• 한국군사과학기술학회지
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• 제16권1호
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• pp.74-80
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• 2013

In this paper, we have proposed a vapor cycle refrigeration system as a cooling system to provide cooling air to the aircraft external reconnaissance stores. In the proposed vapor cycle system, receiver which prevents refrigerant from subcooling was eliminated and thermal expansion valve was replaced with electronic expansion valve. The vapor cycle refrigeration system is aimed to provide cooling air to the reconnaissance stores which is added to the aircraft in the form of external store. The wide temperature range of ambient air from the flight conditions can decrease the cooling performance and can make the refrigeration system unstable in low ambient temperature. Performance characteristics of the vapor cycle refrigeration system has been experimented under air conditions which is derived from the flight envelope. From the experiments, the vapor cycle refrigeration system has been proved to provide enough cooling air to the reconnaissance equipment and to be stable under all the flight conditions.

• IEIE Transactions on Smart Processing and Computing
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• 제6권3호
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• pp.175-182
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• 2017

In this paper, we present a multi-depth generation method using a time-of-flight (ToF) fusion camera system. Multi-view color cameras in the parallel type and ToF depth sensors are used for 3D scene capturing. Although each ToF depth sensor can measure the depth information of the scene in real-time, it has several problems to overcome. Therefore, after we capture low-resolution depth images by ToF depth sensors, we perform a post-processing to solve the problems. Then, the depth information of the depth sensor is warped to color image positions and used as initial disparity values. In addition, the warped depth data is used to generate a depth-discontinuity map for efficient stereo matching. By applying the stereo matching using belief propagation with the depth-discontinuity map and the initial disparity information, we have obtained more accurate and stable multi-view disparity maps in reduced time.

• 로봇학회논문지
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• 제13권3호
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• pp.198-204
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• 2018

Quadrotor with limited flight time due to battery level can have the extended mission life by applying energy harvesting technology. Bio-inspiration from the birds' locomotion of flight and perch-and-stare can make energy consumption efficient, and energy harvesting technology can generate energy. In order to charge the battery with solar power, the drones are required to be in a position without shade. In the mountainous terrain, a novel mechanism is required in order to be located stably at the top of the tree or the inclined rock. In this study, we propose an analysis of the origami structure and the concept design of the perching mechanism with two stable equilibrium states. The origami structure composed of compliant material can be applied to the perching mechanism that can be locked passively. Moreover, the experimental results of the trajectory and perching test are discussed.

• 한국전자통신학회논문지
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• 제11권8호
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• pp.767-772
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• 2016

본 논문은 무인 비행체에 설치되어 VR 360도 영상을 촬영하기 위한 카메라 짐벌 시스템에 관한 것으로서, 특히 자이로 기술을 이용하여 무인 비행체가 어느 방향으로 회전되더라도 카메라의 위치가 고정되어 영상의 흔들림이 최소화되도록 하였다. 이를 통해 안정적인 VR 360도 전방위 촬영이 가능한 무인 비행체용 카메라 짐벌 시스템을 개발하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.344-348
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• 1992

This paper describes a procedure to design a hovering flight controller for a model helicopter using LQG theory. Parameters of the model helicopter in hover are obtained using direct measurements and calculations proposed by other research. A feedback co is by using digital LQG theory. First, a full state feedback controller is designed to the discretized system taking desirable transient response and other assumptions into account. Then a full-state estimator is designed and revised until desirable response is obtained while global stability is maintained. Performance of the controller is tested by computer simulations. Experiments have been performed using a 3-degree-of-freedom gimbal that holds the model helicopter, and the controller exhibited stable hover capability.

