• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.279-283
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• 2006

The GPS receiver developed by KARI for the satellite launch vehicle should operate under severe dynamic environments such as high acceleration and jerk. Several terrestrial tests including the outdoor centrifuge test are planed in order to verify performances of the GPS receiver before flight. This paper deals with preliminary test results of the GPS receiver using a GPS signal generator before the centrifuge test that is a performance test of the GPS receiver using live GPS satellite signals. Test methods of the GPS receiver for the satellite launch vehicle under high centripetal acceleration and jerk utilizing a GPS signal generator are described. The simulation results are also analyzed in this paper.

• 한국항공우주학회지
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• 제45권12호
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• pp.1069-1075
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• 2017

최근 우주 기술이 발달함에 따라 전 세계적으로 위성 시장, 특히 소형 위성 시장이 크게 성장하고 있다. 이러한 위성 시장의 성장세 속에서 발사체 시장 역시 성장세를 보이고 있으며 이에 따라 저비용 발사에 대한 수요가 점점 증가하고 있다. 저비용 발사를 위한 방안에는 저비용 추진제를 사용하는 엔진 개발, 제품 생산 및 운송비용 절감 등 다양한 방법이 존재하지만, 발사 비용을 가장 크게 줄이는 방법은 바로 사용한 발사체를 다시 사용하는 것이다. 재사용 발사체의 시작은 유인 우주선으로 유명한 미국의 Space Shuttle이라 할 수 있다. 하지만 Space Shuttle의 경우 재사용이라고 불리기는 하지만 재사용 할 수 있는 부분이 한정되어 있고, 발사 효율이 떨어져 재사용 발사체 임에도 불구하고 상당히 고비용이었다. 최근에는 미국의 SpaceX와 Blue Origin을 중심으로 상업적 목적의 재사용 발사체가 개발 되고 있고 재착륙 시험에 성공하였다. 뿐만 아니라, SpaceX의 경우 이전 재착륙을 성공한 1단 발사체를 정비하여 다시 발사하는데 까지 성공하기도 하였다. 이러한 추세에 따라 유럽, 인도와 같은 국가에서도 현재 재사용 발사체 연구에 심혈을 기울이고 있다. 그리고 Blue Origin을 포함한 미국의 Virgin Galactic, XCOR 등은 민간 유인 우주여행과 같은 재사용 기술을 이용한 상품화도 시도하고 있다. 재사용 기술이 확립되면 세계 발사체 시장의 판도가 바뀔 수 있기에 재사용 기술 동향의 정기적인 확인은 필수적이라 할 수 있다.

• 항공우주기술
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• 제10권2호
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• pp.94-100
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• 2011

본 논문에서는 고성능 저궤도 지구관측위성의 예비연성하중 해석결과에 대하여 평가한다. 연성하중해석을 수행하기 위하여 위성체 모델을 Craig-Bampton 모델로 축약한 후 발사체 개발업체로 제공하였다. 제공된 Craig-Bampton 모델은 인공위성의 질량행렬, 강성행렬, 가속도변환행렬 및 변위변환행렬이다. 발사체 개발업체에서는 위성체 Craig-Bampton 모델과 발사체 모델을 결합하여 연성하중해석을 수행한 후 그 결과를 제공하였다. 제공받은 연성하중해석 결과를 바탕으로 발사시 위성체가 구조적으로 이상이 없는지를 평가하였다. 평가결과 위성체는 발사하중하에서 안전함을 확인할 수 있었다.

• 제어로봇시스템학회논문지
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• 제7권2호
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• pp.173-182
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• 2001

Ascent trajectory optimization and optimal explicit guidance problems for a satellite launch vehicle in a 2-dimensional pitch plane are studied. The trajectory optimization problem with boundary conditions is formulated as a nonlinear programming problem by parameterizing the pitch attitude control variable, and is solved by using the SQP algorithm. The flight constraints such as gravity-turn are imposed. An optimal explicit guidance algorithm in the exoatmospheric phase is also presented, the guidance algorithm provides steering command and time-to-go value directly using the current states of the vehicle and the desired orbit insertion conditions. To verify the optimality and accuracy of the algorithm simulations are performed.

