• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.2
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• pp.152-160
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• 2008

In the present paper, a transonic mixed-flow compressor that has relatively lower frontal area than that of centrifugal compressors is discussed, and aerodynamic design as well as performance prediction are performed. Main design constraints are compressor exit Mach number of 0.3 and flow angle of 30degrees at the design point, and maximum overall compressor diameter of 177mm, that is 7.0inch. The mass flow rate of design point and pressure ratio are 1.05kg/s and 5.2:1, respectively. The aerodynamic design results show that the transonic compressor designed with forward-swept inducer and curved diffuser can have the target performance with efficiency of 75% within the given constraints. And the compressor exit flow characteristics are discussed here.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.57-60
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• 2007

국방 연구개발은 사용군의 요구사항을 만족시키는 무기체계를 최단 기간, 최소 비용 및 고품질로 개발하고자 노력하고 있으며, 통합 무기체계 데이터베이스 전산 환경 하에서 체계공학 및 동시공학을 체계적으로 구현하기 위한 연구개발 프로세스 및 도구들이 개발되고 있다. 항공 무기체계 분야에서 본 논문의 연구개발 과정에서 생성되는 기술 자료를 효율적으로 관리하기 위한 웹기반 체계운영관리시스템을 개발 및 운용하고 있으며, 기존 항공 무기체계 연구개발 사업에 적용하여 그 효율성을 입증 및 검증하였다. 이에 본 논문에서는 통합 무기체계 데이터베이스 기반으로 향후 개발 예정인 보라매 사업, 무인항공기 및 무인전투기에 적용 가능한 통합 연구개발 프레임웍(Framework) 및 체계운영관리시스템의 발전 방안에 대해서 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1574-1579
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• 2016

This paper presents a self-powered sensor-node scheme using a RF wireless power harvesting techniques for improve drone time of flight. Sensor-node that is proposed is turned when two conditions satisfy: The one is input RF ID data from master-node should be same with sensor-node's ID, and the other one is RF wireless power harvesting system is turned on by hysteresis switch. In this paper, master-node's output is 26 dBm at 263 MHz. Maximum RF to DC power conversion efficiency is about 55% at 4-6 dBm input power condition (2 meter from master-node). The maximum RF wireless power harvesting range is about 13 meter form master-node. And power consumption of the sensor-node's load elements such as transmitter, MCU and temperature sensors is approximately average 15 mA at 5.0 V for 10 msec.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.127-137
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• 2018

Recently, UAVs and Drones have been used for various applications. In particular, in the field of surveying, there are studies on the technology for monitoring the terrain based on the high resolution image data obtained by using the UAV-equipped digital camera or various sensors, or for generating high resolution orthoimage, DSM, and DEM. In this study, we analyzed the accuracy of GCP(Ground control point) matching using UAV and VRS-GPS. First, we used VRS-GPS to pre-empt the ground reference point, and then imaged at a base altitude of 150m using UAV. To obtain DSM and orthographic images of 646 images, RMSE was analyzed using pix4d mapper version As a result, even if the number of GCP matches is more than five, the error range of the national basic map(scale : 1/5,000) production work regulations is observed, and it is judged that the digital map revision and gauging work can be utilized sufficiently.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.11-19
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• 2016

Recently, global companies are developing the automobile technologies, converged with state-of-the-art IT technologies for the commercialization of autonomous vehicles. These autonomous vehicles are required the accurate lane information to enhance its reliability by controlling the vehicles safely. Hence, the study planned to examine possibilities of applying UAV photogrammetry of high-resolution images, obtained from the low altitudes. The high-resolution DSM and the ortho-images were generated from the GSD 7cm-level digital images that were obtained and based on the generated data, when the positions information of the roads including the lanes were extracted. In fact, the RMSE of verifying the extracted data was shown to be about 15cm. Through the results from the study, it could be concluded that the low alititude UAV photogrammetry can be applied for generating and updating a high-accuracy map of road areas.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1135-1147
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• 2021

