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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Aeronautical & Space Sciences
Journal Basic Information
Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 28, Issue 7 - Oct 2000
Volume 28, Issue 6 - Sep 2000
Volume 28, Issue 5 - Aug 2000
Volume 28, Issue 4 - Jun 2000
Volume 28, Issue 3 - Apr 2000
Volume 28, Issue 2 - Mar 2000
Volume 28, Issue 1 - Feb 2000
Volume 28, Issue 8 - 00 2000
Selecting the target year
A Study on the Lift and Drag Characteristics of a Wing with Non-uniform Blowing from Lower Surface
Lim, Jin-Hyuk ; Kim, Hark-Bong ; Lee, Bong-Joon ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 1~1
Non-uniform blowing effect for a wing was studied to enhance aerodynamic performance of the wing which is subjected to wind shear during take-off & landing. Wind shear was simulated by a uniform flow impinging on the model, normal to the free stream. Rectangular wing models were designed and a wind tunnel tests were conducted to investigate the aerodynamic characteristics of the wings with non-uniform blowing from its lower surface. In this study, the experimental data were measured for the wing with and without non-uniform blowing in the wind tunnel. Selected data at several test conditions varying blowing location, blowing angles and jet momentum coefficient are discussed to find lift and drag coefficient trends. The experimental results showed that the wing with non-uniform blowing from lower surface has a higher lift to drag ratio than the wing without blowing and maximum lift to drag ratio is increased by 39% for a rectangular wing compared to the basic wing without blowing and also increase the lift to drag ratio reduced by simulated wind shear.
Byun, Sei-Jong ; No, Oh-Hyeon ; Kim, Jong-Am ; Park, Jong-Ju ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 10~10
The three-dimensional compressible Euler code was developed for the analysis of the supersonic flow field around 3-stage rocket system with boosters. Numerical simulations were performed at various angles of attack and Mach numbers. In order to analyze these flow fields, an overlapped grid system called 'Chimera grid system', is applied to the 3-dimensional Euler equation This grid system is quite efficient for the analysis of flows around complex geometry and flows under relative solid body motion, so is very appropriate for the present research objects. Communications between overlapped grids is achieved by the trilinear interpolation method which is robust and easily applicable to any code. AUSMPW+ scheme is used for spatial discretization, and MUSCL interpolation with Minmod limiter is applied for a higher order spatial accuracy. The split flux Jacobian of van Leer's flux Vector Splitting(FVS) algorithm is used for the matrix computation of the implicit part. Also Beam-Warming's approximate factorization(AF) scheme is used for the efficient calculation of the implicit part. Chimera grid scheme was applied to KSR-III and H-2 geometry under various flow conditions. Aerodynamic coefficients and their characteristics were examined from the numerical results.
Aerodynamic Characteristics of ARCH-50 Multipurpose Unmanned Helicopter Fuselage
Lee, Sang-Joon ; So, Soo-Hyun ; Hwang, Kum-Young ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 20~20
The effect of components attached at basic helicopter body on the aerodynamics characteristics of the ARCH-50 unmanned helicopter fuselage was experimentally investigated. The components tested in this study include rotor mast, landing gear, tail unit and spray tank. The angle of attack(
) and yaw angle(
) were varied in the range of
, respectively. The aerodynamic forces and moments of 1/3 scale model of the helicopter were measured ,using a 6-component sting balance and the flow around the helicopter model was visualized using a smoke-tube technique. As a result, with increasing the angle of attack, the drag and lift coefficients are increased as a whole and the minimum drag coefficient occurs in the range of
. The landing gear affects the drag coefficient mainly compared to other components. On the other hand, the tail unit plays important role on the lift coefficient and static stability of the helicopter. The helicopter model keeps the stability by attaching the tail nit, but becomes unstable due to stall of tail unit for
. As the yaw angle increases, the drag coefficient is increased a little, while the side force and yawing moment coefficients increase largely, affecting the static stability of the helicopter model.
A Shape Design Optimization of Transonic Airfoils by Using the Bezier Curve
Sohn, Myong-Hwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 29~29
A new method of applying the Bezier parametric curves to the shape design optimization is proposed. The proposed method uses the weighting parameters of the coordinates of the Bezier curve control-points as the design variables and the Wavier-Stokes equations as the flow analysis equations. Compared with the previous method which used the coordinates of the Bezier curve control-points themselves as the design variables, the design process of the new method proved to be much less dependent on the size of the design-variable perturbation. The proposed method also has much better convergence behavior and improvement of the objective functions in the lift maximization and drag minimization designs of transonic airfoils.
