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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 25, Issue 6 - Dec 1997
Volume 25, Issue 5 - Oct 1997
Volume 25, Issue 4 - Aug 1997
Volume 25, Issue 3 - Jun 1997
Volume 25, Issue 2 - Apr 1997
Volume 25, Issue 1 - Feb 1997
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Unsteady Transonic Solutions Using Dual Time Stepping
Lee, Seung-Soo ; Park, Min-Woo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 1~1
Unsteady transonic flows are analyzed by a newly developed unsteady Euler solver. This Euler solver uses a high resolution TVD method based on Roe's approximated Riemann solver with the finite volume formulation. Through MUSCL approach, upto the 3rd order of spatial accuracy has been achieved. Dual time stepping is also incorporated into the ADI method to achieve the 2nd order temporal accuracy while reducing the linearization and the factorization errors associated with the ADI method. Numerical results far a pitching airfoil are compared with the published experimental results to demonstrate the accuracy of the method. Results of a three dimensional wing pitching motion are also Presented and compared with the Published experimental results.
Unsteady Aerodynamics Associated with Partial Fling-Clap Motion of the Weis-Fogh Wing
Sohn, Myong-Hwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 14~14
The partial fing-clap motion of the Weis-Fogh wings is investigated tough the simultaneous experimental and numerical method. In the experiment, the surface pressure acting on the two-dimensional wing pair is measured; in the numerical study, the incompressible Navier-Stokes equations are solved far simulating the experimental wing motion and other 3 modelled wing motions. The results analyze qualitatively and quantitatively the vortex-dominated flow and the unsteady fluid dynamic farces generated tv the Weis-Fogh wing pair performing cyclic partial fling-clap motions, based on the data such as the velocity field, the vorticity field, the surface pressure distribution, the lift and the power expenditure.
Computations of the Three-Dimensional Flow Field in a Tube with Sudden Contraction
Kim, Young-Mog ; Oh, Seung-Hyub ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 25~25
Numerical computations of the three-dimensional laminar flow field in a tube with a sudden contraction of cross sectional area, having an inclined angle of 30 deg, were carried out. In this study, the full incompressible Navier-Stokes equations in generalized curvilinear coordinates, using a pseudocompressibility approach for continuity equation, were solved by the implicit, approximately factored scheme of Beam and Warming. Multi-block computational grids of complete continuity at block interfaces were employed. The predicted results for streamwise velocity profiles on validation case with no inclined angle were in very good agreement with the measured data. Computational results showed the nature of complex flow fields within the inclined small tube, including strong pressure-driven secondary flows in the cross stream induced by the effect of streamline curvature. Furthermore, it was found in this study that asymmetric secondary flows were induced in the Reynolds number range above assumed laminar How regime considered. Computed results were also discussed for the topology of such flows.
Wake and Lift-Drag Characteristics of a Bluff Body Covered with Sports Wear
Lee, Bong-Jun ; Yu, Sang-Sin ; Sin, Dong-Jin ; Kim, U-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 35~35
An experimental study has been conducted to determine the wake and lift-drag characteristics of a bluff body covered with various sportswear and the drag reduction effects of riblets engraved on sportswear surfaces to improve the records of speed racing. Wake velocity profile were measured far the bluff body covered with a ski-suit and swim-suit in the low speed wind tunnel. This work also investigate the ability of riblets on the surface of Sportswear to improve the wake and lift-drag characteristics and thereby, produce profile drag reduction for the bluff body. The experimental results showed that the rough surfaces of sportswear modify the turbulent structure and cause a decrease in profile drag in comparison with a smooth surfaces. It is found that riblets on the surfaces of a sportswear is possile to produce a nearly flat wake velocity profile behind the bluff body and increase lift-drag ratio leading to profile drag reduction.
A Study on Back Flow of Impinging Liquid Jets
Park, Jong-Ook ; Cha, Young-Ran ; Kim, Sun-Jin ; Kim, Yoo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 46~46
A experimental study was carried out to investigate the break-up length of back flow and dispersion angle of a liquid sheet formed by impinging injector. Test variables were impingement angle
, orifice diameters (d=0.61, 0.98, 1.56mm) and injection velocities
. Instantaneous images of the sheet were taken by the stroboscope and camera and from the Image both break-up length and dispersion angle were measured. Orifice diameter and injection velocity had little effect on the dispersion angle, but dispersion angle increased with increasing impingement angle. For impingement angle of greater than 60 degree, dispersion angle did not change, but back flow was generated. The break-up length of back flow increased with increasing impingement angle and orifice diameter.
