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박철민,박경진,이완익 한양대학교 공학기술연구소 1992 공학기술논문집 Vol.1 No.1
General structural optimization is utilized to minimize the weight of structures while satisfying constraints imposed on stress, displacements and natural frequencies, etc.. Sandwich structures consist of inside core and outside face sheets. The selected sandwich structures are isotropic sandwich beams and isotropic sandwich plate. The face sheets are treated as membrane and assumed to carry only tensions, and the core is assumed to carry only the transverse shear. The characteristics of the varying area are considered by adding the projected component of the tension to the transverse shear. The bending theory and energy method are adopted for analyzing sandwich beams and plates, respectively. In the optimization process, the cost function is the weight of a structure, and a deflection and stress constraints are considered. Design variables are thickness and tapering coefficients which determine the shape of a structure. An existing optimization code is used for solving the formulated problems.
불연속 구조물의 배치최적설계시 민감도 오차해석에 관한 연구
이광원,박경진 한양대학교 공학기술연구소 1995 공학기술논문집 Vol.4 No.1
Configuration optimization is a structural optimization method where the geometrical shape of the structures can be changed during the optimization process. Sensitivity informations are required in the general optimization and quite costly. Especially, they are extremely expensive in the structural optimization where the finite element analysis is utilized. Since the nodal coordinates are regarded as design variables in the configuration optimization, the sensitivities according to the nodal coordinates must be calculated. The characteristics of the configuration optimization is in that the transformation matrix in the finite element analysis is a function of design variables. Thus the sensitivity calculation in the configuration optimization is even more complicated. For the efficient sensitivity calculations, various methods have been proposed. They are the analytic method(AM), overall finite difference method(OFD), and semi-analytic method(SM). The semi-analytic method consists of the forward and central difference method. This study has been conducted to choose an appropriate method for compared based on the mathematical and numerical aspects. Some standard structural problems are selected for the evaluations.
고병갑,박경진,이완익 한양대학교 공학기술연구소 1995 공학기술논문집 Vol.4 No.1
Bellows is a familiar component in piping systems as it provides a relatively simple means of absorbing thermal expansion and providing system flexibility. In routine piping flexibility analysis by finite element methods, bellows is usually considered to be straight pipe runs modified by an appropriate flexibility factor; maximum stresses are evaluated using a corresponding stress concentration factor. The aim of this study is to develop a bellows finite element, which similarly includes more complex shell type deformation patterns. This element also does not require flexibility or stress factors, but evaluates more detailed deformation and stress patterns. The proposed bellows element is a 3-D, 2-noded line element, with three degrees of freedom per node and no bending. It is formulated by including additional 'internal' degrees of freedom to account for the deformation of the bellows corrugation; specifically a quarter toroidal section of the bellows, loaded by axial force, is considered and the shell type deformation of this is include by way of an approximating trigometric series. The stiffness of each half bellows section may be found by minimising the potential energy of the section for a chosen deformation shape function. An experiment on the flexibility is performed to verify the reliability for bellows finite element.
최우석,박경진 漢陽大學校 工學技術硏究所 1998 工學技術論文集 Vol.7 No.1
실제로 구조물에 작용하는 하중은 동하중이다. 그러나 동하중을 그대로 처리하는 것은 매우 고가이기 때문에 해석 및 설계 시 동적계수 등에 의해 변환된 정하중이 사용된다. 동적계수는 일반적으로 경험 등에 의해 결정된다. 따라서 구조물의 어떤 부분은 이러한 정하중하에서 적절치 못하게 설계될 수 있다. 이러한 방법들은 신뢰성이 다소 떨어지고 설계 시 해석의 정확성에 의문을 제기할 수 있다. 본 논문에서는 동하중을 정하중으로 변환하는 해석적 방법을 제안한다. 변환과정은 수학적으로 유도되었다 아울러 개발한 방법의 응용성을 논의하는 과정에서 이 결과가 구조최적설계과정에 어떻게 사용될지를 제시한다. All the forces in the real world act dynamically on structures. Since dynamic loads are extremely difficult to handle in analysis and design, static loads are utilized with dynamic factors. Dynamic factors are generally determined from experiences. Therefore, structural engineers often come up with unreliable solutions. An analytical method is proposed for the transformation of dynamic loads into equivalent static loads. The process is derived and evaluated mathematically. Applicabilities of the method to structural optimization are discussed.
