• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.50.1-50.1
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• 2014

The Multi-purpose InfraRed Imaging System (MIRIS) is the main payload of Science and Technology Satellite 3 (STSAT-3), which was launched onboard Dnepr rocket from Russian Yasny Launch Base in November 2013. The MIRIS is an infrared (IR) camera, and the telescope has to be cooled down to below 200K in order to reduce thermal background noise. For the effective cooling and low-power consumption, we applied passive cooling method to the thermal design of the MIRIS. We also conducted thermal analysis and tested for the passive cooling before the launch of STSAT-3. After the launch, we have received State-of-Health (SOH) data from the satellite on orbit, including temperature monitoring results. It is important that the temperature of the telescope was shown to be cooled down to below 200K. In this paper, we present both the temperature data of the MIRIS on orbit and the thermal analysis results in the laboratory. We also compare these results and discuss the verification of the passive cooling.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.208.2-208.2
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• 2012

The Slewing Mirror Telescope (SMT) is a key telescope of Ultra-Fast Flash Observatory (UFFO) space project to explore the first sub-minute or sub-seconds early photons from the Gamma Ray Bursts (GRBs) afterglows. The first realization of UFFO is the 20kg UFFO-Pathfinder (UFFO-P) to be launched on board the Russian Lomonosov satellite in 2013 by the Soyuz-2 rocket. Once the UFFO Burst Alert & Trigger Telescope (UBAT) detects the GRBs, Slewing mirror (SM) will rotate to bring the GRB into the SMT's field of view instead of slewing the entire spacecraft. SMT can image the UV/Optical counterpart with about 4-arcsec accuracy. However it will provide a important understanding of the GRB mechanism by measuring the sub-minute optical photons from GRBs. SMT can respond to the trigger over $35^{\circ}{\times}35^{\circ}$ wide field of view within 1 sec by using Slewing Mirror Stage (SMS). SMT has 10-cm Ritchey-Chretien telescope and $256{\times}256$ pixilated Intensified Charge-Coupled Device (ICCD) on focal plane. In this paper, we discuss the overall design of UFFO-P SMT instrument and payloads development status.

• Journal of Korea Technology Innovation Society
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• v.15 no.1
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• pp.163-184
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• 2012

Although there are some technical reports on the example of Korea's first rocket, the Naro, there has been no studies on why there were two technical incidences in the space development programs which massive amount of physical and human resources were invested. For this, the objective of this study is to investigate the example of the Naro from the aspect of management and institutions as well as technical in terms of the responsibility of the R&D organization. Most important part in the responsibility of the R&D organization is the professional responsibility and it is difficult to attain the goals when they are diluted by political situations. Furthermore, this study also looked at the cause of the failure to exert righteous sovereign authority in the conflict with Russia from the discrepancy of goals between the authority and the agent, and studied efforts to prevent the recurrence of discrepancy.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.330-339
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• 2008

Ground-based interceptors(GBI) comprise a major element of the strategic defense against hostile targets like Intercontinental Ballistic Missiles(ICBM) and reentry vehicles(RV) dispersed from them. An optimum design of the subsystems is required to increase the performance and reliability of these GBI. Propulsion subsystem design and optimization is the motivation for this effort. This paper describes an effort in which an entire GBI missile system, including a multi-stage solid rocket booster, is considered simultaneously in a Genetic Algorithm(GA) performance optimization process. Single goal, constrained optimization is performed. For specified payload and miss distance, time of flight, the most important component in the optimization process is the booster, for its takeoff weight, time of flight, or a combination of the two. The GBI is assumed to be a multistage missile that uses target location data provided by two ground based RF radar sensors and two low earth orbit(LEO) IR sensors. 3Dimensional model is developed for a multistage target with a boost phase acceleration profile that depends on total mass, propellant mass and the specific impulse in the gravity field. The monostatic radar cross section (RCS) data of a three stage ICBM is used. For preliminary design, GBI is assumed to have a fixed initial position from the target launch point and zero launch delay. GBI carries the Kill Vehicle(KV) to an optimal position in space to allow it to complete the intercept. The objective is to design and optimize the propulsion system for the GBI that will fulfill mission requirements and objectives. The KV weight and volume requirements are specified in the problem definition before the optimization is computed. We have considered only continuous design variables, while considering discrete variables as input. Though the number of stages should also be one of the design variables, however, in this paper it is fixed as three. The elite solution from GA is passed on to(Sequential Quadratic Programming) SQP as near optimal guess. The SQP then performs local convergence to identify the minimum mass of the GBI. The performance of the three staged GBI is validated using a ballistic missile intercept scenario modeled in Matlab/SIMULINK.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.125-130
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• 2018

The technology development of a high performance upper stage engine for a GEO(GEostationary Orbit) KSLV(Korea Space Launch Vehicle) is undergoing in Korea Aerospace Research Institute. KSLV is composed of an open cycle engine with gas generator, which is for a low orbit launch vehicle. However the future GEO launch vehicle requires a high performance upper stage engine with a high specific impulse. The staged combustion cycle engine is necessary for this mission. In this paper, current progress and future plan for staged combustion cycle engine development is described.

