• Korean Journal of Materials Research
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• v.27 no.10
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• pp.524-529
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• 2017

The effect of strain aging on the tensile properties of API X70 linepipe steel was investigated in this study. The API X70 linepipe steel was fabricated by controlled rolling and accelerated cooling processes, and the microstructure was analyzed using optical and scanning electron microscopes and electron backscatter diffraction. Strain aging tests consisting of 1 % pre-strain and thermal aging at $200^{\circ}C$ and $250^{\circ}C$ were conducted to simulate U-forming, O-forming, Expansion(UOE) pipe forming and anti-corrosion coating processes. The API X70 linepipe steel was composed of polygonal ferrite, acicular ferrite, granular bainite, and bainitic ferrite whose volume fraction was dependent on the chemical composition and process conditions. As the thermal aging temperature increased, the steel specimens showed more clearly discontinuous type yielding behavior in the tensile stress-strain curve due to the formation of a Cottrell atmosphere. After pre-strain and thermal aging, the yield and tensile strengths increased and the yield-to-tensile strength ratio decreased because yielding and aging behaviors significantly affected work hardening. On the other hand, uniform and total elongations decreased after pre-strain and thermal aging since dislocation gliding was restricted by increased dislocation density after a 1 % pre-strain.

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.77-79
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• 2004

It is caused that insulation paper, which had got a lot of thermal stress by over-load after installation, should have been deteriorated in electrical and mechanical characteristics. Beside, insulation material is decreased the insulating property and accelerated aging of them in case of dielectric loss when transformers are manufactured with some moisture or transformers would have been them because of moisture-permeation. Therefore, in this study we experienced the influence of moisture content in case of the thermal aged insulation paper. we have measured tan 6 and breakdown voltage in the ratio of paper' moisture content before the aging and then taken the same tests again after insulation paper thermally accelerating-aged. There is a purpose to gain data for a life-design and to establish aging mechanism in order to continuously study life expectancy of the insulation paper

• Clean Technology
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• v.12 no.2
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• pp.101-106
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• 2006

HT-$LiCoO_2$ powders were synthesized from hydroxide precursors in this study. The cobalt hydroxide compounds with hydrotalcite-like(${\alpha}$-phase) and/or brucite-like(${\beta}$-phase) structures as a component of the precursor were prepared in various PH conditions using precipitation method. It was found that various phase and compositions of cobalt hydroxides could be tailor-prepared via a careful control of preparation parameters such as the concentration ratio of $[OH^-]/[CO^{2+}]$ and aging time. The hydroxides $Co(OH)_2$ and LiOH were mixed with aqueous methyl-alcohol. The precursor of a HT-$LiCoO_2$ was synthesized via subsequent processes including evaporation, drying and aging. The transformation of tailor-made ${\beta}$-phase $Co(OH)_2$ to CoOOH and formation of solid solution in the precursor were achieved during aging. These results cause HT-$LiCoO_2$ to be synthesized at low temperature($600^{\circ}C$ ) for a short time(10min).

• Elastomers and Composites
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• v.6 no.1
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• pp.53-70
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• 1971

We have studied the blending effects of cis-1,4-polybutadiene (CBR) and styrene-tutadiene rubber at various blending ratios of 100 : 0, 70 30, 50 : 50, 30 : 70, 0 : 100, and of carbon black ISAF and HAP at various compounding ratios of 45 PHR, 55 PHR, 65 PHR, for tyre tread rubber. The results obtained are summerized as follows; 1. For tyre tread rubber, it was found to increased efficiency to use SBR polymer only than to use the blending ratio CB/SBR=30/70 below. But it was observed that the latter was adapted for the bus or truck tyre and the former for the passenger tyre. 2. Excellent efficiency was obtained in case of carbon black compounding ratio of 55%, and also the compounding of ISAF made better efficiency than that of HAF. 3. Carbon black was more efficient to SBR than to CB. 4. For the aging ratio, the compounding rubber of NR was the highest, and the ratio was decreased in order of the compounding rubber of oil-extended SBR or CB polymer only, the compounding rubber of non oil-extended SBR or CB polymer only, and the blending rubber.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.647-653
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• 1997

To establish the index of aging stage for cold storage beef tenderloin, shear force value(SFV), Mg-ATPase activity, myofibrillar fragmentation index(MFI), myofibrillar fragmentation ratio(MFR) and appearance of 30KD(30KD) were measured as the parameters for the indices of aging stage. Aging index of air-packed beef tenderloin stored for 14 days at 3$^{\circ}C$ were useful in the order of SFV(r=-0.893)>MFR (r=0.863) >30KD(r=0.853)>MFI(r=0.814)>Mg-ATPase activity(г=0.804). Vacuum-packed beef tenderloin stored for 28 days at 3$^{\circ}C$ were useful in the order of MFR(r=0.880)>30KD(r=0.836). In case of the correlation between aging indices of air-packed beef tenderloin, MFR had relation with SFV, Mg-ATPase activity, MFI and 30KD. In case of the correlation between aging indices of vacuum-packed beef ten- derloin, MFR had relations with 30KD.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.581-587
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• 2012

