• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.39-45
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• 1995

The plywoods commonly used as decorative interior materials for the construction are inflammable and so it is a causative factor for making fire accidents, resulting in the destruction of human life and personal properties. Indeed, it is, therefore, required to produce fire-retardant plywoods. In this study, a special grade of defect-free, Kapur plywood was used. Specimens were cut into 3- by 20cm dimensions from 120- by 240- by 0.33-cm panels(thin panel) or 120- by 240- by 0.5-cm panels(thick panel). Some specimens were treated with diammonium phosphate(DAP), but some were not treated with diammonium phosphate to use as control panels. Chemical absorption, drying curves, drying rates and dynamic Young's modulus were investigated. The results were summaries as follows; 1. The specimens were soaked into 19% diammonium phosphate solution by a full cell pressure process and the diammonium phosphate retained in the thin and thick plywoods was 1.409kg/$(30cm)^3$, 1.487kg/$(30cm)^3$, respectively. 2. Diammonium phosphate-treated plywoods were redried with press-drying process at one of either condition dried on the platen($115^{\circ}C$) for a period of time or dried on the platen($50^{\circ}C$) for 3 hrs plus in a dry-oven($30^{\circ}C$) for 24 hrs. or dried on the platen($60^{\circ}C$) for 2 hrs plus in a dry-oven($30^{\circ}C$) for 24 hrs. The drying rate of treated thin specimens dried at $60^{\circ}C$ plus $30^{\circ}C$ and $115^{\circ}C$ only was found to be 0.04 %/min. and 8.53 %/min. Similarly, the drying rate of treated thick specimens were 0.03 %/min. and 6.77 %/min. respectively. 3. It was evident that highly-significantly different drying rate of treated plywoods was observed between plywood thicknesses and platen temperatures and the rate was increased by elevating the platen temperature up to $115^{\circ}C$. Based on the two-way variance analysis, highly significant drying rate was observed from the interaction between plywood thicknesses and platen temperatures. 4. After redrying, the specimens were weighed and reconditioned to a constant weight in a facility maintained temperature ($20^{\circ}C$) and relative humidity(65%) prior to test dynamic Young's modulus. The test revealed that the thin specimens dried at the platen temperature of $50^{\circ}C$, $60^{\circ}C$, $115^{\circ}C$ and untreated specimens showed 1.070E+09 dyne/$cm^2$, 1.156E+09 dyne/$cm^2$, 1.243E+09 dyne/$cm^2$, and 1.052E+09 dyne/$cm^2$, respectively. Likewise, the thick specimens revealed 5.647E+09 dyne/$cm^2$ 5.670E+09 dyne/$cm^2$, 6.395E+09 dyne/$cm^2$ and 5.415E+09 dyne/$cm^2$, respectively. 5. It was evident that significantly different dynamic Young's modulus was observed between the plywood thickness and the platen temperature, but not in the two-way interaction between the plywood thickness${\times}$the platen temperature.

• Asian Journal of Turfgrass Science
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• v.3 no.2
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• pp.77-82
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• 1989

This experiment was carried out to determine the value of turfgrass clippings as a source of protein for animal feed. Levels of crude protein(CP) and in vitro dry matter digestibility(JVDMD) were determined for Korean lawngrass (Zoysia Japonica Steud.) under three levels of nitrogen fertilizer ( 0 , 350 and 700kg ha year and three levels of mowing interval between cuts (lO, 20, and 30 days). Sampling was done on the three-year old turffield on which nitrogen and mowing treatments were Imposed. Clippings were collected after mowing, and CP levels were calculated from a measurement of total N(CP = N >< 6.25) l)y Auto-analyser system-2 procedure and IVDMD by Maeng's method which was partly modified with Tilley and Terry's procedure. With the increased nitrogen legime the CP content of leaf clippings varied from 6.6 to 13.6% and that Of stem clippings from 4 to 10.3%. The CP levels of clippings were directly proportional to the N fertilization rate. The highest CP content was recorded in early July when it was 14.1% at 35OkgN ha -and I 18.l%kgN ha-1 with 10-wcek mowing interval. Mowing interval had little effect on the CP content in both leaf and stem clippings. The level of IVDMD in the Korean lawngrass clippings varied with mowing interval. The highest level measured was 47%, hut this varied during the growing season and occurred in the following order : early summer > summer > fall. This experiment has shown that Korean lawngrass clippings can he helpful source of protein for use in some animal feeds and that a high concentration of CP can occur depending upon N fertllizer and that of I VDM I) upon mowing practices.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.643-648
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• 2005

