• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.101-106
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• 1983

It was the purpose of this study to investigate the fracture mode of dental amalgam by observing the crack propagation, and to relate this to the microstructure of the amalgam. Caulk 20th Century Regular, Caulk Spherical, Dispersalloy, and Tytin amalgam alloys were used for this study. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (Capmaster, S.S. White), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12 mm in height and was pressed by the Instron Universal Testing Machine at the speed of 1mm/min with 120Kg. The specimen removed from the mold was stored in the room temperature for a week. This specimen was polished with the emery papers from #100 to #200 and finally on the polishing cloth with 0.06${\mu}Al_2O_3$ powder suspended in water. The specimen was placed on the Instron testing machine in the method similar to the diametral tensile test and loaded at the crosshead speed of 0.05mm/min. The load was stopped short of fracture. The cracks on the polished surface of specimen was examined with scanning electron microscope (JSM-35) and analyzed by EPMA (Electron probe microanalyzer). The following results were obtained. 1. In low copper lathe-cut amalgam, the crack went through the voids and ${\gamma}_2$ phase, through the ${\gamma}_1$ phase around the ${\gamma}$ particles. 2. In low copper spherical amalgam, it was observed that the crack passed through the ${\gamma}_2$ and ${\gamma}_1$ phase, and through the boundary between the ${\gamma}_1$ and ${\gamma}$ phase. 3. In high copper dispersant (Dispersalloy) amalgam, the crack was found to propagate at the interface between the ${\gamma}_1$ matrix and reaction ring around the dispersant (Ag-Cu) particles, and to pass through the Ag-Sn particles. 4. In high copper single composition (Tytin) amalgam, the crack went through the ${\gamma}_1$ matrix between ${\eta}$ crystals, and through the unreacted alloy particle (core).

• Journal of the Korean Society of Radiology
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• v.10 no.5
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• pp.337-341
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• 2016

We measured the neutron capture cross-section of natural Sm(n,${\gamma}$) reaction in the energy regions from 0.003 to 10 eV. The 46-MeV electron linear accelerator of Research Reactor Institute, Kyoto University was used for generating a continuous neutron source. The neutron time-of-flight method was adopted for energy measurement. An assembly of BGO($Bi_4Ge_3O_{12}$) scintillators composed of 12 pieces of BGO crystals measured prompt gamma rays from Sm(n,${\gamma}$) reaction. The BGO assembly was located at a distance of $12.7{\pm}0.02m$ from the neutron source. In order to determine the neutron flux impinging on the Sm, the $^{10}B(n,{\alpha}{\gamma})^7Li$ standard cross-section were used. Natural Sm(n,${\gamma}$) reaction measurement result of the neutron capture cross-section was compared with the results of evaluation of the BROND-2.2 and the previous experimental data of J. C. Chou and V. N. Kononov.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.262.1-262.1
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• 2014

Lipid peroxidation induces functional deterioration of cell membrane and induces cell death in extreme cases. These phenomena are known to be related generally to the change of physical properties of lipid membrane such as decreased lipid order or increased water penetration. Even though the electric property of lipid membrane is important, there has been no report about the change of electric properties after lipid peroxidation. Herein, we demonstrate the molecular energy band change in red blood cell membrane through peroxidation by air-based atmospheric pressure DBD plasma treatment. Ion-induced secondary electron emission coefficient (${\gamma}$ value) was measured by using home-made gamma-focused ion beam (${\gamma}$-FIB) system and electron energy band was calculated based on the quantum mechanical Auger neutralization theory. The oxidized lipids showed higher gamma values and lower electron work functions, which implies the change of surface charging or electrical conductance. This result suggests that modified electrical properties should play a role in cell signaling under oxidative stress.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1255-1257
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• 2005

The increase of secondary electron-emitting coefficient is effective to reduce the discharge voltage as well as to improve the luminance efficiency of PDP. We investigated the properties of ${\gamma}$ with composition and different dielectric constants, and the microstructure of dielectric after ion collision. As a result the dielectric of PbO system showed higher ${\gamma}$ compared with Pb-free system. However, there was no difference in ${\gamma}$ when the MgO protective layer was covered.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1758-1771
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• 2017

