• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.601-609
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• 2014

Large number of SAR(Synthetic Aperture Radar) satellites, one type of earth observation satellite, have been developed as they have the advantage of not being affected by surrounding environment during the earth image acquisition. In order to gain high image quality, SAR antenna should have large diameter. However, internal space of satellite launch vehicle is limited and this leads SAR antenna to be designed deployable so that it can be folded in launch vehicle and unfolded in space. In this research, values of various design factors of deployable satellite antenna were chosen considering satellite's target mission. Configuration of deployable satellite antenna was designed by applying the chosen values of design factors, and variation in deployable satellite antenna during satellite maneuver was observed through simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.807-815
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• 2008

In this paper, design, development and evaluation of DIP(Database Interface Program) are presented. The main purpose of this study is to improve the simulation quality to get more realistic response of target system. The designed and developed major function is composed of flexible memory structure, efficient arithmetic database language and high speed interpolation/extrapolation algorithm. To evaluate the operation speed and accuracy of returned data, trim simulation is performed based on in-house software and, DIP is applied to existing real-time simulator such as engineering HQS(Handling Quality Simulator) to evaluate reliability and performance. The result of evlaution reveals that calculation speed and data accuracy are satisfied, and flight performance is satisfied in the real-time simulator environments.

• Journal of Astronomy and Space Sciences
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• v.27 no.3
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• pp.195-204
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• 2010

The optimal Earth-Moon transfer trajectory considering spacecraft's visibility from the Daejeon ground station visibility at both the trans lunar injection (TLI) and lunar orbit insertion (LOI) maneuvers is designed. Both the TLI and LOI maneuvers are assumed to be impulsive thrust. As the successful execution of the TLI and LOI maneuvers are crucial factors among the various lunar mission parameters, it is necessary to design an optimal lunar transfer trajectory which guarantees the visibility from a specified ground station while executing these maneuvers. The optimal Earth-Moon transfer trajectory is simulated by modifying the Korean Lunar Mission Design Software using Impulsive high Thrust Engine (KLMDS-ITE) which is developed in previous studies. Four different mission scenarios are established and simulated to analyze the effects of the spacecraft's visibility considerations at the TLI and LOI maneuvers. As a result, it is found that the optimal Earth-Moon transfer trajectory, guaranteeing the spacecraft's visibility from Daejeon ground station at both the TLI and LOI maneuvers, can be designed with slight changes in total amount of delta-Vs. About 1% difference is observed with the optimal trajectory when none of the visibility condition is guaranteed, and about 0.04% with the visibility condition is only guaranteed at the time of TLI maneuver. The spacecraft's mass which can delivered to the Moon, when both visibility conditions are secured is shown to be about 534 kg with assumptions of KSLV-2's on-orbit mass about 2.6 tons. To minimize total mission delta-Vs, it is strongly recommended that visibility conditions at both the TLI and LOI maneuvers should be simultaneously implemented to the trajectory optimization algorithm.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.206-212
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• 2017

Induction motor torque is the reactive power is needed which corresponds to the exciting current to generate the magnetic flux as the product of current and flux. For use in the method of supplying the required reactive power to the induction motor power factor correction apparatus using a lot of ways to supply in place of the power supply side, when using a power factor compensation device can reduce the apparent power, the power factor can be improved. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.3
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• pp.221-226
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• 2012

This research presents an analysis of algorithm for ship track-keeping along a given trajectory. The maneuver of a free running model ship guiding through a simple path are presented. In order to solve the above problem, a desired trajectory is usually determined by GPS points in a pre-fixed place then these points are set in a pre-programmed navigation so that the ship would be automatically tracked. Proportional-Derivative(PD) control which is useful for fast response controllers was used in this program as a course keeping system. A high accuracy GPS receiver was installed on the model ship that could provide positions frequently, the system will compare and give out the remaining distance and heading to the target way-point. The results of ship auto track-keeping experiment will be explained in order to illustrate the adjustment in controlling parameters. These results can be utilized as a preliminary step to carry out the experiment of ship collision avoidance system and automatic berthing in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.28-35
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• 2009

This paper derives the equation of coordinated attitude formulation taking into account the orbital dynamics of a target vehicle and the attitude of a tracking satellite in geostationary orbit. The coordinated attitude is always to communicate with the ground station during the target tracking. Because the tracking satellite could perform high angle maneuver, MRP parameters having no singular point are used. Also for the sequential tracking of several target vehicles, the equation automatically making a coordinated attitude is suggested. Coordinated attitude flying and sequential tracking are confirmed through simulations. In short, this paper shows that a satellite could track a target vehicle and communicate with ground station simultaneously using the derived equation of coordinated attitude even though without a accuracy sensor.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.27-34
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• 2014

Buzz margin scheduling and control technique which are suitable to regulate stable and high pressure air in wide range of Mach number are suggested for fixed geometry of a supersonic intake. From the analysis of preceding study, most effective control variable is induced and scheduling law is newly suggested in a real application point of view. The appropriateness of the control law in wide range of Mach number is addressed by numerical simulation of controlled propulsion system. Also, the simulation for stabilization and tracking performances of the controller are studied to investigate the phenomena under flight maneuver and disturbances.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.3
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• pp.199-212
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• 2014

This paper describes an autonomous air combat guidance law using a Virtual Pursuit Point (VPP) in one-on-one close engagement for Unmanned Combat Aerial Vehicle (UCAV). The VPPs that consist of virtual lag and lead points are introduced to carry out tactical combat maneuvers. The VPPs are generated based on fighter's aerodynamic performance and Basic Fighter Maneuver (BFM)'s turn circle, total energy and weapon characteristics. The UCAV determines a single VPP and executes pursuit maneuvers based on a smoothing function which evaluates probabilities of the pursuit types for switching maneuvers with given combat states. The proposed law is demonstrated by high-fidelity real-time combat simulation using commercial fighter model and X-Plane simulator.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.711-719
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• 2008

Although non-real time simulation and pilot based evaluations are available for the development of flight control computer prior to real flight tests, there are still many risky factors. The control law designed for prototype aircraft often leads to degraded performance from the initial design objectives, therefore, the proper evaluation methods should be applied such that flight control law designed can be verified in real flight environment. The one proposed in this paper is IFS(In-Flight Simulator). Currently, this system has been implemented into the F-18 HARV(High Angle of Attack Research Vehicle), SU-27 and F-16 VISTA(Variable stability. In flight Simulation Test Aircraft) programs. This paper addresses the concept of switching mechanism for FLCC(Flight Control Computer)-SWMC(Switching Mechanism Computer) using 1553B communication based on flight control law of advanced supersonic trainer. And, the fader logic of TFS(Transient Free Switch) and stand-by mode of reset '0' type are designed to reduce abrupt transient and minimize the integrator effect in pitch axis control law. It hans been turned out from the pilot evaluation in real time that the aircraft is controllable during the inter-conversion process through the flight control computer, and level 1 handling qualities are guaranteed. In addition, flight safety is maintained with an acceptable transient response during aggressive maneuver performed in severe flight conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.98-110
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• 2015

Recently, a validation research of maneuvering and attitude control logics of a spacecraft under a ground condition is getting increase by using operating simulators with compact and precise components. For that, a cold gas propulsion system is generally used for maneuvering and attitude control of spacecraft ground simulators for its simplicity and a high reliability. In the present study, major design parameters of a cold gas propulsion system are derived to meet mission requirements based on conceptual design results of a simulator. And additionally, commercial components with proper specifications are selected for system assembly.