Rotor-Fuselage Interactional Aerodynamic Analysis Using Unstructured Meshes
Lee, Jong-Kook ; Kwon, Oh-Joon ; Kim, Jai-Moo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 36~36
A numerical method has been developed for the analysis of interactional aerodynamics of helicopter rotor and fuselage in forward flights. A 3-D steady compressible Euler solver is used to compute flows around helicopter fuselages. The time-averaged interactional effects between the rotor and the fuselage are calculated by modeling the rotor as an actuator disk carrying pressure jumps across the plane. Unstructured mesh is used to model complex rotor-fuselage configurations. Flow around a generic configuration was calculated for validations. Good agreements with the experiment in the time-averaged velocity and pressure distributions are obtained.
Passive Flutter Suppression of a Wing with External Store
Kim, Dong-Hyun ; Lee, In ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 46~46
In the case of a aircraft wing with external store, the mass and location of the external store can largely affect the dynamic stability and controllability. It is important problem to choose the proper location and to design the mechanism of pylon carrying auxiliary fuel tank, bomb or missile. A well-designed decoupler pylon can minimize dynamic instability of a wing structure. In this study, it has been demonstrated the effect of passive flutter suppression technique using the decoupler pylon model. A CFD-based TSD code is used to calculate three-dimensional unsteady aerodynamics, and finite element method is applied to the free vibration analysis of the wing-pylon-store structure. The flutter boundaries of the clean wing and wing with decoupler pylon/store are compared in this paper. Also, the effects of structural parameters of decoupler pylon have been studied.
Static Aeroelastic Analysis of Hingeless Rotor Blades in Hover Using Euler Equations
Choi, Ji-Hoon ; Jeon, Seong-Min ; Kwon, Hyuk-Jun ; Lee, In ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 56~56
The static aeroelastic characteristics of hingeless rotor blades in hover are investigated using Euler equations. Finite elements based on a large deflection beam theory are used for structural analysis. A three-dimensional flow field of a helicopter rotor in hover is calculated by using Euler equations described in a body-fixed rotating coordinate frame. No wake modeling is included but the wake is calculated as a part of the solution of the overall flow field. Comparison of the numerical results in the subsonic and transonic region show good agreements with the experimental data. Numerical results of the steady-state deflections for the rotor blade are presented and compared with those based on the panel method. The difference between two results increases as the collective pitch angle increases. It is found that the aerodynamic wake dynamics effect plays an important role in steady-state tip deflections for the hingeless rotor blades in hover.
Development of an Advanced Structural Model for Composite Beams with Arbitrary Section Shapes
Jung, Sung-Nam ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 65~65
In this paper, a refined structural model, which is an extension of the Vlasov theory, is developed for the analysis of composite beams with bending-torsion and extension-torsion couplings. A comprehensive analysis applicable to both thick- and thin-walled composite beams, Which can have either open- or closed profile is formulated. The theory accounts for the effects of elastic couplings, shell wall thickness, warping, warping restraint, and transverse shear deformations. Reissner's semi-complimentary energy functional is used to derive the beam force-displacement relations. The bending and torsion related warpings are obtained in closed form through the current beam formulation and result in the shear correction factors. The resulting theory describes the beam kinematics in terms of the axial, flap and lag bending, flap and lag shear, torsion and torsion warping deformations. The developed theory is validated against experimental results for various cross-section beams with anisotropic couplings.
Design Optimization of Piezoelectric Sensor/Actuator for Structural Vibration Control
Kim, Ji-Chul ; Park, Keun-Young ; Ryou, Jung-Kyu ; Hwang, Joon-Seok ; Kim, Seung-Jo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 73~73
Distributed piezoelectric sensor and actuator have been designed for the active vibration control of beam and plate structures. Piezoceramic and piezofilm are used as the materials of sensor/actuator. Design method based on the finite element analysis has been developed for the optimization of sensor and actuator systems integrated in the structures. The objective of sensor design is sensing certain modes selectively and preventing the spillover. Actuator design is based on the criterion of minimizing the system energy in the control mode under a given initial condition. In the vibration control of beam structure, the electrode shape of piezofilm sensor and the placement of piezoceramic actuators are optimized. And in the case of plate structure, the electrode patterns of piezofilm sensor and actuator are optimized. Genetic algorithm, sequential quadratic programming and simplex search method are used in the optimization process. Discrete LQG control law has been applied to the integrated structure for the real time vibration control. Performances of designed sensors and actuators are demonstrated by experiments.
