• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.27-30
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• 2005

Hanwha Corporation succeeded in domestic development of thruster heat shield for KOMPSAT-2 propulsion subsystem partly. Thruster heat shield, one of the main components of DTM, is designed to prevent the critical radiative heat exchange between thruster and satellite during firing. To overcome the manufacturing difficulties, an electro-forming process is preferred to classical welding process. In this case, an inner diameter of a new shield will be decreased a little due to the change of manufacturing process. The interference problem between thruster nozzle and heat shield was investigated through structural analysis by KARI. Hanwha manufactured heat shield based on the analysis results. In this paper, full development process is described for design, analysis, manufacturing of heat shield.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1071-1078
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• 2015

Numerical computations were performed to investigate the effects of pintle stroke, altitude, and bore on the performance of an external pintle thruster. Results show that under-expansion flow occurs always, independent of pintle stroke. An external pintle thruster shows good performance in that it is capable of good amount of thrust control, while aerodynamic loads are increased due to shock waves on the pintle support. When altitude is increased to 20 km, the nozzle exit velocity, Mach number, thrust as well as aerodynamic loads are increased. Bore increases aerodynamic load 5.9%, and therefore pintle shape without bore is preferred for lower aerodynamic load of a pintle in order to actuate the pintle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.54-60
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• 2006

This paper discusses wheel offloading approaches of the COMS which has a single solar array system for the accommodation of the optical payloads. First of all, in an effort to reduce fuel consumption and reflect practical implementation point of view, thruster sets for wheel offloading are proposed based on numerical analyses taking into account the COMS configuration. In this analysis, it is assumed that the wheel offloading is conducted twice a day. Secondly, in order to evaluate the effectiveness of the proposed thruster sets, orbit simulations are conducted for several wheel offloading approaches and compared.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.1-12
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• 2019

A fundamental study on a gas injection variable thrust method for thrust throttling in a liquid rocket engine was conducted. The gas injection variable thrust has the advantage of not only being able to control the thrust with a simple structure but it also increases the atomization performance through the injection pressure drop that increases in direct proportion to the density reduction. In this study, spray characteristics such as spray instability, spray pattern, spray angle, and breakup length based on changes in the liquid mass flow rate and amount of injected gas were investigated using effervescent swirl injectors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.21-21
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• 1998

추력방향 제어시스템 설계에 있어서 가장 기본적으로 요구되는 Requirement는 Rocket Motor의 추력, 요구되는 최대 Side Force, Rocket Motor의 외경, System의 총 구동시간, 구동후의 분리여부 등이다. 이러한 Requirement를 만족하기 위해서는 Nozzle 출구의 분출가스 물성치로부터 초음속 유동해석을 통하여 Vane 주위의 속도, 온도, 압력 분포를 구하고, Vane의 받음각 변화에 대한 Aerodynamic Force와 Moment를 계산하고, Side Force를 만족하는 최대 받음각의 결정, Torque를 만족하는 감속기와 Motor의 선정 및 Housing 기본 형상을 설계하였다. 금번 개발에서는 지상 시험용으로서 안전 계수를 Flight Model보다 약간 높게 설계하였으며, 작동 완료 후 System이 Nozzle로부터 떨어져나가는 분리시스템은 포함하지 않았다.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.1-9
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• 2017

Numerical computations are performed to investigate the effect of pintle stroke on the performance of an internal pintle thruster. Results show that the thrust control ratio was less than 2% and the aerodynamic load ratio was 22% as the pintle stroke increased. The flow past the nozzle throat rapidly expanding because of the shape of the pintle, and a shock wave was generated. Particularly, at the pintle stroke distance of 4 and 5 mm, the shock wave hit the wall of the nozzle, results in peeling bubbles. Depending on the altitude, the thrust increased and the aerodynamic load decreased, but the difference was as small as 1.5%. In the presence of the bore, the reduction of the pintle tip area resulted in a decrease in aerodynamic load.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.50-57
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• 2014

A ground hot-firing test (HFT) was conducted to take out the optimal design configurations for the thrust chamber of 70 N-class liquid rocket engine under development. Monopropellant grade (purity: ${\geq}98.5%$) hydrazine was adopted as a propellant for the HFT, and three kinds of thrust chambers having characteristic lengths ($L^*$) of 2.79, 2.95, and 3.13 m were selected for their performance evaluation. It is revealed through the test and evaluation that the increase of the $L^*$ leads to a performance degradation in the test condition specified, and pulse response performance of the development model shows superior characteristics to commercialized hydrazine thrusters.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.164-170
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• 2007

In this paper, the development results of electromechanical TVC actuation system is described in the aspect of design, analysis, manufacturing and test. The kinds of prime power for TVC actuation system is classified by the variety of propulsion system of launch vehicle. The electric power by battery is the sole candidate for prime power of TVC actuation system at the view point of feasible domestic infra technologies for the present. The characteristic analysis study is performed between electromechanical and electrohydraulic actuation system with respect to power efficiency, performance and weight efficiency. The electromechanical actuation system has superiority of power and weight efficiency according to less opportunity of power conversion process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.9-9
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• 1998

다목적 실용위성의 궤도전이 및 위성체 자세제어를 위한 추진시스템의 설계요소에는 구조적 안전성, 우주환경에서의 열제어를 위한 회로 및 구성하드웨어 설계, 연료계통 맥압강하를 위한 장치설계 및 추력기 배기가스 영향을 고려한 형상설계 등이 있으며, 설계검증을 위해 부분해석이 수행된다. 또한 발사환경과 우주 궤도환경에서의 추진시스템 성능평가를 위한 연제어계 기능시험, 압력인증시험, 청정도시험 및 내부/외부 누설시험이 수행된다. 본 논문에서는 추진시스템 설계 및 조립공정에 대해 기술하였고, 시험분석을 통해 시스템의 설계 및 조립공정상의 신뢰성을 검증 분석하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.791-797
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• 2018

In this work, the high-altitude environment simulation study was carried out at an altitude of 65 km exceeding Mach number of 6 after the launch of Korean Space Launch Vehicle using a shock tunnel. To minimize the flow disturbance due to the strut support of test model as much as possible, a few different types of strut configurations were considered. Using the configuration with minimum disturbance, the high-altitude environment simulation experiment including a propulsion system with a single-plume, was conducted. From the thruster test through flow visualization, not only a shockwave pattern, but a general flow-field pattern from the mutual interaction between the exhaust plume and the free-stream undisturbed flow, was experimentally observed. The comparison with the computation fluid dynamic(CFD) results, showed a good agreement in the forebody whereas in the afterbody and the nozzle the disagreement was about ${\pm}7%$ due to unwanted shockwave formation emanated from the nozzle-exit.