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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Aeronautical & Space Sciences
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Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 37, Issue 12 - Dec 2009
Volume 37, Issue 11 - Nov 2009
Volume 37, Issue 10 - Oct 2009
Volume 37, Issue 9 - Sep 2009
Volume 37, Issue 8 - Aug 2009
Volume 37, Issue 7 - Jul 2009
Volume 37, Issue 6 - Jun 2009
Volume 37, Issue 5 - May 2009
Volume 37, Issue 4 - Apr 2009
Volume 37, Issue 3 - Mar 2009
Volume 37, Issue 2 - Feb 2009
Volume 37, Issue 1 - Jan 2009
Selecting the target year
Unsteady Aerodynamic Analysis for Helicopter Rotor in Hovering and Forward Flight Using Overlapped Grid
Im, Dong-Kyun ; Wie, Seong-Yong ; Kim, Eu-Gene ; Kwon, Jang-Hyuk ; Lee, Duck-Joo ; Park, Soo-Hyung ; Chung, Ki-Hoon ; Kim, Seung-Bum ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 215~223
DOI : 10.5139/JKSAS.2009.37.3.215
In this paper, the helicopter aerodynamics is simulated in hovering and forward flight. Also, an overlapped grid technique is applied in this simulation to consider the blade motion and moving effects. The Caradonna & Tung`s rotor blade was selected to analyze the unsteady aerodynamics in hovering and non-lift forward flight. Also, the AH-1G rotor blade was selected in forward flight. In forward flight case, the numerical trim was applied to determine the cyclic pitching angles using Newton-Raphson method, and the numerical results were in good agreement with experimental data, especially, the BVI effects were well simulated in advancing side in comparison other numerical results. The governing equation is a three dimensional unsteady Euler equation, and the Riemann invariants condition is used for inflow and outflow at the boundary.
Development of an Aerodynamic Performance Analysis Module for Rotorcraft Comprehensive Analysis Code
Lee, Joon-Bae ; Lee, Jae-Won ; Yee, Kwan-Jung ; Oh, Se-Jong ; Kim, Deog-Kwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 224~231
DOI : 10.5139/JKSAS.2009.37.3.224
In this study, an aerodynamic performance analysis code has been developed as a part of rotorcraft comprehensive program. Airloads on rotor blades are calculated based on the blade element theory with look-up tables of aerodynamic coefficients of 2-D airfoils. In order to calculate rotor induced inflow, various inflow prediction methods such as linear inflow, dynamic inflow, prescribed wake and free wake model are integrated into the present module. The aerodynamic characteristics of each method are compared and validated against available experimental data such as Elliot`s inflow distribution and sectional normal force coefficients of AH-1G.
Experimental Study for the Safety Analysis of an External Store Separation from Fighter Aircraft
Yoon, Yong-Hyun ; Cho, Hwan-Kee ; Chung, Hyoung-Seog ; Cho, Dong-Hyun ; Lee, Sang-Hyun ; Baek, Seung-Woock ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 232~239
DOI : 10.5139/JKSAS.2009.37.3.232
The prediction of the separation trajectories of external stores carried by military aircraft is an important task in the area of aircraft design having the objective to define the operational, release envelopes. This paper presents the results obtained for safe store separation from a fighter aircraft by experimental methods in the subsonic wind tunnel. The problems associated with separation of external stores can be studied by the use of several wind-tunnel test techniques. Attention is given the two most useful techniques: 1) dynamically scaled drop-model testing, 2) grid testing. A description of each method is given and data obtained are shown to validate the similarity within acceptable limits.
Wind-Tunnel Investigation for the Aerodynamic Characteristics of Electro-Optical Targeting System
Lee, Sang-Il ; Lee, Jae-Won ; Yee, Kwan-Jung ; Oh, Se-Jong ; Jung, Hyeone-Seok ; Kim, Dae-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 240~247
DOI : 10.5139/JKSAS.2009.37.3.240
Wind tunnel test for Electro-Optical Targeting System(EOTS) has been conducted to investigate the aerodynamic characteristics, especially the torque characteristics of the rotating parts to insure the enough actuator power during the actual operation. The influence of EOTS`s complex configuration, such as the observation window, has been investigated by comparing with the results of the simplified models made of half sphere and the cylinder. It has been found that the position of the observation window of EOTS has an effect on surface pressure distribution and the torque characteristics of the rotating observation part.
