• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.3 s.234
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• pp.295-305
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• 2005

To improve the aerodynamic effciency of TR-E2, a new configuration so called TR-E2Sl was introduced. TR-2251 is composed of different wing airfoil section and T-tail shape compared with TR-E2. Wind tunnel test for TR-EBS1 had been performed by changing the incidence angles of wing and deflection angles of control surfaces such as elevator and rudder. Also the on/off effect of ventral fin attached underneath of AFT fuselage was tested. Test result showed that variations of wing incidence angle did not cause any severe differences in aerodynamic characteristics. Longitudinal and directional characteristics of TR-E2S1 show stable for the pitch and yaw motions. However, the lateral stability of TR-E2S1 is not stable for a certain control surface deflection.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.9
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• pp.803-809
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• 2001

The present paper presents the experimental results of pressure drip of water flow in annuli with spirally corrugated inner tubes in the turbulent flow regime. To understand the underlying physical phenomena responsible for heat transfer enhancement, pressure drop data documented elsewhere are combined to compare with those obtained from the present experiment for the Reynolds numbers of 1,000 to 8,000. Friction factors were found to be functions of trough depth, pitch and angle, and the annulus radius ratio. Friction factor increases in the spirally fluted tubes were larger than those in the corrugated tubes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.377-383
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• 1999

In this study, the behavior of frost formation according to surface characteristics in the fin-tube heat exchanger has been examined experimentally. The results show that the thickness of the frost which is attached to the hydrophilic heat exchanger becomes thin and the air pressure drop is smaller than that of bare aluminium heat exchanger However, the frost mass of hydrophilic heat exchanger is more than the bare one. Hence, high density frost is attached to hydrophilic heat exchanger. The sensible and latent heat flux of hydrophilic heat exchanger is bigger than that of bare one, but the increasing amount is very small and the improvement of thermal performance is also very small. The variation of fin-pitch of heat exchanger shows little influence on frost formation and hydrophilic heat exchanger loses its surface characteristics rapidly with increasing relative humidity.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.100-105
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• 2001

The present paper is to present the results of studied of pressure drop in annuli with corrugated and spirally fluted inner tubes for the turbulent flow regime. To understand the underlying physical phenomena responsible for heat transfer enhancement, flow mechanism documented elsewhere are combined with pressure drop measurements to confirm the friction factors obtained from the annuli with the grooved inner tubes for the Reynolds number of 1000 to 8000. Friction factors were found to be functions of trough depth, pitch and angle, and the annulus radius ratio. friction factor increases in the spirally fluted tubes were larger than those in the corrugated tubes.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.83-86
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• 2015

Taking the four-wheel bogie landing gear as an example, the force status of truck-like landing gear during the landing impact was analyzed and the simulation model of four-wheel bogie landing gear was established. Firstly, a landing gear prototyping model was established using CATIA and imported to LMS Virtual.lab. Secondly, dynamic analysis of the landing impact was simulated with the established model. Finally, with the help of LMS Virtual.lab's parametric design ability, the effects of landing approach and truck pitch angle on the landing performance, truck motion and truck beam strength were studied. These conclusions will be useful to the design and analysis of the truck.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.134.1-134.1
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• 2012

The radiation belt structure can be approximately reproduced by a form of diffusion equation, which takes into account the radial diffusion process as well as those in pitch angle and energy. The solution of the equation depends on several factors including initial and boundary conditions, diffusion coefficients, and plasmapause location. In this paper, we have attempted to determine a set of approximate functions for the energetic electron fluxes near the outer edge of the outer belt in terms of solar wind variable. We used the electron flux data from SST onboard the THEMIS spacecraft and determined its correlation with solar wind conditions in a systematic way. The functions were determined separately for different energy channels from ~30 keV up to 719 keV. Our determination of these functions allows us to predict the radial boundary condition for the electron flux, which can be implemented in a forecast model.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.839-847
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• 2004

In this study, the flow characteristics within supersonic cascades are numerically investigated by using Fine Turbo, a commercial CFD code. Cascade flows are computed for three different inlet conditions. : a uniform supersonic inlet condition, a linear nozzle and a converging-diverging nozzle located in front of cascades. The effect of inlet conditions is compared and flow characteristics including shock patterns and shock-boundary layer interaction are analyzed. Also the effect of design parameters such as pitch-chord ratio, blade angle and blade surface curvature on the flow within supersonic cascades are studied.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.66-71
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• 2007

Development of a locomotive mechanism for the capsule type endoscopes will largely enhance their ability to diagnose disease of digestive organs. As a part of it, there should be provided a detection device of their position in human organs for the purpose of observation and motion control. In this paper, a permanent magnet outside human body was employed to project magnetic field on a capsule type endoscope, while its position dependent flux density was measured by three hall-effect sensors which were orthogonally installed inside the capsule. In order to detect the 2-D position data of the capsule with three hall-effect sensors including the roll, pitch and yaw angle, the permanent magnet was extra translated during the measurement. In this way, the 2-D coordinates and three rotation angles of a capsule endoscope on the same motion plane with the permanent magnet could be detected. The working principle and performance test results of the capsule position detection device were introduced in this paper showing that they could be also applied to 6-DOF position detection.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.627-630
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• 2003

This work presents a numerical procedure to optimize the shape of three-dimensional channel with angled ribs mounted on one of the walls to enhance turbulent heat transfer. The response surface method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of flow and heat transfer. SST turbulence model is used as a turbulence closure. The width-to-height ratio of the rib, rib height-to-channel height ratio, pitch-to-rib height ratio and attack angle of the rib are chosen as design variables. The objective function is defined as a linear combination of heat-transfer and friction-loss related terms with weighting factor. D-optimal experimental design method is used to determine the data points. Optimum shapes of the channel have been obtained for the weighting factors in the range from 0.0 to 1.0.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.413-419
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• 2003

The paper presents a simulation model and analysis of a grid-connected variable speed wind energy conversion scheme (VSWECS) using the PSCAD/EMTDC software. The modeled system uses a variable speed drive, a fixed pitch angle, a synchronous generator as a wind generator and an AC-DC-AC conversion scheme, which facilitates the wind generation to efficiently operate under varying wind speed while connected to the distribution network. The power output of the WECS is controlled by the AC-DC-AC conversion scheme, the objective of which is to capture the maximum active power under varying wind conditions and to keep the voltage magnitude of the terminal bus at a specific level. Aerodynamic models are applied for a wind turbine model. An simulation analysis of the scheme in terms of its responding to wind variations is also presented.