• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.448-451
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• 2008

KARI is developing a satellite launch vehicle that is called KSLV(Korea Space Launch Vehicle)-I. During the flight, launch vehicles are exposed to aerodynamic heating conditions while flying at high Mach numbers in the atmosphere. KARI constructed Aerodynamic Thermal Simulation Facility to simulate aerodynamic heating on the ground. ATSF is a facility that can simulate given temperature profile using about 4,000 halogen heaters on fairing model. Aerodynamic heating profile is got from result of thermal analysis using MINIVER, Thermal Desktop, and SINDA/FLUINT. Aerodynamic heating test of fairing of KSLV-I was done using engineering model of payload fairing and Aerodynamic Thermal Simulation Facility. It was found that thermal analytic results show good agreement with aerodynamic heating test results within 6$^{\circ}$C at fairing inner surface. Also it was confirmed that maximum temperature of fairing nose-cone inner surface during flight is lower than allowable temperature limit.

• 한국군사과학기술학회지
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• 제16권6호
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• pp.739-744
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• 2013

In this paper, we propose a method of generating pitch commands for consistent initial trajectories irrelevant to flight conditions in the initial boosting phase of a thrust-vector-controlled vehicle. After shape assumption of the pitch command profile, parameters of the profile are determined in real time in order for the summit height of the trajectory to be a desired value by deriving the summit height considering thrust performance, gravity, and other flight conditions. Computer simulation results demonstrate good performance of the proposed method.

• 한국분말재료학회지
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• 제1권1호
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• pp.85-94
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• 1994

In order to predict droplet velocity and temperature profiles and fractional solidification with flight distance during spray forming, the Newtonian heat transfer formulation has been coupled with the classical heterogeneous nucleation and the specific solidification process. It has been demonstrated that the thermal profile of the droplet in flight is significantly affected by process parameters such as droplet size, initial gas velocity, undercooling. As the droplet size and/or the initial gas velocity increase, the onset and completion of solidification are shifted to greater flight distances and the solidification process also extends over a wider range of flight distances. The amounts of solid fractions formed during recoalescence, segregated solidification and eutectic solidification are insensitive to droplet size and initial gas velocity whereas those are strongly affected by the degree of undercooling. There are good linear relations between the undercooling and the corresponding solid fractions generated during recoalesced, segregated and eutectic stages.

• 천문학회보
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• 제44권2호
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• pp.58.1-58.1
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• 2019

We have developed Ground Software (GSW) of BITSE. The ground software includes mission operation software, data visualization software and data processing software. Mission operation software is implemented using COSMOS. COSMOS is a command and control system providing commanding, scripting and data visualization capabilities for embedded systems. Mission operation software send commands to flight software and control coronagraph. It displays every telemetry packets and provides realtime graphing of telemetry data. Data visualization software is used to display and analyze science image data in real time. It is graphical user interface (GUI) and has various functions such as directory listing, image display, and intensity profile. The data visualization software shows also image information which is FITS header, pixel resolution, and histogram. It helps users to confirm alignment and exposure time during the mission. Data processing software creates 4-channel polarization data from raw data.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.391-400
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• 2016

In satellite operations, stable maneuvering of a satellite's onboard antenna to prevent undesirable vibrations to the satellite body is required for high-quality high-resolution images. For this reason, the onboard antenna's angular rate is typically minimized while still satisfying the system requirement that limits the speed of the onboard antenna. In this study, a simple yet effective method, called the ground station searching method, is proposed to reduce the angular rate of a satellite's onboard antenna. The performance of the proposed method is tested using real flight data from the KOMPSAT-3 satellite. Approximately 83% of arbitrarily selected real flight scenarios from 66 test cases show reductions in the onboard antenna's azimuth angular rates. Additionally, reliable solutions were consistently obtained within a reasonably acceptable computation time while generating an onboard antenna tracking profile. The obtained results indicate that the proposed method can be used in real satellite operations and can reduce the operational loads on a ground operator. Although the current work only considers the KOMPSAT-3 satellite as a test case, the proposed method can be easily modified and applied to other satellites that have similar operational characteristics.

