• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.914-921
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• 2017

The experimental research on a high-altitude environment simulation of space launch vehicle is important for securing independent technologies with launching space vehicles and completing missions. This study selected an altitude of 65 km for the experiment environment where it exceeded Mach number of 6 after the launch of Korean Space Launch Vehicle(KSLV-II). Shock tunnel was used to replicate the flight condition. After flow establishment, in order to confirm aerodynamic characteristics and normal and oblique shockwaves, the flow verification was carried out by measuring stagnation pressure and heat flux of a forebody model, and shockwave stand-off distance of a hemispherical model. In addition, a shock-free technique to recover free-stream condition has been developed and verified. From the results of the three verification tests, it was confirmed that the flow was replicated with the error of about ${\pm}3%$. The error between the slope angle of inclined shockwave of the scaled down transition section model using the shock-free shape and the slope angle of the horizontal plate model, and between the theoretical and the experimental value of the static pressure of the model were confirmed to be 2% and 1%, respectively. As a result, the efficiency of the shockwave cancellation technique has been verified.

• Journal of Space Technology and Applications
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• v.2 no.1
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• pp.52-65
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• 2022

Korea is near close the success on the indigenous launch vehicle KSLV-2 after the second test launch during the second half of 2022, and the satellite development has been already in the level of advanced country. After the such mature of satellite and launch vehicle technologies, Korea's space development main theme should be 'Space Exploration and Space Application', and paradigm should be changed from 'Hardware' to 'Scientific/Technological Mission', from 'Unmanned' to 'Manned'. Korea's prime space strategy should be the direction of expansion of space industry, creation of employment and secure the key technologies, improvement of convenience and safety of people. For the purpose it is necessary to start 'Manned Space Development' such that participation to 'Artemis and Gateway Program' in 20s' and manned Mars exploration in 30s' which would be carried out by means of global international cooperation, and which could be a good opportunity to explore the new area of space development and upgrade national technology capability. Taking advantage of this opportunity, it is required for Korea to join the international programs through developing indigenous challenging, sustainable Korean mission and hardware. Also selection of the 2^nd Korean Astronaut could draw national attention, especially could give dreams to young generation. Participation to the Artemis program could be the opportunity of entering the major space fairing nation and boosting up national pride. In this study we survey and analyze the Artemis Program in detail, and in conclusion we suggest the strategy of Korea's participation to the Artemis Program.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.96-102
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• 2012

Recently, interests about frame error reduction method, using multiple PCM data which are received at several ground stations, are increasing. Simple data merge method is already applied to data processing system at Naro Space Center and have been used in the first and the second flight test analysis of KSLV-I. This paper is focused on error reduction with error correcting merge algorithm and time-delayed data correction algorithm. Result of applying the proposed algorithms to the flight test data shows 1.32% improvement in error rate, compared to simple-data-merge method. It is considered that presented algorithms could be very useful in generating various telemetry merge data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.1
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• pp.69-77
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• 2012

After lunar explorations were restarted in 1990s, the world space advanced countries have been competing actively to preoccupy the Moon from the 2000s. Korea has been also conducting precedent study on lunar exploration to carry out that by ourselves in 2020. This study analyzed delta-V of various Earth-Moon transfer trajectories for minimization of fuel consumption. Through the simulation, the best Earth-Moon transfer trajectory for Korean lunar mission is suggested and it will be used as useful materials of Korean lunar mission.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.185-188
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• 2008

This paper introduces the Bootstrap method for statistical analysis of noise and vibration spectrum in aeronautic and space fields. Generally, all components of a launch vehicle and its payloads are subjected to high intensive noise and vibration environment during the lift-off phase and the ascent phase through Mach =1 and Max Q. In order to verify their survivabilities against these severe vibroacoustic environments during qualification tests and acceptance tests, it is most important to estimate the proper upper limits of the environmental condition. Although NASA has typically utilized the Normal Tolerance Limit method in deriving these levels, the reference[1] says that the Bootstrap can be also an alternative method to estimate the maximum expected environments. In this paper, a general procedure of the Bootstrap method is summarized, and it is applied to analyze acceleration power spectral density functions, which were measured during acoustic test on the upper stage of KSLV-I.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.162.2-162.2
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• 2012

