• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.89-95
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• 2017

The improvement of a flow coefficient for the recirculation chill-down flow in a main oxidizer shut-off valve has been presented. The flow coefficient, which is mainly affected by the recirculation outlet port size and the configuration inside the valve, has been predicted with measured flow coefficient values. The comparison of experimentally measured flow coefficient with the predicted value shows the effect of valve inside configuration on the flow coefficient. Consequently, the flow coefficient is twice the previous value and about 75% of the pressure loss assigned to the main oxidizer shut-off valve can be used for additional pressure losses for other components in the recirculation chill-down system of a launch vehicle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.801-807
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• 2020

Opening characteristics of a main oxidizer shut-off valve at different valve inlet pressures have been experimentally investigated. The pilot pressure at the moment of the valve opening increases linearly with increasing the valve inlet pressure and the increased pilot pressure reduces the valve travel time. As the pilot pressure increases at the moment of valve opening, the time to start opening the valve is delayed resulting in increasing the valve opening time. With the increment of the valve inlet pressure, the valve opening time is mainly determined by the time required for the pilot pressure to start opening the valve. Therefore the design of a pilot gas supply system can readily control the valve inlet pressure at the valve opening as well as the amount of oxidizer supplied to a combustion chamber during the engine startup.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.77-83
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• 2020

The operating characteristics of a main oxidizer shut-off valve have been examined by life-cycle tests in which the valve operates as many times as is required at room and cryogenic temperatures. It is shown that there is no significant change of the operating characteristics in the course of the life-cycle tests. The critical pressures and principal forces, which represent the operating characteristics, differ at each operating time by less than about 3%. These qualified operating characteristics of the valve are expected to play an indispensible role in the stable startup and shutdown of a liquid rocket engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.113-119
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• 2013

A main oxidizer shut-off valve (MOV) controls the supply of cryogenic liquid oxygen to the combustion chamber of liquid rocket engines by on/off operations. The main subjects to be introduced are not only the valve transient response during valve on/off procedures but also the characteristics of pneumatic and seat/poppet parts as core technologies in the development of the MOV, which is expected to be adopted for the Korea Space Launch Vehicle II. It is shown that the analytical prediction of the transient valve travel is in good agreement with experimental results. Friction and elastic forces on the valve moving part are quantitatively evaluated by structural analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.417-422
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• 2017

One of the most frightening aspects of weapons of mass destruction (WMD) is their ability to cause death in very small quantities without being visible to the public. The military authorities are making considerable effort to ensure the survivability of the combatants in the event of NBC(Nuclear, Biological and Chemical) contamination. Therefore, in this study, modules were developed for the measurement of the positive pressure and for the detection of the chemicals used for the control of the various shut-off valves used in an NBC shelter. In addition, a high performance gas tight shut-off valve was developed that can overcome the disadvantages associated with manual manufacturing, such as the occurrence of defective products and high manufacturing cost. By applying the positive pressure measurement and chemical detection modules, this valve was able to be used to control the facility. The developed gas-tight shut-off valve maintained airtight characteristics at a pressure loss of 28[Pa] at the prescribed wind velocity and an internal pressure of 30[kPa]. It is expected to be possible to control the gas-tight shut-off valve through the remote measurement of the positive pressure, thereby ensuring the foreign independence of import substitution and defense related technology in the future. In addition, by installing these valves in all of the intake ports or exhaust ports connected to the outside of the NBC shelter, it is possible to prevent the damage resulting from the rapid inflow of the storm pressure caused by conventional weapons and nuclear explosions, thereby protecting the people and equipment in the shelter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.9
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• pp.717-724
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• 2020

We study the closing characteristics of a self-sustainable poppet valve which serves as a main oxidizer shut-off valve for liquid rocket engines. Numerical analysis for predicting closing transient responses are presented and the calculated results have been verified by a comparison with experimental data. The effective area of a pilot gas discharge system and the pressure distribution of passage flow around the valve moving part are shown to be main parameters in determining the closing characteristics for dry and cryogenic conditions, respectively. Moreover, it is presented that the passage flow pressure at the valve closing moment as well as the valve closing velocity can be effectively adjusted by the appropriate employment of the pilot gas.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.91-97
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• 2012

The structural analyses and experimental results for the bellows of a gas-generator liquid oxygen shut-off valve were presented. The bellows experiences axial compression and external high pressure loadings at cryogenic temperatures. The analyses were performed using EJMA (Expansion Joint Manufacturing Association) standard and the commercial FE (finite element) analysis program, Abaqus v6.9, at room and cryogenic temperatures. The spring modulus, the induced stress and the expected fatigue life of the bellows were compared respectively. The effects by the contact and the material plasticity on the FE analysis results were also analyzed. Also, FE analyses related to a burst test were presented.

• The KSFM Journal of Fluid Machinery
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• v.13 no.4
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• pp.11-17
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• 2010

The developed control valves, installed on the hot water distribution manifolds for the floor heating system, consist of the balancing valves and the shut-off valves. The balancing valve was designed to improve the flow control performance and to reduce the noise emitted from the valve by modification of the general V port. The port of the shut-off valve was designed with two ceramic plates, working by rotating upper plate, to improve the duration and to reduce the noise. For the evaluation of the new valves, the flow rate was measured and noise level test was carried out. The test results showed that the error of the flow rate accuracy test for the flow balance of each manifold circuit was less than ${\pm}3%$ and the noise level was less than 35 dB(A).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.219-224
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• 2017

In facing the lack of a deterministic algorithm for economic load dispatch optimization problem, only non-deterministic heuristic algorithms have been suggested. Worse still, there is a near deficiency of research devoted to real-time load dispatch optimization algorithm. In this paper, therefore, I devise a shut-off and swap algorithm to solve real-time load dispatch optimization problem. With this algorithm in place, generators with maximum cost-per-unit generation power are to be shut off. The proposed shut-off criteria use only quadratic function in power generation cost function without valve effect nonlinear absolute function. When applied to the most prevalent economic load dispatch benchmark data, the proposed algorithm is proven to largely reduce the power cost of known algorithms.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.413-416
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• 2009

For the liquid rocket engine, the gas generator oxidizer shut-off valve which supplies the oxidizer to a gas generator needs structural safety under the internal pressure, which is higher than the chamber pressure. In this study, static stress analyses of the various design in the vicinity of the region where the stress is concentrated were performed for designing the lightweight valve, A lightest model of which the concentrated stress does not exceed the yield criteria has been suggested. Also, whole size effect of the valve on the concentrated stress was investigated.