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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 42, Issue 12 - Dec 2014
Volume 42, Issue 11 - Nov 2014
Volume 42, Issue 10 - Oct 2014
Volume 42, Issue 9 - Sep 2014
Volume 42, Issue 8 - Aug 2014
Volume 42, Issue 7 - Jul 2014
Volume 42, Issue 6 - Jun 2014
Volume 42, Issue 5 - May 2014
Volume 42, Issue 4 - Apr 2014
Volume 42, Issue 3 - Mar 2014
Volume 42, Issue 2 - Feb 2014
Volume 42, Issue 1 - Jan 2014
Selecting the target year
Scheduling and Load Balancing Methods of Multithread Parallel Linear Solver of Finite Element Structural Analysis
Kim, Min Ki ; Kim, Seung Jo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 361~367
DOI : 10.5139/JKSAS.2014.42.5.361
In this paper, task scheduling and load balancing methods of multifrontal solution methods of finite element structural analysis in a modern multicore machine are introduced. Many structural analysis problems have generally irregular grid and many kinds of properties and materials. These irregularities and heterogeneities lead to bottleneck of parallelization and cause idle time to analysis. Therefore, task scheduling and load balancing are desired to reduce inefficiency. Several kinds of multithreaded parallelization methods are presented and comparison between static and dynamic task scheduling are shown. To reduce the idle time caused by irregular partitioned subdomains, computational load balancing methods, Balancing all tasks and minmax task pairing balancing, are invented. Theoretical and actual elapsed time are shown and the reason of their performance gap are discussed.
Analysis of Sigma Inflation Factor with Respect to Elevation Angle for GBAS Availability Improvement
Park, Jong-Geun ; Ahn, Jongsun ; Jun, Hyang-Sig ; Yeom, Chan-Hong ; Sung, Sangkyung ; Lee, Young Jae ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 368~375
DOI : 10.5139/JKSAS.2014.42.5.368
The Ground Based Augmentation System (GBAS) is influenced by environmental factors, making analysis in the installation region important. This study has proposed the sigma inflation of the B-value considering the satellite elevation angle and analyzed the Vertical Protection Level (VPL) of the H1 hypothesis. After collecting data that meet the environmental conditions of the installation region, sigma expansion coefficients by the unit of satellite elevation angle (
) have been estimated. The obtained results were functionalized through curve-fitting, and sigma inflation customized for the environmental conditions of the test region was proposed. Then, the characteristics were classified and analyzed depending on humidity and solar activities. According to the sigma inflation with respect to elevation angle analysis, changes in the size of sigma inflation factors by the difference of humidity were minor. However, the VPL under the satellite elevation angle-based sigma inflation met integrity. Also, considering the sigma inflation factor with respect to elevation angle, compared to existing methods, high-integrity and improved availability is confirmed by removing unnecessary margins in high elevation angle satellite.
Backward Path Following Under a Strong Headwind for UAV
Byeon, Gwang-Yeol ; Park, Sanghyuk ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 376~382
DOI : 10.5139/JKSAS.2014.42.5.376
This paper presents a method to enable a UAV in autonomous flight along a desired path to follow it backwards when a strong headwind prevents the vehicle from proceeding forward. The main purpose of the reverse path following in this study is to return to a mission quickly when the wind becomes weaker. When the nonlinear path following guidance law is used, there are two reference points available in the path following. One of the two points is selected considering a flight direction for calculating a straight-line distance(L) from the vehicle to the point for the path following. An initial heading angle with respect to the wind direction determines whether the reverse path following is feasible or not at the time of the wind is generated. The result of the proposed method based on kinematic model in this study is verified through simulations implemented in Matlab.
Proper Orthogonal Decomposition Analysis of Flow Characteristics in Hybrid Rocket Engine
Park, Charyeom ; Lee, Changjin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 383~389
DOI : 10.5139/JKSAS.2014.42.5.383
POD analysis has been done to investigate the internal flow characteristics using LES calculation results of hybrid rocket combustion chamber. The special emphasis was put on the change in the mode energy distribution caused by the installation of diaphragm compared to the baseline case. Also the comparison was made to investigate the effect of wall blowing on the changes in the mode energy between the regions near and far from the diaphragm. For baseline case, POD results clearly distinguish the primary mode containing most of flow energy from the rest of flow modes (2-9 mode) depicting small scale modes. Also, the increase in the energy of flow modes 2-5 is responsible for the formation of relatively large scale structures due to diaphragm. In addition, the comparison of mode energy distributions of flow fields with diaphragm shows similar patterns in both wall blowing and no blowing case. This implies that the local increase in regression rate just after the diaphragm is directly associated with the increase in energy distributions of 2-5 modes.
Hingeless Blade Flexure Bending Stiffness Reinforcement for Whirl Tower Test
Kim, Taejoo ; Kee, Youngjoong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 390~397
DOI : 10.5139/JKSAS.2014.42.5.390
BO-105 helicopter applies hingeless rotor hub system and blade root uses a flexure of hingeless rotor hub system. So bending stiffness reinforcement for flexure was conducted for preparation of whirl tower test using BO-105 blade. Bending moment of flexure area was calculated with FE modeling of section shape for stiffness reinforcement of flexure and thickness of composite material for reinforcement was chosen. Flexure bending stiffness reinforcement was conducted and bending stiffness measurement test was performed before and after bending stiffness reinforcement. And the test data are compared with analysis results.
