• Journal of Korean Elementary Science Education
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• v.34 no.4
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• pp.357-371
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• 2015

Even after learning electric current, elementary school students have various non-scientific conceptions and difficulties. Because flow of charge is not visible. Also elementary school students do not learn theory but phenomena, so they cannot transfer theoretical perspective to new situation. In this research, we have designed instruction based on PhET simulation visualizing flow of electric charge and applied it to 37 science-gifted students in elementary school for measuring conceptual understanding. As a result, six out of the seven Hake gains of question set are high gain and just one is middle gain because the students have understood the flow pattern of the charge through circuit elements such as light bulbs, wire, as well as battery with PhET simulation and it gives a chance to create various questions spontaneously about electric current. Also they become able to do spontaneous mental simulation without PhET simulation about flow of charges. This research, suggest that developed materials using PhET simulation could be used as not only program for gifted students in elementary school, but also the electrical circuit section in an elementary science curriculum.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.74-84
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• 2004

Purpose: Since I-125 emits low energy (27-35 keV) radiation, thinner crystal and collimator could be employed and, hence, it is favorable to obtain high quality images. The purpose of this study was to derive the optimized parameters of I-125 SPECT using a new simulation tool, GATE (Geant4 Application for Tomographic Emission). Materials and Methods: To validate the simulation method, gamma camera developed by Weisenberger et al. was modeled. Nal(T1) plate crystal was used and its thickness was determined by calculating detection efficiency. Spatial resolution and sensitivity curves were estimated by changing variable parameters for parallel-hole and pinhole collimator. Peformances of I-125 SPECT equipped with the optimal collimator were also estimated. Results: in the validation study, simulations were found to agree well with experimental measurements in spatial resolution (4%) and sensitivity (3%). In order to acquire 98% gamma ray detection efficiency, Nal(T1) thickness was determined to be 1 mm. Hole diameter (mm), length (mm) and shape were chosen to be 0.2:5:square and 0.5:10:hexagonal for high resolution (HR) and general purpose (GP) parallel-hole collimator, respectively. Hole diameter, channel height and acceptance angle of pinhole (PH) collimator were determined to be 0.25 mm, 0.1 mm and 90 degree. The spatial resolutions of reconstructed image of the I-125 SPECT employing HR:GP:PH were 1.2:1.7:0.8 mm. The sensitivities of HR:GP:PH were 39.7:71.9:5.5 cps/MBq. Conclusion: The optimal crystal and collimator parameters for I-125 Imaging were derived by simulation using GATE. The results indicate that excellent resolution and sensitivity imaging is feasible using I-125 SPECT.