• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.88.1-88.1
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• 2017

We report a novel design of the "linear astigmatism-free" three mirror system (LAF-TMS). In general, the linear astigmatism is one of the most dominant aberration degrading image qualities in common off-axis systems. The proposed LAF-TMS is based on a confocal off-axis three mirror system, where higher order aberrations are minimized via our numerical optimization. The system comprises three pieces of aluminum-alloy freeform mirrors that are feasible to be fabricated with current single-point diamond turning (SPDT) machining technology. The surface figures, dimensions, and positions of mirrors are carefully optimized for a LAF performance. For higher precision-positioning mechanism, we also included alignment parts: shims (for tilting) and L-brackets (for decentering). Any possible mechanical deformation due to assembly process as well as 1-G gravity, and its influence on optical performances of the system are investigated via the finite element (FE) analysis. The LAF-TMS has low f-number and a wide field of view, which is promising for sky monitoring programs such as supernova surveys.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.56.4-57
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• 2017

The Schwarzschild-Chang off-axis telescope is a "linear astigmatism-free" confocal system. The telescope comprises two pieces of aluminum-alloy freeform mirrors that are fabricated with diamond turning machine (DTM) process. We designed optomechanical structures where optical components in the telescope system can be adjustable on a linear stage. Optomechanical deformation caused by the weight of system itself and its temperature variation is analyzed by the finite element analysis (FEA). The results show that the deformation is estimated in the tolerance range. For the optic-axis alignment of telescope system, three-point alignment (TPA) method is chosen. The TPA method uses three parallel lasers and a plane mirror. Point source images were taken from collimated light and field observation. The performance of optical system was tested by point spread function and aberration measurement of the point sources.

• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.423-430
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• 1994

We designed and fabricated the single mode fiber pigtailed DFB-LD module for 2.5 Gbps optical communication system. In the design of the DFB-LD module, we made the module divided into two parts of inner sub-module and outer 14-pin butterfly package and cylindrical shaped sub-module contain quasi confocal 2 lens system including optical isolator and electrical connection between these parts via hybrid substrate of bias T circuit. Laser welding was used to assemble the sub-module which requires accurate fixing between optical elements. The fabricated DFB-LD module showed optical coupling efficiency of 20% and - 3 dB small signal response of more than 2.6 GHz. We confirmed mechanical reliability of the module by temperature cycle test where the tested module exhibit optical power fluctuation of less than 10%. Finally we evaluated the performance of the fabricated DFB-LD module as light source of 2.5 Gbps optical communication system, sensitivity of - 30.2 dBm was obtained through 47 km optical fiber transmission under the criterion of $1\times10^{-10}$ BER and transmission penalties were 1.5 dB caused by extinction ratio and 1.0 dB caused by chromatic dispersion of normal single mode fiber. fiber.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.916-919
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• 2012

Bioimaging that can be imaging phenomena within cells of a molecular size have been advanced in technology. We can observe clearly DNA and proteins using a confocal microscope. Currently biological fluorescent imaging area is used essentially for diagnosis and treatment in health and clinical care field. In this paper, we developed an integration management system of analyzing fluorescence images on smart phone. It can support a user to analyse fluorescence images anytime anywhere. And our system is based on client-server configuration and has functions that can figure intensity of fluorescence images and manage many imaging data. Proposed system can be a mean of ubiquitous health because it helps a doctor diagnose by analyzing fluorescence images of emergency patients without time and space restrictions.

• Korean Journal of Optics and Photonics
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• v.20 no.6
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• pp.354-360
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• 2009

We have constructed and analyzed the performance of a simple fiber bundle multi-focal microscope. The microscope had a fiber bundle substituted for micro-lens array that is the core part of MMM(multi-focal multi-photon microscope). The MMM is a type of confocal microscope. To analyze the performance and characteristics of the fiber bundle multi-focal microscope, three types of samples were used: a standard grating, USAF 1951(7, 3), and 1951(7, 6). Using two polarizers and a polarizing beam splitter, we eliminated noise and got clear images. We obtained the FWHM of fiber spot images with the standard grating using two different magnifier lenses which were 63X and 20X, and found an image of the sample as a distribution of fiber spot images. For this case we used the low magnification lens, which gives denser distribution, so that we could get clearer images. In order to test the resolution of the fiber bundle multi-focal microscopic system, we used the USAF 1951 sample which has a smaller line interval than that of the standard grating. The FWHM of the line width of the image coincides well with the real line width of the USAF 1951 sample. We confirmed the performance of a fiber bundle multi-focal microscopic system which is relatively simple but has submicron resolution and is able to get 1600 images at the same time.

• Korean Journal of Optics and Photonics
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• v.10 no.1
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• pp.1-4
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• 1999

A confocal microscope system was used to study the bursts of fluorescence photons from single dye molecules excited at 638 nm by a short-pulsed diode laser with a repetition rate of 17 MHz. A red dye, JA22, in ethylene glycol solution was used as a sample. The fluorescence decay curves of single molecules were acquired using a time-correlated single photon counting and analyzed by a maximum likelihood estimator. It was possible to measure the fluorescence decay times with an error probability of 21% at photon number of more than 40 per dye molecule.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.353-355
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• 1997

A single molecule detection system, which consists of confocal fluorescence microscope and single photon counter, has been used to observe the dye concentration dependence of photon counting rate. With increasing concentration, a saturation effect of counting is observed and demonstrated on the basis of the dead time of photon detector. The equations presented here show the relations between the counting rate and some parameters such as probe volume, quantum efficiency of detector, and fluorescence photon number entered onto detector. The signal-to-noise ratio is also discussed briefly.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.152-159
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• 2000

In piercing operation for small hole in very thin plate, micro burrs are formed. The micro burr is very difficult to remove because the thin plate is to be deformed during deburring and deteriorate accuracy. As a first step to remove the micro burrs effectively, the burr must be measured accurately as much as possible. For most micro burrs are so small as less than 10$\mu\textrm{m}$, it is very difficult to measure. Several methods are reviewed to measure the micro burr formed in piercing operation from very thin plate with thickness less than 0.1mm. Also the effective deburring methods are reviewed. Barreling ultrasonic and chemical deburring methods are performed and the results are compared.

• Natural Product Sciences
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• v.12 no.2
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• pp.79-84
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• 2006

This study presents a detailed pharmacognostical study of the root and leaf of the crude drug Clerodendrum viscosum Vent. (Verbenaceae), an important plant in the Indian system of medicine. The root and leaf samples were studied using light and confocal microscopy, WHO recommended-physicochemical determinations, and authentic phytochemical procedures. The physicochemical, morphological, and histological parameters presented in this paper may be proposed as parameters to establish the authenticity of C. viscosum root and leaf, and may possibly help to differentiate the drug from its other species.

• Natural Product Sciences
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• v.12 no.2
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• pp.104-108
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• 2006

This paper presents a detailed pharmacognostical study of the plant drug Hybanthus enneaspermus (L.) F. Muell (Violaceae), an important drug in the Indian system of medicine. The leaf and stem samples were studied using procedures of light, confocal microscopy, WHO recommended physico-chemical determinations and authentic phytochemical procedures. The physico-chemical, morphological, and histological parameters presented in this paper may be proposed as parameters to establish the authenticity of H. enneaspermus and may possibly help to differentiate the drug from its adulterants.