An Efficient Global Optimization Method for Reducing the Wave Drag in Transonic Regime
Jung, Sung-Ki ; Myong, Rho-Shin ; Cho, Tae-Hwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 248~254
DOI : 10.5139/JKSAS.2009.37.3.248
The use of evolutionary algorithm is limited in the field of aerodynamics, mainly because the population-based search algorithm requires excessive CPU time. In this paper a coupling method with adaptive range genetic algorithm for floating point and back-propagation neural network is proposed to efficiently obtain a converged solution. As a result, it is shown that a reduction of 14% and 33% respectively in wave drag and its consumed time can be achieved by the new method.
A New Process for the Requirements Based Aerospace System Design and Optimization
Park, Hyeong-Uk ; Lee, Jae-Woo ; Byun, Yung-Hwan ; Chung, Joon ; Behdinan, Karman ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 255~266
DOI : 10.5139/JKSAS.2009.37.3.255
In this study, a robust aerospace system design process for the aerospace system is developed by considering the uncertainties of user requirements, manufacturing errors, and operational environment variation. User requirements are analyzed and quantified by decision making models and system engineering methods to select alternative concepts which satisfies the various requirements. Robust design and optimization method is applied to derive the robust solution of the selected system. First, a variance of objective function is calculated, and a mean value and a variance of target value are determined by the deterministic design optimization results of the system. A robust optimum design formulation is then needed to derive the robust solution that minimizes the variance of the response and moves the mean values to the target value. It is applied to Very Light Jet (VLJ) aircraft to which much attention is paid recently in civil aerospace market.
Vision-based Target Tracking for UAV and Relative Depth Estimation using Optical Flow
Jo, Seon-Yeong ; Kim, Jong-Hun ; Kim, Jung-Ho ; Lee, Dae-Woo ; Cho, Kyeum-Rae ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 267~274
DOI : 10.5139/JKSAS.2009.37.3.267
Recently, UAVs (Unmanned Aerial Vehicles) are expected much as the Unmanned Systems for various missions. These missions are often based on the Vision System. Especially, missions such as surveillance and pursuit have a process which is carried on through the transmitted vision data from the UAV. In case of small UAVs, monocular vision is often used to consider weights and expenses. Research of missions performance using the monocular vision is continued but, actually, ground and target model have difference in distance from the UAV. So, 3D distance measurement is still incorrect. In this study, Mean-Shift Algorithm, Optical Flow and Subspace Method are posed to estimate the relative depth. Mean-Shift Algorithm is used for target tracking and determining Region of Interest (ROI). Optical Flow includes image motion information using pixel intensity. After that, Subspace Method computes the translation and rotation of image and estimates the relative depth. Finally, we present the results of this study using images obtained from the UAV experiments.
Numerical Research on the Lock-in Compensation Method of a Ring Laser Gyroscope for Reducing INS Alignment Time
Shim, Kyu-Min ; Jang, Suk-Won ; Paik, Bok-Soo ; Chung, Tae-Ho ; Moon, Hong-Key ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 275~282
DOI : 10.5139/JKSAS.2009.37.3.275
Generally, the sinusoidal cavity dither is adopted to ring laser gyroscope for eliminating the lock-in which is non-linear effect at the small rotation input. Despite this method, there are some remained errors which are generated at the dither turnaround, and those errors produce random walk which is a general character of a ring laser gyroscope. As one of the numerous research results for compensating these errors, there is a special lock-in compensation method which is the method of error estimation and compensation by comparing the beat signal periods of before and after the dither turnarounds. In this paper, by ring laser gyroscope modeling and numerical analysis, we verified the theoretical validity and confirmed the effectiveness of this method in expectation of the possible beat signal measurement time resolution. As a result, we confirmed the random walk decreases from a-half to a-third by this lock-in compensation method. So, it is expected to be a remarkable method for reducing the INS alignment time.