Thermal aging effect on NSR kinetics was studied over Pt/Co/Fe/Ba/$Al_2O_3$ catalyst. The amount of $NO_x$ uptake over Pt/Co/Fe/Ba/$Al_2O_3$ calcined at $400^{\circ}C$ increased with increasing NSR temperature from $200^{\circ}C$ to $400^{\circ}C$, where amount of $NO_x$ uptake is the highest at $400^{\circ}C$ with mol ratio of $NO_x$/Ba = 0.5. Thereafter, the amount of $NO_x$ uptake at $400^{\circ}C$ decreased with the higher calcination temperature, where Pt/Co/Fe/Ba/$Al_2O_3$ catalyst calcined at $700^{\circ}C$ showed an amount of $NO_x$ uptake with the mol ratio of $NO_x$/Ba=0.062. Result of XRD and NSR showed that Fe addition into Pt/Co/Fe/Ba/$Al_2O_3$ suppressed sintering of Pt crystallites and make $NO_x$ uptake larger, compared to no addition of Fe into Pt/Co/Fe/Ba/$Al_2O_3$ catalyst. From BET result, it was found that the change of specific surface area was relatively small by the thermal aging process. Therefore, it was found that the sintering of Pt crystallites caused the decrease of $NO_x$ uptake during NSR reaction and Fe played a role to suppress the sintering process of Pt crystallites caused by thermal aging.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.2
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• pp.125-132
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• 2003

Uzi fly (Exorista bombycis Louis) is one of the major larval endo-parasitoid of silkworm (Bombyx mori). It causes extensive damage to sericulture industry. The application of synthetic organic pesticides has tremendous impact on minimizing pest population but their overuse and frequent misuse and high sensitivity towards the silkworms, has forced the entomologists to search for alternatives to chemical control, which is safe to silkworm, environment and farm workers. Biological control continues to offer exciting possibilities for the control of fly pest population. It is environmentally safe alternative to chemical control and offering a long-term protection. Several potential hymenopteran parasitoids have been screened. Among successful natural enemies, Nesolynx thymus, Trichomalopsis apanteloctena, Trichopria sp., Brachymeria lasus, Pediobius sp., Spalangia sp., Spilomicrus karnatakensis and Dhirhinus sp. are important. It is essential to predict accurately the efficacy of these natural enemies in a new habitat prior to its introduction. The important desirable attributes of these potential parasitoids viz., host searching capacity, specificity, power of increase and fitness and adaptability of the parasitoid in new environment has been recorded. Results of the host parasitoid interaction indicate that the aging of the host function as a factor that influence the host finding efficiency of the parasitoid. It is highly scored with 15-20 hrs old pupa of the host. However, aging of the parasitoid does not significantly affect it. The sex ratio is female biased which is advantageous from biological control point of view, Biological suppression methods involving conservation and utilization of natural enemies have been discussed in detail.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.422-429
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• 1992

The morphology and adhesion properties of rubber compounds containing resorcinol formaldehyde(RF) resin and hexamethoxymethylmelamine(HMMM) used in adhesion of rubber to brass-plated steel cord was investigated. The resins were spherical particles about $2000{\AA}$ diameter and distributed in rubber compounds homogeneously, and the cured compound with steel cord showed migration of resin to steel cord. Also, modulus was increased with increasing HMMM contents. The loss of adhesion between rubber and steel cord was likely to be at initial stages by thermal aging. Considering the physical properties, suability of adhesion layer and thermal aging property, optimum ratio of RF resin and HMMM was 1 : 0.9.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2004.12a
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• pp.1-16
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• 2004

This study was conducted to investigate effects of different ratios of sawdust to poultry manure as an earthworm feed on the change of physico-chemical characteristics and earthworm viability during composting, and further to provide the basic information for an efficient vermicomposting using the manure of livestock. Experimental earthworm used in this study was Eisenia foetida and the ratio of sawdust and poultry was determined to 100:0(A), 80:20(B), 70:30(C), 60:40(D) and 50:50(E) on the basis of volume. The results are summarized as follows. Earthworm appeared after 6 wk of aging period, and it was possible for the earthworm to survive in treatments of C. D and E including 30 $^{\sim}$ 50% of sawdust. C/N ratio was significantly higher (P<0.05) in treatments of sawdust mixture (B, C, D, and E) than poultry manure alone (A treatment).Appropriate C/N ratio for earthworm survival was the range of 16.9 to20.7. During period of aging, pH value and electrolyticconductivity (EC) were the highest in the treatment of poultry manure alone. However, as the inclusion of sawdust was increased, pH showed decreasing tendency. Appropriate pH and EC for earthworm survival were 7.69 to 7.79, and 2.77 to 2.87mS/cm, respectively. The results from this study indicated that the mixing of poultry manure with sawdust more improved physico-chemical environment for earthworm growth in comparison with poultry manure alone, and sawdust showed the sufficient possibilityas a bulking agent for an efficient vermicomposting of poultry manure.

• Korean Journal of Organic Agriculture
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• v.15 no.4
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• pp.425-435
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• 2007

This study was conducted to investigate the effect of different ratios of rice straw to swine manure as an earthworm feed on the change of physico-chemical characteristics and earthworm viability during composting, and further to provide the basic information for an efficient vermicomposting using the manure of livestock. Experimental earthworm used in this study was Eisenia foetida and the ratio of swine manure and rice straw was determined to 100:0(SM), 90:10(SRS 10), 80:20(SRS20), 70:30(SRS30) and 60:40(SRS40) on the basis of volume. The results are summarized as follows. Earthworm appeared after 8 week of aging period, and it was possible for the earthworm to survive in all the treatments. C/N ratio was significantly higher (P<0.05) in the treatments of rice straw mixture (SRS30 and SRS40) than swine manure alone (SM treatment). Appropriate C/N ratio for earthworm survival was the range of 10.43 to 11.16. During the period of aging, pH value and electrolytic conductivity (EC) were the highest in the treatment of swine manure alone. However, as the inclusion of rice straw was increased, pH value and EC showed a decreasing tendency. Appropriate pH value and EC for earthworm survival were 7.7 to 7.8, and 2.72 to 4.59mS/cm, respectively. The results from this study indicated that mixing swine manure with rice straw more improved more physico-chemical environment for earthworm growth in comparison with swine manure alone, and rice straw showed the sufficient possibility as a bulking agent for an efficient vermicomposting of swine manure.