• Composites Research
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• v.29 no.3
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• pp.98-103
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• 2016

This paper deals with the fabrication and verification of the microwave absorbing structure using semiconductive fiber reinforced composite. Two kinds of fiber were used to fabricate composites. Electromagnetic properties of the composites were measured by freespace measurement system over X-band. Two single slab absorbers and a double slab absorber were designed by thickness optimization method. Single slab absorbers did not show good microwave absorption performance because the permittivity is away from non-reflection curve. Double slab absorber complemented the limitations on single slab absorber and it showed good microwave absorption performance. Double slab absorber showed -43.9 dB loss near 10 GHz.

• Journal of Biosystems Engineering
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• v.30 no.3 s.110
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• pp.147-154
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• 2005

The improved hitch device, which connecting the trailer to power tiller, was developed. This device, composed with spring and rubber, could reduce the vibration and shock levels during driven on off-road. The vertical vibration accelerations for the improved hitch device were measured at 6 positions, i.e. engine, hitch, seat, and three points in trailer (front, middle, and rear) for not driving but at low engine speed of 500 rpm, and compared with the existing hitch device. The results of this study could be summarized as follows; The average vibration acceleration up to 120 Hz was $0.4m/s^2$ at engine part, but it was 0.08 and $0.05m/s^2$ at trailer for existing and improved hitch device, respectively. About $38\%$ of average acceleration level could be absorbed for the improved hitch device compared with existing hitch device. The average vibration acceleration up to 40 Hz was reduced to 0.12 and $0.06m/s^2$ at trailer for existing and improved hitch device respectively, showing the reduction effect of $50\%$. The maximum acceleration occurred at up to 20 Hz of low frequency was much higher than total acceleration occurred at up to 120 Hz, which means that much loss or damage could be occurred during transporting of agricultural products on off-road. The portions of average acceleration occurred at up to 20 Hz of low frequency were $27\%\;and\;21\%$ for the existing and improved hitch device, respectively.

• Analytical Science and Technology
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• v.8 no.1
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• pp.9-16
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• 1995

The low concentration of cadmium in the whole-blood was determined by graphite furnace atomic absorption spectrometry(GFAAS) after the sample was diluted five-fold by 1% Triton X-100, 2% $(NH_4)_2HPO_4$ as matrix modifier and pyrocoated graphite tube with L'vov platform was tried remove the interferences of blood matrix and reduce the loss of volatility of cadmium at higher ashing temperature($600^{\circ}C$). The criteria for evaluating the accuracy and precision of this analysis was confirmed by analysis of interlaboratory comparison(Japan) and NIST SRM No. 909(Cd in Serum). The limit of the determination for cadium was 0.1ng/ml and the relative standard deviation(RSD) at 1.0ng/ml level was about 10% for the GFAAS.

• Journal of the Korean Wood Science and Technology
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• v.18 no.4
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• pp.53-64
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• 1990

This study was carried out to develop the traditional korean paper changphanji from the bast fiber of paper mulberry The results obtained were as follows: 1. The variations in the basis weight were remarkable, but there were no significant adverse effects on the tensile strength and thickness. 2. The stamping have contributed to the improvement of smoothness and the control of thickness. The automatic pressing system recommended to obtain good control of thickness. 3. The average density of the traditional korean paper changphanji was 1.06g/$cm^3$. 4. The changphanji developed in this study gave a clude, but excellent toughness and warm feeling. Some fiber lumps, dark spots and bamboo, screen marks were also obserded. 5. The tensile strength of four-fold sheet changphanji is highest and those of two-fold sheet changphanji is lowest. the lengthwise tensile strength was higher than crosswise one due to the fiber. 6. The elongation of three-fold sheet changphanji was highest 7. The water absorption of all products ranged from 11.3g/$m^2$ to 17.5g/$m^2$. 8. The wight loss by abrasion was 34.0%(four-fold sheet) 31.6%(three fold sheet), 31.0% (two-fold sheet)respectively. 9. Based on the results obtained. tensile strength and elongation, the four-fold sheet was excellent. the use of the bast fiber of paper mulberry as a raw material is attractive point which can not obtained from the commercial changphanji made from other raw materials.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.65-71
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• 2013

PURPOSES : The objective of this study is to evaluate the effect of physical characteristics of emulsion asphalt and aggregate on performance of chip seal pavements. METHODS : In order to evaluate the performance of chip seal materials, the sweep tests and Vialit Plate Shock tests were conducted on the mixtures with five emulsion asphalt binders and three aggregate types. The sweep tests was intended to investigate the change of bonding properties between emulsion asphalt and aggregate with curing time. The Vialit Plate Shock test was used to evaluate the bonding properties of chip seal materials at low temperatures. RESULTS : Results from sweep tests showed that polymer modified emulsion asphalt can reduce the curing time by 1.5 hour comparing with typical emulsion asphalt. It is also found that the Flakiness Index of aggregates and absorption rate of binder are the major factors affecting the bonding properties of chip seal materials. The Vialit Plate Shock test results showed that the average aggregate loss of CRS-2 is ten times higher than CRS-2P No.2 indicating that the use of polymer additives in emulsion asphalt can improve the performance of chip seal materials in low temperature region. CONCLUSIONS : The use of polymer in emulsion asphalt can decrease the curing time of chip seal materials and increase the bonding properties between aggregates and asphalt binder. It is also concluded that the lower Flakiness Index and absorption rate of aggregates can improve the performance of chip seal pavement.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.177-189
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• 2001

