• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.453-459
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• 2013

In phtosynthetic light harvesting complexes, the electronic transition energies of chlorophylls are influenced by the Coulombic interaction with nearby molecules. Variation of the interactions caused by structural inhomogeneity in biological environment results in a distribution of disordered electronic transition energies of chlorophylls. In order to provide a practical guide to predict qualitative tendency of such distribution, we model four porphyrin derivatives including chlorophyll a molecule interacting with an external positive charge and calculate their transition energies using the time dependent density functional method. It is found that ${\pi}-{\pi}^*$ transition energies of the molecules are generally blue-shifted by the charge because this stabilizes occupied molecular orbitals to a greater extent than unoccupied ones. Furthermore, new transitions in the visible region emerge as a result of the red-shift in energy of an unoccupied Mg orbital and it is suggested that light-induced electron transfer may occur from the tetrapyrrole ring to the central magnesium when the molecules are interacting with a positive charge.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.41-45
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• 2002

In industrial computer vision systems, the image quality is dependent on the parameters such as light source, illumination method, optics, and surface properties. Most of them are related with the lighting system, which is designed in heuristic, based on the designer's experimental knowledge, In this paper, a design code by which the optimal lighting method and light source for computer vision systems can be found are suggested based on experimental results, To prove the usefulness of the design code, it is applied to the lighting system design of the transistor marking inspection system and the results are presented.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.2
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• pp.26-31
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• 2012

A new operational concept for the CNS/ATM using the digital data communication technology and satellite navigation system is being implemented globally and the United States is the first country to apply UAT ADS-B system for general aviation. Korea also has plan to build ADS-B system for aeronautical surveillance to monitor low altitude flight of light aircraft and ultra-light flying device and the research to develop UAT ADS-B equipment is being carried out. This paper presents the application method of UAT ADS-B to support test operation with case study of foreign UAT ADS-B operation and survey of domestic environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.464-468
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• 2003

Complex impedances with frequency and voltage variation were analyzed in $ITO/Alq_3(60nm)/Al$ device structure. At low frequency, complex impedance is mostly expressed by resistive component, and at the high frequency by resistance and capacitive component. We have also evaluated resistance, capacitance and permittivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.535-536
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• 2005

Organic photovoltaic effects were studied in a device structure of ITO/CuPc/Al and ITO/CuPc/$C_{60}$/BCP/Al. A thickness of CuPc layer was varied from 10 nm to 50 nm, we have obtained that the optimum CuPc layer thickness is around 40 nm from the analysis of the current density-voltage characteristics in CuPc single layer photovoltaic cell. From the thickness-dependent photovoltaic effects in CuPc/$C_{60}$ heterojunction devices, higher power conversion efficiency was obtained in ITO/20nm CuPc/40nm $C_{60}$/Al, which has a thickness ratio (CuPc:$C_{60}$) of 1:2 rather than 1:1 or 1:3. Light intensity on the device was measured by calibrated Si-photodiode and radiometer/photometer of International Light Inc(IL14004).

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.575-575
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• 2003

The majority of studies comparing the mechanical properties of brittle dental restorative materials now include use of the Weibull Modulus (m). This modulus is determined from analysis of the statistical distribution of strength measurements, which can be determined using a variety of methods, including biaxial flexure, 3pt bend and 4pt bend. In comparing materials it is usually implicitly assumed that the modulus (m) is independent of test method although it is recognised to be highly dependent on flaw distributions. However, in some cases flaw distributions can be modified by sample preparation and test method may modify stressing patterns. This study investigated the pattern of strength and m in two light setting materials.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.443-448
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• 2012

A polarimetric experimental method was developed to determine the Jones matrix elements of transparent optical materials without sign ambiguity. A set of polarization dependent transmittance data of the samples was measured with polarizer - sample - analyzer system and another set of data was measured with polarizer - sample - quarter-wave plate - analyzer. Two data sets were compared and mathematically analyzed to obtain the correct signs of the elements of the matrix. The Jones matrix elements of a quarter-wave plate were determined to check the validity of the method. The experimentally obtained matrix elements of the quarter-wave plate were consistent with the theoretical expectations. The same method was applied to obtain the Jones matrix elements of a twisted nematic liquid crystal panel.

• ETRI Journal
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• v.41 no.1
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• pp.42-51
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• 2019

The rainbow hologram provides views of reconstruction with rainbow color within a large viewing zone. In our recent paper, a Fourier rainbow holographic display using diffraction grating and a white-light LED source was introduced. In this technique, the rainbow effect is realized by the dispersion of white-light source on diffraction grating, while the slit is implemented numerically by reducing the demands of the space-bandwidth product of the display. This paper presents a novel analysis on the visual perception of the Fourier rainbow holographic display using Wigner distribution. The view-dependent appearance of the image, including multispectral field of view and viewing zone, is investigated considering the observer and the display parameters. The resolution of the holographic view is also investigated. For this, a new quantitative assessment for image blur is introduced using Wigner distribution analysis. The analysis is supported with numerical simulations and experimentally captured optical reconstructions for the holograms of the computer model and real object generated with different slit size, reconstruction distance, and different observation conditions.

• Archives of Pharmacal Research
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• v.20 no.4
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• pp.324-329
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• 1997

AB-type amphiphilic copolymers (abbreviated as LE) composed of poly (L-leucine) (PLL) as the A component and poly (ethylene oxide) (PEO) as the B component were synthesized by the ring-opening polymerization of L-leucine N-carboxy-anhydride initiated by methoxy polyoxyethylene amine $(Me-PEO-NH_2)$ and characterized. Core-shell type nanoparticles were prepared by the diafiltration method. Particle size distribution obtained by dynamic light scattering was dependent on PLL composition and the size for LE-1, LE-2 and LE-3 was $369.6{\pm}267$, $523.4{\pm}410$ and $561.2{\pm}364 nm$, respectively. Shapes of the nanoparticies observed by transmission electron microscope (TEM) were almostly spherical. The critical micelle concentration (CMC) of the nanoparticles determined by a fluorescence probe technique was dependent on the composition of hydrophobic PLL, and the CMC for LE-1, LE-2 and LE-3 was $2.0{\times}10^{-6},1.7{\times}10^{-6}$ and $1.5{\times}10^{-6}(mol/l) $, respectively. Clonazepam release from core-shell type nanoparticles in vitro was dependent on PLL composition and drug loading content.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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• pp.31-35
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• 2014

The thickness dependent electrical, structural, and optical properties of ZnO films grown by atomic layer deposition (ALD) at various growth temperatures were investigated. In order to deposit ZnO films, diethylzinc and deionized water were used as metal precursor and reactant, respectively. ALD process window was found at the growth temperature range from $150^{\circ}C$ to $250^{\circ}C$ with a growth rate of about $1.7{\AA}/cycle$. The electrical properties were studied by using van der Pauw method with Hall effect measurement. The structural and optical properties of ZnO films were analyzed by using X-ray diffraction, field emission scanning electron microscopy, and UV-visible spectrometry as a function of thickness values of ZnO films, which were selected by the lowest electrical resistivity. Finally, the figure of merit of ZnO films could be estimated as a function of the film thickness. As a result, this investigation of thickness dependent electrical, structural, and optical properties of ZnO films can provide proper information when applying to optoelectronic devices, such as organic light-emitting diodes and solar cells.