• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.77-84
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• 2006

With the development of micro/nano spacecraft, concepts of micro propulsion are introduced for orbit transfer and drag compensation as well as attitude control. Micro solid propellant thruster has been attention as one of possible solution for micro thruster. In this paper, micro solid propellant thruster is introduced and research on basic components of a micro solid propellant thruster is reported. Micro Pt igniter was fabricated through negative patterning and quantitative effect of geometry was estimated. The characteristic of HTPB/AP solid propellant was investigated to measure the homing velocity. A combustion chamber was fabricated by means of anisotropic etching of photosensitive glass. Finally, micro solid propellant thrusters having various geometries were fabricated and tested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.66-68
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• 2011

Chollian is a geostationary satellite, and its bipropellant propulsion system is mainly composed of one main engine for orbit transfer and fourteen thrusters for on-station operations. The Chollian was launched successfully at Kourou Space Center in French Guiana. After it separated from the launcher, the propulsion system was initialised automatically. Then three times of main engine firing were successfully performed, and the target obit insertion was accomplished. This paper details the major CPS events during LEOP phase for the Chollian satellite.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.137-144
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• 2001

This paper presents the REA thrusters performance estimation results for the KOREASAT F1&F2 launched in 1995 The satellite tracking data obtained from the ground system from end of 1999 to beginning of the 2000 are used to estimate the thruster performance. The estimation algorithm is derived from the least square estimation theory and designed to estimate the velocity change induced by the on-boarded thruster firing as well as the orbit parameter. The estimation results show that the Koreasat F1 thruster are in bad thruster condition of 64% performance for REA when it fires in on-pulse mode. Here, the performance is defined by the ratio of the resulted velocity change to that of planned. But, in the case o( the Koreasat F2, it is found that the performance approximately reaches up to 100%, even after the 5 years of the mission.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.146-149
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• 2006

Spray characteristics of an injector employed in mono-propellant hydrazine thrusters were investigated by PIV(particle image velocimetry) and LDA/PDA(laser/phase Doppler anemometry) techniques. The instanteneous plane image data captured by PIV measurement were examined in order to judge a pass-fail criteria of spray injection performance according to the specific pressure supplied. LDA/PDA technique were also applied to measure the velocity and droplet size of spray were not obtained from PIV measurement. The objective of this experimental study was the clear understanding of spray characteristics as well as the derivation of injector performance to understand clearly the spray characteristics by comparing the both results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.407-412
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• 2006

Most of the monopropellant thrusters use catalyst for decomposing hydrazine. The thruster lifetime is determined mainly by catalyst lifetime, which can be investigated by firing tests. For the development of hydrazine decomposition catalyst, Hot-fire test to verify long-life performance of catalyst is required. This study describes the development of test equipment for long duration hot-firing and test/evaluation plan.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.19-27
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• 2010

KSLV(Korea Space Launch Vehicle)-I is designed as a launch vehicle to enter a 100 kg-class satellite to the LEO(Low-Earth Orbit). Attitude angles of the upper-stage, including roll, pitch and yaw are controlled by cold gas thruster system using nitrogen gas. The thruster for the KSLV-I is the main pneumatic valve in the RCS(Reaction Control System). In this paper, the design, function tests, and environment tests of the thruster for KSLV-I are described. The developed thrusters are experimentally evaluated and successfully passed the required qualification and acceptance tests.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.487-490
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• 2010

A fluid transient analysis on the pipe network of bipropellant propulsion system is conducted through numerical parametric studies in which unsteady friction results are compared with quasi-steady friction results and also show the pressure drop results during the liquid apogee engine firing. The fluid transient analysis program has verified through comparing with the original Zielke model, the full and recursive convolution model and quasi-steady model as a reference. And the pressure drop program also has verified through comparing with results of the well-known program, EPANET2. The bipropellant propulsion system has two different fluids as fuel and oxidizer, and mostly they are hypergolic combination so that the valve opening and closing of the thrusters, that cause the pressure waves, shall take place simultaneously to get proper performance. The different physical properties of the fuel and oxidizer result in the different responsive to the same valve opening and closing. The response results may be helpful to know the characteristics of the bipropellant propulsion system and design it.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.7
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• pp.935-941
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• 2012

This paper describes a study of conventional electrical rig and simulated application of Flywheel Energy Storage system on the power system of the offshore plants with dynamic positioning system with the following aims: improve fuel consumption on engines, prevent blackout and mitigate voltage sags due to pulsed load and fault. Fuel consumption has been analyzed for the generators of the typical drilling rigs compared with the power plant with Flywheel Storage Unit which has an important aid in avoiding power interruption during DP (Dynamic Positioning) operation. The FES (Fly wheel Energy storage System) releases energy very quickly and efficiently to ensure continuity of the power supply to essential consumers such as auxiliary machinery and thrusters upon main power failure. It will run until the standby diesel generator can start and supply the electric power to the facilities to keep the vessel in correct position under DP operation. The proposed backup method to utilize the quick and large energy storage Flywheel system can be optimized in any power system design on offshore plant.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.1
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• pp.1-10
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• 2010

Design and performance evaluation of $H_2O_2$ monopropellant thrusters to be used at reaction control of space launch vehicles were presented in this paper. Design thrust level was determined as 100, 250 Newton which is nominal thrust level for commercial space launch vehicles. Qualification thruster models including solenoid valves were developed after the reactor design were evaluated at engineering thruster models. Each thruster was evaluated by measurement of characteristic velocity, thrust, specific impulse, and pulse response times at sea level test condition.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.359-362
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• 2006

This study develops an automatic berthing control algorithm for ships with a bow thruster and a stern thruster as well as a rudder. A nonlinear mathematical model for low speed maneuvering of ships is used to develop a MIMO(multi-input multi-output) nonlinear control algorithm. The algorithm consists of two parts, which are forward velocity control and heading angle control. The control algorithm is designed based on the longitudinal and yaw dynamic models of ships. The desired heading angle is obtained by the so called "Line of Sight" method. An optimal control force allocation method of the rudder and the thrusters is suggested. The nonlinear control algorithms are tested by numerical simulations using MATLAB, and shows good tracking performances.