• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6534-6541
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• 2013

The aim of this study was to develop a fiber-reinforced asphalt mixture that was designed to do the following: 1) address fatigue cracks, which is a major source of damage; and 2) increase the rutting resistance. This study reports the effects of the aggregate mixture design that incorporates a dumbbell-shaped fiber. An experiment was carried out to measure the unit weights and unit weight ratios between the mixture that was compacted and the one that was not. A method to substitute a specific aggregate mixture with the dumbbell-shaped fiber was confirmed using the volume concept according to the Bailey method. The results showed that the weight of the PCS aggregate mixture that need to be replaced was 11.88g when a 0.3% reinforcing fiber was added to the 1950g mixture.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.28-33
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• 2017

SiC fiber can be used up to $1800^{\circ}C$ in both inert and air atmosphere without any problems such as melting and oxidation. SiC fibers can be applied to dust filtering processes as a bag filter at a high temperature above $700^{\circ}C$, which is far beyond the temperature range of currently available industrial bag filter. However the studies for the degradation of SiC fibers were still lacked in the harsh environment of steel industries and thermoelectric power plants. In this study, SiC fibers were reacted with steel dust and thermal power plant dust at a high temperature of $500^{\circ}C$ or higher, and the degraded shape of the fiber surface was observed by SEM. Also the degree of oxygen diffusion on the surface and inside of SiC fiber was analyzed by EDS.

• Polymer(Korea)
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• v.30 no.2
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• pp.175-181
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• 2006

Hybrid process of thermally-induced phase separation and stretching was developed for the preparation of microporous polypropylene hollow fiber membranes. Precursor for stretching was prepared by using soybean oil as a diluent and benzoic acid as a nucleating agent far the sphenlite control and it was stretched far the micrporous hollow fiber membrane. The effects of stretching ratio and deformation rate for stretching process were investigated. Increase of stretching ratio resulted in the greater pore size with nonuniform size distribution. Higher deformation rate also increaser the pore size with uniform size distribution. Stretching ratio was closely related with the orientation of polymer chain and increased the mechanical strength of the fiber. Increase of deformation rate had little effects on the orientation of crystalline phase, and decreased the orientation of amorphous phase which caused the decrease of tensile strength of the fiber and broke the micro-fibrils connecting spherulites to form a circular pore shape.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.557-560
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• 2008

Fiber reinforcement has been being widely used in concrete to enhance the mechanical properties and to reduce the micro-cracking caused by plastic and drying shrinkage. While researches has been focused on the benefits of fiber reinforcement, the properties of fiber reinforced concrete are strongly dependent on the type, shape and the amount of fibers in concrete. In this study, the resistance of nylon fiber reinforced concrete against the chloride ion penetration was experimentally observed by NT Build 492. The test results showed that the addition of nylon fiber has little effect on the change of the resistivity of concrete to the chloride ion penetration.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.5
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• pp.711-720
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• 2009

Leaf fibers have many good properties; they are strong, long, cheap, abundant and bio-degradable. Since they, however, contain a great quantity of non-cellulose components, they have been used for the materials of mats, ropes, bags and nets rather than those of clothing. In this study, we investigated the characteristics of leaf fibers in order to promote the use of leaf fibers for the materials of clothing as well as develop the high value-added textile fibers. Leaf fiber plants including New Zealand Flax, Henequen and Banana plant, which have various nature and shape, were used. New Zealand Flax and Henequen leaves were cut from lower part of plants. Banana leaves and pseudo-stems were peeled and cut from the stem of Banana plants. First, the thin outer skins like film of leaves, veins and stems were removed before retting. The chemical retting had been processed for 1hour, at 100 in 0.4% $H_2SO_4$ aqueous solution(liquid ratio 50:1). Then, the retted leaf fibers had been soaked for 1hour, at room temperature in 0.5% NaClO solution(v/v) to remove the miscellaneous materials. We investigated the physical characteristics of three leaf fibers including the transversal and longitudinal morphology, the contents(%) of pectin, lignin and hemicellulose, the length and diameter of fibers, the tensile strength of the fiber bundles, and the fiber crystallinity and the moisture regain(%). The lengths of fiber from three leaf fibers were similar to their leaf lengths. The fiber bundles were composed of the cellulose paralleled to the fiber axis and the non-cellulose intersecting at right angle with the fiber axis. The diameters of New Zealand Flax, Henequen and Banana fibers were $25.13{\mu}m$, $18.16{\mu}m$ and $14.01{\mu}m$, respectively and their tensile strengths were 19.40 Mpa, 32.16 Mpa and 8.45 Mpa, respective. The non-cellulose contents of three leaf fibers were relatively as high as 40%. If the non-cellulose contents of leaf fibers might be controlled, leaf fibers could be used for the materials of textile fiber, non-wovens and Korean traditional paper, Hanjee.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.3
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• pp.179-185
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• 1992

The shape memory effect results from the martensite transfomation of each individual grain. Thus it is necessary to study the texture and its variation. In this study the change of texture during thermal cycling and it's effect on shape memory ability are investigated. The major component of the rolling texture in the parent phase is identified (001) [110], and minor components are (112) [110], (111) [112], {hkl}<100> fiber texture is developed at $45^{\circ}$ from rolling direction. In the case of martensite phase, it is estimated that the major component is (011) [100] and the minor components are (105) [501], (010) [101] and (100) [001]. According to thermal cycling. severity of texture, especially (001) [110] component in parent phase and (011) [100] component in martensite phase are increased. The shape memory ability is increased with increase of thermal cycles and also increased as the direction of specimen approach to $45^{\circ}$ from rolling direction. After first thermal cycling the temperature of transformation can be define clearly and Ms and As are raised by thermal cycling.

