• Geomechanics and Engineering
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• v.13 no.4
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• pp.585-600
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• 2017

This study deals with simple solutions for a spherical or circular opening excavated in elastic-brittle plastic rock mass compatible with a linear Mohr-Coulomb (M-C) or a nonlinear Hoek-Brown (H-B) yield criterion. Based on total strain approach, the closed-form solutions of stresses and displacement are derived simultaneously for circular and spherical openings using original H-B and M-C yield criteria. Two simple numerical procedures are proposed for the solution of generalized H-B and M-C yield criteria. Based on incremental approach, the similarity solution is derived for circular and spherical openings using generalized H-B and M-C yield criteria. The classical Runge-Kutta method is used to integrate the first-order ordinary differential equations. Using three data sets for M-C and H-B models, the results of the radial displacements, the spreading of the plastic radius with decreasing pressure, and the radial and circumferential stresses in the plastic region are compared. Excellent agreement among the solutions is obtained for all cases of spherical and circular openings. The importance of the use of proper initial values in the similarity solution is discussed.

• Journal of Ecology and Environment
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• v.35 no.3
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• pp.195-201
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• 2012

Seasonal variations in the profile and concentrations of essential oil in Zanthoxylum piperitum were investigated by gas chromatography-mass spectrometry. Seasonal changes in the percentages of the main constituents of the essential oil of both leaves and fruits from Z. piperitum varied. Variations in essential oil yield and the amount of monoterpenes and sesquiterpenes in leaves and fruits at different developmental stages were significant. The characteristic content of essential oil in leaves was determined mainly due to the content of monoterpenes, and that in fruits was determined largely due to the sesquiterpenes. Twenty-nine compounds in the oil from Z. piperitum leaves were detected; the major compounds were ${\beta}$-phellandrene (26.90%), citronella (15.32%), ${\beta}$-myrcene (3.24%), ${\alpha}$-pinene (2.79%), trans-caryophyllene (2.66%), and fanesyl acetate (2.30%). The highest yield of oil (43.89%) in Z. piperitum leaves was obtained in May but decreased gradually beginning in June. The yield of essential oil from Z. piperitum leaves during early periods was higher than that during later periods and usually decreased from early maturation stages to subsequent stages. However, in contrast to leaves, the oil yield in Z. piperitum fruit increased in June, and oil yield later in the season was higher than that earlier in the season. These results indicate that the essential oil produced from Z. piperitum leaves at the early developmental stages was stored in leaves, and might be transferred to fruit at the final developmental stages.

• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.40-45
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• 2005

The principal actions of a flame retardant are to decrease or prevent the formation of volatile products and increase the formation of char layer. Use of flame retardant additives can decrease the overall fire hazard of the product containing them thus leading to an increase in overall fire safety. Although several flame retardants have been developed for use in polymers, many of these are known to increase the amount of smoke and toxic gases generated by them. This paper present a new flame retardant using metal addition flame retardant. For this study, the experiments of flame retardancy conducted are as follows : burning ratio, weight loss rate using TGA-DTA, the measurement of LOI and char yield. And smoke mass concentration and CO yield were measured. The metal addition flame retardant reduced burning ratio and weight loss rate, increased the LOI and yield of char formation with decreased smoke mass concentration and CO yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.201-206
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• 1999

For the mass production of plug seedlings in cultivar ‘Dejima’ potato (Solanum tuberosum L.) the optimal apical cutting diameter for rooting and rapid multiplication of stem cuttings in hydroponics were determined. In addition, the best planting date was predicted to increase tuber yield of plug seedlings at fall cropping in Cheju-Do, Korea. Days to initial rooting decreased as the cutting diameter was reduced. Plant height, leaf number, root length and root weight per plant were favorable as the cutting diameter was small. The ideal cutting diameter was 1-2 mm in this experiment. In the hydroponic cultures, the Japanese standard (JS) nutrient solution was the most effective for multiplication of stem cuttings. It was able to propagate more than 20 times a month from a single mother plant. Viability of plants, which were derived from plug seedlings using stem cuttings, was excellent when transplanted to the field. The number of tubers and tuber yield in both of the plug seedlings and seed potato planting plots were high when planted on 25 August. The number and yield were reduced when planted on 15 August, 5 September and 15 September. The degree of decrease of tuber yield in the plug seedling planting plot however, was lower than that of seed potatoes when the planting date was late. In the case of small tubers (under 30 g), the number of tubers and tuber yield were evidently increased in the seed potato tuber planting plot; the yield of large tuber (over 80g) in the plug seedling planting plot was higher than that of the seed potato. The total tuber yield per plant in the plug seedling planting plot was less than that of the seed potato; therefore, in order to increase tuber yield it was necessary to increase field plant density.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.547-554
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• 2018

Torrefaction is the promising process of pretreating biomass materials to increase the quality of their energy, especially to upgrade the materials' grindability so that it is suitable for a commercial pulverizer machine. In this study, torrefaction of oak, bamboo, oil palm trunk, and rice husk was carried out under different torrefaction temperatures ($300^{\circ}C$, $330^{\circ}C$, and $350^{\circ}C$) and different torrefaction residence times (30, 45, and 60 minutes). Complete characterization of the torrefied biomass, including proximate analysis, calorific value, thermogravimetric analysis, mass yield, energy yield, and grindability properties (Hardgrove Grindability Index) was carried out. Increasing the torrefaction temperature and residence time significantly improved the calorific value, energy density (by reducing the product mass), and grindability of the product. Furthermore, for commercial purposes, the torrefaction conditions that produced the desired grindability properties of the torrefied product were $330^{\circ}C-30minutes$ and $300^{\circ}-45minutes$, and the latter condition produced a higher energy yield for bamboo, oil palm trunk, and rice husk; however, torrefaction of oak did not achieve the targeted grindability property values.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.122-127
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• 1993

