• Journal of Species Research
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• 제7권4호
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• pp.340-347
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• 2018

Four psammocinian species(Demospongiae: Dictyoceratida: Irciniidae) are described from Gageodo and Jejudo Islands, Korea. Among them, three are new species, Psammocinia rana, P. massa and P. vermins, which are very different from other recorded species. Secondary fibres of Psammocinia rana are mostly wide platelike shape with large perforation. Primary and secondary fibres of Psammocinia massa are lumped together in a thick mass through numerous areas. Psammocinia vemis is similar to P. mosulpia in skeletal structure, but differs in size of cored sands in primary fibres. The fourth species, we reclassify from Ircinia chupoensis to Psammocinia chupoensis based on more detailed observation of the skeletal structure. Ircinia only has sand cored primary fibres, while the observed species, has sand cored primary and secondary fibres.

• Animal Systematics, Evolution and Diversity
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• 제36권4호
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• pp.277-284
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• 2020

Four new species of genus Scalarispongia (Demospongiae: Dictyoceratida: Thorectidae) are described from Jejudo Island, Korea. These new species of Scalarispongia are compared with 14 reported species of the genus by the skeletal structure. Scalarispongia songakensis n. sp. is similar to S. lenis in sponge shape but differs in skeletal structure and meshes are not divided into two sections. The length of secondary fibres between primary fibres of this new species is much longer than S. lenis'. Scalarispongia radicula n. sp. is resembles S. songakensis in sponge shape, but this new species has pseudo-tertiary fibres at the sponge base. Scalarispongia maraensis n. sp. is very similar to S. subjiensis in sponge shape but primary fibres of this new species are not simple because fibres have wide webbing. Scalarispongia massa n. sp. is characterized by the large mass sponge shape and numerous open oscules form a long ling on the ridge of the sponge.

• Journal of Species Research
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• 제13권1호
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• pp.32-40
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• 2024

Five new species of the genus Hyattella (Dictyoceratida: Spongiidae) were collected from Jejudo and Gageodo, Korea: Hy. gukheulensis n. sp., Hy. regularis n. sp., Hy. lenis n. sp., Hy. membrana n. sp., and Hy. asper n. sp. Hyattella gukheulensis n. sp. is similar to Hy. munseomensis Sim et al., 2015 in shape, but differs in skeletal structure. Hyattella regularis n. sp. is close to Hy. bakusi Sim et al., 2015 but differs in regular secondary fibres at the surface membrane. Hyattella lenis n. sp. is unique by having numerous windings at the surface. Hyattella membrana n. sp. is similar to Hy. bakusi Sim et al., 2015 in shape, but differs in surface and skeletal fibres. Hyattella asper n. sp. is close to Hy. lendenfeldi Sim and Lee, 2014 in skeletal fibres, but differs in thin secondary fibres. This new species has numerous dense cored primary fibres.

• Animal Systematics, Evolution and Diversity
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• 제30권4호
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• pp.248-259
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• 2014

This paper describes eight new species of the genus Coscinoderma from Chuuk Island, the Federated States of Micronesia. This genus is characterized by very fine, meandering uncored secondary fibres. All the new Coscinoderma species are compared with eight other valid species from tropical regions. Coscinoderma folium n. sp. is characterized by its large thickly foliate shape, and cored primary fibres are easily found between secondary fibres in choanosome. Coscinoderma lacium n. sp. differs in having round conules and no cored primary fibres. Coscinoderma cavernosa n. sp. is distinguished from other species by its cavernous shape and long sharp conules. Coscinoderma wenoa n. sp. is characterized by long conules and primary fibres. Coscinoderma mappula n. sp. differs in having a thick sand crust in the choanosome. Coscinoderma bakusi n. sp. is characterized by having several oscules at the top of the sponge and color changed grey to dark brown in alcohol. Coscinoderma pollax n. sp. is characterized by having a small thumb shape. Coscinoderma truki n. sp. similar to C. pollax in shape but differs in cored primary fibres with many spicules.

• International Journal of Concrete Structures and Materials
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• 제10권3호
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• pp.325-335
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• 2016

This paper studies the effects of steel fibre geometry and architecture on the cracking behaviour of steel fibre reinforced concrete (SFRC), with the reinforcements being four types, namely 5DH ($Dramix^{(R)}$ hooked-end), 4DH, 3DH-60 and 3DH-35, of various hooked-end steel fibres at the fibre dosage of 40 and $80kg/m^3$. The test results show that the addition of steel fibres have little effect on the workability and compressive strength of SFRC, but the ultimate tensile loads, post-cracking behaviour, residual strength and the fracture energy of SFRC are closely related to the shapes of fibres which all increased with increasing fibre content. Results also revealed that the residual tensile strength is significantly influenced by the anchorage strength rather than the number of the fibres counted on the fracture surface. The 5DH steel fibre reinforced concretes have behaved in a manner of multiple crackings and more ductile compared to 3DH and 4DH ones, and the end-hooks of 4DH and 5DH fibres partially deformed in steel fibre reinforced self-compacting concrete (SFR-SCC). In practice, 5DH fibres should be used for reinforcing high or ultra-high performance matrixes to fully utilize their high mechanical anchorage.

