• Composites Research
• /
• v.15 no.3
• /
• pp.39-44
• /
• 2002

Interfacial properties and microfailure modes or electrodeposition(ED) treated carbon fiber reinforced polyetherimide(PEI) toughened epoxy composites were investigated using microdroplet test. ED was performed to improve the interfacial shear strength(IFSS). As PEI content increased, IFSS increased due to enhanced toughness and plastic deformation of PEI. In the untreated cafe, IFSS Increased with adding PEI content, and IFSS of pure PEI matrix showed the highest. On the other hand, thor ED-treated case IFSS increased with PEI content with rather low improvement rate. In the untreated case, neat epoxy resin appeared brittle microfailure mode, whereas pure PEI matrix exhibited more likely ductile microfailure mode. In the ED-treated case, neat epoxy exhibited more ductile fracture compared to the untreated case. Interfacial properties of epoxy-PEI composite can be affected efficiently by both the control of matrix toughness and ED treatment.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.4
• /
• pp.221-224
• /
• 2013

Effects of ambient temperature on the ac electrical treeing and breakdown behaviors in an epoxy/layered silicate (1 wt%) were carried out in needle-plate electrode geometry. A layered silicate was exfoliated in an epoxy base resin,, using our ac electric field apparatus. To measure the treeing initiation and propagation, and the breakdown rate, constant alternating current (ac) of 10 kV (60 Hz) was applied to the specimen in a needle-plate electrode arrangement, at $30^{\circ}C$, $90^{\circ}C$ or $130^{\circ}C$ of insulating oil bath. At $30^{\circ}C$, the treeing initiation time and the breakdown time in the epoxy/layered silicate (1 wt%) system were 1.4 times higher than those of the neat epoxy resin. At $90^{\circ}C$ (lower than Tg), electrical treeing was initiated in 55 min, and propagated until 1,390 min at the speed of $0.35{\times}10^{-3}mm/min$, which was 4.4 times higher than that at $30^{\circ}C$; however, there was almost no further treeing propagation after 1,390 min. At $130^{\circ}C$ (higher than Tg), electrical treeing was initiated in 44 min, and propagated until 2,000 min at the speed of $0.96{\times}10^{-3}mm/min$. Typical branch type electrical treeing was obtained from the neat epoxy and epoxy/layered silicate at $30^{\circ}C$, while bush type treeing was observed out from the needle tip at $90^{\circ}C$ and $130^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.7
• /
• pp.701-710
• /
• 2013

The purpose of this study is to investigate experimentally the effect of low purity methanol (LPM) on performance and smoke emission characteristics by using a four-cycle, four-cylinder, water-cooled, direct injection diesel engine with EGR system. The experiments are performed by the change of engine load in the engine load ranges of 25 to 100% with an interval of 25% under the constant engine speed of 2000 rpm. The LPM in the fuel blends contained 24.88% water by volume. The blended fuel ratios of diesel oil to LPM are maintained at 100/0, 95/5, 90/10 and 85/15% on the volume basis. In this paper, EGR rates are varied in three conditions of 0, 12.8 and 16.5%. The result shows that the brake power of a blended fuel with 15% LPM is reduced more 11.1% than that of the neat diesel oil at the full load with the EGR rate of 16.5%. At this condition, also, the brake specific fuel consumption (BSFC) is increased by 3.2%, the exhaust gas temperature is decreased by 10.7%, the smoke opacity is decreased by 18.7% and the brake thermal efficiency is increased by 7.3%. The sharp reduction of smoke opacity for a blended fuel with the LPM content of 15% at the full load without EGR system is observed by 68.4% compared with that of the neat diesel oil due to the high oxygen content of LPM.

• Analytical Science and Technology
• /
• v.29 no.2
• /
• pp.85-93
• /
• 2016

This study investigated the possibility of DNA contamination during fingerprint collection when using a fingerprint brush. Two kinds of brushes were selected: powdered brushes and neat (not powdered) brushes. The fingerprints were collected from the tips of all the fingers and near the wrists of both living and deceased persons using the two brushes. Both brushes were analyzed for the DNA contents and profiles. The results obtained confirmed the transfer of DNA onto both brushes, although the results showed that the powdered brushes carried more DNA compared with the neat brushes. More DNA was transferred onto the brushes used on deceased persons than onto the brushes used for living persons. Only partial DNA profiles were obtained from the brushes, which is due to the presence of other sources of DNA on the surfaces of the skin of both living and deceased persons. This phenomenon confirmed the DNA contamination during fingerprint collection when fingerprint brushes were used.

