• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.147-153
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• 1991

In order to clarify the varietal differences of grain shedding in 86 rice varieties with the diverse origin, a bundle of 10 panicles was fallen down on the bottom above 2m height, and several characters related to shattering were investigated. The ratio of grain shedding in the varieties from the Tongil types was the greatest (11. 29%), followed by the native and J aponica types (2.56, 0.17%). The breaking tensile and breaking bending strengths of the primary rachis-branch in the Tongil types were weaker than in the native and Japonica types with mean values of 217g and 20.5g, respectively. The fiber cells length of the primary rachis- branch in the Tongil types were shorter in the native and Japonica types. The ratio of grain shedding was significantly correlated with the breaking tensile and bending strengths of the primary rachis- branch, and fiber cell length.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.328-336
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• 2004

This paper describes the effect of loading rate, specimen geometries and material properties for ModeⅠ and Mode Ⅱ interlaminar fracture toughness of hybrid composite by using double cantilever beam (DCB) and end notched flexure (ENF) specimen. In the range of loading rate 0.2~20mm/min, there is found to be no significant effect of loading rate with the value of critical energy release rate (Gc).The value of Gc for variation of initial crack length are nearly similar values when material properties are CF/CF and GF/GF, however, the value of Gc are highest with the increasing intial crack length at CF/GF. The SEM photographs show good fiber distribution and interfacial bonding of hybrid composites when the moulding is the CF/GF.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.262-268
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• 2003

This paper describes the effect of loading rate, specimen geometries and material properties for Mode I interlaminar fracture toughness of hybrid composite by using double cantilever beam (DCB) specimen. In the range of loading rate 0.2-20mm/min, there is found to be no significant effect of loading rate with the value of critical energy release rate (G_IC). The value of $G_IC$ for variation of initial crack length are nearly similar values when material properties are CF/CF and GF/GF, however, the value of $G_IC/$ are highest with the increasing initial crack length at CF/GF. The SEM photographs show good fiber distribution and interfacial bonding of hybrid composites when the moulding is the CF/GF

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.677-684
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• 2007

This study investigates the failure mechanism of RC beams strengthened with GFRP (glass fiber reinforced polymer) sheets. After analyzing failure mechanisms, the various methods to prevent the debonding failures, such as increasing bonded length of GFRP sheets, U-shape wrappings and epoxy shear keys are examined. The bonded length of GFRP sheets are calculated based on the assumed bond strengths of epoxy resin. The U-shape wrappings are either adopted at the end or center of the CFRP sheets bonded to the beam soft. The epoxy shear keys are embedded to the beam soft to provide sufficient bond strength. The end U-wrappings and the center U-wrappings are conventional, while epoxy shear keys are new details developed in this study. A total six half-scale RC beams have been constructed and tested to investigate the effectiveness of each methods to prevent debonding failure of GFRP sheets. From the experimental results, it was found that increasing bonded length or end U-wrappings do not prevent debonding failure. On the other hand, the beams with center U-wrappings and shear keys reached an ultimate state with their sufficient performance. The center U-wrappings tended to control debonding of the longitudinal GFRP sheets because the growth of the longitudinal cracks along the edges of the composites was delayed. In the case of shear keys, it was sufficient to prevent debonding and the beam was failed by GFRP sheets rupture.

• Journal of Periodontal and Implant Science
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• v.35 no.1
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• pp.153-161
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• 2005

파이브로넥틴은 세포외기질에 존재하는 당단백질로 세포의 부착, 이동, 성장 및 분화에 관여하며, 섬유아세포 성장인자는 세포의 증식 이동 및 분화에 영향을 주는 중요한 성장인자로 알려져 있다. 최근 연구에 의하면, 파이브로넥틴은 조골세포의 타이태늄 임플란트 표면으로 이주와 증식 및 골생성을 촉진하며, 섬유아세포 성장 인자는 파이브로넥틴에 상승작용을 한다고 보고된 바 있다. 이 실험의 목적은 파이브로넥틴 및 섬유아세포 성장인자의 복합 단백질을 이용하여 타이태늄 임플란트의 골 반응을 알아보는 것이다. 체중 2.5 kg 내외의 건강한 18 마리의 웅성가토를 준비하여 무균 사육하였고, 순수 타이태늄을 절삭가공하여 직경 3.5mm, 길이 6mm 의 machined surface를 지니는 screw type 의 임플란트를 준비하였다. 사람의 유전자를 기초로, 유전자 재조합법을 통해, 적절한 primer를 이용하여 얻은 섬유아세포 성장인자를 파이브로넥틴 III 형 분절의 9-10 번 도메인에 결합시켜 얻은 복합 단백질을 준비된 임플란트에 표면처리하여 실험군으로 하였고, 표면처리하지 않은 임플란트를 대조군으로 하여, 가토의 좌우 경골에 각각 2 개씩의 임플란트를 식립하였다. 4주 후, 가토를 희생시켜 각 경골 당 한 개의 임플란트에서 뒤틀림 제거력을 측정하였고 나머지 임플란트 식립 부위 에서는 경골을 포함하는 조직표본을 제작하였다. 조직표본상에서 골접촉이 가장 좋은 3 개의 나사산의 길이를 측정하고, 나사와 접촉하는 골의 길이를 측정하여 골-임플란트 접촉도를 구하고, 같은 부위에서 나사산 사이의 면적과 골이 차지하는 면적을 비교하여 골생성률을 얻었다. 실험군과 대조군의 결과는 Student t-test 를 이용하여 신뢰도 95% 수준에서 통계학적 유의성을 검정하였다. 파이브로넥틴과 섬유아세포 성장인자의 복합 단백질로 표면처리된 임플란트와 표면처리를 하지 않은 임플란트는 뒤틀림 제거력에서는 통계적 유의성이 나타나지 않았으나, 골-임플란트 접촉도와 골생성률에서 복합 단백질로 처리된 임플란트가 통계적으로 유의하게 높은 결과를 보였다. 이상의 연구결과로, 섬유아세포 성장인자와 파이브로넥틴 복합 단백질로 처리한 타이태늄 임플란트가 주변 골 형성을 촉진시켜, 골유합을 증진시킴을 알 수 있었다. 따라서, 복합 단백질이 타이태늄 임플란트의 성공률을 높이기 위한 표면개질 물질로 이용될 가능성을 확인할 수 있었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.4
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• pp.159-165
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• 2021

