• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.205-210
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• 2004

The pulse detonation engine (PDE) has recently expected as a new aerospace propulsion system. The PDE system has high thermal efficiency because of its constant-volume combustion and its simple tube structure. We measured thrust of single-tube pulse detonation rocket (PDR) by two methods using the PDR-Engineering Model (full scale model) for ground testing. The first involved measuring the displacement of the PDR-EM by laser displacement meter, and the second involved measuring the time-averaged thrust by combining a load cell and a spring-damper system. From these two measurements, we obtained 130.1 N of time-averaged thrust, which corresponds to 321.2 sec of effective specific impulse (ISP). As well, we measured the heat flux in the wall of PDE tubes. The heat flux was approximately 400 ㎾/$m^2$. We constructed the PDR-Flight Mode] (PDR-FM). In the vertical flight test in a laboratory, the PDR-FM was flying and keeping its altitude almost constant during 0.3 sec.

• International Journal of Aeronautical and Space Sciences
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• 제13권1호
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• pp.117-125
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• 2012

This paper presented the design of SRPS, ground function test, and the deployment test on a high speed taxi of KC-100 airplane. KAI has developed a spin recovery system in collaboration with Airborne Systems for KC-100 general aviation airplane. Spin mode analysis, rotary balance and forced oscillation tests were performed to obtain the rotational, dynamic derivatives in the preliminary design phase. Prior to the detailed design process of SRPS, approximations for initial estimation of design parameters- fineness ratio, parachute porosity, parachute canopy filling time, and deployment method- were considered. They were done based on the analytical disciplines such as aerodynamics, structures, and stability & control. SRPS consists of parachute, tractor rocket assembly for deployment, attach release mechanism (ARM) and cockpit control system. Before the installation of SRPS in KC-100 airplane, all the control functions of this system were demonstrated by using SBTB(System Breakout Test Box) in the laboratory. SBTB was used to confirm if it can detect faults, and simulate the firing of pyrotechnic devices that control the deployment and jettison of SRPS. Once confirmed normal operation of SRPS, deployment and jettison of parachute on the high speed taxiing were performed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.1-1
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• 2005

Japan Aerospace Exploration Agency(JAXA) has been conducting research and development of the Scramjet engines and their derivative combined cycle engines as hypersonic propulsion system for space access. Its history will be introduced first, and its recent advances, focusing on the engine performance progress, will follow. Finally, future plans for a flight test of scramjet and ground test of combined cycle engine will be introduced. Two types of test facilities for testing those hypersonic engines. namely, the 'Ramjet Engine Test Facility (RJTF)' and the 'High Enthalpy Shock Tunnel (HIEST)' were designed and fabricated during 1988 through 1996. These facilities can test engines under simulated flight Mach numbers up to 8 for the former, whereas beyond 8 for the latter, respectively. Several types of hydrogen-fueled scramjet engines have been designed, fabricated and tested under flight conditions of Mach 4, 6 and 8 in the RJTF since 1996. Initial test results showed that the thrust was insufficient because of occurrence of flow separation caused by combustion in the engines. These difficulty was later eliminated by boundary-layer bleeding and staged fuel injection. Their results were compared with theory to quantify achieved engine performances. The performances with regards to combustion, net thrust are discussed. We have reached the stage where positive net thrust can be attained for all the test coditions. Results of these engine tests will be discussed. We are also intensively attempting the improvement of thrust performance at high speed condition of Mach 8 to 15 in High Enthalpy Shock Tunnel (HIEST). Critical issues for this purposemay be air/fuel mixing enhancement, and temperature control of combustion gas to avoid thermal dissociation. To overcome these issues we developed the Hypermixier engine which applies stream-wise vortices for mixing enhancement, and the M12-engines which optimizes combustor entrance temperature. Moreover, we are going to conduct the flight experiment of the Hypermixer engine by utilizing flight test infrastructure (HyShot) provided by the University of Queensland in fall of 2005 for comparison with the HIEST result. The plan of the flight experiment is also presented.