이효지,차경희,박진희 한국조리과학회 2004 한국식품조리과학회지 Vol.20 No.4
The purpose of this study was to investigate the quality characteristics of Kugija-Injeulmi by varying the ingredient ratio of Lycii fructus powder (4, 6 and 8%). According to sensory evaluation of Kugija-Injeulmi, as the ratio of Lycii fructus powder was increased, the bitterness, hardness and chewiness all increased. It was found that Kugija-Injeulmi made of glutinous rice was moistened and softened with the addition of more Lycii fructus powder, but it was rougher than Kugija-Injeulmi made of glutinous rice flour. As a result of textural analysis of Kugija-Injeulmi, the hardness, adhesiveness, gumminess and chewiness increased as the amount of Lycii fructus powder increased, whereas the cohesiveness decreased. Kugija-Injeulmi made of glutinous rice was moister than Kugija-Injeulmi made of glutinous rice flour. The overall-acceptability was negatively correlated with coarseness. The overall-acceptability of Kugija- Injeulmi made of glutinous rice was much higher than that made of glutinous rice flour. From the above results, the most advisable mixture ratio of Kugija-Injeulmi is as follows : Kugija-Injeulmi add 282g (94%) glutinous rice flour, Lycii fructus powder 18g (6%) and salt 3g. The moisture content was 42.22%.
Role of the modified Saengmaeksan(mSMS) in L-NAME-induced hypertension model
Jin Ki Jung,Hobin Moon,Won Hee Nam,Yun-Hwan Kang,Se-Jin Kim,Young Mi Seok,Hyun Hee Leem,Ji-Woon Jeong,Yu Jin Park,Min Ju Kim,Chae Suk Ra,Jiyoung Seo,Hye Won Shin,Bo Gyung Jang,Hyo Jung Kim 한국실험동물학회 2022 한국실험동물학회 학술발표대회 논문집 Vol.2022 No.7
Park, Shin-Young,Choi, Jin-Won,Chung, Duck-Hwa,Kim, Min-Gon,Lee, Kyu-Ho,Kim, Keun-Sung,Bahk, Gyung-Jin,Bae, Dong-Ho,Park, Sang-Kyu,Kim, Kwang-Yup,Kim, Cheorl-Ho,Ha, Sang-Do Korean Society of Food Science and Technology 2007 Food Science and Biotechnology Vol.16 No.2
Square root models were developed for predicting the kinetics of growth of Listeria monocytogenes in sesame leaves as a function of temperature (4, 10, or $25^{\circ}C$). At these storage temperatures, the primary growth curves fit well ($R^2=0.898$ to 0.980) to a Gompertz equation to obtain lag time (LT) and specific growth rate (SGR). The square root models for natural logarithm transformations of the LT and SGR as a function of temperature were obtained by SAS's regression analysis. As storage temperature ($4-25^{\circ}C$) decreased, LT increased and SGR decreased, respectively. Square root models were identified as appropriate secondary models for LT and SGR on the basis of most statistical indices such as coefficient determination ($R^2=0.961$ for LT, 0.988 for SGR), mean square error (MSE=0.l97 for LT, 0.005 for SGR), and accuracy factor ($A_f=1.356$ for LT, 1.251 for SGR) although the model for LT was partially not appropriate as a secondary model due to the high value of bias factor ($B_f=1.572$). In general, our secondary model supported predictions of the effects of temperature on both LT and SGR for L. monocytogenes in sesame leaves.