• Composites Research
• /
• 제34권3호
• /
• pp.143-147
• /
• 2021

유리섬유 복합재료(GFRP) 내부 미세 박리에서 나타나는 테라헤르츠(THz) 중첩 신호의 FWHM 분석을 통한 미세 박리 검출 기술을 연구하였다. 테라헤르츠 시간영역 분광(THz-TDS) 시스템의 반사모드를 통해 유리섬유 복합재료 내부의 미세 박리 크기 별 THz 신호를 측정하였고, 미세 박리 위치에서 반사되어 검출되는 THz 중첩 신호의 Full Width Half Maximum (FWHM) 값을 추출하였다. 이후, 유리섬유 복합재료의 복소굴절률을 측정하여 미세 박리 크기에 따른 미세 박리 위치에서의 THz 중첩 신호 및 FWHM 값을 계산하여 비교하였다. 이론적으로 계산된 THz 중첩 신호로부터 미세 박리 크기와 중첩 신호에서의 FWHM 값의 상관관계를 도출하였으며, 미세 박리 위치에서의 THz 신호로부터 추출된 FWHM의 분석을 통해 미세 박리 크기를 예측할 수 있었다.

• Journal of the Optical Society of Korea
• /
• 제20권3호
• /
• pp.389-395
• /
• 2016

A Carbon Fiber Composite (CFC) framework was designed for a small lightweight space camera. According to the distribution characteristics of each optical element in the optical system, CFC (M40J) was chosen to accomplish the design of the framework. TC4 embedded parts were used to solve the low accuracy of the CFC framework interface problem. An integrated optimization method and the optimization strategy which combined a genetic global optimization algorithm with a downhill simplex local optimization algorithm were adopted to optimize the structure parameters of the framework. After optimization, the total weight of the CFC framework and the TC4 embedded parts is 15.6 kg, accounting for only 18.4% that of the camera. The first order frequency of the camera reaches 104.8 Hz. Finally, a mechanical environment test was performed, and the result demonstrates that the first order frequency of the camera is 102 Hz, which is consistent with the simulation result. It further verifies the rationality and correctness of the optimization result. The integrated optimization method mentioned in this paper can be applied to the structure design of other space cameras, which can greatly improve the structure design efficiency.

• 한국입자에어로졸학회지
• /
• 제10권2호
• /
• pp.45-51
• /
• 2014

Fine particle capture is facing a challenge since traditional filtration which relies on the combination of impaction, interception, diffusion has a limited efficiency for fine particle capture particularly in size from 0.1 to $0.5{\mu}m$. This paper reviewed the collection efficiency of above mechanisms, as well as magnetic mechanisms for ferromagnetic particles, and mainly studied the influencing factors of magnetic filtration. Filtration velocity, magnetic field intensity and fiber size were found to be the most important parameters for magnetic filtration.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
• /
• pp.119-122
• /
• 2004

A CPGFRP(Carbon Powder Glass Fiber Reinforced Plastics) sensor was fabricated for fine crack detection of structures. The electrical resistance of the sensor was measured on condition of various composition of carbon powders and thickness of bundle of glass fibers. The resistance was decreased as the increase of the content of carbon powders and the TEX of the glass fibers. In the case of loading on CPGFRP sensor, because inner crack was propagated, the part of percolation structures was disconnected. The sensor is superior to carbon fiber for the detecting ability of fine crack.

• Carbon letters
• /
• 제18권
• /
• pp.56-61
• /
• 2016

Cellulose fibers were stabilized by treatment with an electron-beam (E-beam). The properties of the stabilized fibers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The E-beam-stabilized cellulose fibers were carbonized in N₂ gas at 800℃ for 1 h, and their carbonization yields were measured. The structure of the cellulose fibers was determined to have changed to hemicellulose and cross-linked cellulose as a result of the E-beam stabilization. The hemicellulose decreased the initial decomposition temperature, and the cross-linked bonds increased the carbonization yield of the cellulose fibers. Increasing the absorbed E-beam dose to 1500 kGy increased the carbonization yield of the cellulose-based carbon fiber by 27.5% upon exposure compared to untreated cellulose fibers.

• 펄프종이기술
• /
• 제37권1호
• /
• pp.17-24
• /
• 2005

The increase of using low grade ace, the unsorted mixed grade, as fibrous raw materials for the packaging paper results in the increment of fine screen reject owing to the strong tendency to reduce the slot width. Since the most of screen reject consists of undispersed fiber flake, the suitable treatment of the flake could increase the yield of ace recycling and decrease the amount of solid waste. In this work, the novel method combined the mild mechanical treatment by using Tumbling pulper with the biological treatment was developed and applied to the wet strength flake and the fine screen tail line reject originated from a packaging paper mill. The results showed the new method could provide much better efficiency for the disintegration of undispersed flake and for the recovery of fiber from the rejects. The application of the laboratory scaled-Pack pulper showed the possible separation technique for mill application by fractioning effectively the fiber from the treated solid waste.

