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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 27, Issue 8 - Dec 1999
Volume 27, Issue 7 - Nov 1999
Volume 27, Issue 5 - Aug 1999
Volume 27, Issue 6 - 00 1999
Volume 27, Issue 4 - 00 1999
Volume 27, Issue 3 - 00 1999
Volume 27, Issue 2 - 00 1999
Volume 27, Issue 1 - 00 1999
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Two-Dimensional Unsteady Flows Around Bodies With Relative Motion Using Unstructured Dynamic Meshes
Park, Young-Min ; Baek, Kyung-Wook ; Kwon, Oh-Joon ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 1~1
A two-dimensional inviscid flow solver is developed for the calculation of unsteady flows around bodies in motion using unstructured meshes. The numerical scheme is based on the cell-centered finite-volume method and the Roe's flux-difference splitting with an explicit Runge-Kutta time integration. Meshes around moving bodies are allowed to follow the motion of the body by introducing the mesh window concept. Intermediate remeshing is also adopted for poor quality meshes due to deformation. Local mesh adaptation is implemented to enhance the solution accuracy of the high gradient flow features. The accuracy of the numerical technique is demonstrated by comparing the results of oscillating airfoils with experimental data. For the unsteady flow analysis with relative motion, wing/store separation with relative translational and rotational motion is investigated.
Airfoil Separation Control for Aerodynamic Performance Enhancement of Rotor-Blade
Park, Young-Whe ; Hong, Seung-Gee ; Lee, Soo-Gab ; Lee, Dong-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 11~11
A new flow control method, which buzzing a portion of an airfoil surface to improve aerodynamic performance of helicopter rotor blade at low Reynolds numbers, is investigated. Through wind tunnel testing, a variety of Reynolds numbers over the range of dynamic stall
, oscillating frequencies and amplitudes we tested to find the effects of these parameters on the aerodynamic performance of the selected airfoil(NACA 0012). The main logic of this idea is to prevent leading-edge laminar separation by direct perturbation of flow field around the airfoil surface. The results show that aerodynamic performance can be greatly improved after stall onset, and give the some possibilities of this concept to enhance the aerodynamic and aero-acoustic performance of the helicopter blade in the future.
Aerodynamic Optimal Design for Wind Turbine Blades and Its Wind Tunnel Tests
Kim, June-Mo ; Oh, Se-Jong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 21~21
During the last decades, some countries already began to search reusable and clean substitutive energies. Wind energy is one of those dream energies, and one important concerns is reducing the production cost. In this study, we develope a method to reduce the production cost by designing the optimal blades for maximum power at given wind speed. This study is based on the modified classical airscrew theory. The designed optimal blades are verified through the wind tunnel tests. In the tests, the pressure distribution is measured at the front and rear sides of the blade disc using the 5-hole spherical probe. The measured pressure difference between the front and rear sides of the disc, and the axial velocity can be a measure of the power absorbed by the turbine from wind. Through the experiments, it is shown that the newly designed turbine blades can absorb more wind energy than those of origin blades at each blade pitch angle.
Aeroelastic Analysis of W-shaped Wing in Subsonic Flow
Koo, Kyo-Nam ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 30~30
A new plane form of wing, W-shaped wing is proposed to enhance aeroelastic stability of swept-forward wing. The W-shaped wing has two sweep angles so that inboard wing is swept back and outboard wing swept forward. Aeroelastic analysis utilizes the finite element method and the doublet point method which are suitable for arbitrary wing. Sweep angle of the inboard wing is changed in this analysis while the outboard wing is fixed to being swept-forward. The results show that the aeroelastic stability can be enhanced drastically by adjusting the sweep angle of inboard wing.
