• Journal of Electrical Engineering and information Science
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• v.1 no.2
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• pp.134-144
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• 1996

In this paper, we propose a new access method, called the HG-tree, to support indexing and retrieval by image content in large image databases. Image content is represented by a point in a multidimensional feature space. The types of queries considered are the range query and the nearest-neighbor query, both in a multidimensional space. Our goals are twofold: increasing the storage utilization and decreasing the area covered by the directory regions of the index tree. The high storage utilization and the small directory area reduce the number of nodes that have to be touched during the query processing. The first goal is achieved by absorbing splitting if possible, and when splitting is necessary, converting two nodes to three. The second goal is achieved by maintaining the area occupied by the directory region minimally on the directory nodes. We note that there is a trade-off between the two design goals, but the HG-tree is so flexible that it can control the trade-off. We present the design of our access method and associated algorithms. In addition, we report the results of a series of tests, comparing the proposed access method with the buddy-tree, which is one of the most successful point access methods for a multidimensional space. The results show the superiority of our method.

• Journal of computational fluids engineering
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• v.5 no.2
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• pp.38-46
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• 2000

It has been indicated that the rotor/stator interaction has distinct causes of unsteadiness, such as the viscous vortex shedding, wake/stator interaction and potential rotor/stator interaction. In this paper, the mechanism of unsteady potential interaction in one stage axial compressor is numerically investigated for blade row ratio 1:1 and 2:3 at design point and for blade row ratio 2:3 at off-design point in two-dimensional view point. The numerical technique used is the upwind scheme of Van-Leer's Flux Vector Splitting(FVS) and Cubic spline interpolation is applied on zonal interface. In this study the flow unsteadiness due to potential interaction are found to be larger in blade row ratio 2:3 than in 1:1. The total pressure rise in blade row ratio 2:3 is closer to the real value in design point than that in 1:1. The change of unsteady pressure amplitude according to the variation of stator exit pressure is very small.

• Journal of the Korea Furniture Society
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• v.18 no.4
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• pp.337-344
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• 2007

This study explored contemporary furniture theory and practice in Postmodernism mentioned as one of a kind furniture based on ideas from the tradition since Modernism. Qualitative conceptual analysis as the principal methodology was used to explore the postmodern furniture adopting or reflecting ornament from the tradition presented as postmodern furniture designers' point of view differently and variously. Thus, the examples about one of a kind or one-off furniture were dealt with Postmodern ideas appeared in the doubt over Modernism, Post-Modern furniture ideas from the traditional and Modern architecture, ornamental ism, Postmodern theorists, Postmodern furniture and the criteria. As a result, although one of a kind furniture design appealed newly from and based on the ornament of the tradition has been identified as new design like one of a kind furniture which shows lack of function, the piece with the meaningful ornament makes people happier in their daily life. Hence, one of a kind furniture, a work of art, has been required as striking a balance both function or comfort and aesthetics or beauty which makes the people more enjoyable.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.53-56
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• 2008

An ejector is a fluid machinery to be utilized for mixing fluids, maintaining vacuum, and transporting them. The Ejector is applied for a variety of industrial fields such as refrigerators and power plants. It is adopted to recycle anode off gas safely in 5kW Molten Carbonate Fuel Cell system of KEPRI(Korea Electric Power Research Institute). The ejector is placed at mixing point between the anode off gas and the cathode off gas or the fresh air. In this study, the entrainment ratio is measured according to the diametrical ratio of nozzle to throat. In addition, the performance curve of the ejector and the differential pressure in diffuser is observed.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.11
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• pp.984-990
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• 2002

We propose a new type of nonlinear fixed interval smoother to which an existing nonlinear smoother is modified. The nonlinear smoother is derived from two-filter formulas. For the backward filter. the propagation and the update equation of error states are derived. In particular, the modified update equation of the backward filter uses the estimated error terms from the forward filter. Data fusion algorithm, which combines the forward filter result and the backward filter result, is altered into the compatible form with the new type of the backward filter. The proposed algorithm is more efficient than the existing one because propagation in backward filter is very simple from the implementation point of view. We apply the proposed nonlinear smoothing algorithm to off-line navigation system and show the proposed algorithm estimates position, and altitude fairly well through the computer simulation.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.64-71
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• 2018

