• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.564-573
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• 2001

The mechanical properties of short carbon/glass fiber reinforced polypropylene are experimentally measured as functions of fiber content and nozzle diameter. Also, these properties are compared with the survival rate of reinforced fibers and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber aspect ratio as well as fiber volume fraction is influenced by injection processing condition, the used materials and mold conditions such as diameter of nozzle, etc. In this study, the survival rate of fiber aspect ratio is investigated by nozzle size variations in injection/mold sides. It is found that the survival rate of glass fiber is higher that the survival rate of glass fiber is higher than that of carbon fiber. Both tensile modulus and strength of short-fiber reinforced polypropylene are improved s the fiber volume fraction and nozzle diameter are increased.

• Korean Journal of Optics and Photonics
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• v.32 no.2
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• pp.49-54
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• 2021

In this paper, we design and construct the equipment to manufacture large-diameter optical fiber end caps, which are the core parts of high-power fiber lasers, and we fabricate large-diameter optical fiber end caps using the home-made equipment. This equipment consists of a CO2 laser as a fusion-splice heat source, a precision stage assembly for transferring the position of a large-diameter optical fiber and an end cap, and a vision system used for alignment when the fusion splice is interlocked with the stage assembly. The output of the laser source is interlocked with the stage assembly to control the output, and the equipment is manufactured to align the polarization axis of the large-diameter polarization-maintaining optical fiber with the vision system. Optical fiber end caps were manufactured by laser fusion splicing of a large-diameter polarization-maintaining optical fiber with a clad diameter of 400 ㎛ and an end cap of 10×5×2 ㎣ (W×D×H) using home-made equipment. Signal-light insertion loss, polarization extinction ratio, and beam quality M2 of the fabricated large-diameter optical fiber end caps were measured to be 0.6%, 16.7 dB, and 1.21, respectively.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.21-28
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• 2000

Various man-made mineral fibers(MMMF) including refractory ceramic fiber(RCF) have been used widely in industries as insulation materials. The effect of fibrous dust on human health depends on fiber size, concentration (exposure level), and durability in biological system. Therefore, these parameters should be determined to evaluate accurately the potential risk of fibers on human health. The purpose of this study was to characterize the size of airborne fiber and the workers＇ exposure to airborne fibers in refractory ceramic fiber manufacturing and processing factories. Airborne fibers were collected on 25-mm mixed cellulose ester membrane filters at personal breathing zones, and analyzed by A and B counting rules of the National Institute for Occupational Safety and Health(NIOSH) Method # 7400. The average ratios of the fiber density by B rule to the fiber density by A rule was 0.84. This result indicates that the proportion of respirable fibers (<3 ${\mu}{\textrm}{m}$ diameter) in air samples was high. The average diameter and length of airborne fibers were 1.05${\mu}{\textrm}{m}$ and 35${\mu}{\textrm}{m}$, respectively. The average fiber concentrations (GM) of all personal samples was 0.26f/cc, and the average concentration was highest at blanket cutting and packing processes. The fifty seven percent of personal air samples was exceeded the proposed American Conference of Governmental Industrial Hygienists(ACGIH) Threshold Limit Value(TLV), i.e. 0.2 f/cc. It was concluded that the RCF industrial workers had the higher potential health risk due to small fiber diameter, long fiber length, and high exposure level to the airborne fibers.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.3
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• pp.401-405
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• 2002

An experiment was conducted to determine the effects of caponization on the growth performance, breast and thigh muscles physical properties and fiber diameter of the Pectoralis major and Gastrocnemius pars externa in Taiwan country chicken cockerels. Caponized birds were surgically altered at 10 weeks of age. Birds were fed grower and finisher diets ad libitum during an eighteen-week experimental period. The results indicated that the live weight and feed intake in the capons were significantly (p<0.05) higher and the shank length was significantly (p<0.05) longer than in intact birds. There were no significant (p>0.05) differences in feed conversion and mortality between two treatments at 28 weeks of age. Compared with intact birds, the capons had greater (p<0.05) tenderness in the breast and thigh muscles. Cohesion of the breast muscle in the capons was significantly (p<0.05) better than in the intact birds, but the thigh muscles were not significantly (p>0.05) affected. No treatment differences (p>0.05) were associated with cooking loss, muscle chewiness, and elasticity. The capons had a significantly (p<0.05) smaller fiber diameter in the Pectoralis major, but were not significantly (p>0.05) different in the fiber diameter of the Gastrocnemius pars externa. It is concluded that castration did not depress growth compared with the intact birds, but did improve muscle tenderness. This difference was most pronounced in the thigh muscles.

• Journal of the Korean Ceramic Society
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• v.17 no.2
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• pp.69-74
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• 1980

This study deals with the wire content, wire diameter, aspect ratio , it's arrangement of steel, wire fiber and the sorts of castable which affected the character of steel wire fiber reinformced refractory castable. Two kinds of alumina based refractory castables, one is for 1650℃ and the other is for 1800℃, and stainless steel which is SUS 304 type 0.25, 0.34 , 0.37 and 0.50m/min diameter were used respectively. Aspect ratio was adjusted to 50, 75, 100 and steel fiber content was also adjusted to 1-4wt% each. The results of the experiment were as follows : 1. At firing temperature around 1,000℃, MOR is increased with increasing wire content and aspect ratio with decreasing firing temperature, which depends on the Romualdi's Fiber Spacing Theory. But for calculation of the fiber spacing, Swamy equation is more a aplicable to the extensive fiber mixing conditions. However, the condition differs from the above at firing temperature around 1,350℃ ,because of the degradation of wire and the progress of sintering of castable. 2. Linear change is getting larger corresponding to the increase of wire content, and the spaling resistivity is increasing corresponding to the increase of wire content and to aspect ratio, and with decreasing wire diameter. 3. Firing shrinkage under load is getting greater as higher wire content, and the shrinkage of the test pieces which fiber is vertically oriented is getting greater than the test pieces which fiber is randomly oriented.

