• 대한임상전기생리학회지
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• 제1권2호
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• pp.21-30
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• 2003

The purpose of this study was to know the effect of aquatic-exercise on muscle atrophy which induced by steroid injection. The forty-eight Sparague-Dawley adult male rats were assigned to the 4 groups; GroupI(distilled water injection), GroupII(steroid injection), GroupIII(distilled water injection and aquatic exercise), GroupIV(steroid injection and aquatic exercise). We observed their body weight, histological change by PAS stein. The results of this study were as follows; 1. After 2 weeks, the change of weights appeared that non-steroid injection groups increase weight and steroid injection groups decreased weight hasty. after 4 weeks, weights recovered from weight before test. It was possible to explain the change of weight by type II muscle fiber increase. 2. In histological change of muscle fibers, atrophy didn't observed in test group I, because type II muscle fibers were developed well. we observed not only injury of muscle fiber and muscle atrophy but specifically grouping type I muscle fiber in test group II. normal arrangement of muscle fibers were visible in test group and type II muscle fibers increased. we could observe muscle recovery because of type II muscle fibers increase in test group IV. therefore, it was seem that type II cell was recovering through aquatic exercise.

• 한국건축시공학회지
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• 제2권3호
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• pp.131-138
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• 2002

The objective of the study is to examine the characteristic correlations between reinforcing carbon fiber and interfacial adhesion agent since the interfacial adhesion strength between reinforcing carbon fiber and matrices is believed to be an essential element influencing the physical properties in carbon fiber reinforced cement composite using slurry method. The integrity of interfacial adhesion between reinforcing fiber and cement not only affects the quality of fiber reinforced cement composite but also influences to a large degree the physical properties of the cement composite when producing carbon fiber reinforced cement composite using slurry method. Having analyzed the physical properties 1.e., water content, tensile strength, flexural strength and flexural toughness of carbon fiber reinforced cement composite specimens, C-PAM(cation polyacrylamide) was determined to be an optimum interfacial adhesion agent. The study has also demonstrated that interfacial adhesion strength varies largely on the content and type of the reinforcing fiber. Judging from magnified view of the tensile shear cross-section using VMS(video microscope system), interfacial adhesion strength between reinforcing fiber and matrices is affected by the type of interfacial adhesion agent. According to the result of the experiments, C-PAM was determined to be an ideal interfacial adhesion agent when using carbon fiber in producing carbon fiber reinforced cement composite with the optimum content of carbon fiber being established.

• Structural Engineering and Mechanics
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• 제66권4호
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• pp.477-485
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• 2018

This study aims to investigate the influence of individual and hybrid fiber on the local bond-slip behavior of medium and high strength concrete after exposure to different high temperatures. Tests were conducted on local pullout specimens (150 mm cubes) with a reinforcing bar embedded in the center section. The embedment lengths in the pullout specimens were three times the bar diameter. The parameters investigated include concrete type (control group: ordinary concrete; experimental group: fiber concrete), concrete strength, fiber type and targeted temperature. The test results showed that the ultimate bond stress in the local bond stress versus slip curve of the high strength fiber reinforced concrete was higher than that of the medium strength fiber reinforced concrete. In addition, the use of hybrid combinations of steel fiber and polypropylene fiber can enhance the residual bond strength ratio of high strength concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.305-308
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• 2006

This paper is to investigate the strength, impact endurance and shrinkage of wet spraying type fiber composite mortar for repair material depending on fiber type and product kinds. Fiber composite mortar containing PVA fiber had the highest strength compared to that using any other fiber. Especially, The use of PVA fiber results in a remarkable enhancement in impact strength and an improved volumetric stability. Accordingly, it is confirmed that fiber composite mortar containing PVA fiber has remarkable performance as repair material of damaged section of concrete.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.374-377
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• 2009

Glass fiber reinforced nylon has been used in many plastic industries. Mechanical properties of reinforced plastics depend upon types of glass fiber as well as loading of glass fiber. Tensile properties of glass fiber reinforced nylon66 have been studied for different glass fiber types and sizes. Types of glass fibers were circular and flat, and diameters were 7, 10, and 13 micrometers. Orientations of glass fibers in the matrix of nylon66 have been analyzed through X-ray CT. Tensile specimens were prepared by cutting out of square plates of $100{\times}100{\times}3mm$ with different angles such as 0, 45, and $90^{\circ}$ to the flow direction. As the loading of glass fiber increases to 45 wt% tensile strength increases up 2.5 times compare with neat nylon66. Anisotropic tensile strength has been observed and minimum tensile strength was measured in the specimen cut from perpendicular to the flow direction.

