• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.181-182
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• 2008

In this paper, we propose a volumetric computational reconstruction method by use of smart pixel mapping technique in the computational integral imaging in order to overcome the problem of resolution degradation. The experimental results are presented to show the usefulness of our proposed technique.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.42.2-42.2
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• 2014

We present high-resolution optical spectra of newly selected candidates of intermediate-mass black holes. The sample was selected based on the variability and spectral shape in X-ray. The spectra was taken with Magellan 6.5 m Clay Telescope and cover the rest-frame region 3500-10000A. The high spectral resolution (R~4000) of the spectrum allows us to estimate BH masses of the sources. Interestingly, the majority of the sample appears to have broad emission lines. Using this dataset, we will estimate the BH masses and Eddington ratio in order to understand their physical properties.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.304-307
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• 2004

As optical fiber communication grows, the fiber alignment become the focus of industrial attention. This greatly influence the overall production rates for the opto-electric products. We proposed multi-axis nano positioning stage for optical fiber alignment. This device has 3 DOF translation and sub nanometer resolution. This nano stage consist of 3 PZT-driven flexure stages which are stacked parallel. The displacement of it is measured with capacitance gauge and is controlled by computer-embedded main controller. The design process of flexure stage using FEM is proposed and the performance evaluation of this system is verified with experiments.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.411-414
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• 2000

Optical Triangulation Probes (OTPs) are widely used for their simple structure. high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTP. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam Intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the change-coupled device(CCD). Since the peak positions of the intensity distribution are not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTP system

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.213-218
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• 2004

As optical fiber communication grows, the fiber alignment become the focus of industrial attention. This greatly influence the overall production rates for the opto-electric products. We proposed multi-axis nano positioning stage for optical fiber alignment. This device has 3 DOF translation and sub nanometer resolution. This nano stage consist of 3 PZT-driven flexure stages which are stacked parallel. The displacement of it is measured with capacitance gauge and is controlled by computer-embedded main controller. The design process of flexure stage using FEM is proposed and the performance evaluation of this system is verified with experiments.

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.6-12
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• 2000

A space-borne earth observation camera is an electro-optical instrument to measure the characteristics of the earth's surface, and to transmit the measured data to a ground station(s). The specifications of a space-borne camera, such as resolution, swath width and observation bands, are determined by its mission objectives. This paper lists some specifications of a camera suitable for small satellite and then presents an optical design, with the results of tolerancing analysis, which satisfies the given specifications. tions.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.210-216
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• 2009

In this paper the tactile sensor system based on the bending loss of optical fiber sensor is presented. The sensor array was designed with fabric structure. The optical measuring system was composed of LED for light source and CCD camera for the signal light detector. Performance of this tactile sensor system was evaluated in various environments and compared with Harmon's design criteria. The result shows that load range is 3 g$\sim$100 g, resolution is 1.5 g, hysteresis error is 1.5%. The response linearity is good and flexibility of sensor array is excellent.

• ETRI Journal
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• v.45 no.1
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• pp.60-74
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• 2023

Integration of the machine learning (ML) technique in all-optical networks can enhance the effectiveness of resource utilization, quality of service assurances, and scalability in optical networks. All-optical multistage interconnection networks (MINs) are implicitly designed to withstand the increasing highvolume traffic demands at data centers. However, the contention resolution mechanism in MINs becomes a bottleneck in handling such data traffic. In this paper, a select list of ML algorithms replaces the traditional electronic signal processing methods used to resolve contention in MIN. The suitability of these algorithms in improving the performance of the entire network is assessed in terms of injection rate, average latency, and latency distribution. Our findings showed that the ML module is recommended for improving the performance of the network. The improved performance and traffic grooming capabilities of the module are also validated by using a hardware testbed.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.105-111
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• 2006

A novel image quality evaluation method, which is based on combination of the rigorous grating diffraction theory and the ray-optic method, is proposed. It is applied for design optimization and, tolerance analysis of optical imaging systems implementing diffractive optical elements (DOE). The evaluation method can predict the quality and resolution of the image on the image sensor plane through the optical imaging system. Especially, we can simulate the effect of diffraction efficiencies of DOE in the camera lenses module, which is very effective for predicting different color sense and MTF performance. Using this method, we can effectively determine the fabrication tolerances of diffractive and refractive optical elements such as the variations' in profile thickness, and the shoulder of the DOE, as well as conventional parameters such as decenter and tilt in optical-surface alignments. A DOE-based 2M-resolution camera lens module designed by the optimization process based on the proposed image quality evaluation method shows ${\sim}15%$ MTF improvement compared with a design without such an optimization.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.159-164
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• 2006

We demonstrate a compact optical coherence tomography(OCT) system based on the optical fiber delay line controlled by a cylindrical piezo-electric transducer(PZT). An 18-m length of single mode fiber is wrapped under constant tension around a PZT. Approximately 134 windings are used. Wraps of the long length of fiber allow the small expansion of the PZT to be magnified to an optical path length delay of 0.78 m. The OCT system shows characteristics for 2-dimensional imaging, exhibiting 96.9dB of signal-to-noise ratio(SNR), $18.6{\pm}0.5\;{\mu}m$ of axial resolution, and $5\;{\mu}m$ of lateral resolution with samples.