김효중 Hyo-joung Kim , 김양원 Yang-won Kim , 권병기 Byung-gi Kwon

DOI: JANT Vol.26(No.2) 47-53, 2022

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With the recent development of defense technology, various aircraft armaments/equipments are being developed. Among them, cruise guided weapons (missile) for launching aircraft can be installed on aircraft after securing reliability and safety through various tests. In order to avoid collision with aircraft, missile separated from aircraft must release restraint of wing at the specified time, control wing in the specified direction. In order to confirm this, a test system that can control MIL-STD-1760 according to safety separation procedure and verify release performance is required. test system needs a function to check circuit for release of restraints and a function to check driving performance by controlling MIL-STD-1760. In addition, test system should be simulate environment separated from aircraft. This paper presented a test system that can verify circuit and driving performance mounted on missile according to the safety separation procedure, and it was confirmed that it was normally separated from aircraft through flight tests.

박유림 Yu-rim Park , 김준환 Jun-hwan Kim , 최현선 Hyun-seon Choi , 정민주 Min-joo Chung

DOI: JANT Vol.26(No.2) 54-62, 2022

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ICAO has recommended data-based aviation safety management and decision-making systems through Annex 19(Safety Management) and Doc 9859(Safety Management Manual), stressing that safety can be greatly improved by sharing aviation safety information throughout the industry. Accordingly, advanced aviation countries have built infrastructure to collect and analyze various aviation safety data in an integrated manner, and also tried to spread identified major safety issues across the industry. On the other hand, in Korea, each stakeholder collects, manages and analyzes safety data individually, so there is a limit to use them in integrative manner. In addition, the scope of using and sharing aviation safety information such as analysis result is also focused on safety management at the national government level, which is insufficient to be shared throughout the industry. Accordingly, the purpose of this study is to present a plan to share and utilize the domestic aviation safety information. To do this, we compare the current situation between FAA and domestic industry and suggest the improvement plans.

김수열 Suyeol Kim , 윤정현 Jeonghyeon Yun , 박병운 Byungwoon Park

DOI: JANT Vol.26(No.2) 63-71, 2022

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Barometers have been used to calculate altitude, and with the development of technology, barometer which had a large volume have now been reduced to about centimeter-level. The altitude calculation using barometer is proceeded using the relationship between reference sea level pressure and the pressure obtained by barometer, and for this, pre-calibration of the barometer is essential. In addition, the barometer has a certain level of bias from actual pressure due to production, and many smartphone manufacturers correct it during the manufacturing process, but it is difficult to correct errors caused by environmental variables. In this paper, we extended methodology of correcting barometer using static reference station to moving drone, and it was possible to calculate the altitude more accurately.

용성중 Sung-jung Yong , 박효경 Hyo-gyeong Park , 유연휘 Yeon-hwi You , 문일영 Il-young Moon

DOI: JANT Vol.26(No.2) 72-77, 2022

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Among the techniques of reinforcement learning, Q-Learning means learning optimal policies by learning Q functions that perform actions in a given state and predict future efficient expectations. Q-Learning is widely used as a basic algorithm for reinforcement learning. In this paper, we studied the effectiveness of selecting and learning efficient paths by designing policies and rewards based on Q-Learning. In addition, the results of the existing algorithm and punishment compensation policy and the proposed punishment reinforcement policy were compared by applying the same number of times of learning to the 8x8 grid environment of the Frozen Lake game. Through this comparison, it was analyzed that the Q-Learning punishment reinforcement policy proposed in this paper can significantly increase the learning speed compared to the application of conventional algorithms.

고요한 Yo-han Ko , 부성춘 Sung-chun Bu , 이철수 Chul-soo Lee , 임재욱 Jae-wook Lim , 채주희 Ju-hui Chae

DOI: JANT Vol.26(No.2) 78-84, 2022

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In this paper, we propose a closed-form based 3D localization method in the presence of multiple signal sources. General localization methods such as TDOA, AOA, and FDOA can estimate a location when a single signal source exists. When there are multiple unknown signal sources, there is a limit in estimating the location. The proposed method calculates a cross-correlation vector of signals received by sensors having an array antenna, and estimates TDOA and AOA values from the cross-correlation values. Then, the coordinate transformation is performed using the position of the reference sensor. Then, the coordinate rotation is performed using the estimated AOA value for the transformed coordinates, and then the three-dimensional position of each emitter is estimated. The proposed method verifies its performance through computer simulation.

곽용길 Yong-kil Kwak

DOI: JANT Vol.26(No.2) 85-90, 2022

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In this study, in order to test the performance of the aircraft system, a threat signal simulator that can transmit a signal similar to the actual threat to the aircraft under test with high power was designed. The high-power threat signal simulator should be able to transmit broadband (UHF band, L band, S band, X band) communication signals and radar signals, and control to transmit signals accurately directed to the aircraft through interfacing tracking radar. The signal strength of the developed equipment is 63 dBm to 93 dBm or more depending on type of signal, and the tracking precision is less than 0.1 degree, which satisfies the required performance. And it was confirmed that the antenna of the high-power threat signal simulator can accurately direct the signal to the aircraft position through the tracking radar interfacing.

