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Comparison of structural design and future trends in composite hulls: A regulatory review
Han Zhiqiang,장재원,Souppez Jean-Baptiste R.G.,서형석,오대균 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-
Recently, the International Organization for Standardization (ISO) standards associated with composite hullstructure design, including the method for estimating the mechanical properties of laminates necessary for design, have been revised. This study reviews the revisions concerning materials and analyzes the design trend of composite hull structures by comparing eight related rules, including classification society and domestic rules. The results reveal that the current design trend of hull laminates is to thoroughly consider the impact of several variables, including the weight fraction of reinforcement (glass content; Gc), fabric combination, and fabrication method, on the laminate properties. For illustration, these effects were verified with a typical glass-fiberreinforced plastic vessel based on a case study, the experimental results of extant studies, and current standards. The industry design conditions, normal Gc (0.367) and high Gc (0.600), were selected and applied to two fabric combinations: chopped strand mat and chopped strand–woven roving. The hull laminate design results based on the revised ISO standards (ISO 12215) satisfied the safety and weight requirements for normal Gc in both cases. This may be attributed to the high mechanical properties suggested in the current standards regardless of how they reflect the effects of changes in fabric type, combination, and method on the mechanical properties of the laminates. For high Gc, the combination material case satisfied the safety requirements to a greater extent. and this can also be made lightweight. In contrast, the single material case based on the revised ISO standard may result in safety issues, mainly because the revised ISO standard reflects the adverse effects of design variables such as Gc and fabric blends on the laminate fabrication quality. Further, non-ISO rules should be revised in the future to reflect the effects of each variable in the material design according to the research trends of composite materials.
옥수수대 ( 藁稈 ) 및 자루 ( 穀實危含 ) 펠렛급여가 젖소 발육에 미치는 영향
김준식,김영근,오대균,지설하,최윤재,한인규 ( J . S . Kim,Y . K . Kim,D . K . Oh,S . H . Chee,Y . J . Choi,I . K . Han ) 한국축산학회 1985 한국축산학회지 Vol.27 No.2
A feeding trial with 20 heads of Holstein heifers was conducted for 90 days to investigate the feeding value of whole corn crop and corn ear with husk pellets. Four treatments were control, T₁ (corn ear pellet), T₂ (whole corn crop pellet) and T₃ (rice straw pellet). The results are summarized as follows. 1. Feeding corn ear pellet or whole corn crop pellet improved (p$lt;0.01) weight gain of dairy heifers with no significant differences between whole corn crop pellet and corn ear pellet, or between rice straw and control group. 2. Feed intake of experimental animals was higher in the order of T₁, T₂, T₃ and control group. However, the trend was not conclusive. 3. Feed cost per kilogram weight gain when expressed percent of control was 95.3, 94.6 and 11.1 for T₁, T₂ and T₃ group, respectively, indicating that feeding corn crop pellets was more economical for weight gain. Results from a present experiment show the feasiability of using whole corn crop pellet and corm ear pellet as a good feedstuff for ruminants.