• 비파괴검사학회지
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• 제25권6호
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• pp.451-458
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• 2005

The effects of fiber orientation on acoustic emission(AE) characteristics have been studied for various composite laminates. Reflection and transmission optical microscopy were used to investigate the damage zone of specimens. AE signals were classified through short time Fourier transform(STFT) as different types: AE signals with a high intensity and high frequency band were due to fiber fracture, while weak AE signals with a low frequency band were due to matrix cracking and/or interfacial cracking. Characteristic feature in the rate of hit-events having high amplitudes showed a procedure of fiber breakages, which expressed the characteristic fracture processes of notched fiber-reinforced plastics with different fiber orientations. As a consequence, the behavior of fracture in the continuous composite laminates could be monitored through nondestructive evaluation(NDE) using the AE technique.

• 대한기계학회논문집
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• 제17권7호
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• pp.1740-1750
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• 1993

The aluminar short fiber reinforced composite materials for hot extrusion were fabricated by semi-solid stirring method, and extruded at extrusion temperature $400^{\circ}C$ with various extrusion ratio. The hot extrusion load of volume fraction 15% metal matrix composites and base alloy Al7075 has been compared. The fiber length distribution, fiber breakage and fiber orientation are investiged to know the fiber behaviour in before and after hot extrusion. The tensile strength of the hot extruded billet are experimentally determined for different of extrusion ratios, and compared with theorically calculated strength.

• 펄프종이기술
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• 제33권4호
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• pp.35-41
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• 2001

A newly developed functional fiber for textile, Tencel, which is known to have some advantages over wood fiber such as fibrillation, absorbency and so on, was examined to see the possibility of a raw material for hanji. Hanji was manufactured by the conventional handmade method using Tencel of three different fiber lengths with three different levels of mixing ratio of Tencel and paper mullberry fiber, and their physical and calligraphic properties were evaluated and compared with one another. It was needed to develop more efficient beating methods than conventional one such as valley beating for Tencel to be used effectively as a raw material for hanji. It was found out by image analysis that the calligraphic properties of hanji could be improved by mixing of 10 to 20% of Tencel of relatively short-length fiber with paper mulberry.

• The Journal of Advanced Prosthodontics
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• 제6권1호
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• pp.60-65
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• 2014

Teeth that have short clinical crown, which are not alone enough to support the definitive restoration can be best treated using the post and core system. The advantages of fiber post over conventional metallic post materials have led to its wide acceptance. In addition to that the combination of aesthetic and mechanical benefits of fiber post has provided it with a rise in the field of dentistry. Also the results obtained from some clinical trials have encouraged the clinicians to use the fiber posts confidently. Fiber posts are manufactured from pre-stretched fibers impregnated within a resin matrix. The fibers could that be of carbon, glass/silica, and quartz, whereas Epoxy and bis-GMA are the most widely used resin bases. But recently studies are also found to be going on for polyimide as possible material for the fiber post resin base as a substitute for the conventional materials.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.669-672
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• 2006

Recently, large efforts have been made to develop and understand the behavior of Fiber Reinforced Concrete. As in the static loading cases, many researches have been done. However, a few studies have been conducted in cyclic behaviors of FRC. The main objective of the present work is to investigate the cyclic behavior of fiber reinforced concrete with theoretical method. First, cyclic constitutive relations which describe the crack bridging stress considering non-uniform interfacial bond degradation in short randomly oriented fiber reinforced matrix composites under uniaxial cyclic tension were considered. A cyclic degradation model of single fiber based on micromechanics also taken into consideration. As an example, fatigue analysis for ECC with PVA fiber was conducted using proposed equations. Results shows that proposed method can establish a basis for analyzing cyclic behavior of fiber reinforced composites.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.1-16
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• 2015