• 한국축산식품학회지
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• 제39권6호
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• pp.988-999
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• 2019

To investigate the relationship between muscle fiber characteristics and meat quality traits by age of Korean native black goat (KNBG), four muscles (longissimus dorsi, LD; psoas major, PM; semimembranosus, SM; gluteus medius, GM) were obtained from five adult goat (AG; 18 months old) and five young goat (YG; 9 months old). PM muscle had the highest fiber number percentage (FNP) and fiber area percentage (FAP) of type I, followed by SM, GM, and LD muscles. FNP and FAP of type IIB were significantly (p<0.001) higher in AG than those in YG. YG had higher L^* values but lower b^* values than AG. The highest L^* and b^* values were observed in LD muscle (p<0.001). Age and muscle type had detrimental (p<0.001) effect on shear force and collagen content for all muscle in AG as compared to YG. YG had significantly (p<0.001) higher myofibrillar fragmentation index (MFI) than AG for all four muscles. These results suggest that muscle fiber compositions of different muscle types of KNBG depend on age, resulting in variations of meat color, MFI, collagen content, and shear force.

• 콘크리트학회논문집
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• 제14권4호
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• pp.474-482
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• 2002

본 연구의 목적은 섬유의 부착시험을 통하여 섬유의 파괴없이 최대 인발저항을 가지고 시멘트 모체 내에서 완전한 정착작용을하는 구조용 합성섬유의 최적형상과 최적형상함수를 도출하는데 있다. 7가지 다른 형상의 구조용 합성섬유를 조사하였고 부착시험을 수행하였다. 부착시험의 변수는 7가지의 다른 형상이고, 2종류의 시멘트 모르타르의 배합이다. 부착시험 결과, 7가지 다른 형상중 crimped type이 계면인성(인발에너지)와 인발하중에서 가장 우수한 성능을 보였다. Crimped type을 기본으로 하여 섬유의 주기와 높이를 바꾸어 부착시험을 실시한 결과 최적형상함수, D= $b^{{\alpha}ο{\alpha}}$ $h^{λ{\beta}}$ 를 도출하였다.

• 콘크리트학회지
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• 제10권4호
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• pp.101-111
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• 1998

본 논문의 목적은 전단내력이 부족한 R/C보에 CFS(Carbon Fiber Sheets), CFRP(Carbon Fiber Reinforced Plastic), GFRP(Glass Fiber Reinforced Plastics)를 이용해 전단보강을 할 경우에 보의 역학적 거동특성을 규명하기 위한 것이다. 본 논문의 목적을 달성하기 위하여 총 19개의 시험체가 제작되었으며, 실험변수로는 전단스팬비, 보강재료, 보강방법, 보강간격 및 방향을 산정하였다. 본 논문의 실험결과, FRP를 이용해 전단내력이 부족한 R/C보에 보강을 하였을 경우 약 50~70%정도의 보강효과를 나타내었다. 또한 소성이론에 근거한 철근콘크리트보의 전단강도 예측모델을 개발하였고 실험치와의 비교를 통해 개발된 모델의 적합성을 검증하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.33-38
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• 2001

This study aims to systematically research the various phenomena which arise from compression molding of fiber reinforced plastic composites. Long fiber reinforced plastic composites are rib type compression molded in order to measure the orientation in products, and the specimens are photographed with soft X-ray. The intensity of the photograph is applied by an image scanner, and the fiber orientation distribution of products is measured by using an image processing technique.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.660-665
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• 1993

An elastic model is developed to predict the average thermal residual stresses in the matrix and fiber of a misoriented short fiber composite. The thermal residual stresses are induced by the mismatch in the coefficient of the thermal expansion of the matrix and fiber when the composite is subjected to a uniform temperature change. The model considers two special cases of fiber misorientation ; two-dimensional in-plane and three-dimensional axisymmetric. The analytical formulation of the model is based on Eshelby's equivalent inclusion method and is nuque in that it is able to account for interactions among fibers. The model is more general than past models and it is able to treat prior analyses of the simpler composite systems as extram cases. The present model is to investigate the effects of fiber volume fraction, distribution type, distribution cut-off angle, and aspect ratio on thermal residual stress for both in-plane and axisymmetric fiber misorientation. Fiber volum fraction, aspect ratio, and disturbution cut-off angle are shown to have more significant effects on the magnitude of the thermal residual stress than fiber distrubution type for both in-plane and axisymmetric misorientation.