• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.324-330
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• 2012

Dual bell nozzle is one of the most promising choices among the altitude adaptation nozzles. This facilitates having a forced, steady and symmetrical separation at lower altitudes and a controlled flow separation at the wall inflection point which prevents the generation of dangerous side loads. In order to ensure the attached flow in the second bell, a clear understanding of the flow transition is required. Hence the motivation of our study is to arrive at an optimum profile for the second bell, which allows a sudden and controlled transition. In this work, we designed the first bell using the conventional MoC and the second bell using an inverse MoC, imposing a pressure gradient constraint. A CFD analysis is also carried out. It is found that the separation point is near the inflection point within one fourth of the extension length or it is near the exit.

• Wind and Structures
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• v.32 no.4
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• pp.393-403
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• 2021

A comprehensive knowledge of the wind flow in hilly terrains is of great interest in many engineering applications, be it wind energy distribution for suitable site selection for wind farms, pollution dispersion, forest fire propagation or agrometerological studies. Several researchers have shown that wind flow over a hilly terrain may be significantly different when compared with the wind flow over a flat terrain. Complex hilly terrains may alter the wind speed to a great extent. Therefore, this effect of terrain must be properly assessed by designers and planners to arrive at a proper wind flow distribution. This paper reviews the work done in this area over the past three decades. Wind flow over two-dimensional hills and two-dimensional escarpments investigated in wind tunnels by various researchers is presented in this paper.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.559-564
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• 2001

Advanced gas turbine engines employ turbine entry temperatures so high that cooling of the turbine blades is essential. The coolant flow introduces losses which need to be minimized, and therefore it is important that the minimum amount of coolant is used. This work presents the result of the one-dimensional analysis and the effect of the boundary conditions on coolant flow rate in gas turbine blades.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.48-53
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• 1995

Recently, work of construction industry is not enough to do in tamping because of a lack of expert, advanced-age of worker, increase of structure of high-dengity arrangment and machanization of concrete pumping method Accordingly it is required for high-qualuily concrete with excellent flowability, Self-placeability and regregation registance. In this point of view, this study is investigated for requiremend properties of ultar-flow concrete using dimestic material as for development of Ultra-Flow concrete in the side of material

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.437-440
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• 2005

In the present work, characteristics of the flow in CAGE of a steam turbine LP/HP Bypass control valve for thermal power plant are investigated. The flow field is analyzed numerically by solving steady three-dimensional Reynolds-averaged Navier-Stokes equations. Shear stress transport (SST) model is used as turbulence closure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.9
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• pp.888-894
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• 2001

Advanced gas turbine engines employ turbine entry temperatures so high that cooling of the turbine blades is essential. The coolant flow introduces losses which need to be minimized, and therefore it is important that the minimum amount of coolant should be used. This work presents the result of the one-dimensional analysis and the effect of the boundary conditions on coolant flow rate in gas turbine blades.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.294.1-294.1
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• 2003

At pH 7.4 (physiological pH), skin is permselective to cations, due to the net negative charge of the current passing channels (pores) in skin. This causes the convective solvent flow (electroosmotic flow) from anode to cathodal direction. In this work, we have investigated several factors (pH. current density and ionic strength) that can affect the electroosmotic flow. (omitted)

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.1
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• pp.138-154
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• 2008

Geo-special technologies are being adopted in variety fields since the 3rd NGIS plan that was started at 1996. However, the required system or structure to guarantee the up-to-date validity and accuracy of the geospatial data - the most fundamental elements of the technology - was not constructed yet. All the activities related to geospatial data, including topographical map and numerical base map, are all implemented in separate way; from change of geographical objects and features, data gathering, and database construction to distribution, transfer and sharing of these data. The data model that links all the activities are required that enables consistent data-flow and effective and systematic work-flow. In this study, economic data renewal and exchange method was proposed, and benefit-cost analysis was implemented by comparing the conventional work-flow to newly proposed work-flow. The case study was implemented using the model that was adopted in Daegu metropolitan city, and the model was developed by reflecting these results.

• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.99.2-100
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• 1999

• Journal of the Korean Academy of Esthetic Dentistry
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• v.21 no.1
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• pp.83-92
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• 2012