• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.167-171
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• 2012

A computational analysis of nozzle flow is conducted to investigate effects of the flight altitude on thrust performance. Reynolds-averaged Navier-Stokes equation with k-${\omega}$ SST(Shear Stress Transport) turbulence model is employed to simulate the nozzle flow in various altitude conditions, where continuum mechanics is to be valid. Thrust performance of the nozzle is exceedingly poor upto 10 km of flight altitude because of the irreversible phenomena such as shock and/or flow separation occurring inside the nozzle, whereas it is restored to the nominal value as the altitude is attained higher than 30 km.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제8권1호
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• pp.57-69
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• 1997

Objective：At the present time in Korea, for a considerable proportion of children and adolescent, delinquent behavior and violence has become as a way of life in their lives and a major social problem issue as well. The contributing factors to this problem were assumed to be the negative interaction between family environment and character of adolescent. The purpose of this study is to search the relationship between these constructs and juvenile delinquency. Method：Data were collected through questionnaire survey over a period of 2 months. Subjects served for this study consisted of 1,863 adolescents including 657 delinquent adolescents and 1,206 student adolescents in Korea, sampled from Korean student population and delinquent adolescent population confined in juvenile corrective institutions, using proportional stratified random sampling method. Their age ranged between 12 and 18 years. Data were analysed by IBM PC using SAS program. Statistical methods employed were Chi-square and principal component analysis. Results：The results of this study were as follows：Inconsistency by parental child rearing patterns tended to affect delinquent behavior among delinquent adolescents. On the other hand, adolescent students were consistently reared by their parent with democratic, flexible, trusting their children and reward-oriented attitudes. In comparison of both parents in the degree of influence on their children, it was revealed that paternal child rearing pattern was more influential on their children’s behaviors than maternal’s. The psychological instability of family, disharmonious parent-child relationships tended to be contributing to delinquent behavior among delinquent adolescents. Especially, It was an interesting finding that student’s mother is the higher employed than delinquent’s mother. However working mother was more prevalent in the student’ adolescents than in student adolescents in previous studies. The delinquent adolescents have more depressive trend, more complaints of psychosomatic symptoms, the higher degree of need frustration, the more maladaptive and antisocial personality pattern than student adolescents. Conclusion：Recently, many studies on association between family factor, character of adolescent and juvenile delinquent behavior have produced relatively consistent results. This study showed that family environment and character trait of adolescent also were linked with delinquent behavior such as smoking, drinking, runaway and physical assaults etc. The results of this survey may provide impetus for future speculation and study of correlation or reciprocal interaction between family factor, character trait of adolescent and delinquent behavior during adolescence and beyond.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제40권8호
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• pp.678-687
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• 2012

The Fly-By-Wire(FBW) flight control system is essential to improve the stability and flying quality of the helicopter. Advanced aerospace companies, such as Bell-Sikorsky (USA) and NHI (European Consortium), have already applied the FBW flight control system to manufacture V-22 and NH-90 helicopters, respectively. This paper addresses the development of control law design using model inversion method improve the hover and low speed handling qualities of helicopter based on BO-105 model in 'Day' and 'Degraded visual environments(DVEs)' in accordance with ADS-33E-PRF. Design parameters are optimized to satisfy the handling qualities specification using Control Designer's Unified Interface (CONDUIT) commercial control law software. The result of the analysis based on CONDUIT and non-real time simulation in-house software, HETLAS (HElicopter Trim Linearization And Simulation) reveals that the provides an efficient mean to achieve Level 1 handling qualities.

• Journal of Aerospace System Engineering
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• 제18권4호
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• pp.18-26
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• 2024

This paper describes the results of a study on Generic Quad Tilt Rotor UAM aircraft, focusing on nonlinear mathematical modeling and the development of real-time simulation software. In this research, we designed a configuration for a Generic Quad Tilt Rotor eVTOL UAM aircraft based on NASA's UAM mission requirements. We modeled the aerodynamics using a database, the prop-rotor dynamics with a thrust database, and included a ground reaction and atmospheric model in the flight model. We defined the control concept for various modes(helicopter mode, transition mode, and airplane mode), derived tilt angle corridors, and formulated flight control requirements. The resultant real-time flight simulation software not only performs trim analysis for Tilt Rotor UAM aircraft but also predicts handling qualities, optimizes tilt angle scheduling based on dynamic characteristics, designs and validates flight control laws for helicopter, transition, and airplane modes, and facilitates flight training through simulator integration.

