1,720,963 research outputs found
사용후 핵연료의 중간건식저장에 대한 열유체 실험 및 해석
No full text학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2011.2, [ xii, 132 p. ]The experimental and numerical studies of interim storages for nuclear spent fuels have been performed to investigate thermal-hydraulic characteristics of the dry storage systems and to propose new methodologies for the analysis and the design. Three separate researches have been performed in the present study: (a) Development of a scaling methodology and thermal-hydraulic experiment of a single spent fuel assembly simulating a dry storage cask; (b) Full-scope simulation of a dry storage cask by the use of Computational Fluid Dynamics (CFD) code; (c) Thermal-hydraulic design of a tunnel-type interim storage facility.
In the first study, a scaling methodology has been developed to design a scaled-down canister. The scaling was performed in two steps. For the first step, the height of a spent fuel assembly was reduced from full height to half height. In order to consider the effect of height reduction on the natural convection, the scaling law of Ishii and Kataoka (1984) was employed. For the second step, the quantity of spent fuel assemblies was reduced from multiple assemblies to a single assembly. The scaling methodology was validated through the comparison with the experiment of the TN24P cask. The Peak Cladding Temperature (PCT), temperature gradients, and the axial and radial temperature distribution in the nondimensional forms were in good agreement with the experimental data. Based on the developed methodology, we have performed a single assembly experiment which was designed to simulate the full scale of the TN24P cask. The experimental data was compared with the CFD calculations. It turns out that their PCTs were less than the maximum allowable temperature for the fuel cladding and that the differences of their PCTs were agreed within 3℃, which was less than measurement uncertainty.
In the second study, the full-scope simulations of the TN24P cask were performed by FLUENT. In order to investigate the sensitivity of the numerical and physical parameters ...한국과학기술원 : 원자력및양자공학과
Development of metaphor-based interface design for VR manipulator
No full textThis research aims to establish a systematic approach to the development of metaphor and corresponding user models for VR interface design. Metapho rs have been used in various domains as means to extend the user’s mental models. Current research effort regarding VR interface design is mainly concentrated on static objects or visual information. In contrast, this research focuses on more integrating and dynamic aspects of VR interface such as interaction activities, task sequences, and operational motions. Finding principles for the selection and composition of appropriate metaphors is crucial for systematical dealing with this problem. User observation and task analysis were conducted to identify the cognitive difficulties that users face in performing the operations on VR objects. A VR manipulator that spatially provides the dynamic information and history was designed to mitigate those difficulties and cognitive load
Modeling users task performance on the mobile device: PC convergence system
No full textThis study aims to establish a model-based approach for user interface design that simultaneously considers the system's information hierarchy, users' task procedure knowledge, and system interfaces. The approach is based on a framework that contains multiple interaction models to express both system elements and users' knowledge. The framework evaluates system interface through the interaction between user's knowledge on interface, task procedure and information structure perceived by the user in the system. The interface is evaluated by its contribution to the users' task performance and system navigation. These three factors were defined as design factors that affect users' task performance. Through the crosscheck process of models, the relation between information, interface, and task procedure is calculated into combined difficulty index (CDI) that expresses the difficulty of a system interface that users would experience during the use of system. A user test was conducted for the validation of the CDI. The difficulties of the interface of a mobile healthcare system were predicted with the CDI, and the predictions were compared with the experimental results, where the users' performance showed consistence with the prediction. (c) 2006 Elsevier B.V. All rights reserved
COMPUTATIONAL STUDY OF THE SAFETY INJECTION TANK PERFORMANCE
No full textInside the Safety Injection Tanks (SIT) of APR1400s, fluidic devices (FD) are installed to passively control the mass flow discharged from the SIT, thus, eliminating the need for low pressure safety injection pumps. As passive safety mechanisms are emphasized more and more nowadays, it has become more important to understand the flow structure and the loss mechanism within the fluidic device. However, current computational fluid dynamics (CFD) calculations have had limited success in predicting the fluid flow accurately. This study proposes to find a more exact result using CFD and more realistic modeling. Preliminary CFD results match quite well with the experiment data. Comprehensive CFD results also match well with the experiment results and show interesting patterns which was analyzed using Fast Fourier Transform(FFT). Calculation is still in progress but current status shows promising result
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