• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.1
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• pp.49-58
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• 2019

The Scientific balloon is a flight system that could recover an entire platform at the end of the mission. The recovery takes place mainly in low-density populated areas, taking into account for the possible damage to the human life and public safety. In Republic of Korea, on the other hand, marine recovery should be considered due to the dense mountainous terrain and restrictions of the peninsula. In this operating environment, the envelope must be recovered because of severe marine pollution that may occur after the splashdown. Therefore, in this study, the separation device that consists of a location tracker and the waterproof system were developed. The device includes data transmission/reception, separation, and waterproof systems which are manufactured considering the environmental condition of the Korea. The performance of the device and the trajectory of the envelope were verified by conducting a separation test of a 20km platform at a target altitude and the recovery of the zero-pressure balloon.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.9-13
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• 2022

In this paper, the tracking error of monopulse radar caused by cross-eye jamming using terrain bounce is analyzed. Cross-eye jamming is a method of generating an error in a radar tracking system by simultaneously transmitting two signals with different phases and amplitudes. When the monopulse radar receives the cross-eye jamming signal generated by the terrain bounce, a tracking error occurs in the elevation direction. In the presence of multipath, this signal is a combination of the direct target return and a return seemingly emanating from the target image beneath the terrain surface. Terrain bounce jamming has the advantage of using a single jammer, but the space affecting the jamming is limited by the terrain reflection angle and the degree of scattering of the terrain. This study can be usefully used to protect ships from low-altitude missiles or aircraft in the sea.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.489-496
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• 2022

This paper introduces the system for KAU-SPUAV, which is designed and developed by Korea Aerospace University, and verifies its performance through flight test. Specification of two versions of KAU-SPUAV, avionics system, and Ground Control System (GCS) are introduced. Three missions are performed with suggested UAVs: LTE signal mapping, circumnavigation of Jeju island seashore, and long endurance flight. Each mission consists of long distance and long endurance flight which takes advantage of KAU-SPUAV. Research team of KAU-SPUAV confirmed its versatility through suggested flight data. Also based on flight results, the team found the potential of performance improvement of KAU-SPUAV.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.49-56
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• 2022

S-STEP is a small SAR satellite mission that monitors time-limited emergency targets and military anomalies in areas of interest, achieving the average revisit in less than 30 minutes by deploying a constellation of 32 satellites in low orbit at an altitude of 510 km. The mission operation mode of S-STEP is divided into normal mode, observation mode, communication mode, and orbit maintenance mode. Further,, the attitude control mode is subdivides into initial detumbling, sun pointing, target pointing, ground station pointing, and thrust direction maintenance. Based on the preliminary mission operational scenario and the satellite's characteristics, this study analyzed the attitude control performance during initial detumbling and observation modes. It verifies that each mode's attitude control accuracy requirements within the time allotted by the scenario of the S-STEP achieved.

• Journal of the Korea Safety Management & Science
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• v.24 no.4
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• pp.49-59
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• 2022

Mt. Umyeon is a low-altitude mountain near a residential area, and the actual forest area is not large due to the fact that development for use as a living green space is being completed and in progress across the mountain, so the buffering action for landslides was weak. The unit was located at the top of Mt. Umyeon, and there were reports of contents related to the military unit in some accident areas. Some experts suggested that the landslide that started on the cut side of the unit could be one of the causes of the landslide at Mt. Umyeon. It is presumed that there was a sudden collapse of trees that had fallen due to erosion inside the valley. In the case of the Umyeon landslide, localized torrential rain is the biggest cause, but the fact that it suffered a lot of damage is the result of no preemptive measures. In particular, it can be said that the damage was caused by the concentration of residential and commercial facilities due to the unplanned urban expansion without prior review of the feng shui geography of settlement areas. The important lesson we have learned is that we should recognize nature as living things and live in harmony and coexistence between humans and nature through understanding and cooperation. Adapting to changes in the environment can survive, but if it doesn't, it will be slaughtered. As such, geography influences changes in feng shui. Changes in feng shui have a profound effect on not only humans but also the natural ecosystem.

