• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.45 no.4
• /
• pp.65-74
• /
• 2013

In the manufacture of corrugated box, the fibrous raw materials are mainly consisted of recycled papers, such as KOCC(Korean Old Corrugated Container), kraft sack, and AOCC(American Old Corrugated Container). Among these recycled waste paper, the proportion of KOCC is relatively higher than others in fibrous raw materials. Generally, KOCC shows some poor fiber properties and contains hazardous heavy metal sources. Therefore, it is to evaluate the property of recycled paper sources for eco-friendly corrugated box manufacture. In this study, the physical and mechanical properties of 3 kinds of recycled fibers and their mixed stocks were analyzed. The environmental assessment was also evaluated by analyzing the 4 representative heavy metal contents and evaporation residues in waste papers. As the results, KOCC showed the poorest fiber qualities and had the highest heavy metal contents and evaporation residues among the recycled fibers. Finally, the mechanical strength properties were increased by decreasing KOCC proportion of mixed stock conditions. In addition, the heavy metal contents and evaporation residues were also decreased by increasing recycled AOCC and kraft sack proportion.

• Applied Microscopy
• /
• v.15 no.1
• /
• pp.71-85
• /
• 1985

The ultrastructure on the dorsal vessel of 5-day-old cabbage butterfly, Pieris rapae L., was carried out using the transmission and scanning electron microscope. The results are as follows. 1) The aorta. The aorta is simple tubular type and consists of the inner and outer membrane of the myocardium and thick myocardium is located between them. However the inner membrane with $0.26{\mu}m$ thickness and outer membrane with $0.08{\mu}m$ are composed of fibrous materials, the former is composed of low and high densed fibrous materials and the latter appears homogeneous layer. The myocardium consists of typical striated muscles. The sarcomere with $1.6{\mu}m$ length and in cross section, each thick filaments are surrounded by $7{\sim}8$ thin filaments. The intercalated disc is joining the end of the two muscle cells, desmosomes and septate junctions are appeared between the neighboring muscle cells. 2) The heart. The heart composing of myocardium enclosed by its inner and outer membrane as the aorta has a series of well formed segmental chamber. The arrangement of myofilaments, cell adhensions and membrane elements are observed as same as at the aorta. The inner membrane of the heart is deeply invaginated into the myocardium than the outer membrane and a lot of well developed mitochondria with rod shape are aggregated in the folds. The longitudinally and transversely oriented tubule system formed by invagnation of the sarcolemma into the muscle bundle is built up dyad with the sarcoplasmic reticulum as the aorta. The slit is formed by deeply invagination of the inner membrane of myocadium toward the muscle layer and then the inner and outer membrane of myocardium are fused. Therefore, the ostium is formed between the myocardium and situated at the lateral side of the myocardium.

• Polymer(Korea)
• /
• v.31 no.3
• /
• pp.228-232
• /
• 2007

This purpose of this study is to enhance the hydrolysis of poly (butylene succinate-co-L-lactate) (PBSL) and poly [(R) -3-hydroxybutylate] (PHB), to develop materials with advanced medical absorbability and environmental suitability. The first method involves increasing the bioabsorbability of poly (glycolic acid) (PGA) in the core of the fibrous complex, while the second method involves making a complex fiber containing PBSL and PHB in the outer layer for improving environmental degradability Improvement in the hydrolysis of PBSL and PHB due to glycolic acid occurs by hydrolytic behavior of PGA. The drawing supporting the resulting PBSL/PGA fiber was executed at $65^{\circ}C$, where the orientation is well arranged in crystal form. Obtaining a PHB/PGA complex fiber in the proper crystal orientation at $50^{\circ}C$ was not possible since the arranged crystal orientation was only identified in drawings from temperatures above $50^{\circ}C$. Also, it is necessary to execute a smooth surface to achieve an on-line drawing since unevenness occurs in the fibrous surface from an in-line drawing.

