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Damper is frequently used to suppress panel vibration and related vehicle interior noise. Unlike an unconstrained damper, a method to find material properties of a constrained damper is more complicated. This study presents a verified method for obtaining material properties of a constrained asymmetrical damper. The most important material parameters of this constrained damper are shear modulus, shear factor, and of course damping loss factor. The paper provides newly corrected equations to give proper numerical values of these parameters. The difference of natural frequencies between the test and the simulation using the estimated values is about 2 %, which shows that the estimation method is correctly presented. Important characteristics such as shear motion and wavelength of a composite beam constrained by a damper are also investigated. Finally, vibration response of a vehicle roof with a constrained damper is measured and is compared to the simulation. It is noticed that the correlation is much improved, comparing with the simulation based on old material properties.

As part of efforts to fabricate FeMnAlC lightweight steels suitable for high-temperature applications, the influence of Nb addition on the microstructure and tensile deformation behaviors has been investigated. Electron backscattered diffraction analysis showed that Fe–20Mn–8Al–1.0C base steel consisted of a full austenite matrix after solution treatment, and the addition of 0.1 wt pct Nb resulted in grain refinement from 56 to 23 μm without significant changes in the microstructure. After aging treatment at 550 °C for 1 hour, significant hardening occurred (base steel: 257 → 392 HV, Nb-added steel: 273 → 359 HV) by the precipitation of nanosized κ-carbides with sizes of 2 to 6 nm. A higher strain-hardening rate at 400 °C by Nb addition was clearly brought about by the mutual interaction of dislocations with κ-carbides (through both shearing and Orowan bypassing mechanisms). The nanoindentation results and the calculation of the strength increment indicated that Nb addition led to a smaller hardening by κ-carbide precipitation. In terms of the microstructural evolution by thermal exposure time (100 to 5000 hours at 400 °C), it was first found that the intensive slip band impingement at grain boundaries occurred in these lightweight steels, but Nb addition effectively inhibited the significant reduction in ductility by suppressing the formation of slip bands. The effect of Nb addition is discussed in terms of the collaborative effects of grain refinement, κ-carbide precipitation, and microstructural stability.

The general bone anabolic effect of photobiomodulation (PBM) is largely accepted. As a result, PBM therapy is expected to be beneficial in the medical fields of dentistry and bone healing. However, most of the previous in vitro studies on PBM and bone metabolism were performed with single-cell cultures of osteoclast-lineage cells or osteoblast-lineage cells. In the present study, the bone-modulating effects of PBM were evaluated in an in vitro osteoblast/osteoclast co-culture system. Mouse bone marrow-derived macrophages (BMMs) and mouse calvarial pre-osteoblasts cells were purified and used as precursor cells for osteoclasts and osteoblasts, respectively. The PBM effects on single-cell culture of osteoclasts or osteoblasts as well as co-culture were examined by 1.2 J/cm2 low-level Ga-Al-As laser (λ = 808 ± 3 nm, 80 mW, and 80 mA; spot size, 1cm2; NDLux, Seoul, Korea) irradiation for 30 s at daily intervals throughout culture period. At the end of culture, the osteoclast differentiation and osteoblast differentiation were assessed by TRAP staining and ALP staining, respectively. The expressions of osteoclastogenic cytokines were evaluated by RT-PCR and Western blot analyses. Under the single-cell culture condition, PBM enhanced osteoblast differentiation but had minor effects on osteoclast differentiation. However, in the co-culture condition, its osteoblastogenic effect was maintained, and osteoclast differentiation was substantially reduced. Subsequent RT-PCR analyses and western blot results revealed marked reduction in receptor activator of NF-κB ligand (RANKL) expression and elevation in osteoprotegerin (OPG) expression by PBM in co-cultured cells. More importantly, these alterations in RANKL/OPG levels were not observed under the single-cell culture conditions. Our results highlight the different effects of PBM on bone cells based on culture conditions. Further, our findings suggest the indirect anti-osteoclastogenic effect of PBM, which is accompanied by a decrease in RANKL expression and an increase in OPG expression.

There is a great demand for a dispersion evaluation method that can be applied even when a nano-sized filler is incorporated, that can evaluate a three-dimensional (3D) quantitative dispersion of a composite material, and that is not expensive and time consuming. Here, we proposed light-intensity dispersion index (LDI) to quantitatively evaluate the dispersion based on the light scattering distribution on divided optical microscopy (OM) images. Difference in the light-intensity is determined by the dispersion and agglomeration of the filler in the polymer matrix; therefore, the smaller the distribution and the number of peaks of light-intensity, the more uniform the dispersion. The reliability of the developed LDI was improved by introducing an agglomeration size weighting factor. Furthermore, the validity of the LDI was also verified in comparison with the experimental results. In conclusion, we have successfully developed a method for the 3D quantitative dispersion evaluation of nanocomposites with minimal cost and time consumption.

There is growing interest in carbon fibre fabric reinforced polymer (CFRP) composites based on a thermoplastic matrix, which is easy to rapidly produce, repair or recycle. To expand the applications of thermoplastic CFRP composites, we propose a process for fabricating conductive CFRP composites with improved electrical and thermal conductivities using an in-situ polymerizable and thermoplastic cyclic butylene terephthalate oligomer matrix, which can induce good impregnation of carbon fibres and a high dispersion of nanocarbon fillers. Under optimal processing conditions, the surface resistivity below the order of 10+10 Ω/sq, which can enable electrostatic powder painting application for automotive outer panels, can be induced with a low nanofiller content of 1 wt%. Furthermore, CFRP composites containing 20 wt% graphene nanoplatelets (GNPs) were found to exhibit an excellent thermal conductivity of 13.7 W/m·K. Incorporating multi-walled carbon nanotubes into CFRP composites is more advantageous for improving electrical conductivity, whereas incorporating GNPs is more beneficial for enhancing thermal conductivity. It is possible to fabricate the developed thermoplastic CFRP composites within 2 min. The proposed composites have sufficient potential for use in automotive outer panels, engine blocks and other mechanical components that require conductive characteristics.