A Study on Estimation of Energy required for Fin Unfolding
Jung, Suk-Young ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 283~292
DOI : 10.5139/JKSAS.2009.37.3.283
Considering an integral equation governing the motion of unfolding fin, an algebraic equation was acquired to get estimated minimum deployment energy required for the successful fin unfolding under the given wind condition. To complete the integration of moment, some approximations had to be introduced particularly to frictional moment and aerodynamic damping for which deployment angular speed of the unfolding fin was modelled as a function of deployment angle only with assumed profile using expected maximum angular speed. Technique for the estimation of the minimum required deployment energy was finalized by introducing the ideal deployment angular speed representing work done by the fin unfolding device alone during fin unfolding and was confirmed by comparing results from simulation with various aerodynamic conditions and profiles of the hinge torque.
Design and Fabrication of a small Coaxial Rotorcraft UAV
Kim, Sang-Deok ; Byun, Young-Seop ; Song, Jun-Beom ; Lee, Byoung-Eon ; Song, Woo-Jin ; Kim, Jeong ; Kang, Beom-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 293~300
DOI : 10.5139/JKSAS.2009.37.3.293
The rotorcraft-based unmanned aerial vehicle(UAV) capable of performing close-range surveillance and reconnaissance has been developed. Trade studies on mission feasibility led to the adoption of a coaxial rotorcraft with twin rotors counter-rotating in one axis and driven by electric motors. A commercial off-the-shelf flight control computer(FCC) and a radio frequency modem were adopted for autonomous navigation. In order to achieve an aerial view, commercial charge-coupled device camera was also integrated into the vehicle. The performance of the completed vehicle was proved with manual flight test, and mission capability was verified through waypoint navigation flight after being equipped with FCC. This paper treats the whole process of design and system integration for development of the coaxial rotorcraft UAV.
A Rotating Balance Design and Performance Estimation for a Rotor Test Jig
Ryi, Jae-Ha ; Rhee, Wook ; Choi, Jong-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 301~306
DOI : 10.5139/JKSAS.2009.37.3.301
In this study a 3-component rotating balance, which is designed to measure the thrust (Fz) and two moment components (Mx, My) simultaneously for a rotor test jig, is designed and its performance is validated experimentally. The low voltage signal from the strain gages mounted on the balance is amplified with a rotating amplifier, which is then fed through a slip-ring unit into the data acquisition system. In order to validate the accuracy of the calibration matrix obtained from a static calibration test, an additional reaction type balance is used to measure the thrust from a model rotor simultaneously, and shows very good result. Finally, the expanded uncertainty value, which is obtained from ISO method is estimated to be
, and the balance turns out to be reliable.
Pyroshock and Vibration Isolation using SMA Mesh Washer Isolator
Youn, Se-Hyun ; Jang, Young-Soon ; Han, Jae-Hung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 307~313
DOI : 10.5139/JKSAS.2009.37.3.307
In general, pyroshock is generated from the actuation of separation devices for several stage, fairing, and satellite separation in the flight of a launch vehicle. During these events, transient vibration phenomenon called pyroshock, which shows large acceleration in the high frequency range, occurs and it can result in the malfunction of electronic components which is equipped inside the launch vehicle or satellite. In this paper, mesh washer isolators made out of SMA were introduced for the isolation of pyroshock. One type of isolator primarily used pseudoelastic characteristics of SMA and the other type of isolator used shape memory effect of SMA. For the study of basic load-displacement relationship of each SMA isolator, compressive loading tests were performed and the results showed the capability of the isolator itself. Pyroshock isolation tests were followed and verified the outstanding isolation performance of isolator. In addition, random vibration tests were also performed and checked the dynamic characteristics of each SMA isolator.
Weather Characteristics of Oenarodo Space Center
Kim, Jhoon ; Kook, B.J. ; Moon, K.J. ; Lee, J.H. ; Koo, J.H. ; Park, S.S. ; Lee, H.K. ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 3, 2009, Pages 314~327
DOI : 10.5139/JKSAS.2009.37.3.314
Weather launch criteria of launch at Oenarodo Space Center is important for the successful launch operation. In particular, most of the launch failure occurs during the period of separation from the launch pad, thus meteorological condition is critical at this phase. In earlier days, the weather launch criteria adopted wind and forecast data for the launch operation. Nevertheless, the control of position and stability require other meteorological components such as vertical wind shear, lightning, temperature and visibility, because the launch vehicle is moving mostly vertically. We analyze these meteorological components by using the observed data at KMA at neighboring Oenarodo to determine the weather launch criteria. These criteria need further refinements through long-term observation.