• 대한공업교육학회지
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• v.34 no.2
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• pp.331-345
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• 2009

In this research Sagnac interferometer three different types of mandrel are suggested and this fiber optic sensor is using in monitoring of electric transformer. Vibration characteristics of those mandrels were analyzed and finally more sensitivity mandrel are suggested. Three different mandrels using in fiber optic sensor are hollow cylinder with outer bump, pure hollow cylinder, hollow cylinder with inner bump. Natural frequencies and mode shapes are investigated using finite element method. Mode shape are considered at the frequency range from 2 kHz to 20 kHz. Fundamental dimensions of the hollow cylinder type's mandrel are 30 mm in outer diameter, 50 mm in length, 1 mm in cylinder thickness, $2mm{\times}2mm$ in bump size. Based on the finite element results, when the outer acoustic frequency is near 11 kHz outer bump type and hollow cylinder can get higher sensitivity. Near 17 kHz outer bump and inner bump mandrel can get higher sensitivity. Near 20 kHz hollow cylinder and inner bump mandrel is useful. This results can be applied to design of fiber optic sensor using in monitoring the electrical transformer. Several MHz of outer acoustic frequency can be easily detected using more sensitive mandrel in pursuing expand this technique.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.94-103
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• 2018

The purpose of designing composite lattice structure which applied to launching vehicle and tactical missile body is to minimize the thickness and weight for applied load. It is usually made of carbon fiber; fabricating with filament winding process over silicon mold, and provided with a window opening for inspection purpose if necessary. In this paper compression test is conducted without window opening in lattice structure and preliminary FEA is carried out to confirm its accuracy. And then FEA is performed for the case of window opening to evaluate the soundness and the safety factor of the structure. We have calculated for two kinds of window shape; rectangular one and hexagonal one. And we have calculated safety factors of the lattice structure with window opening in every case based on failure strength of rib and knot with varying the thickness and location of the window for hexagonal shape. Through our investigation, we have found out the followings; (1) the hexagonal shaped window is shown higher safety factor than rectangular one, (2) a window in a certain location is shown higher safety factor than others, (3) although the soundness of window structure is improved as increasing its thickness, a window of a certain thickness is shown higher safety factor than others because of stress concentration.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.634-641
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• 2001

Shape memory alloy has been used to improve the tensile strength of composite by the occurrence of compressive residual stress in matrix using its shape memory effect. In order to fabricate shape memory alloy composite, TiNi alloy and A16061 were used as reinforcing material and mix, respectively. In this study, TiNi/A16061 shape memory alloy composite was made by using hot press method. However, the specimen fabricated by this method had the bonding problem at the boundary between TiNi fiber and Al matrix when the load was applied to it. A cold rolling was imposed to the specimen to improve the bonding effect. It was found that tensile strength of specimen subjected to cold rolling was more increased than that of specimen which did not underwent cold rolling. In addition, acoustic emission technique was used to quantify the microscopic damage behavior of cold rolled TiNi/A16061 shape memory alloy composite at high temperature.

• Journal of the Korean Wood Science and Technology
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• v.44 no.4
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• pp.571-588
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• 2016

Eucalyptus pellita F. Muell is one of pulp woods that is being developed through breeding plantation programs in Indonesia. The research aimed at exploring the chemical and morphological characteristics of fiber, and to determine the rank of plus trees from 4 provenances based on the suitability for pulps. The materials included the plus trees of E. pellita (9 years) from the 2nd generation of progeny tests in Pelaihari, South Borneo. Wood properties under investigation included the chemical properties and morphological fiber characteristics (fiber dimensions and its derived properties). In the present study, data were analyzed using descriptive statistic, Analytic Hierarchy Process (AHP) and Pearson's correlation. Results showed that the chemical properties of E. pellita, i.e. the contents of ethanol-toluene extractives, hot water soluble extractives, holocellulose, alphacelullose, and lignin were $3.08{\pm}1.00%$, $1.41{\pm}0.38%$, $75.26{\pm}2.58%$, $49.02{\pm}2.88%$, and $29.49{\pm}1.86%$, respectively. The average values of wood fiber morphology were $1.02{\pm}0.08$ mm (fiber length), $13.25{\pm}1.64{\mu}m$ (fiber diameter), of $6.94{\pm}1.70{\mu}m$ (lumen diameter), $3.15{\pm}0.52{\mu}m$ (fiber wall thickness), $0.97{\pm}0.30$ (Runkel ratio), $0.57{\pm}0.10$ (Luce's shape factor), $78.21{\pm}10.34$ (slenderness ratio) and $130.91{\pm}33.77{\times}10^3{\mu}m^3$ (solids factor). The AHP scoring rank indicated that the best individuals were 28.4.3.28 (Kiriwo Utara), 12.1.5.28 (North Kiriwo), 19.11.5.45 (Serisa Village), 3.8.4.9 (South Kiriwo), and 6.6.3.15 (South Kiriwo). Pearson correlation analysis showed significant correlations between the levels of fiber length with alpha-cellulose content (r = 0.39) as well as the fiber length with ethanol-toluene extractive contents (r = -0.41).