• Magazine of the Korea Concrete Institute
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• v.2 no.3
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• pp.65-72
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• 1990

Theoretical expressions were dcrived for the numher of fibers per unit cross-sectional area in fiber reinforced concrete, with due consideration given to the effects of the surrounding boundaries. The number of fibers per unit cross-sectional area in steel fiber reinforced concrete was also measured experimentally for the specimens incorporating various volume fractions of fibers of different types. Statistical evaluation of the measured value was then performed in order to assess the differences in fiber concentration at different location on tbe cross section. Degree of reorientation of steel fibers in concrete occuring during vibration was examined by com¬paring the differences in the computed and measur'ed values of the number of fibers per unit cross-sectional area.

• Korean Journal of Food Science and Technology
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• v.7 no.4
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• pp.208-211
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• 1975

Round muscle of Korean cattle treated with papain were examined the tenderness relation by use of penetrometer which results were indicated as follows. 1. Measuring method of tenderness effect in bovine muscle was acknowledged that there are correlation by using penetrometer (p<.05) 2. Penetration value were also proportional increased according to increasing of enzyme concentration. 3. It was acknowledged as considerable difference in penetration value cf longitudinal and cross section against muscle fiber. 4. In the case of 0.05% enzyme addition, there are extremely high increasing rate of tenderness in longitudinal and cross section but it was not acknowledged as significant difference in 0.1% of enzyme concentration.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.385-389
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• 2003

To make high speed spindle system work properly, sensors with outstanding resolution and dynamic characteristics are essential. An optical fiber displacement sensor is based on simple principles. Electrical signal responds to the optical flux change due to the displacement change between a target and a sensor probe. In this paper, the performance of optical fiber displacement sensor has been investigated according to properties of optical fiber Firstly, optical loss has been measured before and after polishing optical fiber endface. Secondly, allowance of optical fiber bending has been tested. thirdly sensitivity and linear range of the sensor has been found out according to the shape of cross section of optical fiber.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.410-414
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• 2004

Under longitudinal loading continuous fiber reinforced metal matrix composite(MMC) have interpreted an outstanding performance. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In this study, elastic-plastic behavior of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber placement(square and hexagon) and fiber volume fractions were studied numerically. The interface was treated as three thin layer (with different properties) with a finite thickness between the fiber and the matrix. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

• Membrane Journal
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• v.29 no.6
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• pp.362-376
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• 2019

In this study, hydrophilic coating characteristics of PVDF [poly(vinylidene fluoride)] hollow fiber membranes with flower type cross-section prepared by thermally induced phase separation were studied. The hollow fiber used in this study was provided from PureEnvitech Co. Ltd., and the hydrophilic coating experiment was performed with different concentration and number of coating of PEBAX 1657, 2533 and 3533 block copolymer solution using a dip coating method. The hydrophilic coated hollow fiber membrane was characterized to scanning microscope and contact angle measurements to determine the degree of hydrophilization. As a result of SEM characterization, it was confirmed that the thickness of the coating layer increased as the coating concentration increased and the number of coatings increased. Contact angle of surface of hollow fibers decreased as the concentration of the coating solution increased and the number of coatings increased. Gas permeance of oxygen gas was measured for the application of the hydrophilized hollow fiber to Membrane Areated Biofilm Reactor. As a result of gas permeation test, it was confirmed that gas permeance decreased with increasing coating concentration and number of coatings, and the more hydrophilized hollow fiber coated with PEBAX 1657 showed lower gas permeance than those coated with PEBAX 2533 and 3533.

• Journal of the Korean Wood Science and Technology
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• v.16 no.1
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• pp.9-20
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• 1988