In order to geometrically correct high-resolution satellite imagery, the sensor modeling process that restores the geometric relationship between the satellite sensor and the ground surface at the image acquisition time is required. In general, high-resolution satellites provide RPC (Rational Polynomial Coefficient) information, but the vendor-provided RPC includes geometric distortion caused by the position and orientation of the satellite sensor. GCP (Ground Control Point) is generally used to correct the RPC errors. The representative method of acquiring GCP is field survey to obtain accurate ground coordinates. However, it is difficult to find the GCP in the satellite image due to the quality of the image, land cover change, relief displacement, etc. By using image maps acquired from various sensors as reference data, it is possible to automate the collection of GCP through the image matching algorithm. In this study, the RPC of KOMPSAT-3A satellite image was corrected through the extracted matching point using the UAV (Unmanned Aerial Vehichle) imagery. We propose a pre-porocessing method for the extraction of matching points between the UAV imagery and KOMPSAT-3A satellite image. To this end, the characteristics of matching points extracted by independently applying the SURF (Speeded-Up Robust Features) and the phase correlation, which are representative feature-based matching method and area-based matching method, respectively, were compared. The RPC adjustment parameters were calculated using the matching points extracted through each algorithm. In order to verify the performance and usability of the proposed method, it was compared with the GCP-based RPC correction result. The GCP-based method showed an improvement of correction accuracy by 2.14 pixels for the sample and 5.43 pixelsfor the line compared to the vendor-provided RPC. In the proposed method using SURF and phase correlation methods, the accuracy of sample was improved by 0.83 pixels and 1.49 pixels, and that of line wasimproved by 4.81 pixels and 5.19 pixels, respectively, compared to the vendor-provided RPC. Through the experimental results, the proposed method using the UAV imagery presented the possibility as an alternative to the GCP-based method for the RPC correction.

• Current Industrial and Technological Trends in Aerospace
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• v.5 no.2
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• pp.98-106
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• 2007

한 나라의 우주개발은 막대한 예산과 많은 시간이 소요되기 때문에 정부주도로 연구개발사업을 시작하는 것이 대체적인 선례이다. 하지만 때로는 우주개발을 지역사회나 주변 국가들과의 상황에 따라 생존을 위한 방편으로도 활용될 수 있다. 이러한 우려를 불식시키거나 완화하자는 차원에서 국제사회가 다자간 협의체인 미사일기술통제체제(MTCR, Missile Technology Control Regime)을 1987년부터 시작하여 매년 총회 및 회기간 회의를 통하여 국제사회에서 대량파괴무기의 운반체로 미사일이나 무인항공기 등과 관련된 시스템 및 부품 등의 기술이전 등에 관하여 규제를 하고 있는 것이다. 최근 국제사회에서 핵 프로그램 및 미사일 문제로 논쟁의 핵심이 되고 있는 이란에 대하여 우주개발과 미사일기술통제체제의 규제 등의 관점에서 본 논문을 검토하고자 한다.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.217-223
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• 2015

This paper describes the design and implementation of a network system for UAV for multiple clients that enables long-range operation based on a commercial mobile network. A prototype data modem is developed with a commercial embedded M2M module in order to provide an access to the mobile network. A central server with a database is constructed to record all of real-time flight and video data and communicate with a ground control system. A GCS is developed for the central control, the single UAV and the smart phone version to be used for different purposes. Performance tests were progressed for data delay, video frame rate and state of clients. Flight tests were also performed to verify the reliability of the modem with respect to altitude.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.114-122
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• 2022

This paper explores three-dimensional unsteady computational fluid dynamic (CFD) analyses with an overset grid technique to analyse the wake effect created by a rotating propeller on a hand-launched unmanned aerial vehicle (UAV). Additionally, the influence of actual aileron deflection on the equilibrium condition of the rolling moment is examined in various hand-launched take-off conditions. The results of this study demonstrate the importance of initial aileron deflection in increasing the initial rolling stability during the hand-launched take-off process. Furthermore, an aerodynamic database is constructed to rapidly predict the aileron set values required for different take-off speeds and angle-of-attacks.

• Information and Communications Magazine
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• v.33 no.2
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• pp.100-106
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• 2016

전 세계적으로 드론에 대한 관심이 급격히 커지면서 많은 국가에서 드론을 미래 전략산업의 하나로 주목하고 있으며 드론 관련 기술에 대한 연구개발과 활용을 위해 많은 노력을 하고 있다. 기술개발 투자와 규제해소를 위한 법 정비 등 국내 여건이 미비한 상황에서 군사용 무인항공기 강국인 미국은 국가공역체계 안에서 드론 법제화 정립을 진행하고 있으며, 중국 등 몇몇 국가의 기업들은 초소형 민간 드론 시장에서 강력한 경쟁력을 보이고 있다. 드론 기술의 발전과 시장이 확대되기 위해서는 공공드론의 역할이 매우 중요하다. 기술적 법적 제약이 적지 않은 환경에서 공공분야의 드론 활용은 기술 개발과 수요증대를 동시에 자극 할 수 있는 촉매제가 될 수 있기 때문이다. 본 고에서는 미래 수요 증가의 한 축으로 기대되는 드론의 공공임무 활용부문에 대한 분석과 나아갈 방향을 제시한다.