• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.2
• /
• pp.156-164
• /
• 2016

Qualification model(QM) of main payloads including concentrating photovoltaic system using fresnel lens, heating wire cutting type shockless holding and release mechanism, and MEMS-based solid propellant thruster have been developed for the STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project), which is a pico-class satellite for verification of core space technologies. In this study, we have verified structural safety and functionality of the developed payloads under a qualification temperature range through the QM thermal vacuum test. Additionally, a reliability of thermal model of the payloads has been confirmed by performing a thermal correlation based on the thermal balance test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.10
• /
• pp.833-839
• /
• 2013

Thermal vacuum test should be performed prior to launch to verify satellites' functionality in a harsh space environment which is represented by extremely cold temperatures and vacuum conditions. A thermal vacuum chamber which consists of a vacuum vessel, a pumping system, and a thermal control system are used to perform thermal vacuum tests of a satellite system and its components. A cryogenic blower is a core component of the closed loop thermal control system for thermal vacuum chambers. This paper describes the fan design of the cryogenic blower, the design of the thermal protection interface between the driving part and the fluid part, which were verified by thermal and structural analyses. The performance of the cryogenic blower is confirmed by similarity test on the test bench.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2009.04a
• /
• pp.265-266
• /
• 2009

구글 어스(Google Earth)란 도구는 인공위성에서 찍은 사진들을 바탕을 3차원 지구 타원체에 바탕에 입힌 도구이다. 이 도구는 3차원 공간에서 OpenAPI등을 이용하여 3차원객체를 지구 타원체상에 구현 할 수 있다. 이러한 점들 때문에 많은 사람들이 주요 건축물을 구현하거나 실외 이동객체(자동차, 비행기 등)를 구현하여 더욱더 지구와 가까운 모형으로 구현을 해 왔다. 하지만 공간 정보란 것은 실외 공간정보만이 아닌 건물의 내부 구조나 쇼핑몰상의 유동 인구의 움직임등과 같은 정보도 존재한다. 이 연구는 구글 어스 상에서 내부 구조를 가진 건물을 구축하고 이곳을 탐색할 수 있게 해 주며 또한 실내 이동 객체들의 실시간 움직임을 구현한다.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.2
• /
• pp.11-19
• /
• 1999

The design procedure as well as some test results of a low-cost commercial radome for mobile DBS(Direct Broadcasting Satellite) receiving antenna system are presented in this paper. At first the complex permittivity of dielectric material should be measured in order to select a material for radome design. The complex permittivities of low-cost plastics supplied by domestic vendors are measured and presented. And then the transmission losses of the sheets are calculated. The calculated results are verified by the measurements of wave transmission test of that sheets. Two kinds of radomes, ABS single-layer and A-Sandwich((PET-Foam-ABS), are fabricated and measured practically. The transmission losses of single-layer and A-sandwich radome are 1.5dB and 0.6dB respectively at the maximum wave incident angle of 57 degree. Also the calculated crosspolarization caused by A-sandwich radome is under 20dB.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.04a
• /
• pp.281-285
• /
• 2007

The flow characteristics in the thruster should be analyzed considering its geometry and the pressure ratio to estimate its performance and etc. This paper suggests the computational result of an axisymmetric real nozzle for the altitude control of a satellite to find out the application limit that the assumption of continuum mechanics holds. The steady non-reacted compressible flow field in the unstructured grid system is computed and analyzed with varying the environmental pressure (or the degree of vacuum) under the fixed pressure ratio in a real thruster of which the area ratio of exit to throat is 56. The assumption of the continuum mechanics is not approved when the environmental pressure is reduced less than $10^{-3}$ atm.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.6
• /
• pp.124-129
• /
• 2002

KAISTAT-4 is the fourth experimental microsatellite of KITSAT series which has been developed by Satellite Technology Research Center of KAIST for the last two years. The launch of KAISTSAT-4 is scheduled in 2003. The primary experimental payloads consist of Far-ultraviolet Imaging Spectrograph and Space Physis Package. In a similar way to KITSAT series, the interior of KAISTSAT-4 comprises mainly a set of stacked aluminium-alloy module boxes, each being capable of acting as the primary load path in the mechanical structure. The KAISTSAT-4 qualification model is now designed, fabricated, integrated, and tested to verify if the electrical and mechanical components work and can withstand the launch environments. All the required structural tests have been performed to a sufficient degree to satisfy the intent of the test requirements. This paper presents the structural system and launch environmental test results of KAISTSAT-4 qualification model.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.2
• /
• pp.155-166
• /
• 2021