Damage Repair Techniques of Aging Aircraft By Composite
Kim, Wie-Dae ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 37~37
This paper addresses experimental study on the fatigue life of a composite patch repair of the edge cracked aluminium panel of aging aircraft. The experimental study shows that the composite patch repair can improve the static strength by 20% to 30% compared with non-repair case, and the curing cycle which case minimizes a residual thermal stress can increase the static strength and the fatigue life of composite patch specimen. A longer fatigue life can be obtained by using crack tip hole which decreases stress concentration at the crack tip of the specimen. Because the static strength and the fatigue life are strongly dependent on the condition of bonding surfaces between aluminum and patch, it is very important to maintain a proper surface treatment technique in preparation of specimens. The ultrasonic scan method can be used to detect the crack propagation and debonding area of the patch.
Torsional Buckling Analysis of Composite Cylinders
Park, Hoon-Cheol ; Cho, Chahng-Min ; Choi, Youn-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 44~44
Buckling of composite cylinders under torsion has been analyzed using the geometrically nonlinear nine-node assumed strain shell element with six DOF per node. Buckling loads are pinpointed by finding the lowest torsion load that makes the determinant of the global tangent stiffness matrix zero in the course of the geometrically nonlinear analysis. Torsional buckling loads calculated from the present method agree well with the linear buckling loads obtained from various shell theories for most composite cylinders. For cylinders with [30/30/-60]s ply orientation, however, large discrepancy between the two buckling loads has been observed. Comparing the numerical test results with experimental data, we conclude that the present method can estimate the torsional buckling loads of composite cylinders with angle plies. The present paper may provide new reference solutions for torsional buckling loads of composite cylinders
Cure Cycles of Composite Laminates with Viscoelastic Behavior
Jo, You-Sin ; Kang, Jong-Koo ; Lee, Soo-Yong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 53~53
Linear viscoelastic analysis is performed to predict residual stresses occurred in composites during cure. Viscoelastic constitutive equations are defined as functions of temperature and degree of cure. An algorithm of curing process is developed to reduce curing time using constraints imposed on the temperature, the degree of cure and the residual stresses. An optimal cure cycle determined by this curing process algorithm is compared with MRC (manufacturer's recommended we cycle). Since the viscoelastic residual stresses are mostly relaxed at curing stage and hardly relaxed at cool-down stage, there is no big difference between final residual stresses calculated by the optimal cure cycle and the MRC. But the proposed cure cycle in this paper shows a possibility to reduce the curing time considerably as compared to the MRC.
A Control Law for Eigen Axis Rotation in General Moving-to-Rest Maneuver
Oh, Hwa-Suk ; Yoon, Young-Deuk ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 64~64
Eigen axis rotation strategy is useful in Energy minimum and short time maneuver of spacecraft, but its application has been restricted to rest-to-rest maneuvers. When a general moving-to-rest maneuver is required and angular velocity is not parallel to eigen axis initially, then immediate eigen axis maneuver is not available. In this paper, a control law is designed, which moves the angular velocity vector to the direction of eigen axis in short and increases the eigen axis rotation region among whole maneuver time. Designed general eigen axis maneuvering control law is applied to a model spacecraft and simulation results show good responses and improve the fuel consumption.
Design of the satellite range measurement system using a equivalent phase measurement method
Kim, Young-Wan ; Kim, Ho-Kyom ; Oh, Deog-Gil ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 73~73
The equivalent phase measurement method which resolves the range ambiguity in satellite range measurement using tone method was represented in this paper. The range measurement system was implemented with proposed equivalent phase measurement method and PLL circuit for phase lock of tone signal. A range ambiguity may be occurred by the sequential transmission of range tones while a satellite is moving with a velocity and acceleration. A range ambiguity is also occurred in condition of low signal-to-noise ratio of receiving signal with satellite motion because the enough correlation time is necessary to synchronize the phase of a range tone signal. The proposed range measurement method which use two PLL circuit and equivalent phase measurement point shows the good performance with ambiguity resolution in conditions of low signal-to-noise ratio. Also the range measurement method can use in. range of expanded velocity and acceleration of a satellite.
