본 논문에서는 아라미드 스트립을 이용하여 영구거푸집을 제작하고 철근 콘크리트 기둥에 적용하여 성능을 평가하였다. 보강된 철근콘크리트 기둥의 구조거동을 평가하기 위하여 총 3개의 기둥을 제작하였다. 1개의 실험체는 무보강 실험체로서 비내진 상세의 기둥이며 다른 두 실험체의 경우 내진설계가 적용되거나 아라미드 섬유보강 영구거푸집으로 보강하였다. 기둥의 전형적인 성능평가를 위하여 일정한 축하중하에서 정적반복가력 실험을 수행하였다. 실험결과 무보강 실험체와 비교하여 전단 강도, 연성 및 에너지 소산능력을 증가시켰으며 반복하중으로 인한 강도 및 강성 저감에서 우수한 성능을 보였다. 따라서, 본 연구에서 제안한 아라미드 보강 영구거푸집은 기존 RC 기둥의 내진성능을 향상시킬 수 있을 것으로 판단된다.

Interfacial adhesion between carbon fiber and epoxy resin mostly determine the mechanical properties of the carbon fiber/ epoxy composites and the chemical structures of epoxy resin and hardener plays an important role. In this regard, stereoisomerism of epoxy hardeners, such as 3,3′ and 4,4′-DDS (diaminodiphenylsulfone), can have significant influence on the fracture toughness of the cured epoxy and related carbon fiber composites. Therefore, this study aims to investigate the influence of stereoisomerism of epoxy hardeners on fracture toughness of the carbon fiber/epoxy composites. Triglycidyl aminophenol (TGAP) are selected as epoxy resin and 3,3′- and 4,4′-DDS are selected as epoxy hardener. Wetting behaviors and fiber matrix adhesion of TGAP/DDS mixtures onto carbon fiber are investigated and fracture toughness (KIC) of TGAP/ DDS mixtures are also investigated. Then, the mode II fracture toughness test of the carbon fiber/TGAP/DDS composites are carried out to investigate the influence of hardener stereoisomerism on fracture toughness of the resulting composites. Wetting and fiber matrix adhesion to carbon fiber of TGAP/3,3′-DDS was better than those of TGAP/4,4’-DDS and KIC of TGAP/3,3′-DDS was also better than that of TGAP/4,4′-DDS. As a result of the synergistic effect of better wetting, fiber matrix adhesion, and fracture toughness of TGAP/3,3′-DDS, the mode II fracture toughness of the carbon fiber/ TGAP/3,3’- DDS composites was almost twice of that of the carbon fiber/ TGAP/4,4′-DDS composites. Based on the results reported in this study, stereoisomerism of the epoxy hardeners can influence the fracture toughness of the resulting composites as well as that of the resin itself. In other words, only small difference, such as the spatial arrangement of the molecular structure of epoxy hardeners can cause huge difference in the mechanical properties of the resulting composites.

The widespread use of automobiles has greatly increased energy demand and exhaust gas pollution. In order to save energy, reduce emissions and protect the environment, making lightweights automobiles is an effective measure. In this paper, carbon fiber composites and automobile B-pillars are briefly introduced, and then the mechanical properties and impact resistance of the DC590 steel B-pillars and carbon fiber composites B-pillars are simulated by the ABAQUS finite element software. The results show that the quality of compound B-pillars is reduced by 50.76 % under the same dimensions, and the mechanical property of unit mass is significantly better than that of metal B-pillars. In the course of a collision, the kinetic energy of the two B-pillars is converted into internal energy, but the total energy remains the same; the converted internal energy of the composite B-pillars is greater, the deformation is smaller and the maximum intrusion and intrusion speed is also smaller, indicating that the anti-collision performance of the composite B-pillars is excellent. In summary, the carbon fiber composites can not only reduce the quality of the B-pillars, but also improve their anti-collision performance..

