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Solar Sails: Technology And Demonstration Status
Johnson, Les,Young, Roy,Barnes, Nathan,Friedman, Louis,Lappas, Vaios,McInnes, Colin The Korean Society for Aeronautical and Space Scie 2012 International Journal of Aeronautical and Space Sc Vol.13 No.4
Solar Sail propulsion has been validated in space (IKAROS, 2010) and soon several more solar-sail propelled spacecraft will be flown. Using sunlight for spacecraft propulsion is not a new idea. First proposed by Frederick Tsander and Konstantin Tsiolkovsky in the 1920's, NASA's Echo 1 balloon, launched in 1960, was the first spacecraft for which the effects of solar photon pressure were measured. Solar sails reflect sunlight to achieve thrust, thus eliminating the need for costly and often very-heavy fuel. Such "propellantless" propulsion will enable whole new classes of space science and exploration missions previously not considered possible due to the propulsive-intense maneuvers and operations required.
Les Johnson,Roy Young,Nathan Barnes,Louis Friedman,Vaios Lappas,Colin McInnes 한국항공우주학회 2012 International Journal of Aeronautical and Space Sc Vol.13 No.4
Solar Sail propulsion has been validated in space (IKAROS, 2010) and soon several more solar-sail propelled spacecraft will be flown. Using sunlight for spacecraft propulsion is not a new idea. First proposed by Frederick Tsander and Konstantin Tsiolkovsky in the 1920’s, NASA’s Echo 1 balloon, launched in 1960, was the first spacecraft for which the effects of solar photon pressure were measured. Solar sails reflect sunlight to achieve thrust, thus eliminating the need for costly and often very-heavy fuel. Such “propellantless” propulsion will enable whole new classes of space science and exploration missions previously not considered possible due to the propulsive-intense maneuvers and operations required.
Mohan Hingorani,Sanjay Dixit,Miriam Johnson,Victoria Plested,Kevin Alty,Peter Colley,Andrew W. Beavis,Rajarshi Roy,Anthony Maraveyas 대한암학회 2015 Cancer Research and Treatment Vol.47 No.4
Purpose We report the outcomes of patients treated with palliative radiotherapy (pRT) to the primarytumour in the context of well-controlled metastatic disease after initial chemotherapy. Materials and MethodsClinical records of 132 patients with metastatic esophago-gastric (OG) cancer treated withpalliative chemotherapy (pCT) between January 2009 and June 2013 were reviewed. Ninetysevenpatients had responding or stable disease after 3 months of chemotherapy, of whom53 patients received pRT to the primary tumour after initial chemotherapy in the presenceof well-controlled metastatic disease (group A, pCT-RT). The remaining 44 patients weretreated with pCT alone (group B, pCT). Treatment-related outcomes were assessed in abovegroups including time to local progression (TTLP), progression-free and overall survival. ResultsThe median overall survival for patients treated with pRT after initial chemotherapy (groupA) was 23.3 months (95% confidence interval [CI], 17.70 to 28.89 months) and significantlyhigher than the 14 months (95% CI, 10.91 to 17.08 months) in patients treated with pCTalone (group B) (p < 0.001). The use of pCT-RT was an independent predictor of OS in multivariateanalysis. Local recurrence was observed in 12/53 of patients (23%) in group Acompared to 16/44 (36%) in group B. The median TTLP was significantly higher in patientsafter pCT-RT at 17.3 months (5.23 months to 44.50 months) compared to 8.3 months(range, 4.10 to 25.23 months) in patients treated with pCT alone (p=0.006). ConclusionThe possibility of pRT influencing systemic disease in advanced OG cancer has not beenreported, and results from the present study present strong arguments for investigation ofthis therapeutic strategy in a randomized trial.
Binder burnout and sintering kinetic study of alumina ceramics shaped using methylcellulose
K. Rajeswari,S. Chaitanya,P. Biswas,M. Buchi Suresh,Y.S. Rao,Roy Johnson 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1
Ceramic components are generally processed by the techniques such as compaction, extrusion, injection molding, casting etc., and the selection of forming method is generally based on the complexity of the shapes. Additives such as binders, plasticizers, surfactants and lubricants, which are generally organic in nature, play a significant role to ensure the flowability of the mass which is critical in shaping of ceramics. Alumina (α-Al2O3) powder was subjected to torque rheometric studies to identify Critical Volume Binder Concentrations (CBVC) corresponding to specific processing regimes. An initial torque value of 3-4Nm for compaction followed by 6-7N-m for extrusion and 2-3N-m for casting regimes were observed. Viscosities of the pre-mixes prepared by the addition of methyl cellulose (C6H7O2 (OH)x(OCH3)y, (where x = 1.0-1.5 and y = 2-1.45) as a binder were also found to exhibit a similar trend in viscosity, corresponding to CBVC torque values and are shaped into green specimens. Green strength of the standard specimens (45 × 4 × 3 mm) was estimated through 3-point bend tests and exhibited a good correlation with the binder content. Binder burnout characteristics were also elucidated by TG/DSC technique and activation energy estimated is 75-110 kJ/mol for the thermal degradation of methylcellulose binder. Activation energy of 883 ± 45 kJ/mol was estimated through kinetic analysis of sintering by the construction of the Master Sintering Curves (MSC).