한국형 발사체 KSLV-2의 발사능력을 고려하면 달 탐사선의 총 무게는 약 550kg이 된다. 따라서 달 탐사선에 탑재할 수 있는 탑재체 무게를 최대화하기 위해서는 지구에서 달로 가는 천이궤적을 가장 효율적으로 설계하여 연료 소모량을 최소화하여야 한다. 본 연구에서는 최근에 달 탐사 천이궤적으로 가장 많이 사용되고 있는 Weak Stability Boundary 천이궤적에 관해 연구를 수행하였다. Weak Stability Boundary 천이궤적은 지구로부터 출발한 후 원지점 약 1.4 km(지구-태양의 L1 점 근처)까지 비행한 후 태양풍을 통해 에너지를 얻어 근지점 거리를 지구-달 거리만큼 증가시켜 LOI(Lunar Orbit Injection)시 ${\Delta}V$를 최소화하여 달 궤도에 들어가는 방법이다. Weak Stability Boundary 천이방법의 TLI(Trans Lunar Injection) 값은 직접천이 방법의 TLI 값보다 더 크지만 달 궤도 진입에 필요한 LOI ${\Delta}V$값은 25% 정도 덜 든다는 장점이 있다. 이 방법은 일본의 Hiten 탐사선이 최초로 사용하였으며, 달에 도착하기까지 수개월이 걸리는 단점이 있다. Weak Stability Boundary 천이궤적 시뮬레이션을 통해 최대로 절약할 수 있는 연료 소모량을 확인할 수 있었으며, 다른 천이방법들과의 장단점 비교를 통해 한국형 달 탐사선의 지구-달 천이궤적 후보로 사용 될 수 있음을 확인하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1144-1147
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• 2017

It was reviewed about the pressure oscillation on the inlet of turbo-pump at the moment of engine startup and shutdown. Specially, This research was performed how much is the effect of PSD(Pogo Suppression Device) about the pressure oscillation on the inlet of turbo-pump at the moment of engine startup and shutdown. For analysis, propellant tank PSD and Engine are modelled with Flowmaster which is the commercial 1D program. As the analysis results, even though the PSD is installed in the pipeline, the pressure drop or rising at the moment of engine startup and shutdown is same compared to the case without PSD. However, it was confirmed that PSD reduces the pressure oscillation of the high frequency band as the original purpose of PSD.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.181-188
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• 2016

It is known that reliability of liquid rocket engines depends on the design thrust, propellant, engine cycle, and hot firing test time. Previously, a method was developed for estimating reliability of a new engine by adjusting the design thrust and hot firing test time of reference engines where reference engines have the same propellant and engine cycle with the new engine. In this paper, we provide a procedure to predict the engine reliability when the new engine and the reference engine have different propellant and engine cycles. The proposed method is illustrated to estimate the engine reliability of the first stage of Korea Space Launch Vehicle II.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.78-84
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• 2011

CFD simulation has been conducted on a small scaled 4 nozzle clustered engine operating with air. In the present paper, the effects of grid size, turbulence models, flux difference methods have been compared. The results show that the base flows are somewhat different as the turbulence models, while Roe and AUSM flux differences produced almost the same results. Spalart-Allmaras turbulence model produces more accurate results rather than famous SST k-w model. The calculated Mach number and pressure profile in the engine base reveal the complex base flow structure, which is somewhat different from the generally estimated flow fields.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.440-443
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• 2008

Plume radiation has been measured during ground tests of KSLV-I kick motor in order to predict the thermal load on the equipment around the kick motor at flight. The measuring positions are the kick motor base, and the measured heats were about 2${\sim}$5 w/cm$^2$. The measured heat showed a lot of shot fluctuation in their values, and the radiative heats at the latter half of time are higher than those of the first half. A plausible explanation for these phenomena was given as the variation of alumina particles with time. The radiative heats along the plume axis were also measured recently at 8 positions with 1.5m radius from plume axis, but only the initial parts of the results could be acceptable because the sensor were damaged by the accumulated heat. The strongest heat occurred at the middle of the plume, which can be explained with different view factors. Despite of the plausible explanation, it seems to need more analysis because the plume structure such as temperature, alumina particle, after burning has not been revealed until yet. The measure heat flux has been reflected in the prediction of the plume radiation at high altitude where the kick motor operates.