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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Aviation and Aeronautics
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Journal DOI :
The Korean Society for Aviation and Aeronautics
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Volume & Issues
Volume 15, Issue 4 - Dec 2007
Volume 15, Issue 3 - Sep 2007
Volume 15, Issue 2 - Jun 2007
Volume 15, Issue 1 - Mar 2007
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Effective Thermal Conductivities of Al203 Nanoparticles Suspended in Water with Low Concentration less than 1 Vol. %
Hwang, Kyo-Sik ; Lee, Byeong-Ho ; Kim, Jun-Ho ; Jang, Seok-Pil ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 1~5
In this paper, effective thermal conductivities of water-based Al203-nanofluids with low concentration from 0.01 vol. % to 0.3 vol. % are experimentally obtained by transient hot wire method (THWM). The water-based Al203-nanofluids are manufactured by two-step method which is widely used. To examine suspension and dispersion characteristics of the water-based A1203-nanofluids, Zeta potential as well as transmission electron micrograph (TEM) is observed. We confirm the manufactured Al203-nanofluids have good suspension and dispersion. The effective thermal conductivities of the water-based Al203-nanofluids with low concentration are enhanced up to 1.64% compared with that of DI water at
. In addition, experimental results are compared with theoretical results from Jang and Choi model.
Viscoelastic Damping Treatment Analysis and Aeroelasticity for Vibration Reductions of a Hingeless Composite Helicopter Rotor System
Hwang, Ho-Yon ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 6~14
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.
A Study on Load Spectrum for Fatigue Analysis of Helicopter Rotor Blades
Oh, Man-Seok ; Kim, Hyun-Duk ; Kee, Young-Jung ; Park, Jung-Sun ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 15~23
In this paper, we deducted the missions with respect to Korea utility helicopter (KUH) and consist of the scenarios which describe proper purpose of KUH. And so developed fatigue load spectrum of KUH by applying Helix that is fatigue load spectrum for blade of articulated helicopter rotor system. The developed load spectrum is applied to fatigue analysis of blade by modeled finite element with stress-life method (S-N). And we compared the result of fatigue analysis to prior to Helix for the sake of verifying the load spectrum that we generated.
Vibration Control of Actuators Using Magnetostrictive Materials and PPF Algorithm
Kim, Min-Oug ; Hwang, Ho-Yon ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 24~32
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.
Collision Avoidance Maneuver Simulation of Tilt Rotor Unmanned Aerial Vehicle
Hwang, Soo-Jung ; Lee, Myeong-Kyu ; Oh, Soo-Hun ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 33~45
The collision avoidance maneuver flight simulation for tilt rotor unmanned aerial vehicle was performed by time-accurate numerical integration method based on wind tunnel test data. Five representative collision avoidance maneuvers were simulated under constraints of aerodynamic stall, propulsion power, structural load, and control actuator capability. The collision avoidance performances of the maneuvers were compared by the computed collision avoidance times. The sensitivities of initial flight speed and collision zone shape on the collision avoidance time were investigated. From these results, it was found that the moderate pull-up turn maneuver defined using moderate pitch and maximum roll controls within simulation constraints is the most robust and efficient collision avoidance maneuver under the various flight speeds and collision object shapes in the tilt rotor UAV applications.
Commercial Airline Pilots' Risk Perception of Emergency Flight Situations
Sohn, Young-Woo ; Kim, Yong-Seok ; Kim, Chan ; Park, Su-Ae ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 46~56
This research examined how pilots perceive risks when faced with emergency flight situations. We had 116 commercial airline pilots evaluate riskiness of 39 non-routine flight situations. The pilots' risk perception was analyzed as a function of their position (captain vs. first officer), expertise (expert vs. novice), and military flight experience (with vs. without military experience). Results showed that captains evaluated potential-risk situations and low-risk situations more dangerous than first officers. However, there were no differences between experts and novices, and between pilots having military flight experience and pilots not having military flight experience in risk perception. The analysis of multi-dimensional scaling revealed that the pilots used controllability as a key dimension for evaluating riskiness, though the other dimensions they used varied with their position, expertise, and military flight experience.
Cloud Forecast using Numerical Weather Prediction
Kim, Young-Chul ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 57~62
In this paper, we attempted to produce the cloud forecast that use the numerical weather prediction(NWP) MM5 for objective cloud forecast. We presented two methods for cloud forecast. One of them used total cloud mixing ratio registered to sum(synthesis) of cloud-water and cloud-ice grain mixing ratio those are variables related to cloud among NWP result data and the other method that used relative humidity. An experiment was carried out period from 23th to 24th July 2004. According to the sequence of comparing the derived cloud forecast data with the observed value, it was indicated that both of those have a practical use possibility as cloud forecast method. Specially in this Case study, cloud forecast method that use total cloud mixing ratio indicated good forecast availability to forecast of the low level clouds as well as middle and high level clouds.
A Study on Corroboration of Cultural Factors and Organizational Dissension Management
Kwon, Bo-Hun ; Kim, Chil-Young ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 63~69
Culture is that the system of shared beliefs, values, customs, behaviors, and artifacts that the members of society use to cope with their world and with one another, and that are transmitted from generation to generation through learning. Members of an organization are affected by culture. And dissensions in an organization give negative effects to behavior of the members, especially to satisfaction from organization. This study is on the dissension management by considering of cultural characteristics of pilots. Cultural characteristics of pilots were surveyed and analyzed with the V5M94(values survey module94) which was developed by Hofstede. As results, the cultural indexes of the pilots were different from the national means. The indexes presented that korean pilots' cultural characteristics are low POI, high IDV, low MAS and low UAI as North European cultural characteristics. For managing the pilots group, make expansion of opportunity to take part in decision making, release or share of informations are required. And motivations, delegation, free from unnecessary interventions, understanding and forgiveness rather than disciplinary punishment, thoughtful considerations could be effectiveness. And for developing more effective management methods, management strategies of north european airlines should be studied.
Application of Aircraft Reduced Takeoff Thrust Method
Noh, Kun-Soo ;
Journal of the Korean Society for Aviation and Aeronautics, volume 15, issue 3, 2007, Pages 70~76
The benefits for using reduced takeoff thrust are many, ranging from lower maintenance and operating costs to improved engine and dispatch reliabilities. Some pilots, however, are apprehensive about using reduced thrust. They are particularly reluctant to use the maximum permissible level of reduced thrust. Two common arguments are (1)If reduced thrust is used, then the airplane will not be able to clear the obstacles if an engine fails during takeoff, and (2)If the maximum allowable assumed temperature is used, then there will be no stopping margin left if the takeoff is aborted. There is the notion that using reduced thrust sacrifices safety. The intent of this discussion is to: (1)Show that reduced thrust performance meets all regulatory requirements (2)Show that the Assumed Temperature method includes inherent extra performance margins (3)Show how to maximize performance margins while maximizing thrust reduction