• Advances in concrete construction
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• 제2권4호
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• pp.309-324
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• 2014

In the design of reinforced concrete structural walls, in order to ensure adequate inelastic displacement behaviour and to sustain deformation demands imposed by strong ground motions, special reinforcement is considered while designing. However, these would lead to severe reinforcement congestion and difficulties during construction. Addition of randomly distributed discrete fibres in concrete improves the flexural behaviour of structural elements because of its enhanced tensile properties and this leads to reduction in congestion. This paper deals with effect of addition of steel fibres on the behavior of high performance fibre reinforced cement concrete (HPFRCC) slender structural walls with the different volume fractions of steel fibres. The specimens were subjected to quasi static lateral reverse cyclic loading until failure. The high performance concrete (HPC) used was obtained based on the guidelines given in ACI 211.1 which was further modified by prof.Aitcin (1998). The volume fraction of the fibres used in this study varied from 0 to 1% with an increment of 0.5%. The results were analysed critically and appraised. The study indicates that the addition of steel fibres in the HPC structural walls enhances the first crack load, strength, initial stiffness and energy dissipation capacity.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.301-313
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• 2017

This paper presents the fibre-matrix interfacial properties of hooked end steel fibres embedded in ultra-high performance mortars with various water/binder (W/B) ratios. The principle objective was to improve bond behaviour in terms of bond strength by reducing the (W/B) ratio to a minimum. Results show that a decrease in W/B ratio has a significant effect on the bond-slip behaviour of both types of 3D fibres, especially when the W/B ratio was reduced from 0.25 to 0.15. Furthermore, the optimization in maximizing pullout load and total pullout work is found to be more prominent for the 3D fibres with a larger diameter than for fibres with a smaller diameter. On the contrary, increasing the embedded length of the 3D fibres did not result in an improvement on the maximum pullout load, but increase in the total pullout work.

• Advances in concrete construction
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• 제12권6호
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• pp.469-477
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• 2021

Keratin fibres are waste products of the poultry industry. Natural materials made from chicken feather fibres (CFFs) are used in concrete-reinforced composites in this study. Brittleness is a major problem of high-strength concrete (HSC) that leads to sudden failure at the ultimate capacity of concrete. Hence, this work aims to investigate effects of using CFFs on improving the brittle behaviour of HSC. Two scenarios are performed to analyse the effectiveness of using CFFs. HSC containing different ratios of CFF (0% as the control, 0.5%, 1%, 1.5%, 2%, and 3%) by volume are tested in the first scenario. Glass fibres (GF) are used to replace CFFs in the other scenario. Tests of fresh, hardened and morphological properties for concrete are performed. Results showed the enhanced brittle behaviour of HSC when using both types of fibres. The preferable ratio of both types of fibres is 1% by volume. Flexural and splitting tensile strengths increased by about 44.9 % and 42.65 % for mixes containing 0.1% GF, respectively. While they were increased by about 21.6 % and 21.16 % for mixes containing 0.1% CFF, respectively.

• 한국동물학회지
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• 제38권3호
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• pp.348-355
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• 1995

배추흰나비 유충 뇌에 분포하는 세로토닌 면역반응성 신경원(이하 세로토닌 세포)이 발생에 따라 형태학적으로 어떻게 분화해 나가는지를 조사하였다. 1령 유충뇌와 2령 유충뇌는 각각 20개의 세로토닌 세포를 포함하였다. 1령 유충뇌에서는 세로토닌 면역 반응성 섬유(이하 세로토닌 섬유) 한무리가 뇌교련을 형성하였고 이같은 섬유의 대부분은 반대쪽 중앙 신경망에 종지하였다. 2령 유충의 뇌에서는 세로토닌 섬유의 대부분이 뇌교련을 형성하였고 1령 유충뇌에서 보다는 그들의 수가 더 많이 관찰되었다. 이 섬유의 종말이 형성하는 보다 풍부한 arborization은 중앙 신경망의 상당한 부분을 차지하였다. 3령 유충뇌의 세로토닌 세포는 22개 였고 세로토닌 섬유들의 구성하는 뇌교련수도 3개로 증가되었으며 세로토닌 섬유의 대부분은 뇌교련을 형성하였다. 30개의 세로토닌 섬유뿐만 아니라 뇌의 전후 방향으로 달리는 세로토닌 섬유도 포함하였다.

• Advances in concrete construction
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• 제10권2호
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• pp.171-183
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• 2020

The main objective of this study is the assessment of the ability of limestone mortars to resist to different chemical attacks. The ability of polypropylene (PP) fibres waste used as reinforcement of these concrete materials to enhance their durability is also studied. Crushed sand 0/2 mm which is a fine limestone residue obtained by the crushing of natural rocks in aggregates industry is used for the fabrication of the mortar. The fibres used, which are obtained from the waste of domestic plastic sweeps' fabrication, have a length of 20 mm and a diameter ranging between 0.38 and 0.51 mm. Two weight fibres contents are used, 0.5 and 1%. The durability tests carried out in this investigation included the water absorption by capillarity, the mass variation, the flexural and the compressive strengths of the mortar specimens immersed for 366 days in 5% sodium chloride, 5% magnesium sulphate and 5% sulphuric acid solutions. A mineralogical analysis by X-ray diffraction (XRD) and a visual inspection are used for a better examination of the quality of tested mortars and for better interpretation of their behaviour in different solutions. The results indicate that the reinforcement of limestone mortar by PP fibres waste is an excellent solution to improve its chemical resistance and durability. Moreover, the presence of PP fibres waste does not affect significantly the water absorption by capillarity of mortar nether its mass variation, when exposed to chloride and sulphate solutions. While in sulphuric acid, the mass loss is higher with the presence of PP fibres waste, especially after an exposure of 180 days. The results reveal that these fibres have a considerable effect of the flexural and the compressive behaviour of mortar especially in acid solution, where a reduction of strength loss is observed. The mineralogical analysis confirms the good behaviour of mortar immersed in sulphate and chloride solutions; and shows that more gypsum is formed in mortar exposed to acid environment causing its rapid degradation. The visual observation reveals that only samples exposed to acid attack during 366 days have showed a surface damage extending over a depth of approximately 300 ㎛.