• Transactions on Electrical and Electronic Materials
• /
• v.16 no.5
• /
• pp.260-263
• /
• 2015

Epoxy/micro-sized alumina composite was prepared and the effects of alumina content on the electrical and mechanical properties were investigated in order to develop an insulation material for gas insulated switchgear (GIS). Nano-sized alumina (average particle size: 30 μm) was also incorporated into the epoxy/micro-sized alumina composite. An electrical insulation breakdown strength test was carried out in sphere-sphere electrodes and the data were estimated by Weibull statistical analysis. Tensile strength was measured at a crosshead speed of 10 mm/min using a universal testing machine. Alumina content was varied from 0 wt% to 70 wt%.). As micro-sized alumina content increased, insulation breakdown strength increased until 40 wt% alumina content and decreased after that content. The tensile strength of a neat epoxy system was 82.2 MPa and that value for 60 wt% alumina content was 91.8 MPa, which was 111.7% higher than inthe neat epoxy system. The insulation breakdown strength of micro-sized alumina (60 wt%)/nano-sized alumina (1 phr) glycerol diglycidyl ether (GDE) (1 phr) composite was 54.2 MPa, which was 116% higher than the strength of the system without nano-sized alumina.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.14 no.1
• /
• pp.83-87
• /
• 2008

We have a lot of interest in alternative fuels to provide energy independence from oil producing country and to reduce exhaust emissions for air pollution prevention. Biodiesel, which can be generated from natural renewable sources such as new or used vegetable oils or animal fats, may be used as fuel without change of engine structure in diesel engine of compression ignition engine. In this paper, the test results on specific fuel consumption and exhaust emissions of neat diesel oil and biodiesel blends(10 vol.% biodiesel and 20 vol.% biodiesel) were presented using four stroke, direct injection diesel engine. Especially this biodisel was produced from rape oil at our laboratory by ourselves. This study showed that specific fuel consumption and NOx emission were slightly increased, on the other hand CO emission and Soot were tolerably decreased more in the case of biodiesel blends than neat diesel oil.

• Composites Research
• /
• v.16 no.2
• /
• pp.62-67
• /
• 2003

Interfacial properties and damage sensing for the carbon fiber/epoxy-amine terminated (AT)-polyetherimide (PEI) composite were performed using microdroplet test and electrical resistance measurements. As AT-PEI content increased, the fracture toughness of epoxy-AT-PEI matrix increased, and interfacial shear strength (IFSS) increased due to the improved fracture toughness by energy absorption mechanisms of AT-PEI phase. The microdroplet in the carbon fiber/neat epoxy composite showed brittle microfailure mode. At 15 phr AT-PEI content ductile microfailure mode appeared because of improved fracture toughness. After curing, the change in electrical resistance $\Delta\textrm{R}$) with increasing AT-PEI content increased gradually because of thermal shrinkage. Under cyclic stress, in the neat epoxy case the reaching time until same stress was faster and their slope was higher than those of 15 phr AT-PEI. The result obtained from electrical resistance measurements under curing process and reversible stress/strain was correspondence well with matrix toughness properties.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.9
• /
• pp.1193-1200
• /
• 2001

There are many regulation test methods to be related with engine emissions such as CVS-75, D-13, ECE-15 modes and so on. Most of these modes are consisted of lots of transient conditions that have rapid acceleration, deceleration and cranking modes. In this experimental research, the engine characteristics of cranking, accelerating and power output in a S.I. engine were studied to compare with neat gasoline and alternative fuels of M30 (methanol 30%, aromatic series 32%, non-aromatic 38%) and M50 (methanol 50%, aromatic 30%, non-aromatic 20%) for performance and exhaust emissions. The results show that reformulated methanol fuels are better emissions reduction of 15.7% over than that of neat gasoline fuel especially in HC and CO emissions at cranking mode. And the accelerating performances coincide with the results of distillation curve. CO concentration for M50 fuel is varied in a just little for the condition of slow acceleration. At wide-open throttle condition, brake specific energy consumption of reformulated fuels is increased and thermal efficiency is some what lower than that of gasoline fuel.

• Resources Recycling
• /
• v.8 no.3
• /
• pp.3-8
• /
• 1999

An air-washer was developed in order to remove the soil on the films collected from agricultural use, The washed films were subjected to TGA analysis to measure the residual soil content and DSC analysis to evaluate composition as well as compositional ratro, Mechanical properties of washed films were measured via tensile test ,md the properties of washed films were compared with those of neat resin blend. Major component of air washed films was polyethylene, and compositional ratio was 10:6:3:1 (HDPE:LLDPE:LDPE:EVA). 30 min air-washed films showed 2.1 % of residual soil content, while the water washed films had 1.5%. Tensile properties of washed (air and water) films were almost same as those of neat resin mixture.

• Composites Research
• /
• v.33 no.1
• /
• pp.19-24
• /
• 2020

In this paper, the microwave irradiation process was conducted during the Poly(vinylidene fluoride) (PVDF) nano-composite film fabrication process to analyze how the β-crystalline is increased. TiO₂ was added as a nanoparticle reinforcement to further improve the β-crystalline conformation of the PVDF films by van der Waals force due to the difference of electronegativity between PVDF and the metal oxide nanoparticle. The crystalline conformation of the fabricated films was analyzed by X-ray diffraction and Fourier transform infrared spectroscopy. According to these analysis results, it was confirmed that the microwave irradiation process during the solvent evaporation process increases the crystallinity of the PVDF films, and more β-crystalline can be obtained after additional film stretching process. It was also found that the PVDF nano-composite films with the metal oxide have relatively higher β-crystalline conformation rather than the neat PVDF films.