• 한국안광학회지
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• 제21권3호
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• pp.191-201
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• 2016

목적: 성분 조성이 다른 인공눈물들이 소프트콘택트렌즈를 착용한 건성안의 착용 초기 눈물막 안정성 및 자각증상에 미치는 영향을 알아보았다. 방법: Etafilcon A 재질의 소프트콘택트렌즈를 착용한 50안의 건성안에 성분 조성이 다른 3종의 인공눈물 용액 및 식염수를 각각 점안하고 비침습성 눈물막 파괴시간(NIBUT)를 인공눈물 점안한 직후부터 30분까지 5분 간격으로 측정하였고, 점안 30분후의 순목 횟수 및 자각증상 변화를 알아보았다. 결과: 3종의 인공눈물 모두 식염수보다 NIBUT를 더 크게 증가시켰다. 인공눈물 점안 직후의 NIBUT 증가 효과는 점성조절제가 포함된 인공눈물에서 가장 컸으며, 효과지속 시간은 계면활성제와 점성조절제가 모두 포함된 인공눈물이 가장 길었다. 순목 횟수는 인공눈물 용액과 식염수 점안시 모두 통계적으로 유의한 변화가 없었다. 자각적 증상은 인공눈물 및 식염수 점안으로 모두 통계적으로 유의하게 향상되었으며 대부분의 용액에 의해 건조감, 이물감, 피곤감, 뻑뻑함, 눈시림 증상의 향상이 나타났다. 점안 30분 후에는 인공눈물 점안전의 자각증상과 유사한 수준으로 복귀하였다. 결론: 건성안의 소프트콘택트렌즈 착용 초기 자각 증상은 인공눈물과 식염수 모두 완화시켜주지만 눈물막의 안정성에 미치는 효과는 함유 성분에 따라 차이가 있음을 밝혔다. 본 연구결과를 통하여 콘택트렌즈 착용 건성안의 착용 초기 안구건조증 개선을 위해서는 적절한 인공눈물의 선택이 필요함을 제안한다.

• 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.