling load, relation between reliability index and safety parameter can be obtained in addition to the relation between load and reliability index. And those results can be used to determine the range of required safety parameter and acceptable imperfaction.
충격하중을 받는 원통의 최초좌굴시간의 변동성에 대한 기하학적 초기결함의 영향
김두기 한국전산구조공학회 1997 전산구조공학 Vol.10 No.1
본 논문에서는 랜덤한 축대칭 기하학적 초기결함을 갖는 원통이 축방향 충격하중을 받는 경우의 반경방향 변위가 임계기준치를 최초로 통과하는 확률론적 충격좌굴 파괴시간을 해석할 수 있는 방법을 제시하였다. 랜덤한 기하학적 초기결함의 생성을 위해 초기결함의 평균함수 및 상관함수를 이용하여 확률장을 형성하는 방법을 사용하였다. 본 논문에서 제시된 방법은 실제적인 기하학적 초기결함이 갖는 불확실성을 취급하는데 적절하고 실용적이므로 이를 고려한 원통의 구조안전도해석에 이용할 수 있다. In this paper a method is suggested for the probabilistic analysis of impact buckling failure time of cylinder with random axisymmetric geometric imperfection under axial impact. Failure is assumed as axisymmetric radial deformation exceeds the given criteria for the first time. For the generation of random geometric initial imperfection, random field theory by mean function and autocorrelation function of geometric imperfection is used. Suggested method is useful for the treatment of the randomness of realistic geometric imperfection and can be used for the structural safety analysis of cylinder considering its effect.
HMR 제품의 경험가치와 컬러 마케팅이 소비자의 재구매 의도에 미치는 영향
김두기,최진경 한국식생활문화학회 2018 韓國食生活文化學會誌 Vol.33 No.3
The home meal replacement (HMR) food industry began in 1980, and it has grown rapidly as a major food business for both consumers and the food industry since the development of industrialization and societal changes. Many researchers investigated a variety of HMR food product characteristics. On the other hand, previous studies have focused only on topics in limited study areas. Therefore, this study examined the effect of color marketing and the value of experience on the consumer behaviors. This study used a survey to collect the respondents' opinions about HMR food products. The study results showed that the characteristics of color marketing and the experience value of the HMR products influenced the consumers' attitudes. Moreover, consumers' attitudes affected their repurchase behavior. The results suggest that marketers of HMR food products should use colors that show the characteristics of products to appeal to consumers. In addition, HMR products should be developed in line with what consumers value the most; for example, consumers value their previous experience with the products and the characteristics of the products.
Iterative neural network strategy for static model identification of an FRP deck
김두기,Jintao Cui,Hyeong Yeol Seo,Young Ho Lee 국제구조공학회 2009 Steel and Composite Structures, An International J Vol.9 No.5
This study proposes a system identification technique for a fiber-reinforced polymer deck with neural networks. Neural networks are trained for system identification and the identified structure gives training data in return. This process is repeated until the identified parameters converge. Hence, the proposed algorithm is called an iterative neural network scheme. The proposed algorithm also relies on recent developments in the experimental design of the response surface method. The proposed strategy is verified with known systems and applied to a fiber-reinforced polymer bridge deck with experimental data.
김두기,김종인,김두훈 한국소음진동공학회 2001 한국소음진동공학회 논문집 Vol.11 No.5
As bridge design is advancing toward the performance-based design. it becomes increasingly important to monitor and re-evaluate the long-term structural performance of bridges. Such information is essential in developing performance criteria for design. In this research. sensor systems for long-term structural performance monitoring have been installed on two highway bridges. Pre1iminary vibration measurement and data analysis have been performed on these instrumented bridges. On one bridge, ambient vibration data have been collected. based on which natural frequencies and mode shapes have been extracted using various methods and compared with those obtained by the preliminary finite element analysis. On the other bridge, braking and bumping vibration tests have been carried out using a water truck In addition to ambient vibration tests. Natural frequencies and mode shapes have been derived and the results by the breaking and bumping vibration tests have been compared. For the development of a three dimensional baseline finite element model, the new methodology using a neural network is proposed. The proposed one have been verified and applied to develop the baseline model of the bridge.