• 제목/요약/키워드: HyFly

검색결과 7건 처리시간 0.018초

미 공군의 이중모드 램제트 (DMR) 및 미 해군의 이중연소 램제트 (DCR) 개발 동향 (Research Activities of Dual-Mode Ramjet (DMR) by USAF and Dual-Combustion Ramjet (DCR) by US Navy)

  • 최정열;노진현;원수희;신재렬
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2009년도 춘계학술대회 논문집
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    • pp.400-401
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    • 2009
  • 본 논문에서는 DARPA의 지원하에 미공군이 이중모드 램제트를 이용하여 개발하고 있는 X-51A와 미 해군이 이중연소 램제트를 이용하여 개발하고 있는 HyFly 의 개념 및 연구 개발 활동에 대하여 소개한다.

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Experimental Investigation on Post-Fire Performances of Fly Ash Concrete Filled Hollow Steel Column

  • Nurizaty, Z.;Mariyana, A.A.K;Shek, P.N.;Najmi, A.M. Mohd;Adebayo, Mujedu K.;Sif, Mohamed Tohami M.A;Putra Jaya, Ramadhansyah
    • 국제초고층학회논문집
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    • 제10권4호
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    • pp.335-344
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    • 2021
  • In structural engineering practice, understanding the performance of composite columns under extreme loading conditions such as high-rise bulding, long span and heavy loads is essential to accuratly predicting of material responses under severe loads such as fires or earthquakes. Hitherto, the combined effect of partial axial loads and subsequent elevated temperatures on the performance of hollow steel column filled fly ash concrete have not been widely investigated. Comprehensive test was carried out to investigate the effect of elevated temperatures on partial axially loaded square hollow steel column filled fly ash concrete as reported in this paper. Four batches of hollow steel column filled fly ash concrete ( 30 percent replacement of fly ash), (HySC) and normal concrete (CFHS) were subjected to four different load levels, nf of 20%, 30%, 40% and 50% based on ultimate column strength. Subsequently, all batches of the partially damage composite columns were exposed to transient elevated temperature up to 250℃, 450℃ and 650℃ for one hour. The overall stress - strain relationship for both types of composited columns with different concrete fillers were presented for each different partial load levels and elevated temperature exposure. Results show that CFHS column has better performance than HySC at ambient temperature with 1.03 relative difference. However, the residual ultimate compressive strength of HySC subjected to partial axial load and elevated temperature exposure present an improvement compared to CFHS column with percentage difference in range 1.9% to 18.3%. Most of HySC and CFHS column specimens failed due to local buckling at the top and middle section of the column caused by concrete crushing. The columns failed due to global buckling after prolong compression load. After the compression load was lengthened, the columns were found to fail due to global buckling except for HySC02.

과학로켓 및 소형 발사체를 이용한 준궤도 극초음속 비행시험 프로그램 (Sub-Orbital Hypersonic Flight Test Programs using Sounding Rockets and Small Launch Vehicles)

  • 김혜성;양원석;최정열
    • 한국항공우주학회지
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    • 제43권3호
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    • pp.243-256
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    • 2015
  • 극초음속 비행체 개발 연구의 일환으로 소형 발사체나 과학로켓을 이용한 여러 비행 시험 프로그램이 진행되었다. 국제 협력으로 진행된 호주의 HyShot 프로그램은 과학로켓을 이용한 대표적인 스크램제트 엔진 비행시험 프로그램이며, 이후 다양한 탑재체에 대한 유사한 극초음속 비행 시험 프로그램들이 진행되었다. 미국에서는 DARPA와 AFRL 및 ONR이 각각 Falcon HTV-2, X-51A 및 HyFly의 프로그램을 수행하였으며, 호주와 국제협력으로 HyCAUSE, HIFiRE 비행시험 프로그램을 수행하였다. 그 밖에도 프랑스는 X-51A과 유사한 LEA 프로그램을 진행하고 있으며, 러시아 및 중국, 인도는 극초음속 방위 체계 개발을 목표로 비행시험을 진행하고 있는 것으로 보인다. 본 논문에서는 향후 국내에서 유사 프로그램을 수행할 시 참고할 수 있도록, 이들 프로그램의 목표 및 기술 요소와 경과 및 프로그램 사이의 관계 등을 정리하였다.

