• Journal of the Korean Society of Propulsion Engineers
• /
• v.13 no.4
• /
• pp.22-29
• /
• 2009

Development of Moon Explorer-1 (orbiter) is supposed to be commenced in 2017 and launched in 2020. In case of Moon Explorer-2 (lander), it would be slated to start in 2021 and launch in 2025. In this paper conceptual feasibility studies are conducted for the propulsion system applicable to a Moon Explorer. In the first place the availability of monopropellant/bipropellant/electric propulsion system is examined with domestic as well as overseas precedents. Secondly ${\Delta}V$ is estimated by the mission analysis and the propellant budget is calculated accordingly. Subsequently feasibility of a chemical propulsion system for a Moon Explorer is evaluated.

• Advances in aircraft and spacecraft science
• /
• v.6 no.5
• /
• pp.427-442
• /
• 2019

Small satellites represent an emerging opportunity to realize a wide range of space missions at lower cost and faster delivery, compared to traditional spacecraft. However, small platforms, such as CubeSats, shall increase their actual capabilities. Miniaturized electric propulsion systems can provide the satellite with the key capability of moving in space. The level of readiness of miniaturized electric propulsion systems is low although many concepts have been developed. The present research intends to build a flexible test platform for the assessment of selected small propulsion systems in relevant environment at laboratory level. Main goal of the research is to analyze the mechanical, electrical, magnetic, and chemical interactions of propulsion systems with the modern CubeSat-technology and to assess the performance of the integrated platform. The test platform is a 6U CubeSat hosting electric propulsion systems, providing mechanical, electrical and data interfaces, able to handle a variety of electric propulsion systems, thanks to the ability to regulate and distribute electric power, to exchange data according to several protocols, and to provide different mechanical layouts. The test platform is ready to start the first verification campaign. The paper describes the detailed design of the platform and the main results of the AIV activities.

• Journal of Sensor Science and Technology
• /
• v.33 no.4
• /
• pp.216-223
• /
• 2024

Electric propulsion systems, including electrothermal, electrostatic, and electromagnetic thrusters, are promising systems for producing thrust from satellites. These systems generally operate under vacuum plasma conditions and exhibit high specific impulses and thrust-to-weight ratios. Despite their high efficiencies, electric propulsion systems are susceptible to performance variations due to physical factors such as plasma instabilities, which require an accurate diagnosis of their status during operation. In this study, we review various measurement systems adopted to diagnose electric propulsion systems operating under vacuum conditions. Specifically, we review electrical, optical, and other methods that can directly or indirectly measure the status of a thruster, with a particular focus on Hall effect thrusters. The system configurations and fundamental mechanisms of the different measurement systems are described based on case studies of the diagnosis of propulsion systems. We anticipate that this study will contribute to the efficient development and safe operation of electric propulsion systems for use in artificial satellites.

• Physical Therapy Korea
• /
• v.11 no.4
• /
• pp.7-17
• /
• 2004

Individuals who propel wheelchairs have a high prevalence of upper extremity injuries (i.e., carpal tunnel syndrome, elbow/shoulder tendonitis, impingement syndrome). Musculoskeletal injuries can result from overuse or incorrect use of manual wheelchairs, and can hinder rehabilitation efforts. To better understand the mechanisms of upper extremity injuries, this study investigates the motion of the wrist during wheelchair propulsion. This study also examines changes in the variables that occur with fatiguing wheelchair propulsion to determine how the time parameters of wheelchair propulsion and the state of fatigue influence the risk of injury. A two dimensional (2-D) analysis of wrist movement during the wheelchair stroke was performed. Twenty subjects propelled a wheelchair handrim on a motor-driven treadmill at two different velocities (50, 70 m/min). The results of this study were as follows; The difference in time parameters of wheelchair propulsion (cadence, cycle time, push time, recovery time, and PSP ratio) at two different velocities was statistically significant. The wrist kinematic characteristics had statistically significant differences at two different velocities, but wrist radial deviation and elbow flexion/extension had no statistically significant differences. There were statistically significant differences in relation to fatigue in the time parameter of wheelchair propulsion (70 m/min) between initial 1 minute and final 1 minute. The wrist kinematic characteristics between the initial 1 minute and final 1 minute in relation to fatigue had statistically significant differences but the wrist flexion-extension (50 m/min) had no statistically significant differences. According to the results, the risk of musculoskeletal injuries is increased by fatigue from wheelchair propulsion. To prevent musculoskeletal injuries, wheelchair users should train in a muscle endurance program and consider wearing a splinting/grove. Moreover, wheelchair users need education on propulsion posture, suitable joint position, and proper recovery patterns of propulsion.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.1
• /
• pp.34-38
• /
• 2016