장민석 Minseok Jang , 김대호 Daeho Kim , 김희욱 Hee Wook Kim , 정영호 Young-ho Jung

DOI: JANT Vol.26(No.2) 91-98, 2022

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Unmanned aircraft system traffic management (UTM) service for the safe operation of unmanned aerial vehicles (UAV) such as drones using commercial communication networks such as long-term evolution (LTE) and 5G in low-altitude areas of 150m or less is being studied in several countries. In this paper, whether it is possible to secure three-dimensional (3D) coverage for UTM service using the existing LTE cellular network for terrestrial users is analyzed through simulations. The practicality in the real environment is confirmed by performing performance analysis in the actual topographical environment and the LTE base station layouts in Korea. According to the analysis results, as the altitude increases, the number of line-of-sight (LOS) interference base stations increases, resulting in a worse signal to interference plus noise ratio (SINR), but coverage is secured except for the limited areas within 150m. was confirmed to be possible. In addition, it is confirmed that a significant proportion of outage areas could be reduced by placing a small number of additional base stations for the outage area.

김형재 Hyung-jae Kim , 정재원 Jae-won Jung , 이동현 Dong-hyeon Lee , 김길훈 Gil-hoon Kim , 문미연 Mi-youn Moon

DOI: JANT Vol.26(No.2) 99-104, 2022

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Recently, the domestic demand for weapon systems based on aircraft platforms is gradually increasing. In particular, the demand for effective precision guided missile(PGM) which cruises for several hundred kilometers after launch to strike the ground target is rising drastically, but it is in the early stages of development, and research based on it are limited. This paper is a study on the power converter unit(PCU) within PGM which is mounted on an aircraft platform based on MIL-STD-1760, which is an interface between an aircraft and PGM. We investigated the electrical properties and structure of the umbilical connector, and the aircraft/store electrical interconnection system. Also, the focus on the design specifications of the PCU that supplies power were described. This result 3 phase AC input, which is the state for the guided simulation power supply in the state of being mounted on an aircraft that rectification method with power factor correction(PFC) compared to bridge rectifier circuit. In the future, it may be used as a basis for power supply design on aircraft mounted weapon systems.

나승규 Seung-kyu La , 고성협 Sung-hyup Ko , 지대형 Dae-hyeong Ji , 천승재 Seung-jae Chon , 정성훈 Seong-hoon Jeong , 최형식 Hyeung-sik Choi , 김준영 Joon-young Kim

DOI: JANT Vol.26(No.2) 105-112, 2022

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In this paper, unmanned underwater glider was designed for high-depth operation and adopted a bladder-type buoyancy controller for improving battery efficiency, and the motion controller controls the pitch angle by moving the internal mass battery. To improve the energy efficiency of the unmanned underwater glider, a layered PID controller that performs control by section was designed. Simulation program including 6-DOF motion equations and hydrodynamics coefficients of an unmanned underwater glider is constructed using Matlab/Simulink program. Control methods such as PID controller, sliding mode controller and layered PID controller were applied to the simulator to compare the dynamics performance and energy efficiency. As a result, the layered PID controller showed improved control performance compared to other controllers and improved energy efficiency of approximately 7.2% compared to PID controller.

소로 Shohruh Rakhmatov , 고재필 Jaepil Ko

DOI: JANT Vol.26(No.2) 113-118, 2022

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Motivated by people highlighting important phrases while reading or taking notes we propose a neural network training method by highlighting defective pixel areas to classify effectively defect types of images with complex background textures. To verify our proposed method we apply it to the problem of classifying the defect types of tire band fabric images that are too difficult to classify. In addition we propose a backlight highlighting technique which is tailored to the tire band fabric images. Backlight highlighting images can be generated by using both the GradCAM and simple image processing. In our experiment we demonstrated that the proposed highlighting method outperforms the traditional method in the view points of both classification accuracy and training speed. It achieved up to 13.4% accuracy improvement compared to the conventional method. We also showed that the backlight highlighting technique tailored for highlighting tire band fabric images is superior to a contour highlighting technique in terms of accuracy.

김범수 Beomsoo Kim , 김민규 Mingyu Kim , 김정래 Jeongrae Kim , 부성춘 Sungchun Bu , 이철수 Chulsoo Lee

DOI: JANT Vol.26(No.2) 119-124, 2022

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The international gnss service (IGS) provides real-time service (RTS) orbit and clock correction applicable to the broadcast ephemeris of GNSS satellites. However, since the RTS correction cannot be received if the Internet connection is lost, the RTS correction should be predicted and used when a signal interruption occurs in order to perform stable precise point positioning (PPP). In this paper, PPP was performed by predicting orbit and clock correction using a long short-term memory (LSTM) algorithm in real-time during the signal loss. The prediction performance was analyzed by implementing the LSTM algorithm in RPI (raspberry pi), the processing speed of which is not high. Compared to the polynomial prediction model, LSTM showed excellent performance in long-term prediction.