• Advances in aircraft and spacecraft science
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• 제7권4호
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• pp.371-385
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• 2020

A forward-facing aerospike attached to a payload fairing of a satellite launch vehicle significantly alters its flowfield and decreases the aerodynamic drag in transonic and low supersonic speeds. The present payload fairing is an axisymmetric configuration and consists of a blunt-nosed body along with a conical section, payload shroud, boat tail and followed by a booster. The main purpose of the present numerical simulations is to evaluate flowfield and assess the performance of aerodynamic drag coefficient with and without aerospike attached to a payload fairing of a typical satellite launch vehicle in freestream Mach number range 0.8 ≤ M_∞ ≤ 3.0 and freestream Reynolds number range 33.35 × 10⁶/m ≤ Re_∞ ≤ 46.75 × 10⁶/m whichincludes the maximum aerodynamic drag and maximum dynamic conditions during ascent flight trajectory of the satellite launch vehicle. A numerical simulation has been carried out to solve time-dependent compressible turbulent axisymmetric Reynolds-averaged Navier-Stokes equations. The closure of the system of equations is achieved using the Baldwin-Lomax turbulence model. The aerodynamic drag reduction mechanism is analysed employing numerical results such as velocity vector plots, density and Mach contours in conjunction with the experimental flow visualization pictures. The variations of wall pressure coefficient over the payload fairing with and without aerospike are exhibiting different kind of flowfield characteristics in the transonic and low supersonic speeds. The numerically computed results are compared with schlieren pictures, oil flow patterns and measured wall pressure distributions and exhibit good agreement between them.

• 항공우주시스템공학회지
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• 제1권3호
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• pp.37-42
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• 2007

The flight safety system for the satellite launch vehicles is required in order to minimize the risk due to launch vehicle failure. For prompt and reliable decision of flight termination, the flight safety system usually uses multiple sensors to estimate launch vehicle's flight trajectory. In that case, multiple types of observed tracking data makes it difficult to identify the flight termination condition. Therefore, a fusion tracking filter handling the multiple tracking data is necessary for the flight safety system. This research developed a simulation software for generating multiple types of launch vehicle tracking data, and then processed the data with fusion filters.

• 항공우주기술
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• 제8권2호
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• pp.33-40
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• 2009

본 논문에서 [1MHz-47MHz]의 주파수 범위에서의 통신해양기상위성과 정지궤도 발사체와의 예비적인 EMC 해석 과정을 기술한다. 정지궤도용 발사체 최대 복사 방출 한계치와 위성의 최대 복사 감응 한계치와 비교한다. 전자파 호환이 되지 않는 발사체로는 land launch와 소유즈가 있다. 만약에 이 발사체가 선정된다면 위성체 레벨에서 전자파 시험을 통하여 검증하여야 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.358-362
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• 2006

Pyro-shock generally refers to the severe mechanical transients caused by the detonation of an ordnance device on a structure. Such device on a structure, including linear explosive, and point explosive are widely used to accomplish in-flight separation of structural elements on aerospace vehicle. And they are a significant cause of launch vehicle failures. The launch vehicle being developed in Korea also uses the explosive for separation events. In this paper, the isolator equipped to small satellite launch vehicle made of PTFE(Teflon) is developed to reduce the separation shock. The test to measure dynamic stiffness of PTFE isolator is performed. This test enables us to find the frequency range of PTFE isolator. And,, pyre-shock test using explosive to evaluate the performance of PTFE isolator is executed. from this study, the isolator conformed to frequency range and load requirement is developed using PTFE instead of rubber.

• 항공우주시스템공학회지
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• 제1권3호
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• pp.1-6
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• 2007

The COMS(Communication, Ocean & Meteorological Satellite)is the geostationary satellite which will be performing three main objectives such as meteorological service, ocean monitoring and Ka-band satellite communications. This paper presents the analysis of the electromagnetic radiated compatibility between COMS satellite and the ARIANE 5 launch vehicle. As a conclusion, a good level of confidence can be given at present time to demonstrate the compatibility between the spacecraft and the launcher, and vice versa. No threat has been identified regarding the other units powered during launch mode.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.193-196
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• 2006

Vibration overtests have been common problems in aerospace industry. A test item can be overtested at its resonances when it is excited by the traditional spectrum enveloping peaks in the field acceleration spectrum. This paper introduces the method of modifying the excitation specification to alleviate the overtesting problem. A vibration analysis was performed to estimate interface forces and acceleration responses. A finite element model that was verified by an extensive modal test enabled us to shape the acceleration input accurately The produced notched input will be used in the sinusoidal vibration test of the small satellite launch vehicle.