A two-level full factorial design 22 with three replications was employed to assess the effect of the incorporation of PSF into the epoxy matrix and the surface treatment of carbon fibers on the work of adhesion (WA) and the interfacial shear strength (IFSS) of carbon fiber–epoxy composites. The IFSS was determined using the microbond (or microdrop) micromechanical test, and the work of adhesion was estimated using two different procedures: (1) using the Owens and Wendt method, and (2) from the Dupre–Young expression using the contact angle θ of a cured epoxy resin on a single carbon fiber and the surface energy of the cured epoxy resin. It was found that the treatment of the carbon fiber with the silane-coupling agent appreciably increases its polar component because of the nitric acid oxidation and the chemisorption of the silane-coupling agent onto the carbon fiber surface. Also, the O=S=O group present in the polysulfone chain resin fairly increases the polar component of the epoxy–PSF blend. The results show that the wetting of the silane-treated carbon fiber by the thermoplastic-modified epoxy resin is better, thus increasing the fiber–matrix adhesion. It was also found that there is a similarity between the trends of both, the IFSS and the WA results. Also, from the ANOVA results it was also seen that both the incorporation of the PSF to the epoxy matrix and the surface treatment of the carbon fibers and their interaction were statistically significant to the IFSS and the WA.

The objective of this study was to analyze proximate composition, dietary fiber, mineral content, fatty acid composition in Cheonggak (Codium fragile) in order to encourage the consumption of Cheonggak. The proximate composition of Cheonggak was found to be 5.51% moisture, 24.09% crude ash, 15.79% crude protein, 2.47% crude lipid and 45.31% dietary fiber. The major mineral content of Cheonggak was Na 8,950 mg/100 g, Mg 1,252 mg/100 g, Ca 807 mg/100 g, K 457 mg/100 g, and trace mineral content was Fe 26 mg/100 g, Mn 8 mg/100 g, Zn 0.4 mg/100 g. Palmitic acid 36.86% and α-linolenic acid 20.14% were the most contained fatty acids in Cheonggak. The ratio of saturated fatty acids to unsaturated fatty acids was 85.49% while ω-6 fatty acids to ω-3 fatty acids were 59.10%. Based on the proximate composition, dietary fiber, mineral content, and fatty acid composition, Cheonggak was judged to be a major source of dietary fiber and Mg and Ca, and it was deemed to be helpful in promoting health, including the prevention of hyperlipidemia. Cheonggak contained valuable nutrients similar to seaweed, which is produced and consumed the most in Korea. Thus, it is necessary to include Cheonggak in the food items.

Whisker-type magnesium hydroxide sulfate hydrate (5Mg(OH)2·MgSO4·3H2O, abbreviated 513 MHSH), is used in filler and flame-retardant composites based on its hydrate phase and its ability to undergo endothermic dehydration in fire conditions, respectively. In general, the length of whiskers is determined according to various synthetic conditions in a hydrothermal reaction with high temperature (~180oC). In this work, high-quality 513 MHSH whiskers are synthesized by controlling the concentration of the raw material in ambient conditions without high pressure. Particularly, the concentration of the starting material is closely related to the length, width, and purity of MHSH. In addition, a ceramic-coating system is adopted to enhance the mechanical properties and thermal stability of the MHSH whiskers. The physical properties of the silica-coated MHSH are characterized by an abrasion test, thermogravimetric analysis, and transmission electron microscopy.

본 연구에서는 다공성 Polyacrylonitrile (PAN) 중공사막을 지지체막으로 하여 Poly styrene sulfonic acid (PSSA) 와 polyethyleneimine (PEI)을 이용하여 layer-by-layer법으로 선택층을 형성시켰다. 코팅용액에 Mg염을 첨가하여 염석법(salting out method)을 이용하였다. 코팅용액의 이온세기, 고분자 농도, 코팅시간 등을 달리하여 나노여과막을 제조하였으며 NaCl, MgCl2, CaSO4 100 mg/L를 공급액으로 하여 2 atm의 구동 압력에서 투과도와 염 배제율을 평가하였다. PSSA 20,000 ppm, 코팅시간 3분, 이온세기 1.0, PEI 30,000 ppm, 코팅시간 1분, 이온세기 0.1의 조건으로 코팅한 막이 가장 우수한 성능을 보여 주었다. 100 ppm의 NaCl, MgCl2, CaSO4 공급액에서 각각 20.4, 19.4, 18.7 LMH의 투과도와 67, 90, 66.6%의 염 배제율을 나타내었다.

