• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.143-152
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• 2009

This study has been carried out to estimate carbon contents in an average 37-years-old Pinus densiflora plantations and an average 42-years-old natural Quercus acutissima stands in Gongju, Chungnam Province. Average carbon concentration in stemwood, stembark, branch, foliage, and root were 54.59% in Pinus densiflora and 53.73% in Quercus acutissima stands. Aboveground carbon contents was estimated by the equation model logWt = A + BlogD where Wt is oven-dry weight in kg and D is DBH in cm. Total carbon contents was 79.28t/ha in Pinus densiflora stands and 71.52t/ha in Quercus acutissima stands. Net primary carbon production was estimated at 9.79tC/ha/yr in Pinus densiflora stands and 5.52tC/ha/yr in Quercus acutissima stands.

• Journal of the Korean Wood Science and Technology
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• v.11 no.3
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• pp.14-22
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• 1983

The purpose of this study was to evaluate the effect of short-term paraquat treatment without insecticides on the enhancement in oleoresin of pitch pine (Pinus rigida M.) at various distances from the wound height. The trees were treated with 0.5, 2 and 4% paraquat solutions using the bore-hole technique. Duplicate cores from treated and untreated sides of treated trees were made at 5 height levels (-0.3, 0.0, 0.3, 0.9 and 1.5 m above the wound height) at 3 months after treatment. The alcohol-benzene extractives based on unextracted oven-dry cores were taken as oleoresin contents. The results were as follows: 1. The effect of oleoresin enhancement at wound height were not affected by paraquat concentration. 2. Ascending distance of the enhancing effects above the wound height was directly related to paraquat concentration. Only in 4% paraquat treated trees, the effect extended to 1.5 m above the wound height. 3. As a result of examining descending distance of the enhancing effects at 0.3 m below the wound height, the effects extended to there in 4% and 2% paraquat treated trees.

• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.17-26
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• 1996

This research was accomplished to evaluate possibility of using paper sludge for the raw materials of wood based panel products. The experimental panels were manufactured by four mixed ratios, the proportion of paper sludge to wood particle: 20:80, 30:70, 40:60, 50:50% (oven dry weight basis) and by three composition types, sludge-particle mixed board, three layered sludge-particle board and three layered particle board. They were tested mechanical (bending strength and internal bond) and physical properties (water absorption, thickness swelling and linear expansion). From the results they were shown that bending strength of mixed and three layered sludge-particle board were decreased with increasing of composition ratios of sludge. And the mechanical and physical properties of the boards of three layered composition types have superior to those of mixed composition type. Although composition ratios of sludge increased, the internal bond strength and dimensional stability of sludge-particle board not decreased quantitatively. We concluded that the mechanical and physical properties of three layered sludge-particle board were similar w those of three layered particle-board (control) made by our laboratory design. Therefore, it was recognized that paper sludge can be used as potential raw material in particle-board manufacturing industry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.1
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• pp.110-115
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• 1994

To investigate the effect of potato lipoxygenase on the farinograph characteristics of wheat flour dough, composite flours containing enzyme-active potato flor (EPF) and hot-ar dried potato flour(HPF) were used. EPF was made by freeze-drying potato tuber. DPF (denaturated potato flour) was prepared by holding EPF at 8$0^{\circ}C$ for 18 hr in a dry oven. The potato flours were added to wheat flour at a level of 10% , respectivley. EPFB (enzyme-active potato flour blends, 90% wheat flour +105 enzyme -active potato flour) containing lipoxygenase activity gave higher farinogram peak time and higher stability values, lower MTI (mixing tolerance index ) and lower weakness values than those of HPFB(hot-air potato flour blends, 90% wheat flour + 10 % hot-air potato flour). Moreover, then lipoxygenase was added to DPFB(denatured potato flour blends , 90% wheat flour + 10% denatured potato flour) at a level of EPFB, it resulted in increasing stability, peak time and decreasing MTI , weakness at a level of EPFB. When the lipoxugenase was added to wheat flour with fumaric acid at alevel of 6.5 $\times$ 10units/g flour, lipoxygenase overcame the deleterious effects that fumaric acid including activated double-bond compounds have at mixing stability. Also the addition of liposxygenase with linoleic acid to defatted wheat flour resulted in the increase in stability and decrease in MTI value compared with those of linoleic acid and defatted wheat flour.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1692-1696
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• 2018

Ferroelectric $BaTiO_3$/poly(vinylidene fluoride) (PVDF) nanocomposite films were successfully prepared by mixing $BaTiO_3$ nano-particles into PVDF solution dissolved in dimethylformamide under ultrasonification. The mixture was casted onto glass petri dish and then annealed at $100^{\circ}C$ for 12 h in vacuum dry oven. Crystal structure and surface morphology of the samples were analyzed by using an X-ray diffraction analysis and a field emission-scanning electron microscope, respectively. The relative dielectric permittivity and loss tangent were determined in the frequency range of 50 Hz to 1 MHz. For the $BaTiO_3/PVDF$ nanocomposites, the entire diffraction peaks match those indicated by standard $BaTiO_3$ perovskite structure. The FE-SEM image reveals the homogeneity of the $BaTiO_3$ nanopowder distribution and also predominant 0-3 connectivity. All results show that the dielectric properties of the nanocomposite films are desirable and the fabrication technique for preparing the $BaTiO_3/PVDF$ nanocomposites has a potential in the electronic applications.

