• Journal of the Korean Wood Science and Technology
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• v.49 no.1
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• pp.14-22
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• 2021

The objective of this study was to investigate the effect of alkali-washing with different sodium hydroxide concentrations on the chemical compositions of steam-treated Betung bamboo strand. Strands were subjected to steam treatment at 126 ℃ for 1 h under 0.14 MPa pressure and followed by washing with 1-5% sodium hydroxide solution for 30 sec. The alteration of structural and non-structural chemical components content of bamboo strands was evaluated. Steam and washing treatments with various concentrations of sodium hydroxide solution considerably reduced the extractive content of bamboo strands, and the cell wall chemical components of the strand in the small degree. FTIR analysis showed noticeable changes in peaks related to hemicellulose and lignin. The relative crystallinity increased significantly after steam and washing treatment with sodium hydroxide up to 3% concentration. SEM Images showed smooth and clean strands surface after washing with 3% sodium hydroxide.

• Advances in concrete construction
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• v.11 no.5
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• pp.367-374
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• 2021

The present study investigated the effect of the combined carbonation and steam curing on the physicochemical properties and CO₂ uptake of the Portland cement concrete. Four different curing regimes were adopted during the initial 10 h of curing to evaluate the potential of carbonation curing as an alternative to conventional steam curing in the precast concrete industry from environmental and practical viewpoints. Four combinations of carbonation and steam curing conditions were applied as curing regimes to the samples at an early age. The test results indicated that the samples treated with the combined carbonation and steam curing exhibited higher early strength development compared to the other samples, signifying that carbonation curing can reduce the production time of precast concrete. Furthermore, the CO₂ uptake capacity of the samples was calculated and found to be as high as 18% with respect to the mass of the paste samples. Hence, the simultaneous utilization of steam and CO₂ for the fabrication of precast concrete members has the potential to make precast concrete greener and more cost-effective.

• Food Science and Preservation
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• v.22 no.3
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• pp.385-391
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• 2015

This study was conducted to develop a spray-dried garlic chives (Allium tuberosum) powder and to evaluate its quality characteristics depending on the treatment of steam blanching pretreatment $100^{\circ}C$, 3 min) and the addition of forming agents (dextrin (DE=10), ${\beta}$-cyclodextrin) during process. The steam blanching pretreatment showed an increase in $L^*$ value while a decrease in $-a^*$, $b^*$, $C^*$, and $h^o$ values of the powder. Moisture content and water soluble index were not affected by the treatment of steam blanching and the addition of forming agents, whereas the particle diameter was the smallest in the steam blanching treatment and dextrin addition. Chlorophyll, phenolic compound, and vitamin C content, and DPPH radical scavenging activity of non-pretreated powder were significantly higher than those of the steam blanching treated powders. However, there was no significant difference between the two forming agents. The sensory acceptability (color, smell, and overall acceptability) of powder treated with steam blanching were significantly higher than those of non-pretreated powders. Therefore, the steam blanching pretreatment of fresh garlic chives affected on the better quality characteristics of the spray-dried powders when compared with non-pretreated powder though it adversely affected the natural chemical quality of fresh garlic chives.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.278-282
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• 2012

The objectives of this study was to compare the physicochemical properties and antioxidant activities of raw, microwave-treated, steam-treated and high temperature and pressure-treated garlic. The hardness and strength of microwave-treated and steam-treated garlic decreased compared to raw garlic. The hardness and softness increased but strength decreased in dried garlic-treated at $60^{\circ}C$ for 48 hr. The reducing sugar content of raw garlic was 0.041 g/100 g, and reducing sugar content of high temperature and pressure-treated garlic increased temperature. Total polyphenol content of microwave-treated and steam-treated decreased compared to raw garlic, while that of high temperature and pressure-treated increased with increasing temperature. $IC_{50}$ value of the electron donating ability of raw garlic was 3.07 mg/mL, and the highest $IC_{50}$ value was 2.16 mg/mL for microwave-treated garlic at the 4 min. The ABTS radical scavenging activity of raw garlic was 40.94 mg AEAC/mL, and the highest AEAC value was 76.51 mg AEAC/mL with high temperature and pressure-treated garlic at $150^{\circ}C$ at the 2 hr.

• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.30-36
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• 1993

Wood chips of oak (Quercus mongolica) and larch (Larix leptolepis) were treated with a relatively low pressure steam(10~20 kg/$cm^2$) for 10~20 min (first-stage),and then increased pressure up to 30kg/$cm^2$ for 30 second (second-stage), and steam pressure was released intentionally to air. Main components of exploded wood were separated with 1% NaOH and hot water-methanol. In this work, the more effective low pressure explosion condition and separation method of wood main component were investigated. The results can be summarized as follows; 1. The yields of exploded wood were generally decreased with increasing steam pressure and reaction time. 2. The proper condition of steam explosion in low pressure for the separation of wood main components was 15kg/$cm^2$-10 min, in oak wood and 20kg/$cm^2$-10 min., then 30kg/$cm^2$-0.5 min, in larch wood. 3. The 23% of elude hemicellulose was obtained from the exploded oak wood which was treated with optimal condition. 4. In the case of hot water-methanol extraction, the ratio of delignification was 14~23% in the exploded larch wood and 42~55% in the exploded oak wood. 5. The methanol was more effective than 1% sodium hydroxide solution for extraction of lignin from exploded wood.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.874-881
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• 2015

