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최돈하,윤승락,이동흡,손승현 한국목재공학회 1992 목재공학 Vol.20 No.4
Seven white rot fungi (Irpex lactenis, Coriolus hirsutus, Lopharia mirabilis, Schizopora paradoxa, Ganoderma lucidum, Pleurotus ostreatus and Pycnaporus coccineus) native to Korea anti two famous exotic lignin-degradable white rot fungi (Coriolus versicolor and Phanerochaete chrysosporium)were investigated to clarify their physiological and physicochemical characteristics on white-rotted wood blocks. G. lucidum degraded wood blocks more seriously than those by exotic lignin-degrading fungi, C. versicolor and P. chrysosporium, but only slightly decreased the strength of wood which was compared to the weight loss, persumably on the account of its small use of cellulose when attacking wood. It is quite interesting to note that the holocellulose degradation rate of G. lucidum was also higher than any of the other tested fungi. The order of fungi, according to the lignin-decomposing rates, was G. lucidum$gt;P. coccineus$gt;C. versicolor$gt;S. paradoxa$gt;P. chrysosporium$gt;L. mirabilis$gt;P. ostreatus$gt;C. hirsutus$gt;I. lactenis. The lignin degradation of G. lucidum and P. coccineus which were collected in Korea was greater than that of C. versicolor and P. chrysosporium. If holocellulose degradation is not considered, G. lucidum has the merit of actual application in biomass conversion due to lignin remotral.
수피에 의한 중금속 흡착시 경금속의 영향과 중금속간의 흡착 경쟁
김동호,최돈하,백기현 한국환경농학회 1997 한국환경농학회지 Vol.16 No.2
When the light metals such as Ca^(++) and Mg^(++) were added to heavy metal solution, the adsorption of heavy metals was increased by 20 to 30% more, but there were no differences between species. Pb^(++) was the most adsorbed metal(99.5%), and the adsorption ratio of Cd^(++) was significantly improved. In addition, when the light metal concentration was increased to 100ppm, the adsoption ratios of all four heavy metals were reached to 92 to 99%, while coniferous barks showed only 85 to 92%. On the mixture of four heavy metals, the adsorbed amount of each metal was significantly reduced, compared with that of one heavy metal, while Zn^(++) showed the adsorption improvement to 95%. On the column experiment, Pb^(++) was almost completely adsorbed in the upper part of column, and the adsorbed amount of Cu^(++) was gradually decreased depending on column depth. However, Cd^(++) and Zn^(++) were not influenced by column height, and constantly adsorbed on various column height. Based on the above results, each heavy metal had different adsorption mechanism.
포화세멘트 수용액에 의한 추출단당류가 목질세멘트 복합체의 경화에 미치는 영향
신동소,안원영,최돈하 한국목재공학회 1984 목재공학 Vol.12 No.3
This experiment was carried out to investigate the effects of monosaccharides extracted by saturated portland cement solution on the cement setting in comparision with the inhibitory index (Ⅰ)of each lignocellulosiccement system. The woad species which have been widely reforested in Korea, Populus alba-grandulosa, Larix leptolepis, Abies holophylla, Pinus koraiensis, Pinus rigida, Pinus densiflora and agricultural wastes of rice husk and.,rice stalk were used at this study. The wood meal, 0.50g on dry weight basis, through 0.8.3 mm(20 mesh} and retained on 0.35mm (40 mesh) screen was extracted by 25 ml saturated Portland cement solution and the pH of saturated Portland cement solution was 12.7. To eliminate cation exsisting in the extracted solution, the canon exchange column was used (Fig. 4). Afterwards the extracted monosaccharides were reducers into alditols with sodium borohydride and analyzed by the gas-liquid chromotography for xylan, mannan, arabinan, galactan, glucan. The heat of cement hydration for lignocellulosic-cement system was measured in Dewar flask (Fig. 2), And then the inhibitory indices were calculated from maximum hydration temperature, time and maximum slops of hydration curve of ligno cellulosic-cement systems. The results obtained were as follows; (l) The inhibitory index of pines-Pinus rigida (Ⅰ=29.33) and Pinus densiflora (Ⅰ=35.76), were lower than that of poplar-Populus alba-glandulosa (Ⅰ=41.48), and the Index of Larix leptolepis (Ⅰ=73.00) was the highest among eight lignocellulosic-cement systems, and accordingly both Pinus rigida and Pinus desiflora were seemed to be good wood species for wood-cement composite manufacture. (2) In case of Pinus rigida, the inhibitory index was 29.33 and the ratio of the hexoses to the pentoses was 6.04 and in case of Larix leptolepis, the index and the ratio were 73.00 and 35.19, respectively. Therefore the inhibitory index increased with increasing the ratios of the hexoses to the pentoses. (3) The richer amount of xylose and mannose in species caused decreasing the slops of the hydration curve of the lignocellulosic-cement system, probably due to the chemical adsorption of the acetyl groups in the hemicellulose on the surface of cement grains. (4) The amoun of xylose and mannose were significant to the inhibitory index of each lignocellulosic-cement system but any specific relation between the amount of glucose and inhibitory index was not found.
