• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.29-36
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• 2024

Recently, the concept of Urban Air Mobility (UAM) has expanded to Advanced Air Mobility (AAM). A tilt rotor type of vertical take-off and landing aircraft has been actively studied and developed. A tilt-rotor aircraft can perform a transition flight between vertical and horizontal flights. A blade pitch angle control system can be used for flight stability during transition flight time. In addition, Individual Blade Control (IBC) can reduce noise and vibration generated in transition flight. This paper proposed Disturbance Observer Based Control (DOBC) and Time Delay Control (TDC) for individual blade control of an Electro-Mechanical Actuator (EMA) based blade pitch angle control system. To compare and analyze proposed controllers, numerical simulations were conducted with DOBC and TDC.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.852-854
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• 2010

MCM-ERC32 는 우주 환경에서 동작하는 시스템에 사용할 목적으로 유럽에서 개발된 집약 프로세서 모듈이다. MCM (Multi Chip Module)은 크게 ERC32 single chip 과 VASI (Very Advanced Sparc Interface) 및 6MByte 의 SRAM, 32MByte 의 DRAM 으로 구성되어 있다. VASI 의 경우 각종 I/O 처리 및 timer 의 기능을 수행하며 특히 VASI RTC 의 경우 VASI cycle, slot 을 이용하여 다양한 형태의 timer 구현이 가능하다. Timer 의 경우 각종 태스크의 관리와 스케줄링에 사용되는 가장 기본적이며 매우 중요한 요소이다. 위성의 고유 시간 역시 timer 를 활용하여 설계하게 되는데 이 부분이 잘 구현 되어야 정확한 임무 수행 및 위성의 제어가 가능하다. 본 논문에서는 VASI RTC 의 구조와 기능에 대해 설명하고 이를 위성의 고유 시간 운영에 적용하는 방법에 대해 다루도록 하겠다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.563-572
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• 2017

The purpose of the study is to investigate the effect of flight height, flight speed, exposure time of camera shutter and autofocusing on the visual resolution of the image in order to obtain ultra-high resolution images with a GSD less than 1cm. It is also aimed to evaluate the ease of recognition of various types of aerial targets. For this purpose, we measured the visual resolution using a 7952*5304 pixel 35mm CMOS sensor and a 55mm prime lens at 20m intervals from 20m to 120m above ground. As a result, with automatic focusing, the visual resolution is measured 1.1~1.6 times as the theoretical GSD, and without automatic focusing, 1.5~3.5 times. Next, the camera was shot at 80m above ground at a constant flight speed of 5m/s, while reducing the exposure time by 1/2 from 1/60sec to 1/2000sec. Assuming that blur is allowed within 1 pixel, the visual resolution is 1.3~1.5 times larger than the theoretical GSD when the exposure time is kept within the longest exposure time, and 1.4~3.0 times larger when it is not kept. If the aerial targets are printed on A4 paper and they are shot within 80m above ground, the encoded targets can be recognized automatically by commercial software, and various types of general targets and coded ones can be manually recognized with ease.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.11
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• pp.968-973
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• 2014

Optionally Piloted Vehicle is one of the UAV development technology and method, which can provide the economic and efficient unmanned system. Existing manned aircraft is evaluated through much flight operations and it can supply the reliable aircraft platform, engine and subsystems for operation. In addition, OPV can be operated both manned and unmanned vehicle to satisfy the mission requirement. under the certain flight conditions. This paper describes main development procedures for automatic flight control system of OPV and summarizes the technical issues and results.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.590-595
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• 2001

VTree는 개발시간을 감소시키고 실시간 3차원 그래픽스 응용 프로그램의 성능을 향상시키는 객체지향 OpenGl기반 소프트웨어 개발 툴킷으로 비주얼 시뮬레이션과 가상현실 응용프로그램을 빠르게 구현하게 해주는 개발 환경을 제공한다. 이 논문에서는VTree 툴킷에서 제공해주는 다양한 특징들을 소개하고, 이 특징들을 이용하여 구현한 비행 시뮬레이션의 구현과정을 기술한다. 본 연구팀에서 구현한 시뮬레이션의 구현내용은 비행기의 수직 360도 회전비행, 수평 360도 회전비행, 여러 비행기의 교차비행 외에 몇 개의 동작들을 구현하였다. 몇 가지 비행 동작을 구현하는 과정에서 VTree 툴킷을 사용한 방법을 기술하며, 구현과정에서 발생된 몇 가지 문제점들과 향후 연구과제를 소개하는 것이 이 논문의 목적이다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.426-432
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• 2017