Ground Based Attitude Determination Techniques for Koreasat 1,2
Yoon, Jin-Won ; Park, Bong-Kyu ; Bang, Hyo-Choong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 87~87
Momentum Biased System is adopted as an attitude control system of Koreasat 1,2. Roll/pitch angles we measured by an Earth sensor, while other attitude data are not directly measured. Based upon kinematic coupling effect between momentum wheel and orbit rate, the other attitude data that are not measured can be estimated. In this research, nonlinear attitude dynamics of Koreasat 1,2 are derived and attitude estimation software using the Extended Kalman Filter are implemeted and tested by using the simulation data. In this way the attitude data not measured for a geosynchronous satellite using momentum biased system can be shown to be estimated in real-time.
Handling Qualities Analysis in Flight Control
Lim, Sang-Soo ; Youn, Il-Joong ; Lee, Gun-Myung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 97~97
This paper presents the design method of the Fly-By-Wire flight control law based on computer simulation and the concept of equivalent low order analysis for He aircraft having high order characteristics. The F-16 experimental wind tunnel test data were used to develop the design of flight control law. The flight control law design is limited in longitudinal axis and the stability augmentation system(SAS) is applied to augment the aircraft stability and control augmentation system(CAS) for providing output(
) with excellent flying qualities. Deficiencies in flying qualities must be correlated with properties of the control laws and the control law design must be revised many times during the piloted simulation studies and the flight test program. Equivalent low order transfer function provides the measure of a qualitative aircraft handling quality based on simplifying the complicated high order transfer function. The first goal of this work is to correlate relationship between the various gains and the aircraft characteristics as the modal parameters are analyzed and second one is to decide the value of gains to provide a useful guide to design the flight control law of modem highly augmented aircraft for design engineers.
Trajectory Optimization of KOMPSAT Launch Vehicle Using Nonlinear Programming
Roh, Woong-Rae ; Kim, You-Dan ; Lee, Sang-Ryool ; Kim, Hak-Jung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 106~106
Trajectory optimization of launch vehicle which maximizes the payload mass and satisfies the KOMPSAT mission requirements as well as the flight constraints is performed. The vehicle is assumed to be a point mass flying in 3-dimensional space, and the rotating spherical Earth model is used. The control variables of the angle of attack and side slip angle are parametrized and the solutions of optimization problem are determined by nonlinear programming. The designed trajectory of the launch vehicle is maximizing the payload mass to the given mission orbit while satisfying the flight constraints of vertical lift-off, kick-turn, and gravity-turn during the 0th stage, and dogleg yaw maneuver during the
Development of Real-time SNUDGPS via Ionospheric and Tropospheric Corrections
Yun, Doo-Hee ; Kee, Chang-Don ; Kim, You-Dan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 115~115
In conventional DGPS, ionospheric and tropospheric spatial de-correlation degrades the positioning accuracy if the user is away from the reference station more than 100km. So, the coverage of DGPS reference station is limited within about 100km. This is also true for time transfer and Wide Area Differential GPS (WADGPS). In the years around 2000, when ionosphere activity is expected to be peak and also if we consider that the S/A may be turned off, ionospheric time delay will be the biggest and the major positioning error source. With that in mind, we have developed an advanced DGPS, whose name is SNUDGPS(Seoul National University DGPS). The SNUDGPS can compensate both the ionospheric and tropospheric delays using, what so called, local area ionospheric time delay model and conventional troposphere model. As a results, not only the coverage of the reference station can be extended more than 100km, but also the positioning accuracy can be improved. This paper introduces the concept of SNUDGPS and implements the SNUDGPS as real-time system using sequential type parameter estimation filter for the local area ionospheric time delay model.
A Study on Searching Speeds of Real-time Searching Algorithms
Yoon, Sug-Joon ; Kang, Hyun-Joo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 126~126
Various parameter values are provided in the form of tables, where data keys are ordered and unevenly spaced in general, for real-time simulation of dynamic systems. Unit intervals including parameter values are searched rather than stored data keys. Since real-time constraint enforces use of a fixed step size in integration of system differential equations because of the inherent nature of input from and output to real hardware, the worst case of iterated probes in searching algorithms is the core measure for comparison. In this study, contentional Bisection, Interpolation, and Fast searches are analyzed and compared in the worst cases, Big O's, as well as the newly developed searching algorithms: Modified fast search and Modified regular falsi search. The numerical tests show that Modified regular falsi search is faster than the other interpolation searches in either expected time or worst case. In the case of non-linear data distribution, Bisection search turns out to be superior to Interpolation search and its derivatives. But, the logic reverses for linear or near linear data distribution because interpolation searches locate key values at once.
