• Textile Coloration and Finishing
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• v.21 no.6
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• pp.22-28
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• 2009

Oil-absorbable nonwovens were produced by melt-blown processing of polypropylene chips. The melt-blown processing conditions, such as air pressure, and gear pump speed, DCD. In this study, these three factors were chosen to produce samples. Experimental array and variance analysis of the design of experiment were used to increase the field repeatability and universality. The effect of the factors on oil absorption properties of melt-blown nonwoven fabric such as oil absorbency were evaluated. As a result, the fiber diameter decreased as gearpump speed decreased or air pressure increased. The oil absorbency increased as air pressure increased or gearpump speed decreased and with the DCD increasing the oil absorbency significantly increased.

• Korean journal of food and cookery science
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• v.19 no.1
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• pp.79-82
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• 2003

Volatile compounds in Elsholtzia splendens were extracted by solid phase microextraction (SPME). Two kinds of SPME fiber, carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane (PDMS) were used to determine the selectivity of the fibers to the different flavor compounds present in the Elsholtzia splendens. Identification of volatile compounds was based on the linear retention indices (RI) and the comparison of their mass spectra with those of on-computer library. Thirty compounds were identified in the volatile compounds extracted by CAR/PDMS fiber, including 1 aldehyde, 5 alcohols, 3 hydrocarbons, 17 terpene hydrocarbons, 3 ketones and 1 miscellaneous. And 5 alcohols, 3 hydrocarbons, 18 terpene hydrocarbons, 3 ketones and 2 miscellaneouses were identified in PDMS fiber. These results suggested that the selectivity of PDMS fiber was similar to that of CAR/PDMS fiber in Elsholtzia splendens. The major volatile compounds were naginataketone and elsholtziaketone in Elsholtzia splendens.

• The Journal of Engineering Research
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• v.2 no.1
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• pp.103-111
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• 1997

EDFA (Erbium Doped Fiber Amplifier) is widely used to compensate the loss in fiber optic transmission system. The characteristics of EDFA are investigated by analyzing the mechanism amplifying the optical power of an input with several factors to obtain the criteria for designing EDFA. When it is used in fiber optic transmission system, signal to noise characteristics in the receiver is deteriorated due to the spontaneous emission noise of EDFA. We investigate the operating conditions of EDFA to reduce BER (Bit Error Rate).

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.135-142
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• 2001

This study discusses frequency analysis based on the frequency spectrum and process characterization in orthogonal cutting of Fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester(GFRP) was used as workpiece The present method employs a force sensor and the signals from the sensor are processed using the fast Fourier transform(FFT) technique. The experimental correlations between the different chip formation mechanisms and power spectrum me established. Effects of fiber orientation, cutting parameters and tool geometry on the cutting mechanisms me also discussed.

• Steel and Composite Structures
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• v.7 no.5
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• pp.355-376
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• 2007

The purpose of this study is to predict and investigate the time-dependent creep behavior of composite materials. For this, firstly the evaluation method for the modulus of elasticity of whole fiber and matrix is presented from the limited information on fiber volume fraction using the singular value decomposition method. Then, the effects of fiber volume fraction on modulus of elasticity of GFRP are verified. Also, as a creep model, the nonlinear curve fitting method based on the Marquardt algorithm is proposed. Using the existing Findley's power creep model and the proposed creep model, the effect of fiber volume fraction on the nonlinear creep behavior of composite materials is verified. Then, for the time-dependent analysis of a composite material subjected to uniaxial tension and simple shear loadings, a user-provided subroutine UMAT is developed to run within ABAQUS. Finally, the creep behavior of center loaded beam structure is investigated using the Hermitian beam elements with shear deformation effect and with time-dependent elastic and shear moduli.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.521-522
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• 2006

Thermally expanded core fiber (TEC-fiber) Bragg gratings have been fabricated and their transmission spectrums have been analyzed. The measured spectrum shows the characteristic peak splitting caused by the grating pair formed over the expanded section that has the effective index axial distribution, which could be employed for high resolution fiber sensors. An analysis on the spectrum can also give useful informations on the effective index profile of the TEC-fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.713-716
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• 2006

The main purpose of this research was to enhance the durability in both the design and construction of dams. Especially, in case of rockfill dams, the durability of tunnel concrete in a concrete-faced rockfill dam(CFRD) is achieved by optimizing the fly ash replacement for cement and application of steel fiber. The effect on durability and thermal property corresponding to the increasing replacement of fly ash and application of steel fiber was evaluated, and the optimum value of fly ash replacement and steel fiber application was recommended. The results show that 15% of fly ash replacement and $20kg/m^3$ of steel fiber application was found to be an optimum level and demonstrated excellent performance in durability and thermal property.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.53-57
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• 2004

The stabilization of fiber-optic current sensor has been achieved by using a broadband light source and a Faraday Rotator Glass fiber sensor coil. The very low Photo-elastic constant of the fiber suppressed output variations within ${\pm}0.4[%]$ when mechanical disturbance was applied to the sensor coil. Noise characteristics, with different light sources, have also been analyzed, which experimentally proved that the wider bandwidth source showed the better noise performance.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.9-16
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• 2012

In this study, the effect of metakaoline and silica fume on the bond performances of structural polyvinyl alcohol (PVA) fiber in cement mortar, including bond strength, interface toughness, and microstructure analysis are presented. Metakaoline and silica fume contents ranging from 0 % to 15 % are used in the mix proportions. Pullout tests are conducted to measure the bond performance of PVA fiber from cement mortar. Test results showed the incorporation of metakaoline and silica fume can effectively enhance the PVA fiber-cement mortar interfacial properties. Bond strength and interface toughness increased with metakaoline and silica fume content up to 10 % in cement mortar and decreased when the metakaoline and silica fume content reached 15 %. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results.

• Steel and Composite Structures
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• v.30 no.4
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• pp.327-336
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• 2019

This paper presents geometrically nonlinear behavior of cracked fiber reinforced composite beams by using finite element method with and the first shear beam theory. Total Lagrangian approach is used in the nonlinear kinematic relations. The crack model is considered as the rotational spring which separate into two parts of beams. In the nonlinear solution, the Newton-Raphson is used with incremental displacement. The effects of fibre orientation angles, the volume fraction, the crack depth and locations of the cracks on the geometrically nonlinear deflections of fiber reinforced composite are examined and discussed in numerical results. Also, the difference between geometrically linear and nonlinear solutions for the cracked fiber reinforced composite beams.