• Archives of Metallurgy and Materials
• /
• v.63 no.3
• /
• pp.1433-1437
• /
• 2018

Neodymium-Iron-Boron (Nd-Fe-B) magnets are considered to have the highest energy density, and their applications include electric motors, generators, hard disc drives, and MRI. It is well known that a fiber structure with a high aspect ratio and the large specific surface area has the potential to overcome the limitations, such as inhomogeneous structures and the difficulty in alignment of easy axis, associated with such magnets obtained by conventional methods. In this work, a suitable heat-treatment procedure based on single-step and multistep treatments to synthesize sound electrospun Nd-Fe-B-O nanofibers of Φ572 nm was investigated. The single-step heat-treated (directly heat-treated at 800℃ for 2 h in air) samples disintegrated along with the residual organic compounds, whereas the multistep heat-treated (sequential three-step heat-treated including three steps;: dehydration (250℃ for 30 min in an inert atmosphere), debinding (650℃ for 30 min in air), and calcination (800℃ for 1 h in air)) fibers maintained sound fibrous morphology without any organic impurities. They could maintain such fibrous morphologies during the dehydration and debinding steps because of the relatively low internal pressures of water vapor and polymer, respectively. In addition, the NdFeO3 alloying phase was dominant in the multistep heat-treated fibers due to the removal of barriers to mass transfer in the interparticles.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.36 no.5
• /
• pp.353-359
• /
• 2010

Introduction: This study examined the effect of cyclosporine A (CsA) on the allogenic cranial bone graft in the mice. Materials and Methods: Twenty eight 12-week-old male ICR mice weighing 40 g were used. The experimental group was injected subcutaneously with CsA (10 mg/kg/day) diluted in Caster oil for 7 days prior to the graft until sacrifice. The control group was injected with the same solution without CsA. Two full-thickness bone defects with a diameter of 3 mm were made with a trephine bur in the parietal bone lateral to the sagittal suture. A calvarial defect of a mouse was grafted with allogenic calvarial bone disc from another mouse. The experimental and control groups were injected with CsA and the solution without CsA in the same manner before surgery, respectively. The mice were sacrificed at 1 week, 2 weeks and 4 weeks after the bone graft, respectively. Results: In the experimental group, fibrous connective tissues and small amounts of inflammatory cells were observed. At 2 weeks after the allograft in the experimental group, new bone formation in fibrous collagenous tissue and around the allogenic bone was noted. At 4 weeks after the allograft, new bone formation was active along and at the periphery of the mature allogenic bone. The proliferation of blood vessels increased in bone marrow. In the control group, fibrous tissues and inflammatory cells were observed around the allogenic bone and existing bone at 1 week. At 2 weeks after the allograft, the proliferation of blood vessels accompanied by inflammatory cells were scattered in the fibrous connective tissues. New bone formation around the allogenic and existing bone could be observed. At 4 weeks after the allograft, inflammatory cells were severely infiltrated around the allogenic bone. Osteoclasts were scattered along the allogenic bone and induced bone resorption. Conclusion: These results suggest that the daily administration of CsA (10 mg/kg/day) induces efficient immunosuppression without serious complications, and this protocol might be useful for the experimental model of allogenic bone grafts.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.7 no.2
• /
• pp.209-222
• /
• 1997

Authors surveyed the ground water near the waste disposed from a fiberglass production factory to confirm the presence of glassfiber in the water and to determine the effect of sampling conditions and storage on the recovery of fibrous materials in the ground water. Sample was collected at every 4 hours for 48 hours consecutively. After finishing the 48 hours sample, water sampling was done from each tap after repeated turning on and off the water for 30 seconds at each time. Sample was collected in the two 1.5 liter polyethylene bottle after vigorously shaking the bottle with the same water several times with the flowing tap water. At each paired sample, one bottle was stored stand still at room temperature, and the other sample was filtered immediately after sampling. Water was filtered on the Mixed Cellulose Ester filter with negative pressure. Each sample was divided into upper and lower layer. The other bottle was stored at room temperature standstill for 7 days and filtered in the same fashion as the other pair of sample did. Each MCE filter was divided into 4 pieces and one piece was treated with acetone to make it transparent. Each prepared sample was observed by two researchers under the light and polarizing microscopy, scanning electron microscopy and energy dispersive X-ra microanalysis. Fibers were classified by the morphology and polarizing pattern under the polarizing microscope, and count was done. 1. There was a significant fluctuation in number of the fibers, but there was no specific demonstrable pattern. 2. Non-polarizing fibers frequently disappeared after 7 days's storage. But cluster of fibers were found at the wall of the same container by scratching technique. 3. Polarizing fibers were usually found in between the filter and the manicure pasted area. Possible explanations for this phenomenon will be that either these fibers are very light or have electronic polarity. Hence, these fibers are not able to be attached on the surface of slide glass. 4. Under the scanning electron microscopic examination, the fibers which are not refractive under the light microscopy were identified as glassfiber. Other fibers which is refractive under the polarizing microscopy were identified as magnesium silicate fibers. It is strongly suggested that development of standardized method of sample collection and measurement of fibrous material in the water is needed.

