• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.30-41
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• 2001

In Underwater Flight Vehicle depth control system, the followings must be required. First, It needs a robust performance which can get over the nonlinear characteristics due to hull shape. Second, It needs an accurate performance which has the small overshoot phenomenon and steady state error to avoid colliding with ground surface and obstacles. Third, It needs a continuous control input to reduce the acoustic noise. Finally, It needs an effective interpolation method which can reduce the dependency of control parameters on speed. To solve these problems, we propose a Intelligence depth control method using Fuzzy Sliding Mode Controller and Neural Network Interpolator. Simulation results show the proposed control scheme has robust and accurate performance by continuous control input and has no speed dependency problem.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.271-276
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• 1994

In this paper we deal with a design of CCV adaptive flight control system having adaptive observer under the mircroburst circumstances. First, based on the observerbility indices of the controlled system, which is a general multi-variable one, the adaptive observer is constructed, and the unknown interactor matrix can be estimated by using the identified parameters. Next, CCV adaptive flight control law is calculated based upon the estimated ones. Finally, the proposed CCV adaptive flight controller is applied to STOL flying boat and numerical simulations under the microburst circumstances can be show to justify the proposed scheme.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.8
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• pp.367-375
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• 2001

In Underwater Flight Vehicle depth control system, the followings must be required. First, it needs robust performance which can get over modeling error, parameter variation and disturbance. Second, it needs accurate performance which have small overshoot phenomenon and steady state error to avoid colliding with ground surface or obstacles. Third, it needs continuous control input to reduce the acoustic noise and propulsion energy consumption. Finally, it needs interpolation method which can sole the speed dependency problem of controller parameters. To solve these problems, we propose a depth control method using Fuzzy Sliding Mode Controller with feedforward control-plane bias term and Neural Network Interpolator. Simulation results show the proposed method has robust and accurate control performance by the continuous control input and has no speed dependency problem.

• Journal of Powder Materials
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• v.1 no.1
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• pp.85-94
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• 1994

In order to predict droplet velocity and temperature profiles and fractional solidification with flight distance during spray forming, the Newtonian heat transfer formulation has been coupled with the classical heterogeneous nucleation and the specific solidification process. It has been demonstrated that the thermal profile of the droplet in flight is significantly affected by process parameters such as droplet size, initial gas velocity, undercooling. As the droplet size and/or the initial gas velocity increase, the onset and completion of solidification are shifted to greater flight distances and the solidification process also extends over a wider range of flight distances. The amounts of solid fractions formed during recoalescence, segregated solidification and eutectic solidification are insensitive to droplet size and initial gas velocity whereas those are strongly affected by the degree of undercooling. There are good linear relations between the undercooling and the corresponding solid fractions generated during recoalesced, segregated and eutectic stages.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.2
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• pp.58-63
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• 2012

An altitude chamber, also known as a hypobaric chamber, is a device used during aerospace or high terrestrial altitude research or training to simulate the effects of high altitude on the human body. Although data from altitude chamber researches using experimental animals have been accumulated, studies in the humans exposed to hypobaric conditions are seldomly reported. Despite the importance of altitude chamber flight training in the field of aviation physiology, the hematological analysis of post-flight physiological changes has rarely been performed. The aims of the present study were to investigate the alterations in blood components during altitude chamber flight and to determine whether the differences between pre- and post-flight values are significant. Sixty experienced pilots in the Republic of Korea Air Force were enrolled in the altitude chamber flight training. Venous blood samples were obtained before and immediately after the flight. Compared with the pre-flight values($6.32{\times}10^3/mm^3$, $5.02{\times}10^6/mm^3$, 15.61 g/dL, respectively), white blood cell count, red blood cell count and hemoglobin level were significantly increased after the flight($6.77{\times}10^3/mm^3$, $5.44{\times}10^6/mm^3$, 16.26 g/dL; p=0.006, p=0.012, p<0.001, respectively). These alterations may be attributable to the exposure to hypobaric hypoxia, 100% oxygen supply for denitrogenation, considerable rise and fall in altitude and psychophysical stress due to these factors. In further studies, experimental groups and methods should be individualized to ensure objectivity and diversification. In addition, multiple time-frame analyses regarding the changing pattern of each blood component are also required to elucidate the physiological process for adapting to the high terrestrial altitude exposure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.927-934
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• 2011