A Study for Handover considering Path Loss, and Doppler Effect in Satellite Mobile Communication Systems
Park, In-Hwan ; Lee, Young-Joon ; Kim, Nak-Myeong ; Cho, Kyeum-Rae ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 81~81
Handover is one of the most important technologies to implement mobile satellite communications in LEO and MEO environments. Handover takes place according to channel environment, signal to noise ratio, and satellite antenna beam coverage. In this paper, the minimum number of handover is calculated considering doppler effects, path losses, and minimum elevation angle which is maintained for the continuous communications to be possible without any severe degradation in quality of service. This paper also suggests the parameters which determine minimum number of handover in satellite communications and analyse the effect of the parameters on handover.
Experiments on the Effects of Coaxial Air on the Nitric Oxides Scaling in Hydrogen Jet Diffusion Flames
Kim, Seung-Han ; Yoon, Young-Bin ; Jeung, In-Seuck ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 90~90
An experimental study has been conducted to investigate the effect of coaxial air on NOx emission scaling in turbulent hydrogen-air jet diffusion flames and compared with the results of simple jet diffusion flame with no coaxial air. In jet diffusion flames with coaxial air, EINOx normalized by flame residence time is found to be correlated with global strain rate (
), showing different scaling characteristics by varying either fuel velocity or coaxial ai. velocity (cases of I, II and III). This may be due to the nonequilibrium effect and the differences of flame radiation loss in each case. It was found that unlike the simple jet diffusion flames EINOx normalized by flame residence time in the coaxial air flame was not correlated with flame residence time only; however, it was scaled with global strain rate successfully. And the effect of radiation heat loss was found to be significant also in hydrogen-air turbulent jet diffusion flames with coaxial air.
A Study on the Atomization Characteristics on Dual Swirl Angle of Dual Airblast Fuel Nozzle
Kang, Shin-Jae ; Rho, Byung-Jun ; Oh, Je-Ha ; Song, Ki-Jung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 99~99
In this study, atomization characteristics of a Dual Airblast Fuel Nozzle are addressed. Three dimensional characteristics of a research Dual Airblast Fuel Nozzle with air swirl are measured to provide the fundamental database. Liquid flow rate is fixed at 0.06kg/min, and the atomizing air is controlled at air-to-liquid mass ratio of 5.0. The performance of the spray with co and counter air swirl flow is measured by the three-component Phase Doppler Particle Analyzer(PDPA) behind the grid in the developed spray region. This instrument was also used to evaluate the concentration profiles. The three dimensional mean velocity, turbulent kinetic energy are investigated to measure the flow characteristics of a Dual Airblast Fuel Nozzle. Drop size distribution, mean droplet size profiles, and concentration are analyzed to understand the atomization characteristics. This experimental result can be conveniently utilized for the preliminary design of gas turbine for aircraft engine where the detail geometry and the performance data are not yet available.
A study on Atomization Characteristics of the Double Impinging F-O-O-F type Injector with Four Streams for Liquid Rocket
Kang, Shin-Jae ; Rho, Byung-Joon ; Oh, Je-Ha ; Park, Sang-Min ; Kwon, Ki-Chul ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 112~112
This paper presents the atomization characteristics of the double impinging F-O-O-F type injector with four streams. The phase/Doppler particle analyzer is employed to measure the droplet-size data and the water is used to inert simulant liquids instead of reactive propellant liquids. Droplet mean diameter(SW) and size distribution are measured to investigate the effect of the momentum ratio and the pressure drop variation. This experimental result can be conveniently used to the preliminary design stage of a impinging stream type injector for liquid rocket.
