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강화 섬유의 분산도가 SiC<sub>f</sub>/SiC 복합소재의 기계적 강도에 미치는 영향
최지범,김수현,이슬희,한인섭,방형준,김세영,성영훈,Ji Beom Choi,Soo-Hyun Kim,Seulhee Lee,In-Sub Han,Hyung-Joon Bang,Seyoung Kim,Young-Hoon Seong 한국복합재료학회 2023 Composites research Vol.36 No.3
This paper investigates the impact of fiber dispersion on the internal structure and mechanical strength of SiC<sub>f</sub>/SiC composites manufactured using spread SiC fibers. The fiber volume ratio of the specimen to which spread SiC fiber was applied decreased by 9%p compared to the non-spread specimen, and the resin slurry impregnated between the fibers more smoothly, resulting in minimal matrix porosity. In order to compare the fiber dispersion of each specimen, a method was proposed to quantify and evaluate the separation distance between fibers in composite materials. The results showed that the distance between fibers in the spread specimen increased by 2.23 ㎛ compared to the non-spread specimen, with a significant 42.6% increase in the distance between fiber surfaces. Furthermore, the 3pt bending test demonstrated a 49.3% higher flexural strength in the spread specimen, accompanied by a more uniform deviation in test data. These findings highlight the significant influence of SiC fiber dispersion on achieving uniform densification of the SiC<sub>f</sub>/SiC matrix and increasing mechanical strength.
김현우 ( Hyun Woo Kim ),이슬희 ( Seulhee Lee ),손호선 ( Hawsun Sohn ) 한국수산과학회(구 한국수산학회) 2021 한국수산과학회지 Vol.54 No.2
There are six species of pinnipeds in Korean waters. Because of the lack of research on pinnipeds, it has been difficult to obtain ecological information on each species. All six species have been designated as endangered species, marine protected species, or national monuments by the government, depending on historical records. In this study, the current status of pinnipeds in Korea was investigated through reviewing the literature, and sighting and bycatch records, with the intention of providing new information for the review of the six species. Spotted seals and northern fur seals are well known inhabitants of Korea. The southern part of the East Sea is thought to be the margin of the distribution of Steller sea lions. Sightings of ribbon seals and ringed seals were not confirmed in Korean waters. Sea lions have not been seen since their last sighting on Dokdo in 1951 and are thought to have become extinct after that. It is necessary to delist undistributed or extinct species in Korea from the marine protected species list.