목질의 열수추출 및 CaCl2 첨가가 목질 - 세멘트 보드의 휨강도 및 팽윤율(膨潤率)에 미치는 영향
안원영,신동소,최돈하 한국목재공학회 1985 목재공학 Vol.13 No.3
The effects of pre-treatments, the hot water extraction of wood meal and the addition of chemical (CaCl₂) to wood-cement water system on the properties of wood-cement composite such as modulus of rupture (MOR), modulus of elasticity (MOE), water sorption ratio and swelling ratio of resulting boards were studied in this experiment. The wood meals through 0.83㎜(20 mesh) and retained on 0.42㎜(35 mesh) screen were prepared from Pines densiflora S. et Z.and Larix leptolepsis G. For hot water extraction, 500 grams of wood meal for each species were heated to boiling with 1,500㎖ of distilled water in 2-liter beaker for 6 hours. Every 2 hours, the wood meals were washed with boiling distilled water and repeated to boiling again. After 6 hours boiling, the boiled wood particles were collected by pouring this particles on 200 mesh screen. The collected particles then washed twice with hot distilled water and dried for 24 hours ire an oven at 109 ± 2℃. A mixture of 663.4 grams of cement with 331.7 grams of wood meal based on oven-dry weight were dry-mixed in a plastic vessel. The mixture was kneaded with 497.6㎖ of distilled water in the ratio of 1.5ml of water to a gram of wood meal. To add calcium chloride to the mixture as an accelerator, CaCl₂, 4% solution by weight per volume, was added to pine-or larch-cement board in the ratio of 3% to cement weight. To set wood-cement board, this mixture was clamped at 30㎝ × 30㎝, in thickness of 1.5㎝ for 3 days at room temperature, declamped and then placed at open condition for 17 days. The target density was 1.0. The four specimens sized to 5㎝ in width and 28㎝ in Length were used for MOR and MOE test for each treatment. After MOR test, the tested specimens were cut to the size of 5㎝ × 5㎝ for water sorption and swelling test. The twenty specimens used to measure the water sorption ratio {soaking 24 hours) and ten of these were used for swelling ratio measurement. The results obtained were as follows: 1) Larch was not suitable for wood-cement boards because larch-cement board developed no strength, but pine showed 97.9㎏/㎠ by hot water extraction. 2) To increase MOR, hot water extraction was more effective than the addition of CaCl₂ in pine and larch because the CaCl₂ addition was seemed to speed up the ratio of cement hydration without reacting with the wood substances. 3) The -water sorpdiun ratio was lowered by the addition of CaCl₂ to wood-cement system because the chemical additive accelerated the rate of cement hydration. 4) In pine-cement board, the swelling ratio from 0.37 to 0.42 percent was observed in length and the swelling ratio from 0.88 to 2.0 percent in thickness. As a rule, the swelling ratio of wood-cement board was very tow and the swelling ratio in thickness was higher than in length.