• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.17-26
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• 2020

This study examined the structural effectiveness of the unbonded technique originally developed for seismic strengthening of unreinforced masonry walls on the basis of the prestressed steel bars and glass fiber (GF) grids. The masonry walls were strengthened by using individual steel bars or GF grids and their combination. Test results showed that the proposed technique was favorable in enhancing the strength, stiffness, and ductility of the masonry walls. When compared with the lateral load capacity, stiffness at the ascending branch of the lateral load-displacement curve, and energy dissipation capacity of the unstrengthened control wall, the increasing ratios were 110%, 120%, and 360%, respectively, for the walls strengthened with the individual GF grids, 140%, 130%, and 510%, respectively, for the walls strengthened with the individual steel bars, and 160%, 130%, and 840%, respectively, for the walls strengthened with the combination of steel bars and GF grids. The measured lateral load capacities of masonry walls strengthened with the developed technique were in relatively good agreement with the predictions by the equations proposed by Yang et al. Overall, the developed technique is quite promising in enhancing the seismic performance of unreinforced masonry walls.

• Composites Research
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• v.12 no.6
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• pp.8-14
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• 1999

This research is focused on the investigation of impact strength and the microscopic observation of material behavior of glass fiber reinforced polypropylene in solid phase forming. The fiber weight per-centage of the composite materials was 20%, 30% and 40%. The solid-phase formed specimens were pre-strained to 10%,20%. and 30% strain levels. The forming temperatures of specimens were $100^{\circ}C$, $125^{\circ}C$ and $150^{\circ}C$. Izod impact test was performed with unnotched specimens. With increasing the glass fiber content ; the impact strength was increased.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.219-226
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• 1994

In the comparison result of residual strain calculated from the load-strain curve under the repeated loading cycles, it was found that the larger the laminates is, the larger the stiffness of GFRP pipes under fatigue load is. This phenomenon is true until the fatigue failure. According to the S-N curves drawn by the regression analysis on the fatigue test results, the fatigue strength for percentage of the static ultimate strength increases by increasing the laminates of GFRP pipes. The fatigue strength for 2, 000, 000 repeated loading cycles In GFRP pipes with the laminates varing 15, 25, 35 shows 75.2%, 79.5%, 84.2% on the static ultimate strength, respectively.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.35-42
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• 2003

This study was conducted to estimate peeling and vapor adsorption properties made with fabric glass fiber reinforced laminated timber according to our earlier report(Jung et al., 2002). In adsorption peeling test, three all types solid wood were not appeared the peeling. However, solid wood appeared to the peeling in boiling peeling test except for control wood. Vapor adsorption test was performed at 40℃, 90% relative humidity for 48 hours. Cross sections were not different all solid wood. Radial section and tangential section with glass fiber were delayed vapor adsorption compared to control wood. In anisotropy of vapor adsorption, solid wood with glass fiber were small values.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.153-159
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• 2007

This paper is experimental investigation for failure characteristics and performance of a RC beams strengthened with GFSP which were developed for improvement of the early debonding problems in the externally bonded FRP systems. To represent damages and load conditions of the existing beam, pre-cracks and repeating loads are adopted for experimental parameters. In this experiment, it is confirmed that strengthening with GFSP is a very effective strengthening method for an increase in strength, a decrease in deflection, a control of the crack. But it shown that the design of the beams to be strengthened with GFSP should be consider a brittle behavior of the grass fiber on the flexural capacity.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.44-48
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• 1999

섬유 강화 고분자 복합재료에서 강화재인 섬유와 매트릭스의 계면은 복합재료의 물성에 지대한 영향을 미친다. 섬유와 매트릭스의 물성 차이 즉, 탄성율, 열팽창 계수, 경화시의 수축, 결정화도 등의 차이뿐만 아니라 하중이 가해질 때 응력 집중 (stress concentration) 현상이 계면에서 일어난다[1]. 유리섬유를 강화재로 사용한 복합재료에서 유리섬유는 표면이 hydroxyl기로 덮여 있기 때문에 친수성이 매우 크고 또한 마찰이나 정전기에 의해 손상을 받기 쉬운 단점이 있다. 따라서 매트릭스 수지와의 계면 접착력을 향상시키고 제조 공정 중에 섬유를 마찰이나 정전기로부터 보호하기 위한 처리가 필요하며 이들 "sizing" 이라고 한다[2,3].고 한다[2,3].

• Korean Journal of Materials Research
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• v.7 no.5
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• pp.434-443
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• 1997

유리섬유와 에폭시 수지와의 계면전단강도에 미치는 수분흡수, 섬유직경 및 섬유의표면상태 등의 영향을 검토하기 위해서 two fiber fragmentation 시험법을 사용하였다. 그리고 유리섬유/에폭시 수지의 일방향 복합재료에서 수분흡수가 복합재료의 기계적 성질에 미치는 영향에 대해서도 검토하였다. 그 결과, two fiber fragmentation시험에서 계면전단강도는 수분흡수량 및 섬유직경이 클수록 작게 나타났으며, sizing한 것이 desizing한 것보다 크게 나타났다. 또 수분흡습에 의해 감소되었던 계면전단강도는 건조에 의해서 처음의 값의 약 50-60%까지 회복됨을 나타내었다. 그리고 일방향 복합재료의 인장강도는 수분흡수량이 증가함에 따라 현저히 감소함을 보였다.

• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.13-19
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• 2004

The major distress types in the domestic asphalt pavement are fatigue cracking, reflection cracking, thermal cracking, and rutting. To decrease the pavement distress by reinforcing asphalt pavement with reinforcement interlayer in geosynthetics to the traditional pavement systems can improve these problems. This study conducted laboratory test with asphalt pavement reinforced by glass fiber sheet to fix systematically geosynthetic asphalt pavement system. Laboratory tests like wheel tracking test and crack resistance test are conducted to analyze the controlling effect of glass fiber sheet on cracking and rutting of asphalt pavement.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.439-448
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• 1996

The possibility of application or the transparent BK10 glass fiber/PMMA composites as a temperature-or wavelength-sensors was studied. Measurement of diameter and refractive index for glass fibers to be reinforced to PMMA as a function of drawing speed and temperature was done and the appropriate coating methods and solvent for coupling agent was researched. $T_{max%}$ value at which the maximum transmission for the composites occurs could be controlled to be in $31~50^{\circ}C$ by the processing factors such as fiber diameter, fiber vol%, molecular wt. of PMMA. Furthermore, with different wavelength other than 589.3 nm, the $T_{max%}$ value could be controlled to be in $35~55^{\circ}C$. For the sensibility of wavelength for the composites, there was not a wavelength ($\lamda_{max%}$) showing maximum transmission.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.203-209
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• 2010

In this study, the fatigue characteristics and life of a woven glass fabric/epoxy laminate composite applied to railway vehicles was evaluated. The fatigue test was conducted using a tension-tension load with a stress ratio R of 0.1 and frequency of 5 Hz. Two types of woven glass fabric/epoxy laminate composite was used in the fatigue test: with and without carbon/epoxy ply reinforcement. In addition, the fatigue life of the woven glass fabric/epoxy laminate composite was compared with that of aluminum 6005, which is used in the car body and underframe structures of railway vehicles. The test results showed that the failure strength and life of the woven glass fabric/epoxy laminate composite reinforced with three carbon/epoxy plies had a remarkable improvement compared with that of the bare specimen without reinforcement.