• Journal of the Korea Furniture Society
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• v.20 no.5
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• pp.457-466
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• 2009

This study was carried out to investigate the physical and mechanical properties of 6 hardwoods before and after heat treatment in an effort to produce the high quality industrial lumber product. The results were as follows. Specific gravities of green woods were in range from 0.90 to 1.10. The specific gravities of never treated woods showed higher than those of the heat treated woods. The shrinkage of heat treated woods when green to air & oven dry was significantly low, compared to never treated woods. The compression strengths parallel to grain of heat treated woods showed higher than those of never treated woods. The moduli of rupture (MOR) of never treated and heat treated woods were $176.4N/mm^2{\sim}102.8N/mm^2$ and $100.1N/mm^2{\sim}61.2N/mm^2$ respectively. MORs of heat treated woods showed lower than those of never treated woods. There was no significant change in the modulus of elasticity (MOE) before and after heat treatment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.1
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• pp.65-73
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• 2011

The fibrous raw materials in packaging-grade paper production in Korea were mainly obtained from waste paper. The use of recycled paper has both positive and negative impacts in papermaking process. The primary positive impacts are the environmental protection and manufacturing cost reduction, and the negative impacts are the quality reduction in paper quality and the accumulation of heavy metals and other pollutants in wet- and dry-end process. This study was carried out to consider the optimum acid decomposition system with the highest recovery rate for the analysis of heavy metals in packaging-grade paper. The open digestion system using Kjeldahl apparatus and the closed digestion system using microwave oven for decomposing the organic materials in paper were compared. In both open and closed digestion method, the combination of nitric acid, hydrochloric acid and hydrogen peroxide showed higher recovery rate than using only nitric acid alone because the presence of Cl- ions in hydrochloric acid stabilizes ligand formation with metal ions. KOCC was observed to have the highest heavy metal content among the recycled paper samples. The heavy metal contents decomposed with the closed digestion system were relatively higher than with open digestion system.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.4
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• pp.345-351
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• 2000

The change of crystalline structure of drawn PP filaments were investigated. Samples were treated by isothermally annealed after elevated heating from $20^{\circ}C$. Measurements were carried out with XRD for crystallite size and density gradient tube for crystallinity. Isothermally heat treatment were carried out at the temperature of $100^{\circ}C$, $120^{\circ}C$ and $140^{\circ}C$ for 10min., 30min. and 60min. in dry oven. The isothermal heat treatment after elevated heating from $20^{\circ}C$ were carried out at the temperature of $100^{\circ}C$, $120^{\circ}C$ and $140^{\circ}C$ for 10min., 30min. and 60min. with heating rate of $1^{\circ}C$/min., $5^{\circ}C$/min. and $10^{\circ}C$/min. From the results of this study, it found the following facts. It was found that the crystallinity and crystallite size of (110) plane of sample were increased with increasing of annealed temperature and time. Also crystallinity and crystallite size of samples which were isothermally annealed after elevated heating from $20^{\circ}C$ were higher than those of isohtermally annealed samples.

• Korean journal of food and cookery science
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• v.10 no.3
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• pp.232-237
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• 1994

A Texture profile for frozen pizzas was developed and applied to a comparison of the texture of frozen pizzas heated by conventional and microwave ovens. The texture profile consisted of 29 attributes evaluated at the following five stages: visual and manual. lip feel, first bite, mastication, and swallowing. The microwave pizza tended to be more crisp, dry, and rough but less tender than the conventionally heated pizza. Separate evaluations of the center and edge portions showed differences only in top greasiness, wetness of sauce on palate, moisture release for both types of pizza suggesting that the separated evaluations were not necessarily required. The edge tended to be less greasy and moist than the center possibly because it is more susceptible to overcooking and subsequent drying out.

• Advances in concrete construction
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• v.14 no.3
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• pp.215-225
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• 2022

Thermal comfort and energy conservation are critical issues in the building sector. Energy consumption in the building sector should be reduced whilst enhancing the thermal comfort of occupants. Concrete is the most widely used construction material in buildings. Its thermal conductivity (k-value) has a direct effect on thermal comfort perception. This study aims to find the optimum value of replacing the normal aggregate with lightweight expanded clay aggregate (LECA) under high strengths and low thermal conductivity, density and water absorption. The k-value of the LECA concrete and its physical and mechanical properties have varying correlations. Results indicate that the oven-dry density, compressive strength, splitting tensile strength and k-value of concrete decrease when normal coarse aggregates are replaced with LECA. However, water absorption (initial and final) increases. Thermal conductivity and the physical and mechanical properties have a strong correlation. The statistical optimisation of the experimental data shows that the 39% replacement of normal coarse aggregate by LECA is the optimum value for maximising the compressive and splitting tensile strengths whilst maintaining the k-value, density and water absorption at a minimum.