• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.371-377
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• 1998

The effect of epoxy resin on the water stability of HAC/PVA based MDF cement composite were stu-died through the three different forming methods calendering extruding and warm pressing. In prexing step the epoxy resin was added in 5-15wt% of cement weight. The 3-point flexural strength of each dry and wet specimen which were immersed in water during 3. 7, 14 days was estmated and the mi-crostructural change of epoxy resin-added MDF cement composite due to water immersion was charac-terized by scanning electron microscopy. As the addition amount of epoxy resin the im-provement of water stability of MDF cement composite was achieved in most case. Especially through the warm press forming method the effectiveness of epoxy resin addition to the water stability was enhanced. When the epoxy resin was added by 5wt% to 7wt% the optimum flexural strength and water stability

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.617-622
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• 1992

In order to study on the effect of SiC whisker in flexural strength characterization of macro defect-free (MDF) cement composites, which composed of high alumina cement and polyvinyl alcohol, microstructural characterization of the composite specimens fabricated by the addition of SiC whiskers was investigated. Microproes are created around the SiC whisker, MDF cement didn't react with the SiC whisker. However, flexural strength of the composites have been improved. Fracture morphology of the composites, presents mainly intergranular type fracture passing around the unhydrated particles and siC whiskers, and partially transgranular type fracture. The main strengthening mechanisms of the MDF cement composites reinforced with SiC whiskers are characterized by crack deflection, microcracking, and bridging of cracks.

• International Journal of Reliability and Applications
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• v.4 no.4
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• pp.157-170
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• 2003

In this paper we apply statistical reliability tools to manage and seek improvements in the strengths of medium density fiberboard (MDF). As a part of the MDF manufacturing process, the product undergoes destructive testing at various intervals to determine compliance with customer′s specifications. Workers perform these tests over sampled cross sections of the MDF panel to measure the internal bond (IB) in pounds per square inches until failure. We explore both graphically and statistically this "pressure-to-failure" of MDF. Also, we briefly comment on reducing sources of variability in the IB of MDF.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.254-261
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• 2023

The purpose of this study was to investigate the effects of 8-week resistance training on muscle fatigue in men in their 50s and 30s. A total of 16 subjects (8 in their 30s and 8 in their 50s) were recruited, and moderate-intensity resistance exercise was conducted three times a week for eight weeks. EMG was measured before and after 8 week resistance training. Before 8 weeks exercise, MDF of pectoralis major significantly decreased in all groups, and MDF of triceps brachii significantly decreased only in the 30s group. After 8 weeks of exercise, MDF of pectoralis major significantly decreased in all groups, and MDF of triceps brachii significantly decreased only in the 30s group. The fatigue index before and after the 8-week exercise was changed only in the pectoralis major, and significantly decreased in the 30s group. As a result, the muscle fatigue level among the resistance exercises of men in their 50s may be similar to that of men in their 30s, and muscle fatigue can be reduced by 8 weeks of exercise.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.256-260
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• 2014

Interior of the building is used as a MDF plywood if there is a fire in order to delay the ignition, flame retardant paint, flame retardant solution and flame retardant film are being handled by the flame retardant. Combustion characteristics anf flame retardant performance results can be summarized as follows: General film with a sample showed that short of the criteria in terms of carbonation area, and the results of flame retardant paint, flame retardant solution and flame retardant film products satisfied the criteria. Toxic gases generated in the combustion process results in a film samples using a high incidence of carbon monoxide and the creation of a smoke could be seen. This confirm that is estimated that result from incomplete combustion of PVC film that attach, and displays high toxicity index and hazard class relatively.

• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.41-45
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• 2003

In this study, woodceramics were made from MDF with various resin impregnation rate. To investigate the change of surface temperature of woodceramics, the impregnated MDF was burned at the temp. 600, 800, 1,000, 1,200℃. Surface temperature of woodceramics was increased as impregnation rate and burning temperature was increased. The specimen burned at 800℃ was lower than others. Change of temperature under given temperature increased as time passed and it showed more increased in temperature at burning temperature of 1,200℃. Change of surface temperature increased when floor temperature increased and the temperature was 49.2℃ at 70℃ in floor temperature of 1,200℃ specimen. The decent in surface temperature of woodceramics was the fastest decrease at the burning temperature of 800℃ specimen.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.266-272
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• 2021