This study was conducted to investigate characteristics related to lacquer yield and to evaluate possibility of indirect selection of Rhus verniciflua Stokes. Twenty-four lacquer trees were randomly selected for measuring growth, urushiol content and bark thickness. Urushiol content showed a significant positive correlation with outer bark thickness and secretory canal density at 1% level, and with inner bark thickness at 5% level. Bark thickness and secretory canal density could be used as indicators for high urushiol content within bark and thus for high lacquer yield. Mass selection for high lacquer yield was made based on urushiol content within bark. Sixteen individuals with the highest urushiol content value were selected for breeding. As expected, the selected trees had thicker bark, higher density of secretory canal, better developed secretory canals compare to the non-selected lacquer trees.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.351-354
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• 2001

In this experiment, we tested various nitrogen sources and then culture condition was optimized for industrial applications. The batch culture of Candida magnoliae SR101 grown in a defined medium supplemented with light steep water (LSW) as a sole nitrogen source showed a relatively high yield of erythritol production (53%), which was slightly higher than that using yeast extract as a nitrogen source, while the productivity and cell mass were maintained at similar levels. For the optimization of culture condition, the batch culture was performed. When the concentration of LSW was 65 mL/L in the defined medium containing 250 g/L of glucose, the concentration, yield and productivity of erythritol were 110 g/L, 44%, and 0.66 g/L-hr, respectively. The high yield and comparable productivity obtained with a cheap nitrogen source could be expected as a basis for the mass production of erythritol in the industrial scale.

• Preventive Nutrition and Food Science
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• v.2 no.1
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• pp.66-70
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• 1997

A mixed-culture of Gluconobacter suboxydans IFO 3172 and Saccharomyces uvarum IFO 0751 was per-formed in a synthetic medium. the optimal inculum ratio of G. suboydans and S. uvarum for mixed-culture fermentation was 150:1. The optimum pH, incubation temperature and aeration rate for mixed-culture fer- mentation were 5.0, 3$0^{\circ}C$ and 2.25vvm, reapectively. As a result of batch pure-and mixed-culture fer-mentation, specific growth rate in pure-culture of both strain was lower than that in mixed-culture. The yield of cell mass from S. uvarum exclusively decreased. The growth rate of the mixed-culture was very similar to the pure-culture in the begining of culture, but it has been decreased after 16hrs. In the mean time, S. uvarum in mixed-culture fermentation could grow due to fructose converted, but it could not row in pure-culture fermentation. Thus, the relationship was a sort of commensalism. The kinetic parameters cal-culated through steady-state results during continuous fermentations are as follows :{TEX}$$\mu$_{max1}${/TEX}=0.118({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{1}${/TEX}=0.330(g/L),:{TEX}$$\mu$_{max2}${/TEX}=0.162({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{2}${/TEX}=0.038(g/L). The yield of bacterial cell mass relatively constant, but yield of yest cell mass was gradually decreased.

• Geomechanics and Engineering
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• v.21 no.6
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• pp.527-536
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• 2020

An elastic-plastic solution for cavity expansion problem considering strength degradation, undrained condition and initial anisotropic in-situ stress is established based on the Tresca yield criterion and cavity expansion theory. Assumptions of large-strain for plastic region and small-strain for elastic region are adopted, respectively. The initial in-situ stress state of natural soil mass may be anisotropic caused by consolidation history, and the strength degradation of soil mass is caused by structural damage of soil mass in the process of loading analysis (cavity expansion process). Finally, the published solutions are conducted to verify the suitability of this elastic-plastic solution, and the parametric studies are investigated in order to the significance of this study for in-situ soil test.

• Animal Bioscience
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• v.36 no.5
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• pp.818-828
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• 2023

Objective: The purpose of this study was to analyze the effect of the hydrothermal pretreatment of anaerobic digestion sludge cake (ADSC) of cattle manure on the solubilization of organic matter and the methane yield to improve the anaerobic digestion efficiency of cattle manure collected from the sawdust pens of cattle. Methods: Anaerobic digestion sludge cake of cattle manure was thermally pretreated at 160℃, 180℃, 200℃, and 220℃ by a hydrothermal pressure reactor, and the biochemical methane potential of ADSC hydrolysate was analyzed. Methane yield recovered by the hydrothermal pretreatment of ADCS was estimated based on mass balance. Results: The chemical oxygen demand solubilization degree (COD_s) of the hydrothermal hydrolysate increased to 63.56%, 67.13%, 70.07%, and 66.14% at the hydrothermal reaction temperatures of 160℃, 180℃, 200℃, and 220℃, respectively. Considering the volatile solids content obtained after the hydrothermal pretreatment, the methane of 10.2 Nm³/ton-ADSC was recovered from ADSC of 1.0 ton, and methane yields of ADSC hydrolysate increased to 15.6, 18.0, 17.4, and 17.2 Nm³/ton-ADSC. Conclusion: Therefore, the optimal hydrothermal reaction temperature that yielded the maximum methane yield was 180℃ based on mass balance, and the methane yield from cattle manure containing sawdust was improved by the hydrothermal pretreatment of ADSC.