• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.6
• /
• pp.367-374
• /
• 2022

This papter presents the use of the automatic differential method based on the backpropagation method to obtain the design sensitivity and its application to topology optimization considering the stress constraints. Solving topology optimization problems with stress constraints is difficult owing to singularities, the local nature of stress constraints, and nonlinearity with respect to design variables. To solve the singularity problem, the stress relaxation technique is used, and p-norm for stress constraints is applied instead of local stresses for global stress measures. To overcome the nonlinearity of the design variables in stress constraint problems, it is important to analytically obtain the exact design sensitivity. In conventional topology optimization, design sensitivity is obtained efficiently and accurately using the adjoint variable method; however, obtaining the design sensitivity analytically and additionally solving the adjoint equation is difficult. To address this problem, the design sensitivity is obtained using a backpropagation technique that is used to determine optimal weights and biases in the artificial neural network, and it is applied to the topology optimization with the stress constraints. The backpropagation technique is used in automatic differentiation and can simplify the calculation of the design sensitivity for the objectives or constraint functions without complicated analytical derivations. In addition, the backpropagation process is more computationally efficient than solving adjoint equations in sensitivity calculations.

• The KIPS Transactions:PartB
• /
• v.16B no.5
• /
• pp.341-346
• /
• 2009

The motion data glove is a representative human-computer interaction tool that inputs human hand gestures to computers by measuring their motions. The motion data glove is essential equipment used for new computer technologiesincluding home automation, virtual reality, biometrics, motion capture. For its popular usage, this paper attempts to develop an inexpensive visual.type motion data glove that can be used without any special equipment. The proposed approach has the special feature; it can be developed as a low-cost one becauseof not using high-cost motion-sensing fibers that were used in the conventional approaches. That makes its easy production and popular use possible. This approach adopts a visual method that is obtained by improving conventional optic motion capture technology, instead of mechanical method using motion-sensing fibers. Compared to conventional visual methods, the proposed method has the following advantages and originalities Firstly, conventional visual methods use many cameras and equipments to reconstruct 3D pose with eliminating occlusions But the proposed method adopts a mono vision approachthat makes simple and low cost equipments possible. Secondly, conventional mono vision methods have difficulty in reconstructing 3D pose of occluded parts in images because they have weak points about occlusions. But the proposed approach can reconstruct occluded parts in images by using originally designed thin-bar-shaped optic indicators. Thirdly, many cases of conventional methods use nonlinear numerical computation image analysis algorithm, so they have inconvenience about their initialization and computation times. But the proposed method improves these inconveniences by using a closed-form image analysis algorithm that is obtained from original formulation. Fourthly, many cases of conventional closed-form algorithms use approximations in their formulations processes, so they have disadvantages of low accuracy and confined applications due to singularities. But the proposed method improves these disadvantages by original formulation techniques where a closed-form algorithm is derived by using exponential-form twist coordinates, instead of using approximations or local parameterizations such as Euler angels.

• The Journal of Korean Philosophical History
• /
• no.28
• /
• pp.237-266
• /
• 2010

This thesis is to check whether the modernization, promoted mainly in 1960-1970 of Korea may have the relations with Confucian values or have a gap between this and that, and have the question about the idea of the appearance of modernity under Park Jung-hee's government, which is based on the viewpoint that Confucianism would have been made ill use of or have contribution to the nation-directing modernity, especially to the modernization of people. In a sense this thesis demands the overcome of the modern ills such as social dichotomy, leaving out matters of locals, and neglecting the diversities and singularities of creatures, resulted from efficiencies and uniformity caused by nation-centralism. At first Confucianism have represented humanism with a view to finding the mean between the two of locals, affairs, and men. As such it has seek to find centrality, which means my real mind for meeting outward things or the optimum as the mean, the best state between of the two. The political doctrines modified from Confucian learnings including chung, hyo, samgang, and oryun worked as the mechanism for finding nation-directing modernity. As a result we have lived in the modernity, strengthened by nation-centralism. And the leading concepts in related with Neo-Confucianism had people lose their spaces of desire for their own future or got them to be narrow. Accordingly the modernization of Korea means not an integral space in which we can achieve what we want in various aspects, but a deficient space to be complemented, resulted from the centralization of all conditions of life, dichotomous way of approaching matters by nation-centralism, far from being the essence of Confucianism. In the end the rapid modernization by the leaders in Korea has given rise to the concentration politics, economy, and so forth on Seoul as the center. Then we should deeply reflect the deficiency state of centralism like this and how Confucianism would have been responsible for it and will give how to relieve the unequal centralism of nation. Now for this matter we would like to expect our study in the future.v