An Improved Closure for the Velocity Triple Moment Based on the Experimental Data
Rew, Ho-Seon ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 53~53
Turbulence models concerning with the triple velocity moment transport were assessed using various experimental data(mean velocity, Reynolds stresses, triple and fourth moments ets.) in the curved wall jet interacting with an opposing curved wall jet. A new model is suggested Previous diffusion model adopting Millionschchikov's zero-foruth-cumultant hypothesis showed good agreement with the experimental data. The models for the sum of the dissipation and the fluctuating pressure transport terms were also compared with the present experimental data. Despite the neglect of the rapid term in the fluctuating pressure transport, Amano et al.'s model generally showed rather good agreement with the experimental data. On the other hand, the model by Dekeyser and launder showed poor agreement with the experimental data because the model constant is Do large. Based on these observations, a new model including rapid term and slow term in the fluctuating pressure transport is suggested. The new model is found to give much better agreement than the previous models with the experimental data.
Optimal Design of Composite Laminates for Maximum Buckling Load
Lee, Jeong-Seok ; Kim, Chang-Wan ; Hong, Chang-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 62~62
An optimization procedure is proposed to determine the optimal stacking sequence of laminated composite plates with midplane symmetry under various loading conditions and aspect ratio. A finite element analysis based on the classical lamination theory has been developed for the determination of the buckling load. Critical buckling load is taken as objective function and fiber orientation is design variable. A series of computation is carried out fer plates having different aspect ratios, load conditions and number of lay-ups. Performance index is introduced to represent the effectiveness of optimal design.
A Study of Optimal Configuration of Piezoelectric Actuators Using Genetic Algorithms
Han, Jae-Hung ; Lee, In ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 71~71
To enhance the controllability of structures, a study on piezoelectric actuator segmentation and actuator patterns has been performed. Separate piezoelectric actuators can be considered as an equivalent single actuator when they are commanded by the same control voltage. After segmenting piezoelectric actuator into an arbitrary number of small pieces, actuator patterns have been effectively determined as a combination of these pieces using Genetic algorithms. It is observed that an actuator pattern fur controlling a particular mode is determined by the phase of modal control forces, Also optimal or neat optimal patterns to control several modes simultaneously by maximizing the centre liability index.
Shape optimization of the distributed piezoelectric sensor/actuator considering the spill-over due to digital control
Park, Keun-Young ; Ryou, Jung-Kyu ; Kim, Seung-Jo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 82~82
This study presents a method for designing the distributed piezoelectric sensor/actuator in digital control environments. Under a given control environment, electrode shape of PVDF sensor/actuator was optimized to maximize the vibration suppression capability. We utilized the finite element method to model the structure integrated with sensor and actuator. The control law incorporated was rate feed-back. To maximize the active damping introduced by the control, the energy dissipated by the passive damping was selected as the performance index to be minimized. Constraints are introduced to get rid of the instability that may come from the discrete sampling and the anti-aliasing filter. Optimized piezo film sensor/actuator was fabricated and assembled with host structure far the experimental demonstration. Experimental results show the better performance of the optimized shape compared to simple modal sensor/actuator.
Integrated Optimization for Optimal Design of Control / Structural System
Kum, Dong-Jun ; Kim, You-Dan ; Nam, Chang-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 92~92
This paper presents an approach for an integrated optimum design of structure and control system. A composite plate with segmented piezoelectric actuators is considered to design control system for vibration suppression. For the design of control system, a robust eigenstructure assignment scheme is adopted. Optimization technique is applied to minimize structural weight as well as control performance indices subject to constraints. The locations of the piezoelectric actuators are considered as control design variables, and the thickness distributions of composite layers are considered as structural design variables. The integrated constraints. design is formulated as a constrained multi-objective optimization problem. The sequential linear programming method with move limit is used. The sensitivity analysis which is required in optimization process is performed for the eigenstructure assignment control scheme and performance indices with respect to the design parameters. Numerical example shows the capability in determining the optimal thickness distributions of the composite layer, and locations of the piezoelectric actuators. The results show the quite amount of reduction in structural weight as well as control performance indices through the optimization.
Development of a Cylindrical Type Piezoelectric Vibrating Gyroscope
Lee, Young-Shin ; Kang, E-Sok ; Kim, Yong-Hwan ; Moon, Hong-Key ; Oh, Jae-Moon ; Byun, Young-Chul ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 106~106
Vibratory gyroscopes have important advantages in comparison with the traditional designed mechanical gyroscopes based on large conservation of angular momentum. There are reasons that they are low power devices and have long operating time with almost instant start-up time and they can be packed into a small working volume far small size of itself. Additional]y, they are low cost, high reliability, and the capability of working in severe environment. In this paper, the feasibility of such a vibratory gyroscope is introduced. The vibration analysis is conducted by ANSYS code. The vibratory piezoelectric gyroscope with control circuit far drive and output pick-off is manufactured and evaluated.