An experimental and numerical study on shock attenuation in a solid by a subminiature flyer impact was conducted to determine the performance of a subminiature exploding foil initiator such as, flyer velocity and impulse loading. The obtained attenuation pattern shows the possibility to determine the critical flyer velocity for initiating the miniaturized pyrotechnic unit by figuring out shock intensity and duration according to flight characteristics.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.441-444
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• 2008

효과적인 조종사의 임무수행을 지원하는 소프트웨어인 비행임무지원체계가 현대 항공작전의 필수 요소로 주목 받고 있다. 첨단 항공기를 위한 비행임무지원체계의 개발을 위해서는 많은 시간과 비용이 소요되며 높은 개발수준을 요구하고 있으나, 국내 실정은 기본 프레임워크 조차 없는 단일 응용 프로그램 개발 수준에 불과하다. 따라서 차기 항공기를 지원하는 향상된 한국형 비행임무지원 체계를 개발함에 있어, 재사용이 가능하며 품질을 향상시켜줄 수 있는 프레임워크의 개발은 매우 중요한 과제이다. 이에 본 논문에서는 한국형 비행임무지원체계의 개발에 적합한 개발 프로세스를 제시하고, 이에 따른 비행임무지원체계의 프레임워크의 설계 및 개발 방향을 제시하고자 한다.

• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.553-563
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• 2009

This study was conducted to analyze the changes in the echolocation of Pipistrellus abramus according to environmental characteristics. The survey was conducted in the day-roosting site of P. abramus located in Gyeongju City (North Gyeongsang Province) from April to August, 2009. The environmental characteristics during the research were classified in six categories: the emergence time after sunset moving time from day roost to feeding areas; rice fields; forest edges; open spaces; and residential areas. Analysis results showed that there are differences in environmental characteristics and also differences between the moving time to the habitat and the moving time to capture preys. At the emergence time from day roost, Pipistrellus abramus used a FM signal with a short pulse-duration. In open spaces, however, they used a CF signal with a long pulse-duration. In different environmental situations, they used both FM and CF signals, although the types of pulse which they used were different. Except pulse-duration, there were significant differences in pulse-interval, peak-frequency, starting-frequency and ending-frequency between the movement among habitats and the movement to capture preys. Except the emergence time from day-roost, they showed a narrow band FM signal and a long pulse-duration that are suitable to search for insects by sensing echoes of insects when they moved among their habitats. When they were out to capture their preys, they showed a broad band FM signal and a short pulse-duration which enabled them to widely search and accurately locate their preys.

• Science of Emotion and Sensibility
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• v.12 no.1
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• pp.55-64
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• 2009

Previous research has mainly investigated the characteristics of expertise by using typical and routine tasks. This research to overcome these limitations included non-routine task situations and observed expert and novice pilots' situation awareness (SA) performance in routine and non-routine situations. Additionally, whether the ability to aware or perceive the environmental information in limited time varies with the level of expertise was tested. To this end, $2^*2^*2$ mixed factorial design was employed, including expertise (novice/expert) as a between-subjects variable and normality of fight situation (routine/non-routine) and stimulus display time (long/short) as within-subjects variables. As results, there was no performance difference in routine situations between experts and novices, while experts significantly outperformed novices in non-routine situations. When the display time became shorter, overall SA accuracy was decreased for both experts and novices, whereas experts' performance remained significantly higher than novices in short and long conditions. When we examined the interaction between the normality of fight situation and stimulus display time, there was no difference between experts and novices in routine situations for both short and long conditions. In non-routine situations, however, experts' SA accuracy was significantly higher than novices both in short and long conditions. Overall, non-routineness of flight situation does not have any impact on SA performance of experts, while it has a critical impact on SA performance of novices.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.369-374
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• 2007

Unsteady aerodynamic characteristics of the wing with flaperon flying over nonplanar ground surface are investigated using a boundary-element method. The time-stepping method is used to simulate the wake shape according to the motion of the wing and flaperon over the surface or in the channel. The aerodynamic coefficient according to the periodic motion of the flaperon is shown as the shape of loop. The rolling moment coefficient of the wing flying in the channel is same as that of the wing flying over the ground surface. The variation range of pitching moment is wider when the wing flies in the channel than over the ground surface. The present method can provide various aerodynamic derivatives to secure the stability of superhigh speed vehicle flying over nonplanar ground surface using the present method.