• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.16-24
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• 2012

In this study, two-stage hypersonic scramjet vehicle was designed for the flight condition of Mach number 6. In order to launch at sea level, two stage concept was applied. The first stage of the vehicle is solid rocket-powered and is mounted under the second stage. The second stage is powered by scramjet propulsion system and gas wings. The suggested mission scenario is to deliver 0.2 ton payload to the range of 2,000 km. For the first step of conceptual design, trajectory of air vehicle was calculated by 3-DOF trajectory code. Based on the result of trajectory code, scramjet engine design and mass estimation were performed by non-equilibrium nozzle flow code and NASA's HASA model, respectively. In order to find best solution, all steps of designing process was iterated until they was reached.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.14-21
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• 2006

The unsteady vortex lattice method is used to model twisting and flapping motions of a rectangular flat plate wing. The results for plunging and pitching motions were compared with the limited experimental results available and other numerical methods. They show that the method is capable of simulating many of the features of complex flapping flight. The lift, thrust and propulsive efficiency of a rectangular flat plate wing have been calculated for various twisting angles and reduced frequency with an amplitude of flapping angle($20^{\circ}$). And the effects of the twisting on the aerodynamic characteristics of the flapping wing are discussed by examination of their trends.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.160-169
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• 1999

Linear pulse rootor (LPM) be suitable a field where smooth linear rootion of high precision is required, because it's structured with minute teeth pitch in airgap of between and stator and roover(forcer). Force and position of LPM are effected sensitively by the teeth pitch, air gap, permanent magnet and excitation current. So, LPM is much important to analyze the force characteristics. llis paper was awlied to perrreance roothed for force calculation at airgap. The airgap of LPM is maintained from the pressure generated by an air-bearing. Simplified airflow and permeance methods will be used to calculate the air gap under static conditions. Therefore, the maximum available force is then derived using the coenergy method with variable air gap, also normal force and linear thrust was acquired from variable minute displacement 1[mm]. 1[mm].

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.309-317
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• 2011

In this study, two-stage hypersonic scramjet vehicle was designed for the flight condition of Mach number 6. In order to launch at sea level and Mach number 0, two stage concept was applied. The first stage of the vehicle is rocket-powered and is mounted under the second stage. The second stage is scramjet-powered propulsion system and has wing. The suggested mission scenario is to deliver 0.2 ton payload to the range less of 2000km. For the first step of conceptual design, trajectory of air vehicle was calculated by 3-DOF trajectory code. Based on the result of trajectory code, scramjet engine design and mass estimation were performed by non-equilibrium nozzle flow code and NASA's HASA model, respectively. In order to find best solution, all step of designing process was iterated until they were converged.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.124-131
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• 2002

In this study, a preliminary design code was developed for the initiation of HTPB/LOX hybrid rocket system. HTPB was assumed to have a constant regression rate. And initial input parameters; number of port, initial O/F ratio F/W ratio, and chamber pressure, were varied to analyze the effects on the performance and geometry of rocket system. The results showed a qualitatively good agreement with previous data. And it was revealed that there exists a number of design results that meet the mission requirements and that we could find an optimal design case if a proper constraint would be imposed. Thus, it is natural to account for the optimal algorithm during the design procedure and to consider more realistic and reliable formulations used for weight estimation of structural supports and accessories.

• Composites Research
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• v.32 no.4
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• pp.191-198
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• 2019

The basic mechanical properties of helicopter rotor blade are important parameters for the analysis of helicopter performance. However, it is difficult to estimate these properties because the most of rotor blades consist of various materials such as composite materials and metals, etc. In this paper, the bending/torsional stiffness for composite rotor blade of unmanned helicopter were evaluated through experimental and analytical studies. In finite element analysis, the bending/torsional stiffness were evaluated through the relationship of load-displacement and element stiffness matrix. The evaluated stiffness from the measured strains and displacements in bending and torsional test agreed well with the derived results of FEA.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.5
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• pp.39-49
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• 2017

A Space Launch Vehicle (SLV) for Launching Satellites Consists of Multi-stage Rockets for the Purpose of Efficient Flight and Accomplishes the Launch Mission through Flight Events such as Stage Separation, Engine Start and Stop. In this Process, the SLV is Supposed to Undergo the Processes of the Powered Flight Section in which the Engine Generates Thrust and the Ballistic Flight Section in which there is no Thrust Repeatedly. Because it is Difficult to Express these Flight Characteristics of the SLV as a Single Dynamics Model, much Research on Tracking Algorithms using Multiple Models has been Undertaken. In case of using the Multiple Model Tracking Algorithm, it is Expected to Improve the Tracking Performance of the SLV. However, it is Difficult to Select Proper Dynamics Models to be used and the Calculation Amount Increases due to the use of Multiple Models. In this Paper, we Propose a Method to Track the SLV with Diverse Flight Characteristics Efficiently by only Two Kalman Filters using Constant Acceleration Model and Adaptive Singer Model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.609-617
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• 2014

Even though the variable pitch control of a wind turbine blade is known as an effective component for power control over the rated wind speed, it has limited applicability to small wind turbines because of its relatively high cost on the price of small wind turbine. Instead, stall control is generally applied in the blade design without any additional cost. However, stall delay can frequently be caused by high turbulence around the turbine blade, and it can produce control failures through excessive rotational speed and overpowering the electrical generator. Therefore, a passive pitch control module should be considered, where the pitch moves with the aerodynamic forces of the blade and returns by the elastic restoring force. In this study, a method to calculate the pitch moment, torque, and thrust based on the lift and drag of the rotating blade wing was demonstrated, and several effective wing shapes were reviewed based on these forces. Their characteristics will be estimated with variable wind speed and be utilized as basic data for the design of the passive pitch control module.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1087-1096
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• 2011

The purpose of current study is to develop and verify the newly developed solver for analyzing rotor flow using the open-source code. The algorithm of standard solver, OpenFOAM, is improved to analyze the rotor inflow with and without fuselage. For the calculation of the rotor thrust, the virtual blade method based on the blade element method is employed. The inflow velocities on the rotor disk used to specify the effective angle of attack, have been included in the solver. The results of the current rotor inflow analysis are verified by comparing with other experimental and numerical results. It was confirmed that the modified solver provides satisfactory results for rotor-fuselage interaction problem.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.823-832
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• 2014

Displaced non-Keplerian orbit, center of mass is displaced from orbit plane, enables special spacecraft missions. It requires continuous thrust to maintain the orbit, and solar sail is useful for this purpose. Equations for feasible region and stability analysis are derived for non-Keplerian orbit for general continuous thrust. Differences for solar sail spacecraft are discussed. Non-keplerian orbits are classified into four types. Location-specific required accelerations for orbit maintenance are calculated. Orbit stabilities of each orbit type are analyzed and verified by numerical simulations. In order to control non-Keplerian orbit in unstable region, a control algorithm using the real-time LQR control is developed and evaluated by numerical simulations.