Drag Minimizing Optimal Guidance Laws for Varying Velocity Missiles
Ryoo, Chang-Kyung ; Cho, Hang-Ju ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 117~117
Two optimal guidance laws far missiles with time-varying velocity to intercept a maneuvering targets, derived with the consideration of drag minimization, are studied in this paper. When compared to the case of the control effort minimizing law, the guidance gains are smaller in the first part of the boosting phase and slightly larger in the coasting phase, which could be a desirable property when the maneuver capability in the initial guidance phase is severely limited.
Selection of Initial Frozen Orbit Eccentricity and Evolution of the Orbit Due to Perturbations
Lee, Byoung-Sun ; Lee, Jeong-Sook ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 126~126
An initial frozen orbit eccentricity was calculated using analytical expressions of
terms only. Then the time variations of orbital mean eccentricity and argument of perigee were investigated when the order of the Earth's gravity model was increased from
terms. For the Earth gravity model upto
, an initial frozen eccentricity with the smallest variation was found. The realistic frozen orbit parameter evolution was obtained when various orbital perturbations such as gravitational forces of the Sun and the Moon, solar radiation forces, and air drags were applied.
Error Model of Strapdown Inertial Navigation Systems
Lee, Hyung-Keun ; Lee, Jang-Gyu ; Rho, Young-Kyu ; Park, Chan-Gook ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 133~133
In this paper, we propose a new equivalent tilt angle
which in appears in local-level strapdown inertial navigation systems and derive its error model by the computer frame approach. While the conventional equivalent tilt error model requires complex computation since the attitude error equation is coupled to the position and velocity error equations by the characteristics of the true frame approach, the proposed error model requires more simple computation because the velocity and attitude error equations are decoupled. In this paper, we also define another equivalent tilt angle
which represent the attitude error between the t-frame and the c-frame. By using it, we rove리 the relationship between the error models which are derived by the true frame approach or by the computer frame approach.
Feedback Control Law Design for Dual Spin Turn Maneuver of Spacecraft
Bang, Hyo-Choong ; Kim, Sung-Kyu ; Hwangbo, Han ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 146~146
A new feedback control law design for the Dual Spin Turn(DST) maneuver of spinning spacecraft is discussed in this paper. The control law design study is motivated by the stability analysis of dual spin spacecraft. The nutational stability of dual spin spacecraft which contains a driven rotor is directly related to the so-called core energy of the system. That is, the core energy must decrease in order to guarantee stability. The feedback control law is designed adjust the wheel speed so that the core energy and notation angle may decrease simultaneously. A two stage DST control stratgy which consists of conventional open loop maneuver and a feedback technique is also developed in this paper.
Landing Characteristics of Aircraft with Optimal Anti-Skid Brake
Kim, Du-Man ; Im, Gyeong-Ho ; Hwang, Jae-Hyeok ; Go, Ung-Dae ; Park, Myeong-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 156~156
In this study, landing characteristics of an aircraft with optimal anti-skid brake have been analyzed. When the braking farce is not enough the landing distance increases, while an excessive braking force makes the wheel skid on the runway. Therefore, to obtain the shortest landing distance without skidding, it is necessary to adjust the braking force correspondingly to the frictional force between the tire and the runway. In this research, the optimal braking force is designed and one-step prediction algorithm is suggested to compensate the time lag of brake servo system. It has been found by a series of numerical simulation that the present anti-skid brake system proposed here reduces the landing run remarkably and is robust to runway mean profiles.
Evaluation Methodology for Domestic Aircraft Material
Lee, Ho-Sung ; Shin, Don-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 165~165
In order to design aircraft structures in compliance with airworthiness standard, it is essential to completely characterize the material system which the structure consists of. Simultaneously the compliance of the material properties to the various loading and environmental conditions required fer aircraft design must be proved. This paper provides materials characterization methodology for aircraft application and design allowables far tensile mechanical property of aluminum alloy extrusions produced domestically.
Current Issue and Future Direction of Korean Aerospace Industry
Hong, Chang-Sun ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 177~177
Perspectives of Helicopter Technology and Industry
Joo, Gene ; Lee, Seung-Ri ; Rhiu, Jeoung-Joo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 1, 1997, Pages 181~181