• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.84-91
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• 2005

For long time, the takeoff and landing control of airship was worked by human handling. With the development of the autonomous control system, the exact controls during the takeoff and landing were required and lots of methods and algorithms were suggested. This paper presents the result of airship take-off and landing by buoyancy control using air ballonet volume change and performance control of pitch angle for stable flight within the desired altitude. For the complexity of airship's dynamics, firstly, simple PID controller was applied. Due to the various atmospheric conditions, this controller didn't give satisfactory results. Therefore, new control method was designed to reduce rapidly the error between designed trajectory and actual trajectory by learning algorithm using an artificial neural network. Generally, ANN has various weaknesses such as large training time, selection of neuron and hidden layer numbers required to deal with complex problem. To overcome these drawbacks, in this paper, the RBFN (radial basis function network) controller developed. The weight value of RBFN is acquired by learning which to reduce the error between desired input output through and airship dynamics to impress the disturbance. As a result of simulation, the controller using the RBFN is superior to PID controller which maximum error is 15M.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.64-70
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• 2024

The demand for safety certification of Light Unmanned Aerial Vehicles (LUAVs), weighing between 25kg and 150kg, is rapidly increasing in Korea. Unfortunately, the number of LUAV safety certification failures is also on the rise, with manufacturing quality issues being identified as the main culprit. However, there is a lack of quality system standards for manufacturers within the LUAV safety certification system. As a result, this paper aims to analyze the domestic safety certification system and the quality standards set by the American Society for Testing and Materials (ASTM) for small Unmanned Aerial Systems (sUAS). The goal is to establish quality system inspection standards specifically tailored for LUAV manufacturers. To achieve this, we propose additional inspection items that reflect the characteristics of the manufacturing quality system. These items will be identified through on-site inspections of LUAV manufacturers, ensuring that the resulting quality system standard aligns with the actual situation of domestic manufacturers. In order to gauge the feasibility and effectiveness of the proposed quality system standard, we conducted a survey of seven domestic LUAV manufacturers.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.10 no.2
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• pp.201-211
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• 1999

Objectives：This study investigated the characteristics of detained delinquent adolescents and variables related to the repeated crime during 6 months after release. Methods：The socio-demographic and crime-related characteristics of 73 detained adolescents were evaluated by semi-structured interviews and police records, and the psychological characteristics of them measured by the MMPI. We also compared the characteristics between subjects with and without repeated crime during 6 months after release. Results：1) Most of detained adolescents had families with low socioeconomic status(77%) and broken families(48%). Sixty-six percent of them were dropped out of school. The most frequent crime pattern was theft(49%), and with accomplice(77%). Seventy-five percent of total subjects had the records of previous conviction. Of the previous convictions, seventy-eight percent was same with the present crimes. 2) Subjects with repeated crime during 6 months after release were younger and had higher T-score on Pa scale of MMPI than the subjects without repeated crime. More adolescents with repeated crime had broken families than those without repeated crime. They also showed the crime-related characteristics of higher percent of theft among crime patterns, higher incidence of previous conviction, younger age of the first crime, and shorter crime-free duration from the last to present crime. Conclusion：These results of present study suggest that the development and the persistence of adolescent delinquency would be resulted from interaction of factors of individual, family, school, and community. By the comparison between subjects with and without repeated crime, it was found that familial dysfunction, younger age at first crime, presence of previous conviction might be the risk factors for repeated delinquency. To prevent repeated crime of delinquent adolescents more effectively, early therapeutic intervention and the development of programs to help adaptation in school and community would be essential.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.899-907
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• 2022

According to the Unmanned aircraft system Traffic Management (UTM), drones are permitted to fly up to 150m above ground, which is located in the atmospheric boundary layer where there is considerable wind fluctuation due to turbulence. Although it is difficult to predict when turbulence will occur drone aviation safety could be enhanced by having a better understanding of the characteristics of vertical profile of wind in the flight area. We used wind lidar (WIndMast 350M) to observe vertical profiles of wind at the test site for aviation meteorological observation equipment located near Incheon International Airport in July and September, 2022. In this study, we utilized the observed wind profile data to propose a technique for obtaining information that could help improve the drone aviation safety. The Fourier transform analysis is used to evaluate the temporal characteristics of the horizontal wind speed at various vertical levels up to 350m. We also examined the relative contribution of the variance of wind having scales of less than an hour, a crucial scale for drone flight, to the variance of wind having all scales at each vertical altitude for days with and without precipitation.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.222.1-222.1
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• 2016