In the food industry, thermal treatment is an important process for extending shelf-life of foods. However, heating process affects the physicochemical, nutritional, and microbial properties of foodstuff such as color, texture, pH, and proximate compositions. This study was conducted to select an optimal thermal treatment by observing physicochemical, nutritional, and microbial effects of shiitake mushrooms with different thermal treatment methods. Shiitake mushrooms were washed and sliced equally ($5cm{\times}0.5cm{\times}0.5cm$) and then heat-treated by three methods. Samples were heated in $100^{\circ}C$ boiling water, steamed for 10 min, or pan fried at $130^{\circ}C$ for 4 min. Total color difference values showed significantly increasing tendency with treatment time. For pH values, boiling water-treated mushrooms showed increasing tendency according to increased thermal treatment. For the results of hardness, boiling water or pan frying-treated mushrooms showed reduced tendency within 1 min. In the case of steam-treated mushrooms, hardness values were maintained for 1 min. Organic acid contents of steam-treated sample showed the lowest value among treatments. For microbial counts, steam-treated samples for 3 min showed the lowest value. Consequently, the results of this study suggest that steam treatment could be the optimal thermal treatment to minimize quality loss of shiitake mushrooms.

• Journal of the Korean Wood Science and Technology
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• v.40 no.4
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• pp.257-267
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• 2012

In this study, the method for heat treating wood using superheated steam (SHS) was designed and applied. The physical and mechanical properties of Korean Pine (Pinus koraiensis Siebold & Zucc.) lumber heat-treated by SHS at $170^{\circ}C$ and 0.4 MPa for 10 hours were compared with those of non-treated and normal heat-treated wood. The amount of adsorbed water and equilibrium moisture content of the SHS treated wood were lower than non-treated wood. On the other hand the compressive strength parallel to grain and the bending strength of SHS treated wood were higher than those of non-treated wood. The hygroscopicity of SHS treated wood was similar to normal heat treated wood at $220^{\circ}C$. Internal checks that often occur during normal heat treatment were not developed at SHS treatment. Also, SHS treatment are effective in control of internal checks occurrence and resin exudation.

• Journal of the Korean Wood Science and Technology
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• v.20 no.3
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• pp.11-20
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• 1992

Steam explosion is one of the most effective pretreatment for fractionating wood. This leads to the total utilization of wood basic components; cellulose, hemicellulose and lignin. The amount of sugar and lignin extracted with the hot water method was very low. The lignin content of residues after extraction with using a sodium hydroxide treatment, increased delignification of carbohydrate as the concentration of alkali was increased. Oak, pretreated with steam exploded at 25kg/$cm^2$ for 6 min. then 1% alkali for 2hrs. showed a delignification rate up to 95%. A sodium chlorite treatment of steam exploded pine and oak also afforded a high deligninfication effect. Pine, treated 10% sodium chlorite for 2hrs. showed high delignification. However, by using a sodium hydroxide treatment, a 2% retreatment for Ihr. after a 2% for 2hrs. afforded remarkable delignification effect on exploded wood at 30kg/$cm^2$ for 9min. and at 35kg/$cm^2$ for 3-6min. In oak, an initial 2hrs. treatment of 2% sodium chlorite was followed by a second 2hrs. treatment at 10%. This showed a delignification rate of 96%.

• Journal of computational fluids engineering
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• v.11 no.2 s.33
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• pp.8-18
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• 2006

A CFD benchmark calculation for a steam blowdown test was performed for 30 seconds to develop the methodology of numerical analysis for the thermal mixing between steam and subcooled water. In the CFD analysis, the grid model simulating the sparger and the IRWST pool were developed by the axisymmetric condition and then the steam condensation phenomena by a direct contact was modelled by the so-called condensation region model. Thermal mixing phenomenon in the subcooled water tank was treated as an incompressible flow, a free surface flow between the air and the water, a turbulent flow, and a buoyancy flow. The comparison of the CFD results with the test data showed a good agreement as a whole, but a small temperature difference was locally found at some locations. The commercial CFD code of CFX4.4 together with the condensation region model can simulate the thermal mixing behavior reasonably well when a sufficient number of mesh distribution and a proper numerical method are adopted.

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.872-882
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• 2017

The objective of this study was to evaluate the properties of bamboo oriented strand board (B-OSB) from andong (Gigantochloa psedoarundinacea) and betung (Dendrocalamus asper) with and without steam treatment. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure. The extractive content of bamboo strands before and after steam treatment were determined according to a standard (TAPPI T 204 om-88). Three-layer B-OSB with the core layer perpendicular to the surface and back layers were formed and binded with 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of the boards were conducted in accordance with the JIS A 5908:2003 standard. The results showed that steam treatment of bamboo strands significantly reduced the extractive content. Steam treatment tended to increase the dimensional stability and mechanical properties of B-OSB from andong and betung. The results showed that the dimensional stability and bending strength of B-OSB from betung was higher than those of andong. The internal bond strength of B-OSB from andong was higher than betung owing to a greater amount of extractives dissolved during the steam treatment.