• 한국항행학회논문지
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• 제15권6호
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• pp.946-952
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• 2011

항공관제 시에 음성통신의 사용은 정보전달의 부정확성과 주파수 측면에서 채널 점유시간을 증가시키는 문제점을 가지고 있다. 이를 개선하기 위하여 ICAO는 디지털 음성통신과 항공관제에 보다 효과적인 ADS-B 시스템 구축을 제안하고 있다. ICAO는 지정된 ADS-B IN, OUT 데이터 외에 추가적인 파라미터를 통한 효율성 개선에도 많은 연구를 수행하고 있다. 이에, 본 논문은 국내 ADS-B 도입을 위한 기반 연구로 항공관제 시에 음성통신량을 줄이고자 항공관제 음성통신 내역을 분석하였으며, 시뮬레이션을 통해 ADS-B 환경에서 목적고도의 제공 유무에 따라 관제사와 조종사 사이의 음성통신량에 있어서 어떠한 효과가 있는지 비교 분석하였다. 분석 결과 제시한 목적고도 파라미터를 추가할 때 기존 환경보다 음성통신량이 현저히 감소함을 확인하였다.

• Plant Resources
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• 제2권2호
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• pp.113-126
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• 1999

Through the research of tracheophytes type around Mt. Daedun, we are aiming at figuring out the habitat condition of useful resource plants by the classification of vegetation units and communities using the Z-M phyto-sociological method in the basis of the traits of species composition and by the analysis of vegetation and environment by way of coincidence method. Tracheophytes in our research sites was classifid into 117 family, 475 genus 797, species 102 variety,18 breed, in total to 917 kinds. The forest around Mt. Daedun district was classified into 6 communities, 12 groups, 2 sub-groups according to feature species group, differential species group and differential. Judging the result from the examination of community classification factors by the coincidence method, vegetation unit was decided by altitude and topography.

• 융합정보논문지
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• 제10권10호
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• pp.123-127
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• 2020

야간 중대형 산불의 전체적인 화선정보를 얻기 위하여 누락되는 산불에 대한 반복적인 임무비행과 임무수행 종료 후 획득되는 정사영상 정합에 대한 소요시간을 줄이기 위하여 실시간 동영상으로 산불발생 여부를 판단하고 드론의 위치와 영상카메라의 각도정보, 지도상의 고도정보를 활용하여 판단된 산불위치를 계산하여 지도에 도시할 수 있는 지상통제시스템을 개발하였다. 개발된 기능의 신뢰성을 검증하기 위하여 비행고도 별, 영상카메라의 지향하는 위치정보의 오차거리를 측정하였으며, 신뢰할 수 있는 범위내의 위치정보를 지도에 표시하였다. 본 논문에 개발된 기능으로 다수의 산불 발생위치를 실시간 식별이 가능하므로 산불 진화대책 수립을 위한 전체적인 화선정보를 보다 신속하게 획득할 수 있을 것으로 예상된다.

• Current Optics and Photonics
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• 제2권1호
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• pp.7-14
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• 2018

As a sophisticated detection technology, LIDAR has been widely employed to probe low-altitude windshear. Due to the drawbacks of the traditional ramp algorithm, the alarm accuracy of the LIDAR has not been satisfactory. Aiming at settling this matter, a novel method is proposed on the basis of improved signal smoothing and second windshear detection, which essentially acts as a combination of ramp algorithm and segmentation approach, involving the human factor as well as signal fluctuations. Experiments on the real and artificial signals verify our approach.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1224-1242
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• 2018

Aiming at motion analysis and compensation, it is essential to conduct motion detection with images. However, motion detection and tracking from low-altitude images obtained from an unmanned aerial system may pose many challenges due to degraded image quality caused by platform motion, image instability and illumination fluctuation. This research tackles these challenges by proposing a modified joint transform correlation algorithm which includes two preprocessing strategies. In spatial domain, a modified fuzzy edge detection method is proposed for preprocessing the input images. In frequency domain, to eliminate the disturbance of self-correlation items, the cross-correlation items are extracted from joint power spectrum output plane. The effectiveness and accuracy of the algorithm has been tested and evaluated by both simulation and real datasets in this research. The simulation experiments show that the proposed approach can derive satisfactory peaks of cross-correlation and achieve detection accuracy of displacement vectors with no more than 0.03pixel for image pairs with displacement smaller than 20pixels, when addition of image motion blurring in the range of 0~10pixel and 0.002variance of additive Gaussian noise. Moreover,this paper proposes quantitative analysis approach using tri-image pairs from real datasets and the experimental results show that detection accuracy can be achieved with sub-pixel level even if the sampling frequency can only attain 50 frames per second.

• 한국항행학회논문지
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• 제11권2호
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• pp.137-145
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• 2007

본 논문에서의 ADS-B 비행시험은 CDTI상에 목적고도가 제공될 경우 항공교통관제사 및 조종사에게 운영상 어떠한 효과가 있는지를 실증하고자 시행되었다. 또한 이 비행시험은 현 항공교통관제업무 환경에서 ADS-B 운영시험을 하는 최초의 연구이자 향후 우리나라에 ADS-B의 배치를 고려하기 전에 운영상의 실질적인 정보를 제공하기 위한 연구이다. 비행시험을 위해 ADS-B 장비가 탑재된 H 대학교의 항공기 2대가 이용되었고, 충남 태안소재 태안비행장에 지상국이 구축되어, 기 설정된 비행절차에 따라 비행시험이 수행되었다. ADS-B 비행시험 결과 통신주파수 사용횟수 및 주파수 점유시간이 기존의 시스템에 비해 현저하게 줄어듦을 확인하였고, 따라서 항공교통관제사의 업무량(workload) 뿐만 아니라 조종사의 상황인식도 뚜렷하게 개선되어짐을 확인할 수 있었다.

