• 한국항공우주학회지
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• 제35권4호
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• pp.347-352
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• 2007

논문에서는 과학기술위성 2호용으로 개발된 탑재체데이터 수신시스템(Data Receiving Equipment, DRE)을 소개하고 개발된 준비행모델(Proto Flight Model, PFM)에서의 기능 및 성능 시험 결과를 제시 한다. 탑재체데이터 수신시스템은 X 대역 수신기, 데이터 합성장치(Data Combine Equipment, DCE)와 수신 저장 컴퓨터(Receiving and Archiving Computer, RAC)로 구성되어 있다. DCE는 I&Q 신호 합성기와 ECL 신호 분배기로 구성 된다. RAC은 데이터 수신 카드(Data Receiving Card, DRC)와 소프트웨어인 ST2RAS(STSAT-2 Receiving and Archiving Software, ST2RAS)로 구성된다. X 대역 수신기를 통해서 수신된 I, Q 데이터는 DCE를 통해서 I&Q 데이터로 합성된다. 합성된 데이터는 데이터 수신 카드를 통해서 수신 저장 컴퓨터의 RAID(Redundant Array of Inexpensive Disk)에 저장되고, 이 데이터는 ST2RAS의 전처리를 통해서 위성의 상태 정보와 탑재체 정보로 분리된다. 탑재체데이터 수신시스템에 대한 기능 시험과 열진공 시험을 통해서 10-6 의 BER(Bit Error Rate) 요구사항을 만족하는 결과를 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제14권2호
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• pp.355-366
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• 1997

This paper presents a comprehensive analytical approach for determining key maneuver parameters associated with the acquisition and maintenance of the ground track for a low-earth orbit. A livearized model relating changes in the drift rate of the ground track directly to changes in the orbital semi-major axis is also developed. The effect of terrestrial atmospheric drag on the semi-major axis is also explored, being quantified through an analytical expression for the decay rate as a function of density. The non-singular Lagrange planetary equations, further simplified for nearly circular orbits, provide the desired relationships between the corrective in-plane impulsive velocity increments and the corresponding effects on the orbit elements. The resulting solution strategy offers excellent insight into the dynamics affecting the timing, magnitude, and frequency of these maneuvers. Simulations are executed for the ground track acquisition and maintenance maneuver as a pre-flight planning and analysis.

• International Journal of Aeronautical and Space Sciences
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• 제6권2호
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• pp.33-45
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• 2005

The 1/9-scale model of a fighter-type configuration was tested in the Micro-Craft 8ft ${\times}$ 12ft wind tunnel facility. An abrupt lift dump was found at a certain range of angle of attack under the pre-scheduled approach configuration. To avoid a probable unsatisfactory flight behavior due to the lift dump, various aerodynamic devices were suggested. Extensive tests applying the cutoff leading edge flaps, boundary layer fences, saw tooth and vortex generators were performed with flow visualization as well as force and moment measurements. Test results showed that the origin of the lift dump was caused by the secondary boundary layer flow separation generated from the strong interaction between wing and flap. Various solutions for avoiding the unfavorable feature were suggested with the merits and demerits.

• Journal of Magnetics
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• 제18권2호
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• pp.90-94
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• 2013

We designed a model composed of a ring type magnet, a yoke, and a sensing coil embedded in a projectile for simulating the muzzle velocity. The muzzle velocity was obtained from the master curve for the induced voltage at sensing coil and the velocity as the projectile pass through the magnetic field. The induced voltage and the projectile's velocity are fitted by the $2^{nd}$ order polynomial. The skin effect difference between projectiles which consist of aluminum-aluminum and aluminum-steel was small. The projectile will surely be burst at the pre-determined target area using the flight time and the projectile muzzle velocity calculated from the voltage induced at the sensing coil on the projectile.

• 스마트미디어저널
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• 제12권1호
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• pp.32-46
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• 2023

Natural Language Processing (NLP) has grown tremendously in recent years. Typically, bilingual, and multilingual translation models have been deployed widely in machine translation and gained vast attention from the research community. On the contrary, few studies have focused on translating between spoken and sign languages, especially non-English languages. Prior works on Sign Language Translation (SLT) have shown that a mid-level sign gloss representation enhances translation performance. Therefore, this study presents a new large-scale Korean sign language dataset, the Museum-Commentary Korean Sign Gloss (MCKSG) dataset, including 3828 pairs of Korean sentences and their corresponding sign glosses used in Museum-Commentary contexts. In addition, we propose a translation framework based on self-supervised learning, where the pretext task is a text-to-text from a Korean sentence to its back-translation versions, then the pre-trained network will be fine-tuned on the MCKSG dataset. Using self-supervised learning help to overcome the drawback of a shortage of sign language data. Through experimental results, our proposed model outperforms a baseline BERT model by 6.22%.