• 항공우주기술
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• 제7권1호
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• pp.83-90
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• 2008

차세대 저궤도 위성의 탑재소프트웨어 저장메모리는 부트 코드와 모니터 소프트웨어를 내장한 부트 롬과 비행소프트웨어 이미지를 저장한 듀얼 NVMEM 형태로 개발되고 있다. 부트 롬에 내재된 부트 로더는 프로세서 초기화 이후 GPIO의 입력에 따라 비행소프트웨어 모드 혹은 모니터 모드로 천이하게 된다. 비행소프트웨어 모드에서는 듀얼 NVMEM중 선택된 NVMEM에 대한 CRC를 체크하여 정상적일 경우 NVMEM에 저장되어 있는 탑재소프트웨어를 코드가 수행 될 RAM으로 적재 한 후 VxWorks RTO5를 구동하여 테스크를 생성하여 탑재소프트를 수행하게 된다. 모니터 모드에서는 지상에서 NVMEM reprogramming을 가장 메인으로 수행하며 기본적인 보드 레벨 테스트를 수행할 수 있다. 본 논문에서는 차세대 저궤도 위성의 부트 롬 소프트웨어 설계 및 시뮬레이터 기반의 검증 방법에 대하여 기술한다.

• 항공우주시스템공학회지
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• 제18권3호
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• pp.76-85
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• 2024

최근 전 세계적으로 볼 때 소형 무인기에 의한 테러 및 전쟁 활용도가 높아지고 있어 소형 무인기를 대상으로 하는 대공 사격 훈련의 필요성이 더욱 대두 되고 있는 반면, 실제 우리나라의 대공 표적기 사격 훈련은 소음 등의 민원으로 인해 제한되는 사례가 많다. 본 논문에서 효율적인 대공 사격 훈련과 사격장 소음 민원의 해소를 위한, 전기 동력 기반의 직접 타격 형 고속 저소음 소형 대공 표적기의 개발 및 시험 내용을 설명한다. 사격 훈련 시 요구되는 비행 속도 및 비행시간 만족을 위해 비행체 사이징을 수행하고, 해석 프로그램을 사용하여 공력 성능 해석을 수행하였다. 성능해석을 바탕으로 모터 추진시스템 선정 및 가변피치 프로펠러 시스템 설계를 수행하여 성능 시험을 지상시험장치에서 수행 하였고, 최종적으로 비행 시험을 통해 목표 비행 속도, 비행시간 및 비행 소음도를 확인 하였다.

• ETRI Journal
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• 제17권3호
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• pp.1-16
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• 1995

An advanced real-time satellite simulator (ARTSS) has been developed to support the ground operations activities of the ETRI satellite control system, such as testing of the system facilities, validation of flight control procedures, verification of satellite commands as well as training of the ground operators. The design of ARTSS is based on the top-down approach and makes use of a modular programming to ensure flexibility in modification and expansion of the system. Graphics-based monitoring and control facilities enhance the satellite simulation environment. The software spacecraft model in ARTSS simulates the characteristics of a geostationary communication satellite using a momentum bias three-axis stabilization control technique. The system can be also interfaced with a hardware payload subsystem such as Ku-band communication transponder to enhance the simulator capability. Therefore, ARTSS is a high fidelity satellite simulation tool that can be used on low-cost desk top computers. In this paper, we describe the design features, the simulation models and the real-time operating functions of the simulator.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.205-223
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• 2018

During launch a spacecraft is subjected to a variety of dynamical loads transmitted through the launcher to spacecraft interface or air-born transmission excitations in the acoustic pressure field inside the fairing. As a result, spacecraft are tested on ground to ensure and demonstrate the global integrity of the structure against these loads, to screen the flight hardware for quality of workmanship and to validate mathematical models. This paper addresses the numerical modelling and simulation of the low frequency sine and random vibration tests performed on electrodynamic shaker facilities to comprise the mechanical-borne transmission loads through the launcher to spacecraft interface. Consequently, the paper reviews techniques and methodologies to derive a reliable and representative coupled virtual vibration testing simulation environment based on experimental data. These technologies are explored with the main objectives to ensure a stable, reliable and accurate control while testing. As a result, the use of the derived simulation models in combination with the added value of improved control and signal processing algorithms can lead to a safer and smoother vibration test control of the entire environmental test campaign.

