• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.2
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• pp.80-86
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• 1995

High salinity common in reclaimed soil can reduce germination of crop seeds and aftermath its establishment and production. The experiment was done to measure germination and radicle elongation of berseem, subterranean, white clover and Italian ryegrass as Control under different temperature and NaCl concentrations. Onehundred seeds of berseem (Trifolium ulexandrinum cv. Bigbee). suberranean (T. suhterruneum, cv. Nungarin), white clover (T. repens, cv. Regal) and Italian ryegrass (Lolium mulriflorum, cv. Terafloum) were placed in petri dishes with a sheet of filter paper replaced every two days, and then exposed to 0, 12.5, 25. 50, 100 and 200mh4 of sodium chloride in darkened growth chambers controlled with 10, 15 and $20^{\circ}C$. Percent germination and radicle elongation were measured. Beneem clover showed greatest daily percent germination among the cloven. That of subterranean clover, moreover, was higher than that of white clover till 4 days after imbibition but the reverse result was true thereafter. Although germination of Italian ryegrass was delayed with decreased at 200mM of NaCl of $20^{\circ}C$. at 200mM of under$15^{\circ}C$ , and at higher than lOOmh4 of all level of temperature, respectively. Berseem clover had greatest radicle length under the same concentration of NaCl regardless of temperature treatment while radicle elongation of subterranean and white clover was repressed over 50-100mM of NaC1. The slope of linear regression equation between concentration of NaCl and percent germination declined under all temperature treatment in order of berseem, subterranean and white clover whereas the reverse result was showed in radicle length.

• Corrosion Science and Technology
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• v.18 no.4
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• pp.129-137
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• 2019

CFRP (Carbon Fiber Reinforced Plastics) is composed of carbon fiber and plastic resin, and is approximately 20 - 50% lighter than metallic materials. CFRP has a low density, higher specific stiffness, specific strength, and high corrosion resistance. Because of these excellent properties, which meet various regulation conditions needed in the industrial fields, CFRP has been widely used in many industries including aviation and ship building. However, CFRP reveals water absorption in water immersion or high humidity environments, and water absorption occurs in an epoxy not carbon fiber, and can be facilitated by higher temperature. Since these properties can induce volume expansion inside CFRP and change the internal stress state and degrade the chemical bond between the fiber and the matrix, the mechanical properties including bond strength may be lowered. This study focused on the effects of NaCl concentration (0.01 - 1% NaCl) and solution temperature ($30-75^{\circ}C$) on the galvanic corrosion between CFRP and A516Gr.55 carbon steel. When NaCl concentration increases 10 times, corrosion rate of a specimen was not affected, but that of galvanic coupled carbon steel increased by 46.9% average. However, when solution temperature increases $10^{\circ}C$, average corrosion rate increased approximately 22%, regardless of single or galvanic coupled specimen.

• KSBB Journal
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• v.10 no.4
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• pp.386-392
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• 1995

The high viscous ${\gamma}$-polyglutamic acid(${\gamma}$-PGA) from alkalophilic Alcaligenes sp. was purified and its solution property was investigated. The intrinsic viscosities for Na+ form and H+ form of ${\gamma}$-PGA were 31.1 and 0.38d$\ell$/g, respectively. The viscosity of H+-PGA was not influenced by pH or salts while that of Na+-PGA was influenced. The intrinsic viscosity of Na+-PGA solution decreased remarkably at the alkaline or acidic pH and showed the sharp decrease when salts were added. ${\gamma}$-PGA exhibited the property of the polyelectrolyte showing the .sharp decrease of intrinsic viscosity by the addition of NaCl, and intrinsic viscosity of dilute solution with the low concentration of NaCl was exponentially dependent on temperature and its temperature dependency increased with increasing NaCl concentration. The chain stiffness, coil overlap parameter and critical concentration of Na+-PGA were 0.08, 5.25 and 0.07g/d$\ell$, respectively.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1301-1307
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• 1995

Pitting corrosion of TiN film deposited on Inconel 600 by plasma assisted chemical vapor deposition (PACVD) was investigated. Cyclic potentiodynamic polarization (CPP) tests were conducted in order to determine the pit nucleation potentials, Enp, of the TiN-deposited sample and the bare Inconel 600 in deaerated NaCl solution at 25, 135 and 20$0^{\circ}C$. The effects of the TiN film thickness, the solution temperature and the Cl- concentration on Enp were studied. Enp of the TiN-deposited sample which had the film thickness above 1${\mu}{\textrm}{m}$ were higher than those of the bare Inconel 600 by 300~600mV at all the solution temperatures, implying the pitting resistance improvement of the TiN film. The morphologies of the pits generated after immersion test were examined with a scaning electron microscopy. The higher was the solution temperature, the more corrosion products, mainly composed of Cr and Ni oxides, were formed.