In this study, effects of gelatin extracted from chicken feet powder and wheat fiber on physicochemical properties of gel were determined. Gel samples were prepared with different concentrations of chicken feet gelatin powder (2, 3, and 4%) and wheat fiber (0, 1, and 2%). Gel strength increased (p<0.05) with increasing concentrations of both chicken feet gelatin powder and wheat fiber. In each gel sample, melting point and apparent viscosity of the gel was affected by different chicken feet gelatin powder concentrations irrespective of the wheat fiber concentrations (0, 1, or 2%). The 4% chicken feet gelatin powder induced the highest melting point among all gel samples regardless of the wheat fiber concentration. The gel sample with 4% chicken feet gelatin powder and 2% wheat fiber showed the highest values (p<0.05). With the increasing concentrations of wheat fiber, CIE L* increased in gel samples with chicken feet gelatin powder at 3 and 4% (p<0.05). Lower CIE a* was observed in gel samples with wheat fiber at 1 and 2% compared to gel samples without wheat fiber (p<0.05). CIE b* of gel samples with 2% chicken feet gelatin powder was decreased as increasing the addition level of wheat fiber (p<0.05). Consequently, our studies show that chicken feet gelatin powder and wheat fiber mixture could be used as a food ingredient since they have various effects on physicochemical properties of gel such as an effect on gel strength, melting point, viscosity, and color.

최근 국내 구조물들의 노후화가 진행됨에 따라 구조물 보강과 관련된 연구에 대한 관심이 높아지고 있다. FRP보강은 노후화가 진행되어 성능이 저하된 구조물을 보강하는데 사용되며 주로 유리섬유 및 탄소섬유를 사용한다. 그러나 이 두 가지의 섬유는 경제적으로나 환경적으로나 나쁜 점이 있다. 따라서 본 연구에서는 친환경적이고 내열성이 우수한 현무암 섬유를 구조 용 보강재로 제시하고자 하였다. 또한 본 연구에서는 현무암 섬유에 가장 적합한 수지를 찾기 위하여 에폭시, 폴리에스테르 및 비닐에스테르를 함침 하였다.그 결과, 에폭시 수지를 사용하였을 때 가장 높은 인장 강도 및 탄성계수를 보였으며 전단강도 및 전단탄성계수가 타 수지에 비하여 50%정도 높게 측정되었다. 현무암섬유와 탄소, 유리 섬유의 물성을 비교한 결과 인장강도는 CFRF의 약 60%정도이나 GFRP보다 30%정도 높게 나타내었다.

The purpose of this study is to optimize the extraction conditions (time, pH, and temperature) for water-soluble dietary fiber (SDF) and solids from Opuntia ficus-indica (OFI) stems and to evaluate the functionality of the optimized extract. The maximum extraction yield was obtained when 100% distilled water was used, indicating that ethanol hampered the extraction. The extraction yields were lower at higher temperatures and lower pHs. The maximum extraction of SDF (27.92%) and solids (5.6 g) was achieved with a 7-h extraction at 50oC and pH 7.0, with desirability being 0.958. The stem extract obtained under the optimum extraction conditions had an antioxidant capacity of 118.10 mg vitamin C equivalents (VCE) using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. In a medium containing 30% extract, the growth of E. coli was reduced by 34%, while that of B. cereus was reduced by 23%. These results suggest that OFI stems can be used as a functional resource.