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Ruamnikhom, R.,Limsuwan, P.,Horprathum, M.,Chanthima, N.,Kim, H. J.,Ruengsri, S.,Kaewkhao, J. Hindawi Limited 2014 Advances In Materials Science And Engineering Vol.2014 No.-
<P>Physical, optical, and luminescence properties of Nd<SUP>3+</SUP>ions in bismuth barium borate glass system were studied. The glasses prepared by a melt quenching method were doped at various Nd2O3concentrations in compositions (40-<I>x</I>)B2O3 : 40Bi2O3 : 20BaO : <I>x</I>Nd2O3(where<I>x</I>= 0.00, 0.50, 1.00, 1.50, 2.00, and 2.50 in mol%). Luminescence properties of the glasses were studied under two excitations of 585 and 750 nm for downconversion. From both excitations, the results show emission bands in NIR region corresponding to the transitions between<SUP>4</SUP>F3/2 → <SUP>4</SUP>I9/2(900 nm),<SUP>4</SUP>F3/2 → <SUP>4</SUP>I11/2(1,060 nm), and<SUP>4</SUP>F3/2 →<SUP> 4</SUP>I13/2(1,345 nm). The luminescence intensity obtained with 585 nm excitation was stronger than 750 nm, with the strongest NIR emission at 1,060 nm. The upconversion emission spectrum exhibits strong fluorescence bands in the UV region at 394 nm ( <TEX>$ \lambda _{\text{ex}}=591$</TEX> nm). The processes are associated with excited state absorption (ESA) from<SUP>4</SUP>F3/2level to<SUP>4</SUP>D3/2level and it is the radiative decay from the<SUP>4</SUP>D3/2to ground levels (<SUP>4</SUP>D3/2 → <SUP>4</SUP>I13/2) which are responsible for the emission at 394 nm.</P>
T. Charinpanitkul,P. Limsuwan,C. Chalotorn,N. Sano,T. Yamamoto,P. Tongpram,P. Wongsarivej,A. Soottitantawat,W. Tanthapanichakoon 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.1
Synergetic removal of aqueous phenol by decomposition with ozone and adsorption on activated carbon was experimentally investigated. To enhance phenol removal performance, two activated carbons (AC1 and AC2) with BET surface areas of 1106 and 1150 m2 g1 and average pore diameters of 2.3 and 1.7 nm, respectively, were employed. While the slowest initial removal of phenol was achieved with introduction of ozone only, the much better removal of phenol was obtained with utilization of activated carbon with ozone. Some intermediate products, which were detected as total organic carbon (TOC), were found to remain even after phenol was completely decomposed. Regarding to higher mesopore fraction, AC1 could better remove intermediates than AC2. With the synergetic performance of AC1 and ozone it was found that the highest removal of phenol and TOC was up to 100% and 89%, respectively.
Micro-mechanical modeling for compressive behavior of concrete material
Haleerattanawattana, P.,Senjuntichai, T.,Limsuwan, E. Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.18 No.5
This paper presents the micro-mechanical modeling for predicting concrete behavior under compressive loading. The model is able to represent the heterogeneities in the microstructure up to three phases, i.e., aggregate particles, matrix and interfaces. The smeared crack concept based on non-linear fracture mechanics is implemented in order to formulate the constitutive relation for each component. The splitting tensile strength is considered as a fracture criterion for cracking in micro-level. The finite element method is employed to simulate the model based on plane stress condition by using quadratic triangular elements. The validation of the model is verified by comparing with the experimental results. The influence of tensile strength from both aggregate and matrix phases on the concrete compressive strength is demonstrated. In addition, a guideline on selecting appropriate tensile strength for each phase to obtain specified concrete compressive strength is also presented.