Lespedeza species have been widely used not only as plant resources for bark, leaves and honey, but also as erosion control materials. This study was carried out to investigate the structural and wood tiber characteristics in order to obtain basic information for the utilization of the wood. The wood structure was investigated for 10 selected species and the wood fiber, for the 5 selected species among Lespedeza species distributed all over the country. The following results were obtained. In the cross section, campylotropis showed ray diffuse porous wood, L. bicolor, L. cyrtobotrya, L. thunbergii var. intermedia, diffuse porous wood, and L. tomentella, L. angustifolioides. L. maritima, L. robusta, L. patentibicolor, ring porous wood. The maximum diameter of a single vessel ranged 66-123 ${\mu}$ in all species. Campylotropis showed the most number of vessels, L. angustifolioides, the least. The number of ray per mm ranged 7-22, Campylotropis showed the most number of rays, L. angustifolioides, the least. In the radial section the average length of vessel ranged 121-250 ${\mu}$ in all species. L. thunbergii var. intermedia showed the longest vessel, L. tomentella, the shortest. In tangential section the average width of the uniseriate ray ranged 9.2-14.7${\mu}$, that of the multiseriate ray, 19.2-42.1 ${\mu}$. The average height of the uniseriate ray ranged 143.0-1162.0 ${\mu}$. The width of fiber ranged 10.12-13.61 ${\mu}$, L. maximowiezii showed the narrowest tiber, L. thunbergii var. intermedia. the widest, the thickness of fiber wall ranged 2.93-3.71 ${\mu}$ in the five species. L. maximowiezii showed the most thin fiber wall, L. thunbergii var. intermedia, the thickest, L. cyrtobotrya showed the difference in the size of fiber between the shade and the sunny sites but L. maximowiezii showed no difference. There was significant difference in fiber length, fiber width and wall thickness between L. eyrtobotrya and L. maximowiezii.

• Textile Coloration and Finishing
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• v.28 no.3
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• pp.183-188
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• 2016

The uniformly dispersed p-Aramid chopped fiber in a variety of rubber was investigated. The cross section and surface properties in a variety of rubber were characterized by scanning electron microscopy(SEM), weight, tensile strength, cold resistance measurements. The 1mm p-Aramid chopped fiber better uniformly dispersed than the other p-Aramid chopped fiber. The p-Aramid of lmm chopped fiber showed excellent adhesion in rubber composite because of homogeneous dispersion. Consequently, the best 1mm chopped fiber and rubber improved the strength of the composite.

• Composites Research
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• v.19 no.1
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• pp.29-35
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• 2006

The avoidance of enemy's radar detection is very important issue in the modem electronic weapon system. Researchers have studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), 'C'-type shell and 'U'-type shell, were fabricated using fiber-reinforced composite materials and their radar cross section (RCS) were evaluated. The absorption layer was composed of glass fiber reinforced epoxy and nano size carbon-black, and the reflection layer was fabricated with carbon fiber reinforced epoxy. During their manufacturing process, undesired thermal deformation (so called spring-back) was observed. In order to reduce spring-back, the bending angle of mold was controlled by a series of experiments. The spring-back of parts fabricated by using compensated mold was predicted by finite element analysis (ANSYS). The RCS of RAS shells were measured by compact range and predicted by physical optics method. The measured RCS data was well matched with the predicted data.

• 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 Korean Society of Clothing and Textiles
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• v.34 no.11
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• pp.1889-1899
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• 2010

This study examines the preparation and characterization of Kenaf/Starch bio-composites used as filler and a matrix. Kenaf was cultivated in Chung-ju in Korea, and the Kenaf/Starch bio-composites were prepared under various conditions of kenaf fiber length (1-5 centimeters); the content of Kenaf fiber was 10%, 20%, 30%, and 40%, and the number of composite layers (one-four). Depending on the formation conditions of Kenaf/Starch composites, the physical properties such as tensile strength, elongation, and the young modulus of the Kenaf/Starch composites were measured. In addition, we measured the SEM cross-section images in order to investigate the interfacial adhesion properties of fractured surfaces. As a result, the tensile strength and elongation of the Kenaf/Starch composites were highest in the molding conditions of a hot press at $120^{\circ}C$, 3000PSI of pressure, and for 30 minute periods. The result of measuring the physical properties of the composites manufactured by varying the content of Kenaf fiber when the content of Kenaf fiber was 30% as well the physical properties of the Kenaf/Starch composite was found desirable. It was found that the physical properties improved with more overlapped layers in the composites manufactured by varying the number of overlapped layers. Through the measuring of the SEM cross-section images, we found that the interfacial adhesion state between the filler and matrix of Kenaf/Starch composite greatly affects the physical properties.