It is essential to understand the characteristics of gas turbine components in order to carry out an off-design analysis of a gas turbine engine. In this study, a micro gas turbine engine test system was constructed to understand the performance characteristics of gas turbines. The temperature and pressure in the flow path of the micro gas turbine was collected by measuring the engine spool speed, and a compressor map was constructed by using the experimental data. The exhaust gas was collected at the turbine outlet and the combustion efficiency was calculated. An off-design performance analysis at ground static was performed using GasTurb software by applying the compressor map and combustion efficiency obtained from the experimental data. Futhermore, we compared and evaluated the analysis results with engine operating data.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.7-16
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• 2008

Severe congestion is happening at urban freeway off-ramps in Seoul. Major causes of congestion at off-ramps are a shortage of capacity and inefficient signal operations at the downstream intersection at off-ramps. It is necessary to control congestion by improving design or operations in the downstream intersection. In this study, the authors analyzed the case of the Jungdong interchange that was improved for design in the downstream intersection. When a freeway and an arterial road cross, diamond interchanges are usually selected with a single-point urban interchange (SPUI) as an alternative. To compare the effectiveness of a diamond interchange with a SPUI, the authors applied these two configurations to the Jungdong interchange using a simulation. The result of the analysis shows that congestion at off-ramps in diamond interchanges can be reduced by improving signal operations such as the application of "4 phase with overlaps" and that diamond interchanges are more efficient than a SPUI with a frontage road. Efficient operation of the downstream intersection by these findings can minimize congestion of not only the downstream intersection but also the freeway mainline.

• Smart Structures and Systems
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• v.24 no.3
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• pp.345-360
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• 2019

The shear keys are set in a seismic isolation system to resist the long-term service loadings, and are cut off to isolate the earthquakes. This paper investigated the influence of shear keys on the seismic performance of a vertical spring-viscous damper-concave Coulomb friction isolation system by an incremental dynamic analysis (IDA) and a performance-based assessment. Results show that the cutting off process of shear keys should be simulated in a numerical analysis to accurately predict the seismic responses of isolation system. Ignoring the cutting off process of shear keys usually leads to untrue seismic responses in a numerical analysis, and many of them are unsafe for the design of isolated structure. And those errors will be increased by increasing the cutting off force of shear keys and decreasing the spring constant of shear keys, especially under a feeble earthquake. The viscous damping action postpones the cutting off time of shear keys during earthquakes, and reduces the seismic isolation efficiency. However, this point can be improved by increasing the spring constant of shear keys.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.11-17
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• 2012

The one way fluid structure interaction analysis on advanced propeller blade for next generation turboprop aircraft. HS1 airfoil series are selected as a advanced propeller blade airfoil. Adkins method is used for aerodynamic design and performance analysis with respect to the design point. Adkins method is based on the vortex-blade element theory which design the propeller to satisfy the condition for minimum energy loss. propeller geometry is generated by varying chord length and pitch angle at design point. Blade sweep is designed based on the design mach number and target propulsion efficiency. The aerodynamic characteristics of the designed Advanced propeller were verified by CFD(Computational Fluid Dynamic) and showed the enhanced performance than the conventional propeller. The skin-foam sandwich structural type is adopted for blade. The high stiffness, strength carbon/epoxy composite material is used for the skin and PMI(Polymethacrylimide) is used for the foam. Aerodynamic load is calculated by computational fluid dynamics. Linear static stress analysis is performed by finite element analysis code MSC.NASTRAN in order to investigate the structural safety. The result of structural analysis showed that the design has sufficient structural safety. It was concluded that structural safety assessment should incorporate the off-design points.

• Journal of KIBIM
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• v.8 no.2
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• pp.10-18
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• 2018

BIM technologies store, share and integrate the information produced in each sector of the construction industry. From this point on, it increases the efficiency of the work. Currently, quantity take-off and process schedule are derived separately based on BIM technology. When calculating the quantity by process, relevant information shall be collected, reinterpreted, and reevaluated as required by the practice. The purpose of this study is to develop an integrated process and quantity management system through BIM collaboration and to build prototypes for steel structures. The main research is to build a construction BIM model for steel structures and a process BIM model through BIM collaboration. Furthermore, necessary information was selected and processed according to the user's needs for integrated management. Relevant integration outcomes are visualized graphically to maximize utilization. Through these studies, a system for integrated control of processes and supplies is provided, and the results are expected to contribute to the improvement of working efficiency and are easily and quickly reflected in design change and process change. In this study, we intended to enhance the usability of information by linking process schedules with quantity calculations based on BIM. Thus, the process for integrated control of the quantity of structural components by process unit and the BIM based schedule information was established. In addition, the efficiency of the information link of the integrated management system was considered for design changes and process schedule changes.