• 한국환경복원기술학회지
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• 제12권4호
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• pp.11-22
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• 2009

This was a 2nd-year study aiming at developing the procedure of alternative system that was intended to restore not only biophysically disturbed areas but also psychologically and socially damaged community. It was suggested that this participatory restoration system could be constructed based on integrative categorization processes consisting of damage types and readiness of local residents for participation. Three case study sites-High-One resort, Lafarge-Halla cement, and high-altitude farmland near Gangneung city, were selected to apply the theoretical framework proposed as a result of 1st-year work. In order to develop introductory programs, key concepts such as forest for future, carbon offset forest, and healing forest, have been suggested based on analysis of 6 system components including human resources, communication, legal and institutional support, financial sources, restoration methods, and activity programs for each site. More detailed processes and procedures can be identified, defined, and refined after the end of final, 3rd-stage of the study in April of 2010.

• Journal of Astronomy and Space Sciences
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• 제33권4호
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• pp.323-333
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• 2016

In this study, the uncertainty requirements for orbit, attitude, and burn performance were estimated and analyzed for the execution of the $1^{st}$ lunar orbit insertion (LOI) maneuver of the Korea Pathfinder Lunar Orbiter (KPLO) mission. During the early design phase of the system, associate analysis is an essential design factor as the $1^{st}$ LOI maneuver is the largest burn that utilizes the onboard propulsion system; the success of the lunar capture is directly affected by the performance achieved. For the analysis, the spacecraft is assumed to have already approached the periselene with a hyperbolic arrival trajectory around the moon. In addition, diverse arrival conditions and mission constraints were considered, such as varying periselene approach velocity, altitude, and orbital period of the capture orbit after execution of the $1^{st}$ LOI maneuver. The current analysis assumed an impulsive LOI maneuver, and two-body equations of motion were adapted to simplify the problem for a preliminary analysis. Monte Carlo simulations were performed for the statistical analysis to analyze diverse uncertainties that might arise at the moment when the maneuver is executed. As a result, three major requirements were analyzed and estimated for the early design phase. First, the minimum requirements were estimated for the burn performance to be captured around the moon. Second, the requirements for orbit, attitude, and maneuver burn performances were simultaneously estimated and analyzed to maintain the $1^{st}$ elliptical orbit achieved around the moon within the specified orbital period. Finally, the dispersion requirements on the B-plane aiming at target points to meet the target insertion goal were analyzed and can be utilized as reference target guidelines for a mid-course correction (MCC) maneuver during the transfer. More detailed system requirements for the KPLO mission, particularly for the spacecraft bus itself and for the flight dynamics subsystem at the ground control center, are expected to be prepared and established based on the current results, including a contingency trajectory design plan.

• 한국항공우주학회지
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• 제50권5호
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• pp.325-332
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• 2022

우주탐사 임무를 수행하기 위해서는 탐사선에 수직이착륙 기능이 필수적으로 탑재되어야 한다. 수직이착륙을 위해서는 탐사선의 엔진이 적절한 추력제어 정확도와 짧은 응답시간을 가져야 한다. 하이브리드 로켓은 이러한 조건을 만족할 수 있는 높은 수준의 추력제어 능력을 갖고 있다. 이 연구는 개발한 하이브리드 로켓 엔진의 추력제어 성능이 수직이착륙에 적절한지 검증하는 것을 목적으로 하고 있다. 이를 위해 가압장치 없이 공급압력이 감소하는 산화제 공급시스템을 적용한 엔진을 사용하여 약 10초 내외의 임무를 수행하고자 하였고, 공급압력 감소가 추력제어 정확도와 응답시간에 미치는 영향을 확인하였다. 실험결과에 의하면 적절한 감소율과 초기 압력 수준이 추력제어 정확도와 응답시간에 중요한 영향을 미치는 인자로 확인되었으며 고도제어 시뮬레이션을 통해 추력제어 성능을 검증했다.

• Wind and Structures
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• 제38권2호
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• pp.129-146
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• 2024

Aiming at the problem of non-stationary wind field simulation of downbursts, a non-stationary down-burst generation system was designed by adding a nozzle and program control valve to the inlet of the original wall jet model. The computational fluid dynamics (CFD) method was used to simulate the downburst. Firstly, the two-dimensional (2D) model was used to study the outflow situation, and the database of working conditions was formed. Then the combined superposition of working conditions was carried out to simulate the full-scale measured downburst. The three-dimensional (3D) large eddy simulation (LES) was used for further verification based on this superposition condition. Finally, the wind tunnel test is used to further verify. The results show that after the valve is opened, the wind ve-locity at low altitude increases rapidly, then stays stable, and the wind velocity at each point fluctuates. The velocity of the 2D model matches the wind velocity trend of the measured downburst well. The 3D model matches the measured downburst flow in terms of wind velocity and pulsation characteris-tics. The time-varying mean wind velocity of the wind tunnel test is in better agreement with the meas-ured time-varying mean wind velocity of the downburst. The power spectrum of fluctuating wind ve-locity at different vertical heights for the test condition also agrees well with the von Karman spectrum, and conforms to the "-5/3" law. The vertical profile of the maximum time-varying average wind veloci-ty obtained from the test shows the basic characteristics of the typical wind profile of the downburst. The effectiveness of the downburst generation system is verified.