• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.1-10
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• 2023

This study examines the response when the shock by underwater explosion is transmitted to a vertical launch air-vehicle mounted on a ship using modeling and simulation, and is about a plan to increase method shock resistance to protect the air vehicle. In order to obtain an accurate mathematical model, a dynamic characteristic test was performed on similar equipment, and through this, the mathematical model could be supplemented. And, using the supplemented mathematical model, the air vehicle simulated the shock response by the underwater explosion specified in the BV043 standard. As a result of the first simulation, it was confirmed that air vehicle could not withstand shock, and air vehicle protection method using a ring spring type shock absorber was studied. In addition to the basic shape of abosber, it was confirmed that the ring spring absober can be used to increase the impact resistance of a shipborn vertical launch vehicle by performing simulations for each case by changing deseign varables.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.115-123
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• 2018

Various types of robots running on power transmission lines have been developed for the purpose of line patrol monitoring. They usually have complex mechanism to run and avoid obstacles on the power line, but nevertheless did not show satisfactory performance for going over the obstacles. Moreover, they were so heavy that they could not be easily installed on the lines. To compensate these problems, flying robots have been developed and recently, multi-copter drones with flight stability have been used in the electric power industry. The drones could be remotely controlled by human operators to monitor power distribution lines. In the case of transmission line patrol, however, transmission towers are huge and their spans are very long, and thus, it is very difficult for the pilot to control the patrol drones with the naked eye from a long distance away. This means that the risk of a drone crash onto electric power facilities always resides. In addition, there exists another danger of electromagnetic interference with the drones on autopilot waypoint tracking under ultra-high voltage environments. This paper presents a patrol monitoring plan of autopilot drones for power transmission lines and its field tests. First, the magnetic field effect on an autopilot patrol drone is investigated. Then, how to build the flight path to avoid the magnetic interference is proposed and our autopilot drone system is introduced. Finally, the effectiveness of the proposed patrol plan is confirmed through its field test results in the 154 kV, 345 kV and 765 kV transmission lines in Chungcheongnam-do.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.56.1-56.1
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• 2010

MIRIS(Multipurpose InfraRed Imaging System)는 과학기술위성 3호의 주 탑재체로서 2011년 발사예정인 다목적 적외선 카메라 시스템이다. MIRIS는 우주관측 카메라와 지구관측 카메라로 구성되어 있으며, 우주관측 카메라는 $0.9-2.0{\mu}m$ 영역에서 3.67 deg. x 3.67 deg. FOV로 우리 은하평면 survey 관측과 우주배경복사(CIB) 관측을 수행할 것이다. 현재 MIRIS는 비행모델 개발 마무리 단계에 있으며, 검교정 시험, 열-진공 시험, 진동 시험 등을 수행하고 나면 2010년 말 위성 본체와의 조립을 진행할 것이다. 우주관측 카메라는 궤도상에서 태양, 지구의 적외선 복사와 망원경과 검출기 주변에서 발생하는 열잡음을 줄이기 위해 냉각이 필요하며, 제한된 위성의 무게와 부피, 전력등의 요구조건들 때문에 망원경 및 구조체의 복사냉각(Passive Cooling) 방법을 선택하였다. Passive cooling으로 우주관측 카메라의 망원경이 200K 이하로 냉각되면, dewar에 설치된 소형 냉각기를 가동하여 적외선 센서를 80K로 냉각한다. 위성체 내벽과 우주관측카메라의 각 구조체들 사이의 복사를 차단하기위해 30층의 MLI를 적용 하였고, 각 구조체들간의 열전도를 최소화하기위해 GFRP supporter를 적용하였다. 이 실험은 천문(연)에서 자체 제작한 열-진공 챔버를 활용하여 진행하였으며, 이미 인증모델에 대한 passive cooling 실험을 두 차례 실시하였고, 그 실험 결과를 반영하여 최종 비행모델에 대한 실험을 수행하였으며, 그 실험 결과에 대해 논의 하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.503-511
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• 2012