Design parameter analysis is performed for a solar-powered UAV, storing potential energy by climb flight. Parameters related to the flight for saving potential energy, i.e. minimum & maximum altitudes for level flight, gliding & climbing angle, design point speed & altitude, gliding & climbing start time are investigated as design parameters. Weight and size of the UAV are determined using a weight model for the components of the solar-powered UAVs. Produced energy and consumed energy are calculated using these weight and size, yielding the required weight of the battery for a given mission. Relationship between the total weight of the UAV and each parameter is investigated. For the parameters listed above, there exist their ranges only where the design is possible. And there exist optimal values of these parameters minimizing the total weight.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.506-514
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• 2012

This paper represents a method for designing of path following Line-of-Sight(LOS) guidance law based on vehicle kinematics. In general, a LOS guidance law which is composed of gains and approach length as design parameters is designed by empirical or trial-and-error method. These approaches cannot guarantee a precision tracking performance of guidance law consistently. Also, the design parameters should be redesigned with variations of vehicle maneuverability and flight velocity. Based on a vehicle kinematics with its velocity, the proposed method for designing of parameters not only minimizes the number of design parameters, also has a reliable and consistent tracking performance using variable guidance gain changed in accordance with flight velocity. This is validated by nonlinear simulation with $1^{st}$ order attitude response dynamics and flight experiments with given linear and circular path.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.995-1000
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• 2004

A digital adaptive flight control system is presented for a Japanese automatic landing flight experiment vehicle (ALFLEX). In previous adaptive control systems based on a linear-parameter-varying (LPV) form, the output behavior was excellent, while the behavior of the adjusted parameters was unsatisfactory. In the present study, to obtain a more appropriate parameter adjustment law, the relationship between the coefficient matrices in a continuous-time state equation and the coefficients of a pulse transfer function in a discrete system for conventional aircraft is investigated. As a result, it is revealed that the coefficients of the numerator can be treated as a linear function of dynamic pressure (linear-parameter-varying: LPV), while the coefficients of the denominator can be treated as constant (linear-time-invariant: LTI). From the above analysis, an improved parameter adjustment law is derived by reducing the number of the adjustment parameters. Simulation results also revealed both good output tracking and good parameter adjustment compared with the previous results.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.688-696
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• 2017

This paper presents an integrated roll-pitch-yaw autopilot using an equivalent based sliding mode control for skid-to-turn nonlinear time-varying missile system with lumped disturbances in its six-equations of motion. The considered missile model are developed to integrate the model uncertainties, external disturbances, and parameters perturbation as lumped disturbances. Moreover, it considers the coupling effect between channels, the variation of missile velocity and parameters, and the aerodynamics nonlinearity. The presented approach is employed to achieve a good tracking performance with robustness in all missile channels simultaneously during the entire flight envelope without demand of accurate modeling or output derivative to avoid the noise existence in the real missile system. The proposed autopilot consisting of a two-loop structure, controls pitch and yaw accelerations, and stabilizes the roll angle simultaneously. The Closed loop stability is studied. Numerical simulation is provided to evaluate performance of the suggested autopilot and to compare it with an existing autopilot in the literature concerning the robustness against the lumped disturbances, and the aforesaid considerations. Finally, the proposed autopilot is integrated in a six degree of freedom flight simulation model to evaluate it with several target scenarios, and the results are shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.546-551
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• 2001

Space Test Department at KARI(Korea Aerospace Research Institute) plans to carry out the GVT(Ground Vibration Test) for the KSR(Korea Sounding Rocket)-III FM(Flight Model) which is being developed by Space Technology R＆D Division. KSR-III will be an intermediate to the launch vehicle capable of carrying satellites to their orbits. GVT offers very important information to predict the behavior of KSR in its operation, and to develop the flight control and aerodynamic analysis. For development of test facilities, testing and analysis methods which can be used for the future test, Space Test Department has performed the GVT with KSR-II PFM(Proto-Flight Model) at Satellite Integration ＆ Test Center of KARl This paper discusses the procedures, techniques and the results of it. In this test, to simulate free-free condition, test object hung in the air by 4 bungee cords specially devised. The GVT was carried out using pure random excitation technique with MIMO(Multi-Input-Multi-Output) method with three electromagnetic shakers, and poly-reference parameter estimation was used to identify the modal parameters. As the result of the test, 11 mode shapes and modal parameters below 200㎐ were identified and compared with analytical results.