Interaction of 662 keV Gamma-rays with Bismuth-based Glass Matrices
J. Kaewkhao,K. Kirdsiri,P. Limkitjaroenporn,P. Limsuwan,박정민,김홍주 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.22
In this work, the Bi_2O_3-SiO_2 glass system was synthesized by using the melt-quenching method. The radiation shielding properties of the glass samples at various levels of bismuth content were measured at 662 keV by usage a ^(137)Cs radioactive source, and comparisons were made with values theoretically calculated by usage WinXCom. The experimentally obtained values were generally in good agreement with the theoretical ones. Furthermore, a comparison was made to a lead-borate glass system with the same level of additive. The radiation shielding properties were found to be improved with increasing Bi_2O_3 concentration. The different values of Compton scattering yielded a higher total mass attenuation coefficient for the bismuth-silicate glass than for the bismuth-borate glass. These results reflect the potential usefulness of bismuth-based glasses as new materials for lead-free radiation-shielding glasses.
J. M. Park,P. Limsuwan,J. Kaewkhao,김홍주,김성환 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.2
Bismuth-borate glass scintillators have high density and good radiation hardness. Thus, if they are highly luminescent, they can be applied in astrophysics, high-energy and nuclear physics, homeland security, radiation detection and medical imaging. Bismuth-borate glasseswith the formula xBi<sub>2</sub>O<sub>3</sub>:(100 − x)B<sub>2</sub>O<sub>3</sub> (x = 30, 50, and 66.7 mol%) were fabricated and doped with Nd, Er, Dy, Pr, Sm, Ho, Gd, and Ce in different dopant concentrations by using the melt-quenching technique. The X-ray emission spectra for the bismuth-borate glasses were measured and showed that only Sm-, Dy-, and Nd-doped glass scintillators had noticeable luminescence. Also, we measured the photo-luminescence and the proton-induced emission spectra. We obtained the result that Sm- and Dy- doped glass scintillators emitted luminescence. The emission peaks of the Sm- doped glass were 569, 598, 641, and 708 nm and were due to (<sup>4</sup>G<sub>5/2</sub> → <sup>6</sup>H<sub><i>J</i></sub> ) (<i>J</i> = 5/2, 7/2, 9/2, 11/2) transitions, respectively. The emission peaks of the Dy- doped glass were at 485 nm (<sup>4</sup>F<sub>9/2</sub> → <sup>6</sup>H<sub>15/2</sub>), 575 nm (<sup>4</sup>F<sub>9/2</sub> → <sup>6</sup>H<sub>13/2</sub>), 660 nm (<sup>4</sup>F<sub>9/2</sub> → <sup>6</sup>H<sub>11/2</sub>), and 755 nm (<sup>4</sup>F<sub>9/2</sub> → <sup>6</sup>H<sub>9/2</sub> + <sup>6</sup>H<sub>11/2</sub>), and that of the Nd-doped glass was at 895 nm due to the (<sup>4</sup>F<sub>3/2</sub> → <sup>4</sup>I<sub>9/2</sub>) transition. The luminescence intensities were compared in terms of different Bi concentrations and dopant concentrations.
X-ray and Proton Luminescences of Bismuth-borate Glasses
박정민,김홍주,김성환,천종규,J. Kaewkhao,P. Limsuwan,S. Insiripong 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.22
Heavy scintillators with good radiation hardness and low cost can be applied in high -energy physics, astrophysics, homeland security and radiation detection. It is possible to make heavy-iondoped glass scintillators that can meet these requirements. We fabricated bismuth-borate glasses, Bi_2O_3(30) : B_2O_3(70), doped with CeO_2, Nd_2O_3, Er_2O_3, Dy_2O_3, and Pr_2O_3 in difference concentrations by using the melt-quench technique. An X-ray luminescence study showed that only Dy_2O_3-doped glass emitted luminescence with a peak at 575 nm. Absorption spectra o f the Dy_2O_3-doped glass were studied to understand the optical property. Proton luminescence of Dy_2O_3-doped glass was studied by using the 45-MeV proton beam from the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The results for the proton and the X-ray luminescences were compared.