The fiber composites have been investigated as lightweight structure material platforms for aerospace applications because their strength can be enhanced by adding reinforcement without a significant increase in weight. In this study, the fabrication and characterization of carbon nanotube (CNT) reinforced glass fiber composites are demonstrated to enhance the tensile strength of longitudinal direction along the glass fibers. Due to the reinforcement of CNT in epoxy layers, the yield strength of fiber/epoxy composites is enhanced by about 10 %. Furthermore, using scanning electron microscopy, analysis of fracture surfaces shows that mixed CNT in epoxy layers acts as necking agents between fractured surfaces of fiber/epoxy; thereby, initiation and evolution of crack across fiber composite can be suppressed by CNT necking between fractured surfaces.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.505-511
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• 2004

The effects of single cells of carrot or radish on the fecal excretion, mineral absorption rate and structure of small intestine and colon were investigated in rats fed 5% single cell diet for 4 weeks. Carrot contained 28.76% of total dietary fiber and 21.45% of insoluble dietary fiber, and radish contained 23.14% of total dietary fiber and 16.77% of insoluble dietary fiber on a dry weight basis. Total dietary fiber contents of the single cell were 44.68% for carrot, 48.0% for radish. Absorption rates of magnesium were higher in the carrot and radish single cell groups than the other groups. Cellulose significantly increased fecal weight and weight of small intestine. The consumption of cellulose and single cells decreased digestibility of lipid. The length of colon were longer in the carrot and the radish group than the other groups. Scanning electron microscopy studies showed that small intestine microvilli with leaf-shaped were seen in cellulose and single cell fed groups. These results suggest that the diet containing 5% single cells of carrot or radish increases the digestibility of dietary fiber, weight gain, and fecal output and shorten the gastrointestinal transit time.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.1014-1021
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• 1997

Studies were carried out on the preparation of several kinds of pulps from Sponge gourd fiber by KP, ASP, SP PAP, AP and addition of AQ pulping process. These unbeaten and beaten pulping fibers were observed their characteristics and fiber structure by SEM, FQA, Image analyzer and Micro projector. The results were summarized as follows; 1) The cooking condition which is the possible defibrilation of Shives are KP base($160^{\circ}C$, 2hr.), ASP base($155^{\circ}C$, 4hr.), PAP base($160^{\circ}C$, 1hr.). From the results, the kappa no. had the range of 12, 25, 10 each other. 2) The pulp yields of sponge gourd fiber obtained the range of KP 50~55%, ASP&60~70% and PAP 45~50%. SP base have the highest and contnets of KP&PAP base are much the same as woods. 3) Increasing amount of NaOH on Pulping was accelerated the defibrilation of Shives and was changed a morphology of pulping fiber quality such as fiber length, curl and kink index. 4) Addition of AQ on pulping process of sponge gourd fiber had a affect to raise the rate of delignification while protecting cellullosic components against degradation, especially defibrilation was very excellent, beated pulp much more easily and increased the fibrilation. 5) ASP system have higher bulk density, fiber bonding and protecting cellullosic components against degradation than KP or PAP. 6) The color reactions of the "C" stain solution showed blue or blue-gray with clean and transparency thin cell wall.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.202-205
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• 2003

Investigated whether fiber orientation situation of fiber reinforcement macromolecule composition board and the fiber inclusion rate are perpendicular and horizontal direction tensile strength and some correlation. Fiber orientation situation of tensile strength of 0 direction of composition board increased changelessly by aeolotropy in isotropy. Tensile strength of 90 direction that is isotropy and tensile strength of 0 direction that is aeolotropy agreed almost. Get into aeolotropy, the reinforcement rate of fiber decreased. When load interacts for width direction of reinforcement.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.186-191
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• 2004

we can say that the increasing range of the value of GMT Sheet's tensile strength in the direction of fiber orientation is getting wider as the fiber content increases. It shows that the value of GMT Sheet's tensile strength in the direction of fiber orientation 90 is similar with the value of pp's intensity when fiber orientation function is J= 0.7, regardless of the fiber content. Tensile strength of GMT Sheet is affected by the fiber orientation distribution more than by the fiber content.