• Journal of the Korean Ceramic Society
• /
• v.45 no.8
• /
• pp.464-471
• /
• 2008

The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten salt. Ceramic fibers, especially fibrous commercial glass filters were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. During the infiltration, ions of $Li^+$ and $F^-$ in the molten salts were reacted with the glass fiber and caused to be weaken the fiber strength.

• Korean Journal of Materials Research
• /
• v.23 no.9
• /
• pp.495-500
• /
• 2013

Mo-based thin films are frequently used as back electrode materials because of their low resistivity and high crystallinity in CIGS chalcopyrite solar cells. Mo:Na/Mo bilayer thin films with $1{\mu}m$ thickness were deposited on soda lime glass by varying the thickness of each layer using dc-magnetron sputtering. The effects of the Mo:Na layer on morphology and electrical property in terms of resistivity were systematically investigated. The resistivity increased from $159{\mu}{\Omega}cm$ to $944{\mu}{\Omega}cm$; this seemed to be caused by increased surface defects and low crystallinity as the thickness of Mo:Na layer increased from 100 nm to 500 nm. The surface morphologies of the Mo thin films changed from a somewhat coarse fibrous structures to irregular and fine celled structures with increased surface cracks along the cell boundaries as the thickness of Mo:Na layer increased. Na contents varied drastically from 0.03 % to 0.52 % according to the variation of Mo:Na layer thickness. The change in Na content may be ascribed to changes in surface morphology and crystallinity of the thin films.

• The Korean Journal of Ceramics
• /
• v.3 no.4
• /
• pp.229-234
• /
• 1997

Silicon carbide-carbon fiber composites have been prepared by partially Infiltrating porous carbon fiber composites with liquid silicon at a reaction temperature of $1670^{\circ}C$. Reaction between molten silicon and the fiber preform yielded silicon carbide-carbon fiber composites composed of aggregates of loosely bonded SiC crystallites of about 10$\mu\textrm{m}$ in size and preserved the appearance of a fiber. In addition, the SiC/C fiber composites had carbon fibers coated with a dense layer consisted of SiC particles of sizes smaller than 1$\mu\textrm{m}$. The physical and mechanical properties of SiC/C fiber composites were discussed in terms of infiltrated pore volume fraction of carbon preform occupied by liquid silicon at the beginning of reaction. Lower bending strength of the SiC/C fiber composites which had a heterogeneous structure in nature, was attributed to the disruption of geometric configuration of the original carbon fiber preform and the formation of the fibrous aggregates of the loosely bonded coarse SiC particles produced by solution-precipitation mechanism.

• Korean Journal of Materials Research
• /
• v.17 no.9
• /
• pp.493-499
• /
• 2007

Oil-based nanofluids were prepared by dispersing nonconducting fibrous $Al_2O_3$ and spherical AlN nanoparticles in transformer oil. In this study, the effects of wet grinding and surface modification of particles on thermal and electrical properties of nanofluids were investigated. Grinding experiments were conducted with high-speed bead mill and ultrasonic homogenizer and nanoparticles were surface modified by oleic acid and polyoxyethylene alkyl acid ester(PAAE) in n-hexane or transformer oil, at the same time. It is obvious that the combination of nanoparticle, dispersant and dispersion solvent is very important for the dispersity of nanofluids. For nanofluids containing 1.0vol.% AlN particles in transformer oil, the enhancement of thermal conductivity was 11.6% compared with pure transformer oil. However, the electric-insulating property of AlN nanofluids was very low due to used dispersant itself. Therefore, the effect of the dispersant on thermal/electrical/physical properties of the transformer oil should be considered before selecting a proper dispersant.