• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.207-210
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• 2013

We report the construction of a MALDI imaging mass spectrometer equipped with a specially designed laser focusing lens, a compact aspherical singlet lens, that obtains a high-lateral imaging resolution in the microprobe mode. The lens is specially designed to focus the ionization laser (${\lambda}$ = 355 nm) down to a $1{\mu}m$ diameter with a long working distance of 34.5 mm. With the lens being perpendicular to the sample surface and sharing the optical axis with the ion path, the imaging mass spectrometer achieved an imaging resolution of as good as $5{\mu}m$ along with a high detection sensitivity of 100 fmol for peptides. The mass resolution was about 900 (m/${\Delta}m$) in the linear TOF mode. The high-resolution capability of this instrument will provide a new research opportunity for label-free imaging studies of various samples including tissues and biochips, even for the study at a single cell level in the future.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.534-541
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• 1987

The study of reaction mechanism for the substitution of ethylenediamine (en) for Cl and Hedta from $[CoCl(Hedta)]^-$ in the presence of $Hg^{2+}$ ion was carried out by uv and CD spectra. From the kinetic data, we proposed that the first ethylenediamine be substituted through the associative reaction path by means of interaction of $Hg^{2+}$ ion with Co(III), and that the second and the third ethylenediamine be substituted stepwise. From the optical purities of $[Co(en)_3]^{3+}$ which was formed after reaction, we suggested the critical stereochemical step and new substitution reaction paths.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2004.10a
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• pp.22-28
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• 2004

Pit and rim formation on the Acrylonitrile Butadiene Styrene(ABS) plastic surface was evaluated after it was irradiated by $CO_2$ and Nd:YAG laser beams. Our results show that thermal effect floor was well observed at the outer wall of pit with $CO_2$ laser irradiated while it was not the case with Nd:YAG laser irradiated. Also the volume and depth of pit formation increase proportionally with the energy intensities of two laser irradiations, but there are significant differences in the slope, width, and FWHM of the Pit formation with two types of laser irradiations. This result shows that $CO_2$ laser irradiation leads to better cooling contraction effect while Nd:YAG laser irradiation induces better recoil pressure effect during the interaction between ABS plastic and laser beam irradiation. The shape of the laser marking could vary significantly depending on the traveling path of molten plastic during injection molding of ABS plastic. Therefore, the selection of material and molding process can have a great impact on the performance of optical storage media.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2025-2037
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• 2021

The influence of lead cations on natural quartz (QZ) from Egypt as a glass shielding material for the composition with nominal formula (10Na₂O - (90 - x) QZ - xPbO (where x = 30, 35, 40, 45 and 50 mol %)) was examined. The studied samples are synthesized via the melt quenching method at 1050 ℃. The X-ray diffraction XRD patterns were confirmed the glass nature for studied samples. Moreover, the optical properties, and the transparency for all compositions were examined by UV-Vis spectroscopy. Also, the major elemental composition of the natural quartz were estimated via the X-ray fluorescence (XRF) technique. Further, the density and molar volume were determined. Furthermore, the nuclear shielding parameters such as, mass attenuation coefficient, effective atomic number, electronic density, the total atomic, and electronic cross sections as well as the mean free path, and the half value layer with different gamma ray energies (81 keV-1407 keV) were calculated. Besides, the results showed that the shielding behavior towards the gamma ray radiation for all glass samples was increased as the increment in PbO concentration in the glass system.

• ETRI Journal
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• v.43 no.5
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• pp.799-811
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• 2021

This paper considers a challenging problem: to simultaneously optimize the cost and the quality of service in opaque wavelength division multiplexing (WDM) networks. An optimization problem is proposed that takes the information including network topology, traffic between end nodes, and the target level of congestion at each link/ node in WDM networks. The outputs of this problem include routing, link channel capacities, and the optimum number of switch ports locally added/dropped at all switch nodes. The total network cost is reduced to maintain a minimum congestion level on all links, which provides an efficient trade-off solution for the network design problem. The optimal information is utilized for dynamic traffic in WDM networks, which is shown to achieve the desired performance with the guaranteed quality of service in different networks. It was found that for an average link blocking probability equal to 0.015, the proposed model achieves a net channel gain in terms of wavelength channels (𝛾_w) equal to 35.72 %, 39.09 %, and 36.93 % compared to shortest path first routing and 𝛾_w equal to 29.41 %, 37.35 %, and 27.47 % compared to alternate routing in three different networks.

