• 한국전자현미경학회:학술대회논문집
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• 2001.11a
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• pp.39-42
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• 2001

• 순환기질환의공학회:학술대회논문집
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• 2003.11a
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• pp.14-15
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• 2003

• Applied Microscopy
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• v.47 no.3
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• pp.101-104
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• 2017

In this investigation, synchrotron X-ray imaging was used to investigate the water distribution inside newly developed gas diffusion media in polymer electrolyte membrane fuel cells. In-situ radiography was used to reveal the relationship between the structure of the microporous layer (MPL) and the water flow in a newly developed MPL equipped with randomly arranged holes. A strong influence of these holes on the overall water transport was found. This contribution provides a brief overview to some of our recent activities on this research field.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.461-463
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• 2004

We investigate the role of secondary electrons in galaxy clusters and in ultra-luminous infrared galaxies (ULIGs). The radio emission in galaxy clusters and ULIGs is believed to be produced by the synchrotron radiation of relativistic electrons. Nonetheless, the sources of these relativistic electrons are still unclear. Relativistic secondary electrons can be produced from the hadronic interactions of cosmic-ray nuclei with the intra-cluster media (ICM) of galaxy clusters and the dense molecular clouds of ULIGs. We estimate the contribution of the secondary electrons in galaxy clusters and ULIGs by comparing observational results with theoretical calculations for the radio emission in these sources. We find that the radio halos of galaxy clusters can not be produced from the secondary electrons; on the other hand, at least for some ULIGs, the radio emission can be dominated by the synchrotron emission of the secondary electrons.

• 순환기질환의공학회:학술대회논문집
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• 2006.04a
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• pp.28-36
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• 2006

The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

• Journal of the Korean Society of Visualization
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• v.8 no.2
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• pp.45-50
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• 2010

The objective of this study is to elucidate the feasibility of synchrotron X-ray micro CT as a non-destructive imaging method to visualize the three-dimensional morphological structures of biological and non-biological samples. The experiments were conducted in 7B2 X-ray micro CT beamline in Pohang Accelerate Laboratory (PAL). A rotational 3-axis stage was specially designed for $0^{\circ}-180^{\circ}$ scanning of test samples. Preliminary tests were performed for opaque samples including a mosquito head, a plant seed and gas diffusion layer (GDL) of polymer electrolyte fuel cell to verify the feasibility of the X-ray micro CT. It visualized clearly the internal structure of all the test samples, supporting its usefulness.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.588-592
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• 1992

The electrons, which are accelerated to nearly light speed from LINAC(Linear Accelerator), put into Storage Ring. And this electrons circulate in an ultra high vacuum chamber and their orbit is controlled by the electromagnets such as DIPOLE, QUADRUPOLE, SEXTUPOLE & CORRECTION MAGNET. Among them, the dipole magnet is to bend the electron and to produce Synchrotron Radiation(S.R). This paper describes the key point during manufacturing of this magnet, and introduce the field measurement results of the HEECO's successful prototype.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1036-1038
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• 2001

The sapphire orientation dependence of the crystallization of ZnO thin films has been studied using real-time synchrotron x-ray scattering. The amorphous ZnO thin films with a 2400-${\AA}$-thick were grown on sapphire(110) and sapphire(001) substrates by radio frequency magnetron sputtering at room temperature. The amorphous ZnO films were crystallization into epitaxial ZnO(002) grains both on the sapphire(110) and on the sapphire(001) substrates. The epitaxial quality, such as mosaic distribution and crystal domain size, of the ZnO grains on the sapphire(110) is high, similar to that of the ZnO grains on the sapphire(001). With increasing the annealing temperature to 600$^{\circ}C$, the mosaic distribution and the crystal domain size of ZnO(002) grains in the film normal direction was improved and decreased, respectively.

• International Journal of Vascular Biomedical Engineering
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• v.4 no.1
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• pp.1-8
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• 2006

The x-ray PIV method was improved for measuring quantitative velocity fields of real blood flows using a coherent synchrotron x-ray source. Without using any contrast media or seeding particles, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells based on a synchrotron x-ray imaging mechanism. The enhanced x-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit. The quantitative velocity fields of blood flows inside opaque tubes were obtained by applying a 2-frame PIV algorithm to the x-ray images of the blood flows. The measured velocity field data show typical features of blood flows such as the yield stress effect. The non-Newtonian flow characteristics of blood flows were analyzed using the x-ray PIV method and the experimental results were compared with hemodynamic models.

• Proceedings of the Korean Magnestics Society Conference
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• 2009.12a
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• pp.204-205
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• 2009

The magnetic properties and structure of FeRh thin film pitaxially grown onto MgO(001) substrate were studied by MPMS(Magnetic Properties Measure System) and in-situ temperature synchrotron XRD(X-ray Diffraction). The transition temperature of FeRh thin films was around 380K. Both M-T curve and d-spacing changes correspond to each other very closely.