• 한국정밀공학회지
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• 제17권6호
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• pp.111-118
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• 2000

The design of reference trajectory with respect to drag acceleration is necessary to decelerate from hypersonic speed safely after atmosphere re-entry of space vehicle. The re-entry guidance design involves trajectory optimization, generation of a reference drag acceleration profile with the satisfaction of 6 trajectory constraints during the re-entry flight. This reference drag acceleration profile can be considered as the reference trajectory. The cost function is composed of the accumulated total heating on vehicle due to the reduction of weight. And a regularization is needed to prevent optimal drag profile from varying too fast and achieve realized trajectory. This paper shows the relations between velocity, drag acceleration and altitude in drag acceleration profile, and how to determine the reference trajectory.

• 한국항공운항학회지
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• 제30권3호
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• pp.109-116
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• 2022

A modular platform development technique was proposed to minimize development cost and development period by utilizing the already developed unmanned Aerial target AVT, which has been operated and verified for many years. New Mission Profile was designed and structural analysis was performed through finite element analysis (FEA) by analyzing mission requirements for visual short-range, non-visible mid-range, and long-range targets. The targets are used for guided missile anti-aircraft training. In addition, avionics systems including flight control computers for autonomous flights were developed to verify their conformance by performing launcher take-off tests with rapid acceleration changes and autonomous flight tests at a maximum speed of 300km per hour.

• International Journal of Aeronautical and Space Sciences
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• 제14권3호
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• pp.264-271
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• 2013

A method of multiple transport-aircraft mission modeling is proposed in order to improve the efficiency of evaluating and optimizing pre-mission plans. To deal with the challenge of multiple transport-aircraft missions, the object-oriented modeling method is utilized. The elements of the mission are decomposed into objects and businesses, And the major mission objects and their important properties are summarized. A complex mission can be broken down into basic business modules such as the ground section and flight section. The business models of loading and fueling services in the ground section are described. The business model of the flight section is composed of an air route and flight profile with the flight equation and the fuel consumption model. The logical relationship of objects and business modules is introduced. The architecture of the simulation system, which includes a database, computation module, graphical user interface (GUI) module, and a result analysis module, is established. A sample case that includes two different plans is provided to verify the model's ability to achieve multi-aircraft composite mission simulation.

• 한국정보통신학회논문지
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• 제5권6호
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• pp.1163-1168
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• 2001

거리 계측 시스템은 물체까지의 거리를 삼차원 좌표계에서 측정하는 장치이다. 군용 장비나 건설, 항해, 검사 조립, 로봇 비전 등에 널리 사용되는 무접촉식 원격 거리 계측(ranging) 시스템은 자동화 응용에 매우 중요하다. 계측 방식은 active와 passive방식으로 구분되는데, active방식은 laser나 microwave, 초음파 등의 time of flight를 이용하거나 레이저 조사(illumination)에 대한 카메라 영상을 해석하는 등의 다양한 방식이 있으나 장치가 복잡하며, passive 방식은 stereo camera의 양안영상을 이용하거나 focus특성을 이용하는 방식 등이 있으나 대부분 연산시간이 많이 요구된다. 본 연구에서는 수동식 스테레오 카메라에서 양안시차를 산출하여 triangulation으로 목표전의 거리를 측정하는 방식에서, 연산 시간이 많이 소요되는 과정을 고속으로 처리하는 새로운 방식을 제안하였다. 즉, 목표점에서의 양안 edge 영상을 구하고, 이 영상의 projection profile을 cross correlation하여, 시차를 고속으로 산출해 거리를 구하는 알고리즘을 제안하였으며, 이 방식의 효율성을 실험 결과를 통하여 보였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.47-52
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• 2004

극초음속 스크램제트 흡입구의 설계는 다양한 공기열역학적인 현상을 수반한다. 이러한 현상은 무딘 앞전효과, 경계층 발달 문제, 천이, 점성/비점성 결합, 충격파 상호작용, 충격파 경계층 상호작용 및 유동 형상 등을 포함한다. 한정된 마하수와 고도 영역 내에서 운용되기 위해 설계되는 흡입구에서는 이러한 현상들 중 몇 가지 현상에 대한 이해가 요구된다. 본 연구에서는 HyShot 비행시험에서 발생할 수 있는 고도와 받음각 극단에서의 흡입구 성능을 연구하기 위해 몇 가지 중요한 유동 현상(점성 현상, 경계층 박리, 연소기 입구 유동 형상)들이 논의 될 것이다.