• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.355-357
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• 2002

The relationship between magnetic properties of BiPbSrCaCuO superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.137-139
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• 2003

The relationship between magnetic properties of BiPbSrCaCuO superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1421-1423
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• 2003

The relationship between magnetic properties of BiPbSrCaCuo superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.1 s.49
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• pp.43-49
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• 2005

Recently, according as people who have sensitive skin increase, we've been giving more importance to the safety of cosmetics. Especially, preservative is known to be one of the main stimuli which cause side-effects of cosmetics. However, there have been few reports describing cell cytotoxicity, skin penetration, oil-aqueous phase partition, anti-microbial activity of preservatives and their correlation with skin irritation. The study is aimed to develop low irritable preservative system with phenoxyethanol, one of the most commonly used preservatives in cosmetics, considering various factors mentioned above. According to our results of cell cytotoxicity against human normal fibroblasts by means of MTT assay, phenoxyethanol showed the lowest cytotoxicity when compared to other preservatives tested (cytotoxicity: pro-pylparaben > butylparaben > ethylparaben > methylparaben > triclosan > phenoxyethanol), but human patch test for assessing shin primary irritation revealed that phenoxyethanol has higher skin irritation than methylparaben and triclosan. We performed in vitro skin penetration test using horizontal Franz diffusion cells with skin membrane prepared from hairless mouse (5 ${\~}$ 8 weeks, male) to evaluate the rate of skin penetration of preservatives. From the results, we found that the higher irritable property of phenoxyethanol in human skin correlates with its predominant permeability (skin penetration: phenoxyethanol > methylparaben > ethylparaben > propylparaben > butylfaraben > triclosan). Therefore, we made an effort to reduce skin permeability of phenoxyethanol and found that not only the rate of skin penetration of phenoxyethanol but also its skin irritation is dramatically reduced in formulas containing oils with low polarity. In the experiments to investigate the effect of oil polarity on the oil-aqueous phase partition of phenoxyethanol, more than $70\%$ of phenoxyethanol was partitioned in aqueous phase in formulas containing oils with low polarity, while about $70 {\~} 90\%$ of phenoxyethanol was partitioned in oil phase in formulas containing oils with high polarity. Also, in aqueous phase phenoxyethanol showed greater anti-microbial activity. Conclusively, it appears that we can develop less toxic preservative system with reduced use dosage of phenox-yethanol and its skin penetration by changing oil composition in formulas.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1207-1210
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• 2003

The effect of solvent structure on the slope in the plot of ln K vs. solute carbon number was examined. It was found that the free energy of methylene group transfer from the gas phase into a solvent was always negative and that the absolute magnitude of interaction free energy between the methylene group and the solvent was always larger than the absolute magnitude of cavity formation free energy of the methylene group in the solvent. Thus, the slope in the plot of ln K vs. solute carbon number was always positive and its value decreases with increase of solvent polarity since the cavity formation energy of the CH₂ unit increases with increase of solvent polarity while the dispersive interaction energy of the CH₂ unit is virtually invariant. We also examined the effect of sequential addition of CH₂ unit to a solvent molecule upon ln K for three homologous series of solvents: n-alkanes, n-alcohols, and n-nitriles. Characteristic trends in the plots of ln K vs. solvent carbon number were observed for individual solvent groups. A decrease of ln K with solvent carbon number was observed for n-alkanes. An abrupt increase in ln K followed by levelling off was observed for n-alcohols while a final slight decrease in ln K after an abrupt increase followed by rapid levelling off was noted for n-nitriles. All of theses phenomena were found related to variation in cavity formation energy. It was clearly shown that a structural change of a polar solvent by sequential addition of CH₂ units causes an abrupt polarity decrease initially, then gradual levelling off, and finally, conversion to a virtually nonpolar solvent if enough CH₂ units are added.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.71-76
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• 2007

We have demonstrated the resonant resistance pattern changes of the polymer film in the quartz crystal analysis by the function of the molecular polarity phase transition phenomena. PVA and PMMA/PVAc blend films were used as hydrophilic and/or hydrophbic film, respectively. In the comparison between the hydrophilic shows the pattern changes near by the phase transition temperature. For more detailed explanation, the static capacity in the oscillation parameter was measured and the morphology of Au quartz crystal electrode was studied by AFM. It is suggested that the different resonant resistance pattern change is reliable in the condition of different polarity, and the conclusion is important to analysis of the real mechanism a normal quartz crystal experiments.

