• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1637-1642
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• 2004

Experimental and computational studies were performed to investigate the effectiveness of a thrust vectoring method using a counterflow concept. A shadowgraph method was used to visualize the supersonic jet expanded from a two-dimensional convergent-divergent nozzle and deflected by a now suction. The primary nozzle pressure and suction nozzle pressure ratios are varied between 3.0 and 5.0, and between 0.2 and 1.0 respectively. The present experimental and computational results showed that, for a given primary nozzle pressure ratio, a decrease in the suction nozzle pressure ratio produced an increased thrust vector angle, and during the change processes of the suction pressure, a hysteresis effect of the thrust vectoring was found through the wall pressure distributions.

• International Journal of Fluid Machinery and Systems
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• 제9권4호
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• pp.354-361
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• 2016

This study aims to identify aerodynamic characteristics of the ramp tab, a mechanical deflector, by conducting a non-combustive experiment using compressed air and supersonic flow test equipment. With the ramp tabs installed symmetrically and asymmetrically on the outlet of the supersonic nozzle, the structure of the flow field, the thrust spoilage, the thrust deviation angle, and the lift/drag coefficients were derived and analyzed. The results show that the asymmetrically-installed ramp tabs are advantageous relative to the symmetrically-installed tabs in terms of the performance of thrust vector control, thrust deviation angle, and lift coefficient.

• 한국추진공학회지
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• 제11권3호
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• pp.13-19
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• 2007

본 논문에서는 추진기관의 추력방향 성능 평가에 적용되는 다축시험대의 상호 간섭 최소화 설계 방안에 대해서 논하였다. 다축시험대의 변형 모델링으로 상호 간섭 크기를 이론적으로 예측하고 설계변수가 상호 간섭 크기에 미치는 영향을 평가하였다. 본 논문의 결과로부터 다축시험대 설치에 따른 정렬오차, 힘에 의한 시험대의 변형이 상호 간섭에 가장 큰 영향을 미치며 로드셀과 플렉셔의 물성 및 기하학적 형상에도 영향을 받는 것으로 분석되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.49-51
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• 1994

LIM has been developed for use in the industry, transportation, OA, FA because of the merits of direct drive and simple structure. The thrust control of LIM usually has been the average thrust control. However, vector control is required to control the instantaneous thrust force for an accurate positioning and speed control. To obtain dynamic vector control characteristics, it is important to make equivalent circuits which represent exactly LIM In this paper, asymmetrical d-q equivalent circuits is built [1] and vector control characteristics is calculated by simulation using these circuits.

• 한국항공운항학회지
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• 제22권4호
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• pp.93-98
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• 2014

In this study, control of oxidizer mass flow rate and verification of control system were performed for hybrid rocket thrust control application. Oxidizer flow control system consists of ball valve and stepping motor where gaseous oxygen was used for oxidizer at feeding pressure of 10, 20 and 30 bar. According to experimental results, the oxidizer mass flow rate showed a relatively linear increment as ball valve open angle increases regardless of feeding pressure. In addition, the level of the oxidizer flow rate was kept almost constant at each sequence of flow control with ball valve during the 20 seconds of operation.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.37-40
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• 2003

The thrust vector control using a fluidic counterflow concept is achieved by applying a vacuum to a slot adjacent to a primary jet which is shrouded by a suction collar. The vacuum produces a secondary reverse flowing stream near the primary. The shear layers between the two counterflowing streams mix and entrain mass from the surrounding fluid. The presence of the collar inhibits mass entrainment and the flow m the collar accelerates causing a drop in pressure on the collar. For the vacuum asymmetrically applied to one side of the nozzle, the jet will vector toward the low-pressure region. The present study is performed to investigate the effectiveness of thrust vector control using the fluidic counterflow concept. A computational work is carried out using the two-dimensional, compressible Navier-Stokes equations, with several kinds of turbulence models. The computational results are compared with the previous experimental ones. It is found that the present fluidic counterflow concept is a viable method to vector the thrust of a propulsion system.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.237-240
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• 2007

추진시스템의 추력제어 목적으로 50 N급 PE(폴리에틸렌)-기체산소 하이브리드 로켓을 제작하고, 기체산소의 질유량을 변화시켰다. 기초실험 결과, 기체산소 질유량 제어를 통한 하이브리드 로켓의 추력제어 가능성을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.257-260
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• 2008

추진시스템의 추력제어를 목적으로 50 N급 PE(폴리에틸렌)-GOx(기체산소) 하이브리드 로켓을 제작하고, 기체산소의 질유량을 변화시켰다. 기초실험 결과, 기체산소의 질유량 제어를 통한 하이브리드 로켓의 추력제어 가능성을 확인하였다.

• 전기학회논문지
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• 제67권1호
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• pp.46-51
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• 2018

Constant slip frequency control has been conventionally used in thrust control of the linear induction motor(LIM) for magnetically levitated train. However in this paper variable slip frequency control method is presented to increase LIM efficiency according to change of driving notch. Thrust, attractive force, input power to inverter, regenerative power of the LIM are analyzed by finite element method when the train runs according to the presented control method. As a result it is proved experimentally that the electrical energy to inverter is reduced than the conventional method.

• 제어로봇시스템학회논문지
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• 제20권7호
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• pp.695-700
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• 2014

In this paper, we utilize the CMG's momentum bias to control the roll/pitch attitude of the Quad-rotor. While the previous control approaches have used the thrust control approach, we design and add a new momentum controller (using CMG) in order to improve the transient response over the existing methods. The focal point of this paper is the design of a controller for a Quad-rotor's attitude using CMG. This leads to other tasks such as an identification of the model's parameters and mathematical nonlinear modeling. Then, the previous thrust controller is designed based on the linearized model. Finally, the overall system with our designed controller is implemented and tested in real time to show that the Quad-rotor is kept in a good balanced position faster than the traditional thrust-only control approach.