Numerical Study on NOx Emission of Hydrogen-Air Flame with Coaxial Air
Kim, Seong-Lyong ; Sim, Hyung-Seok ; Jeung, In-Seuck ; Yoon, Young-Bin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 133~133
A numerical analysis using the quasi-laminar reaction modelling has been performed to analyze the thermal NOx formation of turbulent nonpremixed hydrogen-air flames with coaxial air. Here, quasi-laminar reaction modelling calculates the reaction rate with mean temperature and mean species. For convergence acceleration, the preconditioning method is used with the detailed nonequilibrium chemistry. The results show the experimentally observed one-half power dependence between EINOx/flame residence time (
) and the global strain rate (
). In simple jet turbulent flames, it is generally known that one-half power dependence is mainly attributed to nonequilibrium reactions, radiation and buoyancy. However the present analysis show that there may be another factor for the one-half power dependence of coaxial air flame: the variation of flame shape and reaction zone thickness where NOx formation occurs.
An Experimental Study on the Breakup Characteristics of the Liquid Sheet Formed by Impinging Jets
Han, Jae-Seob ; Kim, Seon-Jin ; Park, Bong-Yeop ; Kim, Yoo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 142~142
The breakup characteristics of liquid sheet formed by the liquid rocket injector has a close relation with the combustion instability. In this paper, basic characteristics of liquid sheet was measured with instantaneous image of the spray cone and PDPA for the Like Doublet Impinging Injector. Test variables were the angle of impact, the diameter of orifice and jet velocity. Water was used as test fluid. Experimental results show that the breakup length of liquid sheet is increased with increasing orifice diameter. For Impingement angle, breakup length is decreased up to
, then is increased for Impingement angle more than
. When jet velocity changes, there exist two conflicting field which depends on the inertial force and the balance of surface tension. It was also found that breakup frequency increased with decreasing angle of impact and with increasing jet velocity The liquid sheet velocity which is the most important parameter for the breakup frequency can be expressed as a function of half angle of fuel and oxidizer jet(
A Study on the Conceptual Design of a Stratosphere Airship and Entry Simulations to the Mission Altitude
Park, Choon-Bae ; Song, Seung-Uk ; Kim, Myong-Sung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 149~149
In this paper, a conceptual design procedure for a stratosphere airship which will be used as a cellular phone relay is proposed. The design method of a stratosphere airship with a very large air bag and photoelectric cells as the energy source must be differ from that of a conventional low altitude airship. In this paper a new design method which is the iteration procedure by convergence check based on the area of photoelectric cells and the size of air bag for the given maximum available power and payload as the design requirements. A technology demonstrator and a operational airship are designed by this method. And the sensitivity analyses are conducted for the changes of design requirements and design parameters. The entry simulations to mission altitude are conducted to check the feasibility of a stratosphere platform. The climb procedures are simulated as a stratosphere airship is in the real atmospheric condition to consider the way to reach to the mission altitude. The time to climb and the horizontal miss distances are calculated.
Power Analysis for Koreasat-3 Solar Array
Ma, Keun-Su ; Choi, Sung-Bong ; Kim, Yang-Mo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 158~158
In this research, the power analysis program that can be used to generate I-V and P-V curve of Koreasat-3 solar array by taking into account charged particles as well as factors affecting solar array power and using analytical solar cell model is developed using MATLAB. Using this program, the generated power capacity of the solar array can be more precisely estimated with telemetry data at any specific time during whole mission life. So, it can be valuable tool for optimum operating and monitoring of Koreasat-3 system. Also, it can be used to analyze the Koreasat-3 electrical power subsystem including solar array source.
Gas Turbine Engine Components and System Performance Test Facilities in KARI
Lee, Dae-Sung ; Cha, Bong-Jun ; Han, Yeong-Min ; Yoon, Min-Soo ; Kim, Chun-Tak ; Ko, Young-Sung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 28, issue 1, 2000, Pages 166~166