• Journal of the Korea Society of Computer and Information
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• 제28권8호
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• pp.111-118
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• 2023

In this paper, we propose a WiFi-based joystick with an acceleration sensor and a vibration sensor that can be used in flight simulators and VR fields. The flight simulator is a technology belonging to the ICT and SW application field and provides a simulation environment that reproduces the aircraft environment. Existing flight simulator control devices are fixed to a specific device and the user's activity area is limited. In this paper, a 3D space manipulation device was implemented for the user's free use of space. In addition, the proposed control device is designed as a WiFi communication board and display that displays information and performs 3-axis sensing for accurate and sophisticated control compared to existing VR equipment controllers. And the applicability was confirmed by implementing a Unity-based virtual environment. As a result of the implementation device verification, it was confirmed that the control device operates normally through the communication interface, It was confirmed that the sensing values in the game and the sensing values measured on the implemented board matched each other. The results of this study can be used for VR and various metaverse related contents in addition to flight simulators.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제47권5호
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• pp.326-334
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• 2019

Development of Small UAV using HILS (Hardware In the Loop Simulation) can be effectively used to improve the reliability of UAV (Unmanned Aerial Vehicle) while reducing cost and time. It is also possible to reduce the damage to people or property by simulating the malfunction of the Flight Control Computer (FCC) that may occur during the actual flight. For applying such HILS, a real-time simulation environment capable of providing an environment similar to an actual flight condition is required. In this paper, we constructed a real - time HILS environment for Small UAV using 6 D.O.F motion table. In order to link the 6 D.O.F motion table developed in the previous research with the HILS environment in real time, the motion algorithm was changed from the position control method to the velocity control method. Also, we implemented modeling of inverse kinematics model for command transmission in Matlab $Simulink^{(R)}$ and verified the action of motion table according to the simulation model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제45권5호
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• pp.359-366
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• 2017

In this paper, aerodynamic data of the Gaori kite was constructed through the wind tunnel experiment taking into consideration all the angles of attack formed during the flight of the Gaori kite. From this aerodynamic data, we made a morphing analysis of the relative length of the front bridle to the rear bridle required to achieve equilibrium flight as the angle of attack of the Gaori kite or the azimuth angle change. As a result, it was found that the relative length of the front bridle to the rear bridle depends entirely on the chord length of the kite, the relative wind speed and changes morphed according to the angle of attack. Using this information data, one can adjust the relative length of the bridle line to suit the kite attitudes and flight environments handling the kites that maintain optimal flight performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제21권1호
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• pp.90-96
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• 2020

In this era, intelligence is considered a major factor in the defense sector. As a result, securing technology for weapons systems for monitoring and reconnaissance of companies has become inevitable. As a result, UAVs (Unmanned Aerial Vehicles) have been developed and are actively operating around the world if the flight operation of manned aircraft is restricted, such as in environments that are too dangerous, messy or boring for the military to perform directly. The system of unmanned aerial vehicles, which has been researched and developed in Korea, includes Air Vehicle Test Equipment(AVTE). AVTE is equipment that is connected to an UAV to check its status and allows the operator to check its flightability by issuing an operational command to the UAV and verifying that it follows the command values. This study conducts fault finding on the phenomenon where the AVTE has stopped operating due to engine noise during these operations and analyzes the cause in terms of software, hardware and external environment. Present improvement measures according to the cause are analyzed and the results of verifying that the proposed measures can prevent failure are addressed.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2015년도 추계학술대회
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• pp.148-153
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• 2015

최근 발생한 국적항공기의 사고들은 항공기가 정상인 상태에서 조종사의 항공기 시스템에 대한 이해부족과 악 기상에 대한 대처미흡과 함께 운송용 조종사들의 수동착륙 기량이 현저하게 낮은 데에 그 원인을 찾을 수가 있다. 본 연구에서는 운송용 항공기 조종사들에 적용된 훈련프로그램의 실태와 이를 개선하기 위한 국제기구 및 항공선진국의 조치에 대한 문헌 연구와 함께 문제점을 분석하고 그 대안을 제시 하고자 한다. 항공사고 예방에 모의비행장치를 활용한 조종사 교육훈련이 큰 기여를 해온 것은 사실이다. 그러나 다양한 비정상 조건하에서 조종사들의 기량을 확인하기에 적합한 고가의 모의비행장치를 평이한 훈련과목, 환경이 우수한 특급 공항을 선택하여 운영한다는 것은 모의비행훈련의 기본 목적에 부합하지 않으므로 앞으로 조종사들의 기량향상을 위해서는 최악의 상황을 부여하고 안전하게 항공기를 운영하는 역량을 교육하고 평가할 필요가 있다. 또한 데이터에 기반을 둔 조종사 훈련프로그램인 APQ 및 EBT 의 조기 도입을 항공사와 정부가 협력하여 추진할 경우 국적항공사 소속 운송용 조종사들에게 비정밀 접근, 수동착륙 환경에서도 자신감 있게 항공기를 운영할 수 있는 경쟁력을 제공할 수 있을 것으로 판단된다.

• Current Industrial and Technological Trends in Aerospace
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• 제8권1호
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• pp.96-103
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• 2010

The propulsion systems such as upper stages of launch vehicles, orbiters, spacecrafts have to operate in the zero gravity environment. Because the flight condition where the vehicle undergoes is different from the normal gravity state, many studies have been being in progress. Fluid behavior in the zero gravity condition is differently shown in the normal gravity state because the importance of the intermolecular force, such as adhesion, cohesion, and surface tension is enlarged. In this paper, we investigate the characteristic of fluid behavior and describe effects and problems on the liquid propulsion system due to these fluid behavior. We also check which studies are in progress in order to solve these problems.