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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
Journal Basic Information
Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 39, Issue 12 - Dec 2011
Volume 39, Issue 11 - Nov 2011
Volume 39, Issue 10 - Oct 2011
Volume 39, Issue 9 - Sep 2011
Volume 39, Issue 8 - Aug 2011
Volume 39, Issue 7 - Jul 2011
Volume 39, Issue 6 - Jun 2011
Volume 39, Issue 5 - May 2011
Volume 39, Issue 4 - Apr 2011
Volume 39, Issue 3 - Mar 2011
Volume 39, Issue 2 - Feb 2011
Volume 39, Issue 1 - Jan 2011
Selecting the target year
Numerical Study on Flow Characteristics of Synthetic Jet with Rectangular and Circular Slot Exit
Kim, Min-Hee ; Kim, Woo-Re ; Kim, Chong-Am ; Jung, Kyung-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 585~595
DOI : 10.5139/JKSAS.2011.39.7.585
The flow characteristics of synthetic jet depending on rectangular and circular jet exit configuration are investigated using numerical computation with cross flow. In rectangular slot, synthetic jet generates the strong vortex but supplies fewer momentum and effectiveness of flow control is reduced along flow direction. In circular slot, regular vortex is formed from slot center to end. It affects the wider region than rectangular slot. The distribution of wall shear stress is considered in order to indicate the effectiveness of flow control device for flow separation delay. Consequently, circular slot is a more suitable candidate for delaying flow separation. In order to derive the optimal shape of a circular slot exit, hole gap and diameter that affect the flow structure and flow control were analyzed. As a result, consider the hole diameter and gap of circular slot exit design, effectiveness of the flow control can be increased.
CFD analysis of the Disk Friction Loss on the Centrifugal Compressor Impeller
Kim, Hyun-Yop ; Cho, Lee-Sang ; Cho, Jin-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 596~604
DOI : 10.5139/JKSAS.2011.39.7.596
To improve the total efficiency of centrifugal compressor, it is necessary to reduce the disk friction loss, which is defined as the power loss. In this study, the disk friction loss due to the axial clearance and the surface roughness effect is analyzed and proposed the new empirical equation for the reduction of the disk friction loss. The rotating reference frame technique and the 2-equation k-
SST model using commercial CFD code FLUENT is used for the steady-state analysis of the centrifugal compressor impeller. According to CFD results, the disk friction loss of the impeller is more affected by the surface roughness than the change of the axial clearance. For the minimization of the disk friction loss on the centrifugal compressor impeller, the magnitude of the axial clearance should be designed to the same size compare with theoretical boundary layer thickness and the surface roughness should be minimized.
Non-linear Shimmy Analysis of a Nose Landing Gear with Friction
Yi, Mi-Seon ; Bae, Jae-Sung ; Hwang, Jae-Hyuk ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 605~611
DOI : 10.5139/JKSAS.2011.39.7.605
Shimmy is a self-excited vibration in lateral and torsional directions of a landing gear during either the take-off or landing. It is caused by a couple of conditions such as a low torsional stiffness of the strut, a free-play in the landing gear, a wheel imbalance, or worn parts, and it may make the aircraft unstable. This study was performed for an analysis of the shimmy stability on a small aircraft. A nose landing gear was modeled as a linear system and characterized by state-equations which were used to analyze the stability both in the frequency and time-domain for predicting whether the shimmy occurs and investigating a good design range of the important parameters. The root-locus method and the 4th Runge-Kutta method were used for each analysis. Because the present system has a simple mechanism using a friction to reinforce the stability, the friction, a non-linear factor, was linearized by a describing function and considered in the analysis and observed the result of the instability reduction.
