• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1989.06b
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• pp.60-69
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• 1989

안정성과 진동억제 특성이 요구되는 터어빈이나 모터등의 고속 회전기계에서는 틸팅-패드 저어널 베어링이 많이 사용되고 있다. 이는 틸팅-패드 저어널 베어링에서는 패드가 피봇이나 로울러로 지지되어 있으므로 윤활유막에서 발생하는 압력의 합력중심이 항상 이 지지점을 지나게 되어 베어링의 안정특성이 향상되기 때문이다. 틸팅-패드 저어널 베어링은 추력 베어링과 같이 불연속적인 윤활면을 갖는다. 그러므로 베어링의 입구부 선단에서 공급되는 윤활유의 충돌로 인한 압력격변이 일어나는데 이때 패드 입구부에서 발생하는 압력을 선단압력이라 한다. 이러한 선단압력으로 인한 베어링의 성능변화에 관한 연구는 주로 추력 베어링에 대하여 이론 및 실험적으로 수행 되어져 왔으며 그 결과들은 선단압력이 베어링의 성능에 미치는 영향을 무시할 수 없음을 보여주고 있다. 그러나 아직도 선단압력의 영향이 제대로 파악되고 있지 못하며, 특히 틸팅-패드 저어널 베어링에서 선단압력의 영향을 조사한 연구는 많이 부족한 실정이다. 그러므로 본 연구에서는 유한폭 틸팅-패드 저어널 베어링을 모델화한 실험장치를 설계 제작하여 선단압력을 포함한 유막내의 압력분포 및 유막두께를 연속적으로 측정함으로써 틸팅-패드 저어널 베어링의 성능에 미치는 선단압력의 영향을 실험적으로 조사하기로 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.26-34
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• 2008

The performance of several catalysts to decompose the high test peroxide (HTP) was described in this paper. Manganese oxide, Platinum and Iridium were coated on the gamma alumina. The catalyst activity as active materials was measured at the flask reactor. The response time of various catalysts was also measured with a 50 Newton class thruster. $Ir/Al_2O_3$ that showed the best activity in the flask reactor and response time at the thruster, failed the reaction when continuous mode test was carried out with the thruster. $Pt/Al_2O_3$ and $MnO_2/Al_2O_3$ can be substitutes to decompose the HTP. In addition, for larger thruster, $MnO_2/Al_2O_3$ can be a good catalyst because its cost is below 5 % of $Pt/Al_2O_3$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.116-122
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• 2016

The performance characteristics of a TBCC engine considering the transition mode from a turbojet to a ramjet engine has been investigated. The performance of each engine was proposed and a transition mode of the TBCC engine has been evaluated by adjusting the operating rate of the ramjet engine and turbojet engine performance changes continuously. Based on the transition model, it was confirmed that the performance is continuously changed at various flight Mach numbers and altitudes. The performance characteristics including thrust and specific impulse considering various flight conditions and transition mode were analyzed, which testifies characteristics of the engine itself, as well as transition of the combined cycle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.61-64
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• 2008

For the performance evaluation of liquid mono-propellant thruster, Vacuum Hot-fire test is necessarily required. An accurate flow measurement is one of the key parameters to the successful T&E program. This paper describes the characteristics of the coriolis flowmeter, explains the cold-flow test using simulant propellant (DIW), and presents the test results. Finally, the cold test results have been verified in comparison with the hot-fire test data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.9
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• pp.658-664
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• 2019

In the development of the liquid rocket engine using the pintle injector, spray characteristics such as spray angle, droplet size, and distribution of the droplets are dominant parameters. Three different kind of multi hole type pintle tip and a continuous type pintle tip were designed. In the case of multi hole pintle tip, SMD result did not have a significant difference depending on the number of holes. In analysis with visualization images, however, the droplets were uniformly distributed as the number of holes increased. Liquid droplets from continuous type pintle tip were finely atomized and dispersed uniformly than those from multi-hole type pintle tip. In addition, the thrust control by adjusting the liquid injection area of the pintle is suitable for the continuous type, which is easier to face-shutoff rather than the multi hole type. The spray angle of each pintle tip according to TMR was measured to derive a specific tendency and corresponding empirical formula.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.725-738
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• 2006

The final purpose of this study is to develop noise abatement procedures for minimizing damages caused by aircraft noise, to establish appropriate noise limits and to suggest a plan for imposing surcharges and penalties on aircraft infringing the noise limits. This study establishes noise abatement procedures and suggests a plan to complement and improve upon NMS in Gimpo International Airport by reviewing the NMS structure. In addition, this study establishes a noise limit at each noise monitoring system and a verification system to discriminate infringing aircraft. Finally, this study suggests a control plan for aircraft infringing the noise limit.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.379-390
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• 2007

The final purpose of this study is to develop noise abatement procedures for minimizing damages caused by aircraft noise, to establish appropriate noise limits and to suggest a plan for imposing surcharges and penalties on aircraft infringing the noise limits. This study establishes noise abatement procedures and suggests a plan to complement and improve upon NMS in Gimpo International Airport by reviewing the NMS structure. In addition, this study establishes a noise limit at each noise monitoring system and a verification system to discriminate infringing aircraft. Finally, this study suggests a control plan for aircraft Infringing the noise limit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.353-357
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• 2017

The research trends and major technologies of the divert attitude control system(DACS), which is the core of the anti-missile system, are described. The operating concept and characteristics according to the fuel used are summarized. The characteristics of typical weapon system applying solid(SM3 Block IB/IIA) and liquid(THAAD) fuels were discussed. In the future, it will be necessary to study various types of DACS in the strategic concept of the defense weapon system.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.110-116
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• 2008

This paper gives a brief summary of the TVC battery design description, specifications and test results. The TVC battery for KSLV-I upper stage contains 168 Sony l8650VT high power lithium-ion cells. It configured as 2 strings in parallel, with each string containing 84 series connected cells. This allows to meet nominal 270V voltage and capacity requirements specified for the mission of the Thrust Vector Control(TVC) system. The loads profile of the TVC system has short duration, high current pulse. To power such a system with minimal mass, the battery employed l8650VT Cells. This cell is specifically designed for high rate applications and is capable of a 10C continuous discharge.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.495-504
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• 2014

Solar sail spacecrafts can gain propulsion using the momentum change through reflecting the photon packets of energy from the Sun. The sail slowly but continuously accelerates to accomplish a wide-range of potential missions. To develop the potential mission of the solar sail, the configuration, the film characteristics and the deployment devices should be carefully considered. In this paper, recent development and activities of the solar sail are introduced and design technology of the sail subsystem is investigated.