• Korean Journal of Artificial Intelligence
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• v.12 no.2
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• pp.17-23
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• 2024

Various methods have been developed to predict the flight path of an air-launched weapon to intercept a fast-moving target in the air. However, it is also getting more challenging to predict the optimal firing zone and provide it to a pilot in real-time during engagements for advanced weapons having new complicated guidance and thrust control. In this study, a method is proposed to develop an optimized weapon engagement zone by the SCG (Scaled Conjugate Gradient) algorithm to achieve both accurate and fast estimates and provide an optimized launch display to a pilot during combat engagement. SCG algorithm is fully automated, includes no critical user-dependent parameters, and avoids an exhaustive search used repeatedly to determine the appropriate stage and size of machine learning. Compared with real data, this study showed that the development of a machine learning-based weapon aiming algorithm can provide proper output for optimum weapon launch zones that can be used for operational fighters. This study also established a process to develop one of the critical aircraft-weapon integration software, which can be commonly used for aircraft integration of air-launched weapons.

• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.63-70
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• 2024

Objective: This study aims to compare the basic aerodynamic characteristics of the official Qatar World Cup soccer ball with those of the official Korean soccer balls. Method: In this study, wind tunnel experiments were conducted to compare the fundamental aerodynamic properties of two commonly used domestic soccer balls, the Star and Nassau, with the Al Rihla, the official ball of the 2022 Qatar World Cup. Results: The findings revealed that the Nassau soccer ball exhibited changes in aerodynamic characteristics depending on its orientation, particularly at low speeds (below 15 m/s), while the Al Rihla showed variations in aerodynamic characteristics at medium to high speeds (15 m/s to 35 m/s) based on its orientation. Furthermore, the results of lift and side force variations indicated that the Star soccer ball exhibited larger changes compared to other soccer balls, suggesting that it may exhibit the most irregular flight path during strong shots (around 30 m/s or approximately 100 km/h). However, there were no differences in aerodynamics observed among the soccer balls in the medium-speed range (20~25 m/s). Conclusion: The comparison of aerodynamics between the Korean soccer balls and the most recently used World Cup official ball showed that, while the Korean balls exhibited slightly greater changes in lift and side forces compared to the World Cup ball, there were no significant differences in most of the aerodynamic characteristics.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1182-1182
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• 2001

In this study, the newly constructed optical measurement system, which was mainly composed of a parametric tunable laser and a near infrared photoelectric multiplier, was introduced to clarify the optical characteristics of wood as discontinuous body with anisotropic cellular structure from the viewpoint of the time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects of the cellular structure of wood sample, the wavelength of the laser beam λ, and the detection position of transmitted light on the time resolved profiles were investigated in detail. The variation of the attenuance of peak maxima At, the time delay of peak maxima Δt and the variation of full width at half maximum Δw were strongly dependent on the feature of cellular structure of a sample and the wavelength of the laser beam. The substantial optical path length became about 30 to 35 times as long as sample thickness except the absorption band of water. Δt ${\times}$ Δw representing the light scattering condition increased exponentially with the sample thickness or the distance between the irradiation point and the end of sample. Around the λ=900-950 nm, there may be considerable light scattering in the lumen of tracheid, which is multiple specular reflection and easy to propagate along the length of wood fiber. Such tendency was remarkable for soft wood with the aggregate of thin layers of cell walls. When we apply TOF-NIRS to the cellular structural materials like wood, it is very important to give attention to the difference in the light scattering within cell wall and the multiple specular-like reflections between cell walls. We tried to express the characteristics of the time resolved profile on the basis of the optical parameters for light propagation determined by the previous studies, which were absorption coefficient K and scattering coefficient S from Kubelka-Munk theory and n from nth power cosine model of radiant intensity. The wavelength dependency of the product of K/S and n, which expressed the light-absorbing and -scattering condition and the degree of anisotropy, respectively, was similar to that of the time delay of peak maxima Δt. The variation of the time resolved profile is governed by the combination of these parameters. So, we can easily find the set of parameters for light propagation synthetically from Δt.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.437-447
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• 2020