In this paper, the performance analysis of telemetering method using delayed frame time diversity (DFTD) as the outer code and Reed-Solomon (RS) code as the inner code is described. DFTD is used to transmit a real-time frame together with a time-delayed frame which was saved in the memory during a defined period. The RS code as a kind of FEC (forward error correction) is serially concatenated with DFTD. This method was applied to the design of telemetry units that have been used for flight tests in a communication environment with deep fading. The data of the flight test for four cases with no applied code, with DFTD only, with the RS code only, and with both DFTD and the RS code are used to analyze the performance. The simulation for time-delay suggests the possibility that all frame errors can be removed. And the results of 12 flight tests show the performance superiority of this new method to compare with the RS code only.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.611-619
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• 2016

This paper proposes a collision prevention system for an agricultural unmanned helicopter. The collision prevention system consists of an obstacle detection system, a mapping algorithm, and a collision avoidance algorithm. The obstacle detection system based on a LiDAR sensor is implemented in the unmanned helicopter and acquires distance information of obstacles in real-time. Then, an obstacle mapping is carried out by combining the distance to the obstacles with attitude/location data of the unmanned helicopter. In order to prevent a collision, alert is activated to an operator based on the map when the vehicle approaches to the obstacles. Moreover, the developed collision prevention system is verified through flight test simulating a flight pattern aerial spraying.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.439-445
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• 2012

The COMS(Communication, Ocean, and Meteorological Satellite) is subjected to shock loads when the stage or fairing of a launch vehicle is separated and the satellite is separated from the launch vehicle during the launch vehicle flight. And, after the satellite is separated from the launcher, the COMS is subjected to shock loads when the solar array is deployed, Ka-Band communication antenna is deployed, and meteorological imager radiator cover is released. In order to validate the satellite safety against these shock loads on ground, shock tests were performed. In this paper, the shock tests performed in the course of the COMS development are described, and the method to assess the test result is presented with an example of Geostationary Ocean Color Imager(GOCI). In Ariane-5 launch vehicle, the clampband release shock for satellite separation is lower than the fairing or stage separation. In this paper, the extrapolation method to take into account the maximum shock load from the launch vehicle by using the satellite separation shock test result is also introduced.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.862-870
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• 2016

AIS and V-PASS, which are used for safe navigation and automatic vessel arrival and departure, are mandatory standard equipment installed on all ships. If an aircraft is equipped with a ship identification system using AIS and V-PASS, and then ship identification information is received by a vessel such as a large fishery inspection boat or a patrol ship or a ground control system, we can quickly perform maritime surveillance and disaster response. This paper describes the development of a ship identification and display system using a ship identification device for aircraft. Flight test results and a future application plan are also included.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.43-51
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• 2013

This paper describes the development of the telemetry link system for the high data rate transmission in high speed rocket application. In consideration of bandwidth efficiency, frequency selective fading and doppler frequency offset, we used DQPSK instead of PCM/FM which has been the primary modulation format in aeronautical telemetry. Also we used the spatial diversity with multiple receiving antennas to mitigate multipath interference which is the dominant channel impairment and the Turbo Product Code for Forward Error Correction to improve bit error rate performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.5
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• pp.507-517
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• 2010

The KOREAN AIR - R&D Center has developed a solar array for STSAT-2 Flight Model, SaTReC-KAIST, using a fully localized technology and has verified the performance through a launch vibration test, orbit environment test and electrical performance test. The solar array will be launched at NARO Space Center by KSLV-I which is the first Korean launch vehicle, in May 2010. In this paper, a current-voltage curve that shows the power characteristics of solar arrays was derived by applying elements that affects the power performance of STSAT-2's solar arrays to the solar cell equivalent models. The result was compared to LAPSS test results, and accuracy of the solar cell equivalent model and the power performance simulation has been analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.57-64
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• 2005

Modern versions of supersonic jet fighter aircraft using digital flight-by-wire flight control system receive aircraft flight condition such as altitude, airspeed and AoA(angle of attack) from IMFP(Integrated Multi-Function Probe). IMFP sensors data have triplex structure using three IMFP sensors. An air data reconfiguration mode is applied to a T-50 flight control law to guarantee the aircraft flight stability when 2 or 3 IMFP sensors data are invalided. In this study, linear analysis and HQS(Handling Quality Simulator) pilot simulation are performed to analyze flight stability when the air data reconfiguration mode is applied to the control law. And we propose an example that the air data reconfiguration mode is applied to the control law due to second failure of IMFP during T-50 flight. It is found that the aircraft flight stability is not affected when the T-50 flight control law is changed to the air data reconfiguration mode.