Relations between rheological and mechanical properties of fiber reinforced mortar

  • Cao, Mingli;Li, Li;Xu, Ling
    • Computers and Concrete
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    • 제20권4호
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    • pp.449-459
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    • 2017
  • Fresh and hardened behaviors of a new hybrid fiber (steel fiber, polyvinyl alcohol fiber and calcium carbonate whisker) reinforced cementitious composites (HyFRCC) with admixtures (fly ash, silica fume and water reducer) have been studied. Within the limitations of the equipment and testing program, it is illustrated that the rheological properties of the new HyFRCC conform to the modified Bingham model. The relations between flow spread and yield stress as well as flow rate and plastic viscosity both conform well with negative exponent correlation, justifying that slump flow and flow rate test can be applied to replace the other two as simple rheology measurement and control method in jobsite. In addition, for the new HyFRCC with fly ash and water reducer, the mathematical model between the rheological and mechanical properties conform well with the quadratic function, and these quadratic function curves are always concave upward. Based on mathematical analysis, an optimal range of rheology/ flowability can be identified to achieve ideal mechanical properties. In addition, this optimization method can be extended to PVA fiber reinforced cement-based composites.

플라이애쉬 혼합시멘트에 미치는 Na$_2$SO$_4$의 영향 (The Effects of Na$_2$SO$_4$ on the Hydration of Fly ash Blended Cement)

  • 정석재;방완근;김창은
    • 한국세라믹학회지
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    • 제35권11호
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    • pp.1227-1232
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    • 1998
  • In order to prohibit the delay of early stage hydration activator Na2SO4 was added to Fly Ash blended ce-ment and its effects were investigated. Various measurements such as Compressive strength Heat of hy-dration Pore size distribution Hydration products Microstructure were evaluated and the results show that specimens of Fly Ash(50wt%) with 5% Na2SO4 dramatically improved the compressive strength because pozzolanic reaction of Fly Ash and the formation of ettringite make th microstructure denser than OPC and flyash cement paste.

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플라이 애쉬-석회계 수열반응에 있어서 석고 및 시멘트의 영향 (Effect of Gypsum and Cement on Hydrothermal Reaction in Fly Ash-Lime System)

  • 안민선;박태균;황인수;김병익
    • 한국세라믹학회지
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    • 제35권10호
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    • pp.1030-1039
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    • 1998
  • In fly ash-lime system the effects of reaction condition amounts of gypsum and cement and CaO/SiO2 ratio on the hydrates by hydrothermal reaction were investigated. The tobermorite phases were not observed in hy-drothermal reaction of fly ash lime because of the hydrate rate was very slow. The compressive strength and the hydration rate increased with increasing the amount of gypusm and cement and the optimum amounts of gypsumo and cement were 5wt and 20wt% respectively. The specimen which CaO/SiO2 ratio is 0.85 was shown the maximum compressive strength and the tobermorite phase within reaction time 2 hours.

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Black soldier fly (Hermetia illucens) larvae oil as an alternative fat ingredient to soybean oil in laying hen diets

  • Kim, Byeonghyeon;Kim, Minji;Jeong, Jin Young;Kim, Hye Ran;Ji, Sang Yun;Jung, Hyunjung;Park, Seol Hwa
    • Animal Bioscience
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    • 제35권9호
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    • pp.1408-1417
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    • 2022
  • Objective: The objective of this study was to determine whether dietary black soldier fly (Hermetia illucens, HI) larvae oil (HILO) could serve as an alternative fat source to soybean oil (SBO) in laying hen diets. Methods: We randomly assigned 25-week-old Hy-line Brown laying hens (n = 144) to receive (n = 6 hens/group; eight replicates) a control or an experimental diet in which SBO was replaced with 50% (50HILO) or 100% HILO (100HILO). Results: Dietary HILO did not negatively affect body weight or productive performance during the study. The eggs also had similar quality parameters, proximate composition, and cholesterol levels. However, the yolk color index was significantly higher (p<0.01) in the 100HILO than in the other groups. Dietary HILO significantly altered the composition of fatty acids (FAs) in abdominal fat and eggs. Total saturated fatty acids (SFAs) and total polyunsaturated FAs (PUFAs) were significantly increased and decreased in the 50HILO and 100HILO groups, respectively, compared with those in the control group (p<0.001 and p<0.0001, respectively). Specifically, the medium-chain FAs lauric and myristic acids were remarkably increased in the abdominal fat of laying hens fed HILO (p<0.0001), whereas only myristic acid increased in eggs (p<0.0001). Undesirable heavy metal (aluminum, fluorine, arsenic, lead, mercury, and cadmium) concentrations were below permissible limits in eggs. Conclusion: We considered that HILO could be an alternative dietary fat to SBO for laying hens with maintained productive performance and good egg quality.