• Fibers and Polymers
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• v.6 no.3
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• pp.181-185
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• 2005

Silk fibroin (SF) nanofibers were prepared by electrospinning and their application as an enzyme immobilization support was attempted. By varying the concentration of SF dope solution the diameter of SF nanofiber was controlled. The SF nanofiber web had high capacity of enzyme loading, which reached to $5.6\;wt\%$. The activity of immobilized a-chymotrypsin (CT) on SF nanofiber was 8 times higher than that on silk fiber and it increased as the fiber diameter decreased. Sample SF8 (ca. 205 nm fiber diameter) has excellent stability at $25^{\circ}C$ by retaining more than $90\%$ of initial activity after 24 hours, while sample SF11 (ca. 320 nm fiber diameter) shows higher stability in ethanol, retaining more than $45\%$ of initial activity. The formation of multipoint attachment between enzyme and support might increase the stability of enzyme. From these results, it is expected that the electrospun SF nanofibers can be used as an excellent support for enzyme immobilization.

• Fibers and Polymers
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• v.3 no.4
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• pp.129-133
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• 2002

It is well known residual gum exists in degummed or rotted hemp fibers. Gum removal results in improvement in fiber fineness and the properties of the resultant hemp yams. However, it is not known what correlation if any exists between the residual gum content in retted hemp fibers and the fiber fineness, described in terms of fiber width in this paper. This study examined the mean width and coefficient of variation (CV) of fiber width of seventeen chemically rotted hemp samples with reference to residual gum content. The mean and CV of fiber width were obtained from an Optical fiber diameter analyser (OFDA 100). The linear regression analysis results show that the mean fiber width is directly proportional to the residual gum content. A slightly weaker linear correlation also exists between the coefficient of variation of fiber width and the residual gum content. The strong linear co-relation between the mean of fiber width and the residual gum content is a significant outcome, since testing for fiber width using the OFDA is a much simpler and quicker process than testing the residual gum content. Scanning Electron Microscopy (SEM) reinforces the OFDA findings. SEM micrographs show a flat ribbon like fiber cross-section hence the term \"fiber width\" is used instead of fiber diameter. Spectral differences in the untreated dry decorticated skin samples and chemically treated and subsequently carded samples indicate delignification. The peaks at $1370cm^{-1}$, $1325cm^{-1}$, $1733cm^{-1}$, and $1600cm^{-1}$ attributed to lignin in the untreated samples are missing from the spectra of the treated samples. The spectra of the treated samples are more amine-dominated with some of the OH character lost.cter lost.

• Journal of the Korean Society of Visualization
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• v.10 no.2
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• pp.14-19
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• 2012

An optical fiber probe system for measuring the local void fraction in the air-water two-phase flow was developed with a 1550 nm light source. Air was injected through a nozzle placed in the center of the bottom wall of a water-filled cylindrical tank. The optical fiber probe having a diameter of $125{\mu}m$ was sufficiently thin to resolve the air-water interface of the bubbly flows. To verify the performance of the optical fiber probe, the synchronized high speed visualization study using a high speed camera was carried out. Comparison between the optical signals and the instantaneous bubble diffraction images confirms that the optical fiber probe is very accurate to measure the void fraction in two-phase flows. The estimated bubble diameter and the rising velocity by the optical fiber probe have 1% and 5% of accuracy, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.743-749
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• 1999

Recently new rehabilitation techniques have been proposed with advanced composite materials like carbon fiber, aramid, glass fiber sheet and so forth. The purpose of this paper is to investigate the mechanical characteristics of reinforced concrete columns confined with carbon fiber sheet and evaluate the degree of their strengthening effect. For the test, the specimen size of column is 15cm$\times$15cm$\times$90cm reinforced with 4 number of main bars of 10 mm diameter, tied bars of 6 mm diameter and slenderness ratio 20. Columns were wrapped with carbon fiber sheet along the column length. It is necessary to make some assumption regarding the confinement of carbon fiber sheet to apply to reinforced concrete columns under concentric loads. The strength gain effect of columns confined with carbon fiber sheet could be predicted using the proposed equation.

• Textile Coloration and Finishing
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• v.18 no.2 s.87
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• pp.1-7
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• 2006

In order to prepare PAN nano fiber web, PAN/DMF solution was prepared and electrospun. The diameter of fiber was depended on the polymer concentration (7.5-15wt%) and the applied voltage (10-16kV). The average diameter of fiber increased with an increase of the polymer concentration and decreased with the applied voltage. At 7.5wt% concentration, many beads were found. So, we prepared a nano PAN fiber by electrospinning at concentration of 10wt% and 16kV. PAN fibers were reduced with litium aluminium hydride and the dyeability to acid dye was checked. The reduced nano PAN fiber showed much better dyeability compared with the reduced ordinary PAN fiber. It was considered that the increase of specific surface area have an important role in dyeing with acid dye.