The purpose of this study is to research the countermeasures and expected effects through the use of drones in the field of disaster prevention as a drone-based smart quarantine performance method. The environmental, market, and technological approaches to the review of the current quarantine performance task and its countermeasures are as follows. First, in terms of the environment, the effectiveness of the quarantine performance business using drone-based control is to broaden the utilization of forest, bird flu, livestock, facility areas, mosquito larvae, pests, and to simplify and provide various effective prevention systems such as AI and cholera. Second, in terms of market, the standardization of livestock and livestock quarantine laws and regulations according to the use of disinfection and quarantine missions using domestic standardized drones through the introduction of new technologies in the quarantine method, shared growth of related industries and discovery of new markets, and animal disease prevention It brings about the effect of annual budget savings. Third, the technical aspects are (1) on-site application of disinfection and prevention using multi-drone, a new form of animal disease prevention, (2) innovation in the drone industry software field, and (3) diversification of the industry with an integrated drone control / control system applicable to various markets. (4) Big data drone moving path 3D spatial information analysis precise drone traffic information ensures high flight safety, (5) Multiple drones can simultaneously auto-operate and fly, enabling low-cost, high-efficiency system deployment, (6) High precision that this was considered due to the increase in drone users by sector due to the necessity of airplane technology. This study was prepared based on literature surveys and expert opinions, and the future research field needs to prove its effectiveness based on empirical data on drone-based services. The expected effect of this study is to contribute to the active use of drones for disaster prevention work and to establish policies related to them.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5148-5154
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• 2012

The purpose of this study was to analyze the kinematic characteristics of the thrower's center of mass (COM) and the shot that her performance hits record high for the 29th National Athletic Competition. Two S-VHS video cameras were used to visualize. The Direct Linear Transformation technique was employed to paint a clear picture in the three dimensional coordination. Kwon3D was used to analyze the data. The results showed that release velocity and height were 13.73 m/s and 198.6 cm(119% by height ratio), respectively, which is considered as peak performance comparing an extensive review of previous literature on the shot put. Release angle was $34^{\circ}$, which is lower than the previous studies. The path of thrower's center of mass is needed to travel in a release direction during the flight phase. The vertical movement of the thrower's center of mass during the driving should be controlled. At release, the perfact timing is required without vertical and horizontal movements of the thrower's center of mass.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.34-40
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• 2005

Most analyses and researches on Micro Aerial Vehicle(MAV) have focused upon propulsion, automatic control, aerodynamic configuration in low Reynolds number region, and miniaturization of telemetric parts. In the present study, a structural concept for MAV is designed by using the composite material suitable for light flight structures. In order to study the load path and stress state of the MAV, the load and structural analyses are simultaneously performed by the aeroelasticity module of MSC/NASTRAN. The stability derivatives of the MAV are obtained for three symmetric, two antisymmetric, and four unsymmetric maneuvering conditions. Although the aerodynamic theory in MSC/NASTRAN could not be proper for MAV analysis, it provides an traditional and effective tool for trim and load analyses and may be corrected with the results by more accurate theory or test. The results show that the inertial load due to payloads has a more effect on stress rather than the aerodynamic load.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.753-760
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• 2008

The present study is concerned with aerodynamic characteristics and reference trajectory generation of Hope-X in Approach/Landing phase. To create reference trajectory generation in A/L phase, detailed informations on lift and drag coefficients of Hope-X must be provided. To obtain these informations, aerodynamic characteristics of Hope-X are analyzed using the commercial CFD code, Fluent. The A/L phase is conceptually divided into three sub-phases: the Steepglide Slope phase for stability of vehicle, the Flare Maneuver phase for safety landing, the Circular Flare for smooth connecting with these both phases. The reference trajectory is obtained by determination of flight-path angle through geometrical formulas with consideration of aerodynamic coefficient and dynamic characteristic.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.382-392
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• 2020

The use of unmanned aerial vehicle (UAV) have been regarded as a promising technique in both military and civilian applications. Nevertheless, due to the lack of relevant and regulations and laws, the misuse of illegal drones poses a serious threat to social security. In this paper, aiming at deriving the three-dimension optimal surveillance trajectories for group monitoring drones, we develop a group trajectory planner based on the particle swarm optimization and updating mechanism. Together, to evaluate the trajectories generated by proposed trajectory planner, we propose a group-objectives fitness function in accordance with energy consumption, flight risk. The simulation results validate that the group trajectories generated by proposed trajectory planner can preferentially visit important areas while obtaining low energy consumption and minimum flying risk value in various practical situations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.982-992
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• 2017

In this paper, we introduce a method of selection for the optimal transmission polarization of a W-band seeker through the extraction of the one-dimensional scattering center of a ground tank target. We calculated the surface scattering and edge scattering using the shooting and bouncing ray tracing method of the CST A-solver. Based on 4-channel RCS data, using the one-dimensional RELAX algorithm, which is a kind of spectral estimation technique, scattering centers of ground targets were extracted. According to the changes in the polarization state and look angle, we compared and analyzed the scattering center results. Through simulation, we verified that the scattering center results can be applied when feature vectors are used for target recognition.