• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.1
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• pp.74-80
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• 2013

In this paper, we have proposed a vapor cycle refrigeration system as a cooling system to provide cooling air to the aircraft external reconnaissance stores. In the proposed vapor cycle system, receiver which prevents refrigerant from subcooling was eliminated and thermal expansion valve was replaced with electronic expansion valve. The vapor cycle refrigeration system is aimed to provide cooling air to the reconnaissance stores which is added to the aircraft in the form of external store. The wide temperature range of ambient air from the flight conditions can decrease the cooling performance and can make the refrigeration system unstable in low ambient temperature. Performance characteristics of the vapor cycle refrigeration system has been experimented under air conditions which is derived from the flight envelope. From the experiments, the vapor cycle refrigeration system has been proved to provide enough cooling air to the reconnaissance equipment and to be stable under all the flight conditions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.72-80
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• 2023

Line Operations Safety Audit (LOSA) is a well known preventive aviation safety program for Threat and Error management (TEM). High quality LOSA data suitable for safety management is obtained when a flight crew flies at the same level of attention as ordinary flight. Factors contributing to LOSA data quality may include flight crew's understanding on LOSA purpose, observer's career, and characteristics of the organization responsible for LOSA operations. This study explored purposes of TEM and LOSA, as well as their relationship. Previous studies mentioned quality of LOSA data can be influenced by heuristic judgment, hawthorne effect, and priming effect. This study recognized the importance of LOSA data quality to be effectively used for preventive safety management. It was confirmed that the level of understanding on LOSA concept, experience of the observer, and the characteristics of the department in charge of LOSA operation could affect the quality of LOSA data.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.703-710
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• 2001

The nonlinear observers are proposed for a nonlinear system. To improve the characteristics such as stability, convergence, and $H^{\infty}$ filter performance criterion, we utilize an $H^{\infty}$ filter Riccati equation or a modified $H^{\infty}$ filter Riccati equation with a freedom parameter. Using the Lyapunov function method, the characteristics of the observers are analyzed. Then the in-flight alignment for a strapdown inertial navigation system(SDINS) is designed using the proposed observer. And the additive quaternion error model is especially used to reduce the uncertainty of the SDINS error model. Simulation results show that the observer with the modified $H^{\infty}$ filter Riccati equation effectively improves the performance of the in-flight alignment.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.135-141
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• 2024

Despite the innovative technological advances in the aviation industry, hard landing events that occur during aircraft landing account for 13% of all accidents. Hard landing when landing an aircraft affects normal operation by generating a large load on the landing gear and the fuselage. In order to identify these risk factors, the airline monitors the high vertical acceleration event, a precursor to hard landing, through QAR (Quick Access Recorder) flight data analysis, and prepares and implements mitigation measures. In this study, it is intended to contribute to safety management based on flight data analysis that identifies the characteristics of high vertical acceleration G event data that can cause such hard landing and detailed parameters of precursor signs, and to identify the causal relationship of the occurrence of the event by applying statistical analysis methods such as variance analysis, correlation analysis, and regression analysis models to identify the characteristics of the event occurrence and eliminate the cause in advance.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.4
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• pp.1-23
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• 2017

Organizational culture among flight crews has a profound impact on the individual attitude and behavior of member flight crews, and active training is conducted focusing on improving flight crews' Crew Resource Management(CRM) performance. However, adequate research and training on the relationships between flight crew's individual culture and CRM performance have not been conducted. Hence, this study examined the effect of individual cultural values on CRM performance and the moderation effect of psychological safety, with captains and first officers working for commercial airlines as participants. For the factors related to individual cultural value scale, power distance had no significant effect on CRM performance, uncertainty avoidance had a significant negative effect, and individualism had a significant positive effect. With regard to the moderation effect of psychological safety on the relationships between individual cultural values and CRM performance, a significant interaction was found between power distance and CRM performance, but not between uncertainty avoidance and CRM performance, or between individualism and CRM performance. Power distance and CRM performance exhibited a strong negative correlation in case of low psychological safety. Compared to existing research measuring the cultural characteristics of pilot groups on a national or organizational culture level, this study is uniquely valuable in that it also covers the relationship between individual cultural values of commercial airline flight crews and CRM performance.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.29-37
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• 2011

