• Analytical Science and Technology
• /
• v.17 no.6
• /
• pp.514-519
• /
• 2004

Soil samples collected from around the BOMARC Missile Site were measured for their activity concentrations and isotopic ratios of Pu and Am isotopes with particle sizes. The activity concentrations of Pu and Am in the BOMARC soil were remarkably higher than the fallout levels, and the activities decreased nearly exponentially with an increasing particle size of the soil due to a decreasing surface area. The activity ratios of Pu-238 / Pu-239, 240, Pu-241 / Pu-239, 240 and Am-241 / Pu-239, 240 observed in the BOMARC soil were much lower than those attributed to the nuclear reprocess plants and the Chernobyl fallout. Also, the atomic ratio of Pu-240 / Pu-239 in the BOMARC soil was remarkably lower than the fallout value influenced by the nuclear weapons testing and the Chernobyl accident. The atomic ratio of Pu-240 / Pu-239 was so close to the value of the weapons grade Pu released from the crash of a B52 plane in the Thule of the Greenland, such that the Pu isotopes detected in the BOMARC soil could have originated from the weapons grade plutonium.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.7
• /
• pp.415-418
• /
• 2015

In this paper, $TiO_2$ based thin-film transistors (TFTs) were fabricated using by an atomic layer deposition with high aspect ratio and excellent step coverage. $TiO_2$ semiconducting layer was deposited showing a rutile phase through the rapid thermal annealing process, and exhibited TFT characteristics with a $200{\mu}m$ channel length of low-leakage currents (none of current flow during off-state), stable threshold voltages (-10 V ~ 0 V), and a much higher on/off current ratio (<$10^5$), respectively.

• Journal of Powder Materials
• /
• v.17 no.4
• /
• pp.270-275
• /
• 2010

Ethylene glycol-based Cu nanofluids were prepared by pulsed wire evaporation (PWE) method. The structural properties of Cu nanoparticles were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The average diameter and Brunauer Emmett Teller (BET) surface area of Cu nanoparticles were about 100 nm and $7.46\;m^2/g$, respectively. The thermal conductivity and viscosity of copper nanofluid were measured as functions of Cu concentration and temperature. As the volume fraction of Cu nanoparticles increased, both the enhanced ratios of thermal conductivity and viscosity of Cu nanofluids increased. As the temperature increased, the enhanced ratio of thermal conductivity increased, but that ratio of viscosity decreased.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.1
• /
• pp.101-105
• /
• 2004

The laser ablation/ionization time-of-flight mass spectrometry is applied to the isotopic analysis of solid samples using a home-made instrument. The technique is convenient for solid sample analysis due to the onestep process of vaporization and ionization of the samples. The analyzed samples were lead, cadmium, molybdenum, and ytterbium. To optimize the analytical conditions of the technique, several parameters, such as laser energy, laser wavelength, size of the laser beam on the samples surface, and high voltages applied on the ion source electrodes were varied. Low energy of laser light was necessary to obtain the optimal mass resolution of spectra. The 532 nm light generated mass spectra with the higher signal-to-noise ratio compared with the 355 nm light. The best mass resolution obtained in the present study is ~1,500 for the ytterbium.

• Journal of Magnetics
• /
• v.5 no.4
• /
• pp.135-138
• /
• 2000

In order to study the effect of the magnetic anisotropy on the giant magnetoresistance in a Co/Cu multilayered system, the angle dependent magnetoresistance (MR) was measured. The experimental results showed that the maximum MR ratio depends on the angle between the direction of the applied field and the easy axis. The angular modulation of the MR ratio can be explained by the alignments of the two 'effective' magnetization vectors that are bound to their own easy axes. Two maxima observed in MR loops at the second antiferromagnetic maximum are discussed in relation to the magnetic anisotropy, The simulated results under the assumption of the existence of two in-plane easy axes in the sample are compared with the experiments.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.18 no.4
• /
• pp.457-464
• /
• 2020

In this study, extraction of uranium(VI) from an aqueous nitric acid solution was investigated using tri-n-butyl phosphate (TBP) as an extractant in an ionic liquid, 1-alkyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide ([Cnmim][Tf2N]). The distribution ratio of U(VI) in 1.1 M TBP/[Cnmim][Tf2N] was significantly high when the concentration of nitric acid was low. The value of the distribution ratio decreased as the concentration of the nitric acid increased at lower acidities, and then increased with a nitric acid concentration of up to 8 M. This can be attributed to the different extraction mechanisms of U(VI) based on nitric acid concentrations. Thus, a cation exchange at low acidity levels and an ion-pair extraction at high acidity levels were suggested as the extraction mechanism of U(VI) in the TBP/[Cnmim][Tf2N] system.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
• /
• pp.307-314
• /
• 2000

In order to study the effect of the magnetic anisotropy on the giant magnetoresistance (GMR), the angle dependent magnetoresistance (MR) was measured. The experimental results show that the maximum MR ratio depends on the angle between the direction of the applied field and that of the easy axis. The angular modulation of the MR ratio can be explained by the alignments of the two 'effective' magnetization vectors that are bound to their own easy axes. The typical property of MR loops at 2$\^$nd/ antiferromangtic maximum (AFM) such as two maxima was discussed in relation with the magnetic anisotropy (MA). The simulated results under an assumption of the two in-plane easy axes, which exist in the sample, were compared with the experiments.

• Journal of Radiation Industry
• /
• v.6 no.3
• /
• pp.257-265
• /
• 2012

This study was carried out to evaluate growth, morphological characteristics, and sugar content among fifty six blackberry (Rubus fructicosus) genotypes derived from gamma-ray treatment (fifty two lines), MNU treatments (three lines), and cross breed R. fructicosus${\times}$R. parvifolius(one line). While 56 genotypes had similar stem diameter with origin variety, the most of mutants showed reduced leaf size. Also, they showed a wide range of variation in fruit size and one hundred fruit weight compared with origin variety. In fruit size and sugar content, two mutant lines showed large fruit sizes and ten mutant lines showed 20% higher sugar content than the original variety. In the correlation analysis, positive relationships were determined between sugar content and stem diameter, fruit length, leaf wide and fruit length/fruit wide ratio. However, leaf length/leaf wide ratio showed a negative correlation with sugar content. The results will be used as fundamental data for Rubus fructicosus breeding program.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.05b
• /
• pp.1033-1039
• /
• 1995

The magnetic system design of the KT-2 tokamak has been performed at KAERI. Design goal has been set to facilitate the so-called "advanced tokamak" studies, which is essential to secure the economy of the tokamak fusion reactors. Design features include a large-aspect-ratio machine configuration, long-pulse operation capability with heavy plasma shaping, hybrid magnetic field control and machine/in-vacuum structures for MHD stability.

• Korean Journal of Metals and Materials
• /
• v.50 no.4
• /
• pp.271-279
• /
• 2012

9-12% Cr steels have been used in thermal power plants which repeat start and stop operations. Major factors of fatigue life are temperature, frequency, stress ratio, holding time, microstructure, and environment. Normally, fatigue life decreases at high temperature, low frequency, high stress ratio, and long holding time conditions. A Mod.9Cr-1Mo steel, called G91, was developed at ORNL (Oak Ridge National Laboratory, USA) and was adopted as a high-temperature structural material in the ASME Code in 2004. However, its low-cycle fatigue and fatigue crack growth characteristics have been rarely studied. In this work, we have investigated the low-cycle fatigue crack growth behaviors of G91 steel under various test conditions in terms of temperature and stress ratio. As temperature and stress ratio increase, the crack growth rate becomes faster and striation distance also increases. On the other hand, the number of branch cracks decreases.