• Journal of the Korean Wood Science and Technology
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• v.12 no.2
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• pp.35-43
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• 1984

This study was carried out to investigate the block shear strength of the 2ply laminated wood composed of Pinus thunbergii with ureaformaldehyde resin as adhesives according to pressure (6, 9, 12, 15kg/$cm^2$), pressing time(5, 10, 20, 30 hrs.), amount of spread(54, 108, 217, 324g/$cm^2$), hardener(10, 20, 30, 40% of 10% $NH_4CL$ on resin) and extender(0, 5, 10, 15% wheat flour on resin), and the bending strength and bending young's modulus of laminated beam according to the number of ply. The results were summarized as follows; 1. According to pressing pressure with amount of spread 217g/$cm^2$ both dry and wet shear strength of laminated wood showed the highest in 15kg/$cm^2$, and hot-cold soaking treatment showed the highest in 9kg/$cm^2$, while all shear strength of dry, wet and hot-cold soaked laminated wood have been reduced with the increasing of pressing time. 2. According to amount of spread, adhesion strength with the dry, wet and hot-cold soaking treatments revealed the highest in 217g/$cm^2$ and have been reduced under or over 217g/$cm^2$ of spread. 3. According to addition of hardener and extender, all shear strength of laminated block with the dry, wet and hot-cold soaking treatments have been reduced in increasing of addition amount of hardener and extender. The bending strength of beam according to the number of ply showed the highest in 2ply laminated wood and horizontal loading beam to glue line had the higher in strength than the vertical loading.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.317-320
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• 2008

The Hot Stamping process, which is the hot pressing of steel parts using cold dies. can utilize both case of shaping and high strength due to the hardening effect of rapid quenching during the pressing. We carried out experiments of quenching rate and tempering treatments at temperatures of $200^{\circ}C$ and $300^{\circ}C$ and different soaking times. Tn this study, the mechanical properties and microstructure of micro boron alloyed steels after heat treatments are compared.

• Journal of the Korean Wood Science and Technology
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• v.14 no.4
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• pp.21-28
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• 1986

Plywood used for construction as a decorative inner material is inflammable and can fire accident, causing destruction of human life and property. In this study, 3.5mm Kapur plywoods were soaked in the 23% monoammonium phosphate solutions by cold soaking method 3, 6, 9hrs and hot-cold bath method for 3/3hrs, and redrying was carried out by press-drying at the platen temperature of 110, 130, 160, 180$^{\circ}C$, and then fire test was carried out to investigate burning point, flame exhausted length, frame spread length, back side carbonized area and weight loss. The results are as follows; 1. In cold soaking method for 3, 6, 9hrs. retentions of monoammonium phosphate were 0.377, 0.448, 0.498kg/(30cm)$^3$ respectively, and in hot-cold bath method for 3/3hrs, the retention was 1.331kg(30cm)$^3$ that exceeded the minimum retention 1.124kg/(30cm)$^3$. 2. Correlation coefficients among the variable were shown in table 2. From the table, it could be recognized that there were close negative correlations between the treatment and burning point, flame spread length, back side carbonized area, flame exhausted time and weight loss, and there was negative correlation between treating time and back side carbonized area, but there was positive correlation between platen temperature and burning point. 3. From table 3, it can be observed that there were highly significant differences for burning point, flame spread length, flame exhausted time, back side carhonized area, weight loss between treatments. And in 2-way interactions, there were also highly significant for burning point, flame spread length, flame exhausted time, weight loss between time x treatment. 4. It was observed that burning point, flame exhausted time, flame spread length, back side carbonized area, and weight loss in fire-retardant treated plywood were the best effects in fire-retardant treated plywood, water treated plywood and nontreated plywood. In conclusion, I can estimate that absorbed chemical contents by hot-cold bath method for 3/3hrs, have a lot of effects on fire-retardant factors such as burning point, flame spread length, flame exhausted time, backside carbonized area and weight loss, but platen temperatures have a little effects on the fire factors.

• Journal of Korean Society of Forest Science
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• v.56 no.1
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• pp.1-25
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• 1982

Plywood used for construction as a decorative inner material is inflammable and can cause fire accidents. causing destruction of human life and property. To diminish the fire disaster, fire retardant plywood is indeed required. In the methods of manufacturing the fire retardant plywood, a soaking method is occasionally used. However after soaking plywood into fire retardant chemical solutions redrying of soaked plywood is of the utmost importance. In this study 3.5mm and 5.0mm thickness plywoods were selected for fire retardant treatment. Treating solutions were prepared for 20% dilute solutions of ammonium sulfate, monoammonium phosphate, diammonium phosphate, borax-boric acid minalith, and water solution, 1-, 3-, 6-, and 9 hour-soaking treatments in borax-boric acid and minalith, and 6- and 9 hours in the other chemicals were applied and after the treatment hot drying was applied to treated plywoods at $90^{\circ}C$, $120^{\circ}C$ and $150^{\circ}C$ of press temperature. Drying rates, drying curves, water absorption rates of fire retardant chemicals, weight per volume and fire retardant degree of plywood were investigated. The results may be summarized as follows: 1) In the 9 hours-soaking treatment of fire retardants by hot and cold bath method, the chemical retentions of 3.5mm thickness plywood could be attained within the range ($1.125-2.25kg/(30cm)^3$) of minimum retention specification as follows: $1.353kg/(30cm)^3$ in monoammonium phosphate, $1.331kg/(30cm)^3$ in diammonium phosphate, $1.263kg/(30cm)^3$ in ammonium sulfate, $1.226kg/(30cm)^3$ in borax-boric acid. But the chemical retention, $0.906kg/(30cm)^3$, in minalith could not be attained within the range of minimum retention specification. And also in case of 5.0mm thickness plywood, chemical retentions, as $1.356kg/(30cm)^3$ and $1.166kg/(30cm)^3$ respectively, of ammonium sulfate and diammonium phosphate could be attained within the range minimum retention specification, but the other fire retardant chemicals could not. 2) In the 6- and - hours-soaking treatments of 3.5mm and 5.0mm thickness plywood, the drying curve sloped of chemical treated plywood was smaller than that of water treated. The drying rate related to thickness of treated plywood, was about three times as fast in 3.5mm thickness plywood compared with 5.0mm thickness plywood. 3) In the treatment at $120^{\circ}C$ of hot platen temperature, the drying rates of chemical-treated plywood showed the highest quantity in diammonium phosphate of 3.5mm and 5.0mm thickness plywood. But the drying rate of water treated plywood was highest during the 6- and 9 hours-soaking treatments. 4) The drying rate remarkably increased with proportion to increase of the platen temperature, and the values were respectively 1.23%/min., 6.54%/min., 25.75%/min. in hot platen temperature of $90^{\circ}C$, $120^{\circ}C$, $150^{\circ}C$ in 3.5mm thickness plywood and 0.55%.min., 2.49%/min., 8.19%/min. in hot platen temperature of $90^{\circ}C$, $120^{\circ}C$, $150^{\circ}C$ in 5.0mm thickness plywood. 5) In the fire retardant degree of chemical treated plywood, the loss in weight was the smallest in diammonium phosphate, next was in monoammonium phosphate and ammonium sulfate, and the greatest was in borax-boric acid and minalith. And the fire-retardant effect in burning time, flame-exhausted time and carbonized area were greatest in diammouniun phosphate, next were in monoammonium phosphate and ammonium sulfate, and the weakest were in borax-boric acid and minalith.