Last April, Europe was severly damaged as all social and economic activities came to a halt prompted by the cancellation of all flights resulting from volcanic ash. This exemplifies that the meteorology conditions have significant influence on the flights of airplanes. Hence, in this research the influence that the meteorology has on the domestic flights and its characteristics will be examined, and the core meteorological factors that influence flights in each airport will be drawn. In order to do this, statistical analysis on the influence that the meteorology has on flights was carried out in order to analyze the data about flight cancelation and delay and also its cause, primarily based on the Gimpo, Gimhae, and the Jeju airports. As a result, first, the meteorological factors which impact flight cancellation and delay were different among the domestic airports, and second, it was analyzed that fog was the main meteorological factor in the Gimpo airport, strong wind in the Jeju airport, and fog in the Gimhae airport. Third, between the day the flights were cancelled and delayed occurred, and the day that weren't, the fact that there existed a difference among the actual meteorological factors was statistically drawn. With the result of such analysis, meteorological factors pertaining to the cancellation and delay of flights must be considered seperately by each airport and specialized meteorological information must be provided accordingly. Further, when selecting the position of an airport that is to be constructed in the future, implications that there is a definite need for the meteorology effect evaluation based on past meteorology data can be drawn.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7013-7020
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• 2015

The purpose of the study was to explore quality of sleep, fatigue and job stress and to identify related factors in airlines international flight attendants. The major findings of this study were as follows: 1) Significant factors of job stress by Subject Characteristics were gender(t=-4.14, p<.001), position(F=3.47, p=.011), monthly flight time(F=3.70, p=.028), health supplements(t=3.66, p<.001), sleeping pills(t=4.27, p<.001). 2) A statistically significant relationship between quality of sleep(r=-.57, p<.001), fatigue(r=.61, p<.001) and job stress. 3) The results of the regression analyses showed that fatigue, sleeping pills, gender, quality of sleep were statistically significant in predicting airlines international flight attendants' job stress. The result of this review provide a better understanding of quality of sleep, fatigue and job stress in airlines international flight attendants.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.22-31
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• 2005

A design study was conducted for a new concept aircraft(Canard Rotor/Wing: CRW) that has the capability of dual mode flight, a rotorcraft and a fixed wing mode. The CRW can show a vertical take off/landing and a high speed/efficiency cruise performance simultaneously. It is not surprising to develop a new sizing code for this class of aircraft because conventional sizing codes developed solely for either the rotary wing or the fixed wing aircraft are not adequate to design a dual mode aircraft operated both by the rotary wing through tip jet effux and the fixed wing lift. Thus, a new design code was developed based on the conventional sizing code by adding some features including rotor performance, duct flow, and engine flow analysis, hence could eventually predict the performance of reaction driven rotor, the flight performance and the flight characteristics. The various design parameters were investigated to find their influences on the flight performance then, a small UAV(Unmanned Aircraft Vehicle) of 1500 lbs class was optimally designed to have minimum weight using the developed sizing code.

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.249-260
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• 2022

Student pilots receiving flight education are inexperienced in piloting and situation judgment skills and are greatly affected by various factors such as psychological, physical, and environmental factors. In particular, one of the most influential factors in the flight education of student pilots is the weather conditions. Unlike large aircraft used in the air transportation business, small aircraft used for flight education have a great impact on education, such as flight restrictions depending on weather conditions, psychological pressure in severe weather, and deterioration of student skills. Therefore, in this study, the meteorological characteristics of meteorological factors that have a great influence on small aircraft were analyzed. As a result of the analysis, an efficient and safe training operation method was suggested to a professional pilot aviation training organization through the adjustment of the training period for the season, the increase in aircraft operation rate, and a safe solo flight plan considering the weather.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.634-642
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• 2011

A numerical analysis of steady/unsteady flow applying cavitation model and moving mesh method was carried out in order to analyze flow and response characteristics inside the pilot valve which controls the flight actuator system. The flow of the valve was assessed according to operation temperature and time. This research has found that valve characteristics became stable at above a specific temperature and the cavitation affected valve's performance. Internal pressure and response characteristics of the valve were analyzed and flow characteristics of steady and developed unsteady flow were confirmed to be matched each other.