• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.2
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• pp.144-149
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• 2014

A ground firing test for hot-fire performance evaluation according to the characteristic length($L^*$) variation of thrust chamber was carried out for the hydrazine thruster which may be employed in space launch vehicles. A scrutiny into the performance characteristics of each thruster is made in terms of thrust, specific impulse, response characteristics, and characteristic velocity at steady-state firing mode with propellant inlet pressure of 2.41 MPa (350 psia). Through the test results, it has been verified that performance of characteristic velocity and specific impulse degrades as the characteristic length deviates from that of the standard model. Thus, it is confirmed that the thrust chamber configuration of standard model was suitably designed for the requirement specified.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.911-920
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• 2016

For the pitch and yaw axis attitude control of launch vehicle, thrust vector control which changes the direction of thrust during the engine combustion is commonly used. Hydraulic actuation system has been used generally as a drive system for the thrust vector control of launch vehicles with the advantage of power-to-weight ratio. Nowadays, due to the developments of highly efficient electric motor and motor control techniques, it has done a lot of research to adopt electro-mechanical actuator for thrust vector control of small-sized launch vehicles. This paper describes system design and test results of the prototype of direct drive electro-mechanical actuation system which is being developed for the thrust vector control of $3^{rd}$ stage engine of KSVL-II.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.26-33
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• 2006

The use of high-density propellants can provide performance advantages in space launch vehicles by allowing an improved structural ratio due to smaller propellants tanks. The Jet A-1 fuel is currently used in Korean space launch vehicle development and it has lower density than other advanced hydrocarbon fuels such as RP-1 or RG-1. In this paper, the results of hydraulic and combustion tests conducted for the two newly developed densified hydrocarbon fuels are presented and they are compared with the results of Jet A-1. Conclusively, the two densified hydrocarbon fuels presented equivalent or even higher combustion performance compared to the Jet A-1 and the performance difference was found to be more obvious in the injector of external mixing.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.50-58
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• 2014

This paper is about a short survey on the recent research activities regarding health monitoring and management for liquid rocket engines. For this, we investigate the precedent techniques developed in advanced space-industry countries which are USA, EU, Russia, Japan and China. Particularly, we focus on the technologies applied in China, a recently joined to the advanced space-industry countries in this field. Then we discuss some important points to be considered to apply to the development of the Korea Space Launch Vehicle KSLV-II and other related projects.

• Journal of Aerospace System Engineering
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• v.8 no.2
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• pp.49-54
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• 2014

The main purpose of Korea Space Launch Vehicle II(KSLV-II) Program is to develop a domestic launch vehicle that can deliver a 1.5ton class application satellite into a Low Earth Orbit(600~800km). The data management is an essential factor in systems engineering for success of large-scale complex systems development, and it systematically manages the information and technical data for the total life-cycle of a system. In this paper, data management policies and processes on KSLV-II program are presented, and product life-cycle management system for KSLV-II program is also presented.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.3
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• pp.31-39
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• 2014

In KSLV-I launch mission, real-time data from the tracking stations are acquired, processed and distributed by the Mission Control System to the user group who needed to monitor processed data for safety and flight monitoring purposes. The processed trajectory data by the mission control system is sent to each tracking system for target designation in case of tracking failure. Also, the processed data are used for decision making for flight termination when anomalies occur during flight of the launch vehicle. In this paper, we propose the processing mechanism of slaving data which plays a key role of launch vehicle tracking mission. The best position data is selected by predefined logic and current status after every available position data are acquired and pre-processed. And, the slaving data is distributed to each tracking stations through time delay is compensated by extrapolation. For the accurate processing, operation timing of every procesing modules are triggered by time-tick signal(25ms period) which is driven from UTC(Universial Time Coordinates) time. To evaluate the proposed method, we compared slaving data to the position data which received by tracking radar. The experiments show the average difference value is below 0.01 degree.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.923-928
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• 2008

Pyrotechnic shock or pyroshock is characterized as a transient vibration phenomenon which shows large acceleration and high frequency range up to 10kHz during the operation of separation devices where explosives are used. During the flight of a launch vehicle, pyroshock is mainly generated at several events such as satellite separation, fairing separation and stage separation. In this paper, wiremesh isolators are introduced and several types of isolators are manufactured for the performance tests. For the investigation of typical characteristics of wiremesh isolators, compressive loading tests are basically performed and pyroshock tests are accomplished to confirm pyroshock isolation ability of each wiremesh isolator by using 4Kg dummy mass.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.285-290
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• 2008

Pyrotechnic shock or pyroshock is characterized as a transient vibration phenomena which shows large acceleration and high frequency range up to 10kHz during the operation of separation devices where explosives are used. During the flight of a launch vehicle, pyro-shock is mainly generated at several events such as satellite separation, fairing separation and stage separation. In this paper, characteristics of pyroshock are introduced briefly, and PEEK washer shock absorber is applied for the reduction of pyroshock in the high frequency range. With some electronic devices, reduction characteristic of pyroshock using washer type shock absorber are studied. Random vibration tests are also performed for the verification of vibrational characteristics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.118-123
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• 2018

Coil guns are known worldwide as inexpensive space launch vehicles. The principle of Fleming's right-hand rule allows the coil gun to accelerate the projectile by applying enormous voltage to the solenoid coil. This study was performed to improve the speed of the coil gun using MATLAB, a commercially available numerical program for high launching force of electromagnetic projectiles. To maximize the speed of the projectile, the largest coil of American wire gauge was used, and the number of windings in the radial and axial directions of the solenoid coil was optimized. Optimal length of the projectile was obtained by calculating the optimal aspect ratio between the axial length of the solenoid coil and the length of the projectile.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.86-95
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• 2010

Flight termination system(FTS) is used to terminate safely the launch vehicle's flight when it faces an emergency situation by transmitting termination command from ground FTS. RCC standard IRIG tone method has been used widely for FTS commands method in foreign ranges and Naro Space Center, but this method has a weakness for security of command signal. Therefore RCC had studied more secured EFTS standard and chose CPFSK digital modulation method. This paper describes basic concept and types of FTS and FTS types which foreign ranges had applied and describes standardization of EFTS in the U.S. based on RCC EFTS study reports.