• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.1
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• pp.1-10
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• 2023

This study investigated the accident cases of the U.S. Air Force and the R.O.K. Army. It analyzed the accident factors of the unmanned aircraft system using case analysis on unmanned aircraft system operators of the R.O.K. Air Force. Following the analysis this paper suggested safety operation plans for the R.O.K. Air Force. The risk factors of unmanned aircraft system were summarized by collecting and analyzing accident cases of unmanned aircraft system by the U.S. Air Force, collecting and analyzing accident risk factors of RQ-4 operators of the R.O.K. Air Force. Through the analyzed risk factors, a safety operation plan for the semi-automatic unmanned aircraft system and the fully automatic unmanned aircraft system was presented.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.80-85
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• 2008

The prediction of the separation trajectories of external stores released from a military aircraft is an important task in the aircraft design area having the objective to define the operational and release envelopes. This paper presents the results obtained for store separation by employing commercial softwares, FLUENT and CFD-FASTRAN. FLUENT treats the rigid body motion by employing a remeshing scheme. CFD-FASTRAN uses Chimera(overset) grid and interpolations. It was found that, for the prediction of the trajectories and behavior of the stores separated from the wing, both codes show the good agreement with the experimental results.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.27 no.1
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• pp.1-9
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• 2019

The purpose of this study was to investigate the relationship among Calling, Role conflict, and Turnover intention of Republic of Korea Air force pilot. Specifically, we examined the mediating effect of Role conflict on the relationship between Calling and Turnover intention. Survey data from 211 Pilots in R.O.K. Air force bases were analyzed with Structural equation model, using AMOS 21.0. Results are as follows. First, Calling had negative relationships with Role conflict and Turnover intention. Second, Role conflict had a positive relationship with Turnover intention. Third, Role conflict partially mediated on the relationship between Calling and Turnover intention. These findings suggest that Calling may play a critical role in Turnover intention and Role conflict of R.O.K. Air force pilot. Finally, we discussed the implications of these results, limitations, and research suggestions for the future research.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.371-381
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• 2016

Objective:This study aims to evaluate the features of heart rate variability (HRV) and respiratory signals as indices for a driver's drowsiness and waking status in order to develop the classification model for a driver's drowsiness and waking status using those features. Background: Driver's drowsiness is one of the major causal factors for traffic accidents. This study hypothesized that the application of combined bio-signals to monitor the alertness level of drivers would improve the effectiveness of the classification techniques of driver's drowsiness. Method: The features of three heart rate variability (HRV) measurements including low frequency (LF), high frequency (HF), and LF/HF ratio and two respiratory measurements including peak and rate were acquired by the monotonous car driving simulation experiments using the photoplethysmogram (PPG) and respiration sensors. The experiments were repeated a total of 50 times on five healthy male participants in their 20s to 50s. The classification model was developed by selecting the optimal measurements, applying a binary logistic regression method and performing 3-fold cross validation. Results: The power of LF, HF, and LF/HF ratio, and the respiration peak of drowsiness status were reduced by 38%, 22%, 31%, and 7%, compared to those of waking status, while respiration rate was increased by 3%. The classification sensitivity of the model using both HRV and respiratory features (91.4%) was improved, compared to that of the model using only HRV feature (89.8%) and that using only respiratory feature (83.6%). Conclusion: This study suggests that the classification of driver's drowsiness and waking status may be improved by utilizing a combination of HRV and respiratory features. Application: The results of this study can be applied to the development of driver's drowsiness prevention systems.

• The Korean Journal of Air & Space Law and Policy
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• v.8
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• pp.217-230
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• 1996

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.345-351
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• 2017

A wind tunnel test for the scaled parachute models was performed to verify aerodynamic characteristics for practical usage of Korean low cost low altitude aerial delivery system. The cruciform shaped cargo parachute models for heavy and light weight were ejected into wind tunnel test section; and the drag forces acting on the models in steady condition were measured in accordance with velocity. Also, the maximum opening forces during inflation were obtained and captured by a high speed camera to analyze the inflation characteristics and evaluate the design of the low cost aerial delivery system. The results showed a reliable stability and met the design requirement of delivery operation system for R.O.K Air Force.

• Proceedings of the Korea Crystallographic Association Conference
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• 2005.11a
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• pp.7-7
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• 2005

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.1
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• pp.47-57
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• 2022

UAVs have been deployed various missions such as deception, reconnaissance and attack since they have been applied in battlefield and achieved missions successfully instead of man. In the past, it is impossible for UAVs to conduct autonomous missions or cooperative mission between manned aircraft due to the limitation of the technology. However, theses missions are possible owing to the advance in communication and AI Technology. In this research, we identified the possible cooperative missions between manned and unmanned team based on air-to-air mission. We studied cooperative manned and unmanned tactics about fighter sweep mission which is the core and basic operation among various air-to-air missions. We also developed cooperative tactics of manned and unmanned team by classifying nonstealth and stealth confrontational tactics. Hereafter, we verified the validity of the suggested tactics using computer simulations.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.13-20
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• 2003

Both MgO and $Sc_2O_3$ are shown to provide low interface state densities (in the $10^{11}{\;}eV^{-1}{\;}cm{\;}^{-2}$ range)on n-and p-GaN, making them useful for gate dielectrics for metal-oxide semiconductor(MOS) devices and also as surface passivation layers to mitigate current collapse in GaN/AlGaN high electron mobility transistors(HEMTs).Clear evidence of inversion has been demonstrated in gate-controlled MOS p-GaN diodes using both types of oxide. Charge pumping measurements on diodes undergoing a high temperature implant activation anneal show a total surface state density of $~3{\;}{\times}{\;}10^{12}{\;}cm^{-2}$. On HEMT structures, both oxides provide effective passivation of surface states and these devices show improved output power. The MgO/GaN structures are also found to be quite radiation-resistant, making them attractive for satellite and terrestrial communication systems requiring a high tolerance to high energy(40MeV) protons.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.4 s.23
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• pp.85-90
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• 2005

We report the phase transition temperatures of the $PbZrO_3$ perovskite nanotubes made by sol-gel template synthesis. The lead zirconate($PbZrO{_3}$) nanotubes were prepared with a chelate sol-gel of zirconium tetrabutoxide($Zr(OBu){_4}$) and leadacetate($Pb(OAc){_2}-3H_2O$). $Whatman^(r)$ anodisc membranes, with a 200nm pore size, served as the template. After removing the template in the 6M-NaOH solution, the $PbZrO{_3}$ nanotubes so far have shown an anomalous transition temperature, $123.6^{\circ}C$ as measured by DSC with a small particle size, 15.4nm determined by X-ray analysis with the aid of Scherrer's equation.