• Progress in Superconductivity
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• v.1 no.1
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• pp.9-13
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• 1999

The influence of quenching temperature and annealing time on superconducting characteristics has been investigated for a $(Pb_{0.6}V_{0.4})Sr_2(Ca_{0.65}Er_{0.35})Cu_2O_z$ compound. From the resistivity measurements for samples annealed at $400^{\circ}C$ to $860^{\circ}C$ in oxygen and subsequently quenched, it is observed that $T_c$(zero) of the sample decreases with the increase of annealing temperature up to $600^{\circ}C$ and increases again beyond $700^{\circ}C$. Annealings of the sample at $860^{\circ}C$ show that $T_c$(zero) goes through a maximum of 62K with the increase of the annealing time. It is also found that $T_c$(zero) of the sample quenched from high temperature decreases when the sample is subjected to low temperature annealing below. $600^{\circ}C$ in oxygen. The experimental results indicate that the as-prepared samples contain excessive oxygen and removal of this excessive oxygen in as-prepared samples is a key factor in controlling the superconducting properties of the samples and are discussed in connection with thermal gravimetric measurements.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.21-27
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• 2013

The lowest values of the AITs(Autoignition temperatures) in the literature were normally used fire and explosion protection. In this study, the AITs of n-Propanol+n-Octane system were measured from ignition delay time(time lag) by using ASTM E659 apparatus. The AITs of n-Propanol and n-Octane which constituted binary systems were $435^{\circ}C$ and $218^{\circ}C$, respectively. The experimental ignition delay time of n-Propanol+n-Octane system were a good agreement with the calculated ignition delay time by the proposed equations with a few A.A.D.(average absolute deviation).

• Journal of the Korean Society of Food Culture
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• v.11 no.3
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• pp.385-392
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• 1996

The soluble solid of red pepper was extracted by water in order to investigate changes of soluble solid content by different extraction temperature $(4{\sim}90^{\circ}C)$ and time $(1/2{\sim}3\;hrs)$, and the contents of carotenoid, capsaicinoids, free sugar, organic acid, free amino acid in soluble solid were measured. Most of soluble solid in red pepper was extracted within the first 2 hrs and $93{\sim}98%$ of total soluble solid was extracted during the first 30 min. The contents of carotenoid increased by increasing extraction time and temperature, but decreased by increasing extraction time at $60^{\circ}C$ and $90^{\circ}C$. ${\beta}$-carotene content was sharply decreased after 2 hrs at $90^{\circ}C$. The content of capsaicinoid was sharply increased between 1 hr and 2 hr. Fructose and glucose in red pepper were extracted in the range of $83.8%{\sim}96.4%$ and the contents of free sugar gradually increased by increasing extraction time and temperature. The content of organic acid was gradually increased by increasing extraction time and temperature and the greatest amount of organic acid was extracted during the first 30 min of extraction time. The content of free amino acid was decreased by increasing extraction temperature.

• Journal of Powder Materials
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• v.26 no.6
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• pp.493-501
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• 2019

In this work, ultra-fine calcium oxide (CaO) powder derived from eggshells is used as the starting material to synthesize mineral trioxide aggregate (MTA). The prepared CaO powder is confirmed to have an average particle size of 500 nm. MTAs are synthesized with three types of fine CaO-based powders, namely, tricalcium silicate (C3S), dicalcium silicate (C2S), and tricalcium aluminate (C3A). The synthesis behavior of C3S, C2S and C3A with ultra-fine CaO powder and the effects of C₃A content and curing time on the properties of MTA are investigated. The characteristics of the synthesized MTA powders are examined by X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), and a universal testing machine (UTM). The microstructure and compressive strength characteristics of the synthesized MTA powders are strongly dependent on the C3A wt.% and curing time. Furthermore, MTA with 5 wt.% C3A is found to increase the compressive strength and shorten the curing time.

