• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.90-96
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• 2009

In this study, a generic airfoil designed by the inverse method was evaluated with several candidate airfoils as a first step. Each airfoil was compared with respect to aerodynamic performance to meet the requirement of HALE(high altitude long endurance) aircraft. The second step was to optimize the candidate airfoil using the couple of optimization formulations to down select an optimum airfoil. For the analysis of low Reynolds number 2D flow, Drela's MSES was used. After comparing the aerodynamic results, the best airfoil was chosen to construct the baseline 3D wing. The Navier-Stokes code was used to evaluate the overall aerodynamic performance of designed wing with other wings. The results show that the designed wing has the best performance compared with other wings.

• Journal of Multimedia Information System
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• v.6 no.4
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• pp.245-250
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• 2019

In this paper, we propose an ellipsoid modeling method for coding of a face depth picture. The ellipsoid modeling is firstly based on a point of a nose tip which is defined as the lowest value of the depth in the picture. The proposed ellipsoid representation is simplified through a difference of depth values between in the nose tip and in left or right boundary point of the face. Parameters of the ellipsoid are calculated through coordinates and depth values to minimize differences from the actual depth pixels. A picture is predicted by the modeled ellipsoid for coding of the face depth picture. In simulation results, an average MSEs between the face depth picture and the predicted picture is measured as 20.3.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.205-206
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• 2008

We propose load balancing algorithm based on cross layer designing for MIMO OFDM system. When there are many users using data service, base station(BS) should distribute traffic. Moreover, cross layer design gives benefit managing radio resource and network bandwidth management. Proposed cross layer load balancing technique manages both BS's bandwidth allocation and MS’s power control. One BS request bandwidth to other BSes and other BSes reduce each bandwidth. And BSes reduce power of sub carriers for reserving available bandwidth of backhaul. MSes that didn't get service can be served by obtaining bandwidth from other BSes. The simulation result shows more users can be served and cell throughput was increased

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.8-16
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• 2014

Two-dimensional prediction capability of several analysis codes, such as XFOIL, MSES, and KFLOW, is compared and analyzed based on computational results of airfoil flows. To this end the transition transport equations are coupled with the Navier-Stokes equations for the prediction of the natural transition and the separation-induced transition. Experimental data of aerodynamic coefficients are used for comparison with numerical results for the transitional flows. Numerical predictions using the transition transport model show a good agreement with experimental data. Discrepancies have been found in the prediction of the pressure drag are mainly caused by the difference in the far-field circulation correction methods.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.901-909
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• 2013

A skewed double power function distribution is defined by a double power function distribution. We shall evaluate the coefficient of the skewness of a skewed double power function distribution. We shall obtain an approximate maximum likelihood estimator (MLE) and a moment estimator (MME) of the skew parameter in the skewed double power function distribution, and compare simulated mean squared errors for those estimators. And we shall compare simulated MSEs of two proposed reliability estimators in two independent skewed double power function distributions with different skew parameters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.969-975
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• 2018

The main function of the tracking radar is to automatically track the target. The amplitude-comparison monopulse radar utilizes a monopulse radar to estimate the angular components of a target. In this paper, the operating performance of the amplitude-comparison monopulse radar is quantitatively analyzed via the MSEs, with considerations on additive noise. The performance of the amplitude comparison monopulse radar can be predicted by comparing it with an approximated estimate.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.8 no.3
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• pp.1-16
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• 2013

The purpose of study is to promote the development of medium size enterprises(MSE) by analyzing the causal relationship between technology acquisition strategy and firms' performance. In this study, we use the number of intellectual property, sales growth rates, and return on sales as proxy variables of technological and financial performances. This study includes internal R&D investment, cooperative R&D with academy, foreign technologies transferred, and their interaction effects as the independent variables. The results of study are as follows. Frist, R&D Investment, Foreign Technologies Transferred and their interaction effects are positively influence on technological performance. Second, Cooperative R&D with academy and the interaction effects of R&D Investment and Cooperative R&D with academy are negative influence on technological performance. On the other hand, all of the main independent variables and the interaction effects have non-significant relationships with financial performances. These results imply that technological innovation efforts of MSEs do not effectively increase their financial performances. Furthermore, technological supports of government and academy on MSEs' innovation do not effectively increase their innovation outputs. Finally, this study discussed its theoretical and practical implications and the limitations of the study.

• The Journal of the Acoustical Society of Korea
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• v.14 no.4
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• pp.5-11
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• 1995

In this paper, we design the new high-speed seek algorithm which can access the data of disk (in 3.5-inch optical disk drive). When seek the target track on optical disk in high-speed using the ref-T. E(Reference Tracking Error) and sample pulse signal, it's always possible high-speed seek without re-check and compensation for error by the ref_T. E and sample pulse signal. The performance test result is represented as follow ; it is satify the average seek time of 28mses.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.81-91
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• 2017

The performances of lifting surfaces are particularly critical in specific flight conditions like takeoff and landing. Different systems can be used to increase the lift and drag coefficients in such conditions like slat, flap or ailerons. Nevertheless they increase the losses and make difficult the mechanical design of wing structures. Morphing surfaces are a compromise between a right increase in lift and a reduction of parts movements involved in the actuation. Furthermore these systems are suitable for more than one flight condition with low inertia problems. So, flap and slats can be easily substituted by the corresponding morphing shapes. This paper deals with a genetic optimization of an airfoil with morphing flap with an already optimized nose. Indeed, two different codes are used to solve the equations, a finite volume code suitable for structured grids named ZEN and the EulerBoundary Layer Drela's code MSES. First a number of different preliminary design tests were done considering a specific set of design variables in order to restrict the design region. Then a RANS optimization with a single design point related to the take-off flight condition has been carried out in order to refine the previous design. Results are shown using the characteristic curves of the best and of the baseline reported to outline the computed performances enhancements. They reveal how the contemporary use of a morphing acting on the nose of the main component and the trailing edge of the flap drive towards a total not negligible increment in lift.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.63-68
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• 2004

The capacity of MIMO systems is numerically analyzed when channel estimation error exists. The analysis shows that the capacity is influenced by Mean Square Error (MSE) as well as average Signal to Noise Ratio (SNR). Furthermore, in this paper we present the standard selecting a channel estimator suitable to a system owing to get a tolerable channel estimation error in a given average SNR and channel capacity loss. The simulation results show that the tolerable MSEs for 1 bps/Hz capacity loss are about 10$^{-2}$ and 10$^{-4}$ at n dB and 40 dB average SNR, respectively.