• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.49-49
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• 2006

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1378-1383
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• 2018

Multi-wavelength holography has a better axial range than single-wavelength holography, thus allowing unambiguous phase imaging. Noise amplification is the limiting factor in multi-wavelength holography as noise is amplified by a factor equivalent to the magnification of the wavelengths. Here, we propose a new algorithm to remove noise amplification in multi-wavelength holography. The proposed method does not use phase unwrapping and removes $2{\pi}$ ambiguities. Experiments and numerical simulations indicated that the proposed method is fast, has low noise, and is useful for measuring samples with arbitrary step heights.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.04a
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• pp.442-444
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• 2008

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.117-122
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• 2002

Contrast-enhanced MR angiography has become a widely used method useful for clinical diagnosis. Early studies identified a number of technical issues, and many of these have been addressed with various MRI physics innovations over the last several years. The quality of the results is high enough that CE MRA is replacing conventional x-ray angiography methods at many institutions. Ongoing research is expected to provide further improvements in performance, most notably in additional reductions in examination time, in time-resolved 3D imaging, and in improved imaging of the peripheral vasculature with extended fields of view.

• Journal of Magnetics
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• v.7 no.3
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• pp.94-97
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• 2002

The dependence on nickel oxide thickness and a ferromagnetic layer thickness in unidirectional and isotropic exchange-coupled NiO/NiFe(Fe) bilayer films was investigated by magnetic force microscopy to better understand the relation between magnetic domain structure and exchange biasing at microscopic length scales. As the NiO thickness increased, the domain structure of unidirectional biased films formed smaller and more complex in-plane domains. By contrast, for the isotropically coupled films, large domains generally formed with increasing NiO thickness including a cross type domain with out-of plane magnetization orientation. The density of the cross domain is proportional to exchange biasing field, and the fact that the domain mainly originated from the strongest exchange coupled region was confirmed by imaging in an applied external field during a magnetization cycle.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.167-171
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• 2015

Quantum-confined nanostructures open up additional perspectives in engineering materials with different electronic and optical properties. We have fabricated unique cation-exchanged CdS and CdS/CdSe quantum dots and measured their first four exciton transitions. We demonstrate that the relationship between electronic transitions and charge-carrier distributions is generalized for a broad range of core-shell nanostructures. These nanostructures can be used to further improve the performance in the fields of bio-imaging, light-emitting devices, photovoltaics, and quantum computing.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.37.2-37.2
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• 2010

The IMS (Infrared or Intermediate-wide, Medium-deep Survey) program for the search of z~7 quasars has been running since last year. In order to discover enough number of quasars at z~7, a strategy sufficing both survey area (~150 square deg.) and image depth (23 AB mag in J filter), together with using existing multi-wavelength data is chosen. We have been carrying imaging observations with the UKIRT 4m telescope, now covering ~50 square deg. (including UKIDSS survey area) of J-band data. We then used selection in color-color space to choose high-z quasar candidates having the rest-frame Ly-alpha break, and to exclude contamination from stars and galaxies at low-z. We show quasar candidates of redshift z~7 and z~6, out of 25 square deg. data analyzed, and note implications and future plans.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.427-428
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• 1999

• Journal of the Optical Society of Korea
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• v.3 no.2
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• pp.41-46
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• 1999

Spatial and temporal dynamics arising in a photorefractive crystal(BaTiO3) during the process of double phase conjugation was studied experimentally. We studied the dynamical effects caused by the buildup of the diffraction grating and turn on of phase conjugated beams, as well as the spatial effects caused by the finite transverse coupling of beams and the propagation direction of beams. We observed conical emission in DPCM. We believe that various temporal and spatial instabilities are due to movement of the nonlinear grating. For a real beam coupling and constructive interaction of interference fringes in the crystal, we observed steady, periodic, irregular temporal behavior. And, by the calculation of the correlation index, we found that the spatial correlation decreased as the transverse interaction region was increased.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.44.1-44.1
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• 2018

Since its installation on March 27th, 2018, the SAO 1-m telescope has been operating for about 5 months. We report first results of these observations in this presentation. Sample images were taken with a $4096{\times}4096$ CCD camera (Field of view of ${\sim}21{\times}21arcmin^2$) and their characteristics such as seeing value, and limiting magnitudes are presented. The best seeing value is 0.85 arcsecond on July $16^{th}$, 2018. We find that the 5 sigma detection limit is about 20 magnitude AB in B, V, R, I bands with about 10-20 min exposures. We will also briefly introduce the spectrum of a faint transient taken with the spectrograph also installed on the SAO 1-m telescope.