• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.90-95
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• 2004

Pitch pine (Pinus rigida) has been planted in Korean forests for several decades, primarily for erosion control and use as a fuel supply. To enhance its value, and especially potential use as lamina for structural glued laminated timber (glulam), log quality and lumber yield of pitch pine were evaluated in this study. Trees from pure pitch pine stands with an average diameter at breast height of 32 cm were felled and bucked into 3.6m long 15 cm minimum butt-end diameter logs. Over 80% of the logs were classified to No.2 or No.3 visual grade group. Upon sawing total lumber yield was 55.2%, 39.9% for structural glulam lamina, 7.2% for louver, and 8.1% for miscellaneous use. The final lumber yield for manufacturing structural glulam, after cross-cutting to eliminate knots and finger jointing, was only 15.3%. To enhance this manufacturing yield requires that the rate of knot-included lumber used as lamina be raised. However arrangement of the knot-included lamina, whose mechanical properties need to be accurately evaluated, must be optimized to minimize any reduction to the structural glulam strength. The log quality and lumber yield of pitch pine evaluated in this study are expected to facilitate proper planning for wood product manufacture in the Korean lumbering and glulam industrial field, which has not previously dealt with this species.

• Journal of Practical Agriculture & Fisheries Research
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• v.6 no.1
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• pp.63-72
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• 2004

This study was conducted to determine the growth and properties of green soybean sprouts(Vigna umbellata Thunb.) in soil culture. Patkong which is a small grain variety was sawn on electric heated hot bed in the greenhouse. Temperature of the culture bed were respectively 17, 20, 25, and 30℃ and water temperature were respectively 14, 17, 20 and 25℃. The kinds of soil used for this study were upland soil, sand, peatmoss and Pearlite, loess, loess and activated carbon. BA was treated in the concentrations of 240 times, 80 times, 40 times besides control. High temperature of 25 and 30℃ increased sprout yield compared to lower temperature but caused to decay from 7 days after sawing. Thus, the most optimum temperature for soil culture was 20℃. The best soil was sand of which increased fresh weight of 850g during same period. Addition of BA was most effective to promote sprout growth in the concentration of 80 times. Compared to general soybean sprouts, green soybean sprouts were 50% higher in fiber but 72% lower in glucide. Vitamin B was 200% higher in green soybean sprouts but vitamin C was higher in general soybean sprouts.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.87-96
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• 2005

This study was carried out to evaluate the shear bond strength and adhesive bond durability of structural glued laminated timber (glulam) manufactured with mixed species lumber of Korean red pine, Korean pine and Japanese larch, using resorcinol adhesive and water-based polymeric-isocyanate adhesive (WPI). Each board used as a glulam lamina was graded by visual inspection. The visual lumber grade of the all species was very low due to the large size and number of knots and the steep slope of grain. In view of the results, appropriate pruning, sawing and drying processes might be needed to produce high grade lamina lumber with small knot size and drying defect free. Shear bond strength of every tested glulam specimen ranged between 7.9 and $9.9N/mm^2$, and much higher than the Korean Standard (KS) for glulam shear bond strength, $7.1N/mm^2$. There was not much shear bond strength difference between wood/resorcinol and wood/WPI. The resorcinol adhesive bond durability exceeded KS requirements. However, delamination on the end-grain surfaces of WPI glulam submerged in both room temperature and boiling water severely occurred, and its durability did not meet KS requirements. Further investigations may be required, and special care should be taken, to ensure long service life of WPI glulam used for exterior application. Results of this study are expected to be useful for improvement of mechanical properties and structural performance of mixed species glulam.