• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.136-137
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• 2018

The properties of concrete produced by ready mixed concrete company in Busan were measured. Because the concrete was mixed with blast furnace slag and fly ash etc., the compressive, tensile strength and chloride ion diffusion coefficient were lower than OPC concrete even though the specified concrete strength was same. If the durability about salt attack were satisfied, the concrete of lower specified concrete strength would be adopted to concrete mixing design. FEM analysis was carried out to predict the life time expectancy.

• Journal of Power System Engineering
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• v.4 no.1
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• pp.39-44
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• 2000

The purpose of this study is to investigate the flame structure and combustion characteristics in the model gas turbine combustor changing equivalence ratio. For this purpose, temperature and ion current were measured and these data were analyzed by the PDF and power spectra technique. We found that the flame length is longer while increasing the equivalence ratio in experimental condition, and especially ${\psi}=0.19$, combustion reaction was active by the stable swirl flow. and these flames were governed by the random three dimensional eddy.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.426-431
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• 1996

It is well known that the understanding of the complex mechanism of magnetoplasma is closely related with understanding of the collective behavior of discharge plasma parameters such as the cathode-sheath potential, cathode-sheath thickness, electron temperature, electron density, and ambipolar diffusion. In this paper, some of the relationships between these plasma parameters and magnetic field is investigated experimentally with a Langmuir probe in the magnetoplasma generated by D.C diode system. It is found that when magnetic field is increased, cathode-sheath potential, cathode-sheath thickness, and ambipolar diffusion are decreased. In addition, peak ion density obtained as a parameter of ionic signal voltage by Faraday cup method is independent of magnetic field. (author). 9 refs., 11 figs.,1 tab.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.149-150
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• 2018

The RC buildings which are constructed on the seaside are followed by KBC(2016) to achieve the minimization of durability damage. To control the corrosion of the reinforced steel bar by salt attack, W/C should be under 0.4 and specified concrete strength is more than 35MPa in the concrete/building construction standard specification. Ready mixed concretes which have usually include the admixtures in Busan were tested to certify the salt attack durability. In the same specified concrete strength, remarkable salt attack durability was evaluated in comparison to OPC.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.146-152
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• 2018

Due to their excellent mechanical durability and high electrical conductivity, carbon and silicon composites are potentially suitable anode materials for Li-ion batteries with high capacity and long lifespan. Nevertheless, the limitations of the composites include their poor ionic diffusion at high current densities during cycling, which leads to low ultrafast performance. In the present study, seeking to improve the ionic diffusion using hydrothermal method, electrospinning, and carbonization, we demonstrate the unique design of excavated carbon and silicon composites (EC/Si). The outstanding energy storage performance of EC/Si electrode provides a discharge specific capacity, impressive rate performance, and ultrafast cycling stability.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.329-332
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• 1999

An automated method is developed for simultaneous determination of water soluble gases at parts per trillion level in the environmental air. The method involves temperature-humidity control of sample air using a thermostated humidifier, collection of analyte gases by condenser-type effluent diffusion denuder and subsequent effluent analysis by ion chromatography. The detection limits (3(σ) of the method for CH3COOH, HNO2 and SO2 gases are 0.022, 0.019 and 0.009 ppbv, respectively. The precisions range from 0.3 to 3.0% RSD. The method has been successfully applied to urban air analysis and some results for nitrous acid and SOx, in Seoul air are presented.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.90-94
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• 1995

Defects introduced by Si, Ge preamorphization and their effects on the dopant diffusion and electrical characteristics. Good crystalline quality are obtained after the annealing of Ge ion double implanted samples. The defect clusters under the a/c interface are expected to extend up to the deep in the Si ion implanted samples. The dislocation loops near the junction absorb the interstitial Si atoms resolving from the defect cluster and result in the prevention of enhanced boron diffusion near the tail region of boron profile and show good reverse current charactristics.

• Computers and Concrete
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• v.31 no.6
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• pp.485-499
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• 2023

Both damage and unsaturated conditions accelerate the transport of erosive media inside concrete. However, their combined effects have not been fully investigated. A multiscale mortar model using representative volume elements is developed, capturing the number and distribution in each phase. Afterwards, mortar damage microstructure evolution is simulated in the tensile process. Finally, the unsaturated mortar transport is predicted and analysed. The results indicate that damage significantly affects the diffusion process in the early stage, while the transport performance is weakened due to the obstruction of the nontransport phase in the later stage. The higher the saturation and the more connected pores, the faster the diffusion rate of chloride ions. Chloride ions spread around the cracks in a tree-like manner along. The model can very well predict the chloride ion transport performance of unsaturated and damaged mortar.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.735-742
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• 2005

The purpose of this study was to evaluate the salt water resistance of concrete depending on various types of cement. In this regard, 5 types of concrete were selected and their strength, void ratio and chloride ion diffusion characteristics were tested, and mutual correlation were analyzed. From the test results, the compressive strength and void ratio of concrete which using Type V cement was as good as Type I cement at long-term ages but the chloride diffusion coefficient of Type V cement was larger than Type I cement. And the concrete replacing some portion of the Type I cement with fly ash was superior in the cases of compressive strength, void ratio and the resistance of chloride ion permeation compared to the Type I cement with the lapse of ages. On the other hand, the compressive strength, the void ratio and the chloride diffusion coefficient of the concrete all indicated high levels of the correlation coefficient and the coefficient of determination regardless of the type of cement.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.349-359
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• 1992

Studies were carried out on the selective removal of inorganic salts such as NaCl and $Na_2SO_4$ from dye solution, using counter diffusion-reverse osmosis and nanofiltration, respectivey. For the dye solution used in the experiments, 1 to 30% of salts were removed by counter diffusion while the loss of dye molecules was less than 0.3%. The separation factors by one pass operation were 10-500 according to ionic species. In five successive operations, removals of anion($Cl^-$) increased but those of cation($Na^+$) decreased due to the Donnan effect. Effects of feed flow rate on removal efficiencies of various ions were also observed at constant flow rate of stripping water. Reverse osmosis of desalted dye solution by counter diffusion was conducted to prepare highly concentrated liquid dyes. The rejection efficiency of dye molecules was greater than 99%. For the rejection efficiency of chloride ion, experimental values were compared with theoretical ones based on solution-diffusion model. Two stage diafiltration was performed in nanofiltration. The rejection efficiency of chloride ion was continuously decreased due to the Donnan dialysis and even negative rejection was observed. The Donnan effect was more pronounced in the second diafiltration.