Secure methodology of the Autocode integrity for the Helicopter Fly-By-Wire Control Law using formal verification tool
An, Seong-Jun ; Cho, In-Je ; Kang, Hye-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 398~405
DOI : 10.5139/JKSAS.2014.42.5.398
Recently the embedded software has been widely applied to the safety-critical systems in aviation and defense industries, therefore, the higher level of reliability, availability and fault tolerance has become a key factor for its implementation into the systems. The integrity of the software can be verified using the static analysis tools. And recent developed static analysis tool can evaluate code integrity through the mathematical analysis method. In this paper we detect the autocode error and violation of coding rules using the formal verification tool, Polyspace(R). And the fundamental errors on the flight control law model have been detected and corrected using the formal verification results. As a result of verification process, FBW helicopter control law autocode can ensure code integrity.
A Study on Reliability Improvement of RALT for KUH through Fault Analysis
Jun, Byung Kyu ; Kim, Young Mok ; Chang, Joong Jin ; Kim, Chang Young ; Hwang, Gil Won ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 406~414
DOI : 10.5139/JKSAS.2014.42.5.406
In this paper, it is introduced characteristics of FMCW-type Radar Altimeter for KUH, and its defects occurred during ground/flight test in initial product phase. In addition, it is also described 'data/control flow model' based fault analysis results of S/W and processes of verifying improvement design through flight test as well as aircraft system integration test called MEP SIL. As a result of design improvement and verification, it is validated that settling the defects and improving not only safety but also capability of the KUH.
Analysis of Revised Helicopter Crashworthiness Criteria
Hwang, Jungsun ; Lee, Sangmok ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 415~422
DOI : 10.5139/JKSAS.2014.42.5.415
There has been a lot of discussion to revise military helicopter crashworthiness design criteria. In this paper, newly revised crashworthiness criteria is analyzed centering around the Crashworthiness Index which is the core content of revised criteria. The Crashworthiness Index(CI) was conceived as an adequate method to quantify the crashworthiness capabilities of a rotorcraft design. The index can rate how well a new or derivative design complies with design requirements. The CI rating is made up of seven assessment areas. While the Basic Airframe Crashworthiness(BAC) area tends to be an objective calculation, other areas of the CI tend to be more subjective. Therefore, in this paper, detail CI calculation process for the BAC area is analyzed to inspect the effectiveness of revised criteria.
Numerical Investigation of On-orbit Thermal Characteristics for Cube Satellite with Passive Attitude Stabilization Method
Oh, Hyun-Ung ; Park, Tae-Yong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 423~429
DOI : 10.5139/JKSAS.2014.42.5.423
Passive attitude stabilization methods using the permanent magnet combined with hysteresis damper and the gravity gradient boom have been widely used for the attitude determination and control of cube satellite, due to its advantage of system simplicity. In this paper, on-orbit thermal characteristics of the cube satellite considering the attitude profiles obtained from the above passive attitude stabilization methods have been investigated through on-orbit thermal analysis. In addition, the effectiveness of the various thermal coatings on the panel for the communication antenna installation has been verified.
Preliminary System Design of STEP Cube Lab. for Verification of Fundamental Space Technology
Kwon, Sung-Cheol ; Jung, Hyun-Mo ; Ha, Heon-Woo ; Han, Sung-Hyun ; Lee, Myung-Jae ; Jeon, Su-Hyeon ; Park, Tae-Young ; Kang, Su-Jin ; Chae, Bong-Gun ; Jang, Su-Eun ; Oh, Hyun-Ung ; Han, Sang-Hyuk ; Choi, Gi-Hyuk ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 430~436
DOI : 10.5139/JKSAS.2014.42.5.430
The mission objective of STEP Cube Lab. (Cube Laboratory for Space Technology Experimental Project) classified as a pico-class satellite is to verify the technical effectiveness of payloads such as variable emittance radiator, SMA washer, oscillating heat pipe and MEMS based solid propellant thruster researched at domestic universities. In addition, the MEMS concentrating photovoltaic power system and the non-explosive holding and separation mechanism with the advantages of high constraint force and low shock level will be developed as the primary payloads for on-orbit verification. In this study, the feasibility of the mission actualization has been confirmed by the preliminary system design.
A Methodology for Estimating Reliability and Development Cost of a New Liquid Rocket Engine -focused on Staged Combustion Cycle with LOX/LH2
Kim, Kyungmee O. ; Hwang, Junwoo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 42, issue 5, 2014, Pages 437~443
DOI : 10.5139/JKSAS.2014.42.5.437
Engine is one of the most important parts in a rocket for completing its mission successfully. In this paper, we provide a methodology for estimating reliability and development cost of a liquid rocket engine newly developed. To estimate reliability, a baseline engine is selected considering factors whose effects on reliability are unquantifiable. Then reliability of a baseline engine is adjusted to reflect the effect of factors that can be modeled quantitatively. Using the previous Transcost engine cost expressed in terms of mass and the number of hot firing tests, the engine development cost is reexpressed in reliability and thrust requirements. Finally, a numerical example is given to illustrate the application of the methodology to a turbopump rocket engine using staged combustion cycle with LOX/LH2 propellant.