• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.299-304
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• 2002

This research was to investigate the invasion and diffusion properties of chloride ion on the concrete containing mineral admixtures by the electrically accelerated test. Mineral admixtures selected in mixes were fly-ash, ground granulated blast-furnace slag, silica fume, and meta-kaolin with 3 degrees of replacement ratios. Tang and Nilsson's test method was used to estimate chloride diffusion coefficients of that mixes. As a result, the total current passing charge and the diffusion coefficient of chloride ion were reduced with the use of mineral admixtures and the increase of replacement ratios. In addition, compressive strength was related with diffusion coefficient of chloride ion. Diffusion coefficients of concrete mixed with ground granulated blast-furnace slag showed relatively low value under the range of compressive strength of 400㎏f/㎠.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.271-279
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• 1987

A nitrate ion-selective PVC membrane electrode based on ammonia modified bakelite A-Ni$(NO_3)_2$ complex as ion exchanger was prepared. The electrode gave a linear response with a Nernstian slope of 60mV per decade within the concentration range $1{\sim}10^{-4}$ M $KNO_3$ but nonresponse to hydrogen ion and multivalent anions. The selectivity, response time and life time of the electrode were investigated and it was found that the electrode exhibited good selectivity for four univalent anions ($Cl^-,\;Br^-,\;I^-,\;{ClO_4}^-$). Analytical application to the determination of nitrate were also studied.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.7-12
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• 1986

Dielectric properties of $Ba_{0.9}Ca_{0.1}(Ti_{1-x}Sn_x)O_3$ were investigated from x=0 to 0.20, and temperature range -4$0^{\circ}C$~13$0^{\circ}C$ Density and grain size decreased with increasing Sn content due to grain growth inhibitor. Dielectric constant below the Curie temperature increased with increasing Sn content and dissipation factor dec reased. These results are due to grain size effect and internal stress. Curie temperature was shifted to lower temperature with increasing ratio of total polarizability to volume resulting from substitution of $Ba^{2+}$ ion with $Ca^{2+}$ ion $Ti^{4+}$ ion with $Sn^{4+}$ ion.

• Journal of Microbiology
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• v.34 no.1
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• pp.49-53
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• 1996

The effects of K$^{+}$ ion on the activity of RNA splicing of T4 phage thymidylate synthase gene have been investigated. The splicing activity was stimulated within the range of 5 to 20 mM concentration of KCI. When the concentration of KCI in the splicing reaction was brought to 100 or 200 mM a small amount of the exonl-intron product (1, 4 kb) was formed with large proportion of primary RNA transcript not undergoing splicing. This observation strongly suggests that there may exist come kinds of interferences with transesterification at the first step of splicing. Overall it can be concluded that K$^{+}$ ion exhibits very unique roles in RNA splicing of tdd gene depending on its concentration.ion.

• Journal of Pharmaceutical Investigation
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• v.4 no.1_2
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• pp.46-54
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• 1974

A new spectrophotemetric method was estalished for the determination of oleic acid. This method is based on the 1,2-dichloroe-thane extraction of the ion-pair formed between methylene blue and oleic acid. But the absorbance of an ion-pair in the 1,2-dichloroe-thane layer was variable with the temperature, the ion-pair was extracted back into a diluted hydrochloric acid solution. The maximum absorbance of the acid extract observed at $660m{\mu}$ and a lineal relationship was observed from the initial amount over the range of $50-800{\gamma}/ml$ of oleic acid in the aqueous phase. The composition ratio of the ion-pair formed between methylene blue and oleic acid was determined to be 2 : 1 by both the mole ratio and continuous variation methods.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.1
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• pp.59-64
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• 2006

The pH-ISE(ion selective electrode) based on tribenzylamine as a hydrogen ion carrier was prepared and its electrochemical characterization was studied. It responded linearly to hydrogen ions in the range of pH 3.1 - pH 11.0 and the Nernstian slope showed 55.0 mV/pH (at $20{\pm}0.2^{\circ}C$), it also showed a fast response time of 8 sec. When it was directly applied to human blood(pH 6.0-8.5), we could get the same satisfying results. A good reproducibility and stability were shown with the precision of 2 mV (${\pm}0.1$). The pH-ISE based on tribenzylamine exhibited biocompatibility in clinical applications.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.499-504
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• 1989

Coloring effect, mechanical properties resulting from silver ions exchange of glasses immersed into the mixed molten salt of KNO3 and AgNO3 were investigated in this study. Ion exchange coloring of glasses made it possible to obtain glasses with a range from yellow to yellowish-brown, and spectral transmittance was investigated. The amount of ion exchange and peneration depth increased with treatment temperature and time. The activation energy decreased with mole fraction of AgNO3. It can be seem that the bending strength of ion exchanged glasses were 3~4 times higher than the parent glass and Ag+ colloids prevented from increasing surface microhardness.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.44.1-44.1
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• 2009

Identification of wave characteristics during current disruption events in the near-Earth geomagnetic tail region (~ 10 RE) is important to understand the substorm onset mechanism. In this paper, linear stability analysis in the ion-cyclotron grequency range, considering temperature anisotropy and cross-field flow is presented. It is found that the ion-cyclotron drift waves propagating in a quasi-perpendicular direction with respect to the ambient magnetic field are characterized by low frequencies ($\omega$ < $0.5{\Omega}ci$), while quasi-parallel waves have frequencies close to the ion-cyclotron frequency ($\omega{\sim}{\Omega}ci$). This finding is consistent with the observation by THEMIS spacecraft of a current disruption event in which a similar high- and low-frequency band structure is also present [A. T. Y. Lui, et al., J. Geophys. Res. 113, A00C06 (2008)]. It is also found that the quasi-perpendicular mode is excited by the ion cross-field flow.

• Archives of Pharmacal Research
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• v.14 no.4
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• pp.285-289
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• 1991

A convenient spectrophotometric method was examined for the determination of amantadine sulfate (AMTS) which has no UV-VIS chromopohores. AMTS was ion-paired quantitatively with methyl orange (MO) at $70^{\circ}C$ for 30 min. The ion-paired complex was extracted with dichloromethane and the absorbance was measured at 421.5 nm. A linear relationship was observed in the range of $2.5{\times}10^{-7}\;M$ to $3.75{\times}10^{-6}\;M$ and the correlation coefficient was 0.999 (n=3). This assay method was applied to the quantification of AMTS in commercial tablet form with good recovery and high precision.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.293-297
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• 1998

The influence of ion implantation on surface properties of polymers was studied. We investigated microhardness, friction, wear and wettablility of polyimide. Energies of 50, 200keV were used with doses range from $1{\times}10^{13} to 1{\times}10^{16} [ions/cm^2]$. The implanted ion species were B, N and Ar. The microhardness of polyimide was increased after implantation for doses of $1{\times}10^{15}\; [ions/cm^2]$. A reduction of the friction coefficient was in most case correlated with a reduction of wear. The contact angles of water for $B^+,N^+$ implanted polyimide decreased from $76^{\circ}C$ to zero, as the fluencies increased at energies of 50 and 200 KeV. However, the contact angle of Ar ion implanted polyimide did not change under ambient room conditions even if the time elapsed. SEM measurement was performed to characterize the modified surface layer.