In this study, to determine the most effective alloy for shielding against gamma-rays, the gamma-ray shielding parameters of six types of cerrobend alloys have been investigated. Gamma-ray interaction with the cerrobend alloys has been discussed mainly in terms of total mass attenuation coefficient (${\mu}_t$), half value layer (HVL), tenth value layer (TVL), effective atomic number ($Z_{eff}$), and effective electron density ($N_{eff}$). These parameters have been calculated by theoretical approach using the ParShield program in a photon energy range between 0.1 MeV and 100 GeV. The dependence of these parameters on the incident photon energy and chemical composition of the cerrobend alloys has been studied.

• Journal of Korea Foundry Society
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• v.19 no.6
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• pp.472-483
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• 1999

The effects of rapid solidification and Cr addition to the microstructure variations of the rapid solidified Ti-48Al-xCr(X = 2,4,6) alloys have been investigated using X-ray diffractometry, optical microscopy, scanning electron microscopy and transmission electron microscopy. The segregated coarse ${\gamma}$ phase was eliminated and the microstructure was refined by rapid solidification of the cooling rate of $10^4-10^6\;^{\circ}C/sec$. The lattice parameters and tetragonality of ${\gamma}$ phase decrease with the increase Cr content and by the rapid solidification. Non-equilibrium phase ${\alpha}$ remains at room temperature condition, which would be resulted from the restriction of phase transformation ${\alpha}$ to ${\alpha}_2+{\gamma}$.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.216-223
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• 2017

In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and $10^{th}$ value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

• Journal of Radiation Industry
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• v.4 no.4
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• pp.385-389
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• 2010

In this study, the effect of the concentration of carboxymethylcellulose (CMC) solution on the degradation by irradiation was investigated. The CMC solutions with different concentrations of 3%, 4%, 5%, 6% and 7% were irradiated at the doses of 5, 10, 15, 20, 25 and 30 kGy with gamma ray or electron beam, and the viscosity of CMC solution was measured. The viscosity of the CMC solutions was decreased with an increase in the irradiation dose, but the extent of the degradation by an irradiation was found to be decreased with an increase of the CMC concentration in the solution. The dependency of the irradiation sources showed that an electron beam radiation had degraded the CMC less severely than gamma ray.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.716-719
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• 2007

The effects of the evaporation rate of MgO films using an electron beam on the MgO properties and the discharge characteristics of a plasma display panel (PDP) were investigated and analyzed. MgO films were deposited with the various MgO evaporation rates. The MgO properties such as the crystal orientation, the surface roughness, and the film structure were inspected using XRD (X-ray diffraction), AFM (atomic force microscopy). From the experiments and Paschen law, the maximum value of the secondary electron emission coefficient $({\gamma})$ was obtained at the evaporation rate of $5{\AA}/sec$. The XRD results and cathode-luminescence (CL) spectra show the ${\gamma}$ values are correlated with F/F+ centers of the molecular structure of MgO films. The minimum firing voltage and the maximum luminous efficiency were obtained at an evaporation rate of $5{\AA}/sec$. In the MgO film deposited at $5{\AA}/sec$, the (200) orientation and F+ center were most intensive.

• Food Science and Preservation
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• v.10 no.2
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• pp.206-212
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• 2003

Comparative effects of electron beam and gamma-ray irradiation (25 ∼15 kGy) were investigated on saponin stability and some physiological and chemical properties of white and red ginseng powders. Saponin components were found stable upon irradiation of both energies when determined by TLC and HPLC, after 4 months of storage at room temperature as well as immediately after treatment The contents of total phenolics and acidic polysaccharides of the samples were higher in red ginseng than in white. Polysaccharide contents increased with irradiation doses. Amylase activity of white ginseng was stimulated by irradiation but decreased with the lapse of storage time. There were no apparent differences in electrophoresis patterns of extracted proteins depending on irradiation doses and energy sources.