• Journal of Life Science
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• v.10 no.2
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• pp.202-209
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• 2000

The factors affecting chemical composition of green tea (Camellia sinensis L.) during extraction process were temperatures and times. The optimum extraction conditions were measured in relation to the changes of chemical compositions from water extracts of green tea (Camellia sinensis L.) under different extraction temperatures (50, 70, 9$0^{\circ}C$) and extraction times (1, 3, 5 minute). The change of color intensity during browning reaction, flavonoid components, contents of total phenols and hydrogen donating activity (reducing activity for $\alpha$, $\alpha$'-diphenyl-$\beta$ -picryhydrazyl) of water extracts form green tea increased as extraction temperatures increased from 50 to 9$0^{\circ}C$ and extraction times prolonged from 1 to 5 min. The contents of important free sugars such as sucrose and glucose slightly increased as the extraction time was prolonged, while little difference in the content of fructose with the prolonged extraction time. Catechins contents extracted from the commercial steamed green tea were increased at higher temperature and longer extraction time. Epigallocatechin (EGC) extracted from 9$0^{\circ}C$ (extraction time 5 min). presented 99.9 mg/g in highest composition of catechin followed by epigallocatechin gallate (EGCg), epicatechin (EC), epicatechin gallate (ECg). The content of vitamin C extracted from green tea was increased about 2 times as the extraction temperature increased from 50 to 9$0^{\circ}C$ and as the extraction time increased from 1 to 5 min. with exception at 9$0^{\circ}C$(extraction time:5 min) which showed less vitamin C content than 7$0^{\circ}C$(extraction time : 3 min) probably due to possible destruction of vitamin C by high temperature.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.4
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• pp.201-210
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• 2009

Cast fishing gear needs some time for fishing progress, and catches and their composition by submerged time can change by several cause. Therefore, it is very importance to study fishing capacity of fishing gear by submerged time. This study is to investigate catches and their composition of shrimp trap, that is used in the coastal of the East Sea, and to find the fittest lifting time of trap. Experimental term are September 2006 and August 2007, the location is the coastal of Oho, Goseong, Gangwondo, Korea and one hundred trap is used at each casting and lifting of gear. For convenience of description, survey of 2006 and 2007 are dented as experimental code 1 and 2, and submerged time 21hr, 43hr and 66hr are dented as code A, B and C. The result of obtained from the above approach are summarized as follows: Many Northern shrimps(Pandalus eous), dominated 96.36%, are only catched in experimental code A, and in code B and C, some of coonstripe shrimp(Pandalus hypsinotus) and few morotoge shrimp(Pandalopsis japonica) are catched. CPUE of code 1A, 1B and 1C per trap were 21.67g, 29.51g and 28.48g, and those of code 2A, 2B and 2C per trap were 25.44g, 32.93g and 33.36g. Therefore, 24.66% of catch increased according as submerged time passes from 1 day to 2 days, and almost no change of catch was to be -1.1%. Carapace length of code 1A, 1B and 1C were 23.77mm, 25.00mm and 25.57mm, and those of code 2A, 2B and 2C per trap were 23.83mm, 24.95mm and 25.45mm. Thus, the more submerged time is, the less catch of small fish is and the more catch of large fish is. Consequently, fit lifting time of shrimp trap is after 2 days, and if considered trouble of fishing gear and condition of catch, the fittest lifting time is the third successive day of casting date.

• Structural Engineering and Mechanics
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• v.43 no.3
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• pp.311-320
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• 2012

The higher-order asymptotic C(t) - $A_2(t)$ approach was employed to investigate the crack-tip stress of two collinear cracks in a power-law creeping material under the plane strain conditions. A comprehensive calculation was made of the single crack, collinear crack model with S/a = 0.4 and 0.8, by using the C(t) - $A_2(t)$ approach, HRR-type field and the finite element analysis; the latter two methods were used to check the constraint significance and the calculation accuracy of the C(t) - $A_2(t)$ approach, respectively. With increasing the creep time, the constraint $A_2$ was exponentially increased in the small-scale creep stage, while no discernible dependency of the constraint $A_2$ on the creep time was found at the extensive creep state. In addition, the creep time and the mechanical loads have no distinct influence on accuracy of the results obtained from the higher-order asymptotic C(t) - $A_2(t)$ approach. In comparison with the HRR-type field, the higher-order asymptotic C(t) - $A_2(t)$ solution matches well with the finite element results for the collinear crack model.