전북대학교 고온플라즈마응용센터에 구축된 0.4 MW 급 분절형 아크 가열 풍동은 초음속 비행과 우주 비행체의 지구 재진입 조건에서의 유사한 환경 모사가 가능하다. 극한상황에서의 고엔탈피 플라즈마 유동은 내열재료의 삭마 거동 연구와 고온재료의 성능평가에 중요한 역할을 수행 할 수 있다. 이러한 고엔탈피 초음속 플라즈마 유동장의 플라즈마 특성 평가 및 진단은 플라즈마와 내열재료의 상호작용 연구에 중요한 변수를 갖는다. 이를 위해 열유속 탐침, 쐐기 탐침, 고속 카메라 및 광분광기 등의 측정장비를 사용하여 열유속, 초음속 플라즈마의 속도, 플라즈마의 방전특성을 관찰하였다. 본 실험에서 사용된 분절형 아크 토치는 마하 3의 속도 유지하기 위해 토치 내부 압력 4 bar, 반응기 압력 40 mbar를 유지하였다. 토치에 공급되는 Ar(5%)+Air(95%)의 방전기체의 유량은 15 g/s 로 토치에 주입 되었다. 또한, 플라즈마 토치에 가해지는 입력전류는 200A ~ 350A로 10MJ/kg 이상의 엔탈피를 갖는 초음속 플라즈마 유동을 형성하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.905-911
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• 2011

With the progress of micro actuator technology, studies on the development of micro air flapping wing vehicles are actively undergoing. In the present study, the changes of both lift and thrust characteristics of the wings are investigated using a boundary element method. Lift of the heaving wing is not generated when the wing is beating with smaller frequencies than 1 Hz. Thrust increases with amplitude and frequency. As the wing's taper and aspect ratios increase, both lift and thrust also increase. Results on the pitching oscillation and flapping motion will be included in the future work.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.6
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• pp.483-488
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• 2007

The aerodynamic characteristics of FAST(Future Air Speed Transit) combined the body with tandem wing flying over nonplanar ground surface are investigated by using a boundary element method. To validate the present method, results of the present analysis are compared with the experiment and other numerical results. The arrangement of the tandem wing is determined to secure sufficient aero-levitation force and the stability through the analysis of the aerodynamic characteristics of the FAST. The FAST has the maximum lift characteristics when the tandem wing with lower endplate is located at the front side and the rear side of the body. The stability of the FAST can be secured by using the flaperon of the tandem wing.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.11-16
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• 2016

In this paper, an experimental study on the aerodynamic characteristics of a variable span wing flying inside a channel guideway is accomplished using wind tunnel testing. A variable span wing with a NACA 0012 airfoil section was fabricated and actuated using a linear servo motor. The aerodynamic effects of 1) wing aspect ratio, 2) ground effect, and 3) the gap between the wingtip and the wing fence were investigated. It was found that both ground effect and wing fence gap increased lift. Also, the wing fence gap does not significantly affect drag. Therefore, it was found that a variable span mechanism can be used as an effective high lift device when flap use is limited.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.4
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• pp.19-26
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• 2003

In this paper, the result of the conceptual study of a tipjet driven propulsion system is presented. The concept of a tipjet driven propulsion system is to employ tipjet as power source to drive a rotor Because the vehicle is supposed to takeoff and land vertically, a rotor system, which has tipjet nozzles, is adopted to fly like a helicopter. Exhaust gas, which is generated by an engine, Passes through an internal duct system and divided into four blade ducts. The design code is consists of two parts, engine model and internal duct model. Inside a rotating duct, compressible flow is affected by two additional force terms, centrifugal force and coriolis force and they govern the performance in rotary mode, The intention of this paper is to address the issues associated with sizing and optimizing configurations of a tipjet driven propulsion system especially in rotary wing mode.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.295-306
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• 2006

In this paper, we proposed and implemented a novel antenna cover mounted over a microstrip path antenna for ultrafast aircraft. A protective antenna cover prevents alteration in the electrical characteristics of the antenna due to environmental conditions. The permittivity of the cover materials should be practically invariable at all operating frequencies. We evaluated the characteristics of the antenna with both simulation and experiment. The experimental results show that the proposed antenna cover can be useful for ultrafast aircraft.