• Journal of Positioning, Navigation, and Timing
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• 제9권2호
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• pp.125-129
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• 2020

In this paper, Zero velocity UPdaTe (ZUPT) is implemented on the navigation system of Remotely Piloted Aircraft for GNSS denied environment. RPA's navigation system suffers from lack or loss of satellite signal while maintenance or ground test inside a hangar. Although some of the hangars install GPS repeaters for indoor tests, the anti-jamming equipment with array antenna blocks the repeater signal regarding them as hostile jamming signal. With ZUPT, an aircraft navigation system can be tested free from the divergence of navigation solution without line-of-sight satellites. The designed ZUPT aided centralized Kalman Filter is implemented on the Embedded GPS&INS and simulated with Captive Flight Test data. The simulation result shows stable navigation solution without GNSS updates.

• Journal of Mechanical Science and Technology
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• 제20권1호
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• pp.85-93
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• 2006

The trend of miniaturization has been applied to the research of rockets to develop prototypes of micro rockets. In this paper, the development of a web-integrated prototyping system for three-dimensional micro rockets, and the results of combustion tests are discussed. The body of rocket was made of 6061 aluminum cylinder by lathe process. The three-dimensional micro nozzles were fabricated on the same aluminum by using micro endmills with ${\phi}100{\mu}m{sim}{\phi}500{\mu}m$ diameter. Two types of micro nozzle were fabricated and compared for performance. The total mass of the rockets was 7.32 g and that of propellant (gun powder) was 0.65 g. The thrust-to-weight ratio was between 1.58 and 1.74, and the flight test with 45 degree launch angle from the ground resulted in $46\;m{\sim}53\;m$ of horizontal flight distance. In addition, ABS housing for the micro machined rocket was fabricated using Fused Deposition Modeling (FDM). A web-based design, fabrication, and test system for micro nozzles was proposed to integrate the distributed hardware resources. Test data was sent to the designer via the same web server for the faster feedback to the rocket designer.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.45-45
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• 2017

On-site monitoring of vegetable growth parameters, such as leaf length, leaf area, and fresh weight, in an agricultural field can provide useful information for farmers to establish farm management strategies suitable for optimum production of vegetables. Unmanned Aerial Vehicles (UAVs) are currently gaining a growing interest for agricultural applications. This study reports on validation testing of previously developed vegetable growth estimation models based on UAV-based RGB images for white radish and Chinese cabbage. Specific objective was to investigate the potential of the UAV-based RGB camera system for effectively quantifying temporal and spatial variability in the growth status of white radish and Chinese cabbage in a field. RGB images were acquired based on an automated flight mission with a multi-rotor UAV equipped with a low-cost RGB camera while automatically tracking on a predefined path. The acquired images were initially geo-located based on the log data of flight information saved into the UAV, and then mosaicked using a commerical image processing software. Otsu threshold-based crop coverage and DSM-based crop height were used as two predictor variables of the previously developed multiple linear regression models to estimate growth parameters of vegetables. The predictive capabilities of the UAV sensing system for estimating the growth parameters of the two vegetables were evaluated quantitatively by comparing to ground truth data. There were highly linear relationships between the actual and estimated leaf lengths, widths, and fresh weights, showing coefficients of determination up to 0.7. However, there were differences in slope between the ground truth and estimated values lower than 0.5, thereby requiring the use of a site-specific normalization method.