Fatigue Life Prediction and Ratcheting behavior of the Elbrodur-NIB under Fatigue loading with mean stress
Lim, Chang-Bum ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 612~617
DOI : 10.5139/JKSAS.2011.39.7.612
An experimental study was carried out for the Elbrodur-NIB(copper alloy) at room temperature under stress-controlled uniaxial fatigue loading with and without mean stress. As a result, the effects of stress amplitude, mean stress and stress rate on ratcheting behavior were investigated. The ratcheting strain increased with increasing stress amplitude for a given mean stress, and with mean stress for a given stress amplitude. But, the ratcheting strain decreased as the stress rate increased. The three mean stress models were investigated and the mean stress models of Smith-Watson-Topper and Walker yielded good correlation of fatigue lives in the life range of
Tight Path Following PID Controller for a Vehicle with Time Delay
Rhee, Ihn-Seok ; Park, Sang-Hyuk ; Lee, Kyoung-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 618~626
DOI : 10.5139/JKSAS.2011.39.7.618
In order to complete missions in a complicated terrain or highly dangerous area, an unmanned aerial vehicle(UAV) needs a fine controller to precisely follow the desired path. A PID controller used for the path following feeds forward path curvature information to the control input to improve the path following performance. High gain for PID controller is necessary to follow path tightly. However the high gain could cause instability or performance degradation when the vehicle has slow dynamics. We present PID controller design method which considers response delay of vehicle as well as path curvature. In order to obtain path curvature the desired path is described as a 3rd order polynomial by applying cubic spline interpolation. We apply the proposed controller to the path following of a UAV which is operated in high altitude and has very slow lateral dynamics. The lateral dynamics are modelled as a first order delayed system in the controller design. Nonlinear simulation shows the UAV with proposed controller follows an arbitrary path very tightly.
Performance Evaluation of Hydrogen Generator for Fuel Cell Unmanned Aircraft
Park, Dae-Il ; Kim, Sung-Uk ; Kim, Dong-Min ; Kim, Tae-Gyu ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 627~633
DOI : 10.5139/JKSAS.2011.39.7.627
Performance of a hydrogen generator for a fuel cell unmanned aircraft was evaluated as the change of temperature environment. Sodium borohydride (
) was used as a hydrogen source due to its high hydrogen content and good storability. The hydrogen gas was generated by the hydrolysis reaction using a catalytic reactor. Reaction chambers were set up with the range of temperatures from -20 to
. The hydrogen generation rate and temperatures changes of reactor and separator were measured at the
concentrations of 20 and 25wt.%. As a result, the hydrogen generation rate was decreased as the repeated reaction cycles. It showed that the hydrogen generation rate was stable at low temperature, while at high temperature the hydrogen generation rate was rapidly decreased. The performance degradation was mainly caused by the catalyst loss and
deposition on the catalyst surface.
Steady/Unsteady Cavitating Flow Analysis of Pilot Valve in Flight Actuator System Using Dynamic Moving Mesh
Son, Kap-Sik ; Lee, Sea-Wook ; Kim, Dae-Hyun ; Kim, Sang-Beom ; Park, Sang-Joon ; Jang, Ki-Won ; Cho, Jin-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 634~642
DOI : 10.5139/JKSAS.2011.39.7.634
A numerical analysis of steady/unsteady flow applying cavitation model and moving mesh method was carried out in order to analyze flow and response characteristics inside the pilot valve which controls the flight actuator system. The flow of the valve was assessed according to operation temperature and time. This research has found that valve characteristics became stable at above a specific temperature and the cavitation affected valve's performance. Internal pressure and response characteristics of the valve were analyzed and flow characteristics of steady and developed unsteady flow were confirmed to be matched each other.
Effect of joining methods on the failure of aluminum honeycomb sandwich joints under shear loading
Park, Yong-Bin ; Kweon, Jin-Hwe ; Choi, Jin-Ho ; Cho, Hyun-Il ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 643~651
DOI : 10.5139/JKSAS.2011.39.7.643
An experimental study on the failure of aluminum sandwich joints under shear loading was conducted. A total of 60 specimens including three different insert types and two different potting types were fabricated and tested. The test results showed that the through-clearance type of joint fails at the highest load among insert type joints. The failure load of the potted joints with the dimple washer increased by 10% compared to the simple potted joints. As expected, the shear failure load became higher in accordance with the face thickness increase. It was also found that the upper face in contact with the loading tool is more dominant over the failure load.
