• 항공우주정책ㆍ법학회지
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• 제26권1호
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• pp.177-213
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• 2011

현재 우주활동에 의하여 발생된 손해에 대한 배상책임과 관련된 국제조약으로 1967년 우주조약과 1972년 우주손해배상책임조약이 있으며, 또한 우리나라 국내법으로 2008년 우주손해배상법이 있다. 우주조약은 우주활동에 대한 국가의 국제적 책임과 우주물체에 의한 손해에 대한 국가의 불법행위 책임에 관하여 규정하고 있다. 우주손해책임조약은 발사국의 절대적 책임, 과실책임, 연대책임, 배상청구권자, 배상청구방법, 배상청구기한, 배상청구와 국내적 구제, 손해배상액, 청구위원회 설치 등에 관하여 규정하고 있다. 우리나라 우주손해배상법은 우주손해의 정의, 우주손해책임조약과의 관계, 발사자의 무과실책임 및 책임의 집중, 발사자의 손해배상책임한도액, 발사자의 책임보험 가입, 정부의 피해자 구조 및 발사자 지원 등에 관하여 규정하고 있다. 우주사고로 인한 손해배상책임 관련 사례들로 Iridium33과 Cosmos 2251 위성충돌 사건, Cosmos 954 위성추락 사건, Martin Marietta의 위성발사 실패 사건, Westar VI 위성 작동불량 사고 등이 있으며, 이러한 우주사건에 관한 분쟁 또는 소송에 있어서 위성의 발사국, 발사자 및 제조자의 손해배상책임 부담문제에 관련하여 절대책임(엄격책임)원칙 또는 과실책임원칙이 적용되어 해결되고 있다. 우주손해책임조약의 개선방안으로 손해배상청구권자의 명확한 규정, 청구위원회의 결정의 구속력 확보 등을 들 수 있고, 우리나라 우주손해배상법의 개선방안으로 손해배상범위에 간접손해 포함, 손해배상책임 한도액의 통화단위 변경, 공동발사자의 연대책임 및 구상권 신설, 우주손해배상심의위원회의 설치 등을 들 수 있다. 우리나라는 2009년 6월 전남 고흥군 외나로도에 우주센터가 준공되어 동년 8월 및 2010년 6월 우리나라 최초 소형 우주발사체 나로호(KSLV-1)를 두차례 발사하였다. 향후 우리나라는 우주활동 과정에서 우주관련 국제조약 및 국내법상의 국제적 책임 및 우주손해에 대한 배상책임 등 문제들이 발생할 가능성이 있으므로 우리정부 및 우주물체 발사기관은 이러한 문제들에 대한 법적 제도적 대응책을 마련해야 할 것이다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.