• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.26-31
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• 2007

Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve both real density and grain refinement of metallic powders. ECAP (Equal Channel Angular Pressing), one of the most promising processes in SPD, was used for the powder consolidation method. For understanding the ECAP process, investigating the powder density as well as internal stress, strain distribution is crucial. We investigated the consolidation and plastic deformation of the metallic powders during ECAP using the finite element simulations. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method. Effects of processing parameters on densification and density distributions were investigated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.2
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• pp.137-146
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• 1990

A series of images whose sized and resolutions differ by a constant factor are called an image pyramid. Because the images at high levels are small, large object can be detected on high levels of the pyramid at low cost, But in this way, the boundaries of objects are not accurately localized. Therefore the pyramid algorithms extracte the objects by segmentation the constructed image using bottom-up method and description it in an original resolution using inverse bottom-up method. In this paper, we can project an object down to the next lower level of the pyramid and apply to the boundary adjustment algorithm at that level to localize it more precisely. We repeat the process at successively lower levels. In this paper, we present a method of boundary adjustment using an image pyramid to obtain optimal boundary. The performance of the proposed algorithm is compared to those of the conventional method in term of subjective quality of object boundary.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.327-329
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• 1998

Up-Propagation is an algorithm for inverting and learning neural network generative models. Sensory input is processed by inverting a model that generates patterns from hidden variables using top-down connections. The inversion process is iterative, utilizing a negative feedback loop that depends on an error signal propagated by bottom-up connections. The error signal is also used to learn the generative model from examples. the algorithm is benchmarked against principal component analysis in experiments on images of handwritten digits.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1011-1025
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• 2017

The geological conditions surrounding the Jijiapo Tunnel of the Three Gorges Fanba Highway project in Hubei Province are very complex. In this paper, a 3-D physical model was carried out to study the evolution process of filling-type fracture water inrush and mud gush based on the conditions of the section located between 16.040 km and 16.042 km of the Jijiapo Tunnel. The 3-D physical model was conducted to clarify the effect of the self-weight of the groundwater level and tunnel excavation during water inrush and mud gush. The results of the displacement, stress and seepage pressure of fracture and surrounding rock in the physical model were analyzed. In the physical model the results of the model test show that the rock displacement suddenly jumped after sustainable growth, rock stress and rock seepage suddenly decreased after continuous growth before water inrushing. Once water inrush occured, internal displacement of filler increased successively from bottom up, stress and seepage pressure of filler droped successively from bottom up, which presented as water inrush and mud gush of filling-type fracture was a evolving process from bottom up. The numerical study was compared with the model test to demonstrate the effectiveness and accuracy of the results of the model test.

• International Journal of Advanced Culture Technology
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• v.12 no.3
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• pp.67-72
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• 2024

The algorithm is applied on the premise that the image generated by AI can be recognized and used smoothly by the user. Other assets are not exposed to the user or discarded because they are unnecessary or unfamiliar. This study aims to expand the scope of the utility of the image generated by AI, which is used as a high-level tool in the design field. To this end, we first examined human information processing and reflection in AI by the cognitive paradigm by examining previous studies and cases, and discussed the value of expansion by focusing on creativity and bottom-up processing of AI's self-organization. Considering the human recogmition process that instinctively grasps an object, the following AI usability was proposed. It is to utilize AI as a high-level tool applied appropriately to human perception, or to utilize the derivative itself by bottom-up self-organization. In addition, it is to set the algorithm to the minimum intervention so that basic elements such as shape, color, size, texture, and movement are composed of figure-ground according to the human perception process that instinctively grasps an object, and to utilize the results. Limiting the use of AI to a tool suitable for human perception and information processing or production by designers or general users is to operate only a part of the convenience and usability of AI. The image creation through AI's self-organization, as seen from the cognitive paradigm, is a step toward opening a new era of design where technical aesthetics meets devices, just as design has been constantly developing in pursuit of novelty and differentiation due to its nature.

• Proceedings of the KSRS Conference
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• v.2
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• pp.643-646
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• 2006

This paper addresses the approach to extract linear features from satellite imagery using an efficient segmentation method. The extraction of linear features from satellite images has been the main concern of many scientists. There is a need to develop a more capable and cost effective method for the Iranian map revision tasks. The conventional approaches for producing, maintaining, and updating GIS map are time consuming and costly process. Hence, this research is intended to investigate how to obtain linear features from SPOT satellite imagery. This was accomplished using a discontinuity-based segmentation technique that encompasses four stages: low level bottom-up, middle level bottom-up, edge thinning and accuracy assessment. The first step is geometric correction and noise removal using suitable operator. The second step includes choosing the appropriate edge detection method, finding its proper threshold and designing the built-up image. The next step is implementing edge thinning method using mathematical morphology technique. Lastly, the geometric accuracy assessment task for feature extraction as well as an assessment for the built-up result has been carried out. Overall, this approach has been applied successfully for linear feature extraction from SPOT image.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.173-178
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• 2001

The cost on transmission and election of precast concrete members largely depends on the weight of them. In this study, the weight of prestressed precast beam could be reduced by control the section and prestressing force to meet the required strength on the basis of the optimum process. The top and bottom concrete stress of the section considered is required to check according to each construction step for this process. The original rectangular beam weight could be reduced up to 50~39% due to the development of a U-beams from the optimum process.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.674-682
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• 2012

A new intelligent stereo vision sensor system was studied for the motion and depth control of unmanned vehicles. A new bottom-up saliency map model for the human-like active stereo vision system based on biological visual process was developed to select a target object. If the left and right cameras successfully find the same target object, the implemented active vision system with two cameras focuses on a landmark and can detect the depth and the direction information. By using this information, the unmanned vehicle can approach to the target autonomously. A number of tests for the proposed bottom-up saliency map were performed, and their results were presented.

• Journal of Agricultural Extension & Community Development
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• v.17 no.3
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• pp.385-418
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• 2010

This study aimed to find the way to help participants build capacity in rural development projects, through some case studies and Q-methodology. Decentralization and diffusion of bottom-up approach in rural development projects are the main contextual factors in this study. With the ethos of bottom-up approach in rural development, the human and financial inputs for capacity building increased drastically in the area of rural development policy. Four types of capacity building methods were identified in this study; training, consulting, learning organization, and forum. Theses methods were used more at planning step than implementation step in rural development projects. The government's effort to strengthen leadership in rural areas should be continued. The existing government's training program for capacity building had better include more diverse clients. Actions for capacity building should be centered on the needs of the participants in fields. Especially, organizing learning units is very important. Governments' rural development policy should establish the proper process which can help local actors plan their projects with enough time span.

• Journal of Powder Materials
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• v.11 no.3
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• pp.233-241
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• 2004

In this study, bottom-up type powder processing and top-down type SPD (severe plastic deformation) approaches were combined in order to achieve both full density and grain refinement of Al-20 wt% Si powders without grain growth, which was considered as a bottle neck of the bottom-up method using the conventional powder metallurgy of compaction and sintering. ECAP (Equal channel angular pressing), one of the most promising method in SPD, was used for the powder consolidation. The powder ECAP processing with 1, 2, 4 and 8 passes was conducted for 10$0^{\circ}C$ and 20$0^{\circ}C$ It was found by microhardness, compression tests and micro-structure characterization that high mechanical strength could be achieved effectively as a result of the well bonded powder contact surface during ECAP process. The SPD processing of powders is a viable method to achieve both fully density and nanostructured materials.