• Analytical Science and Technology
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• v.12 no.5
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• pp.1065-1077
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• 1999

• Proceedings of the Membrane Society of Korea Conference
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• 2003.11a
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• pp.72-75
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.255-260
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• 1993

This study proposed a new autofocusing method for a high resolution microscope with a depth of focus of a submicron range. The experimental setup was characterized by nulling method for bi-cell prhotodiode which had two active areas on sensor surface. The optical systems used in this method had was very simple and was easily matched to microscopes which had used widely. It was shown that the resolution was very high (about 20 nm) by experimental results. This method can be used in the semiconduct industry because it can find defects on the silcon wafer.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.163-164
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• 2002

In the past two decades, separations of enantiomers (optical isomers) by high-performance liquid chromatography (HPLC) have remarkably advanced ［1］. Among many commercially available chiral stationary phases (CSPs) for HPLC, polysaccharide-based CSPs are the most popular ones, which can cover the resolution of a wide range of the chiral compounds ［2, 3, 4］. Here, I will explain mainly the HPLC separation of enantiomers using these CSPs. (omitted)

• 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 Optical Society of Korea
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• v.18 no.4
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• pp.350-358
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• 2014

The collapse of Langmuir monolayers of arachidic acid (AA) on water at various rates of molecular area compression has been investigated in situ by imaging ellipsometry (IE). The thickness of the collapsed AA molecules, which are inherently inhomogeneous, was determined by IE with a spatial resolution of a few microns. For the analysis, we determined the dielectric function of AA monolayers from 380 to 1690 nm by conventional spectroscopic ellipsometry. Compression rates ranged from 0.23 to $0.94{\AA}^2/min$. A change of multilayer domains was observed in the in situ IE images. Lower compression rates resulted in more uniform collapsed films. Our experimental results correspond with previous theoretical simulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.921-930
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• 2013

Satrec Initiative successfully developed and verified a high-resolution electro-optical camera system, EOS-D Ver.1.0. We designed this system to give improved spatial and radiometric resolution compared with EOS-C series systems. The thermal control subsystem (TCS) of the EOS-D Ver.1.0 uses heaters to meet the opto-mechanical requirements during in-orbit operation and uses different thermal coatings and multi-layer insulation (MLI) blankets to minimize the heater power consumption. Also, we designed and verified a refocusing mechanism to compensate the misalignment caused by moisture desorption from the metering structure. We verified the design margin and workmanship by conducting the qualification level thermal vacuum test. We also performed the verification of thermal math model (TMM) by comparing with thermal balance test results. As a result, we concluded that it faithfully represents the thermal characteristics of the EOS-D Ver.1.0.

• Journal of the Korean Chemical Society
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• v.59 no.6
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• pp.488-492
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• 2015

In this study, the effective preparation method of (S)-(+)-pranidipine, the active component of antihypertensive drug as a calcium channel blocker, was developed using optical resolution. The racemic monocarboxylic acid 5 obtained by the hydrolysis of (±)-pranidipine was mixed with optically active quinidine to form salts, and the insoluble diastereomeric salt was collected and successive treatment with base and acid furnished (R)-(-)-carboxylic acid 7. (S)-(+)-Pranidipine was prepared by esterification of this acid with cinnamyl alcohol, and the analysis by chiral HPLC showed 100% enantiomeric excess (ee). This process would be industrially very useful to prepare chiral (S)-(+)-pranidipine, since the use of strong base and anhydrous solvents, and ultra-low temperature condition were excluded in this process.

• Journal of Periodontal and Implant Science
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• v.47 no.1
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• pp.30-40
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• 2017

Purpose: Optical coherence tomography (OCT) is a noninvasive diagnostic technique that may be useful for both qualitative and quantitative analyses of the periodontium. Micro-computed tomography (micro-CT) is another noninvasive imaging technique capable of providing submicron spatial resolution. The purpose of this study was to present periodontal images obtained using ex vivo dental OCT and to compare OCT images with micro-CT images and histologic sections. Methods: Images of ex vivo canine periodontal structures were obtained using OCT. Biologic depth measurements made using OCT were compared to measurements made on histologic sections prepared from the same sites. Visual comparisons were made among OCT, micro-CT, and histologic sections to evaluate whether anatomical details were accurately revealed by OCT. Results: The periodontal tissue contour, gingival sulcus, and the presence of supragingival and subgingival calculus could be visualized using OCT. OCT was able to depict the surface topography of the dentogingival complex with higher resolution than micro-CT, but the imaging depth was typically limited to 1.2-1.5 mm. Biologic depth measurements made using OCT were a mean of 0.51 mm shallower than the histologic measurements. Conclusions: Dental OCT as used in this study was able to generate high-resolution, cross-sectional images of the superficial portions of periodontal structures. Improvements in imaging depth and the development of an intraoral sensor are likely to make OCT a useful technique for periodontal applications.

• Journal of Periodontal and Implant Science
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• v.47 no.1
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• pp.13-19
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• 2017

Purpose: The purpose of this study was to examine whether periodontal pocket could be satisfactorily visualized by optical coherence tomography (OCT) and to suggest quantitative methods for measuring periodontal pocket depth. Methods: We acquired OCT images of periodontal pockets in a porcine model and determined the actual axial resolution for measuring the exact periodontal pocket depth using a calibration method. Quantitative measurements of periodontal pockets were performed by real axial resolution and compared with the results from manual periodontal probing. Results: The average periodontal pocket depth measured by OCT was $3.10{\pm}0.15mm$, $4.11{\pm}0.17mm$, $5.09{\pm}0.17mm$, and $6.05{\pm}0.21mm$ for each periodontal pocket model, respectively. These values were similar to those obtained by manual periodontal probing. Conclusions: OCT was able to visualize periodontal pockets and show attachment loss. By calculating the calibration factor to determine the accurate axial resolution, quantitative standards for measuring periodontal pocket depth can be established regardless of the position of periodontal pocket in the OCT image.