• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1002-1004
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• 1996

In this paper, presented are the results of observability analysis for the vehicle maneuver during In-Flight Alignment of SDINS. The target system for observability analysis is 10th order one. Three trajectories for IFA are considered. To analyze the observability of the time varying system, correlation coefficient is used and to measure the degree of observability of the given system, simulation is carried out using covariance matrix. The results of simulation show that trajectories which are having continuous changes in attitude and acceleration of system is superior to straight trajectory in correcting navigation errors.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.217-224
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• 2023

The Korea Pathfinder Lunar Orbiter (KPLO), also known as Danuri, successfully entered its mission orbit on December 27, 2022 (UTC), and is currently performing its mission smoothly. To mitigate potential contingencies during the flight and to navigate the spacecraft into the desired lunar orbit, the KPLO flight dynamics (FD) team analyzed major trajectory-related contingencies that could lead to the violation of mission requirements and prepared operational procedures from the perspective of trajectory and FD. This paper presents the process of preparing contingency trajectory operations for the KPLO, including the identification of trajectory contingencies, prioritization results, and the development of recovery plans and operational procedures. The prepared plans were successfully applied to address minor contingencies encountered during actual operations. The results of this study will provide valuable insights to FD engineers preparing for space exploration mission operations.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.1-8
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• 2009

This thesis has analyzed the effect of the surge happening in flight on the engine performance, especially on the PW4000 turbofan engine. It is to be judged that the flight surge can occur more often at the time of takeoff than it does en route due to the fact that the engine parameters are prone to fluctuate. EPR is judged to be the most highly sensitive parameter responding when surge occurs. Both Engine rpm and Wf decrease almost simultaneously just like an EPR. During the take-off rolling, N1 vibration is more sensitive than the N2 vibration. Consequently, the surge can be detected by EGT increase, while the other parameters (EPR, rpm, Wf, etc) decrease.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.82-89
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• 2012

The temperature of cryogenic propellant in the propellant tank increases during flight due to heat input from surroundings. The propellant which temperature rises up over the required condition of turbo-pump remains as unusable propellant at the end of flight. In this paper the estimation method of the heat transfer coefficient at the upper layer of cryogenic propellant was presented. The heat transfer mode at the propellant upper layer was considered as conduction. Temperature distributions near propellant surface obtained from heat transfer coefficient were compared with test data to show the possibility of this method.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.91-96
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• 2014

KSLV-I (Korea Space Launch Vehicle-I) upper stage KM (Kick Motor) is a solid propulsion system which consists of igniter, SAD (Safety Arming Device), composite case, and submerged nozzle capable of TVC (Thrust Vector Control) actuation. Each subsystem of KM fulfilled development requirements for achieving a flight mission successfully. We confirmed the successful development of KM from the $3^{rd}$ flight test results of NARO on January 30, 2013. This article deals with the requirements of KM and the results on configuration management, mass variation, thrust axis alignment, and major test results and so on.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.8-8
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• 2000

In this paper are presented main power and gasdynamic characteristics of C-l6VK hypersonic test cell of Research Test Center of CIAM. Gasdynamic adjustment of the C-l6VK test cell was carried out with the working section constructed on scheme of Ramjet/scramjet test in free stream. Gasdynamic adjustment was conducted stage by stage in tile following sequence. First, check and preparation of all technical systems and checking measuring system. Than determination of the characteristics of test cell on cold (without the heating of air at entrance) regime and determination of the characteristics of test cell on regimes with the heating of air. Finally determination of tile characteristics of test cell with the loading of the working part by object. On tile final stage of gasdynamic adjustment two experiments with tile axisymmetric Scramjet model loaded into the working part of test cell were conducted. The first experiment was conducted with the purpose of determination of flow parameters with the object leaded into the working part and verification of experiment cyclogram. The second experiment was conducted with injection of hydrogen into the combustion chamber of object, that is tile conditions on test cell simulated Scramjet flight Mach number M = 6. Such methodology of gasdynamic adjustment allows to determine influence of experimental object on flow parameters in the working part at different conditions of experiment (with the burning in combustion chamber of object and without the homing), and also to compare flow characteristics in the object duct.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.1
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• pp.27-31
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• 2014

This paper describes a tomographic imaging technique for evaluating the thickness reduction of a plate-like structure using a noncontact sensor network based on an electromagnetic acoustic transducer that generates shear horizontal plate waves. Because this technique is based on the effect of mode cutoff and time of flight of guided waves caused by a change in thickness, the tomographic image provides information on the presence of defects in the structure. To verify the performance of the method, artificial defects with various thickness reduction ratios were machined in an aluminum plate, and the tomographic imaging results are reported. The results show that the generated tomographic image displays the thickness reductions and can identify their locations. Therefore, the proposed technique has good potential as a tool for health monitoring of the integrity of plate-like structures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.141-146
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• 2005

This paper presents a theoretical analysis of a ramjet and scramjet engine according to flight Mach numbers. The main objective of this study is to give physical understanding on the performance parameters and to provide a more unified treatment of the fundamentals of ramjet and scramjet propulsion, mainly based on analytical methods. The effects of flight Mach number, inlet characteristics, and combustion on the performance of ramjet and scramjet are analysed. The cycle analysis are conducted on both combustors with constant pressure and with constant cross-section area, on which comparisons are made. Also the optimal Mach number at the entry of the combustor is studied.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.709-716
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• 2011

The temperature of cryogenic propellant in the propellant tank increases during flight due to heat input from surroundings. The propellant which temperature rises up over the required condition of turbo-pump remains as unusable propellant at the end of flight. In this paper the estimation method of the heat transfer coefficient at the upper layer of cryogenic propellant was presented. The heat transfer mode at the propellant upper layer was considered as conduction. Temperature distributions near propellant surface obtained from heat transfer coefficient were compared with test data to show the possibility of this method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.203-206
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• 2006

We have studied, for maximizing the total impulse of liquid propulsion system, Propellant Utilization System (PUS) to minimize outage of propellant. Propellant outage is mainly influenced by propellant mixture ratio during flight and real quantity of loaded propellant. If one employs cryogenic propellant, the variation of propellant density due to the temperature change has major effect on outage control. Feedback control of propellant level of each tank during flight could deplete both tanks simultaneously. To introduce this system, however, the mixture ratio control system of rocket engine is necessary.