• 대한전자공학회논문지
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• 제24권4호
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• pp.559-567
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• 1987

In this paper, the real time simulation of continuous dynamic system was performed by general integration algorithms using multiprocessor. For the stable simulation, the relation between stability of integration method and integration step-size was investigated from the stability graph. As a typical illustration, the real-time digital simulation and the real-time hard-ware-in-the-loop simulation of flight control system were performed and reviewed. Moreover through the real-time simulation, the design verification and performace test of flight control system could be evaluated. The computer used for simulation is AD10, which is a very high-speed special-purpose computer designed specifically for a time-critical simulation of large and complex models of dynamic systems. The simulation validity is demonstrated by comparing hardware simulation results with software simulation results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.359-362
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• 2010

155mm 탄약에 사용되는 항력감소제는 다년간의 생산을 통해 안정적인 성능 및 품질 신뢰도를 확보하여 왔다. 이러한 기반 하에 비행시험 평가 대체기법의 타당성에 대한 연구를 수행하였으며 이를 통해 품질 안정성에 대한 확인뿐 아니라 비용감소, 시험 적체 해소 및 전력화 지연 방지 등의 대내외적인 효과를 얻을 수 있을 것으로 기대된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.779-783
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• 2004

First this paper introduces an advanced FADEC (Full Authority Digital Electric Control) for current and future jet engines.It is designed to realize not only stable thrust control, but also performance improvement, reliability enhancement, service life extension, etc. It can be built by using current micro-processor with high computational power and there exists no difficulties but reliability problem of the micro- processor. Next, the simulation results of SFC minimization control are shown. The target engine is a supersonic, low-bypass ratio, 2-spool, combined cycle turbofan, designated as HYPR90T, which consists of a turbo engine for under Mach 3 flight and a ram engine for over Mach 3 flight. he results can then be used for performance optimization of the engine, which plays important role in the advanced FADEC.

• 로봇학회논문지
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• 제16권3호
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• pp.216-222
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• 2021

Recently, various robots are being used for the purpose of structural inspection or safety diagnosis, and their needs are also rising rapidly. Among the structural inspection using robots, a lot of researches has recently been conducted on inspection of various facilities and structures using an unmanned aerial vehicle (UAV). However, since GNSS (Global Navigation Satellite System) signals cannot be received in an environment near or below structures, the operation of UAVs has been done manually. For a stable autonomous flight without GNSS signals, additional technologies are required. This paper proposes the autonomous flight system for structural inspection consisting of simultaneous localization and mapping (SLAM), path planning, and controls. The experiments were conducted on an actual large bridge to verify the feasibility of the system, and especially the performance of the proposed SLAM algorithm was compared through comparative analysis with the state-of-the-art algorithms.

• 한국운동역학회지
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• 제17권1호
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• pp.165-174
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• 2007

The subject of this study was male apparatus gymnastics athlete who had scored high points doing basket with 1/2 turn on parallel bars. Then 3D motion analysis were used to calculate & analyse kinematic variables of Basket with 1/2 turn to Handstand. 1. The total average time spent for Basket with 1/2 turn took $2.16{\pm}.08sec$, at the downward upward phase took $.58{\pm}0.00sec$, $.23{\pm}.00sec$, at flight phase took $.28{\pm}.01sec$, at connected area phase took $.72{\pm}0.21sec$, at rotation area phase took $.35{\pm}.14sec$. To have a successful performance, there should be faster speed and velocity to rotate at the downward upward phase, then the upward velocity and height must be used adequately. Moreover, the speed must be faster at the flight connect phase to stabilize Center of Mass(CM) for the body, and must secure more time at the rotation area to have more stable performance. 2. After handstand on parallel bars while moving CM to right hand side, and It must be performed with big and magnificent performance with putting both hand's center to far away from the parallel bars. 3. Furthermore, CM must be moved fast from downwards to right hand side, and CM must be moved fast in vertical movement at upward and flight phase to avoid CM from moving back and forth, and left and right. 4. At downwards, the subject must rotate as bis as possible using hip-joint as wide as possible and at upwards, must put his body to vertical to have stable performance. While rotating or turning, it is better to do with bigger shoulder angle and have to make sure that trunk angle must be not scattered. To perform better and more positive in basket with 1/2 turn on parallel bars, the centrifugal force must be used big and fast at downward, and at upward and flight phase, downward movement must change to vertical movement as soon as possible while turning movement must happen at handstand position. Time spent must be shorten at connected area to stabilize CM and turning must be natural as possible while securing the necessary time of movement to well-balanced. Also, the body must be vertically closed from the ground.