• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.59-60
• /
• 2015

High resolution, multi-wavelength images from the Dutch Open Telescope were used to study the detailed mechanisms that might be involved in the multiple layer solar atmosphere observed in high cadence multi-wavelength observations. With the exceptional data observed for active region NOAA 10789 on 2005 July 13th, we study the changing pattern of the fibril using multi-wavelength tomography of the $H{\alpha}$ line center and blue wing, Ca II H, and the G Band. It is believed that a long fibril that is rooted in the umbra, with longer apparent periodicity, may be due to morphological changes. To determine this, we conduct phase difference and coherency analysis between points along the fibril to understand how the wave propagates.

• Journal of Magnetics
• /
• v.22 no.1
• /
• pp.100-103
• /
• 2017

We studied the microstructure and magnetic properties of Fe nanosized powder synthesized by the pulsed wire evaporation method. The x-ray diffraction spectrum confirmed that this powder had a pure ${\alpha}$-Fe phase. Scanning electron microscope and transmission electron microscope measurements indicated that the prepared powder had uniform spherical shape with core-shell structure. The mean powder size was about 35 nm and the thickness of the surface passivation layer was about 5 nm. Energy dispersive X-ray spectroscopy measurement indicated that the surface passivation layer was iron oxide. Magnetic field dependent magnetization measurement at room temperature showed that the maximum magnetization of the prepared powder was 177.1 emu/g at 1 T.

• Journal of Plant Biology
• /
• v.37 no.4
• /
• pp.397-402
• /
• 1994

Possible roles of polyamines in the inhibition of cell elongation in Ranunculus petioles were investigated. Exogenously apoplied polyamines greatly inhibited the auxin-induced petiole growth, while treatment of the tissue with $\alpha$-difluoromethylarginine, the inhibitor of putrescine biosynthesis, further enhanced the growth in the presence of IAA. Inhibitory effect of spermine can also be apparent for fusicoccin-induced elongation, but not for growth induced by a low pH. Spermine also suppressed the ethylene-enhanced growth in the presence of auxin. Using computer-based video digitizer system, the inhibitory effects of spermine on petiole growth were kinetically analyzed. Auxin-induced growth was characterized by an initial and transient growth with a highly elevated rate followed by a steady growth with a slightly reduced rate. Spermine treatment was found to shorten the duration of the initial phase of growth, and to reduce the rates of both the initial and steady growth as well. The latent period for auxin induction was not affected by spermine.

• Archives of Pharmacal Research
• /
• v.22 no.6
• /
• pp.575-578
• /
• 1999

Derivatives of elema-1,3-diene were synthesized in several steps as polar analogs of $\beta$-elemene, antitumor agent under clinical phase. The lactone ring of compound 1 was opened by LiAlH4 to give diol 2 which was selectively protected by TBDPSCI. After acetylation of the secondary alcohol, the acetylated product was ozonolyzed and reduced to give elemene derivative 4 which was converted to diolefin 8 via selenides subsequent deprotection by tetrabutylammonium fluoride gave two compounds 9, 10.

• Korean Journal of Materials Research
• /
• v.15 no.12
• /
• pp.760-764
• /
• 2005

The influences of the oxidant($O_2\;and\;O_3$) on the FeOOH formation were studied with fixed $FeSO_4{\cdot}7H_2O$ concentration (0.5M) and NaOH equivalent ratio(0.5). The characteristics of the synthesized powders were evaluateed by XRD, and equantitative phase analysis. $\alpha-FeOOH$ (Geothite) and/or $\gamma-FeOOH$ was promoted when $O_3$ was used as a oxidant which is stronger oxidizing agent than $O_2$.

• Korean Journal of Materials Research
• /
• v.14 no.5
• /
• pp.353-357
• /
• 2004

The influences of the ozone oxidation, reaction temperature and NaOH equivalent ratio on the iron oxide formation were studied with fixed ferrous sulfate concentration(0.5M $FeSO_4$ㆍ$7H_2$O). Geothite($\alpha$-FeOOH) and/or Magnetite ($Fe_3$$O_4$) were synthesized depending on the reaction conditions. The characteristics of the synthesized powders were evaluated by XRD, SEM and quantitative phase analysis. The synthetic conditions to get Goethite were quite different from the results of Kiyama's and the Goethite was conveniently synthesized at low temperature and at low NaOH equivalent ratio.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.1
• /
• pp.51.1-51.1
• /
• 2011

Red dusty Active Galactic Nuclei (AGNs) are suspected to mid-stage between ULIRG and AGN phase. As well as, red AGNs are suspected that they have more than 50% of whole AGN population. In order to understand the character of red AGNs, Black Hole (BH) mass of red AGN is a key property and can not measured by existing method such as reverberation mapping and single epoch method. Thus we still don't know their character and properties in clearly. To estimate properties of red AGNs without the effect of dust-obscuration, we have obtained Near InfraRed (NIR) spectra of 31 reverberation mapped AGNs and 49 Palomar-Green(PG) Quasi-Stellar Object (QSO) by using the infrared camera (IRC) for AKARI with unique wavelength range $2.5-5.0{\mu}m$. From this spectra, we measured the FWHM and luminosity of brackett ${\alpha}$ and ${\beta}$ at 4.0, 2.6 micron meter for deriving new BH mass estimators based on the properties of Brackett line emission.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.5
• /
• pp.398-405
• /
• 2002

The degradation characteristics of MgO additive for the ZnO ceramic devices fabricated by the standard ceramic techniques are investigated in this study. These devices were made from basic Matsuoka's composition. Especially, MgO was added to analyze the degradation characteristics and devices were sintered in air at $1200^{\circ}C$. The conditions of DC degradation test were $115\pm2^{\circ}C$ for 12h. Using XRD and SEM, the phase and microstructure of samples were analyzed, respectively. The elemental analysis in the microstructures was performed by EDS, E-J analysis was used to determine $\alpha$. Frequency analysis was accomplished to understand the relationship between $R_G$ and $R_B$ with the electric stress at the equivalent circuit.

• Journal of Surface Science and Engineering
• /
• v.48 no.3
• /
• pp.110-114
• /
• 2015

The effect of hot-dip aluminizing on the corrosion of the low carbon steel was studied at $650-850^{\circ}C$ for 20-50 h in $N_2/0.5%\;H_2S$ gas. The aluminized steel consisted primarily of the Al topcoat and the underlying Al-Fe alloy layer. Aluminizing drastically improved the corrosion resistance by forming the ${\alpha}-Al_2O_3$ surface scale. Without aluminizing, the steel formed nonadherent, fragile, thick scales, which consisted of FeS as the major phase and iron oxides such as FeO, $Fe_3O_4$ and $Fe_2O_3$ as minor ones.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05c
• /
• pp.107-110
• /
• 2003

In this paper, We introduced that the method for determing the dielectric relaxation time $\tau$ of floating monolayers on water interface. Displacement current flowing across monolayers is analyzed using a rod-like molecular model. It is revealed that the dielectric relaxation time $\tau$of monolayers in the isotropic polar orientational phase is determined using a linear relationship between the monolayer compression speed $\alpha$ and the molecular area Am. here Displacement current gives a peak at A = Am. The dielectric relaxation time $\tau$ of organic monolayers was examined on the basis of the analysis developed here.