• Journal of the Korean Chemical Society
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• v.37 no.12
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• pp.1025-1034
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• 1993

We have measured ${\pi}^*$, $\alpha$ and $\beta$ polarity parameters of 2-propanol / hexane and ethyl acetate / hexane mixed solvents over the entire range of composition. For the ethyl acetate / hexane system, only ${\pi}^*$ and $\beta$ were measured since $\alpha$ of these mixed solvents are defined zero. We have corrected the measured polarity parameters to obtain consistent data with the existing literature data assuming a good linear correlation between the measured and the true values. The variation patterns are consistent with the expected trends based on the chemistry of the solvent components. The general trends of the two solvent systems are summarized as follows. ${\pi}^*$ merely increases as the content of the more polar solvent increases while $\alpha$ and $\beta$ increase with the increase of the content of the more polar solvent, then decrease upon continuing addition of the more polar solvent.

• Economic and Environmental Geology
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• v.23 no.1
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• pp.81-86
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• 1990

Palemagnetic study on the Deadong Super Group in the Mungyong area has been carried out to obtain the direction of NRM and virtual geomagnetic pole(VGP), and to investigate geomagnetic stratigraphy and geotectonic evolution. Twenty eight core specimens from five sites in Dangog and Bongmyongsan Formations yield magnetically stable results by thermal demagnetization test. Mean declination and inclination of Dangog and Bongmyongsan formations are $52.4^{\circ}E$ and $-57.3^{\circ}$, respectively, which indicate reversal polarity. VGP is located at $1.2^{\circ}N$ in latitude and $269.4^{\circ}E$ in longitude, which is quite different from those of other contemporary formations in China. This suggests that the study area has suffered from differnt tectonic movement caused by Daebo Orogeny occurred in the Korean Peninsula during post-Daedong and pre-Kyongsang Systems. As compared VGP of Daedong Super Group in the Mungyong area with wordwide Mesozoic paleomagnetic polarity stratigraphy, it is correlated with the reverse Epoch in the Graham normal interval. This suggests that the time of formations of Dangog and Bongmyongsan is in the age of 190-195 my.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.58.2-58.2
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• 2018

Theoretically, the magnetic helicity transport flux through the solar surface into the upper atmosphere can be estimated indefinitely precisely by magnetic field footpoint tracking if the observational resolution is infinitely fine, even with magnetic flux emergence or submergence. In reality, the temporal and spatial resolutions of observations are limited. When magnetic flux emerging or submerging, the footpoint velocity goes to infinity and the normal magnetic field vanishes at the polarity inversion line. A finite observational resolution thus generates a blackout area in helicity flux estimation near the polarity inversion line. It is questioned how much magnetic helicity is underestimated with a footpoint tracking method due to the absence of information in the blackout area. We adopt the analytical models of Gold-Hoyle and Lundquist force-free flux ropes and let them emerging from below the solar surface. The observation and the helicity integration can start at different emerging stages of the flux rope, i.e., the photospheric plane initially cuts the flux rope at different levels. We calculate the magnetic helicity of the flux rope below the photospheric level, which is eventually to emerge, except the helicity hidden in the region to be swept by the blackout area with different widths. Our calculation suggests that the error in the integrated helicity flux estimate is about half of the real value or even larger when small scale magnetic structures emerge into the solar atmosphere.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.91-98
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• 2010

Neurostimulation approaches have been developed and explored to modulate neuroplastic changes of cortical function in human brain. As one of the most primary noninvasive tools, transcranial direct current stimulation (tDCS) was extensively studied in the field of neuroscience. The alternation of cortical neurons depending on the polarity of the tDCS has been used for improving cognitive processing including working memory, learning, and language in normal individuals, as well as in patients with neurological or psychiatric diseases. In addition, tDCS has great advantages: it is a non-invasive, painless, safe, and cost-effective approach to enhance brain function in normal subjects and patients with neurological disorders. Numerous previous studies have confirmed the efficacy of tDCS. However, tDCS has not been considered for clinical applications and research in the field of physical therapy. Therefore, this review will focus on the general principles of tDCS and its related application parameters, and provide consideration of motor behavioral research and clinical applications in physical therapy.