• 대한건축학회논문집:구조계
• /
• 제34권8호
• /
• pp.3-11
• /
• 2018

In this study, total nine R/C beams, designed by the PVA Fiber with ground granulated blast furnace slag and recycled fine aggregate were constructed and tested under monotonic loading. In the material development, micromechanics was adopted to properly select the optimized range of the composite based on steady-state cracking theory and experimental studies on the matrix and interracial properties. Experimental programs were carried out to improve and evaluate the structural performance of the test specimens: the load-displacement, the failure mode, the maximum strength, and ductility capacity were assessed. Test results showed that test specimens (BSPR-20, 40) was increased the maximum load carrying capacity by 3~6% and the ductility capacity by 9~14% in comparison with the standard specimen (BSS). And the specimens (BSPR-60, 80, 100) was decreased the maximum load carrying capacity by 0~4% and the ductility capacity by 79% in comparison with the standard specimen (BSS) respectively.

• 대한건축학회논문집:구조계
• /
• 제34권11호
• /
• pp.11-18
• /
• 2018

In this study, seven R/C beams, designed by the steel fiber with ground granulated blast furnace slag and recycled fine aggregate were constructed and tested under monotonic loading. In the material development, micromechanics was adopted to properly select the optimized range of the composite based on steady-state cracking theory and experimental studies on the matrix and interracial properties. Experimental programs were carried out to improve and evaluate the structural performance of the test specimens: the load-displacement, the failure mode, the maximum strength were assessed. Test results showed that test specimens (BSSR-20, 40, 60, 80) were increased the maximum load carrying capacity by 2~9% and the ductility capacity by 10~22% in comparison with the standard specimen (BSS) respectively. And the specimens (BSSR-100) was decreased the maximum load carrying capacity by 5% and the ductility capacity by 44% in comparison with the standard specimen (BSS) respectively.

• 한국터널지하공간학회 논문집
• /
• 제24권4호
• /
• pp.317-326
• /
• 2022

구조용 합성섬유는 작은 비중에 의한 반발률 감소, 지하수 및 해수에 의한 부식 발생의 우려가 없어 강섬유의 대체재로 구조용 합성섬유의 관심이 최근 높아지고 있다. 본 연구에서는 시멘트 복합체의 잔골재 조립률이 구조용 섬유의 인발강도 및 인발에너지에 미치는 영향을 평가하기 위한 실험연구를 수행하였다. 조립률 1.96, 2.69, 3.43인 잔골재로 시멘트 몰탈을 제작하였으며 구조용 합성섬유 1종(polypropylene), 강섬유 1종(hooked ends type)을 대상으로 단일섬유 dog bone shape 공시체를 제작하여 pull-out 실험을 수행하였다. 실험결과 구조용 합성섬유 공시체에서 시멘트 몰탈의 조립률이 증가할수록 인발강도 및 인발에너지가 증가함을 알 수 있었다. 구조용 합성섬유의 경우 시멘트 몰탈과 섬유 사이의 마찰력이 인발메커니즘의 중요인자로 시멘트 몰탈의 잔골재 조립률이 높아질수록 골재 입자가 크고 거칠어지며 섬유와 시멘트 몰탈 사이의 마찰력이 증가하여 섬유의 인발을 억제하기 때문으로 판단된다. 반면, 강섬유 공시체의 경우 시멘트 몰탈 조립률 증가에 따른 인발강도 및 인발에너지의 뚜렷한 경향성은 나타나지 않았다. 이는 강섬유 hooked ends 부분의 기계적 정착이 시멘트 복합체와 강섬유 사이의 마찰력과 비교하여 인발저항력에 미치는 영향이 더 크므로 시멘트 복합체의 잔골재 조립률 변화가 인발저항력에 상대적으로 적은 영향을 미치는 것으로 판단된다.

• 콘크리트학회논문집
• /
• 제14권2호
• /
• pp.190-198
• /
• 2002

본 연구에서는 폐 FRP(fiber reinforced plastics) 미분말을 잔골재 대용으로 치환한 폴리머 시멘트 모르타르의 물성을 조사하였다. 폴리머 혼화제로는 Styrene-Butadiene Rubber(SBR) 라텍스, Polyacrylic Ester(PAE) 에멀젼 및 Ethylene-Vinyl Acetate(EVA) 에멀젼을 사용하였다. 폐FRP 미분말의 치환율을 5~30 wt%, 폴리머 혼화제의 첨가량을 폴리머 시멘트비 5~20 wt%로 변화시켜 공시체를 제작하였다. 굳지 않은 폴리머 시멘트 모르타르의 물성, 경화 공시체의 흡수율, 내열수성 및 양생방법 에 따른 압축 및 휨강도를 측정하였다. 폐FRP 미분말을 치환ㆍ첨가한 폴리머 시멘트 모르타르의 압축 및 휨강도는 폐FRP 미분말의 치환량이 증가할수록 감소되었고, 폴리머 시멘트비가 증가할수록 증가되었다. 폴리머 혼화제로서 SBR 라텍스를 사용한 폴리머 시멘트 모르타르의 강도특성이 가장 우수하였고, 폴리머 시멘트 모르타르의 적정한 폴리머 시멘트비는 20wt%이었고, 폐FRP 미분말의 적정 치환량은 20wt%로 나타났다. 또한 폴리머 시멘트 모르타르는 가열양생에 의해 강도발현이 촉진되었다.