• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.7 no.1
• /
• pp.1-9
• /
• 1982

This study, noting the provisions of the complete revision of the International Frequency Administration System, mainly frequency allocations of the Broadcasting Service and the Broadcasting-Satellite Service forming part of the World Radio Administrative Conferences, 1979, bearing in mind the development of International Frequency Administration System and international trends, with a view to attempting the effective utilization of frequencies which may be adapted for those plans of the service in the future, is analysed and considered on the points and improvement of frequency allocations.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.14 no.1
• /
• pp.22-27
• /
• 2006

The linear and nonlinear aeroelastic analyses of a flat plate wing with flaperon have been performed by using frequency-domain and time-domain analyses. Natural modes from free vibration analysis and a doublet-hybrid method (DHM) are used for the computation of subsonic unsteady aerodynamic forces. The flaperon hinge is represented by a free-play spring and is linearized by the described function method. The linear and nonlinear flutter analyses indicate that flapping mode of the flaperon, the hinge stiffness and free-play of hinge have significant effects on the aeroelastic characteristics. From the nonlinear flutter analysis, different modes like stable and unstable limit-cycle-oscillation are observed in same flutter velocity depending on initial conditions.

• IE interfaces
• /
• v.20 no.3
• /
• pp.298-308
• /
• 2007

Radio Frequency Identification (RFID) is one of Identification Technologies today. Many of the large retailers in the United States and Europe have established requirements for their suppliers to use RFID technology in 2004. Recently Airbus and Boeing have announced plans to develop a single RFID specification to be used by both companies to use RFID tags to identify commercial aircraft parts. However, it does not mean the end of barcode and it may take several years before the wide adoption of the RFID. This is because a precise business process reengineering is required with technology itself to get the potential benefits of RFID. In this paper, we introduce an RFID enabled air baggage handling process which has been developed and tested recently. We believe our study would give a good guideline for further researches on RFID application in the aviation industry.

• Journal of Mechanical Science and Technology
• /
• v.15 no.6
• /
• pp.743-751
• /
• 2001

A Prototype reaction wheel, named the Hankuk Aviation University (HAU) reaction wheel, has been developed for KAISTSAT satellite series. Torque and force disturbances are inherent in reaction wheels, and thus the force and torque characteristics should be examined for every newly developed reaction wheel. The torque and force disturbance noises in the prototype HAU reaction wheel are measured with a torque-measuring table developed for the present study. A new measuring procedure based on a simple principle is applied for the measurements. The frequency characteristics of the torque and force noises are analyzed by examining the power spectral density. The effect of the torque noise on the attitude stability is also examined through numerical simulations with a single-axis attitude model. The noise-induced attitude error and jitter and found to be well below the specified error limits for the KAISTSAT satellite series.

• Journal of information and communication convergence engineering
• /
• v.1 no.4
• /
• pp.194-198
• /
• 2003

Recently, the use of TCP/IP protocols over wireless LANs poses significant problems. In this paper, we have analyzed transmission control protocol (TCP) packet transmission time for mobile IP over wireless local area networks (LANs) using a proposed a new random backoff scheme. We call it as a proxy backoff scheme. It is considered the transmission time of TCP packet on the orthogonal frequency division multiplexing (OFDM) in additive white gaussian noise (AWGN) channel. From the results, a proposed proxy backoff scheme produces a better performance than an original random backoff in mobile IP over wireless LANs environment. Also, in OFDM/quadrature phase shift keying (QPSK) medium access control (MAC), we have obtained that the transmission time in wireless channel decreases as the TCP packet size increases.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.398-402
• /
• 2003

In this paper, we have analyzed the performance enhancement of OFDM/QPSK-DMR(Orthogonal Frequency Division Multiplexing/Quadrature Phase Shift Keying Modulation-Digital Microwave Radio)system using BL-PSF(Band Limited-Pulse Shaping Filter) over the microwave channel. For performance enhancement, we apply the one-tap adaptive equalizer for OFDM/QPSK-DMR system and compare with the BER performance of single carrier DMR system. Computer simulations confirm that the OFDM/QPSK-DMR system using one-tap adaptive equalizer has the same BER performance for the single carrier DMR system.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.21 no.1
• /
• pp.15-22
• /
• 2013

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.12 no.2
• /
• pp.43-58
• /
• 2004

Up-to-date cargo transport system, CVO(Commercial Vehicle Operations) is the system to manage efficiently cargo distribution as providing at real time the information of cargo location and situation through ITS and GPS technology. In this paper, we proposed the Gate Automation System of harbors among AEI/AVI. To implement his system, we use the DSRC/RFID(Dedicated Short Range Communication / Radio Frequency IDentification) which adopts an wireless communication between RSE(Road-side Equipment) and OBE(on-Board Equipment) on a vehicle. When constructing the Gate automation system of harbors, the business application ability are reviewed practically and the logistics facilities to be constructed in the near future may use this project results according to the international standard and it could help complete integrated logistics system.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.15 no.3
• /
• pp.24-32
• /
• 2007

In this research, using Terfenol-D actuator composed of magnetostrictive material as shaker and controller, active vibration control theory was applied and verified by experiments. PPF(positive Position Feedback) algorithm which is effective for the control of low frequency vibration was used for the control of a structure. Responses of inputs due to various design variable used for the PPF filter were observed. To investigate the characteristics of magnetostrictive materials, actuator responses were measured for known inputs and satisfactory results were obtained to reduce the vibration level after applying the control input for the actuator.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.15 no.3
• /
• pp.6-14
• /
• 2007

In this research, vibration reduction and aeroelastic stability of a composite hingeless rotor hub flexure with viscoelastic constrained layer damping treatment(CLDT) were investigated. The composite flexures with viscoelastic CLDT were applied to hingeless rotor system to improve the in-plane stability of the lead-lag motion causing resonance. The modal test was performed and dynamic properties(natural frequency and loss factor) were acquired. Also, complex eigenvalue analysis(SOLlO7) in the NASTRAN structural analysis module was performed and compared with results of the modal test. To insure aeroelastic stability, damping ratio analyses of the hingeless rotor system with CLDT were accomplished at hovering condition due to collective pitch angle changes. Satisfactory results of increasing structural damping and stability were obtained.