Dept. of Life Science, Chung-Ang University, KoreaABSTRACTThe purpose of this study was to investigate the effects of mustard, which contains allyl isothiocyanate, on ruminal fermentation and methane emission in vitro. To this end, diluted ruminal fluid(30ml) was incubated anaerobically at 39for 6, 12, and 24h with or without seeds or powdered mustard. Either mustard seed or powdered mustard was weighed and serially(0, 3.33, 5.00, 6.67, and 8.33g/L) mixed with ruminal fluid. Ammonia-N was increased(P

The objectives of experiments were to compare directly the effects of synchrony of slowly fermented (corn and corn gluten meal; C-CGM) and of rapidly fermented ingredients (barley and soybean meal; B-SBM) in the rumen on starch disappearances in gastrointestinal tracts (Experiment 1) and growth performance (Experiment 2) of Hanwoo steers in the feedlot barn. In experiment 1, four Hanwoo steers (288 ± 21 kg) fitted with ruminal and "T" shaped duodenal cannula were placed in one pen with Calan gate and assigned randomly to a duplicate 2 × 2 Latin square design. In experiment 2, eight intact Hanwoo steers (311 ± 8 kg) were assigned randomly to one of two pens with Calan gate to evaluate the effect of the same diets as like in experiment 1 on growth performance. There were no differences in ruminal pH, ammonia and total VFA concentrations between treatments. Percentage of apparent ruminal starch disappearance was 33.3% unit lower (p

This study was conducted to evaluate the effects of saponin contained plant extracts on in vitro rumen fermentation characteristics and methane production. Ruminal fluid was collected from rumen cannulated Hanwoo steers fed rice straw and concentrate (5:5). Collected rumen fluids, corn starch and buffer including saponin contained plant extracts (ginseng, Ogapi, soapwort, tea plant and yucca; 0.5%/15 ml) were incubated at 39 for 24 h. All incubations were repeated five times. Rumen pH in all treatments was lower (p

Present experiment was carried out to determine maintenance energy requirements for growing Hanwoo steers. Six Hanwoo steers (BW = kg) were used in two 3 3 latin square design with three different energy intake levels; TDN 1.70 kg (Low), 2.05 kg (Medium), 2.80 kg (High), respectively, based on the Korean Feeding Standards. Each period lasted 18 days including a 14-day adaptation and a 4-day measuring period. The steers were in the head hood chamber system (one cattle per chamber) during each measuring time to measure heat and methane production for 1 day. Dry matter intake was 2,058, 3,256 and 3,881 g/day for Low, Medium and High TDN, respectively. Increase in energy intake did not affect digestibilities of dry matter, crude protein, crude fiber, crude fat, NDF, ADF and nitrogen-free extract. Gross energy intake averaged 180.21, 292.74 and 337.15 kcal/ for Low, Medium and High TDN, respectively. Energy loss was 28.7% in feces and 2.1% in urine of gross energy intake. Further, energy loss from methane produced during rumen fermentation was 6~8.3%, while body heat loss averaged 34~60%. Intercept of regression equation between ME intake and retained energy indicated that the energy requirement was 109.84 kcal ME/.

This study was carried out to optimize dyeing conditions of unripe Citrus Unshiu extract on silk fabric and to evaluate antimicrobial activity of the dyed fabric for its potential use as a functional natural dye. Unripe fruits of Citrus Unshiu in Jeju Island, Korea, extracted in 80 % Ethanol solution to final solid dye powder were dyed on silk fabric under a variety of conditions such as dye bath concentrations, temperature, and dyeing duration together with mordanting. Dyeing fastness properties to washing, rubbing, perspiration, and light were tested and the antimicrobial activities of the dyed fabric against Staphylococcus aureus and Klebsiella pneumoniae were investigated quantitatively. As results, the fabric showed the maximum dye uptake (K/S) under the conditions of 80 °C for temperature, 30 min for duration, and 600 % (o.w.f.) for dye concentration. Both pre- and post-mordanting seemed not to be effective on increasing K/S values of the dyed silk fabrics under the optimum dyeing conditions. Fastness ratings to washing, rubbing, and perspiration were all very good (4–5 grades) for both 300 and 600 % dyed silk fabrics. Excellent antimicrobial activities over 99 % reduction rate against two both bacteria were exhibited for all of dyed fabrics undergone more than 300 % of dye concentration. From these results, it was concluded that the dye concentration of 300 % of unripe Citrus Unshiu could be employed to produce antimicrobial silk fabric. Furthermore, to get more saturated shades on the fabric by the citrus, higher dye concentration such as 600 % was available as well.

Multi-layered TiO2 nanostructured films were fabricated to improve the light harvest efficiency of the dye-adsorbed TiO2 electrode in dye-sensitized solar cells (DSSCs) by light scattering. Three different structures of TiO2 electrodes, with layers consisting of TiO2 pastes with average diameters of 9, 20, and 300 nm, respectively, were fabricated and their photovoltaic effects on the DSSC devices were investigated. By utilizing the multi-layered TiO2 electrode constructed using the three different TiO2 pastes, the overall power conversion efficiency of the DSSC devices in the PEG-based electrolyte was increased to 5.24% under irradiation of 100 mW/cm2 at AM 1.5.