• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.37-46
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• 2013

The gas jet from a coaxial porous injector for two-phase flows is discharged radially from the porous surface, which encloses the center liquid jet. Several hot-firing test using ethanol/nitrous oxide propellants was conducted to analyze the effect of oxidizer/fuel ratio on the combustion performance, and the uncertainty analysis was performed for the results. The characteristic velocity was affected by oxidizer/fuel ratio similarly with the results of CEA calculation except that the maximum characteristic velocity was appeared in the stoichiometric ratio. The characteristic velocity efficiency was increased as the oxidizer/fuel ratio increases.

• Transactions of the KSME C: Technology and Education
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• v.4 no.2
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• pp.93-99
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• 2016

High pressure nozzles and turbines of a gas turbine engine should be required to be operated under extreme operating conditions in order to maximize the performance. Engine manufactures have utilized nickel-base superalloys, enhanced cooling design, and thermal barrier coating techniques to overcome them and furthermore, material modeling, finite element analysis, optimization techniques, and etc. have been utilized widely for elaborate predictions. We aim to evaluate the effects on the low cycle fatigue life of the high pressure turbine blade caused by thermal barrier coatings and the cooling design of the endwall of the first stage turbine nozzle. To achieve it, the structural analysis, which utilized the results of conjugate heat transfer analysis as loading boundary conditions, was performed and then the results were the input for the assessment of low cycle fatigue life at several critical zones.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.182-188
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• 2021

In this paper, using a transfer function-based analytical model, major factors influencing the acoustics and combustion instability in a two-stage duct system composed of a nozzle and a combustor were derived and their quantitative effects were evaluated. From the acoustic analysis, it was confirmed that the change in reflection coefficient and mean flow could have a great influence on the instability growth rate, and the area ratio and speed of sound ratio between the nozzle and the combustor are also key parameters to determine combustion instability as well as flame transfer functions.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.209-215
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• 2005

A qualification of propellant for a AKM(Apogee Kick Motor) has been conducted by firing standard motors. The Standard motor used in developing process of KSLV-I's AKM is ST-6 whose diameter is about six inches. HTPB composite propellant are used in these motors. Several standard motors are fired and compared with simulation results. A mean value of characteristic velocity is 1518 m/s. The characteristic value for prediction is 1516 m/s, and the thrust loss is about 5.9%. Differences between the measurements and prediction are less than 3%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.75-78
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• 2005

The present work has been studied to investigate the effect of formulation on friability of HTPB/AP propellants including Butacene and $Cr_{2}O_3$. The mechanical properties and burning rate of the propellants were measured using Inston tensile tester and strand burner, respectively. Friability was calculated by shot-gun and closed bomb test. The result showed that friability was higher, as the content of Butacene or AP $6{\mu}m$ in the propellant formulations was increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.245-248
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• 2011

A multi pulse rocket motor(MPRM) has several advantages compared to the single one. The range and the terminal velocity of the guided missile can be remarkably increased by the application of the pulse separation device(PSD) to the solid rocket motor which resulted in appropriate thrust distribution. In this study, the full scale heavy type dual pulse rocket motor with the bulkhead type PSD was designed, manufactured, and fire-tested. The bursting time and pressure of PSD were analyzed by the pressure, thrust and vibration results of static fire tests. As a result, the design requirement was verified that bursting pressure is lower than 30% of 2nd pulse operating pressure.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.147-152
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• 2014

In this research, polysulfone hollow fiber membrane was used to recover $CO_2$ which is one of greenhouse gases from flue gas stream being emitted after the combustion of fossil fuels. The prerequisite requirement is to design the membrane process producing high-purity $CO_2$ from flue gas. For separation of $CO_2$, a membrane module and flue gas containing 10% carbon dioxide was used. The effects of operating conditions such as pressure, temperature, feed gas composition and multi-stage membrane on separation performance were examined at various stage cuts. Higher operating pressure and temperature increased carbon dioxide concentration and recovery ratio in permeate. Recovery ratio and separation efficiency increased if a higher content of $CO_2$ injection gas composition. Three-stage membrane system was producing a 95% $CO_2$ with 90% recovery from flue gas. The separation efficiency of three-stage membrane system was higher than one-stage system.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.82-87
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• 2014

Dual pulse rocket motor has a rocket motor with different pulse grains divided by a pulse separation device such as a fragile bulkhead or a thermal barrier type. It distributes thrust energy very effectively via pulse separation device to improve range and terminal velocity of a missile. This paper contains the thermal barrier design and experimental analysis through ground firing tests of small dual pulse motors. The results will be applied to the design, test and evaluation of the scale up dual pulse rocket motor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.133-136
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• 2003

우주발사체의 2단에 사용가능하며, 케로신과 액체산소를 추진제로 하는 10톤급 액체로켓엔진 (LRE)에 대해 노즐 설계 변수와 성능 특성과의 관계를 파악하고 노즐 성능의 개선을 위해 노즐 형상에 따른 성능 해석을 수행하였다. 본 연구에서 10톤급 LRE의 형상을 설계하였으며, 기존의 일차원 성능해석 방법과는 달리, 2차원 유동 해석 결과를 이용한 성능 해석을 수행하기 위해 노즐 성능해석용 코드를 개발하였으며, 액체 산소/메탄 엔진 (LNG 엔진)에 대한 지상 연소시험 결과와 비교, 검토하여 노즐 성능해석 코드를 검증하였다.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.616-620
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• 1998

Zn_{0.994}Mn_{0.006}Ga_2O_4$ green phosphor powders were synthesized using polymerized complex and solution combustion methods, and their powder and luminescence properties were characterized by XRD, SEM, BET, PL, etc. The properties were compared with those of the powders prepared by a solid state reaction method. The powders prepared by polymerized complex and solution combustion methods showed only a single spinel phase at 50$0^{\circ}C$ and 40$0^{\circ}C$, respectively. Their particle sizes were smaller than that of a solid state reaction method. Emission intensity of the phosphor powders prepared by both methods were highest at 90$0^{\circ}C$ and 40$0^{\circ}C$, respectively.