Ingress/Egress Method of the Fiber Optic Sensor for the Construction of Smart Structures
Gang, Hyeon-Gyu ; Park, Jung-Wan ; Gong, Cheol-Won ; Ryu, Chi-Yeong ; Kim, Dae-Hyeon ; Hong, Chang-Seon ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 121~121
The fiber optic ingress/egress method is one of very important issues for the construction of the smart structure with embedded fiber optic sensors since the optical fiber is fragile to extract and connect with the exterior system. Little attention has been paid to method of practically accessing embedded optical fibers in the literature of sensor activities. In this paper, we proposed the novel out-of-plane ingress/egress method to improve the conventional in-plane ingress/egress method. We developed the protecting method to preserve an exposed optical cable against the curing environments such as high temperature and pressure. We also developed the fiber optic protection component for the optical cable at the exit point. In order to easily connect the smart composite panel to exterior systems, commercial fiber optic FC/APC type jumper cords were used. Furthermore, we developed the fixing component to integrate the composite panel with other connecting parts. The safety and survivability of the optical fiber applied in the ingress/egress method were confirmed by bending tests.
Helicopter Crash Analysis Considering Occupant Survivability & Safety
Chung, Woo-Sik ; Lee, Seon-Woo ; Kim, Seung-Jo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 131~131
Aircraft design philosophy has evolved from meeting the requirements of performance, stability and flightworthiness. In recent decades those of crashworthiness, occupant safety and survivability has been considered and are now being increasingly applied in an overseas production field. The most critical factor for helicopter crash survivability is the vertical impact velocity change requirement since the helicopter spends a large percentage of its operational life in the low-speed, low altitude flight regime. According to a military standard design guide (MIL-STD-1290A), the aircraft should withstand vertical impacts of 12.8 m/sec, within the attitude limits of
degrees roll and -5 degrees to +15 degrees pitch, with a livable volume for the occupants and without causing the occupants to suffer injurious accelerative loads. In this research, we establish numerical FE helicopter model mounted with anthropomorphic Hybrid III Dummy to simulate this helicopter crash in various accident conditions. As the analysis results, we abstract the maximum velocity from the head of dummy and then assess the occupant injury values on the basis of the HIC(Head Injury Criteria) by FMH(Free Motion Headform) analysis.
The KARI Engineering Simulator : A Design Tool for Regional Transport Aircraft Development
Ro, Kap-Seong ; Park, Ju-Won ; Lee, Sang-Hyuk ; Kim, In-Kyu ; Go, Sang-Whee ; Lim, Chul-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 139~139
This paper describes the engineering simulator developed by Korea Aerospace Research Institute (KARI). The main purpose of this simulator is to carry out research and development work in developing a new transport type aircraft. The simulator is composed of low cost, high fidelity subsystems and components capable of complying the top-level requirements by the regulatory body. These components are interconnected via high speed data bus and communication network, while operating with the in-house developed real-time flight simulation software. Throughout the development process, much of the design emphasis is concentrated upon flexibility, expansibility and modularity of the system software and hardware. This paper presents the overall development program of the KARI engineering simulator, including the discussions of study on the use of flight simulator for prototype design, the design requirements and objectives, and the overall features of the simulator. Also discussed are the further development in progress and some of the ongoing research work and future plans.
A Study on the Thermal Analysis of the Basic Trainer Fuel System
Baek, Nak-Gon ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 151~151
This paper describes a study on thermal analysis of a basic trainer fuel system and predicts fuel temperature distribution along a given real mission profile. The analysis was verified by comparing with flight experiments to evaluate the effectiveness of computational program at initial temperature of
. The computer program performs an energy balance equation on thermal network at sub-minute intervals to determine transient temperature for prescribed atmosphere conditions and aircraft flight profiles. The temperature at engine interface showed a good agreement between measured and calculated values within 5% error limits. The vapor-liquid ratio(V/L) which is key parameter for engine performance gets V/L of 0.15 at a fuel temperature of
and this value meets requirement in specification between the aircraft and engine fuel system below 0.3.
Convergence Acceleration Methods For Navier-Stokes Equations
Kwon, Jang-Hyuk ; Sung, Chun-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 159~159
Sung, Bong-Zoo ; Jung, Jin-Dug ; Kwon, Ki-Jung ; Cho, Tae-Whan ; Choi, In-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 27, issue 7, 1999, Pages 167~167