• Clean Technology
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• v.20 no.3
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• pp.232-240
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• 2014

The significance of thermoplastic polyolefin polypropylene (PP) lies in its potential to replace polyvinyl chloride (PVC), the most widely used material for automobile interiors (door trim, dash board), which discharges harmful compounds in certain conditions. Another benefit of PP (0.855 amorphous - 0.946 crystalline $g/cm^3$) is its low density compared to that of PVC ($1.1-1.45g/cm^3$), which reduces vehicle weight. Market demand for eco-friendly water-based adhesive/coating material is rising significantly as a substitute for solvent-based adhesive/coating material which emits VOC and causes harmful working conditions. Under such context, in this study, a series of eco-friendly waterborne polyurethane-urea primer (a paint product that allows finishing paint to adhere much better than if it were used alone) for hydrophobic PP were prepared from different mix of DMPA content, NCO/OH molar ratio, various wt% of silicone diol and various soft segment content, among which DMPA of 21 mole %, NCO/OH molar ratio of 1.2, modified silicone diol of 5 wt% and soft segment content of 73 wt% led to good adhesion strength. Additionally, the incorporation of optimum content of additives (0.5 wt% dispersing agent, 0.5 wt% levelling agent, 1.5 wt% antifoaming agent, 3.0 wt% matting agent) into the optimum waterborne polyurethane-urea also enabled good stability, levelling, antifoaming and non-glossy.

• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.129-136
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• 2000

The aucha perch, Coreoperca kawamebari was collected in Tam-jin river from February to June 1998. It was reared in the laboratory and observed the spawning behavior and early life history. Spawning season was from mid of April to the end of May in the Tam-jin river. The fertilized eggs were demersal of adhesive, transparent and spherical in shape. Egg diameter was 2.21~2.65 mm with several oil globule of 0.058~0.343 mm. Hatching occurred about 194 hours 23 minutes after fertilization at water temperature of $18{\sim}22^{\circ}C$. Newly-hatched larvae were 5.09~5.68 mm in total length(TL, mean: 5.38mm) with 10~11+18=28~29 myotomes and opened mouth and anus. Melanophores were distributed on the eye lens, on the head, around the yolk, on the dorsal part and the abdominal region of the trunk. After hatching 5 days larvae attained 6.12~6.68 mm in TL (mean: 6.47 mm), and the yolk sac was completely absorbed and transformed to postlarva stage. The larvae reached to the juvenile stage with all the fins were formed with complete set of fin rays (D. XII-12~13; A. III-8~10; P. 11~13; V. I-4~5) at the 22 days after hatching and of the larvae was 11.54 mm in total length. In 32 days after hatching, the juvenile was 13.05 mm in TL. This period was similar to adult in body form and the spot.