• Journal of Biomedical Engineering Research
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• 제30권3호
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• pp.199-204
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• 2009

Iridium oxide films (IROFs) have been extensively studied as a material for electrical stimulation of neurons, as iridium oxide has higher charge storage capacity than other metal films. More recently, sputtered iridium oxide film (SIROF) has been studied, because it can be made more conveniently than activated iridium oxide film (AIROF). Typically, the SIROFs are grown at temperatures from 400 to 600 $^{\circ}C$. However, such high temperatures cannot be used when the iridium oxide (IrOx) film is to be deposited on a flexible polymer material, such as polyimide. In this paper, we show that we can still obtain excellent characteristics in SIROFs grown without heating (cold SIROF), by optimizing the growth conditions. We show that the oxygen flow rate is a critical parameter for controlling the surface properties of a cold SIROF. At an oxygen flow rate of 12 seem, the cold SIROF exhibited a charge storage capacity (CSC) of 60 mC/cm$^2$, which is comparable to or better than other published values for iridium oxide films including heated SIROFs. The film produced under these conditions also had the minimum impedance value of all cold SIROFs deposited for this study. A stability test and biocompatibility test also demonstrated the superiority of the optimized cold SIROF.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.289-294
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• 2007

Solid Rocket Motor(SRM) has advantages such as - high specific impulse, operational safety and simplicity in design and manufacturing process, but thrust magnitude can't be controlled. For studying of pintle nozzle that can control the thrust magnitude of SRM, cold flow test and numerical analysis about needle type pintle shape were performed and results were presented in this paper. As the results of this study, pintle tip's shape and nozzle contour were important design parameters because thrust performance and variable thrust range of pintle nozzle depend on them. Especially, the thrust of needle typed pintle nozzle adopted in this test was predicted 13% higher than normal nozzle without pintle.

• Journal of the Korean Society of Propulsion Engineers
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• 제22권1호
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• pp.52-57
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• 2018

This paper presents the design and cold flow test results of oxidizer-rich preburner injectors for a 9 tonf-class staged combustion engine cycle. Three types of coaxial swirl injectors were designed, and 12 injectors were designed for each type. The diameters of the fuel tangential holes are identical. The diameters of the oxidizer tangential holes were varied to investigate the influence of combustion in the oxidizer-rich preburner according to the momentum ratio of the gas oxidizer generated from combustion in the injector chamber and liquid oxidizer through the cooling channel. It will be verified through a powerpack and combustion test using an oxidizer-rich preburner. In the cold flow test, the fuel flow rate and oxidizer tangential hole flow rate reached the target value based on the designed differential pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.95-98
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• 2010

A multi-injector rocket engine using high concentrated hydrogen peroxide and kerosene as the oxidizer and fuel was designed and fabricated. Six coaxial swirl injectors were mounted on the mixing head and flow analysis in the manifold was performed to minimize stagnation and recirculation zones. Finally, uniformity of mass flow rate and spray pattern was evaluated by cold flow tests and the mixing head design process was successfully verified the results.

• Journal of the Korean Society of Propulsion Engineers
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• 제15권6호
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• pp.26-37
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• 2011

A 75-tonf-class LRE(liquid rocket engine) thrust chamber with ablative material for technology demonstration was manufactured on the basis of development technologies of 30-tonf-class LRE. Hydraulic characteristics of the thrust chamber were examined through cold flow test and ignition test of low flow condition. Test result showed that hydraulic function was good. Side ignition method with igniter ring also showed a fine function of ignition in operating ways of static condition. But a close review is required to understand the phenomena of generation and extinction of specific frequencies showed in dynamic characteristics ways. To achieve these, a large combustion test facility which is capable of performing combustion test at design condition of the 75-tonf-class thrust chamber should be constructed as soon as possible.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1016-1020
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• 2017

This study was conducted to develop a test facility that simulates the combustion instability that occurs in a real-scale liquid rocket combustor. A separate engine head with 3 injectors arranged in a row was designed/manufactured and verified through preliminary tests. The flow rate and spray pattern of the head were confirmed by the cold flow test. Next, propellant spray test and combustion test were carried out. A preliminary combustion test was carried out at 10 bar and the combustion chamber pressure was measured to be significantly lower than the target pressure. This is because it was a low pressure test, and it is expected to be resolved in the high pressure test in the future.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.29-33
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• 2009

On the basis of the development experience of a gas generator for the 30 ton-f thrust liquid rocket engine combustor a Subscale Ground Firing Test Facility was designed and fabricated for a gas generator for the 75 ton-f thrust liquid rocket engine combustor. The Subscale Ground Firing Test Facility developed is going to be used to develop 75 ton-f class gas generator. Acquired data and test technique from this facility will be used to develope the high performance liquid rocket engine combustor and the Ground Firing Test Facility. This report describes the improved Subscale Ground Firing Test Facility for 75 ton-f class gas generator and results of the cold flow test.

• Journal of the Korean Society of Propulsion Engineers
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• 제10권2호
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• pp.46-52
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• 2006

Techniques used for thrust vector control in rocket motors are mainly classified nozzles installed mechanical interference on the expansive region of nozzle(such as jet tabs and jet vanes) and movable nozzles(such as ball&socket and flexible seal). Using the numerical analysis and cold-flow test, this paper evaluates the performance of supersonic nozzle with asymmetric entrance shape when the test nozzle, especially ball&socket, is tilted. Numerical result shows that the effect of the asymmetric entrance shape on the flow field is suddenly diminished at the nozzle throat and downstream is mostly free from the effect of asymmetric entrance shape. Although the calculated thrust and lateral force are less than those of cold-flow test, two results show a fairly good agreement. But the cold-flow test results indicate the effective angles calculated from measured forces are not agreement with the geometric angles.

• Journal of the Korean Society of Propulsion Engineers
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• 제27권1호
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• pp.58-67
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• 2023

Results of dry-run tests, cold-flow tests, and hot-firing tests performed to throttle a methane engine uni-element thrust chamber are covered in the paper. After installing flow control valves on the oxidizer and fuel supply lines of the methane engine combustion test facility, a number of dry-run tests were repeated so that the valves could reach set strokes quickly and stably. Then, cold-flow tests using liquid nitrogen and gaseous nitrogen were conducted to confirm the stable supply of the simulated propellants according to the valve control. Finally, using liquid oxygen and gaseous methane, hot-firing tests for fixed and continuous thrust control of 50% to 10% of the nominal thrust were successfully performed.

• Progress in Superconductivity and Cryogenics
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• 제14권4호
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• pp.50-53
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• 2012

This paper describes experimental study on GM-type pulse tube refrigerator (PTR). In a PTR, the pulse tube is only filled with working gas and there exists secondary flow due to a large temperature difference between cold-end and warm-end. The stability of secondary flow is affected by orientation of cold-head and thus, the cooling performance is deteriorated by gas mixing due to secondary flow. In this study, a single stage GM-type pulse tube refrigerator is fabricated and tested. The cooing performance of the fabricated PTR is measured as varying cold-head orientation angle and the results are used as reference data. Then, we divided interior space of pulse tube into three segments, and fixed the various size of screen mesh at interface of each segment to suppress the performance degradation due to secondary flow. For various configuration of pulse tube, no-load test and heat load test are carried out with the fixed experimental condition of charging pressure, operating frequency and orifice valve turns. From experimental results, the fine screen mesh shows the effective suppression of performance degradation for the large orientation angle, but the use of screen mesh cause the loss of cooling capacity rather than the case of no insertion into pulse tube. It should be compromised whether the use of screen mesh in consideration of the installation limitation of a GM-type pulse tube refrigerator.