In this paper, design study of a small two-stage launch vehicle is undertaken for the dedicated launch of the Compact Advanced Satellite 500 (CAS500)-class satellite into the Low Earth Orbit (LEO) by modifying the second and third stages of the Korean Space Launch Vehicle II (KSLV-II). Since the KSLV-II has three stages, velocity increment is newly distributed for the two-stage small launch vehicle. For this end, the staging design is carried out for the design parameters such as stage mass ratios, structural coefficients and engine options for each stage followed by trajectory analysis. Investigation of the results provides the combination of design parameters for the small launch vehicle for the dedicated launch of 500 kg-class satellite into LEO.

• Journal of Space Technology and Applications
• /
• v.1 no.3
• /
• pp.319-336
• /
• 2021

This paper discusses the results of launch environment tests for the engineering qualification model (EQM) of nanosatellite Scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) for scientific missions and lessons learned for the design of nanosatellites. SNIPE is a group of four formation-flying 6U nanosatellites with a range of payloads for missions including space weather measurement. We developed the EQM to verify the preliminary design prior to fabricating the flight model. Launch environment test of EQM was conducted for the first time in 2019, and all failures were corrected and verified at the second test conducted in 2021. A notable point of the two tests is that the nanosatellite deployer used in the first test is different from that of the second test. The second deployer has the capability to fix the internal satellite whereas the first deployer just contains and deploys the satellite. Thus actual mechanical loads the satellite receives is reduced for the second test compared to the first test. This work compares the mechanical responses of two tests and proposes general guidelines for structural design of nanosatellites.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.2
• /
• pp.75-82
• /
• 2003

이동체 탑재형 안테나는 설치 장소의 특성상 소형화와 경량화가 필수적인 요소이다. 그러므로 이동체 탑재형 안테나의 경우 반사판형 안테나보다 마이크로스트립 어레이 안테나가 널리 쓰이고 있다. 본 고에서는 마이크로 스트립 슬롯 어레이 안테나를 설계하였다. 만족스러운 고 이득을 얻을 수 있으며 동시에 패치 소자의 개수를 줄이기 위해 패치 단일 소자가 가급적 고 이득을 낼 수 있는 구조로 설계하였다. 본 고에서 설계한 슬롯 안테나는 기생슬롯을 가진 H 자형 타입의 소자이다. 설계는 제작상의 오차를 고려하여, 운용 주파수 11.7~12.75 GHz에서 VSWR 1.8:1 이하를 목표로 하였다. 제작된 안테나의 측정결과는 11.7~12.75 GHz대역에 걸쳐 VSWR < 1.8의 만족한 결과를 보이고, 단일 소자의 시뮬레이션 이득 결과는 10 dBi를 보였으며 $4\times4$ 어레이를 했을 경우 이득은 22 dBi의 값을 보였다. 제작되어진 안테나는 추후 급전 네트웍의 최적화를 통해 상호 간섭(Mutual Coupling)을 최소화하여 효율을 최대화한다면 직접 위성 서비스를 수신하기 위한 초소형 안테나로 활용될 수 있을 것으로 기대된다.

• 한국정보통신설비학회:학술대회논문집
• /
• 2003.08a
• /
• pp.12-15
• /
• 2003

이동체 탑재형 안테나는 특성상 소형화 및 신호 추적 시간 단축이 중요한 요소이다. 이러한 특성은 위상변위기를 이용한 전자적인 빔 조향 방식으로 한층 더 보완할 수 있다. 현재 이동체에서 주로 사용되고 있는 DBS (Direct Broadcasting Satellite) 수신용 안테나는 패치 및 슬롯 형태의 안테나 소자를 배열하여 사용한다. 하지만 이러한 안테나 소자는 전방위각에 대해 인공위성 방향(앙각 45도)에서 이득 손실이 있기 때문에 위상변위기를 이용한 빔 조향 방식에서 사용하기에는 문제점을 가지고 있다. 따라서 모든 방위각에 대해 앙각 45도에서 최대 이득 특성을 갖는 안테나 소자를 이용해 이득 손실을 줄이는 것은 큰 의미가 있다. 본 논문에서는 monopole 주변에 PBG(Photonic Band Gap) 구조를 구현함으로써 표면파를 억제하여 앙각 45도 방향에서 최대 이득 특성을 보이는 안테나 소자를 제안한다.