Ex) Article Title, Author, Keywords
Ex) Article Title, Author, Keywords
Abstract : The 2G High-$T_{c}$ superconductor-coated conductors (2G HTS CC) with large aspect ratios have large AC losses for a perpendicular external magnetic field. A reduction of the AC loss is an important issue in 2G HTS CC applications. In a previous study, stacking of HTS CC was found to increase the full penetration field $H_{p}$ and to decrease the AC loss. The AC loss for the maximum applied magnetic field $H_{m}$ below $H_{p}$ was affected by the interval $D$ and the staking number $n$. In this study, to reduce the AC loss, we stacked GdBCO-coated conductors with the same geometries and with regular $D$, and we measured the magnetization curves of the stacked samples at a temperature of 83 K ($t = T/T_{c} = 0.88$). The AC losses were calculated using the experimental results, and the AC losses of the stacked samples were compared with phose for the single-layer sample. We investigated the dependences on $D$ and n of the AC losses of the stacked GdBCO CCs. As the interval decreases, the volume normalized AC loss decreased. In the case of $D$ = 0.10 mm, the AC loss was decreased by 16% and 37% in the 2-layer structure and the 3-layer structure, respectively, compared with the 1-layer structure.
Abstract : In this study, we evaluate the dose distributions of $^{4}$He and $^{6}$He ion beams under the same irradiation settings by using the Monte Carlo method. For the simulations, we defined a water phantom that which includes three normal regions and one target region for measuring the dose deposition in various regions. In addition, we define the $^{4}$He and the $^{6}$He ion beams with specified parameters. Then, we obtain the distributions of the doses and the tracks of $^{4}$He and $^{6}$He ion beams and calculate the dose deposited in each region. The calculated results show that in the proximal volume, lateral volume, distal volume, and target volume, the dose depositions of the $^{4}$He ion beam are 73.77%, 31.44%, 73.5%, and 98.50% of that of $^{6}$He ion beam. In conclusion, we can say from the aspect of physical dose distribution, that the $^{4}$He ion beam is more ideal than the $^{6}$He ion beam. To more objectively evaluate the therapatic effects of $^{4}$He and $^{6}$He ion beams, in our need experiment-based study, we will consider the biological effects of $^{4}$He and $^{6}$He ion beams.
Abstract : We have grown nitrogen-doped titanium dioxide thin films by using DC magnetron sputtering methods. During the growth, the nitrogen flow was altered to adjust the amount of nitrogen into the titanium-dioxide films. By a comparative study of X-ray diffraction and Raman spectroscopy results, we found that the insertion of nitrogen led to a reduction in crystal size/volume, distortion of Ti-O bending, and displacement of Ti atoms. As the nitrogen flow was increased, the degradation of crystal quality became more severe. A blue shift of the optical energy bandgap was observed for the titanium-dioxide films with nitrogen, which is possibly related to quantum-confinement effects.
Abstract : Carbon quantum dots were synthesized using the hydrothermal method with fallen leaves as carbon sources. The chemical structure, particle size and morphology, and luminescent characteristics of the prepared carbon quantum dots were investigated. The particle size and morphology of synthesized carbon dots were observed by using TEM (transmission electron microscopy). The ligand and chemical structures of the carbon quantum dots were confirmed by using FT-IR (Fourier transform infrared spectroscopy). The elemental components of the carbon quantum dots were investigated by using XPS (X-ray photoelectron spectroscopy). The photoluminescence spectrum of carbon quantum dots showed strong cyan fluorescence around 493 nm under 400-nm excitation. A UV blocking film for preventing eye and body damage was fabricated by using the prepared carbon quantum dots. Consequently we confirm the applicability of carbon dot films for shielding from UV light.
Abstract : A new silicon chip (INVESTIGATOR) manufactured for R\&D purposes has 134 mini-matrices with various pixel designs. Each matrix consists of 8 $\times$ 8 pixels, which put out 64 analogue signals at 65 MHz. The silicon pixel design is based on the newest technology of the complementary metal-oxide-semiconductor (CMOS) monolithic active pixel sensor (MAPS), which integrates the silicon sensor and the read-out circuitry in a pixel. The MAPS has advantages of low power consumption, high granularity of a pixel, and fast read-out. In this paper, the charge collection time for different pixel designs and reverse bias voltages is studied by using the INVESTIGATOR. The charge collection time is estimated by fitting the waveform for changing pixel pitch, reverse bias voltage, diameter of collection n-well diode, and spacing. Based on these results, we discuss the dependence of the relative depletion volume and the charge collection time on the pixel geometry.
Eng Chan KIM*
New Phys.: Sae Mulli 2019; 69(3): 221-226
https://doi.org/10.3938/NPSM.69.221
Seong Min JANG, Chul Hong PARK*
New Phys.: Sae Mulli 2019; 69(3): 227-233
https://doi.org/10.3938/NPSM.69.227
Jinu KIM, Ki Hyeon KIM*, Taehoon KIM, Byungmun JUNG
New Phys.: Sae Mulli 2019; 69(3): 234-239
https://doi.org/10.3938/NPSM.69.234