• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.69-72
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• 2008

Decay processes of accumulated charge in e-beam irradiated polymers during elevating temperature are observed using pulsed electro-acoustic measurement system. Since the polymeric materials have many superior properties such as light-weight, good mechanical strength, high flexibility and low cost, they are inevitable materials for spacecrafts. In space environment, however, the polymers sometimes have serious damage by irradiation of high energy charged particles. When the polymers of the spacecraft are irradiated by high energy charged particles, some of injected charges accumulate and remain for long time in the bulk of the polymers. Since the bulk charges sometimes cause the degradation or breakdown of the materials, the investigation of the charging and the decay processes in polymeric materials under change of temperature is important to decide an adequate material for the spacecrafts. By measuring the charge behavior in e-beam irradiated polymer, such as polyimide or polystyrene, it is found that the various accumulation and decay patterns are observed in each material. The results seem to be useful and be helpful to progress in the reliability of the polymers for the spacecraft.

• 한국항공우주학회지
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• 제40권1호
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• pp.86-92
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• 2012

인공위성 자세제어에 널리 사용되는 구동기는 추력기, 반작용휠, 제어 모멘트 자이로(CMG), 그리고 자장토커 등이 있다. 그 중에서 CMG는 물리학의 자이로스코프 원리에 의한 토크를 발생시키는 구동기로서 적은 소모 전력으로 큰 토크를 출력하는 장점을 가지고 있다. 본 논문에서는 CMG 하드웨어 기술의 개요와 위성분야 적용 사례 및 관련된 하드웨어의 특성을 소개하며 더불어 선박, 로봇, MEMS 등 타 분야의 활용사례와 연구동향을 제공한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.329-330
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• 2007

Decay processes of accumulated charge in e-beam irradiated polymers during elevating temperature are observed using pulsed electro-acoustic measurement system. Since the polymeric materials have many superior properties such as light-weight, good mechanical strength, high flexibility and low cost, they are inevitable materials for spacecrafts. In space environment, however, the polymers sometimes have serious damage by irradiation of high energy charged particles. When the polymers of the spacecraft are irradiated by high energy charged particles, some of injected charges accumulate and remain for long time in the bulk of the polymers. Since the bulk charges sometimes cause the degradation or breakdown of the materials, the investigation of the charging and the decay processes in polymeric materials under change of temperature is important to decide an adequate material for the spacecrafts. By measuring the charge behavior in e-beam irradiated polymer, such as polyimide or polystyrene, it is found that the various accumulation and decay patterns are observed in each material. The results seem to be useful and be helpful to progress in the reliability of the polymers for the spacecraft.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1992-1993
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• 2007

Decay processes of accumulated charge in e-beam irradiated polymers during elevating temperature are observed using pulsed electro-acoustic measurement system. Since the polymeric materials have many superior properties such as light-weight, good mechanical strength, high flexibility and low cost, they are inevitable materials for spacecrafts. In space environment, however, the polymers sometimes have serious damage by irradiation of high energy charged particles. When the polymers of the spacecraft are irradiated by high energy charged particles, some of injected charges accumulate and remain for long time in the bulk of the polymers. Since the bulk charges sometimes cause the degradation or breakdown of the materials, the investigation of the charging and the decay processes in polymeric materials under change of temperature is important to decide an adequate material for the spacecrafts. By measuring the charge behavior in e-beam irradiated polymer, such as polyimide or polystyrene, it is found that the various accumulation and decay patterns are observed in each material. The results seem to be useful and be helpful to progress in the reliability of the polymers for the spacecraft.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권1호
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• pp.66-66
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• 2004

Observability of two spacecraft system is considered with relative line-of-sight vector measurements between two spacecraft system for autonomous navigation using the linear observability analysis. First, the dynamical equations and measurement models are introduced, and the basic assumption of attitude knowledge for one of two spacecrafts is explained. Then, we introduce a pair of nominal orbits of two spacecraft system, and the observability analysis for the nominal orbits is presented with the available measurements (for the numerical observability analysis). (omitted)

• 항공우주기술
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• 제13권2호
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• pp.167-176
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• 2014

유로의 개폐를 위해 사용되는 파이로밸브는 가볍고 신뢰성이 높은 장점을 가진다. 미국에서는 하이드라진 추진제를 사용하는 일부 위성 유실의 원인을 착화기 연소 가스의 누설로 판단하였고, 블로우바이라 불리는 이러한 누설 문제를 방지하기 위하여 억지끼워맞춤을 하는 피스톤을 개발하고 추가적인 설계변경을 통하여 신뢰성을 향상하였다. 여기서는 미국에서 수행된 파이로밸브 연구에 대한 문헌조사를 AIAA Paper 위주로 수행하였다. 또한 파이로밸브의 일반적인 문제점과 개선방향, 성능비교평가 사례 등을 다루었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.149-149
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• 2003

This paper presents the work peformed in a program developing composite material which properties satisfy structural and thermal requirements for aircrafts and spacecrafts. In the aerospace vehicle structures, the specific strength of the materials is one of the important requirements and this is why polymer matrix composite material with reinforced carbon fiber is widely used. However, the mechanical properties of the composite material have been known to be dependent on processing and this difficulties in evaluation have caused a lot of mechanical tests for each batch.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.62-66
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• 2008

Spacecrafts such as most of commercial satellites that are operating in the geostationary orbit can be subjected to intense irradiation by charged particles. The surface made of dielectric materials can therefore become probable sites for damaging electrostatic discharges. Thanks to a specially equipped chamber, the spatial environment can be reproduced experimentally in the laboratory. In this paper, the behavior of high energy electrons injected in polymers such as PolyMethylMetaAcrylate (PMMA) and Kapton is studied. Results obtained by surface potential technique, pulse-electro acoustic device and a cell based on the split Faraday cup system are analyzed and discussed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.241-245
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• 2005

Strapdown inertial navigation system (SINS) integrated with astronavigation system (ANS) yields reliable mission capability and enhanced navigational accuracy for spacecrafts. The theory and characteristics of integrated system based on unscented Kalman filtering is investigated in this paper. This Kalman filter structure uses unscented transform to approximate the result of applying a specified nonlinear transformation to a given mean and covariance estimate. The filter implementation subsumed here is in a direct feedback mode. Axes misalignment angles of the SINS are observation to the filter. A simple approach for simulation of axes misalignment using stars observation is presented. The SINS error model required for the filtering algorithm is derived in space-stabilized mechanization. Simulation results of the integrated navigation system using a medium accuracy SINS demonstrates the validity of this method on improving the navigation system accuracy with the estimation and compensation for gyros drift, and the position and velocity errors that occur due to the axes misalignments.

• 전자공학회논문지B
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• 제32B권6호
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• pp.932-942
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• 1995

A spacecraft power system can be divided into two types : DET system(Direct Energy Transfer system) and PPT system(Peak Power Tracking system). In a DET system employing the regulated bus voltage control method, the battery charger and discharger are widely used for the bus voltage regulation. The battery charger has two different modes of operation. One is the bus voltage regulation mode and the other is the charge current regulation mode. The battery discharger is employed to provide the power when the spacecraft is in the earth's shadow or the sun is eclipsed. The operating mode, charging or discharging, is selected by a power control circuit. In this paper, small-signal dynamic characteristics of battery charging and discharging system are analyzed to facilitate design of control loop for optimum performance. Control loop designs in various operating modes are discussed. Anaylses are verified through experiments.