• Journal of Welding and Joining
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• v.28 no.2
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• pp.74-78
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• 2010

In this paper, a non-contact method of evaluating the thickness reduction in an aluminum sheet caused by corrosion and friction using SH-EMAT (shear horizontal, electromagnetic acoustic transducer) is described. Since this method is based on the measurement of the time-of-flight and amplitude change of guided waves caused from the thickness reduction, it provides information on the thinning defects. Information was obtained on the changes of the various wave features, such as their time-of-flight and amplitude, and their correlations with the thickness reduction were investigated. The interesting features in the dispersive behavior of selected guided modes were used for the detection of thinning defects. The measurements of these features using SH waves were performed on aluminum specimens with regions thinned by 7.2% to 29.5% of the total thickness. It is shown that the time-of-flight measurement provides an estimation of the thickness reduction and length of the thinning defects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.37-46
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• 2014

This paper describes the conceptual design and development test procedure of a unmanned scaled-down personal air vehicle(PAV) with drive and flight dual mode capability. Trade studies on operational requirements led to the suggestion of a quad tilt prop platform which has nacelle tilt capability with multi rotor configuration. Motors for propeller propulsion and driving mechanism were integrated into a single nacelle, then they were implemented by nacelle tilt mechanism for conversion between the drive and the flight modes. Primary design parameters and initial specifications were confirmed through conceptual design, then functional tests were performed with the test platforms for the drive and the flight modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.22-31
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• 2005

A design study was conducted for a new concept aircraft(Canard Rotor/Wing: CRW) that has the capability of dual mode flight, a rotorcraft and a fixed wing mode. The CRW can show a vertical take off/landing and a high speed/efficiency cruise performance simultaneously. It is not surprising to develop a new sizing code for this class of aircraft because conventional sizing codes developed solely for either the rotary wing or the fixed wing aircraft are not adequate to design a dual mode aircraft operated both by the rotary wing through tip jet effux and the fixed wing lift. Thus, a new design code was developed based on the conventional sizing code by adding some features including rotor performance, duct flow, and engine flow analysis, hence could eventually predict the performance of reaction driven rotor, the flight performance and the flight characteristics. The various design parameters were investigated to find their influences on the flight performance then, a small UAV(Unmanned Aircraft Vehicle) of 1500 lbs class was optimally designed to have minimum weight using the developed sizing code.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.83-90
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• 2008

The next generation LID satellite has 64KB PROM which contains the boot loader and the monitor software, and two 4MB NVMEMs which are used for flight software storage. The boot loader has two operation modes which are the flight software mode and the monitor mode. In the flight software mode, it checks CRC checksum of selected NVMEM and copies flight software image from NVMEM to RAM And then it starts VxWorks RTOS in RAM, creates flight software tasks, and starts execution of flight software. In the monitor mode, it activates monitor software which performs NVMEM reprogramming and board-level testing on the ground. This paper is to present the design of Boot ROM software and verification method using simulator.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.857-866
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• 2022

Fixed-wing UAVs have long endurance and range capabilities compared to other aerial platforms. These advantages led fixed-wing UAVs to become a popular platform for reconnaissance missions in the military. In this research, we modeled fixed-wing UAVs, including the landing gear model and developed a guidance and control system for flight control computers to construct a HILS environment. We also developed an autopilot system that includes automated take-off, cruise, and landing control for UAVs. We also retrived the Aerodynamic coefficients an UAV using Datcom and AVL software and used them for 6 degrees of freedom modeling. The Flight control computer calculates guidance commands using the Carrot chasing guidance law after distinguishing the condition of the UAV based on 16 pre-defined flight modes and calculates control inputs using Nonlinear Dynamic Inversion (NDI) control scheme. We used RTNngine to integrate the Simulink model and flight control computer for HILS environment formulation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.3
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• pp.7-14
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• 2008

In modern aircraft, an autopilot system is getting more important. There are not many autopilot systems applied to small aircraft. Also the autopilot system in large or medium aircraft is difficult to apply to small aircraft directly. It is necessary to make a new autopilot system for small aircraft. In this paper, we implement the small aircraft simulator with autopilot system using SIMULINK. The various modes of autopilot - such as altitude select/hold, attitude hold, heading hold, etc. - are implemented to the flight simulator and tested. We also implement the VOR mode for aircraft guidance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.581-585
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• 2009

In this study, conceptual design of the RBCC (Rocket Based Combined Cycle) engine was performed for the hypersonic propulsion system development. For the flight mission, RBCC engine takes off at sea level and accelerates up to Mach 8 at the altitude of 30km. By the flight speed characteristics, operating pattern of the engine is categorized into 3 modes : Ejector jet (~Mach 3), Ramjet (Mach 3~6), Scramjet (Mach 6~8). According to the engine mode characteristics, RBCC engine design and analysis was performed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.173-177
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• 1992

The Helicopter has a lot of flight modes. The most characteristic flight mode is Hovering. It enables the helicopter to be used in many situations. However, a helicopter has nonlinear dynamics so its mathematical modeling is very difficult. Hence it is not easy to control helicopter in hover. In this paper, RC model helicopter is selected as a plant. To stabilize the behavior of RC model helicopter, Fuzzy alogrithm is used as a controller and one camera is used as a sensor. To get proper Information from camera Image, three characteristic points are attatched to the helicopter and a position recognition algorithm is developed. Experiments are performed to stabilize 3 rotational motions synchronousely with fuzzy control algorithm. As a result, Fuzzy control represents better performances than the conventional PID control.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.10-17
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• 2001

In this paper are presented main power and gasdynamic characteristics of hypersonic test cell of Research Test Center (RTC) of Central Institute of Aviation Motors (CIAM). The distributions of temperature and Mach number at the exit of the aerodynamic nozzle of test cell are received at simulation conditions of flight at Mf=6. Values of available pressure difference and throttling characteristics for various operational modes of test cell, including the loading of working section by Scramjet model without the heating of air at entrance to the aerodynamic nozzle and with the heating of air, are received too.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.24-32
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• 2007

In this study, computational structural vibration analyses of a smart unmanned aerial vehicle (SUAV) with tilt-rotors due to dynamic hub loads have been conducted considering detailed supporting structures of installed equipments. Three-dimensional dynamic finite element model has been constructed for different fuel conditions and tilting angles corresponding to helicopter, transition and airplane flight modes. Practical computational procedure for modal transient response analysis is successfully established. Also, dynamic loads generated by rotating blades and wakes in the transient and forward flight conditions are calculated by unsteady computational fluid dynamics technique with sliding mesh concept. As the results of present study, transient structural displacements and accelerations of the vibration sensitive equipments are presented in detail. In addition, vibration characteristics of structures and installed equipments of which safe operation is normally limited by the vibration environment specifications are physically investigated for different flight conditions.