• The Journal of Korean Society for Radiation Therapy
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• v.25 no.1
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• pp.25-31
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• 2013

Purpose: The aim of this study is to evaluate the dosimetric properties of robust planning strategy for plain intensity-modulated proton therapy (IMPT) taking into account of the uncertainties of effective proton range and set up error as compared to photon intensity-modulated radiation therapy (photon-IMRT) in prostate cancer treatment. Materials and Methods: The photon-IMRT (7 beams, step & shoot), plain-IMPT (2, 4, and 7 portals), and robust- IMPT plans, which was recalculated the plain-IMPT based on the uncertainties of range error (${\pm}5%$) and set up error (0.5 cm), were evaluated for five prostate cancer patients prescribed by 70 Gy/35 fractions. To quantitatively evaluate the dose distributions, several parameters such as maximum dose, minimum dose, mean dose, conformity index (CI), and homogeneity index (HI) for PTV as well as dose-volume index of VxGy for OARs were calculated from dose-volume histograms. Results: Robust-IMPT showed superior dose distributios in the PTV and OARs as compared to plain-IMPT and photon-IMRT. Like plain-IMPT, robust-IMPT were resulted in dose fluctuation around OARs, while better homogeneity and conformity in PTVs and lower mean dose in OARs as compared to photon-IMRT. Conclusion: In consideration with the effective range correction and set up movement using robustness in IMPT plan, the dosimetric uncertainties from plain-IMPT could substantially reduce and suggest more effective solutions than photon-IMRT in prostate cancer treatment.

• Progress in Superconductivity
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• v.14 no.2
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• pp.96-98
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• 2012

Bias current dependence of a superconducting strip photon detector is studied in the wavelength range of 405 to 1310 nm. The detector is made of an $MgB_2$ meander pattern with the line width of 135 nm and thickness of 10 nm. At 1310 nm, the detection efficiency exponentially decreases as the bias current decreases. While at 405 nm, the detection efficiency almost saturates in the high bias current region. These features suggest that the intrinsic detection efficiency of the $MgB_2$ detector is high at 405 nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.02a
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• pp.175.2-175.2
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• 2009

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.991-994
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• 2002

Photon mapping is an efficient global illumination technique for realistic image synthesis that has been developed in computer graphics. In this paper, an adaptive photon mapping in the use of automatic differentiation is proposed. Since the automatic differentiation is used when photons emit from the light sources through the scene, we can check the variation of surrounding shape. Therefore, we can decrease the number of photons and generate an image in relatively low computational cost.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.409-412
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• 2005

Free-standing nanoporous alumina membrane microtubes with different shapes (rectangular and cylindrical tubes) and variable dimensions were easily fabricated by direct anodization of the aluminum templates of the specified shapes (strip and wire) and dimensions during the electrochemical reaction.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.231-232
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• 2009

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.719-722
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• 2005

The synthesis of the 3D images is the most important part of the virtual reality. The photon mapping is the best method for reality in the 3D graphics. This paper presents an architecture for photon mapping applications on SOC devices. The proposed architecture reduces the computation time to photonmap search and radiance estimation. Also this architecture is implemented by a SIMD processor which trades parallelism for frequency of operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04a
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• pp.70-71
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• 2009

Photoelectric characteristics of a hydrogenated amorphous silicon thin film transistor(a-Si:H TFT) were obtained for the illumination from various backlight sources and the results were compared and analyzed in terms of the photon energy spectral characteristics of the backlights obtained from the integration of the multiplication of the photon energy and the spectral intensity at etch wavelength. It was possible to conclude that the absorption of illuminated backlight to a-Si:H layer and the generation of electrons and holes are mainly carried out at the wavelength less than 500nm.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1249-1253
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• 2007

Experimental studies on the fabrication of sub-30 nm nanofibers using weakly two-photon induced photopolymerized region have been carried out. For the generation of nanofibers inside or outside microstructures, an over-polymerizing method involving a long exposure technique (LET) was proposed. Such nanofibers can find meaningful applications as bio-filters, mixers, and many other uses in diverse research field. A multitude of nanofibers with a notably high resolution (about 22 nm) in two-photon polymerization was achieved using the LET. Furthermore, it was demonstrated that the LET can be employed for the direct fabrication of various embossing patterns by controlling the exposure duration and the interval between voxels. Thin interconnecting networks are formed regularly in the boundary of the over-polymerized region, which allows for the creation of various pattern shapes. Overall of this work, some patterns including nanofibers are fabricated by the LET.

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.321-328
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• 2011

Various methods have been investigated to increase photon density in soft tissue, an important factor in low-level laser therapy. Previously we developed a compression-controlled low-level laser probe (CCLLP) utilizing mechanical negative compression, and experimentally verified its efficacy. In this study, we used Bezier curves to numerically simulate the skin deformation and photon density variation generated by the CCLLP. In addition, we numerically modeled changes in optical coefficients due to skin deformation using a linearization technique with appropriate parameterization. The simulated results were consistent with both human in vivo and porcine ex vivo experimental results, confirming the efficacy of the CCLLP.