• Journal of Powder Materials
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• v.6 no.2
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• pp.178-185
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• 1999

MoSi$_2$-TiC composite powders were fabricated by in-situ reaction through mechanical alloying. Also the monolithic MoSi$_2$ as well as TiC were synthesiced by mechanical alloying for comparison. An abrupt increase of vial surface temperature was detected due to a sudden reaction between elemental powders during milling. The reaction time for synthesis of composite powders decreased with increasing the content of (Ti+C) powder. It was found that a significant decrease of Ti grain size was observed with increasing the milling time. And the synthesis reaction of MoSi$_2$-TiC composite powders were largely dependent on the reaction between Ti and C powders.

• Journal of environmental and Sanitary engineering
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• v.18 no.2
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• pp.1-8
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• 2003

The advantages of hydrogen peroxide dissolution method were no discharge of noxious matter when dissolution of molybdenum wire which used as the center supporter, reactions occur in room temperature. The results were as follows : 1. In the FL/10-A type: Dissolution-reaction Time was 50Min., C.R.(Coil resistance) was $9.27{\Omega}(St.{\;}:{\;}9.2{\pm}0.22{\Omega})$, P.W.(Piece weight) was $10.59mg(St.{\;}:{\;}10.5{\pm}0.26mg)$. In the FL/15-D type: Dissolution-reaction Time was 55Min., C.R. was $6.39{\Omega}(St.{\;}:{\;}6.38{\pm}0.02{\Omega})$, P.W. was $16.7mg(St.{\;}:{\;}16.5{\pm}0.3mg)$. In the FL/20-H type: Dissolution-reaction Time was 45Min., C.R. was $4.7{\Omega}(St.{\;}:{\;}4.6{\pm}0.3{\Omega})$, P.W. was $20.8mg(St.{\;}:{\;}20{\pm}1.5mg)$. In the FL/20-C type: Dissolution-reaction Time was 60Min., C.R. was $4.5{\Omega}(St.{\;}:{\;}4.6{\pm}0.3{\Omega})$, P.W. was $19.8mg(St.{\;}:{\;}19{\pm}1.0mg)$. 2. In the GLS-230/40-B type: Dissolutiona-reaction Time was 45Min., C.R. was $105.1{\Omega}(St.{\;}:{\;}104{\pm}2.6{\Omega})$, P.W was $6.37mg(St.{\;}:{\;}6.3{\pm}0.16mg)$. In the GLS-230/60-F type: Dissolution- reaction Time was 45Min., C.R. was $65.92{\Omega}(St.{\;}:{\;}65{\pm}1.62{\Omega})$, P.W. was $11.91mg(St.{\;}:{\;}11.8{\pm}0.29mg)$.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.90-98
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• 2002

In this paper, the annealing heat treatments for the best corrosion resistant of Ti(Grade 2) were studied in a 3.5% NaCl solution by electrochemical methods. The annealing heat treatments were accomplished at 650, 700 and $750^{\circ}C$ with different time of 30min., 1hour and 2 hours in a vacuum condition. The obtained results are: 1) in the case of solution heat treated $930^{\circ}C$ for 2 hours in a vacuum and air, the corrosion potentials were -348.7 and -567. 1mV, and current densities 2.32 and $22.62\mu\textrm{A}$, respectively, 2) as increase both annealing heat treatment temperature 650, 700, $750^{\circ}C$ and time 30min., 1 hour, 2 hours, the corrosion potential were decreased, whereas corrosion current density increased, 3) in the case of cyclic polarization, the measured charges were increased as increasing solution heat treatment temperature and time, 4) on the bases of corrosion potential, current density and charge, the best annealing temperature and time were measured as $700^{\circ}C$ and 30min. for Ti(Grade 2) material.