• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.175-181
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• 2016

In this paper, the liquid air was selected as the refrigerant in artificial ground freezing to be used for rapid ground freezing and to reduce the risk of suffocation and the applicability of liquid air was verified. In order to evaluate the stability of the liquid air, the oxygen concentration of mixtures with liquid nitrogen and liquid oxygen was experimentally examined to meet the oxygen concentration criteria in the Occupational Safety and Health Act. In addition, the effects of the mixture ratio of liquid nitrogen and liquid oxygen, pressure and flow rate change in the storage vessel on the oxygen concentration in the liquid air were investigated. As a result, the ratio of liquid nitrogen and liquid oxygen 8: 2 was shown to meet the oxygen concentration standards. Pressure and flow rate change in the storage vessel did not have significant effects on the oxygen concentration in the liquid air.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.123-131
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• 2002

In this paper, characteristics of cryogenic liquid oxygen was examined during cold flow of KSR-III main engine at each stage. The effect of venting was examined at the stage of cooling and at the pressurization stage, the interaction between nitrogen gas and liquid oxygen was also examined. The characteristic of liquid oxygen in the engine manifold was analyzed. The results showed that venting was the primary role at the cooling process and the interaction of nitrogen gas and liquid oxygen in the run tank is limited at the surface area. With the sampling rate of 1KHz static and dynamic pressure were measured in the rocket engine manifold and in the LOX supply equipment. 32.5mm and 38mm orifice were installed for the tests and pressure condition of liquid oxygen was 23Bar, 29Bar, 41Bar. Increase of orifice diameter and decrease of supply pressure reduced the perturbation of pressure in engine manifold.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.51-54
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• 2010

Physical characteristics of liquid and gaseous oxygen and the detailed ignition characteristics of oxygen system were introduced. Compatible and non-compatible materials for oxygen were discussed. To ensure the safety operation of the oxygen system, one of the most important point, cleaning, was reviewed. To design the gaseous and liquid oxygen system, key points were introduced. To safe operation, the operating procedure and considerations were introduced.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.179-182
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• 2005

Test of liquid oxygen sub-cooling by helium injection, which is one of the method of temperature conditioning of cryogenic propellant in liquid propulsion rocket, is performed. The sub-cooling effect at different He injection flow rate with the same initial liquid oxygen mass is compared. Test results showed liquid oxygen temperature decrease of $5\sim6^{\circ}C$ under test condition. And the required time for cooling is inversely proportional to He injection flow rate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.793-794
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• 2011

In launch process, propellants should be supplied with established temperature range for engine normal operation. In order to satisfy this temperature condition, propellant feeding systems should be considered some effects during operation. This paper studied liquid oxygen filling system operation process and cooling method of liquid oxygen during launch process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.805-811
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• 2009

An oxidizer pump of a turbopump for a 30-ton class gas generator cycle engine was tested in the medium of liquid oxygen. The turbine was driven by cold hydrogen gas in the test. The oxidizer pump was operated stably at both design and off-design conditions, satisfying the performance requirements. The pump head coefficient from the liquid oxygen test was 2~3% lower than that from the water test. The power required to run the oxidizer pump was well balanced with the power produced by the turbine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.34-37
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• 2007

Propellant filling and holding test was carried out using liquid oxygen as a working fluid. The feeding line system has a filter at propellant tank outlet. Vaporization of liquid oxygen during holding after completion of filling and effect of vaporization to recirculation performance in this system was observed. Filling rate and pressure of tank ullage had the effect on state of liquid oxygen in feeding line. There was no geysering in feeding line during holding because of the position of filter.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1171-1175
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• 2017

Cryogenic helium gas is used as the pressurant for the oxidizer pressurization of DR(Damper Receiver) sphere in the PSD(Pogo Suppression Device) system and liquid oxygen is used as the oxidizer for the propellant in Korea Space Launch Vehicle-II. The helium gas is stored in pressurant cylinders inside the cryogenic liquid oxygen tank and liquid oxygen is stored in the oxidizer tank. In this study, the performance test of PSD liquid oxygen drain valve for KSLV-II was considered.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.108-116
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• 2018

A firing test of the 75 tonf-class liquid rocket engine to be used as the first and second stage engines of the KSLV-II was carried out at the rocket engine test facility(RETF). Since this engine uses liquid oxygen as the oxidizer, which is a cryogenic fluid, it is essential that the chill down of the supply pipe line and engine proceed for the firing test; thus, the given inlet requirements must be met. Moreover, it is important to understand the chill down characteristics of the facility and the engine and the amount of liquid oxygen consumed in the chill down process for efficient test operation in the future. In this paper, chill down characteristics of the supply pipe and the engine were evaluated through the investigation of the chill down process of the 75 tonf-class liquid rocket engine at each stage before and after run tank pressurization. In addition, the amount of liquid oxygen consumed was also evaluated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.309-312
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• 2009

The various hazards should be eliminated before operations for the successful launches or tests. Using the contaminated propellants is one of the causes for the launch and test failures. Especially, the systems using liquid oxygen as an oxidizer have risks about fires and explosions not be forecasted if they are contaminated by oil, water and mechanical impurities. The procedure for the quality control of the liquid oxygen and the liquid oxygen filling system and the lessons learned from the first launch preparation with the system are introduced on this paper.