Near infrared reflectance spectroscopy (NIRS) has become increasingly used as a rapid, accurate method of evaluating some chemical constituents in cereal grains and forages. If samples could be analyzed without drying and grinding, then sample preparation time and costs may be reduced. This study was conducted to develop robust NIRS equations to predict fermentation quality of corn (Zea mays) silage and to select acceptable sample preparation methods for prediction of fermentation products in corn silage by NIRS. Prior to analysis, samples (n = 112) were either oven-dried and ground (OD), frozen in liquid nitrogen and ground (LN) and intact fresh (IF). Samples were scanned from 400 to 2,500 nm with an NIRS 6,500 monochromator. The samples were divided into calibration and validation sets. The spectral data were regressed on a range of dry matter (DM), pH and short chain organic acids using modified multivariate partial least squares (MPLS) analysis that used first and second order derivatives. All chemical analyses were conducted with fresh samples. From these treatments, calibration equations were developed successfully for concentrations of all constituents except butyric acid. Prediction accuracy, represented by standard error of prediction (SEP) and $R^2_{v}$ (variance accounted for in validation set), was slightly better with the LN treatment ($R^2$ 0.75-0.90) than for OD ($R^2$ 0.43-0.81) or IF ($R^2$ 0.62-0.79) treatments. Fermentation characteristics could be successfully predicted by NIRS analysis either with dry or fresh silage. Although statistical results for the OD and IF treatments were the lower than those of LN treatment, intact fresh (IF) treatment may be acceptable when processing is costly or when possible component alterations are expected.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.95-102
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• 2011

Vicker's hardness and pore size distribution of mortar adhered to the recycled coarse aggregate were tested according to the strength level of original concrete of recycled coarse aggregate to find the change of mortar adhered to the recycled coarse aggregate in cement paste. The strength levels of original concrete of recycled coarse aggregate were 25.5MPa, 41.7MPa and 60.1MPa and the aggregates were used at the state of saturated surface dry condition and oven dry condition. The results of this experimentation indicated that the mean value of Vicker's hardness was increased according to age and strength of original concrete of recycled aggregate. Porosity of $100nm{\sim}10{\mu}m$ size was reduced and porosity of 6nm~100nm size was increased in cement paste.

• ANNALS OF ANIMAL RESOURCE SCIENCES
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• v.29 no.4
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• pp.183-190
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• 2018

This study was conducted to evaluate the acceptability of cured cooked boneless chicken drumettes as a raw material for Chuncheon Dakgalbi and to observe its effect on pH, lipid oxidation, volatile basic nitrogen (VBN) content and total viable count (TVC) during refrigerated storage under vacuum. Boneless chicken drumettes were dry cured with a mixed curing agent (0.20% w/w) consisting of sodium chloride (93.1%), sodium nitrite (5.9%) and sodium bicarbonate (1.0%) for 24 h at $2{\pm}2^{\circ}C$. Cured samples were cooked using an oven at $150^{\circ}C$ for 20 min and stored at $5.5{\pm}0.5^{\circ}C$ for 60 days under vacuum. Non-cured cooked sample was used as a control. Sensory evaluation was performed on day 2 of storage using 22 untrained panelists and samples were mixed with Dakgalbi sauce and reheated using a microwave for 2 min. There were no significant differences between control and treatment group on appearance, flavor, texture, juiciness and overall acceptability. Cured cooked boneless chicken drumettes had significantly (p<0.05) higher pH, lower lipid oxidation, VBN and TVC consistently during storage in comparison with control. These results suggest that dry curing could be applied to boneless chicken drumettes as raw material for Chuncheon Dakgalbi and could extend its shelf life during refrigerated storage under vacuum.

• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.31-37
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• 2003

Flat-sawn 32 mm-thick boards of Populus alba×P. glandulosa, one of major plantation species in this country, were dried in conventional, high-temperature and microwave-vacuum (MW/V) kilns. The average green specific gravity of the specimens used in this study was 0.349±0.074. Their average green moisture contents of heartwoods and sapwoods were around 200% and 100%, respectively. From green to oven-dry they shrunk 2.4 and 7.3% in radial and tangential directions, respectively, and there was no discrepancy between heartwoods and sapwoods. It took 65, 35 and 22 hours to dry from green to 10% moisture content in conventional, high-temperature and MW/V kilns, respectively. A colorimetry study showed that the surface color of the specimens dried in a MW/V kiln was clearer and lighter than those in other kilns.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.221-230
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• 2023

The liquefaction of soil occurs when a soil loses strength and stiffness because of applied stress, such as an earthquake or other changes in stress conditions that result in a loss of cohesion. Hence, a method for improving the strength of liquefiable soil needs to be developed. Many techniques have been presented for their possible applications to mitigate liquefiable soil. Recently, alternative methods using biopolymers (such as xanthan gum, guar gum, and gellan gum), nontraditional additives, have been introduced to stabilize fine-grained soils. However, no studies have been done on the use of carrageenan as a biopolymer for soil improvement. Due to of its rheological and chemical structure, carrageenan may have the potential for use as a biopolymer for soil improvement. This research aims to investigate the effect of adding carrageenan on the soil strength of treated liquefiable soil. The biopolymers used for comparison are carrageenan (as a novel biopolymer), xanthan gum, and guar gum. Then, sand samples were made in cylindrical molds (5 cm × 10 cm) by the dry mixing method. The amount of each biopolymer was 1%, 3%, and 5% of the total sample volume with a moisture content of 20%, and the samples were cured for seven days. In terms of observing the effect of temperature on the carrageenan-treated soil, several samples were prepared with dry sand that was heated in an oven at various temperatures (i.e., 20℃ to 75℃) before mixing. The samples were tested with the direct shear test, UCS test, and SEM test. It can increase the cohesion value of liquefiable soil by 22% to 60% compared to untreated soil. It also made the characteristics of the liquefiable increase by 60% to 92% from very loose sandy soil (i.e., ϕ=29°) to very dense sandy soil. Carrageenan was also shown to have a significant effect on the compressive strength and to exceed the liquefaction limit. Based on the results, carrageenan was found to have the potential for use as an alternative biopolymer.

• Journal of Korean Society of Forest Science
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• v.57 no.1
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• pp.32-38
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• 1982

This study was carried out to examine the possibility to replace imported wheat flour with taro. Taro and wheat flour were used for the extenders after oven drying($100{\pm}3^{\circ}C$)and pulverized into 80-100mesh minute powder by laboratory willey mill. Urea- and phenol-formaldehyde resin adhesives were used for plywood manufacture, and the extending materials mixed with the extension at the ratio of 10, 20, 30, and 50% to each resin solution. The results obtained at this study were summarized as follows; 1) In dry and wet shear strength of urea-formaldehyde resin adhesive, taro showed very excellent bonding strength compared with wheat flour in all extending ratio. Therefore taro showed the possibility that be usable to taro in place of wheat flour. 2) In dry and wet shear strength of phenol-formaldehyde resin adhesive, in general, wheat flour showed higher bonding strength than taro. But in dry shear strength, taro showed higher shear strength than wheat flour in 30 and 50% extension.

• Journal of the Korea Furniture Society
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• v.21 no.1
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• pp.62-71
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• 2010

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 object of the research was to design living products with heat treated woods. The results were as follows. Specific gravities of green woods were in range from 0.87 to 1.12. 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 $170.37N/mm^2~107.07N/mm^2$ and $122.78N/mm^2~61.27N/mm^2$ respectively. MORs of heat treated woods showed lower than those of never treated woods. The modulus of elasticity (MOE) of heat treated woods showed higher than those of never treated woods.

• Journal of the Korean Wood Science and Technology
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• v.18 no.3
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• pp.6-16
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• 1990

The objectives of this study were to investigate the relative effects of specific gravity and particle size on internal bond and tensile strengths and fracture toughness of particleboard and to compare mechanical strength with fracture toughness. The particleboard was manufactured with three different particle sizes at specific gravity levels of 0.6, 0.7, and 0.8 with a resin content of 10% based on oven dry weight. The results were summarized as follows: 1. Internal bond strength. fracture toughness in internal bond test. maximum tensile strength, and fracture toughness in tension test increased with the increase of specific gravity of particleboard. 2. As partcle size increased, internal bond strength, fracture toughness. maximum tensile strength. and fracture toughness in tension test increased. 3. The maximum tensile strength and fracture toughness appeared to be in a direct relationship, and then maximum tensile strength could be used for predicition of fracture toughness for tension test. 4. The fracture toughness in internal bond test was somewhat independent on induced crack length.