Time filter

Source Type

Park J.-S.,Korea forest Research Institute | Hwang K.-H.,Korea Forestry Promotion Institute | Jeong G.-Y.,Chonnam National University
World Conference on Timber Engineering 2012, WCTE 2012 | Year: 2012

Stiffness of timber floor has been considered as one of major factors that influence the insulation performance against impact sound. Researches on evaluating the effect of floor constitutions have been carried out through the field measurements for timber framed buildings in Korea. It is concluded that the impact sound pressure level at the relatively lower frequency of 63Hz governs the overall insulation performance and can be improved by the reinforcement of floor stiffness, in case of heavy impact sound. From the result of this study, the effect of stiffness reinforcement on the insulation performance against heavy impact sound is shown very significant when the span of joist is shortened by the addition of beam at the mid-position of original span. Source

Kim J.-Y.,Seoul National University | Kim T.-S.,Seoul National University | Eom I.-Y.,Seoul National University | Eom I.-Y.,Korea Research Institute of Chemical Technology | And 4 more authors.
Journal of Hazardous Materials | Year: 2012

In this study, chromated copper arsenate-treated wood (CCA-W) and alkaline copper quaternary compounds-treated wood (ACQ-W) were subjected to fast pyrolysis at 500°C for ca. 2. s to produce bio-oil and char. The physicochemical properties of the pyrolytic products as well as the distribution of heavy metals - arsenic, copper and chrome - during fast pyrolysis were investigated. The water content, viscosity, pH and higher heating value (HHV) of bio-oil from CCA-W were 24.8. wt%, 13.5. cSt, 2.1 and 16. MJ/kg, respectively, whereas those of bio-oil from ACQ-W were 27.9. wt%, 16. cSt, 3.0 and 14.1. MJ/kg, respectively. The yields of bio-oil from CCA-W and ACQ-W were 43.3% and 46.6%, respectively, significantly lower than that of control (61.6%). In the pyrolytic products of CCA-W, the concentrations of arsenic, copper and chromium were determined to be 36.4. wt%, 74.0. wt% and 75.4. wt% in char, respectively, 34.5. wt%, 10.3. wt% and 9.0. wt% in bio-oil, respectively, and 29.0. wt%, 15.7. wt% and 15.5. wt% in gas, respectively. In addition, most of the copper appeared in the char (98.8. wt%) and only a trace amount of copper was detected in the bio-oil (0.2. wt%) produced by ACQ-W. © 2012 Elsevier B.V. Source

Jeong G.Y.,Chonnam National University | Park J.S.,Korea forest Research Institute | Hwang K.H.,Korea Forestry Promotion Institute
Wood and Fiber Science | Year: 2012

The goal of this study was to evaluate the load-carrying capacity of dovetail connections. Different tenon angles (y), tenon neck widths (w1), tenon head widths (w2), and tenon heights (h) were used to analyze stress distribution and strength from dovetail connections using the finite element method (FEM). Although different stress distributions were found from the FEM models, shear and tension perpendicular to the grain stresses were found to be the most critical stresses controlling strength of the dovetail connection. Strength of the dovetail connection predicted from the deterministic FEM models was validated from the results of experimental tests. A combination of four geometric parameters for mortise and tenon from the dovetail connection maximizing load-carrying capacity was found. Allowable load-carrying capacity of the dovetail connection was estimated using the stochastic finite element method associated with allowable stress design and load resistance factor design concepts. © 2012 by the Society of Wood Science and Technology. Source

Kim C.,Gyeongnam National University of Science and Technology | Park J.-H.,Gyeongnam National University of Science and Technology | Byun J.-K.,Korea Forestry Promotion Institute | Ma H.-S.,Gyeongsang National University
Annals of Forest Research | Year: 2013

This study was conducted to evaluate the litter fall and nutrient status of green leaves and leaf litter at various compound ratios of fertilizer in 28-year-old sawtooth oak (Quercus acutissima Carruth.) stands. The compound ratios of the fertilizer were N3P4K1 (100 kg N ha-1, 133 kg P ha-1, and 33 kg K ha-1), N6P4K1, N2P2K1, N3P8K1, N3P4K2, and N0P0K0 (control). Varying ratios of NPK were applied for three years (2002 - 2004), and the litter fall and green leaves were collected for one year (May 2005 - May 2006) and at the end of growing season (September 2005). Leaf litter was significantly higher (P < 0.05) in the N3P4K2 (3,423 kg ha-1 year-1) than in the N3P8K1 (2,741 kg ha-1 year-1) and N2P2K1 (2,891 kg ha-1 year-1) treatments. The N concentrations of the green leaves were significantly higher in the compound ratios of fertilizer (N3P4K1, N6P4K1, N3P8K1) than in the N0P0K0 treatment, but the N concentrations of the leaf litter were not affected by the fertilizer. The P and K concentrations in the green leaves were significantly higher in the highest dose (N3P8K1 and N3P4K2) of these nutrients than in the N0P0K0 treatment. The nutrient inputs by the leaf litter corresponded to the differences in the leaf litter mass or nutrient concentrations rather than the various compound ratios of fertilizer. Nutrient use and resorption efficiencies were only weakly controlled by various compound ratios of fertilizer. The results indicate that the nutrient status of green leaves may serve as an indicator of various compound ratios of fertilizer, whereas litter fall, nutrient use and resorption efficiency can be attributed to inherent soil conditions or stand characteristics following fertilizer application in sawtooth oak stands. Source

Kim Y.S.,Korea forest Research Institute | Byun J.K.,Korea Forestry Promotion Institute | Kim C.,Gyeongnam National University of Science and Technology | Park B.B.,Korea forest Research Institute | And 2 more authors.
Landscape and Ecological Engineering | Year: 2014

This study was conducted to determine fertilizer compound ratios suitable for soil conditions and tree seedling growth in recently burned areas in Korean forests. Currently, the conventional fertilizer ratio applied to undisturbed forests in Korea is N:P:K 3:4:1. In this study, Japanese red pine (Pinus densiflora S. et Z.) seedlings planted in the burned area were fertilized over four growing seasons with the following NPK compound ratios: unfertilized (CON), 3:4:1, 6:4:1, 3:8:1, and 3:4:2. Fertilization generally increased current-year needle nutrient concentrations of the seedlings, and the chlorophyll a:b ratio in CON was significantly lower than in all fertilized plots. Fertilization significantly affected the growth of the pine seedlings, which had 71-87 % more height growth and 29-67 % increased root collar diameter (RCD) compared to CON. The increases in height and RCD were significantly higher with the 6:4:1 and 3:8:1 ratios than with the 3:4:1 ratio. The 3:4:2 and 3:4:1 fertilizer ratios had no effect on the RCD growth of seedlings. This suggests that the early growth of pine seedlings could be improved by providing high N and P supplies to areas affected by forest fires rather than the conventional fertilizer ratio of 3:4:1 in Korean forest soils. Therefore, application of the suitable fertilization ratio may be a very effective way to reduce reforestation cost as well as to shorten restoration period. © 2012 International Consortium of Landscape and Ecological Engineering and Springer Japan. Source

Discover hidden collaborations