• Journal of Space Technology and Applications
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• v.2 no.2
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• pp.121-136
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• 2022

Automatic Identification System used in ship communication is required for marine control way, including monitoring of vessel operation in coastal and exchanging of information for safety navigation between them. But, it uses a very high frequency band of approximately 160 MHz, and at the same time, due to the curvature of Earth, there is a limit to the communication distance. Several demonstrations were made successfully over satellite, but not much work has been done yet through cube-satellite which has low-orbit at 500 km altitude. Here, we demonstrate a reception test of AIS (automatic identification system) receiver for a cube-satellites using software-defined radio (SDR). We collected AIS data from ship at port of Busan, Korea, using R8202T2 SDR and established to transmit them using Adam-Pluto and Matlab Simulink. The process of weakening the signal strength to a satellite was constructed using attenuator. Through above process, we demonstrated whether AIS data was successfully received from the AIS payload.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.293-299
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• 2023

UPRT(Upset Prevention And Recovery Training) is an accident prevention training program developed over a three-year period after the main cause of aircraft accidents in commercial aviation between 2001 and 2011 was analyzed as LOC-I(Loss Of Control Flight). In 2014, ICAO presented UPRT for fixed-wing aircraft through Doc.10011(Manual On Aeroplane Upset Prevention And Recovery Training) and recommended mandatory implementation to Contracting States from March 2019. Since naval P-3C is a major mission of maritime patrol and anti-submarine warfare, it takes a lot of time to fly at low altitude (70-600 m), and the majority of P-3C pilots have experienced spatial disorientation, so Upset prevention and recovery training is essential for naval P-3C pilots. To this end, this study intends to present measures for UPRT from limited conditions using the P-3C simulator owned by the Navy.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.287-292
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• 2023

The U.S. National Aeronautics and Space Administration proposed a new concept of urban air mobility in the city's short-range air transport ecosystem in order to build a new low-altitude air, and the term uam is currently used worldwide. This paradigm is also being promoted by the Korean government with the goal of commercializing urban air transport services by 2025, and furthermore, the need to secure air maneuvers and transportation capacity is emerging due to the rapidly changing future operating environment and battlefield space. In other words, this study started to present the military necessity and military operation plan by introducing the 'Agility Prime' program of the US Air Force. 'Agility Prime' program was organized in order of background and concept of urban air mobility, development trend of Korean urban air mobility and analysis of the US Air Force's 'Agility Prime' program, and it is expected that this study will be followed by a follow-up study.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.171-171
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• 2022

Effect of temperature during the period of 10 days from transplanting (10 DFT) on the growth and development of rice plants was investigated by transplanting semi-adult seedlings six times from 5 April to 15 May at 10-day interval in the field conditions of 2020 and 2021, with aims to investigate the critical temperature for early transplanting of temperate rice. In the two experimental years, mean temperature for 10 DFT appeared 9.1, 10.5, 11.6, 13.8, 13.9, 16.2, 16.4, 16.7, 17.1, 17.8℃ depending on the transplanting date. Mean temperature of 9.1℃ and 10.5℃ for 10 DFT appeared in the April 5 and April 15 transplants in 2020 showed negative or no effect on the increase of rice growth and acceleration of heading date when compared to those of right after transplanting treatments in the same year. Mean temperature of 11.6℃ for 10 DFT appeared in the April 5 transplant in 2021 demonstrated greater biomass from early to heading stage but the same heading date compared to April 15 transplant, indicating that 11.6℃ for 10 DFT had a positive effect on rice growth but no effect on advanced heading. Both more biomass and advanced heading stage were observed when the mean temperature for 10 DFT was 13.8℃ or higher, compared to those of right after transplanting treatments. These findings indicate that effective 10-DFT mean temperature for rice growth exists between 10.5 and 11.6℃, and that for rice development in terms of heading stage lies between 11.6 and 13.8℃ in natural condition. Further field and indoor studies are suggested to narrow down the critical temperature for early transplanting of temperate rice, which will enable to maximize the crop period in high altitude regions with low temperature.

• Atmosphere
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• v.33 no.5
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• pp.441-456
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• 2023

The mobile observation method, in which a meteorological drone observes while ascending, can observe the vertical profile of wind at 1 m-interval. In addition, since continuous flights are possible at time intervals of less than 30 minutes, high-resolution observation data can be obtained both spatially and temporally. In this study, we verify the accuracy of mobile observation data from meteorological drone (drone) and fill the spatio-temporal observation gaps in the lower atmosphere. To verify the accuracy of mobile observation data observed by drone, it was compared with rawinsonde observation data. The correlation coefficients between two equipment for a wind speed and direction were 0.89 and 0.91, and the root mean square errors were 0.7 m s^-1 and 20.93°. Therefore, it was judged that the drone was suitable for observing vertical profile of the wind using mobile observation method. In addition, we attempted to resolve the observation gaps in the lower atmosphere. First, the vertical observation gaps of the wind profiler between the ground and the 150 m altitude could be resolved by wind observation data using the drone. Secondly, the temporal observation gaps between 3-hour interval in the rawinsonde was resolved through a drone observation case conducted in Taean-gun, Chungcheongnam-do on October 13, 2022. In this case, the drone mobile observation data every 30-minute intervals could observe the low-level jet more detail than the rawinsonde observation data. These results show that the mobile observation data of the drone can be used to fill the spatio-temporal observation gaps in the lower atmosphere.