• Journal of Adhesion and Interface
• /
• v.13 no.2
• /
• pp.58-63
• /
• 2012

CFRP chip is the byproduct from carbon fiber reinforced plastic (CFRP) processing. CFRP chip is not simply a waste mainly composed of fine carbon fiber and epoxy resin. CFRP chip keeps matrix to maximize their reinforcing effect. To obtain a uniform length of carbon fiber in CFRP chip, chip was chopped ina mortar. CFRP chip should be purified to get better interface adhesion. Epoxy resin on the carbon fiber was removed by $H_2O_2$ surface etching treatment. Optimal dispersion and fabrication conditions of CFRP chip embedded in phenolic resin were determined by thermal stability for fire retardant applications. CFRP chip-phenolic composite exhibits better mechanical and thermal properties than neat phenolic resin. Surface condition of CFRP chip-phenolic composite was evaluated by static contact angle measurement. Contact angle of CFRP chip-phenolic composite was greater than neat phenolic due to heterogeneous condition of fine carbon fibers. From the evaluation for fire retardant (ASTM D635-06) test, thermal stability of CFRP chip-phenolic composite was found to be improved with higher concentration of CFRP chip.

• The Journal of Korea Assosiation for Disability and Oral Health
• /
• v.15 no.1
• /
• pp.50-54
• /
• 2019

Muscular dystrophy (MD) is a heterogeneous group of inherited neuromuscular disorders, characterized by progressive muscle weakness. Severity of the disease ranges from mild to severe, and the disease is mostly caused by mutations in a number of genes. These genetic mutations cause lack of proteins which are essential for muscle cell stability. Muscle fibers are gradually replaced by fat and fibrous tissue. The muscles of the head and neck are affected in several types of MD that manifest as altered craniofacial morphology and dental malocclusion. A 3-year-10-month old, 15.0 kg boy with MD presented to Seoul National University Dental Hospital, Seoul, South Korea because of extensive carious teeth. A number of dental caries in primary dentition were identified during clinical oral examination. Due to dental anxiety and underlying systemic disease, general anesthesia was considered. General anesthesia was induced and maintained with intravenous anesthetics, propofol and remifentanil. Caries treatments - resin restoration, pulpectomy, zirconia crown restoration, stainless steel crown restoration - were performed. Under general anesthesia, successful dental procedure was done. Total intravenous anesthesia (TIVA) was performed instead of inhalation anesthesia in order to avoid risk of complications such as malignant hyperthermia and life-threatening rhabdomyolysis. With decreasing muscle function, plaque control becomes more difficult and leads to gingivitis. Especially, the open-mouth posture worsens gingivitis and can leads to malocclusions and problems in swallowing. Regular and periodic dental care is essential for maintaining oral health for patients with MD.

• Journal of Korean Society of Forest Science
• /
• v.45 no.1
• /
• pp.62-67
• /
• 1979

Ultraviolet microscopy of ultrathin sections of wood has proved to be one of the useful means for determining the lignin distribution in the various regions of the cell wall. Also, spectral approach and quantitative analysis of isolated compound middle lamella fraction from birch xylem have revealed that the lignin associated with the vessel secondary wall and middle lamella is composed predominantly of gualacylpropane units. Lignin deposited in the fiber and ray parenchyma secondary walls is composed mostly of syringylpropane units. The middle lamella lignin around fibers and ray cells contains both guaiacyl and syringyl propane quits. On the basis of the results above, this research was carried out to clarify the origin of milled wood lignin (MWL) by analysing the chemical characteristics of ML MWLs extracted at various milling stages. The amount of phenolic hydroxyl-, ${\alpha}$-carbonyl-, and methoxyl-group in the MWL's increases the milling time. And progressive mining contributes to the merease of ratio of syringylaldehyde to vanillin(S/V ratio) after nitrobenzene oxidation of MWL. Accordingly, It could be concluded that milled wood lignin extracted at the initial milling stage derives from compound middle lamella region of cell wall, whereas, with progressive milling, lignin of secondary wall of fiber is introduced gradually to milled wood lignin. These results are suggesting that heterogeneous chemical structure of lignins in hardwood exists. Although milled wood lignin at the initial stage seems to have lower molecular weight in comparison with milled wood lignin extracted at final milling stage from the result of Gel-filtration curves, further study would be required on molecular weight distribution of milled wood lignin in future.