The aboveground biomass (AGB) was estimated in mixed dipterocarp forests (MDF), peat swamp forests (PSF), and heath forests (HF) in Brunei Darussalam. A total of 81 (20 m×20 m) plots were established for MDF, PSF, and HF in three regions. The diameter at breast height(DBH) of all live trees (DBH≥10 cm) was measured within the plots. The AGB was calculated using an allometric equation with the measured DBH. The AGB(Mg ha^-1) for MDF, PSF, and HF was 603.3±159.9, 305.9±23.4, and 284.3±19.3, respectively, and was significantly different among the forest types (p<0.05). The greater AGB in MDF than those in PSF and HF was due to the presence of emergent trees in MDF. The results showed that the number of emergent trees varied by forest type. Consequently, the appearance of the emergent trees could be one of the main factors affecting AGB in Southeast Asia's tropical rain forests.

• KSBB Journal
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• v.30 no.6
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• pp.332-338
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• 2015

The objective of this study was designed to determine the possibility of bioethanol production from wasted medium density fiberboard (wMDF). We were investigated the enzymatic saccharification characteristics using the enzyme (Cellic CTec3) after pretreatment with sodium chlorite. According to the component analysis results, the lignin contents before and after the pretreatment of wMDF (milling using sieve size of $1,000{\mu}m$) was significantly reduced from 31.13% to 4.11%. Therefore, delignification ratio of pretreated wMDF was found to be up to about 87-89% depending on the sieve size. And we were tested to compare the saccharification ratio according to the sieve size of wMDF ($1,000{\mu}m$, $200{\mu}m$), but it was no significance depending on the sieve size. When enzyme dosage was 5% based on the substrate concentration, enzymatic saccharification ratio was obtained up to 70% by maintaining at $50^{\circ}C$ for 72 hours. We could made the substrate concentration of pretreated wMDF ($1,000{\mu}m$) up to 12% and then enzymatic saccharification ratio was 76.8%, also contents of glucose and xylose were analyzed to 77,750 and 14,637 mg/L, respectively.

• Physical Therapy Korea
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• v.8 no.3
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• pp.63-76
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• 2001

Many studies have shown that the initial median frequency (MDF) and slope correlate with the muscle fiber composition. This study tested the hypothesis that the initial MDF and slope are fixed, regardless of the interval at which data are collected. MDF data using moving fast Fourier transformation of EMG signals, following local fatigue induced by isotonic exercise, were obtained. An inverse FFT was used to eliminate noise, and characteristic decreasing regression lines were obtained. The regression analysis was done in three different periods, the first one third, first half, and full period, looking at variance in the initial MDF, slope, and fatigue index. Data from surface EMG signals during fatiguing isotonic exercise of the biceps brachii and vastus lateralis in 20 normal subjects were collected. The loads tested were 30% and 60% maximum voluntary contraction (MVC) in the biceps brachii and 40% and 80% MVC in the vastus lateralis. The rate was 25 flexions per minute. There were no significant differences in the initial MDF or slope during the early or full periods of the regression, but there was a significant difference in the fatigue index. Therefore, to observe the change in the initial MDF and slope of the MDF regression line during isotonic exercise, this study suggest that only the early interval need to be observed.

• Journal of the Korean Wood Science and Technology
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• v.27 no.1
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• pp.64-71
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• 1999

This study was conducted to manufacture MDF panels bonded with PF resins which provide excellent durability and dimensional stability with panels, and to identify benefits and weaknesses of using PF resins for MDF panels that have been manufactured with urea-formaldehyde (UF) resins for interior applications due to its low dimensional stability under moisture conditions. The results showed that the performance of PF-bonded MDF panels satisfied the performance requirement. A six-cycle aging test also revealed that PF-bonded MDF panels had high durability. Thickness swelling after 24 hours submersion in cold water was less than 2 percent, showing good dimentioanl stability. The identified weaknesses of using PF resins were relatively high resin content and long hot-pressing time. An acceptable resin content appeared to be 8 percent which can increase the production cost of PF-bonded MDF panels. The hot-pressing time (7 minutes) used in this study is relatively long compared to that of UF-bonded MDF panels. This result also indicates that hot-pressing process has to be optimized to control various pressing variables.