Recently, electric propulsion systems are been increasingly used in large cruise ships and merchant vessels. When abnormal electrical conditions occur in the motor of an electric propulsion ship, they can cause serious damage to the motor and propeller shaft. Research on abnormal conditions of propulsion motors used in electric propulsion vessels and electric ships difficult to find. In this study, a mathematical model of the electric propulsion system is proposed to analyze transient phenomena that occur in the case of electric propulsion motor or propeller shaft malfunction. A synchronous motor was used in the MATLAB computer simulation of this study. In the event of electrical malfunction of the electric propulsion motor at rated operation, over current occurs in the condition of 1 phase ground, over torque occurs at 3 and 2 phases ground and over current and torque occur when exciting power fails at rated operation.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.8
• /
• pp.695-701
• /
• 2016

Spacecraft propulsion system is a kind of rocket engine that has been developed from the end of 1950s for attitude control and orbit maintenance of satellite. Since the spacecraft propulsion system has to be used for a relatively long time, therefore, stability of propellant and life of thruster could be very important factor for propulsion system design. Recently, green propellant propulsion and all electrical propulsion system have became very important issue, and we also need a development according to well organized plan. In this paper, we will introduce the development status, key technologies and development prospect of spacecraft propulsion system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.513-520
• /
• 2004

A steady-state/transient performance simulation model was newly developed for the propulsion system of the CRW (Canard Rotor Wing) type UAV (Unmanned Aerial Vehicle) during flight mode transition. The CRW type UAV has a new concept RPV (Remotely Piloted Vehicle) which can fly at two flight modes such as the take-off/landing and low speed forward flight mode using the rotary wing driven by engine bypass exhaust gas and the high speed forward flight mode using the stopped wing and main engine thrust. The propulsion system of the CRW type UAV consists of the main engine system and the duct system. The flight vehicle may generally select a proper type and specific engine with acceptable thrust level to meet the flight mission in the propulsion system design phase. In this study, a turbojet engine with one spool was selected by decision of the vehicle system designer, and the duct system is composed of main duct, rotor duct, master valve, rotor tip-jet nozzles, and variable area main nozzle. In order to establish the safe flight mode transition region of the propulsion system, steady-state and transient performance simulation should be needed. Using this simulation model, the optimal fuel flow schedules were obtained to keep the proper surge margin and the turbine inlet temperature limitation through steady-state and transient performance estimation. Furthermore, these analysis results will be used to the control optimization of the propulsion system, later. In the transient performance model, ICV (Inter-Component Volume) model was used. The performance analysis using the developed models was performed at various flight conditions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the turbine inlet temperature overshoot limitation as well as the compressor surge margin. Because the engine performance simulation results without the duct system were well agreed with the engine manufacturer's data and the analysis results using a commercial program, it was confirmed that the validity of the proposed performance model was verified. However, the propulsion system performance model including the duct system will be compared with experimental measuring data, later.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.79-82
• /
• 2005

The hybrid rocket has been known for over 50 years. It is safe and cheap but wasn't widely used for the deficit of low regression rate. However, the hybrid rocket propulsion system will replace a lot of fields of missiles, rockets and propulsion systems of launch vehicles with new development of paraffin based solid fuel composition

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.77-83
• /
• 2009

In this study, we conducted resistance and propulsion performance test of ship composed of the Resistance Test, Propeller Open Water Test and Self Propulsion Test using the CFD(Computational Fluid Dynamics). We used commercial RANS(Reynolds Averaged Navier Stokes equation) solver, as a calculating tool. The unstructured grids were used in a bow and stern of ship, having complex shape, for a convenience of generating grids, and the structured grids were adopted in a central hull and rest of hull having a relatively simple shape which is called hybrid grid method. In addition, The sliding mesh method was adopted to rotate a propeller directly in the Propeller Open Water and Self Propulsion Test. The Resistance Test and Self Propulsion Test were calculated using Volume of Fluid (VOF) model and considering a free surface. And all The three cases were applied realizable k-epsilon model as the turbulence model. The results of calculations were verified for the suitability of calculations by comparing MOERI's EFD results.

• Journal of Advanced Marine Engineering and Technology
• /
• v.17 no.3
• /
• pp.50-59
• /
• 1993

Usually ship is propelled by the conventional propeller. When the conventional propeller is used for ship's propulsion, reduction of propeller noise is big issue in some special vessel. In order to reduce the acoustic noise of the propeller, novel propulsion system named as MHD propulsion system has been studied among researchers. In this paper, thruster characteristic analysis and system analysis of MHD propulsion system have been carried out. Firstly basic experimental apparatus is designed, fabricated and installed and test is carried out. Test results are compared with numerical analysis. It is confirmed that test results agreed with numerical results satisfactorily.