• Journal of the Semiconductor & Display Technology
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• v.21 no.1
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• pp.91-94
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• 2022

Top emission organic light-emitting diode is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device. Unlike BEOLED, TEOLED contain semi-transparent metal cathode. Because of semi-transparent cathode, micro cavity effect occurs in TEOLED. We optimized this effect by changing the thickness of hole injection layer. Device consists of is indium-tin-oxide / N,N'-Di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine (x nm) / tris-(8-hydroxyquinoline) aluminum (50nm) / LiF(0.5nm) / Mg:Ag (1:9), and we changed NPB thickness which is used as HTL in our device in order to study how micro cavity effects are changed by optical path. As the results, NPB thickness at 35nm showed the current efficiency of 8.55Cd/A.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.78.1-78.1
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• 2021

A Lunar observatory not only provides ideas and experiences for space settlements from the Moon to Mars, but also puts the telescope in an optimal position to compete with space telescopes. Earth observation on the Moon's surface has the advantage of no atmospheric scattering or light pollution and is a stable fuel-free observation platform, allowing all longitude and latitude of the Earth to be observed for a month. Observing the entire globe with a single observation instrument, which has never been attempted before, and calculating the global albedo will significantly help predict the weather and climate change. Spectropolarimetric observations can reveal the physical and chemical properties of the Earth's atmosphere, track the global distribution and migration path of aerosols and air pollutants, and can also help detect very small space debris of which the risk has increased recently. In addition, the zodiacal light, which is difficult to observe from Earth, is very easy to observe from the lunar observatory, so it will be an opportunity to reveal the origin of the solar system and take a step closer to understanding the exoplanet system. In conclusion, building and developing a lunar observatory will be a groundbreaking study to become the world's leader that we have never tried before as a first step in expanding human experience and intelligence.

• Transactions of Materials Processing
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• v.32 no.6
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• pp.360-366
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• 2023

This study is concerned with the surface quality of products according to the material and coating condition of the forming tool in incremental sheet forming. Three forming tools, SKD11 with and without diamond-like-coating (DLC) and polymer tool tip, were used to form conical and pyramidal geometries to take into account the influence of friction between the forming tool and the sheet on the surface quality including geometric accuracy of deformed samples. Each test was performed using SUS304 with a thickness of 0.4 mm according to different incremental depths per lap of 0.5 mm, 1.0 mm, and 1.5 mm for the contour tool path, considering the increase in normal force which is associated with the frictional behavior during local deformation. The surface quality was then investigated through surface roughness measured with KEYENCE VR-6000 and relative strain distribution including deformed shape analyzed with ARGUS which is a non-contact optical strain measurement system. Differences between 3D CAD surfaces and captured geometry from experiments were evaluated to compare the effect of friction on geometric accuracy. From comparisons of experimental results, it was revealed that the polymer-based tool tip can improve surface quality and geometric accuracy by reducing the undesired material flow due to local friction in the increment sheet forming process.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2458-2473
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• 2024

The turbulent flow in reactor pressure vessel (RPV) of pressurized water reactor (PWR) is important for the flow rate distribution at core inlet. Thus, it is vital to study the turbulent flow phenomena in RPV. However, the complicated fluid channel consisted of inner structures of RPV will block or refract the laser sheet of particle image velocimetry (PIV). In this work, the matched index of refraction (MIR) of sodium iodide (NaI) solution and acrylic was applied to support optical path for flow field measurements by PIV in the 1/10th scaled-down RPV model. The experimental results show detailed velocity field at different locations inside the scaled-down RPV model. Some interesting phenomena are obtained, including the non-negligible counterflow at the corner of nozzle edge, the high downward flowing stream in downcomer, large vortices above vortex suppression plate in lower plenum. And the intensity of counterflow and the strength of vortices increase as inlet flow rate increasing. Finally, the case of asymmetry flow was also studied. The turbulent flow has different pattern compared with the case of symmetrical inlet flow rate, which may affect the uniformity of flow distribution at the core inlet.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.411-416
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• 2020

An optical arrangement has been set inside a photo-spectrometer to measure the reflectance of IR optics materials in mid IR range. The optical arrangement consists of equally spaced 4 gold coated full reflecting mirrors with the incidence angle of 45°. Baseline beam intensity I_B has been measured while the beam proceeds through the 4 mirrors. Reflectance of a mirror has been estimated from the I_B. And the beam intensity I_S with the specimen in the optical path has been measured with the 4th mirror replaced with the specimen. Reflectance of the specimen has been estimated from the value of I_S/I_B. Then the estimated reflectance has been put in Fresnel equation relating reflectance and refractive index(RI) to estimate the RI of the material. Measurement has been made for sapphire, germanium, magnesium fluoride, and zinc sulfide. The estimated RI of the materials are closely matching with reference data and the maximum difference less than 2% over the wavelength range 3-5㎛ for all materials tested. As an FT-IR photo-spectrometer with a broadband wavelength infrared light source is used, this method has the advantage of measuring the refractive index at multiple wavelengths in a single measurement.