• Computers and Concrete
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• 제31권5호
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• pp.433-442
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• 2023

This study presents the visually observed behavior of fibers embedded in concrete samples that were subjected to a flexural bending test. Three types of fibers such as macro polypropylene, macro polyethylene, and the hybrid of steel and polyvinyl alcohol were mixed with cement by a designated mix ratio to prepare a total of nine specimens of each. The bending test was conducted by following ASTM C1609 with a net deflection of 2, 4, and 7 mm. The X-ray computed tomography (XCT) was carried out for 7 mm-deflection specimens. The original XCT images were post-processed to denoise the beam-hardening effect. Then, fiber, crack, and void were semi-manually segmented. The hybrid specimen showed the highest toughness compared to the other two types. Debonding based on 2D XCT sliced images was commonly observed for all three groups. The cement matrix near the crack surface often involved partially localized breakage in conjunction with debonding. The pullout was predominant for steel fibers that were partially slipped toward the crack. Crack bridging and rupture were not found presumably due to the image resolution and the level of energy dissipation for poly-fibers, while the XCT imaging was advantageous in evaluating the distribution and behavior of various fibers upon bending for fiber-reinforced concrete beam elements.

• Fisheries and Aquatic Sciences
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• 제26권12호
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• pp.715-725
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• 2023

Microplastic (MP) pollution in aquatic environments is a growing concern worldwide. This study investigated the abundance, types, and attributes of MPs in the surface water at two industrial sites (Avoimitro Ghat and Kalurghat) along the Karnaphuli River in Chattogram, Bangladesh. Sampling was conducted over eight months across three transects encompassing a total area of 500 m at each site. A manta net of 200 ㎛ mesh size was used to sample MPs. The obtained samples were subsequently filtered, enumerated, and characterized using a stereo microscope and imaging software. The mean abundance of MP particles (per km² ) was found higher in Avoimitro Ghat (94,861 ± 57,126) than in Kalurghat (31,343 ± 23,183). A significant statistical difference (p < 0.05) was observed in the mean abundance of MP particles between the wet and dry seasons. The fragment group of MP exhibited the most abundant category, whereas the pellet category displayed the lowest. MPs with an elongated shape prevailed at both locations throughout all seasons. At Avoimitro Ghat, blue-colored MPs demonstrated the highest mean count, while in Kalurghat, the highest mean count belonged to brown-colored MPs. The size distribution of MPs differed between the two sites, with 1-2 mm MPs being plentiful in both seasons and Avoimitro Ghat, whereas MPs ranging from 500 ㎛ to less than 1 mm were abundant in Kalurghat. Ten (10) polymer types were found from Fourier-transform infrared spectroscopy (FTIR) analysis with high levels of polypropylene atactic in both Avoimitro Ghat (32%) and Kalurghat (17%). The findings provide important insights into MP pollution in the Karnaphuli River, which may aid in developing effective strategies to mitigate the impacts of MP pollution on the aquatic ecosystem and human health.

• 한국식품과학회지
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• 제48권3호
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• pp.247-255
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• 2016

우리나라에서 가장 많이 유통되고 있는 감자 품종인 '수미'를 사용하여 세척감자의 실용화를 위한 적정 포장재를 개발하고자 본 연구를 수행하였다. 세척감자의 포장재에 따른 품질특성의 변화를 구명하기 위해 무포장(NP, positive control), 종이봉투(PB, negative control), 양파망(ON), 무공투명비닐백(TP), 유공불투명비닐백(OP) 총 5종의 포장재를 대상으로 Hunter 값, 색차값(${\Delta}E$ value), 총 엽록소 및 글리코알카로이드(PGA) 함량 등 품질 특성을 평가하였다. 그 결과, Hunter a값(적색도/녹색도)은 세척감자 저장 12일째에 양파망(ON)과 무공투명비닐백(TP)에서 -a값을 나타내 녹색도로 바뀌었다. 색차값은 무포장(NP)에서 높게 나타나 다른 포장재에 비해 녹화가 심했다. 총 엽록소 함량은 저장기간에 따라 뚜렷하게 증가하는 경향을 보였으며, 무포장에서 저장 15일째 가장 큰 증가를 보였다. 세척감자의 괴경 내피 부위의 PGA 함량은 모든 처리에서 저장 15일째 5 mg/100 g 이하로 낮았으며, 외피 부위에서도 4.5-9.3 mg/100 g으로 국제연합식량농업기구(FAO) 권장기준(20 mg/100 g)보다 낮았다. 녹화와 각 품질평가 요인의 상관성을 구명하기 위해, 피어슨 상관분석을 한 결과, 엽록소 함량은 색차값(0.90786)과 높은 정의 상관관계를 보였으나, Hunter a값은 색차값(-0.86021), 엽록소 함량(-0.85196)과는 높은 부의 상관관계를 보였다. 글리코알카로이드(PGA)와 녹색도 품질평가 요인과는 상관관계가 없는 것으로 나타났다. 이러한 엽록소 함량, 색도 색차와 PGA 함량 등의 결과를 바탕으로 녹화와 소비자 선호도를 고려할 때 평가항목에서 우수한 유공불투명포장재가 세척감자 소포장재로 유망할 것으로 판단되었다.

• 한국버섯학회지
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• 제11권4호
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• pp.292-296
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• 2013

주요 수출버섯인 큰느타리버섯의 신선도유지에 적합한 포장량 및 포장재 산소투과도를 설정하기 위해 저온 저장기간 중 품질변화를 분석한 결과, 포장량 및 포장재 산소투과도에 따른 저장기간 중 중량감모율 변화는 차이없었으며, 갓신장율은 포장량 200 g일 경우 산소투과율이 높을수록 저장기간이 길수록 증가하였으나, 400 g 처리는 산소투과도 3,000 $cc/m^2$, 24 h, atm일 때 가장 낮았다. 포장재 내부의 $O_2$함량은 포장량이 적을수록 산소투과도가 낮을수록 높았으며, $CO_2$함량은 포장량이 많을수록 높았다. 종합적으로 포장량 400 g, 포장재 산소투과도 2,000 $cc/m^2$, 24 h, atm 이하에서 판매가능한 신선도가 35일까지 유지되어 저장기간이 가장 길었다.