Due to design codes and regulations and the variety of building plans in Turkey, it is very often seen that band-type windows are left for ventilation and lightening of the basements of buildings which are used for various purposes such as workplaces and storage. Therefore when the necessary support measures cannot be given, short columns are subjected to very high shear forces and so damage occurs. One of the precautions to avoid the damage of short column mechanisms in buildings where band-type windows are in the basement is to strengthen the short columns with fiber reinforced polymer (FRP). In this study, the effect of the FRP retrofitting process of the short columns around band-windowed structures, which are found especially in basement areas, is analyzed in accordance with Turkish Seismic Code 2007 (TSC 2007). Three different models which are bare frame, frame with short columns and retrofitted short columns with FRP, are created and analyzed according to TSC 2007 performance analysis methods to understand the effects of band windows in basements and the effect of FRP retrofitting.

• 한국주조공학회지
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• 제13권1호
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• pp.62-70
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• 1993

This study presents the effect of applied pressure on the preform deformation during squeeze casting of $Al_2O_3$ short fiber reinforced aluminum alloy (AC8A) metal matrix composites. A preliminary model based on the general beam theory is suggested for the prediction of the preform deformation. Two different commercially available $Al_2O_3$ short fiber (Saffil, Kaowool) were used to study the influence of the fibers on the microstructure and mechanical properties of the squeeze cast $Al/Al_2O_3$ composites. The composites were fabricated with the applied pressure of 75 MPa which was found to be the optimum condition for the squeeze casting of the composites in this study. For the amorphous Kaowool fiber, hard crystalline Mullite phase was formed with heat treatment. Both of amorphous and the crystallized Kaowool fibers were used to fabricate $Al/Al_2O_3$ composites. Microhardness of crystallized Kaowool fiber revealed higher than that of the amorphous Kaowool fiber in the squeeze cast composites. It was also found that the wear resistance of Kaowool fiber reinforced composites increased with the amount of Mullite.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.394-395
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• 2003

絲(bundle)와 구성섬유(fiber)간의 인장물성 관계를 규명하기 위한 연구는 오래전부터 계속되어 왔다[1-4]. 그러나, 과거의 연구들은 주로 면사와 같은 단섬유(short staple)를 중심으로 이루어졌으며, 합성섬유와 같은 장섬유(continuous filament)의 경우 불균제가 작다는 이유로 스테이플에 비해 소홀시 되어왔다. 조사에 의하면 합성섬유도 생산국 및 제조사에 따른 絲의 인장물성은 큰 차이를 나타내므로[5], 필라멘트의 인장물성에 대한 연구의 중요성도 간과할 수 없다. (중략)

• 한국주조공학회지
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• 제27권6호
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• pp.258-262
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• 2007

단섬유강화 고분자 복합재료의 고온압축 프레스 성형 시 유리섬유의 유동을 지배하는 인자인 유리섬유와 모재의 유동성에 관하여 연구하기 위하여 ?h트 스트랜드의 교차각도를 $30^{\circ},\;45^{\circ},\;60^{\circ}$로 배향하여 모재와 적층시킨 다음 열압축프레스를 사용하여 1차로 시트를 제작하고, 이 제작된 시트를 가열로로 가열하여 열압축프레스로 2차 고온압축 프레스 성형한다. 여기서, 압축속도와 압축비를 변화시켰을 때 발생되는 유리섬유의 배향에 관한 실험결과를 고찰한다.

• 한국광학회지
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• 제4권4호
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• pp.487-492
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• 1993

편광유지 광섬유를 이용하여 자이로스코프를 구성하였다. 전체 시스템의 총 광 손실은 약 25dB였으며, 지구자전속도를 기준으로 하여 장기 drift와 단기 잡음을 측정하였다. 장기 drift는 온도변화와 밀접한 관계가 있었으며 약 $3^{\circ}/hr$ 정도의 값을 얻었고, 단기 근 잡음은 약 $0.6^{\circ}/hr/{\sqrt{Hz}}$의 값을 나타내었다.