• Journal of the Korean Applied Science and Technology
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• v.27 no.4
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• pp.552-558
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• 2010

Zinc soap and Zn/Ba mixed metal soap were synthesized and PVC plastisol with mixed metal soap and various costabilizers were also synthesized with good structures and characterized by IR and $^1H$-NMR. The IR spectrums and $^1H$-NMR spectrums of the synthesized soaps were in very good accordance with the structures proposed by earlier workers. In using phosphite as a costabilizer, TIDP phosphite was shown to be the excellent thermal stabilization effect at the low temperature and TNPP phosphite was shown to be the excellent thermal stabilization effect at the high temperature. In case of antioxidant, it was revealed that antioxidant was not effective in the low temperature thermal stabilization effect while highly effective in the high temperature thermal stability. $NaClO_4$ solution with sorbitol solvent had the best thermal stabilization effect among $NaClO_4$ solution series at low and high temperature.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.33-40
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• 2023

Todorokite is a manganese oxide mineral containing Mg²⁺ in a tunnel structure in which MnO₆ octahedra share corners. In order to investigate the suitability and efficiency of high temperature-treated todorokite as a material for adsorption and fixation of Cs, Cs was ion exchanged and the amount of leached Cs from todorokite was measured. The todorokite used in this study was synthesized by transforming Na-birnessite to Mg-buserite and used as a precursor. After high temperature treatment, Cs exchanged todorokite changed to birnessite and hausmannite as the temperature increased. The amount of leached Cs was investigated for Cs exchanged todorokite which was reacted with distilled water and 1 M NaCl solution at different reaction times. In general, for the samples reacted with 1 M NaCl solution, the fixation of Cs was quite effective, although the amount of leached Cs was greater due to the ion exchange reaction with Na. As the treatment temperature increased, the amount of leached Cs increased and then decreased again, which was related to the mineral phases formed at each temperature. As birnessite was formed, the amount of leached Cs increased, but as birnessite decreased, that decreased again. As the mineral phase changed to hausemanite, the amount of Cs decreased rapidly. The results of our study show that Cs exchanged todorokite can be used as a material that effectively fixes Cs and prevents its diffusion by high temperature treatment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.399-406
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• 1990

This paper is studied to know corrosive wear mechanism of STS304 steel on atmospherical temperature against mating material as the same. The corrosive test was carried out by rubbing the annular surface of two test pieces in distilled water and NaCl aqueous solution. The corrosive wear mechanism was investigated by S.E.M. The experimental results show that there is one Lcr transferring from severe wear to mild wear on change of NaCl concentration and atmospherical temperature, and which is the other still remaining in server wear state. It was found that the critical sliding distance Lcr shorten with increasing NaCl concentration but it is longer with ascending atmospherical temperature and the mild wear state still continues under the condition of high generation rate and elimination rate of the corrosive product. Considering upon the result, the model of corrosive wear mechanism is proposed.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.152-156
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• 2007

Tungsten carbide powder was synthesized by SHS (self-propagating high-temperature synthesis). Except $WO_{3}$, each concentration of raw material ($WO_{3},\;Mg,\;NaCl,\;Na_{2}CO_{3},\;C$) was investigated. Final product was characterized by XRD and SEM. X-ray data demonstrated that the $NaCl+Na_{2}CO_{3}$ combined mixture has superiority in the WC formation process. Single phase and submicrometer WC powder was synthesized at the temperature below $1600^{\circ}C$. The role of sodium salts in combustion process was discussed, and chemical mechanism of WC formation was proposed. WC powder prepared by salt-assisted combustion synthesis has a size $0.2{\sim}3\;{\mu}m$ and low agglomeration degree.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.338-343
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• 2009

The purpose of this study is to make the tantalum powder for solid electrolyte capacitor with SHS (self-propagating high-temperature synthesis) process. Raw materials for manufacturing Ta powder were used $Ta_{2}O_{5}$, Mg and NaCl. While progressing SHS process, $Ta_{2}O_{5}$ powder was reduced by Mg powder. The combustion temperature and velocity were easily controled by the varying mole ratio of NaCl, Mg and initial reaction pressure. In the case of only using NaCl as an inorganic agent, the shape is unagglomerated and has high surface area. whereas we were given the powder which has good net structure by the addition of excessive Mg as a diluent.

• Corrosion Science and Technology
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• v.12 no.5
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• pp.220-226
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• 2013

The uncertainty in statistical noise resistance measurement was evaluated for a type 316 stainless steel in NaCl solutions at room temperature. Sensitivity coefficients were determined for measurands or variables such as NaCl concentration, pH, solution temperature, surface roughness, inert gas flow rate and bias potential amplitude. The coefficients were larger for the variables such as NaCl concentration, pH, inert gas flow rate and solution temperature, and they were the major factors increasing the combined standard uncertainty of noise resistance. However, the contribution to the uncertainty in noise resistance measurement from the above variables was remarkably low compared to that from repeated measurements of noise resistance, and thus, it is difficult to lower the uncertainty in noise resistance measurement significantly by lowering the uncertainties related with NaCl concentration, pH, inert gas flow rate and solution temperature. In addition, the uncertainty in noise resistance measurement was high amounting to 17.3 % of the mean, indicating that the reliability in measurement of noise resistance is low.