• 한국항공운항학회지
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• 제23권1호
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• pp.41-48
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• 2015

Being a cost-efficient solution for alleviating the traffic congestion in airspace, Air Traffic Flow Management (ATFM) has drawn more attentions from not only air traffic controllers but also researchers in the field of Air Traffic Management (ATM). Among other ATFM initiatives, it is believed that Ground Delay Program (GDP) could be effectively applied to reduce the congestion particularly in the relatively small airspace with dense traffic demand. This paper introduces a novel way that suggests flights to be delayed on the departing airports together with amount of the delays (in time) for those flights to be delayed. Adopting a fast-time simulation for predicting airspace delay of each flight for a given flight plan, the method is designed to iteratively and incrementally adjust the departure times in the plan towards reducing total airspace delays. Applying the method to Jeju airport with a hypothetically high demand, the paper demonstrates the airspace delay could be significantly reduced by applying GDP at Gimpo airport where more than 60% of Juju-bound flights departure. Although the simulation model needs to be calibrated and validated for the real-world application, the results clearly shows that the approach can possibly implemented as a tool for preparing the daily plan at the pre-tactical stage defined in the ICAO ATFM manual.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.239-242
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• 2016

최근에, UAV는 위험하거나 파일럿이 필요하지 않는 지역인 군사 또는 민간 활동으로 부터 발전되어 왔다. 하지만, UAV는 감시활동 또는 어떠한 지역 이미지/영상을 찍는 것과 같은 그것의 임무 활동 능력에 높은 요구가 필요하다. 그러므로, 무사히 임무완료하는 UAV로 부터 파워 소비량을 줄이는 기법의 방아쇠가 필요한 상황이다. 방법중 하나는 소비량 파워를 낮추는 적합한 이 웨이포인트를 통해 비행하는 최소한의 길을 찾는 웨이포인트의 사전지정을 가짐으로써 나누어 주는 최적한 절차 웨이포인트를 사용한다. 본 논문은 UAV에 기인하는 항공우주 산업 패케지 분석연구, Aerosim Blockset 그리고 UAV에 사용되는 MATLAB Simulink의 디자인 시뮬레이션 모델, 분석적인 모델로 대표적인 불가능을 만드는 여러 학문 분야에 걸친다. 그 시뮬레이션 모델은 UAV로부터 최소화 될수 있는 파워소비 백분율에 측정되는 순서에 웨이포인트(비행경로)를 가지는 알고리즘을 따라 좀더 최적화 연결을 한다.

• 제어로봇시스템학회논문지
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• 제15권8호
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• pp.859-866
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• 2009

The article discusses an issue of estimating the airspeed of an autonomous flying vehicle. Airspeed is the difference between ground speed and wind speed. It is desirable to know any two among the three speeds for navigation, guidance and control of an autonomous vehicle. For example, ground speed and position are used to guide a vehicle to a target point and wind speed and airspeed are used to maximize flight performance such as a gliding range. However, the target vehicle has not an airspeed sensor but a ground speed sensor (GPS/INS). So airspeed or wind speed has to be estimated. Here, airspeed is to be estimated. A vehicle's dynamics and its dynamic parameters are used to estimate airspeed with attitude and angular speed measurements. Kalman filter is used for the estimation. There are also two major sources arousing a robust estimation problem; wind speed and altitude. Wind speed and direction depend on weather conditions. Altitude changes as a vehicle glides down to the ground. For one reference altitude, multiple model Kalman filters are pre-designed based on several reference airspeeds. We call this group of filters as a cluster. Filters of a cluster are activated simultaneously and probabilities are calculated for each filter. The probability indicates how much a filter matches with measurements. The final airspeed estimate is calculated by summing all estimates multiplied by probabilities. As a vehicle glides down to the ground, other clusters that have been designed based on other reference altitudes are activated. Some numerical simulations verify that the proposed method is effective to estimate airspeed.

• 융합정보논문지
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• 제9권4호
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• pp.68-77
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• 2019

본 연구는 기내안전정보에 관한 승객 인지에 대해 행동이론을 적용하였으며, 이를 통하여 안전행동 의도에 미치는 영향을 분석하고자 하였다. 또한, 대표적인 소비자 행동이론인 계획된 행동이론과 트라이앤디스 행동이론의 비교를 통해 기내안전정보 인지에 따른 안전행동 의도를 설명하기 위한 모형의 특징파악을 목적으로 하고 있다. 연구목적을 달성하기 위해 선행연구를 토대로 연구모형과 가설을 수립하였으며, 370명의 항공여행을 경험한 승객을 대상으로 설문을 통해 경로분석을 실시하였다. 분석 결과, 계획된 행동이론은 태도와 지각된 통제가 안전행동 의도에 긍정적 영향을 미치는 것으로 나타났으며, 트라이앤디스 이론은 사회적 영향과 습관이 안전행동 의도에 긍정적인 영향을 미치는 것으로 나타났다. 또한, 두 모형의 비교를 통해 기내안전정보 인식과 안전행동 의도의 관계에서 인식과 감정의 심리적 과정이 모두 동반된다는 점을 확인하였다.

• 한국정보통신학회논문지
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• 제25권2호
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• pp.187-192
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• 2021

본 연구는 객체 검출기를 이용하여 숲 혹은 그에 준하는 복잡한 환경에서의 이륙에 대한 시스템을 제안한다. 시뮬레이터에서 대각선상의 모터간 550mm의 길이를 갖는 쿼드콥터에 라즈베리파이를 장착하여 엣지 컴퓨팅 기반으로 실험을 진행한다. 학습에 사용될 이미지는 군산대학교 내부의 세 지점을 선정하여 640⁎480 사이즈의 이미지를 150장 내외 정도 획득하였으며, 이들을 흑백으로 변환한 다음, 127의 경계값을 두어 이진화 전처리를 하였다. 이후 SSD_Inception 모델을 학습 하였다. 시뮬레이션상에서 검증용 영상을 입력으로 학습한 모델을 통해 드론을 이륙시키는 실험 결과, 라벨을 이용하여 이륙했을 때와 유사한 궤적을 그려내었다.