T hydrogen absorption-desorption behavior induced by thermal or hydrogen pressure cycling in a closed system was observed in hydrogen storage alloys, $(La-R-Mm)Ni_{4.5}Fe_{0.5}$, $MmNi_4Fe_{0.85}Cu_{0.15}$ and $(Ce-F-Mm)Ni_{4.7}Al_{0.2}Fe_{0.1}$. Thereby (La-R-Mm), Mm and (Ce-F-Mm) refer to La-rich mischmetal, mischmetal and Ce-free mischmetal respectively. As the results, it is found that the alloy stabilities during thermal cycling varies with alloy composition change. The highest stability occurs in $MmNi_4Fe_{0.85}Cu_{0.15}$ and the lowest stability in $(La-R-Mm)Ni_{4.5}Fe_{0.5}$. Comparing hydrogen pressure cycling with thermal cycling, pressure cycling causes severer degradation of the alloy $(Ce-F-Mm)Ni_{4.7}Al_{0.2}Fe_{0.1}$ than thermal cycling. When the 1500 times-cycled alloy is annealed at $400^{\circ}C$ for 3hrs under 1 atm of hydrogen pressure the hydrogen storage capacity is recovered only partially but not completely to the initial capacity. The amount of capacity loss after annealing is larger in the hydrogen pressure cycled samples than in the thermal cycled, suggesting an incoming of impure gas during hydrogen pressure cycling.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.795-799
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• 2004

Noodles were prepared by adding 25, 50, 75, and 100% wax gourd juice to wheat flour, and effects of added wax gourd juice on dough rheology and cooking and noodle qualities were examined. Initial pasting temperature, and peak and final viscosities increased with addition of wax gourd juice. Water absorption and dough weakness, and cooked weight, moisture absorption, cooked volume, and cooking loss of noodleincreased, but dough development time and dough stability decreased with increase in wax gourd juice content. Hardness, cohesiveness, and gumminess of cooked noodles increased significantly with increase in war gourd juice content. Sensory evaluation results reveal noodles containing 25 and 50% wax gourd juices have higher qualities than other types.

• Advances in concrete construction
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• v.4 no.2
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• pp.123-143
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• 2016

Use of heavy fuel fly ash (HFFA) (diesel and cracked fuel) for power generation in Saudi Arabia has generated and accumulated large quantities of HFFA as a byproduct. In this research, HFFA is studied with the emphasis on the utilization of this waste material in concrete blocks and asphalt concrete mixes. Two types of mixes, one with low and other with high cement content, were studied for concrete blocks. Different mixes having varying percentages of HFFA (0% to 25%), as cement/sand replacement or as an additive, were studied. The performance of concrete blocks is evaluated in terms of compressive strength, water absorption, durability and environmental concerns. The results showed that blocks cannot be cast if more than 15% HFFA is used; also there is a marginal reduction in the strength of all the mixes before and after being exposed to the sulfate solution for a period of ten months. HFFA is studied in asphalt concrete mixes in two ways, as an asphalt modifier (3&5%) and as a filler (50%) replacement, the results showed an improvement in stiffness and fatigue life of mixes. However, the stability and indirect tensile strength loss were found to be high as compared to the control mix due to moisture damage, indicating a need of using antistripping agents. On environmental concerns, it was found that most of the concerned elements are within acceptable limits also it is observed that lower concentration of barium is leached out with the higher HFFA concentrations, which indicates that HFFA may work as an adsorbent for this leaching element.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.287-296
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• 2010

This study was designed to investigate the influence of the pH and enantiomer on the antioxidant activity of Maillard reaction mixture solution in model systems. The loss of glucose in MRPs did not show different characteristics for the different amino acid enantiomers; however, the concentration of glucose decreased as the pH levels increased. The enolization of sugars was observed in all MRP samples according to increase of pH levels. In addition, D-amino acids were detected in L-amino acid systems and L-amino acids could also be observed in D-amino acid systems. Formation of the isomer was the highest in the Glc/L-Lys system. The browning development increased as pH levels increased; however, browning development did not show different characteristics based on the use of L- versus D-isomers of the same amino acid. The L- and D-isomers show different absorption values in the UV-Vis spectra, but the absorption patterns display a similar shape. The antioxidant activities of MRPs derived from the Glc/Gly, Glc/L-Asn and Glc/D-Asn systems at pH 7.0 were greater compared to those of pH 4.0 and pH 10.0. The antioxidant activities of MRPs derived from the Glc/L-Lys and Glc/D-Lys systems decreased as the pH increased. In addition, the results show that the MRPs derived from the D-isomers have similar antioxidant activities as those from L-isomer. Therefore, the MRPs have the different antioxidant activities on the basis of the pH level, but not on the basis of different amino acid enantiomers.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.145-149
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• 2011

Poly(butylenes terephthalate) have made large strides in applications of injection, extrusion, and molding material due to their excellent thermal resistance and appropriate mechanical properties. However, PBT was not hard polymer but a soft polymer which caused low absorption of external energy and the defect of being easily broken with the strong impact. Thus, the electron beam irradiation was carried out over a range of irradiation doses from 100 to 1,000 kGy for enhancing the properties. The decreases of $T_m$, $T_c$, and enthalpy were observed as increasing the absorbed dose in the results of DSC analysis. The improvement in the impact strength of PBT was clearly observed as the absorbed dose was increased. This was probably due to the 3-dimensional network structures, resulting in increasing the absorption of impact energy. In addition, the wear properties had increased at higher than 300 kGy. The negative deviation of weight loss confirmed the improvement of the wear properties of PBT, as evidenced by SEM observation on the wear surfaces.