• Journal of the Korean Geosynthetics Society
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• v.21 no.3
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• pp.29-39
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• 2022

The engineering characteristics of synthetic polymer-silica sol, which has the effect of reducing leakage, was evaluate and compared with typical grouting material, the water glass-based SGR injection material in this study. The result of the laboratory tests on strength and durability about the synthetic polymer-silica sol showed more than twice as high as LW-based injection materials in uniaxial compressive strength, significantly lower values in shrinkage rate and permeability. The result of pH was less than 8.5 (the drinking water quality standard). As a result of the leaching test, the Na₂O elution amount of the synthetic polymer-silica sol was measured to be 3 to 4 times smaller than that of the water glass grout. These results be assumed that the synthetic polymer-silica sol has better durability and permeability than those of the typical water glass-based grout.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1062-1070
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• 2015

This paper presents an application of an optimal smoothing filter for moving target tracking problem based on measured noise source. In order to measure distance and velocity for the moving target, a beamforming method is applied to use the noise source by using microphone array. Also a Kalman filter and an optimal smoothing algorithm are adopted to improve accuracy of trajectory estimation by using a Singer target model. The simulation is conducted with a missile dynamics to verify performance of the optimal smoothing filter, and a model rocket is used for experiment environment to compare the trajectory estimation results between the beamforming, the Kalman filter, and the smoother. The Kalman filter results show better tracking performance than the beamforming technique, and the estimation results of the optimal smoother outperform the Kalman filter in terms of trajectory accuracy in the experiment results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.9
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• pp.731-743
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• 2020

The hypersonic glide vehicle ascends to a high altitude by a rocket booster, separates it from the booster, and glides at a hypersonic speed of Mach 5 or higher at an altitude of about 30~70 km, changing its direction in the atmosphere. Since it moves on an unpredictable flight path rather than a parabolic trajectory, it is difficult to intercept with current missile defense systems. The U.S. conducted HTV-2 and AHW flight tests in the early 2010s to confirm the possibility of hypersonic gliding flights, and recently it has been developing hypersonic glide vehicle systems such as LRHW and ARRW. China has conducted several flight tests of the DF-ZF (WU-14) glide vehicle since 2014 and has been operating it with DF-17 missiles. Russia has conducted hypersonic glide vehicle research since the former Soviet Union, but it has repeatedly failed, and recently it has been successfully tested with the Avangard (Yu-71) glide vehicle mounted on the SS-19 ICBM. In this paper, the characteristics, flight test cases, and development trends of hypersonic glide vehicles developed or currently being developed in the United States, China, Russia, Japan, India, and Europe are reviewed and summarized.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.120-125
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• 2002

In the preceding tests using the KSR-III Sub.(I) engines, it was observed that the heat resistant capability of the engines was not enough for the mission. So Sub.(I) Mod. engines were designed and tested. The Sub.(I) Mod. engines have three major design parameters - the arrangement of main injectors, the impinging angle of main injectors and thermal barrier coating. More than twenty experiments were carried on to evaluate engine performance and heat resistance capability with respect to design parameters. In this study, the test results are introduced. Analysing the result of Sub.(I) engine tests, it is found that decreasing the impinging angle, adopting the H-type arrangement(rather than radial type arrangement) and adopting the thermal barrier coating can increase heat resistance capacity substantially. Also, engine performance evaluation is conducted using specific impulse and characteristic velocity parameter. The results show that the performance variation is small(about 5%) and the performance is better in the case of radial arrangement. It is suspected that these phenomena are caused by the change of flame structure atomization mixing characteristic of sprays and the distortion of recirculation zone. Also from the low frequency instability point of view, it is observed that reducing the impinging angle and adopting the H type arrangement can increase the instability characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.671-680
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• 2021

This paper deals with the contents of designing and producing reconnaissance hardware and software, and verifying the functions after being installed on the CanSat platform and ground stations. The main reconnaissance mission is largely composed of two things: terrain search that renders the surrounding terrain in 3D using radar, GPS, and IMU sensors, and real-time detection of major objects through optical camera image analysis. In addition, data analysis efficiency was improved through GUI software to enhance the completeness of the CanSat system. Specifically, software that can check terrain information and object detection information in real time at the ground station was produced, and mission failure was prevented through abnormal packet exception processing and system initialization functions. Communication through LTE and AWS server was used as the main channel, and ZigBee was used as the auxiliary channel. The completed CanSat was tested for air fall using a rocket launch method and a drone mount method. In experimental results, the terrain search and object detection performance was excellent, and all the results were processed in real-time and then successfully displayed on the ground station software.