• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.2
• /
• pp.124-130
• /
• 2014

In a mass manufacturing system of optical fibers, the sufficient cooling of glass fibers freshly drawn from a draw furnace is essential, asinadequately cooled glass fibers can lead to poor resin coating on the fiber surface and possibly fiber breakage during the process. In order to improve fiber cooling at a high drawing speed, it is common to use a helium injection into a glass fiber cooling unit in spite of the high cost of the helium supply. The present numerical analysis carried out three-dimensional thermo-fluid computations of the cooling gas flow and heat transfer on moving glass fiber to determine the cooling performance of glass fiber cooling depending on the method of helium injection. The results showed that afront injection of helium is most effective compared to a uniform or rear injection for reducing air entrainment into the unit and thus cooling the glass fibers at a high fiber drawing speed. However, above a certain amount of injected helium, there was no more increase of the cooling effect regardless of the helium injection method.

• Asian-Australasian Journal of Animal Sciences
• /
• v.5 no.2
• /
• pp.249-256
• /
• 1992

Italian ryegrass (Lolium multiflorum Lam.) was fractionated into leaf nutrient concentrate, fiber and deproteinised juice (DPJ). The fresh and fermented DPJs were concentrated and referred to as fresh deproteinised juice concentrate (FDPJC) and fermented deprotenised juice concentrate (FMTD DPJC). The FDPJC and FMTD DPJC were separately mixed with dried fiber and ensiled. Wilted crop silage and fresh fiber silage were also prepared from the same material crop. The nutritive value of these four silages were compared using four goats by $4{\times}4$ Latin square design. Green crop fractionation resulted lesser amount of crude protein and ash, and higher amount of neurtal detergent fiber, acid detergent fiber, cellulose and hemicellulose in fresh fiber. The pH of fresh fiber silage was lower than that of the other silages. Addition of FDPJC or FMTD DPJC to the dried fiber at ensiling did not improve the silage qualities; but all the silages were satisfactorily preserved. Goats fed these silages showed similar ruminal pH and total volatile fatty acid concentrations. But addition of FMTD DPJC was effective on increasing ruminal acetic acid concentration reducing propionic acid concentration. Ruminal n- and iso- butyric acid concentrations were proportional to that of propionic acid. High ammonia content of the silage containing FMTD DPJC was reflected to the ruminal ammonia concentration, urinary nitrogen excretion and serum urea level of goats. Inclusion of FDPJC or FMTD DPJC added 15 to 25% dry matter to the fiber silages with a little reduction in the digestibilities of most components of the silages.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.1
• /
• pp.75-83
• /
• 2014

In order to prevent brittle failure of concrete, steel fiber reinforcement is effective composite material. However ductility of steel fiber reinforced concrete may be limited due to shrinkage caused by large content of cement binder. Chemical prestressing for steel fiber reinforcement in cement matrix can be induced through expansive admixture and this can increase reinforcing effect of steel fiber. In this study, mechanical performances in concrete with CSA (Calcium sulfoaluminate) expansive admixture and steel fiber reinforcement are evaluated. For this work, steel fiber reinforcement of 1 and 2% of volume ratio and CSA expansive admixture of 10% weight ratio of cement are added in concrete. Mechanical and fracture properties are evaluated in concrete with steel fiber reinforcement and CSA expansive admixture. CSA concrete with steel fiber reinforcement shows increase in tensile strength, initial cracking load, and ductility performance like enlarged fracture energy after cracking. With appropriate using expansive admixture and optimum ratio of steel fiber reinforcement, their interactive action can effectively improve brittle behavior in concrete.

• Composites Research
• /
• v.12 no.2
• /
• pp.10-25
• /
• 1999

A new evaluation method for the interfacial properties of fibrous composites based on a fragmentation technique is proposed by using the gradual multi-fiber composite, in which the inter-fiber spacing is gradually changed. The results showed that as the inter-fiber distance increased, the aspect ratio of broken fibers decreased while the interfacial shear strength between the fiber and matrix increased. When the reciprocal of the inter-fiber destance was taken for the above relations, both the aspect ratio and interfacial shear strength showed a saturated value. This means that the gradual multi-fiber composite indicates an upper bound in aspect ratio and an upper bound in interfacial shear strength. It was concluded that this fragmentation test could be a new method for composite evaluation, since reducing a difference between these two bounds is effective for composite strengthening. In addition an elastoplastic finite element analysis was carried out to relate the above results with fiber stress a distribution around fiber breaks. It was proved that the bound obtained in the gradual multi-fiber composite test is closely related to stress concentrations caused by a group of multi-fiber breaks.

• Journal of the Korea Concrete Institute
• /
• v.19 no.2
• /
• pp.145-151
• /
• 2007

The shear failure modes of FRP strengthened concrete beams are quite different to those of the beams strengthened with steel stirrups. When the beams are externally wrapped with FRP composites, many beams fail in shear due to concrete crushing before the FRP reaches its rupture strain. In order to predict the shear strength of such beams, the effective strain of the FRP must be blown. This paper presents the results of an experimental study on the performance of reinforced concrete beams externally wrapped with FRP composites and infernally reinforced with steel stirrups. The main parameters of the tests were FRP reinforcement ratio, the type of fiber material (carbon or glass) and configuration (continues sheets or strips). The experimentally observed effective strain of the FRP was compared with the strain calculated using a proposed method.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.38 no.3
• /
• pp.213-218
• /
• 1993