Computation of Flowfield and Infrared Signature in Aircraft Exhaust System for IR Reduction Design
Moon, Hyuk ; Yang, Young-Rok ; Chun, Soo-Hwan ; Choi, Seong-Man ; Myong, Rho-Shin ; Cho, Tae-Hwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 652~659
DOI : 10.5139/JKSAS.2011.39.7.652
A computational system to predict flowfield and infrared signature in aircraft exhaust system is developed. As the first step, a virtual mission profile is considered and an engine is selected through a performance analysis. Then a nozzle that meets the requirement of each mission is designed. The internal flow in the exhaustion nozzle at the maximum thrust is analyzed using a state-of-the-art CFD code. In addition, a system to combine information of the skin temperature distribution of the nozzle and after-body surface with an infrared prediction code is developed. Finally, qualitative results for the infrared signature reduction design are obtained by investigating the infrared signature level under various conditions.
The Cockpit Development for the Reconfigurable Flight Simulator
Yang, Ji-Youn ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 660~665
DOI : 10.5139/JKSAS.2011.39.7.660
Reconfigurable Flight Simulator for an airborne tactical mission based on virtual reality technology is developed as a software configurable cockpit with computer display as virtual instruments. It can simulate F-15K, KF-16, T/A-50 class fighter and depending on simulated cockpit, control stick and throttle are replaceable. For effective immersion, Video See-Through type HMD is applied.
Development of the MEP Integration Test Environment for Surion
Kim, Yoo-Kyung ; Kim, Myung-Chin ; Choi, Won-Woo ; Oh, Woo-Seop ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 666~673
DOI : 10.5139/JKSAS.2011.39.7.666
To perform effective integration test of avionics equipments, the importance of a setup for integration test environment has been increasing in recently developed aircraft. Especially, the development of integration test equipment is necessary for minimizing the development period and reliability of integration test. This paper treats the model development for optimal working of integration test after analyzing the characteristics of each MEP equipments for Surion(KUH). Models, whose main role is troubleshooting of equipment and simulation for missing equipments, consists of dynamic, behavior, and ICD models depending on the dynamic characteristics. Software test for both unit level and system level are performed to verify the model reliability. By conducting integration test using SIL, it is confirmed that the developed models are suitable for integration function test of the MEP system.
Analysis of the Collision Probability and Mission Environment for GEO
Seong, Jae-Dong ; Lee, Dae-Woo ; Cho, Kyeum-Rae ; Kim, Hae-Dong ; Kim, Hak-Jung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 674~681
DOI : 10.5139/JKSAS.2011.39.7.674
The increasing number of orbital debris objects is a risk for satellite operations due to space activities over past 50 years since launched Sputnik. The GEO (Geostationary Earth Orbit), where COMS-1 is being operated since last June 2010, has more and more risks that collide with space debris or another satellites. In this paper, as a preliminary study about GEO satellite collision probability and operations environment, collision probability between COMS-1 and RADUGA 1-7 that is one of Russian military communication satellites is investigated and analyzed. Indeed, the space environment including space debris of COMS-1 is presented. As a result, it is noted that collision probability between two satellites using NORAD TLEs on 14th Jan. 2011 was 2.8753E-07 in case that position uncertainty was assumed 10km. Particularly, the largest proportion of space debris around COMS-1's mission orbit is meteoroids.
Calibration Mirror Mechanism with Fail-Safe Function
Lee, Kyong-Min ; Oh, Hyun-Ung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 39, issue 7, 2011, Pages 682~687
DOI : 10.5139/JKSAS.2011.39.7.682
Calibration mirror mechanism has been widely used for on-board calibration with black body. The calibration mirror is deployed to reflect the radiation energy from the black body to the image sensor for calibrating the sensor system. After the calibration, the calibration mirror is stowed not to hide a main optical path. It also has a fail-safe function which can stow the mirror by just removing the input power of motor when the calibration mirror is stopped at certain position during the calibration. In the present work, the operation concept, design, torque analysis and functional test results of the calibration mirror mechanism with the aforementioned function have been introduced and investigated.