An experiment was carried out to investigate the effects of plant growth regulators on the growth and fiber yield of ramie. Gibberellin (GA) and Atonic acid were applied at the various levels of application dates, application frequencies and concentration. Stem growth of ramie increased greatly by applying GA on the meristem of shoot apex. Among three treatments of application frequencies of GA, that is, one time application at the stage of stem length with 50cm, twice applications at the stem length of 50cm and 100cm, and three times applications at stem length of 50cm, 100cm and 150cm, stem growth increased more as application frequency increased. GA application is more effective on stem growth at the later stage of growth than the earlier growth stage. GA treatment of 100 to 300 ppm is more effective on stem elongation than 50 ppm, which was due on the elongation of internodes without increase in number of nodes. One time application of GA enhanced leaf growth more or less regardless of concentration, but GA was applied more frequently, leaf growth was inhibited more at higher concentration. Fiber yield was the highest at the treatment of three times application of GA with 100 ppm. This treatment also showed the highest percentage of fiber with 5.3%, which is much higher value compared with that of control treatment with 4.6%. Atonic acid was less effective on stem elongation than GA, but it also seemed to be effective on the enhancement of fiber development.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.2
• /
• pp.117-124
• /
• 2015

Currently, Eco-friendly construction materials are widely utilized for reducing $CO_2$ emission in construction. Furthermore various engineering fibers are also added for improving a brittle behavior in concrete. In the paper, concrete specimens with 10% and 20% replacement ratio with RHA (Rice Husk Ash) are prepared, and engineering behaviors in RHA and OPC concrete are evaluated with different addition of coconut fiber from 0.125~0.375% of volume ratio. Several basic tests including compressive strength, tensile strength, flexural strength, impact resistance, and bond strength are performed, and crack width and deflections are also measured in flexural test. RHA is evaluated to be very effective in strength development and 0.125% of fiber addition leads significant improvement in tensile strength, ductility, and crack resistance. RHA and coconut fiber are effective construction material both for reutilization of limited resources and performance improvement in normal concrete.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.32 no.1
• /
• pp.10-18
• /
• 2000

To improve the physical properties of OCC (Old Corrugated Container) fibers, we used the mechanical pre-treatment on the fibers before refining . The mechanical action in the Hobart mixer induced high shear and compression on the fibers, which resulted in changes of fiber internal structure, and microcompressions on the surface of the fibers. We evaluated the amount of mechanical treatment on the fibers by fiber curl index for convenience. Four different refining techniques were applied to the pre-treated fibers (valley beater, Kady mill, PFI mill, and Impact refining) to find the best combination of the pre-treatment and the refining methods. Conclusions were summarized as followed. 1. Mechanical pre-treatment in Hobart mixer for more than 1 hour caused the increase of curl index of OCC fibers, and increased breaking length, burst index, and tear index the handsheets more than 10 % in this experiment. 2. Kady mill and PFI mill refining were effective in keeping fiber length from shortening Kady mill and Valley beater refining straightened out the fiber curls, and reduced the curl index. 3. Valley beating reduced fiber length very fast and generated fines more than other refining methods. 4. To increase breaking length and burst strength while keeping tear strength , combination of mechanical pre-treatment and Valley beating were most effective.

• Korean Journal of Community Nutrition
• /
• v.13 no.3
• /
• pp.426-438
• /
• 2008

The purpose of this study was to examine bowel habits, dietary habits, and nutrient intake of constipated adults, and the effects of prune products on relieving constipation symptoms. Fifty one adults with self-reported constipation (mean age 23 years, range 19-41 years, 10 males and 41 females) participated in this study. After a baseline survey on bowel habits and dietuy habits, participants were asked to consume at least 50 g of prune and 200 ml of prune juice per day during a 4-week period in addition to usual diet. Nutrient intake was estimated by a 24 hour recall at the baseline and once every week by diet records during the intervention. Data were analyzed after classifying the subjects into mild constipation group and severe constipation group by the severity of the symptoms. During the intervention, the subjects with mild constipation consumed 56 g of prunes (about 5.6 fruits) and 200 ml of prune juice, and the subjects with severe constipation consumed 59 g of prunes (about 5.9 fruits) and 207 ml of prune juice. Average intakes of energy, dietary fiber and water of the subjects in the mild constipation and severe constipation group increased during the intervention compared to the baseline. Average dietary fiber intake of the mild constipation and severe constipation groups significantly increased from 12.5 g and 11.6 g at the baseline to 18.5 g and 16.8 g after consuming prune products, respectively. These changes were accompanied by an increase in the number of bowel movements, a decrease of defecation time, a change to a softer stool consistency, and a decrease of abdominal pain during defecation. Seventy two subjects answered that prune products were effective to improve their overall constipation symptoms. Our data show that supplementation of prune products is effective to provide energy, dietary fiber and water, and to relieve constipation symptoms for constipated adults.

• Journal of Ocean Engineering and Technology
• /
• v.15 no.1
• /
• pp.98-103
• /
• 2001

This paper is conducted to compare the seismic design standard of a bridge column such as the Korean Bridge Design Standard(KBDS), EC 8, NZS 3101 and ATC 32. The KBDS adopted the seismic design requirements in 1992. The earthquake magnitude in Korea is compared with those in the west coast of the USA. It may be said that the current seismic design requirements of the KBDS provides design results, that are too conservative especially for transverse reinforcement details and amounts in reinforced concrete columns. This fact usually creates construction problems in concrete casting, due to congestion of transverse reinforcement. Furthermore, the effective stiffness; $I_{eff}$ depends on both the axial load P/$A_gF_{ck}$ and the longitudinal reinforcement ratio $A_{st}/A_g, so it is the conservative to use the effective stiffness I$_{eff}$ than the gross section stiffness Ig. Seismic design for the transverse reinforcement content of the concrete column was analyzed and considered to have an extreme-fiber compression strain, response modification factor, axial load and effective stiffness etc.c.